DOCSLIB.ORG

The SNARE Machinery in Mast Cell Secretion

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The SNARE Machinery in Mast Cell Secretion REVIEW ARTICLE published: 05 June 2012 doi: 10.3389/fimmu.2012.00143 The SNARE machinery in mast cell secretion Axel Lorentz 1*, Anja Baumann1, Joana Vitte 2,3 and Ulrich Blank 2,3* 1 Department of Nutritional Medicine, University of Hohenheim, Stuttgart, Germany 2 INSERM UMRS 699, Paris, France 3 Laboratoire d’Excellence Inflamex, Faculté de Médicine, Site Xavier Bichat, Université Paris-Diderot, Paris, France Edited by: Mast cells are known as inflammatory cells which exert their functions in allergic and ana- Marc Benhamou, Institut National de phylactic reactions by secretion of numerous inflammatory mediators. During an allergic la Santé et de la Recherche Médicale, ε France response, the high-affinity IgE receptor, Fc RI, becomes cross-linked by receptor-bound IgE Reviewed by: and antigen resulting in immediate release of pre-synthesized mediators – stored in gran- Marc Benhamou, Institut National de ules – as well as in de novo synthesis of various mediators like cytokines and chemokines. la Santé et de la Recherche Médicale, Soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptors (SNARE) France proteins were found to play a central role in regulating membrane fusion events during Laura Eugenia Velazquez, Institut National de la Santé et de la exocytosis. In addition, several accessory regulators like Munc13, Munc18, Rab GTPases, Recherche Médicale/Université Paris secretory carrier membrane proteins, complexins, or synaptotagmins were found to be 13, France involved in membrane fusion. In this review we summarize our current knowledge about *Correspondence: the SNARE machinery and its mechanism of action in mast cell secretion. Axel Lorentz, Department of Nutritional Medicine, University of Keywords: mast cell, exocytosis, SNARE proteins Hohenheim, Fruwirthstraße 12, D-70593 Stuttgart, Germany. e-mail: axel.lorentz@ uni-hohenheim.de; Ulrich Blank, INSERM UMRS 699, Université Paris-Diderot, Faculté de Médecine Site Bichat, 16, rue Henri Huchard, F-75870 Paris CEDEX 18, France. e-mail: [email protected] INTRODUCTION mast cell specific proteases or through carrier vesicles emanating Mast cells are tissue-localized cells that upon activation release a from the Golgi including a large array of cytokines/chemokines whole variety of inflammatory mediators (Blank and Rivera, 2004; (Blank and Rivera, 2004; Sagi-Eisenberg, 2007). Considerable Rivera and Gilfillan, 2006). When released, their role is to pro- advances have been made in the understanding of the molecu- tect the body against infectious agents, injury or stress, however, lar machinery involved in vesicular secretion. In this review we inappropriate or chronic production may also have harmful con- provide an overview of the current knowledge on the mecha- sequences and engender inflammatory diseases (Bischoff, 2007; nisms of mast cell exocytosis as well as our current ideas about Kalesnikoff and Galli,2008;Abraham and St John,2010). Mast cells its mechanisms of regulation. are best-known for the role they play in allergic diseases after stim- ulation through IgE bound to high-affinity IgE receptors. However, CHARACTERISTICS OF MAST CELL EXOCYTOSIS recent years have made clear their general role both in protec- Transport of vesicles and exocytosis of mediators are cellular tive and disease-promoting inflammatory responses that involve processes that occur in all eukaryotic cells. Newly synthesized stimulation through a wide array of surface-expressed receptors mediators must be translocated into the endoplasmic reticulum including IgG Fc receptors, different types of G protein-coupled and then transported to the Golgi apparatus, where secretory car- receptors, Toll-like receptors, etc. (Bischoff, 