DOCSLIB.ORG

Rallying the Exocyst As an Autophagy Scaffold

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Rallying the Exocyst As an Autophagy Scaffold View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector PreviewsLeading Edge Rallying the Exocyst as an Autophagy Scaffold Jean-Claude Farre´ 1 and Suresh Subramani1,* 1Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA *Correspondence: [email protected] DOI 10.1016/j.cell.2011.01.005 Protein scaffolds coordinate the assembly of many multicomponent signaling complexes. Bode- mann et al. (2011) now show that the exocyst, a protein complex involved in tethering transport vesi- cles to the plasma membrane, provides an assembly and activation platform for components of the autophagy machinery via a process requiring the GTPase RalB. Macroautophagy (henceforth referred to Autophagosome formation consists of ates with Atg5 and Atg12, autophagy as autophagy) is a cellular degradation three steps: nucleation, expansion, and proteins involved in the ubiquitin-like pathway for the clearance of damaged fusion of the isolation membrane. Each system, cementing the association or superfluous proteins and organelles step involves a specific set of protein between the autophagy machinery and (Yang and Klionsky, 2010). Despite its complexes. The ULK (Unc-51-like kinase) the exocyst. importance in cellular homeostasis and and PI3K (phosphatidylinositol-3 kinase) Given the association between auto- in immunity against pathogens and complexes are most important for nucle- phagy and exocyst components and the despite accumulating knowledge re- ation, whereas the ubiquitin-like (Ubl) fact that the small GTPases RalA and garding the autophagy machinery itself, conjugation system and the mAtg9 (mam- RalB mobilize exocyst assembly (Moska- the early regulatory signals that activate malian autophagy-related gene 9) cycling lenko et al., 2002, 2003), the authors next autophagy are unknown. Furthermore, complex, which is involved in transit of inquire whether RalA and RalB also play several gaps remain in our understanding mAtg9 to and from the isolation mem- a role in autophagy. Indeed, Bodemann of how distinct autophagy complexes brane, facilitate expansion and closure et al. show convincingly that activation of assemble and collaborate (Mehrpour of the isolation membrane (Mehrpour RalB, but not RalA, in cervical cancer and et al., 2010). Bodemann et al. (2011) now et al., 2010). epithelial cell lines is necessary for auto- identify some of the early regulatory and The exocyst, a hetero-octameric phagy. They find that competitive in- assembly steps, revealing a role for the complex containing the proteins Sec3, hibitors of RalB inhibit the induction of exocyst, a complex that regulates post- Sec5, Sec6, Sec8, Sec10, Sec15, autophagy during starvation, whereas Golgi protein traffic. The authors demon- Exo70, and Exo84 (recently renamed constitutively activated forms of RalB stim- strate that nutrient deprivation, a condition EXOC1-EXOC8) is involved in the post- ulate autophagy even under nutrient-rich that promotes autophagy, activates the Golgi trafficking and tethering of vesicles conditions. Thus, RalB is both necessary Ras-like small GTPase RalB, which then to the plasma membrane (He and Guo, and sufficient for activation of autophagy. engages the effector protein and exocyst 2009; Munson and Novick, 2006). New RalB and its related partner RalA coop- component Exo84. This interaction pro- evidence implicating a role for the exocyst erate in mitogen-induced signaling during motes the assembly and activation of complex in signaling during pathogen oncogenic transformation by Ras. RalA is the autophagy complex using the exocyst infection (Chien et al., 2006) led the required to bypass normal restraints on as an assembly scaffold. authors to screen for proteins interacting cell proliferation, whereas RalB bypasses During metabolic stress, including star- with the exocyst subunit, Sec3. Using normal restraints on cell survival (Chien vation, autophagy promotes the degrada- a high-throughput yeast two-hybrid et al., 2006). Tumor cells have higher tion of cytoplasmic components by the screen, the authors found that both nega- levels of RalB, and cells depleted of lysosome, and the recycling of their tive and positive regulators of autophagy RalB exhibit survival defects (Bodemann