Submembraneous Microtubule Cytoskeleton: Biochemical and Functional Interplay of TRP Channels with the Cytoskeleton Chandan Goswami and Tim Hucho

MINIREVIEW Submembraneous microtubule cytoskeleton: biochemical and functional interplay of TRP channels with the cytoskeleton Chandan Goswami and Tim Hucho

Department for Molecular Human Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany

Keywords Much work has focused on the electrophysiological properties of transient actin; axonal guidence; cytoskeleton; growth receptor potential channels. Recently, a novel aspect of importance cone; myosin; pain; signalling complex; emerged: the interplay of transient receptor potential channels with the transient receptor potential channels; cytoskeleton. Recent data suggest a direct interaction and functional reper- tubulin; varicosity cussion for both binding partners. The bi-directionality of physical and Correspondence functional interaction renders therefore, the cytoskeleton a potent integra- C. Goswami, Department for Molecular tion point of complex biological signalling events, from both the cytoplasm Human Genetics, Max Planck Institute for and the extracellular space. In this minireview, we focus mostly on the Molecular Genetics, Ihnestrasse 73, 14195 interaction of the cytoskeleton with transient receptor potential vanilloid Berlin, Germany channels. Thereby, we point out the functional importance of cytoskeleton Fax: +49 30 8413 1383 components both as modulator and as modulated downstream effector. Tel: +49 30 8413 1243 E-mail: [email protected] The resulting implications for patho-biological situations are discussed.

(Received 15 April 2008, revised 23 June 2008, accepted 30 July 2008) doi:10.1111/j.1742-4658.2008.06617.x

The microtubule cytoskeleton plays a role in a variety with various membrane proteins, which often are part of cellular aspects such as division, morphology and of large protein complexes. The dynamic properties motility, as well as the transport of molecules and and the complexity of tubulin as an interacting protein organelles toward and from the cell membrane. in large complexes at the membrane just are beginning Although all these phenomena affect the plasma mem- to be unravelled. One apparent function is to serve as brane, however, most of the microtubule ﬁlaments do a scaffold protein and modulator of transmembrane not reach to the lipid membrane region, partially due signalling. to a thick hindering cortical actin network. However, recent studies indicate that a small number of dynamic Cytoskeletal components in signalling microtubules can extend rapidly to the cell membrane. complexes at membranes Although most contacts are established only tran- siently, there are membranous regions in which the The cytoplasmic domains of transient receptor pot- plus end of these pioneering microtubules is stabilized. ential (TRP) channels recruit large complexes of Stabilization appears to be mediated by the interaction proteins, lipids and small molecules. Depending on the

Abbreviations FHIT, fragile histidine triad protein; MAP, microtubule-associated protein; RTX, resinferatoxin; TRP, transient receptor potential; TRPV, transient receptor potential vanilloid; TRPV1, transient receptor potential vanilloid subtype 1; TRPV1-Ct, C-terminal of transient receptor potential vanilloid subtype 1; TRPV1-Nt, N-terminal of transient receptor potential vanilloid subtype 1; TRPV2, transient receptor potential vanilloid subtype 2; TRPV4, transient receptor potential vanilloid subtype 4.

4684 FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS C. Goswami and T. Hucho TRP channels and cytoskeleton regulate each other preparation method, these structures have been domains like ankyrin repeats, Ca2+-sensing EF hands, referred to as ‘signalplex’, i.e. complexes involved in phosphorylation sites, calmodulin-binding sites and a signalling events [1], or ‘channelosome’, i.e. complexes so-called ‘TRP box’. Based on their sequence, the formed around functional ion channels [2], and ⁄ or as mammalian TRP family is differentiated into six ‘lipid raft complexes’, i.e. complexes localized to this subfamilies, namely TRP canonical (TRPC), TRP membranous subdomain [3]. Proteomic studies of vanilloid (TRPV), TRP melastatin (TRPM), TRP ‘signalplexes’ or ‘channelosomes’ purified from cell polycystin (TRPP), TRP mucolipin (TRPML) and lines, as well as from brain, give both direct and indi- TRP ankayrin (TRPA) ion channels [18]. All TRP rect evidence for the presence of the cytoskeleton as channels investigated to date are involved in the detec- well as ion channels. Scaffolding adaptors like inacti- tion and ⁄ or transduction of physical and chemical vation-no-afterpotential D [4–6], Na+ ⁄ H+ exchanger stimuli. regulatory factor [7] and ezrin ⁄ moesin ⁄ radixin-binding phosphoprotein 50 [8] are also found, some of which TRPV1 and the cytoskeleton interact directly with ion channels, e.g. TRP channels [9], but also contain binding motifs for cytoskeletal Physical interaction of TRPV1 with the proteins [8,10]. Accordingly, cytoskeletal proteins such cytoskeleton as spectrin, myosin, drebrin and neurabin, as well as tubulin and actin [1,2,6,11] are confirmed components TRPV1 is the founding member of the vanilloid sub- in signalplexes and channelosomes. family of TRP channels and detects several endo- Complementary proteomic studies of purified lipid genous agonists (e.g. N-arachidonoyl-dopamine) and rafts reveal the presence of several cytoskeletal proteins noxious exogenous stimuli, such as capsaicin (the main [12,13] such as a- and b-tubulin, tubulin-specific chaper- pungent ingredient of hot chilly) and high temperature one A (a folding protein involved in tubulin dimer (> 42 C) [19,20]. TRPV1 is a nonselective cation assembly), KIF13 (a kinesin) [12], actin, nonconven- channel with high permeability for Ca2+. In recent tional myosin II and nonconventional myosin V [14]. years, TRPV1 has gained extensive attention for its Similarly, proteomics studies of the ‘membrane cyto- involvement in signalling events in the context of pain skeleton’, a submembranous fraction, which is attached and other pathophysiological conditions including to the cytoskeleton [15], and of cytoskeleton-associated cancer [21–27]. proteins in general [16], indicate the presence of lipid The interaction of TRPV1 with tubulin was first iden- raft membrane proteins as well as cytoskeletal proteins. tified through a proteomic analysis of endogenous inter- Together, these varying studies give strong evidence actors enriched from neuronal tissue [28]. The that cytoskeletal proteins are part of signalling com- interaction was then confirmed by biochemical plexes including transmembrane proteins and are approaches including co-immunoprecipitation, micro- involved in their organization at membrane. tubule co-sedimentation, pull-down and cross-linking experiments. In contrast to the tubulin cytoskeleton, the physical interaction of TRPV1 with actin or neurofila- Structural features of TRP channels ment cytoskeleton has not been observed to date [28,29]. The TRP family of ion channels is named after the The C-terminus of TRPV1 (TRPV1-Ct) is sufficient Drosophila melanogaster trp mutant, which is charac- for the interaction with tubulin while the N-terminus terized by a transient receptor potential in the photore- of TRPV1 (TRPV1-Nt) apparently does not interact ceptors in response to light [17]. In the meantime, [28]. Using deletion constructs and biotinylated pep- orthologues and paralogues of TRP channels have tides, the tubulin-binding region located within been described in organisms ranging from simple TRPV1-Ct was mapped to two short, highly basic eukaryotes to human. They share a high degree of regions (amino acids 710–730 and 770–797) [29]. If an homology in their amino acid sequence. TRP channels a-helical conformation is assumed, these two regions are formed by monomers with six transmembrane project all their basic amino acids to one side, thus regions that assemble into tetramers, which form the potentially enabling interactions with negatively functional cation-permeable pore. The most conserved charged residues (Fig. 1). Indeed, correspondingly, the region is the sixth transmembrane domain, which con- C-terminal over-hanging region of tubulin contains a stitutes most of the inner lining of the ion channel large number of negatively charged glutamate (E) resi- pore. The N- and C-termini of TRP channels are dues in a stretch characterized as unstructured region located in the cytoplasm and, depending on the respec- of the tubulin and referred as E-hook. These E-hooks tive TRP channel, consist of various functional are known to be essential for the interaction of tubulin

FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS 4685 TRP channels and cytoskeleton regulate each other C. Goswami and T. Hucho

A with various microtubule-associated proteins such as MAPs, Tau, as well as others. Indeed, binding of TRPV1-Ct with tubulin was abolished when the E-hooks containing over-hangs were removed by prote- B ase treatment [29]. The tubulin-binding region of TRPV1 apparently is under high evolutionary pressure as its sequence is highly conserved in all TRPV1 orthologues [29]. Also between homologues, the distribution of basic amino acids composing the tubulin-binding regions is conserved even though the overall amino acid conservation is rather limited. Based on these data an interaction of tubulin with TRPV2, TRPV3 and TRPV4 (Fig. 2) can also be predicted. These TRPV1 homologues have the highest conservation of basic charge distribution within the tubulin-binding sequences. Indeed, in the meantime we could conﬁrm this for Fig. 1. Characteristic of the tubulin-binding motifs located at the TRPV2 and TRPV4 (unpublished observation). C-terminus of TRPV1. (A) The extreme C-terminus of both a- and TRPV1 preferably interacts through its C-terminal b-tubulin contains highly negatively charged amino acids (indicated domain with b-tubulin and to a lesser extend also with in red) and is mostly unstructured. (B) The basic amino acids (indi- a-tubulin thereby forming a high-molecular weight cated in blue) that are located within the tubulin-binding regions of TRPV1 are located at one side of the putative helical wheel, where complex [29]. This suggests stronger binding of it can interact with the acidic C-terminus of tubulin. TRPV1 to the plus end rather than the minus end of

Fig. 2. Conservation of the tubulin-binding regions in TRPV1 orthologues and homologues. (A) The tubulin-binding region is conserved in mammals. The conserved basic amino acids are shown in blue and are indicated by an asterisk (*). NCBI accession numbers: rat (NP-114188), mouse (CAF05661), dog (AAT71314), human (NP_542437), guinea pig (AAU43730), rabbit (AAR34458), chicken (NP_989903) and pig (CAD37814). (B) TRPV1 homologues (based on sequences from rat species only) were aligned using CLUSTAL. The distribution of basic amino acids (in blue) located within the ﬁrst tubulin-binding motif is partially conserved. NCBI accession numbers: TRPV1 (NP-114188), TRPV2 (AAH89215), TRPV3 (NP-001020928), TRPV4 (NP-076460), TRPV5 (AAV31121) and TRPV6 (Q9R186).