2007; Kalesnikoff and goes are sorted into a variety of transport carriers for delivery to Galli, 2008; Abraham and St John, 2010; Beghdadi et al., 2011). their final destinations (Glick and Nakano, 2009). Some secretory While initial therapeutic strategies aiming to restrict mast cell cells including mast cells are capable of regulated exocytosis (Lacy activation largely focused on blocking the activation of the IgE and Stow, 2011). They store a wide range of factors and immune receptor and its early signaling events, targeting the late signaling mediators in pre-formed secretory granules (SG). Like in other steps has become a suitable alternative strategy. The latter approach hematopoietic cells with SG these are dual-function organelles would block the consequences of activation by many different containing lysosomal hydrolases such as β-hexosaminidase and receptor types converging into the same secretory pathways. cathepsin-D as found in all lysosomes as well as specific secre- With the exception of lipid-derived mediators that are synthe- tory inflammatory products (Stinchcombe and Griffiths, 2007). sized at the plasma membrane, mast cells secrete their mediators They are therefore often called secretory lysosomes to underline either by a process called degranulation from sources pre-stored in the close connection between endosomal/lysosomal and secretory cytoplasmic granules including for example histamine and certain compartments. Functionally, secretory lysosomes are unusual in www.frontiersin.org June 2012 | Volume 3 | Article 143 | 1 Lorentz et al. Mast cell secretory machinery that they serve both as a degradative and as a secretory compart- SNARE PROTEINS IN DEGRANULATION ment (Blott and Griffiths, 2002). Upon activation mast cells release The fusion between vesicles or the plasma membrane is not a a high amount of granule contents (Blank and Rivera,2004). Mem- spontaneous event. It requires a specific set of proteins called brane fusion, necessary for the stimulus-coupled release of granule Soluble N-ethylmaleimide-sensitive factor attachment protein recep- contents, requires that lipid molecules leave their bilayer orien- tors (SNAREs) that are highly conserved in all eukaryotes (Sudhof tation to merge two lipid bilayers (Cohen and Melikyan, 2004). and Rothman, 2009; Sudhof and Rizo, 2011). They were initially In neurons, where each vesicle interacts independently with the discovered by several independent approaches involving yeast plasma membrane, exocytosis is coupled to rapid endocytosis and genetics and biochemical purification procedures from synaptic regeneration of SG within milliseconds until seconds. In contrast, membranes and by the ability to bind soluble N-ethylmaleimide- mast cells are capable of releasing high amounts of their gran- sensitive factor (NSF)-attachment proteins, which are adapters ular content in response to a single stimulatory event, a process that connect the fusion machinery to the NSF ATPase (Novick called degranulation, and the regeneration of a granule can take et al., 1980; Bennett and Scheller, 1993; Sollner et al., 1993). The up to 72 h (Galli et al., 1984; Gandhi and Stevens, 2003; Blank SNARE machinery of membrane fusion involves different sets of and Rivera, 2004). A resting human intestinal mast cell and a proteins that lie on opposing membranes. They enable fusion by mast cell following activation induced degranulation are shown forming a highly stable tetrameric trans-SNARE complex through in Figure 1. Unlike neurons, mast cells SG can form channels four conserved 60–70 aa SNARE motifs (Sutton et al., 1998). Dis- by fusing with each other. This so-called compound exocytosis sociation of this complex is the energy-requiring step in fusion can either occur in a sequential or in a multivesicular manner. and is mediated by the NSF