constituents promotes cell survival (Mehr- interact with Sec3. The interactors include and White, 2008). These observations pour et al., 2010; Yang and Klionsky, Rubicon (RUN domain and cysteine-rich may be explained, in part, by the finding 2010). Autophagy involves formation of domain containing), an inhibitor of au- that RalB promotes cell survival during an isolation membrane, which elongates tophagy, as well as Atg14L, a component starvation by inducing autophagy. and fuses to form a double-membrane of the PI3K complex, and FIP200, part of Interestingly, the authors characterize vesicle called an autophagosome. The the ULK complex. Indeed, the authors two complexes containing both exocyst autophagosome encloses cytoplasmic find that several exocyst subunits (Sec3, and autophagy components: an auto- cargoes for delivery by fusion to the endo- Sec5, and Exo84) coimmunoprecipitate phagy-active and autophagy-inactive some or lysosome, eventually forming an with Rubicon and Atg14L. Additionally, complex. The RalB-Exo84 complex con- autolysosome. the core exocyst subunit, Sec8, associ- tains functional ULK and PI3K complexes, 172 Cell 144, January 21, 2011 ª2011 Elsevier Inc. suggesting that this complex both general autophagy and is active during starvation- the selective autophagic induced autophagy. In degradation of bacteria. contrast, upon inhibition of Together, the data are consis- RalB signaling, Rubicon, an tent with the idea that the exo- inhibitor of autophagy, asso- cyst functions as a scaffold for ciates with Exo84. The Sec5- the core autophagy machinery ULK-PI3K complex correlates in mammalian cells. with the inactive autophagy Earlier work showed that state and is more abundant RalB competes with phos- under nutrient-rich condi- phatidylinositol 3,4,5-tri- tions. These observations led sphosphate (PIP3) for binding the authors to propose a to the pleckstrin homology model for the activation of (PH) domain of Exo84 (Mos- autophagy (Figure 1). They kalenko et al., 2003). It is suggest that assembly of the therefore exciting to hypothe- ULK and PI3K complexes on size that the binding of RalB Exo84 triggers autophagy by to Exo84 may trigger the generating an autophagy- movement of the complex active complex. In contrast, from a PIP3-enriched environ- interaction between these ment, such as the plasma complexes and Sec5 creates membrane or recycling endo- an autophagy-inactive com- somes, to the autophago- plex that is either a preinitiation some assembly site. complex unable but poised to The precise mechanism trigger autophagy or is a signal linking the activities of the termination complex for the ULK and PI3K complexes to process. Consistent with this the elongation and completion model, endogenous mamma- Figure 1. A Model for Exocyst Function in Autophagy of the isolation membrane by Bodemann et al. (2011) provide evidence that the exocyst, a protein complex lian target of rapamycin involved in post-Golgi protein traffic, may function as a scaffold for the the Ubl and mAtg9 cycling complex 1 (mTORC1), which assembly of autophagy complexes. The authors suggest the following model complexes has been unclear inhibits autophagy through for activation of autophagy. Under nutrient-rich conditions, an exocyst sub- (Mehrpour et al., 2010). The complex containing the Sec5 protein associates with the Unc-51 like kinase inactivation of the ULK com- (ULK) and phosphatidylinositol-3 kinase (PI3K) complexes at the perinuclear direct interaction of these plex (Mehrpour et al., 2010), region forming an autophagy-inactive complex. Induction of autophagy (e.g., complexes with the exocyst is present only in the auto- in response to starvation) leads to the activation of the Ras-like small GTPase, complex may provide this RalB. The activated RalB interacts with the exocyst, promoting the replace- phagy-inactive complex. ment of Sec5 by another exocyst component, Exo84, and formation of an missing link. The work of Bod- The cellular localization of active autophagy complex that includes the ubiquitin-like (Ubl) conjugation emann and colleagues shows complex components under system and the ubiquitin-like molecule LC3. This autophagy-active complex that all of these complexes different conditions suggests localizes in cytosolic dots that could correspond to the isolation membrane. assemble on a common scaf- The Exo84 