4686 FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS C. Goswami and T. Hucho TRP channels and cytoskeleton regulate each other microtubules as the plus ends of microtubule protofila- root ganglia-derived F11 cells results in co-localization ments are decorated with b-tubulin. It is therefore of TRPV1 and microtubules and accumulation of tempting to speculate that TRPV1 may act as a micro- endogenous tyrosinated tubulin (a marker for dynamic tubule plus-end-tracking protein (+TIP) [30]. This microtubules) in close vicinity to the plasma membrane speculation is corroborated by the recent observation [28] (Fig. 3). As suggested by its preference to bind to that despite their differences in primary amino acid the plus-end-exposed b-tubulin, TRPV1 apparently sta- sequences, the crystal structures of microtubule-bind- bilizes microtubules reaching the plasma membrane ing regions of different classes of +TIP proteins such and thereby increases the number of pioneering micro- as Stu2p, EB1 and Bim1p contain a common motif of tubules within the actin cortex (Fig. 4). But stabiliza- at least two a helices with positively charged residues tion induces even stronger changes. The overall at the surface [31]. The tubulin-binding ability of cellular morphology is altered dramatically by massive TRPV1-Ct is supported by the predicted structural induction of filopodial structures in neuronal as well as models also [32,33]. This is particularly due to the fact in non-neuronal cells [40] (Fig. 4). The mechanism for that the tubulin-binding regions are predicted to con- this is currently under investigation and apparently tain a helices. Fragile histidine triad protein (FHIT), a also includes alterations in the actin cytoskeleton. But, tumour suppressor gene product has high sequence co-localization of TRPV1 with tubulin was observed homology with TRPV1-Ct and the crystal structure of all along the filopodial stalk and, of note, including FHIT was used as a template for predicting the struc- the filopodial tips [40]. Tubulin and components attrib- ture of TRPV1-Ct [32]. Remarkably, FHIT also binds uted to stable microtubules (like acetylated tubulin to tubulin [34]. and MAP2ab) were also observed within these thin Different post-translationally modified tubulin, like filopodial structures [40]. tyrosinated tubulin (a marker for dynamic microtubules), detyrosinated tubulin, acetylated tubulin, poly- TRPV1-activation induced microtubule glutamylated tubulin, phospho (serine) tubulin and disassembly neurone-specific b-III tubulin (all markers for stable microtubules) interact with TRPV1-Ct [29]. This implies In contrast to the stabilization of microtubules at rest- that TRPV1 interacts not only with soluble tubulin, but ing state, activation of TRPV1 results in rapid disas- also with assembled microtubules in various dynamic sembly of microtubules irrespective of the investigated states. And indeed, the interaction of TRPV1-Ct also cellular system (Fig. 3) [41,42]. Again, the underlying with polymerized microtubules could experimentally mechanism of TRPV1 activation-mediated cytoskele- been proven [28]. In addition to sole binding, TRPV1- ton remodelling is largely unknown. In F11 cells, Ct exerts a strong stabilization effect on microtubules, TRPV1 activation leads to an almost complete destruc- which becomes especially apparent under microtubules tion of peripheral microtubules, whereas microtubules depolymerising conditions such as presence of noco- close to the microtubule-organizing centre, a structure dazol or increased Ca2+ concentrations [28]. composed of c-tubulin and stable microtubules at the TRPV1 channels are nonselective cation channels. perinuclear region, remain intact (Fig. 3). Also, the Therefore, the role of increased concentration of Ca2+ integrity of other cytoskeletal filaments like actin and on the properties of TRPV1–tubulin and ⁄ or TRPV1– neurofilaments is not affected by activation of TRPV1 microtubule complex is of special interest. Tubulin [41]. Potentially, TRPV1 activation may even increase binding to TRPV1-Ct is increased by increased Ca2+ the amount of polymerized actin [43]. concentrations [28]. Interestingly, the microtubules Effects caused by the activation of a nonselective formed with TRPV1-Ct in the presence of Ca2+ cation channel are suggestive of mediation by the become ‘cold stable’ as these microtubules do not dep- influx of, for example, Ca2+. Indeed, high Ca2+ con- olymerise further at low temperature [28]. The exact centrations have the potential to depolymerize micro- mechanism how Ca2+ modulates these physicochemi- tubules in vitro and in vivo [44,45] through either cal properties in vitro are not clear. In this regard, it is ‘dynamic destabilization’, i.e. a direct effect of Ca2+ important to mention that tubulin has been shown to on microtubules, or indirectly by a calcium-induced bind two Ca2+ ions to its C-terminal sequence [35–38] but signal-cascade-dependent depolymerization [46]. and thus Ca2+-dependent conformational changes of Also, chelating extracellular Ca2+ with EGTA and tubulin [39] may underlie the observed effects of Ca2+. depletion of intracellular Ca2+ stores with thapsigargin The biochemical data of direct interaction as well as cannot prevent TRPV1-activation-mediated microtu- microtubule stabilization find their correlates in cell bule disassembly [41,47]. Thus, TRPV1-activation- biological studies. Transfection of TRPV1 in dorsal induced microtubule disassembly is apparently not a

FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS 4687 TRP channels and cytoskeleton regulate each other C. Goswami and T. Hucho

5 µm 10 µm

B C

10 µm

Fig. 3. TRPV1 regulates microtubule dynamics by two opposing manners. (A) In the absence of activation, TRPV1 co-localizes and stabilizes microtubules at the cell membrane. Confocal immunofluorescence images of a F11 cell and an enlarged area reveals the accumulation of tubulin (red) at the plasma membrane due to the presence of TRPV1 (green). (B) Activation of TRPV1 by RTX results in rapid the disassembly of polymerized microtubules. Filamentous microtubules disappear in the TRPV1 expressing cells but not in the nontransfected cells. (C) Detergent extraction after RTX treatment of TRPV1 expressing cells reveals loss of peripheral microtubules from majority of the cell body. The presence of microtubules is restricted only to the microtubule organizing centre region. Some fragmented microtubules near perinuclear region are also visible. direct effect of high Ca2+ concentrations. Even com- among others caspase 3 and 8, which leads eventually bined EGTA and thapsigargin, treatment cannot to cell death [55–59]. In general, extensive fragmenta- exclude small changes in local Ca2+ concentration. tion of the cellular cytoskeleton and programmed cell Therefore, these small changes in Ca2+ might trigger death correlate well. However, in response to short- an enzymatic cascade leading to depolymerization. term stimulation of TRPV1 we have not observed any This view is also supported by previous studies demon- fragmented tubulin bands in western blot analysis [41]. strating that a small amount of calmodulin can cause Last, but not least, TRPV1 activation-mediated inhibi- massive microtubule depolymerization in the presence tion of protein synthesis and endoplasmic reticulum of catalytic amounts of Ca2+, but not in the complete fragmentation may also have impact on the microtu- absence of Ca2+ [45,48–50]. Subsequent activation of bule integrity [42]. Ca2+-dependent proteases may also trigger proteolysis of structural proteins as a downstream effect [51]. Implications of TRPV1-induced cytoskeleton Another potential mechanism that can lead to rapid destabilization disassembly of microtubules might be the phosphorylation of microtubule-associated proteins (MAPs). We TRPV1 affects biological functions, like cell migration observed fragmented microtubules all over the cyto- and neuritogenesis, that are largely dependent on the plasm after TRPV1 activation, which suggest that cytoskeleton [42,60,61]. Indeed, rapid disassembly of specific microtubule-severing proteins like katanin, dynamic microtubules by TRPV1 activation has a fidgetin and spastin are probably also involved in this strong effect on axonal growth, morphology and process (Fig. 3) [52–54]. Prolonged stimulation of migration. TRPV1 is endogenously expressed already TRPV1 activates through high Ca2+ concentrations at an early embryonic stage and localizes to neurites

4688 FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS C. Goswami and T. Hucho TRP channels and cytoskeleton regulate each other