ATPase (Hanson et al., 1997). A typ- In sequential exocytosis, vesicles initially fuse with the plasma ical trans-SNARE complex at the plasma membrane includes a membrane followed by the fusion of underlying next vesicles vesicular SNARE (v-SNARE) such as vesicle associated membrane with the first vesicle. In multivesicular exocytosis, vesicles fuse protein (VAMP) that pairs with two target membrane SNAREs with each other before interacting with the plasma membrane (t-SNAREs) such as a Syntaxin (STX) molecule and synaptosome- (Alvarez de Toledo and Fernandez, 1990). Compound exocyto- associated protein of 23 (ubiquitous) or 25 (neuronal) kDa (SNAP- sis enables mast cells to discharge their contents very efficiently 23/25) containing two SNARE motifs (Sutton et al., 1998). To take (Pickett and Edwardson, 2006). In response to some stimuli, mast into account that v-SNAREs can also be found on the target mem- cells show also so-called piecemeal degranulation characterized by brane,for example in the case of homotypic vesicle fusion,SNAREs gradual loss of granule contents without detectable granule fusion. have also been classified structurally into R-SNAREs (correspond- Thus, piecemeal degranulation allows discharge of discrete pack- ing with few exceptions to v-SNAREs) based on a central R residue ets of granule-associated components without granule exocytosis in the 0 layer of the classical four-helix-bundle of the SNARE (Dvorak, 2005). While mast cell mediator release occurs typically, complex and Q-SNAREs with a central Q residue (Hong, 2005). although not exclusively, multi-directionally, other cell types of the Trans-SNARE complex, generally consists of either one v-SNARE immune system such as cytotoxic T cells or natural killer (NK) cells and two or three t-SNAREs or one R-SNARE and two or three Q- use secretory lysosomes to deliver proteins involved in their effec- SNAREs. Figure 2A illustrates SNARE complex formation catalyz- tor functions at the immune synapse in a uni-directional,polarized
Load more

Recommended publications
  • Supplementary Table 4
    Li et al. mir-30d in human cancer Table S4. The probe list down-regulated in MDA-MB-231 cells by mir-30d mimic transfection Gene Probe Gene symbol Description Row set 27758 8119801 ABCC10 ATP-binding cassette, sub-family C (CFTR/MRP), member 10 15497 8101675 ABCG2 ATP-binding cassette, sub-family G (WHITE), member 2 18536 8158725 ABL1 c-abl oncogene 1, receptor tyrosine kinase 21232 8058591 ACADL acyl-Coenzyme A dehydrogenase, long chain 12466 7936028 ACTR1A ARP1 actin-related protein 1 homolog A, centractin alpha (yeast) 18102 8056005 ACVR1 activin A receptor, type I 20790 8115490 ADAM19 ADAM metallopeptidase domain 19 (meltrin beta) 15688 7979904 ADAM21 ADAM metallopeptidase domain 21 14937 8054254 AFF3 AF4/FMR2 family, member 3 23560 8121277 AIM1 absent in melanoma 1 20209 7921434 AIM2 absent in melanoma 2 19272 8136336 AKR1B10 aldo-keto reductase family 1, member B10 (aldose reductase) 18013 7954777 ALG10 asparagine-linked glycosylation 10, alpha-1,2-glucosyltransferase homolog (S. pombe) 30049 7954789 ALG10B asparagine-linked glycosylation 10, alpha-1,2-glucosyltransferase homolog B (yeast) 28807 7962579 AMIGO2 adhesion molecule with Ig-like domain 2 5576 8112596 ANKRA2 ankyrin repeat, family A (RFXANK-like), 2 23414 7922121 ANKRD36BL1 ankyrin repeat domain 36B-like 1 (pseudogene) 29782 8098246 ANXA10 annexin A10 22609 8030470 AP2A1 adaptor-related protein complex 2, alpha 1 subunit 14426 8107421 AP3S1 adaptor-related protein complex 3, sigma 1 subunit 12042 8099760 ARAP2 ArfGAP with RhoGAP domain, ankyrin repeat and PH domain 2 30227 8059854 ARL4C ADP-ribosylation factor-like 4C 32785 8143766 ARP11 actin-related Arp11 6497 8052125 ASB3 ankyrin repeat and SOCS box-containing 3 24269 8128592 ATG5 ATG5 autophagy related 5 homolog (S.