exocyst subcomplex may bring together complexes of the core that the transition from an autophagic machinery or facilitate their concerted action. The exact subunit fold, a recurring theme ex- autophagy-inactive to an compositions of the autophagy-inactive and autophagy-active exocyst sub- ploited by other signaling autophagy-active complex complexes remain unknown. PI3P, phosphatidylinositol 3-phosphate; PI, systems (Shaw and Filbert, phosphatidylinositol. WIPI-1 is a WD40 repeat autophagy protein that inter- may involve a change in local- acts with phosphoinositides such as PI3P. 2009),suggesting that the exo- ization. Bodemann et al. find cyst may coordinate molecular that, under nutrient-rich con- events in autophagy. ditions, RalB associates with The primary known function an exocyst subcomplex containing PI3K complex). These results
Load more

Recommended publications
  • Localization of Ralb Signaling at Endomembrane Compartments and Its Modulation by Autophagy Received: 14 January 2019 Manish Kumar Singh1,2, Alexandre P
    www.nature.com/scientificreports Corrected: Publisher Correction OPEN Localization of RalB signaling at endomembrane compartments and its modulation by autophagy Received: 14 January 2019 Manish Kumar Singh1,2, Alexandre P. J. Martin1,2, Carine Jofre 3, Giulia Zago1,2, Accepted: 30 May 2019 Jacques Camonis1,2, Mathieu Coppey1,4 & Maria Carla Parrini1,2 Published online: 20 June 2019 The monomeric GTPase RalB controls crucial physiological processes, including autophagy and invasion, but it still remains unclear how this multi-functionality is achieved. Previously, we reported that the RalGEF (Guanine nucleotide Exchange Factor) RGL2 binds and activates RalB to promote invasion. Here we show that RGL2, a major activator of RalB, is also required for autophagy. Using a novel automated image analysis method, Endomapper, we quantifed the endogenous localization of the RGL2 activator and its substrate RalB at diferent endomembrane compartments, in an isogenic normal and Ras-transformed cell model. In both normal and Ras-transformed cells, we observed that RGL2 and RalB substantially localize at early and recycling endosomes, and to lesser extent at autophagosomes, but not at trans-Golgi. Interestingly the use of a FRET-based RalB biosensor indicated that RalB signaling is active at these endomembrane compartments at basal level in rich medium. Furthermore, induction of autophagy by nutrient starvation led to a considerable reduction of early and recycling endosomes, in contrast to the expected increase of autophagosomes, in both normal and Ras-transformed cells. However, autophagy mildly afected relative abundances of both RGL2 and RalB at early and recycling endosomes, and at autophagosomes. Interestingly, RalB activity increased at autophagosomes upon starvation in normal cells.
    [Show full text]
  • The Role of Rala and Ralb in Cancer Samuel C
    University of South Florida Scholar Commons Graduate Theses and Dissertations Graduate School 4-7-2008 The Role of RalA and RalB in Cancer Samuel C. Falsetti University of South Florida Follow this and additional works at: https://scholarcommons.usf.edu/etd Part of the American Studies Commons Scholar Commons Citation Falsetti, Samuel C., "The Role of RalA and RalB in Cancer" (2008). Graduate Theses and Dissertations. https://scholarcommons.usf.edu/etd/232 This Dissertation is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. The Role of RalA and RalB in Cancer By Samuel C. Falsetti A dissertation submitted in partial fulfillment Of the requirements for the degree of Doctor of Philosophy Department of Molecular Medicine College of Medicine University of South Florida Major Professor: Saïd M. Sebti, Ph.D. Larry P. Solomonson, Ph.D. Gloria C. Ferreira, Ph.D. Srikumar Chellapan, Ph.D. Gary Reuther, Ph.D. Douglas Cress, Ph.D. Date of Approval: April 7th, 2008 Keywords: Ras, RACK1, Geranylgeranyltransferase I inhibitors, ovarian cancer, proteomics © Copyright 2008, Samuel C. Falsetti Dedication This thesis is dedicated to my greatest supporter, my wife. Without her loving advice and patience none of this would be possible. Acknowledgments I would like to extend my sincere gratitude to my wife, Nicole. She is the most inspirational person in my life and I am honored to be with her; in truth, this degree ought to come with two names printed on it.