A B i ii iii

C D

Fig. 4. Effect of TRPV1–cytoskeletal cross-talk on neuritis and growth cones. (A) At growth cones, TRPV1-enriched plasma membranes sta- bilize pioneer microtubules within the ﬁlopodial structures. (B) Such stabilization of the microtubule results in the induction of neuritogenesis and the formation of elongated cells. (C) Time series of a growth cone developed from F11 cell expressing TRPV1–GFP. Application of RTX results in rapid collapse and retraction of the growth cone. (D) Longer neurites develop multiple varicosities (arrow heads) after RTX application due to disassembly of microtubules. Such varicosities are not visible in TRPV1 expressing cells in absence of activation. Even in case of neurites developed from non-TRPV1 expressing cells, RTX application remains ineffective and do not produce such varicosities. and growth cones (Fig. 4) [47,62]. Activation of Thus, activation of TRPV1 in a speciﬁc cellular region TRPV1 results in rapid disassembly of microtubules may result in the disassembly of microtubules, thereby within neurites (and also at growth cones) while keep- facilitating the retraction of that part of the cell, thus ing the actin cytoskeleton intact and functional. This creating a trailing edge. By contrast, stabilization of destroys the balance between the anterograde force microtubules at TRPV1-enriched plasma membranes (generated by microtubule cytoskeleton) and the retro- may facilitate a cell to extend at this region, marking grade force (generated by actin cytoskeleton) that the leading edge and initiating cell migration [66]. determines the axonal morphology and the net neurite In contrast to a strong and long-term activation of growth [63,64]. Sudden loss of polymerized micro- TRPV1, which affects microtubules globally, mild and tubules results in retraction of growth cones and for- localized short-term activation may affect parts of the mation of varicosities all along the neurites (Fig. 5). cytoskeleton differently. Thus, growth cones may be Long-term low-level TRPV1 activation by an endo- helped to avoid a repulsive guidance cue. Reciprocally, genous ligand results in shortening of neurites in pri- stabilization effect of TRPV1-enriched membranes on mary neurons [47]. But as endogenous expression of the plus ends of microtubules may help a growth cone TRPV1 is widespread and not restricted to neuronal to steer towards an attractive cue (Fig. 4). A similar cells, activation of TRPV1 increases the motility of mechanism by which other TRP channels can regulate non-neuronal cells like HepG2 and dendritic cells the growth cone attraction, repulsion or retraction has [42,65]. In agreement with the role of TRPV1 in cell been described [67,68]. Although not tested, TRPV1 motility, dendritic cells from trpv1 - ⁄ - animal show less may potentially regulate the sperm motility as the pres- migration than wild-type [65]. ence of TRPV1 at the sperm acrosome and throughout Differential activation of TRPV1 complexes can the tail has been reported [69]. Short-term and low- create an asymmetry in the microtubular organization. level activation may increase sperm motility whereas

FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS 4689 TRP channels and cytoskeleton regulate each other C. Goswami and T. Hucho

A B stimuli. In many studies, the synthetic ligand 4a-PDD is alternatively employed [70]. TRPV4 is involved in mechanosensation of the normal and the sensitized neuron [71]. To date, the evidence for the functional, as well as physical, interaction of TRPV4 with cytoskeletal components is mostly indirect. For C example, TRPV4 has been shown to be important for the development of taxol-induced mechanical hyperalgesia suggesting a functional link of TRPV4 with microtubule cytoskeleton [72]. Often, activation of TRPV4 is correlated to cellular changes, which in turn are known to involve cytoskeletal rearrangement such as cell volume in regulatory volume decrease [72–74] and cell motility due to changes in lamellipo- dia dynamics [60]. However, the extent to which the changes in the cytoskeleton are induced by TRPV4 directly is mostly unknown. Biochemical and cell biological data are sparse and patchy. The distance Fig. 5. Schematic model depicting how TRPV1 regulates growth between actin and TRPV4 in a live cell was meas- cone and neurite movement via cytoskeletal reorganization. (A) ured by FRET to be < 4 nm [75] assuring, that Presence of microtubule cytoskeleton (Mt, red) and actin cytoskele- these two components have the potentiality to inter- ton (blue) at the neurite and at the growth cones are shown. Both an anterograde force from microtubule cytoskeleton (up arrow) and act with each other. In addition, TRPV4 has been a retrograde force provided by actin cytoskeleton (down arrow) identified by yeast two-hybrid screen to interact with determine the net axonal growth and movement. (B) Most of the MAP7, an interaction confirmed by immunoprecipi- axonal microtubules is restricted to the central zone (C-zone) of the tation as well as pull-down experiments [76]. This growth cone. Few dynamic pioneer microtubules at the peripheral interaction is dependent on the C-terminal amino zone (P-zone) are selectively stabilized by TRPV1-enriched mem- acids 798–809. Interestingly, the C-terminal cyto- brane patches (green stars). This may have implications for the plasmic domain of TRPV4 also contains a partially turning of the growth cone in response to a signal (green asterisk). (C) TRPV1 activation-mediated growth cone retraction and varicos- conserved putative tubulin-binding site [29]. ity formation is dependent on the degree of microtubule disassembly. (Stage 1) Activation of TRPV1 (indicated by arrow) results in Physical and functional interaction of the partial disassembly of microtubules, leading to the retraction of growth cone. (Stage 2) Further disassembly leads to more retrac- other TRP channels with cytoskeletal tion and initiates varicosity formation. (Stage 3) Complete disas- components sembly of microtubules results in a stage where further retraction Physical links of several TRP channels other than is no more possible. (Stage 4) The force from the functional actin cytoskeleton and complete disassembled microtubules results in TRPV1 and TRPV4 with the cytoskeleton have been the varicosity formation. Strong agonists like RTX result in a quick established. For example, b-tubulin interacts directly and irreversible shift to stage 3 and 4. By contrast, transient and with TRPC1 [77]. Two other members of the TRPC mild activation by endogenous ligands like N-arachidonoyl-dopamine family, TRPC5 and TRPC6, are also interacting with results in retraction for a longer time but rarely forms varicosities, cytoskeletal proteins [1]. These also include actin and indicating that N-arachidonoyl-dopamine most likely results in slow tubulin as they are confirmed components of the puri- and reversible shifting at stage 1 and 2. fied ‘signalplex’ [1]. TRPC5 interacts with stathmin 2, a microtubule cytoskeleton-binding protein [78]. Direct robust activation may cause a non-motile sperm due physical and functional interplay with both the micro- to complete disassembly of microtubules at the sperm tubule and actin cytoskeleton has also been described tail. for TRPP channels (see minireview by Chan et al. in this series). Apart from the direct interaction, many of these TRPV4 and the cytoskeleton TRP channels are localized to the microtubule and TRPV4 is a member of the TRPV subfamily and a actin cytoskeleton-enriched structures like filopodia, close homologue of TRPV1. It is activated by cilia and growth cones, indicating a potential associa- endogenous endovanilloids, by temperatures of tion and complex signalling with the cytoskeleton. >37C, and by both hypo- and hyperosmotic Again, activation of these TRP channels correlates

4690 FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS C. Goswami and T. Hucho TRP channels and cytoskeleton regulate each other with cytoskeleton-dependent morphological changes. TRP channels and myosin motors For example, both rat and human pulmonary arterial endothelial cells express TRPP1, the activation of Nonconventional myosin motors and TRP channels are which leads to a change in cell shape due to reorgani- often localized within specific subcellular regions such zation of cortical actin network [79]. Likewise, Xeno- as filopodia or ciliary tips. These two groups of proteins pus TRPN1 (NOMPC) localizes to microtubule-based also share a special genotype–phenotype correlation as cilia in epithelial cells, including inner ear hair cells abnormal expression ⁄ function of these myosins or [80]. TRPs gives rise to similar pathophysiological conditions Almost all of the TRPC channels have been reported like deafness, blindness, and syndromes affecting the to localize to growth cones [67,77,81–84]. In all cases, function of other tissues and ⁄ or organs. For example, activation of TRPC channels regulates growth cone in case of deafness, several nonconventional myosin morphology and motility in response to chemical guid- motors (myosin I, IIA, IIIA, VI, VIIA and XV) are ance cues. TRPC1 modulates the actin cytoskeleton by important for either development of the stereocilia of modulating ADF ⁄ cofilin activity via LIM kinase [85]. hair cells in the inner ear or proper localization of TRP It is involved in growth cone turning in response to channels at the tip of these stereocilia, which is crucial Netrin 1 [82,83]. TRPC4 is upregulated after nerve for the activity of these cells [91,92]. Reciprocally, muta- injury and is important for neurite outgrowth [81]. tions and abnormal expression ⁄ function of several TRP TRPC3 and TRPC6 are important for growth cone channels (TRPML1, TRPML2, TRPML3, TRPV4, turning in response to brain-derived neurotrophic TRPV5 and TRPV6) also lead to deafness [93–97]. In a factor [84]. Likewise, TRPC5 expression results in similar manner, both myosins and TRP channels are increased length of neurites and filopodia [78]. causally involved in blindness. Recently it has been In addition to data on the interaction of TRP chan- reported that translocation of eGFP-tagged TRP-like nels with the cytoskeleton, there are few examples sug- channels to the rhabdomeral membrane in Drosophila gesting that the activity of the TRP channel is photoreceptors is myosin III dependent [98]. Apart influenced by the cytoskeleton. Mostly, alteration of from the above genetic interactions, TRP channels the cytoskeleton results in inhibition of TRP channel interact directly with myosins. Using a proteomic opening. For example, the requirement for a functional screen, myosin was identified to bind to TRPC5 and cytoskeleton in the activation of TRP channels in TRPC6 [1]. Another study showed that myosin IIa is store-mediated Ca2+ entry and ⁄ or store-operated directly phosphorylated by TRPM7, a cation channel Ca2+ entry has been reported [86–88]. In human plate- fused to an alpha-kinase [99]. This phosphorylation in lets, physical coupling of hTRP1 with inositol 1,4,5-tri- turn regulates cell contractility and adhesion. Notably, phosphate receptor (IP3R), a prerequisite step for TRPM7 phosphorylates positively charged coiled-coil store-mediated Ca2+ entry, depends on the degree of domain of myosin II [100]. polymerized actin [86,87]. Disruption of the actin cyto- In some cases, similar cellular phenotypes also skeleton by cytochalasin D also prevents phosphatidyl- suggest a functional link between TRP channels and inositol 4,5-bisphosphate (PIP2)-mediated inhibition of nonconventional myosin motors. For example, we TRPC4a [89]. Another example has been reported observed that ectopic expression of TRPV1 induces from primary human polymorphonuclear neutrophil extensive filopodial and neurite-like structures in neu- cells, in which reorganization of actin results in the ron-derived F11 cells as well as in non-neuronal cells internalization of endogenous TRPC1, TRPC3 and (e.g. HeLa, Cos and HEK 293 cells) [40]. Interestingly, TRPC4 from plasma membrane to the cytosol, which TRPV1 expression induces club-shaped filopodia with correlates well with the loss of store-operated calcium a bulbous head structure that contains negligible entry [88]. Accordingly, pre-disruption of the actin amount of F-actin but accumulates TRPV1 [40]. This cytoskeleton by cytochalasin D rescues the loss of phenotype resembles the dominant negative effect of store-operated calcium entry, indicating that the actin the expression of the non-conventional myosin II, III, dynamics are important for this TRPC-mediated store- V, X and XV [101–112]. This renders the observation operated calcium entry. Apparently, an intact actin that TRPV1 expression induces drastic upregulation of cytoskeleton is also essential for strong agonist-medi- endogenous myosin IIa and IIIa temptingly suggestive ated activation of TRPC7. Thus, pharmacological dis- [40]. In addition, the subcellular distribution of myo- ruption of the actin cytoskeleton results in reduced sins is markedly changed from a uniformly cytoplasmic agonist-induced activation [90]. All these examples sug- to a strongly clustered localization mostly at the gest that the cytoskeleton can indeed act as modulators cell periphery [40]. In another study, cardiac-specific of TRP channel function. overexpression of TRPC6 in transgenic mice resulted

FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS 4691 TRP channels and cytoskeleton regulate each other C. Goswami and T. Hucho in an increase expression of beta-myosin heavy chain modulation of TRP channels occurs through direct [113]. Such phenomena strongly suggest the coopera- interaction with the cytoskeleton remains to be proven. tive role of myosins and TRP channels in development In addition to purely circumstantial evidence, few as well as proper function of ciliary and filopodial studies attempted the establishment of a direct modu- structures. latory role of the cytoskeleton, the best of which was The molecular mechanisms behind the increased performed on TRPP channels [125,126]. Montalbetti expression of these myosins are poorly understood. In and co-workers isolated syncytiotrophoblast apical some cases, TRP channels apparently increase myosin membrane vesicles from human placenta, and per- expression by regulating transcription factors [113]. As formed single-channel electrophysiological experiments myosins are also susceptible to protease-mediated deg- of polycystin channel 2 (PC2) on reconstituted lipid radation; a higher level of endogenous myosin might bilayers. This system eliminates all factors except the also imply less proteolytic degradation. It is therefore channel-associated complex. Biochemical analysis worth exploring how TRP channels affect the distribu- revealed the presence of actin, the actin-related compo- tion, function and endogenous level of myosins. nents a-actinin and gelsolin, tubulin including acetylated a-tubulin, and the kinesin motor proteins KIF3A and KIF3B in these membranes [125,126]. PC2 chan- Modulation of TRP ion channels nels interact directly with KIF3. Disruption of actin activities by the cytoskeleton filaments with cytochalasin D or with the actin-sever- TRP channels can be modulated by Ca2+-dependent ing protein gelsolin activates the channel. This activa- or Ca2+-independent mechanisms. Desensitization can tion can be inhibited by the addition of soluble be initiated by the Ca2+-influx through the channel monomeric G-actin with ATP, which induces actin itself and is manifested through phosphorylation– polymerization. This indicates that actin filaments, but dephosphorylation of the TRP channel and ⁄ or by the not soluble actin, are an endogenous negative regulator Ca2+-dependent interaction with calmodulin at the of PC2 channels. Also microtubules regulate PC2 C-termini of, for example, TRPV1 and TRPV4 [114– channel function only in opposing manner. Depoly- 121]. As an example of Ca2+-independent mechanisms, merization of microtubules with colchicine rapidly the channel inactivation through physical interaction inhibits the basal level of PC2 channel activity, of the TRPC channel with the cytoplasmic protein whereas polymerization and ⁄ or stabilization of micro- homer has been described. TRPC mutants lacking the tubules from soluble tubulin with GTP and taxol stim- homer-binding site become constitutively active [9]. ulates the PC2 channel activity [125]. Involvement of This latter example spurs one to hypothesize whether the microtubule cytoskeleton in the regulation of PC2 other scaffolding proteins than homer, such as actin channel has also been described in vivo in primary cilia and ⁄ or tubulin, can regulate TRP channel properties of renal epithelial cells [127]. In that system, addition though to date the experimental evidence is only cir- of microtubule destabilizer (colchicine) rapidly abol- cumstantial. Modulation of TRPV4 by a cytosolic ished channel activity, whereas the addition of micro- component is suggested, as the channel can be acti- tubule stabilizers (taxol) increased channel activity vated by heat only if analysed using whole-cell record- [127]. Similar results were obtained using reconstituted ings and not in excised patches of cell-free membranes lipid bilayer system, which reveals that both spontane- [122,123]. In turn, the involvement of cytoskeletal com- ous activity and the opening probability of TRPP3 ion ponents in the regulation of TRPV4 channel activity channels is increased by the addition of a-actinin, dem- has been demonstrated experimentally by the addition onstrating that this channel can be indeed modulated of cytoskeletal regulating drugs. The microtubule stabi- by cytoskeleton [128]. lizer taxol reduces TRPV4-dependent currents while the microtubule-disrupting agents colchicine and vin- TRPV1, TRPV4 and the cytoskeleton in cristine as well as actin cytoskeleton regulating drugs pathophysiological conditions like phalloidin (a stabilizer) or cytochalasin B (a destabilizer) do not alter the TRPV4-mediated current [76]. The importance of TRP channels in the development of In the same manner, mechanosensitive ion channel disease becomes increasingly evident. In particular, activity in cultured sensory neurons appears to depend TRPV channels are involved in various aspects of pain largely on the status of the cytoskeleton. Thus, disrup- such as inflammatory pain, cancer pain and neuropathic tion of actin or microtubule cytoskeleton by pharma- pain, as well as other diseases including allergy, diabetes cological agents greatly reduces the activity of and cough [129]. Indeed, data tie TRPV1 and TRPV4 mechanosensitive channels [124]. However, if the to the status of the cytoskeleton in models of pain. For

4692 FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS C. Goswami and T. Hucho TRP channels and cytoskeleton regulate each other example, rapidly dividing cancer cells are pharmacolog- However, the deleterious effect of TRP channels on ically targeted by modulators of the microtubule cyto- the specific subtype of neurons or cells has some clini- skeleton such as taxol, vincristin and their derivatives. cal advantages. In fact, retraction and degeneration of But in addition to the deleterious effect of these agents a subset of sensory neurons (specifically TRPV1- on the cancer, if applied systemically over the long-term expressing neurons), which involve events that affect they are highly potent inducers of strong neuropathic the integrity of the cytoskeleton, forms the basis for pain [130–132]. Systemic vincristine treatment strongly the analgesic effect of topical capsaicin-cream treat- alters the cytoskeletal architecture [133,134]. On a ment [155]. Resinferatoxin (RTX), a potent agonist of shorter timescale, inflammatory signalling pathways TRPV1 has been used successfully to eliminate pancre- leading to sensitization in a healthy animal are depen- atic cancerous cells because TRPV1 is highly expressed dent on both the ‘integrity’ and the ‘dynamics’ of the in this pancreatic cancer conditions [143–146]. Such microtubule cytoskeleton [135,136]. Short-term modula- clinical application of agonists specific for different tion of the cytoskeleton abolishes inflammatory media- TRP channels may, therefore, turn out to be effective tor-induced sensitization [135]. The precise mechanism and has full potential as chemotherapeutics. Based on by which vinca-drugs and taxoid-group-containing mol- this approach, recently use of TRP agonists as thera- ecules influence pain is not clear. Vincristine by itself is peutics is becoming popular in ‘TRPpathies’ or ‘chan- known to form tubulin paracrystals [137]. Taxol can nelopathies’ [156]. also form crystals, which can masquerade as stabilized microtubules and can rapidly incorporate tubulin Concluding remarks dimers [138]. In addition, a unique type of straight GDP–tubulin protofilament forms in the presence of The last few years have seen rapid progress in the taxol [139]. Whether these uncommon altered physical study of TRP channels as well as other ion channels in forms of tubulins ⁄ microtubules are important for pain the context of both actin and the microtubule cytoskel- development remains a central question. However, eton. The presence of the microtubule cytoskeleton at more subtle effects like differential binding properties the membrane is now beyond doubt [157]. The role of to other proteins might play a role. microtubule plus-end-binding proteins for specific sort- In addition, the involvement of several TRP chan- ing and targeting of different ion channels, receptors nels in the development of cancer and cancer pain is to specific regions of the membrane is well established increasingly prominent [22,140–142]. Endogenous [158]. However, the functional implications of this expressions of some TRP channels are either upregu- remain one of the current challenges. We find the role lated or downregulated in different tumours, cancerous of the cytoskeleton to be both direct and indirect. In tissue and also in different cancerous cell lines. For particular, the inside-out modulation of ion channels example, TRPV1 is overexpressed in bone cancer, emerges as a peculiarly novel aspect with wide ranging prostate cancer and pancreatic cancer [143–146]. Along consequences for both the pathological and the general the same lines, TRPV4, which is involved in mechano- homeostatic state. Because the large extended structure sensation, has been shown to be essential for the devel- of the cytoskeleton is able to potentially integrate opment of chemotherapy-induced neuropathic pain in signalling events from very distant sides, single signals the rat [72]. as well as associative stimuli will have to be investi- TRP channels also share functional links with the gated. In addition, the cytoskeleton has been proven cytoskeleton by other means, namely cytotoxicity and to be both a target of signalling cascades and to initi- cell death. For example, activation of TRPV1 leads to ate them itself. Thus it has the potential to recruit the inhibition of protein synthesis and endoplasmic feedback and feed-forward regulation of a number of reticulum fragmentation [42]. Prolonged stimulation cellular effects. This renders the cytoskeleton as an with capsaicin induces apoptosis in TRPV1 expressing interesting target for therapeutic approaches with neurons by activating different caspase pathways respect to the TRP channels with much to discover. (mainly caspase 8, caspase 3) [55–58,147–153]. How- ever, whether the cytotoxicity and cell death described Acknowledgements above is due to disassembly of microtubule has not been tested. Loss of TRPV1-expressing neurons ⁄ cells We thank Julia Kuhn for critically reading this mini- from specific tissues are functionally linked with the review and for her suggestions. We thank Prof. development of patho-physiological conditions. For H. H. Ropers for supporting this work. Funding from example, loss of TRPV1 positive neurons in liver is Max Planck Institute for Molecular Genetics (Berlin, linked with diabetes [154]. Germany) is gratefully acknowledged. We regret for

FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS 4693 TRP channels and cytoskeleton regulate each other C. Goswami and T. Hucho not been able to mention many of the relevant cita- by liquid chromatography-matrix-assisted laser desorp- tions due to space limitation. tion ⁄ ionization tandem mass spectrometry. Proteomics 4, 3156–3166. 13 Foster LJ, De Hoog CL & Mann M (2003) Unbiased References quantitative proteomics of lipid rafts reveals high speci- 1 Goel M, Sinkins W, Keightley A, Kinter M & Schilling ficity for signaling factors. Proc Natl Acad Sci USA WP (2005) Proteomic analysis of TRPC5- and 100, 5813–5818. TRPC6-binding partners reveals interaction with the 14 Ishmael JE, Safic M, Amparan D, Vogel WK, Pham plasmalemmal Na(+) ⁄ K(+)-ATPase. Pflugers Arch T, Marley K, Filtz TM & Maier CS (2007) Nonmuscle 451, 87–98. myosins II-B and Va are components of detergent- 2 Ambudkar IS & Ong HL (2007) Organization and resistant membrane skeletons derived from mouse fore- function of TRPC channelosomes. Pflugers Arch 455, brain. Brain Res 1143, 46–59. 187–200. 15 Nebl T, Pestonjamasp KN, Leszyk JD, Crowley JL, 3 Sanxaridis PD, Cronin MA, Rawat SS, Waro G, Ach- Oh SW & Luna EJ (2002) Proteomic analysis of a arya U & Tsunoda S (2007) Light-induced recruitment detergent-resistant membrane skeleton from neutrophil of INAD-signaling complexes to detergent-resistant plasma membranes. J Biol Chem 277, 43399–43409. lipid rafts in Drosophila photoreceptors. Mol Cell Neu- 16 Meng X & Wilkins JA (2005) Compositional character- rosci 36, 36–46. ization of the cytoskeleton of NK-like cells. J Proteome 4 Shieh BH & Zhu MY (1996) Regulation of the TRP Res 4, 2081–2087. Ca2+ channel by INAD in Drosophila photoreceptors. 17 Minke B (1977) Drosophila mutant with a transducer Neuron 16, 991–998. defect. Biophys Struct Mech 3, 59–64. 5 Huber A, Sander P, Gobert A, Ba¨hner M, Hermann R 18 Clapham DE (2003) TRP channels as cellular sensors. & Paulsen R (1996) The transient receptor potential Nature 426, 517–524. protein (Trp), a putative store-operated Ca2+ channel 19 Caterina MJ, Schumacher MA, Tominaga M, Rosen essential for phosphoinositide-mediated photorecep- TA, Levine JD & Julius D (1997) The capsaicin recep- tion, forms a signaling complex with NorpA, InaC and tor: a heat-activated ion channel in the pain pathway. InaD. EMBO J 15, 7036–7045. Nature 389, 816–824. 6 Li HS & Montell C (2000) TRP and the PDZ protein, 20 Huang SM, Bisogno T, Trevisani M, Al-Hayani A, De INAD, form the core complex required for retention Petrocellis L, Fezza F, Tognetto M, Petros TJ, Krey of the signalplex in Drosophila photoreceptor cells. JF, Chu CJ et al. (2002) An endogenous capsaicin-like J Cell Biol 150, 1411–1422. substance with high potency at recombinant and native 7 Voltz JW, Weinman EJ & Shenolikar S (2001) Expand- vanilloid VR1 receptors. Proc Natl Acad Sci USA 99, ing the role of NHERF, a PDZ-domain containing 8400–8405. protein adapter, to growth regulation. Oncogene 20, 21 Jordt SE & Ehrlich BE (2007) TRP channels in disease. 6309–6314. Subcell Biochem 45, 253–271. 8 Mery L, Strauss B, Dufour JF, Krause KH & Hoth M 22 Prevarskaya N, Zhang L & Barritt G (2007) TRP (2002) The PDZ-interacting domain of TRPC4 con- channels in cancer. Biochim Biophys Acta 1772, 937– trols its localization and surface expression in HEK293 946. cells. J Cell Sci 115, 3497–3508. 23 Birder LA (2007) TRPs in bladder diseases. Biochim 9 Yuan JP, Kiselyov K, Shin DM, Chen J, Shcheynikov Biophys Acta 1772, 879–884. N, Kang SH, Dehoff MH, Schwarz MK, Seeburg PH, 24 Szallasi A, Cortright DN, Blum CA & Eid SR (2007) Muallem S et al. (2003) Homer binds TRPC family The vanilloid receptor TRPV1: 10 years from channel channels and is required for gating of TRPC1 by IP3 cloning to antagonist proof-of-concept. Nat Rev Drug receptors. Cell 114, 777–789. Discov 6, 357–372. 10 Tang Y, Tang J, Chen Z, Trost C, Flockerzi V, Li M, 25 Liddle RA (2007) The role of transient receptor poten- Ramesh V & Zhu MX (2000) Association of mamma- tial vanilloid 1 (TRPV1) channels in pancreatitis. Bio- lian trp4 and phospholipase C isozymes with a PDZ chim Biophys Acta 1772, 869–878. domain-containing protein, NHERF. J Biol Chem 275, 26 Levine JD & Alessandri-Haber N (2007) TRP chan- 37559–37564. nels: targets for the relief of pain. Biochim Biophys 11 Sinkins WG, Goel M, Estacion M & Schilling WP Acta 1772, 989–1003. (2004) Association of immunophilins with mammalian 27 Immke DC & Gavva NR (2006) The TRPV1 receptor TRPC channels. J Biol Chem 279, 34521–34529. and nociception. Semin Cell Dev Biol 17, 582–591. 12 Li N, Shaw AR, Zhang N, Mak A & Li L (2004) Lipid 28 Goswami C, Dreger M, Jahnel R, Bogen O, Gillen raft proteomics: analysis of in solution digest of C & Hucho F (2004) Identification and characteriza- 2+ sodium dodecyl sulfate-solubilized lipid raft proteins tion of a Ca -sensitive interaction of the vanilloid

4694 FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS C. Goswami and T. Hucho TRP channels and cytoskeleton regulate each other