    [Show full text]
  • Syntaxin 2 Promotes Colorectal Cancer Growth by Increasing the Secretion
    Journal of Cancer 2021, Vol. 12 2050 Ivyspring International Publisher Journal of Cancer 2021; 12(7): 2050-2058. doi: 10.7150/jca.51494 Research Paper Syntaxin 2 promotes colorectal cancer growth by increasing the secretion of exosomes Yongxia Wang1,2,3, Yongzhen Li1,2,3, Hong Zhou2, Xinlai Qian1,2,3, Yuhan Hu1,2,3 1. Department of Pathology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang 453003, Henan, China. 2. Department of Pathology, Third Affiliated Hospital of Xinxiang Medical University, Xinxiang 453003, Henan, China. 3. Henan Provincial Key Laboratory of Molecular Tumor Pathology, Henan, Xinxiang, China. Corresponding authors: Xinlai Qian: Department of Pathology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang 453003, Henan, China. Yuhan Hu: Department of Pathology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang 453003, Henan, China. © The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/). See http://ivyspring.com/terms for full terms and conditions. Received: 2020.08.04; Accepted: 2020.12.10; Published: 2021.02.02 Abstract Background: Colorectal cancer (CRC) is one of the most common cancers with high mortality worldwide. Uncontrolled growth is an important hallmark of CRC. However, the mechanisms are poorly understood. Methods: Syntaxin 2 (STX2) expression was analyzed in 160 cases of paraffin-embedded CRC tissue by immunohistochemistry, in 10 cases of fresh CRC tissue by western blot, and in 2 public databases. Gain- and loss-of-function analyses were used to investigate the biological function of STX2 in CRC growth.
    [Show full text]
  • Title Stx2 Induces Differential Gene Expression by Activating Several Pathways and Disturbs Circadian Rhythm Genes in the Proximal Tubule
    bioRxiv preprint doi: https://doi.org/10.1101/2021.06.11.448004; this version posted June 11, 2021. 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-ND 4.0 International license. Title Stx2 induces differential gene expression by activating several pathways and disturbs circadian rhythm genes in the proximal tubule Fumiko Obata*, Ryo Ozuru, Takahiro Tsuji, Takashi Matsuba and Jun Fujii Division of Bacteriology, Department of Microbiology and Immunology, Faculty of Medicine, Tottori University, 86 Nishicho, Yonago, Tottori, 683-8503 Japan. *correspondence author Keywords Shiga toxin type 2 (Stx2), renal proximal tubule, mouse, human renal proximal tubular epithelial cell (RPTEC), microarray, circadian rhythm Abstract (1)Background: Shiga toxin-producing Escherichia coli (STEC) causes proximal tubular defects in the kidney. However, factors altered by Shiga toxin (Stx) within the proximal tubules are yet to be shown. (2) Methods: We determined Stx receptor Gb3 in murine and human kidneys and confirmed the receptor expression in the proximal tubules. Stx2-injected mouse kidney tissues and Stx2-treated human primary renal proximal tubular epithelial cell (RPTEC) were collected, and microarray analysis was performed. (3) Results: We compared murine kidney and RPTEC arrays and selected common 58 genes that are differentially expressed vs. control (0 h, no toxin-treated). We found that the most highly expressed gene was GDF15, which may be involved in Stx2-induced weight loss. Genes associated with previously reported Stx2 activities such as src kinase Yes phosphorylation pathway activation, unfolded protein response (UPR) and ribotoxic stress response (RSR) showed differential expressions.
    [Show full text]
  • Toxigenic Properties and Stx Phage Characterization of Escherichia Coli
    Rahman et al. BMC Microbiology (2018) 18:98 https://doi.org/10.1186/s12866-018-1235-3 RESEARCH ARTICLE Open Access Toxigenic properties and stx phage characterization of Escherichia coli O157 isolated from animal sources in a developing country setting Mahdia Rahman1, Ashikun Nabi1,2, Md Asadulghani1, Shah M. Faruque1,3 and Mohammad Aminul Islam1* Abstract Background: In many Asian countries including Bangladesh E. coli O157 are prevalent in animal reservoirs and in the food chain, but the incidence of human infection due to E. coli O157 is rare. One of the reasons could be inability of the organism from animal origin to produce sufficient amount of Shiga toxin (Stx), which is the main virulence factor associated with the severe sequelae of infection. This study aimed to fill out this knowledge gap by investigating the toxigenic properties and characteristics of stx phage of E. coli O157 isolated from animal sources in Bangladesh. Results: We analysed 47 stx2 positive E. coli O157 of food/animal origin for stx2 gene variants, Shiga toxin production, presence of other virulence genes, stx phage insertion sites, presence of genes associated with functionality of stx phages (Q933 and Q21)andstx2 upstream region. Of the 47 isolates, 46 were positive for both stx2a and stx2d while the remaining isolate was positive for stx2d only. Reverse Passive Latex Agglutination assay (RPLA) showed that 42/47 isolates produced little or no toxin, while 5 isolates produced a high titre of toxin (64 to 128). 39/47 isolates were positive for the Toxin Non-Producing (TNP) specific regions in the stx2 promoter.