    [Show full text]
  • Redefining the Specificity of Phosphoinositide-Binding by Human
    bioRxiv preprint doi: https://doi.org/10.1101/2020.06.20.163253; this version posted June 21, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC 4.0 International license. Redefining the specificity of phosphoinositide-binding by human PH domain-containing proteins Nilmani Singh1†, Adriana Reyes-Ordoñez1†, Michael A. Compagnone1, Jesus F. Moreno Castillo1, Benjamin J. Leslie2, Taekjip Ha2,3,4,5, Jie Chen1* 1Department of Cell & Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801; 2Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205; 3Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218; 4Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205; 5Howard Hughes Medical Institute, Baltimore, MD 21205, USA †These authors contributed equally to this work. *Correspondence: [email protected]. bioRxiv preprint doi: https://doi.org/10.1101/2020.06.20.163253; this version posted June 21, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC 4.0 International license. ABSTRACT Pleckstrin homology (PH) domains are presumed to bind phosphoinositides (PIPs), but specific interaction with and regulation by PIPs for most PH domain-containing proteins are unclear. Here we employed a single-molecule pulldown assay to study interactions of lipid vesicles with full-length proteins in mammalian whole cell lysates.
    [Show full text]
  • Association of Gene Ontology Categories with Decay Rate for Hepg2 Experiments These Tables Show Details for All Gene Ontology Categories
    Supplementary Table 1: Association of Gene Ontology Categories with Decay Rate for HepG2 Experiments These tables show details for all Gene Ontology categories. Inferences for manual classification scheme shown at the bottom. Those categories used in Figure 1A are highlighted in bold. Standard Deviations are shown in parentheses. P-values less than 1E-20 are indicated with a "0". Rate r (hour^-1) Half-life < 2hr. Decay % GO Number Category Name Probe Sets Group Non-Group Distribution p-value In-Group Non-Group Representation p-value GO:0006350 transcription 1523 0.221 (0.009) 0.127 (0.002) FASTER 0 13.1 (0.4) 4.5 (0.1) OVER 0 GO:0006351 transcription, DNA-dependent 1498 0.220 (0.009) 0.127 (0.002) FASTER 0 13.0 (0.4) 4.5 (0.1) OVER 0 GO:0006355 regulation of transcription, DNA-dependent 1163 0.230 (0.011) 0.128 (0.002) FASTER 5.00E-21 14.2 (0.5) 4.6 (0.1) OVER 0 GO:0006366 transcription from Pol II promoter 845 0.225 (0.012) 0.130 (0.002) FASTER 1.88E-14 13.0 (0.5) 4.8 (0.1) OVER 0 GO:0006139 nucleobase, nucleoside, nucleotide and nucleic acid metabolism3004 0.173 (0.006) 0.127 (0.002) FASTER 1.28E-12 8.4 (0.2) 4.5 (0.1) OVER 0 GO:0006357 regulation of transcription from Pol II promoter 487 0.231 (0.016) 0.132 (0.002) FASTER 6.05E-10 13.5 (0.6) 4.9 (0.1) OVER 0 GO:0008283 cell proliferation 625 0.189 (0.014) 0.132 (0.002) FASTER 1.95E-05 10.1 (0.6) 5.0 (0.1) OVER 1.50E-20 GO:0006513 monoubiquitination 36 0.305 (0.049) 0.134 (0.002) FASTER 2.69E-04 25.4 (4.4) 5.1 (0.1) OVER 2.04E-06 GO:0007050 cell cycle arrest 57 0.311 (0.054) 0.133 (0.002)
    [Show full text]
  • Targeting PH Domain Proteins for Cancer Therapy
    The Texas Medical Center Library DigitalCommons@TMC The University of Texas MD Anderson Cancer Center UTHealth Graduate School of The University of Texas MD Anderson Cancer Biomedical Sciences Dissertations and Theses Center UTHealth Graduate School of (Open Access) Biomedical Sciences 12-2018 Targeting PH domain proteins for cancer therapy Zhi Tan Follow this and additional works at: https://digitalcommons.library.tmc.edu/utgsbs_dissertations Part of the Bioinformatics Commons, Medicinal Chemistry and Pharmaceutics Commons, Neoplasms Commons, and the Pharmacology Commons Recommended Citation Tan, Zhi, "Targeting PH domain proteins for cancer therapy" (2018). The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences Dissertations and Theses (Open Access). 910. https://digitalcommons.library.tmc.edu/utgsbs_dissertations/910 This Dissertation (PhD) is brought to you for free and open access by the The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences at DigitalCommons@TMC. It has been accepted for inclusion in The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences Dissertations and Theses (Open Access) by an authorized administrator of DigitalCommons@TMC. For more information, please contact [email protected]. TARGETING PH DOMAIN PROTEINS FOR CANCER THERAPY by Zhi Tan Approval page APPROVED: _____________________________________________ Advisory Professor, Shuxing Zhang, Ph.D. _____________________________________________