receptor TRPV1 with tubulin. J Neurochem 91, Ca2+ entry in neutrophils. Toxicol Appl Pharmacol 1092–1103. 209, 134–144. 29 Goswami C, Hucho TB & Hucho F (2007) Identifica- 44 Karr TL, Kristofferson D & Purich DL (1980) Mecha- tion and characterisation of novel tubulin-binding nism of microtubule depolymerization. Correlation of motifs located within the C-terminus of TRPV1. rapid induced disassembly experiments with a kinetic J Neurochem 101, 250–262. model for endwise depolymerization. J Biol Chem 255, 30 Lansbergen G & Akhmanova A (2006) Microtubule 8560–8566. plus end: a hub of cellular activities. Traffic 7, 499– 45 Job D, Fischer EH & Margolis RL (1981) Rapid disas- 507. sembly of cold-stable microtubules by calmodulin. Proc 31 Slep KC & Vale RD (2007) Structural basis of micro- Natl Acad Sci USA 78, 4679–4682. tubule plus end tracking by XMAP215, CLIP-170, and 46 Lieuvin A, Labbe´JC, Doreé M & Job D (1994) Intrin- EB1. Mol Cell 27, 976–991. sic microtubule stability in interphase cells. J Cell Biol 32 Vlachova´V, Teisinger J, Susańkova´K, Lyfenko A, 124, 985–996. Ettrich R & Vyklicky´L (2003) Functional role of 47 Goswami C, Schmidt H & Hucho F (2007) TRPV1 at C-terminal cytoplasmic tail of rat vanilloid receptor 1. nerve endings regulates growth cone morphology and J Neurosci 23, 1340–1350. movement through cytoskeleton reorganization. FEBS 33 Garcıá-Sanz N, Fernańdez-Carvajal A, Morenilla-Palao J 274, 760–772. C, Planells-Cases R, Fajardo-Sańchez E, Fernańdez- 48 Yamamoto H, Fukunaga K, Tanaka E & Miyamoto E Ballester G & Ferrer-Montiel A (2004) Identification of (1983) Ca2+ - and calmodulin-dependent phosphory- a tetramerization domain in the C-terminus of the lation of microtubule-associated protein 2 and tau vanilloid receptor. J Neurosci 24, 5307–5314. factor, and inhibition of microtubule assembly. 34 Chaudhuri AR, Khan IA, Prasad V, Robinson AK, J Neurochem 41, 1119–1125. Luduenã RF & Barnes LD (1999) The tumor suppres- 49 Keith C, DiPaola M, Maxfield FR & Shelanski ML sor protein Fhit. A novel interaction with tubulin. (1983) Microinjection of Ca++-calmodulin causes a J Biol Chem 274, 24378–82432. localized depolymerization of microtubules. J Cell Biol 35 Hayashi M & Matsumura F (1975) Calcium binding to 97, 1918–1924. bovine tubulin. FEBS Lett 58, 222–225. 50 Lee YC & Wolff J (1982) Two opposing effects of cal- 36 Solomon F (1977) Binding sites for calcium on tubulin. modulin on microtubule assembly depend on the pres- Biochemistry 16, 358–363. ence of microtubule-associated proteins. J BiolChem 37 Serrano L, Valencia A, Caballero R & Avila J (1986) 257, 6306–6310. Localization of the high affinity calcium-binding site 51 Chard PS, Bleakman D, Savidge JR & Miller RJ on tubulin molecule. J Biol Chem 261, 7076–7081. (1995) Capsaicin-induced neurotoxicity in cultured dor- 38 Fong KC, Babitch JA & Anthony FA (1988) sal root ganglion neurons: involvement of calcium-acti- Calcium binding to tubulin. Biochim Biophys Acta 952, vated proteases. Neuroscience 65, 1099–1108. 13–19. 52 McNally FJ & Vale RD (1993) Identification of kata- 39 Soto C, Rodriguez PH & Monasterio O (1996) nin, an ATPase that severs and disassembles stable Calcium and gadolinium ions stimulate the GTPase microtubules. Cell 75, 419–429. activity of purified chicken brain tubulin through a 53 Baas PW, Karabay A & Qiang L (2005) Microtubules conformational change. Biochemistry 35, 6337–6344. cut and run. Trends Cell Biol 15, 518–524. 40 Goswami C & Hucho T (2007) TRPV1 expression- 54 Ahmad FJ, Yu W, McNally FJ & Baas PW (1999) An dependent initiation and regulation of filopodia. essential role for katanin in severing microtubules in J Neurochem 103, 1319–1333. the neuron. J Cell Biol 145, 305–315. 41 Goswami C, Dreger M, Otto H, Schwappach B & 55 Sancho R, de la Vega L, Appendino G, Di Marzo Hucho F (2006) Rapid disassembly of dynamic micro- V, Macho A & Munoz E (2003) The CB1 ⁄ VR1 tubules upon activation of the capsaicin receptor agonist arvanil induces apoptosis through an TRPV1. J Neurochem 96, 254–266. FADD ⁄ caspase-8-dependent pathway. Br J Pharma- 42 Han P, McDonald HA, Bianchi BR, Kouhen RE, Vos col 140, 1035–1044. MH, Jarvis MF, Faltynek CR & Moreland RB (2007) 56 Shin CY, Shin J, Kim BM, Wang MH, Jang JH, Surh Capsaicin causes protein synthesis inhibition and YJ & Oh U (2003) Essential role of mitochondrial per- microtubule disassembly through TRPV1 activities meability transition in vanilloid receptor 1-dependent both on the plasma membrane and intracellular mem- cell death of sensory neurons. Mol Cell Neurosci 24, branes. Biochem Pharmacol 73, 1635–1645. 57–68. 43 Wang JP, Tseng CS, Sun SP, Chen YS, Tsai CR & 57 Kim SR, Kim SU, Oh U & Jin BK (2006) Transient Hsu MF (2005) Capsaicin stimulates the non-store- receptor potential vanilloid subtype 1 mediates micro- operated Ca2+ entry but inhibits the store-operated glial cell death in vivo and in vitro via Ca2+ -mediated

FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS 4695 TRP channels and cytoskeleton regulate each other C. Goswami and T. Hucho

mitochondrial damage and cytochrome c release. 71 Alessandri-Haber N, Yeh JJ, Boyd AE, Parada CA, J Immunol 177, 4322–4329. Chen X, Reichling DB & Levine JD (2003) Hypotonic- 58 Sańchez AM, Sańchez MG, Malagarie-Cazenave S, ity induces TRPV4-mediated nociception in rat. Neuron Olea N & Dıáz-Laviada I (2006) Induction of apopto- 39, 497–511. sis in prostate tumor PC-3 cells and inhibition of xeno- 72 Alessandri-Haber N, Dina OA, Yeh JJ, Parada CA, graft prostate tumor growth by the vanilloid capsaicin. Reichling DB & Levine JD (2004) Transient receptor Apoptosis 11, 89–99. potential vanilloid 4 is essential in chemotherapy- 59 Amantini C, Mosca M, Nabissi M, Lucciarini R, induced neuropathic pain in the rat. J Neurosci 24, Caprodossi S, Arcella A, Giangaspero F & Santoni G 4444–4452. (2007) Capsaicin-induced apoptosis of glioma cells is 73 Becker D, Blase C, Bereiter-Hahn J & Jendrach M mediated by TRPV1 vanilloid receptor and requires (2005) TRPV4 exhibits a functional role in cell-volume p38 MAPK activation. J Neurochem 102, 977–990. regulation. J Cell Sci 118, 2435–2440. 60 Waning J, Vriens J, Owsianik G, Stuwe L, Mally S, 74 Liu X, Bandyopadhyay B, Nakamoto T, Singh B, Lied- Fabian A, Frippiat C, Nilius B & Schwab A (2007) A tke W, Melvin JE & Ambudkar I (2006) A role for novel function of capsaicin-sensitive TRPV1 channels: AQP5 in activation of TRPV4 by hypotonicity: con- involvement in cell migration. Cell Calcium 42, 17–25. certed involvement of AQP5 and TRPV4 in regulation 61 Jin K, Xie L, Kim SH, Parmentier-Batteur S, Sun Y, of cell volume recovery. J Biol Chem 281, 15485–15495. Mao XO, Childs J & Greenberg DA (2004) Defective 75 Ramadass R, Becker D, Jendrach M & Bereiter-Hahn adult neurogenesis in CB1 cannabinoid receptor knock- J (2007) Spectrally and spatially resolved fluorescence out mice. Mol Pharmacol 66, 204–208. lifetime imaging in living cells: TRPV4-microfilament 62 Funakoshi K, Nakano M, Atobe Y, Goris RC, interactions. Arch Biochem Biophy 463, 27–36. Kadota T & Yazama F (2006) Differential develop- 76 Suzuki M, Hirao A & Mizuno A (2003) Microtubule- ment of TRPV1-expressing sensory nerves in peripheral associated protein 7 increases the membrane expression organs. Cell Tissue Res 323, 27–41. of transient receptor potential vanilloid 4 (TRPV4). 63 Ahmad FJ, Hughey J, Wittmann T, Hyman A, Grea- J Biol Chem 278, 51448–51453. ser M & Baas PW (2000) Motor proteins regulate force 77 Bollimuntha S, Cornatzer E & Singh BB (2005) Plasma interactions between microtubules and microfilaments membrane localization and function of TRPC1 is in the axon. Nat Cell Biol 2, 276–280. dependent on its interaction with beta-tubulin in retinal 64 Ahmad FJ & Baas PW (2001) Force generation by epithelium cells. Vis Neurosci 22, 163–170. cytoskeletal motor proteins as a regulator of axonal 78 Greka A, Navarro B, Oancea E, Duggan A & Clap- elongation and retraction. Trends Cell Biol 11, 244– ham DE (2003) TRPC5 is a regulator of hippocampal 249. neurite length and growth cone morphology. Nat Neu- 65 Basu S & Srivastava P (2005) Immunological role of rosci 6, 837–845. neuronal receptor vanilloid receptor 1 expressed on 79 Moore TM, Brough GH, Babal P, Kelly JJ, Li M & dendritic cells. Proc Natl Acad Sci USA 102, 5120– Stevens T (1998) Store-operated calcium entry pro- 5125. motes shape change in pulmonary endothelial cells 66 Schwab A, Nechyporuk-Zloy V, Fabian A & Stock C expressing Trp1. Am J Physiol 275, L574–L582. (2007) Cells move when ions and water flow. Pflugers 80 Shin JB, Adams D, Paukert M, Siba M, Sidi S, Levin Arch 453, 421–432. M, Gillespie PG & Gru¨nder S (2005) Xenopus TRPN1 67 Gomez T (2005) Neurobiology: channels for pathfind- (NOMPC) localizes to microtubule-based cilia in epi- ing. Nature 434, 835–838. thelial cells, including inner-ear hair cells. Proc Natl 68 Ramsey IS, Delling M & Clapham DE (2006) An Acad Sci USA 102, 12572–12577. introduction to TRP channels. Annu Rev Physiol 68, 81 Wu D, Huang W, Richardson PM, Priestley JV & Liu 619–647. M (2008) TRPC4 in rat dorsal root ganglion neurons 69 Maccarrone M, Barboni B, Paradisi A, Bernabo` N, is increased after nerve injury and is necessary for Gasperi V, Pistilli MG, Fezza F, Lucidi P & Mattioli neurite outgrowth. J Biol Chem 283, 416–426. M (2005) Characterization of the endocannabinoid sys- 82 Shim S, Goh EL, Ge S, Sailor K, Yuan JP, Roderick tem in boar spermatozoa and implications for sperm HL, Bootman MD, Worley PF, Song H & Ming GL capacitation and acrosome reaction. J Cell Sci 118, (2005) XTRPC1-dependent chemotropic guidance of 4393–4404. neuronal growth cones. Nat Neurosci 8, 730–735. 70 Watanabe H, Davis JB, Smart D, Jerman JC, Smith 83 Wang GX & Poo MM (2005) Requirement of TRPC GD, Hayes P, Vriens J, Cairns W, Wissenbach U, Pre- channels in netrin-1-induced chemotropic turning of nen J et al. (2002) Activation of TRPV4 channels nerve growth cones. Nature 434, 898–904. (hVRL-2 ⁄ mTRP12) by phorbol derivatives. J Biol 84 Li Y, Jia YC, Cui K, Li N, Zheng ZY, Wang YZ & Chem 277, 13569–13577. Yuan XB (2005) Essential role of TRPC channels in