    [Show full text]
  • A Compendium of Co-Regulated Protein Complexes in Breast Cancer Reveals Collateral Loss Events
    bioRxiv preprint doi: https://doi.org/10.1101/155333; this version posted June 26, 2017. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. A compendium of co-regulated protein complexes in breast cancer reveals collateral loss events Colm J. Ryan*1, Susan Kennedy1, Ilirjana Bajrami2, David Matallanas1, Christopher J. Lord2 1Systems Biology Ireland, School of Medicine, University College Dublin, Dublin 4, Ireland 2The Breast Cancer Now Toby Robins Breast Cancer Research Centre and CRUK Gene Function Laboratory, The Institute of Cancer Research, London, SW3 6JB, United Kingdom. * Correspondence: [email protected] Summary Protein complexes are responsible for the bulk of activities within the cell, but how their behavior and composition varies across tumors remains poorly understood. By combining proteomic profiles of breast tumors with a large-scale protein-protein interaction network, we have identified a set of 258 high-confidence protein complexes whose subunits have highly correlated protein abundance across tumor samples. We used this set to identify complexes that are reproducibly under- or over- expressed in specific breast cancer subtypes. We found that mutation or deletion of one subunit of a complex was often associated with a collateral reduction in protein expression of additional complex members. This collateral loss phenomenon was evident from proteomic, but not transcriptomic, profiles suggesting post- transcriptional control. Mutation of the tumor suppressor E-cadherin (CDH1) was associated with a collateral loss of members of the adherens junction complex, an effect we validated using an engineered model of E-cadherin loss.
    [Show full text]
  • Phosphorylation of Ralb Is Important for Bladder Cancer Cell Growth and Metastasis
    Published OnlineFirst October 12, 2010; DOI: 10.1158/0008-5472.CAN-10-0952 Published OnlineFirst on October 12, 2010 as 10.1158/0008-5472.CAN-10-0952 Therapeutics, Targets, and Chemical Biology Cancer Research Phosphorylation of RalB Is Important for Bladder Cancer Cell Growth and Metastasis Hong Wang1, Charles Owens1, Nidhi Chandra1, Mark R. Conaway2, David L. Brautigan3,4, and Dan Theodorescu5 Abstract RalA and RalB are monomeric G proteins that are 83% identical in amino acid sequence but have paralogue- specific effects on cell proliferation, metastasis, and apoptosis. Using in vitro kinase assays and phosphosite- specific antibodies, here we show phosphorylation of RalB by protein kinase C (PKC) and RalA by protein kinase A. We used mass spectrometry and site-directed mutagenesis to identify S198 as the primary PKC phosphorylation site in RalB. Phorbol ester [phorbol 12-myristate 13-acetate (PMA)] treatment of human blad- der carcinoma cells induced S198 phosphorylation of stably expressed FLAG-RalB as well as endogenous RalB. PMA treatment caused RalB translocation from the plasma membrane to perinuclear regions in a S198 phos- phorylation–dependent manner. Using RNA interference depletion of RalB followed by rescue with wild-type RalB or RalB(S198A) as well as overexpression of wild-type RalB or RalB(S198A) with and without PMA stimulation, we show that phosphorylation of RalB at S198 is necessary for actin cytoskeletal organization, anchorage-independent growth, cell migration, and experimental lung metastasis of T24 or UMUC3 human bladder cancer cells. In addition, UMUC3 cells transfected with a constitutively active RalB(G23V) exhibited enhanced subcutaneous tumor growth, whereas those transfected with phospho-deficient RalB(G23V-S198A) were indistinguishable from control cells.
    [Show full text]
  • Human Induced Pluripotent Stem Cell–Derived Podocytes Mature Into Vascularized Glomeruli Upon Experimental Transplantation
    BASIC RESEARCH www.jasn.org Human Induced Pluripotent Stem Cell–Derived Podocytes Mature into Vascularized Glomeruli upon Experimental Transplantation † Sazia Sharmin,* Atsuhiro Taguchi,* Yusuke Kaku,* Yasuhiro Yoshimura,* Tomoko Ohmori,* ‡ † ‡ Tetsushi Sakuma, Masashi Mukoyama, Takashi Yamamoto, Hidetake Kurihara,§ and | Ryuichi Nishinakamura* *Department of Kidney Development, Institute of Molecular Embryology and Genetics, and †Department of Nephrology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan; ‡Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Hiroshima, Japan; §Division of Anatomy, Juntendo University School of Medicine, Tokyo, Japan; and |Japan Science and Technology Agency, CREST, Kumamoto, Japan ABSTRACT Glomerular podocytes express proteins, such as nephrin, that constitute the slit diaphragm, thereby contributing to the filtration process in the kidney. Glomerular development has been analyzed mainly in mice, whereas analysis of human kidney development has been minimal because of limited access to embryonic kidneys. We previously reported the induction of three-dimensional primordial glomeruli from human induced pluripotent stem (iPS) cells. Here, using transcription activator–like effector nuclease-mediated homologous recombination, we generated human iPS cell lines that express green fluorescent protein (GFP) in the NPHS1 locus, which encodes nephrin, and we show that GFP expression facilitated accurate visualization of nephrin-positive podocyte formation in
    [Show full text]
  • The Small G-Protein Rala Promotes Progression and Metastasis of Triple- Negative Breast Cancer Katie A
    Thies et al. Breast Cancer Research (2021) 23:65 https://doi.org/10.1186/s13058-021-01438-3 RESEARCH ARTICLE Open Access The small G-protein RalA promotes progression and metastasis of triple- negative breast cancer Katie A. Thies1,2, Matthew W. Cole1,2, Rachel E. Schafer1,2, Jonathan M. Spehar1,2, Dillon S. Richardson1,2, Sarah A. Steck1,2, Manjusri Das1,2, Arthur W. Lian1,2, Alo Ray1,2, Reena Shakya1,3, Sue E. Knoblaugh4, Cynthia D. Timmers5,6, Michael C. Ostrowski5,7, Arnab Chakravarti1,2, Gina M. Sizemore1,2 and Steven T. Sizemore1,2* Abstract Background: Breast cancer (BC) is the most common cancer in women and the leading cause of cancer-associated mortality in women. In particular, triple-negative BC (TNBC) has the highest rate of mortality due in large part to the lack of targeted treatment options for this subtype. Thus, there is an urgent need to identify new molecular targets for TNBC treatment. RALA and RALB are small GTPases implicated in growth and metastasis of a variety of cancers, although little is known of their roles in BC. Methods: The necessity of RALA and RALB for TNBC tumor growth and metastasis were evaluated in vivo using orthotopic and tail-vein models. In vitro, 2D and 3D cell culture methods were used to evaluate the contributions of RALA and RALB during TNBC cell migration, invasion, and viability. The association between TNBC patient outcome and RALA and RALB expression was examined using publicly available gene expression data and patient tissue microarrays. Finally, small molecule inhibition of RALA and RALB was evaluated as a potential treatment strategy for TNBC in cell line and patient-derived xenograft (PDX) models.