4696 FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS C. Goswami and T. Hucho TRP channels and cytoskeleton regulate each other

the guidance of nerve growth cones by brain-derived requires activation of the phototransduction cascade. neurotrophic factor. Nature 434, 894–898. J Cell Sci 119, 2592–2603. 85 Wen Z, Han L, Bamburg JR, Shim S, Ming GL & 99 Clark K, Langeslag M, van Leeuwen B, Ran L, Ryaza- Zheng JQ (2007) BMP gradients steer nerve growth nov AG, Figdor CG, Moolenaar WH, Jalink K & van cones by a balancing act of LIM kinase and Slingshot Leeuwen FN (2006) TRPM7, a novel regulator of phosphatase on ADF ⁄ cofilin. J Cell Biol 178, 107–119. actomyosin contractility and cell adhesion. EMBO J 86 Rosado JA & Sage SO (2001) Activation of store-med- 25, 290–301. iated calcium entry by secretion-like coupling between 100 Clark K, Middelbeek J, Morrice NA, Figdor CG, the inositol 1,4,5-trisphosphate receptor type II and Lasonder E & van Leeuwen FN (2008) Massive auto- human transient receptor potential (hTrp1) channels in phosphorylation of the Ser ⁄ Thr-rich domain controls human platelets. Biochem J 356, 191–198. protein kinase activity of TRPM6 and TRPM7. PLoS 87 Rosado JA & Sage SO (2000) A role for the actin cyto- ONE 3, e1876. skeleton in the initiation and maintenance of store- 101 Loudon RP, Silver LD, Yee HF Jr & Gallo G (2006) mediated calcium entry in human platelets. Trends RhoA-kinase and myosin II are required for the main- Cardiovasc Med 10, 327–332. tenance of growth cone polarity and guidance by nerve 88 Itagaki K, Kannan KB, Singh BB & Hauser CJ (2004) growth factor. J Neurobiol 66, 847–867. Cytoskeletal reorganization internalizes multiple tran- 102 Medeiros NA, Burnette DT & Forscher P (2006) Myo- sient receptor potential channels and blocks calcium sin II functions in actin-bundle turnover in neuronal entry into human neutrophils. J Immunol 172, 601–607. growth cones. Nat Cell Biol 8, 215–226. 89 Otsuguro KI, Tang J, Tang Y, Xiao R, Freichel M, 103 Les Erickson F, Corsa AC, Dose AC & Burnside B Tsvilovskyy V, Ito S, Flockerzi V, Zhu MX & Zholos (2003) Localization of a class III myosin to filopodia AV (2008) Isoform-specific inhibition of TRPC4 chan- tips in transfected HeLa cells requires an actin-binding nel by phosphatidylinositol 4,5-bisphosphate. J Biol site in its tail domain. Mol Biol Cell 14, 4173–4180. Chem 283, 10026–10036. 104 Bridgman PC, Dave S, Asnes CF, Tullio AN & Adel- 90 Lemonnier L, Trebak M, Lievremont JP, Bird GS & stein RS (2001) Myosin IIB is required for growth cone Putney JW Jr (2006) Protection of TRPC7 cation motility. J Neurosci 21, 6159–6169. channels from calcium inhibition by closely associated 105 Bridgman PC & Elkin LL (2000) Axonal myosins. SERCA pumps. FASEB J 20, 503–505. J Neurocytol 29, 831–841. 91 Redowicz MJ (2002) Myosins and pathology: genetics 106 Berg JS, Derfler BH, Pennisi CM, Corey DP & Cheney and biology. Acta Biochim Pol 49, 789–804. RE (2000) Myosin-X, a novel myosin with pleckstrin 92 Libby RT & Steel KP (2000) The roles of unconven- homology domains, associates with regions of dynamic tional myosins in hearing and deafness. Essays Biochem actin. J Cell Sci 113, 3439–3451. 35, 159–174. 107 Berg JS & Cheney RE (2002) Myosin-X is an uncon- 93 Grimm C, Cuajungco MP, van Aken AF, Schnee M, ventional myosin that undergoes intrafilopodial motil- Jo¨rs S, Kros CJ, Ricci AJ & Heller S (2007) A ity. Nat Cell Biol 4, 246–250. helix-breaking mutation in TRPML3 leads to constit- 108 Sousa AD, Berg JS, Robertson BW, Meeker RB & utive activity underlying deafness in the varitint- Cheney RE (2006) Myo10 in brain: developmental waddler mouse. Proc Natl Acad Sci USA 104, regulation, identification of a headless isoform and 19583–19588. dynamics in neurons. J Cell Sci 119, 184–194. 94 Tabuchi K, Suzuki M, Mizuno A & Hara A (2005) 109 Sousa AD & Cheney RE (2005) Myosin-X: a molecu- Hearing impairment in TRPV4 knockout mice. Neuro- lar motor at the cell’s fingertips. Trends Cell Biol 15, sci Lett 382, 304–308. 533–539. 95 Sidi S, Friedrich RW & Nicolson T (2003) NompC 110 Bohil AB, Robertson BW & Cheney RE (2006) TRP channel required for vertebrate sensory hair cell Myosin-X is a molecular motor that functions in mechanotransduction. Science 301, 96–99. filopodia formation. Proc Natl Acad Sci USA 103, 96 Di Palma F, Belyantseva IA, Kim HJ, Vogt TF, 12411–12416. Kachar B & Noben-Trauth K (2002) Mutations in 111 Bennett RD, Mauer AS & Strehler EE (2007) Calmod- Mcoln3 associated with deafness and pigmentation ulin-like protein increases filopodia-dependent cell defects in varitint-waddler (Va) mice. Proc Natl Acad motility via up-regulation of myosin-10. J Biol Chem Sci USA 99, 14994–14999. 282, 3205–3212. 97 Nilius B, Voets T & Peters J (2005) TRP channels in 112 Belyantseva IA, Boger ET & Friedman TB (2003) disease. Sci STKE 295, re8. Myosin XVa localizes to the tips of inner ear sensory 98 Meyer NE, Joel-Almagor T, Frechter S, Minke B & cell stereocilia and is essential for staircase formation Huber A (2006) Subcellular translocation of the eGFP- of the hair bundle. Proc Natl Acad Sci USA 100, tagged TRPL channel in Drosophila photoreceptors 13958–13963.

FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS 4697 TRP channels and cytoskeleton regulate each other C. Goswami and T. Hucho