    [Show full text]
  • Genetic Deletion of RALA and RALB Small Gtpases Reveals Redundant Functions in Development and Tumorigenesis
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Current Biology 22, 2063–2068, November 6, 2012 ª2012 Elsevier Ltd All rights reserved http://dx.doi.org/10.1016/j.cub.2012.09.013 Report Genetic Deletion of RALA and RALB Small GTPases Reveals Redundant Functions in Development and Tumorigenesis Pascal Peschard,1 Afshan McCarthy,1 (Figures 1A and 1B) and loss of RALB proteins in tissues of Vale´rie Leblanc-Dominguez,1 Maggie Yeo,1 adult mice (Figure 1C). The expression of RALB proteins was Sabrina Guichard,1 Gordon Stamp,2 unchanged in Rala null cells and vice versa. and Christopher J. Marshall1,* To investigate the role of RALA in embryonic development, 1Oncogene Team, Division of Cancer Biology, Institute of we examined embryos from Rala+/2 intercrosses. Between Cancer Research, London SW3 6JB, UK embryonic day 10.5 (E10.5) and E19.5, we observed that 10 2Department of Histopathology, Royal Marsden Hospital, out of 33 of the Rala null embryos displayed exencephaly London SW3 6JJ, UK (Figures 1E and 1F), a condition caused by a failure of closure of the neural tube along the hindbrain region [15]. We also observed exencephaly in Rala null embryos generated from Summary a gene-trap embryonic stem (ES) clone (Figures 1G and S1E– S1I). To examine whether RALA and RALB have overlapping RAL small GTPases, encoded by the Rala and Ralb genes, functions in neural tube closure, we generated compound are members of the RAS superfamily of small GTPases and mutants: 14 of 14 Rala2/2;Ralb+/2 embryos displayed a severe can act as downstream effectors of RAS [1].
    [Show full text]
  • Targeting the Ras-Ral Effector Pathway for Cancer Treatment
    TARGETING THE RAS-RAL EFFECTOR PATHWAY FOR CANCER TREATMENT Leanna R. Gentry A dissertation submitted to the faculty at the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Pharmacology. Chapel Hill 2015 Approved by: Adrienne Cox Channing Der Lee Graves Klaus Hahn Gary Johnson ©2015 Leanna R. Gentry ALL RIGHTS RESERVED ii ABSTRACT LEANNA R. GENTRY: Targeting the Ras-Ral effector pathway for cancer treatment (Under the direction of Channing J. Der) The RAS oncogene is the most frequently mutated gene in human cancers, and this activated Ras oncoprotein has been shown to be required for both cancer initiation and maintenance. Great strides have been made in understanding Ras signaling in cancer since the discovery of its involvement in human cancers in 1982, with numerous Ras effector pathways and modes of Ras regulation having been identified as contributing to Ras-driven oncogenesis. However, there has been limited success in developing strategies for therapeutically targeting Ras-driven oncogenesis. One effort that has gained popularity in recent years is the inhibition of Ras effector signaling. The Ral (Ras-like) small GTPases, discovered shortly after Ras in an attempt to identify RAS-related genes, are activated downstream of Ras by Ral guanine nucleotide exchange factors (RalGEFs). The Ral family members have since emerged as critical regulators of key cellular processes and, importantly, have been characterized as playing a role in tumorigenesis and invasion of multiple cancer types. Interestingly, divergent roles for RalA and RalB are often observed in within a cancer.
    [Show full text]
  • Exocyst Inactivation in Urothelial Cells Disrupts Autophagy and Activates Non-Canonical
    bioRxiv preprint doi: https://doi.org/10.1101/2021.07.05.451173; this version posted July 5, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Exocyst Inactivation in Urothelial Cells Disrupts Autophagy and Activates non-canonical NF-κB Michael A. Ortega1,2, Ross K. Villiger2, Malia Harrison-Chau2, Suzanna Lieu2, Kadee-Kalia Tamashiro2, Amanda J. Lee2,3, Brent A. Fujimoto2, Geetika Y. Patwardhan2, Joshua Kepler2 & Ben Fogelgren*2 1 Center for Biomedical Research at The Queen’s Medical Center, Honolulu, Hawaii 96813; 2 Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii 96813; 3 Math and Sciences Department, Kapiolani Community College, Honolulu, Hawaii 96816. *Corresponding Author: Ben Fogelgren Email address: [email protected] Keywords: autophagy / exocyst / Fn14 / NF-κB / urothelium 1 bioRxiv preprint doi: https://doi.org/10.1101/2021.07.05.451173; this version posted July 5, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Abstract Ureter obstruction is a highly prevalent event during embryonic development and is a major cause of pediatric kidney disease. We have reported that ureteric bud-specific ablation of the exocyst Exoc5 subunit in late-murine gestation results in failure of urothelial stratification, cell death, and complete ureter obstruction. However, the mechanistic connection between disrupted exocyst activity, urothelial cell death, and subsequent ureter obstruction was unclear. Here, we report that inhibited urothelial stratification does not drive cell death during ureter development.
    [Show full text]