113 Kuwahara K, Wang Y, McAnally J, Richardson JA, 127 Li Q, Montalbetti N, Wu Y, Ramos A, Raychowdhury Bassel-Duby R, Hill JA & Olson EN (2006) TRPC6 MK, Chen XZ & Cantiello HF (2006) Polycystin-2 fulfills a calcineurin signaling circuit during pathologic cation channel function is under the control of micro- cardiac remodeling. J Clin Invest 116, 3114–31126. tubular structures in primary cilia of renal epithelial 114 Lishko PV, Procko E, Jin X, Phelps CB & Gaudet R cells. J Biol Chem 281, 37566–37575. (2007) The ankyrin repeats of TRPV1 bind multiple 128 Li Q, Dai XQ, Shen PY, Wu Y, Long W, Chen CX, ligands and modulate channel sensitivity. Neuron 54, Hussain Z, Wang S & Chen XZ (2007) Direct binding 905–918. of alpha-actinin enhances TRPP3 channel activity. 115 Mandadi S, Numazaki M, Tominaga M, Bhat MB, J Neurochem 103, 2391–2400. Armati PJ & Roufogalis BD (2004) Activation of pro- 129 Nilius B, Owsianik G, Voets T & Peters JA (2007) tein kinase C reverses capsaicin-induced calcium-depen- Transient receptor potential cation channels in disease. dent desensitization of TRPV1 ion channels. Cell Physiol Rev 87, 165–217. Calcium 35, 471–478. 130 Polomano RC & Bennett GJ (2001) Chemotherapy- 116 Mohapatra DP & Nau C (2005) Regulation of evoked painful peripheral neuropathy. Pain Med 2, Ca2+-dependent desensitization in the vanilloid recep- 8–14. tor TRPV1 by calcineurin and cAMP-dependent 131 Quasthoff S & Hartung HP (2002) Chemotherapy- protein kinase. J Biol Chem 280, 13424–13432. induced peripheral neuropathy. J Neurol 249, 9–17. 117 Mohapatra DP & Nau C (2003) Desensitization of 132 Hudes GR, Greenberg R, Krigel RL, Fox S, Scher R, capsaicin-activated currents in the vanilloid receptor Litwin S, Watts P, Speicher L, Tew K & Comis R TRPV1 is decreased by the cyclic AMP-dependent pro- (1992) Phase II study of estramustine and vinblastine, tein kinase pathway. J Biol Chem 278, 50080–50090. two microtubule inhibitors, in hormone-refractory 118 Zhu MX (2005) Multiple roles of calmodulin and other prostate cancer. J Clin Oncol 10, 1754–1761. Ca2+ -binding proteins in the functional regulation of 133 Topp KS, Tanner KD & Levine JD (2000) Damage to TRP channels. Pflugers Arch 451, 105–115. the cytoskeleton of large diameter sensory neurons and 119 Lambers TT, Weidema AF, Nilius B, Hoenderop JG myelinated axons in vincristine-induced painful periph- & Bindels RJ (2004) Regulation of the mouse epithelial eral neuropathy in the rat. J Comp Neurol 424, 563–576. Ca2+ channel TRPV6 by the Ca2+ -sensor calmodulin. 134 Tanner KD, Levine JD & Topp KS (1998) Microtu- J Biol Chem 279, 28855–28861. bule disorientation and axonal swelling in unmyeli- 120 Rosenbaum T, Gordon-Shaag A, Munari M & Gor- nated sensory axons during vincristine-induced painful don SE (2004) Ca2+ ⁄ calmodulin modulates TRPV1 neuropathy in rat. J Comp Neurol 395, 481–492. activation by capsaicin. J Gen Physiol 123, 53–62. 135 Dina OA, McCarter GC, de Coupade C & Levine JD 121 Strotmann R, Schultz G & Plant TD (2003) (2003) Role of the sensory neuron cytoskeleton in Ca2+-dependent potentiation of the nonselective cation second messenger signaling for inflammatory pain. channel TRPV4 is mediated by a C-terminal calmodu- Neuron 39, 613–624. lin binding site. J Biol Chem 278, 26541–26549. 136 Bhave G & Gereau RW 4th (2003) Growing pains: the 122 Watanabe H, Vriens J, Suh SH, Benham CD, Droog- cytoskeleton as a critical regulator of pain plasticity. mans G & Nilius B (2002) Heat-evoked activation of Neuron 39, 577–579. TRPV4 channels in a HEK293 cell expression system 137 Takanari H, Yosida T, Morita J, Izutsu K & Ito T and in native mouse aorta endothelial cells. J Biol (1990) Instability of pleomorphic tubulin paracrystals Chem 277, 47044–47051. artificially induced by Vinca alkaloids in tissue-cultured 123 Chung MK, Lee H & Caterina MJ (2003) Warm tem- cells. Biol Cell 70, 83–90. peratures activate TRPV4 in mouse 308 keratinocytes. 138 Foss M, Wilcox BW, Alsop GB & Zhang D (2008) J Biol Chem 278, 32037–32046. Taxol crystals can masquerade as stabilized microtu- 124 Cho H, Shin J, Shin CY, Lee SY & Oh U (2002) bules. PLoS ONE 3, e1476. Mechanosensitive ion channels in cultured sensory 139 Elie-Caille C, Severin F, Helenius J, Howard J, Muller neurons of neonatal rats. J Neurosci 22, 1238–1247. DJ & Hyman AA (2007) Straight GDP-tubulin proto- 125 Montalbetti N, Li Q, Timpanaro GA, Gonza´lez-Perrett filaments form in the presence of taxol. Curr Biol 17, S, Dai XQ, Chen XZ & Cantiello HF (2005) Cytoskel- 1765–1770. etal regulation of calcium-permeable cation channels in 140 Asai H, Ozaki N, Shinoda M, Nagamine K, Tohnai I, the human syncytiotrophoblast: role of gelsolin. Ueda M & Sugiura Y (2005) Heat and mechanical J Physiol 566, 309–325. hyperalgesia in mice model of cancer pain. Pain 117, 126 Montalbetti N, Li Q, Wu Y, Chen XZ & Cantiello HF 19–29. (2007) Polycystin-2 cation channel function in the 141 Prevarskaya N, Flourakis M, Bidaux G, Thebault S & human syncytiotrophoblast is regulated by microtubu- Skryma R (2007) Differential role of TRP channels in lar structures. J Physiol 579, 717–728. prostate cancer. Biochem Soc Trans 35, 133–135.

4698 FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS C. Goswami and T. Hucho TRP channels and cytoskeleton regulate each other

142 Bo¨dding M (2007) TRP proteins and cancer. Cell 150 Puntambekar P, Van Buren J, Raisinghani M, Premku- Signal 19, 617–624. mar LS & Ramkumar V (2004) Direct interaction of 143 Hartel M, Di Mola FF, Salvaggi F, Mascetta G, adenosine with the TRPV1 channel protein. J Neurosci Wente MN, Felix K, Giese NA, Hinz U, Di Sebasti- 24, 3663–3671. ano P, Buchler MW et al. (2006) Vanilloids in pancreas 151 Reilly CA, Johansen ME, Lanza DL, Lee J, Lim JO & cancer: potential for chemotherapy and pain manage- Yost GS (2005) Calcium-dependent and independent ment. Gut 55, 519–528. mechanisms of capsaicin receptor (TRPV1)-mediated 144 Ghilardi JR, Rohrich H, Lindsay TH, Sevcik MA, cytokine production and cell death in human Schwei MJ, Kubota K, Halvorson KG, Poblete J, Cha- bronchial epithelial cells. J Biochem Mol Toxicol 19, plan SR, Dubin AE et al. (2005) Selective blockade of 266–275. the capsaicin receptor TRPV1 attenuates bone cancer 152 Contassot E, Wilmotte R, Tenan M, Belkouch MC, pain. J Neurosci 25, 3126–3131. Schnuriger V, de Tribolet N, Burkhardt K & Dietrich 145 Vriens J, Janssens A, Prenen J, Nilius B & Wondergem PY (2004) Arachidonylethanolamide induces apoptosis R (2004) TRPV channels and modulation by hepato- of human glioma cells through vanilloid receptor-1. cyte growth factor ⁄ scatter factor in human hepatoblas- J Neuropathol Exp Neurol 63, 956–963. toma (HepG2) cells. Cell Calcium 36, 19–28. 153 Movsesyan VA, Stoica BA, Yakovlev AG, Knoblach 146 Sanchez MG, Sanchez AM, Collado B, Malagarie- SM, Lea PM 4th, Cernak I, Vink R & Faden AI Cazenave S, Olea N, Carmena MJ, Prieto JC & Diaz- (2004) Anandamide-induced cell death in primary Laviada II (2005) Expression of the transient receptor neuronal cultures: role of calpain and caspase potential vanilloid 1 (TRPV1) in LNCaP and PC-3 pathways. Cell Death Differ 11, 1121–1132. prostate cancer cells and in human prostate tissue. Eur 154 Razavi R, Chan Y, Afifiyan FN, Liu XJ, Wan X, J Pharmacol 515, 20–27. Yantha J, Tsui H, Tang L, Tsai S, Santamaria P et al. 147 Jancso´G, Karcsu´S, Kira´ly E, Szebeni A, To´th L, (2006) TRPV1+ sensory neurons control beta cell Baćsy E, Joo´F&Pa´rducz A (1984) Neurotoxin stress and islet inflammation in autoimmune diabetes. induced nerve cell degeneration: possible involvement Cell 127, 1123–1135. of calcium. Brain Res 295, 211–216. 155 McMahon SB, Lewin G & Bloom SR (1991) The con- 148 Karai L, Brown DC, Mannes AJ, Connelly ST, Brown sequences of long-term topical capsaicin application in J, Gandal M, Wellisch OM, Neubert JK, Olah Z & the rat. Pain 44, 301–310. Iadarola MJ (2004) Deletion of vanilloid receptor 156 Kiselyov K, Soyombo A & Muallem S (2007) TRP- 1-expressing primary afferent neurons for pain control. pathies. J Physiol 578, 641–653. J Clin Invest 113, 1344–1352. 157 Stephens RE (1986) Membrane tubulin. Biol Cell 57, 149 Kim SR, Lee daY, Chung ES, Oh UT, Kim SU & Jin 95–109. BK (2005) Transient receptor potential vanilloid 158 Gu C, Zhou W, Puthenveedu MA, Xu M, Jan YN & subtype 1 mediates cell death of mesencephalic dopa- Jan LY (2006) The microtubule plus-end tracking pro- minergic neurons in vivo and in vitro. J Neurosci 25, tein EB1 is required for Kv1 voltage-gated K+ channel 662–671. axonal targeting. Neuron 52, 803–816.

FEBS Journal 275 (2008) 4684–4699 ª 2008 The Authors Journal compilation ª 2008 FEBS 4699