    [Show full text]
  • Shiga Toxin E. Coli Detection Differentiation Implications for Food
    SL440 Shiga Toxin-Producing Escherichia coli: Detection, Differentiation, and Implications for Food Safety1 William J. Zaragoza, Max Teplitski, and Clifton K. Fagerquist2 Introduction for the effective detection of the Shiga-toxin-producing pathogens in a variety of food matrices. Shiga toxin is a protein found within the genome of a type of virus called a bacteriophage. These bacteriophages can There are two types of Shiga toxins—Shiga toxin 1 (Stx1) integrate into the genomes of the bacterium E. coli, giving and Shiga toxin 2 (Stx2). Stx1 is composed of several rise to Shiga toxin-producing E. coli (STEC). Even though subtypes knows as Stx1a, Stx1c, and Stx1d. Stx2 has seven most E. coli are benign or even beneficial (“commensal”) subtypes: a–g. Strains carrying all of the Stx1 subtypes affect members of our gut microbial communities, strains of E. humans, though they are less potent than that of Stx2. Stx2 coli carrying Shiga-toxin encoding genes (as well as other subtypes a,c, and d are frequently associated with human virulence determinants) are highly pathogenic in humans illness, while the other subtypes affect different animals. and other animals. When mammals ingest these bacteria, Subtypes Stx2b and Stx2e affect neonatal piglets, while STECs can undergo phage-driven lysis and deliver these target hosts for Stx2f and Stx2g subtypes are not currently toxins to mammalian guts. The Shiga toxin consists of an known (Fuller et al. 2011). Stx2f was originally isolated A subunit and 5 identical B subunits. The B subunits are from feral pigeons (Schmidt et al. 2000), and Stx2g was involved in binding to gut epithelial cells.
    [Show full text]
  • Tamoxifen Blocks Retrograde Trafficking of Shiga Toxin 1 and 2
    Published Online: 26 June, 2019 | Supp Info: http://doi.org/10.26508/lsa.201900439 Downloaded from life-science-alliance.org on 26 September, 2021 Research Article Tamoxifen blocks retrograde trafficking of Shiga toxin 1 and 2 and protects against lethal toxicosis Andrey S Selyunin1, Steven Hutchens1, Stanton F McHardy2, Somshuvra Mukhopadhyay1 Shiga toxin 1 (STx1) and 2 (STx2), produced by Shiga toxin– retrograde intracellular trafficking (4, 5, 6, 7, 8, 9). Retrograde transport producing Escherichia coli, cause lethal untreatable disease. The of both toxins involves, sequentially, endocytosis, transit through toxins invade cells via retrograde trafficking. Direct early early endosomes and the Golgi apparatus, and delivery to the en- endosome-to-Golgi transport allows the toxins to evade degra- doplasmic reticulum from where the A subunit is translocated to the dative late endosomes. Blocking toxin trafficking, particularly at cytosol (5, 6, 7, 8, 9). Direct transport from early endosomes to the Golgi the early endosome-to-Golgi step, is appealing, but transport is critical as it allows the toxins to evade late endosomes where mechanisms of the more disease-relevant STx2 are unclear. Using proteolytic enzymes are active (5, 6, 7, 8, 9). As STx1 and STx2 must data from a genome-wide siRNA screen, we discovered that traffic to the cytosol to induce cytotoxicity, blocking toxin transport in disruption of the fusion of late endosomes, but not autopha- general, and at the early endosome-to-Golgi step in particular, has gosomes, with lysosomes blocked the early endosome-to-Golgi emerged as a promising therapeutic strategy (5, 6, 10, 11). As an ex- transport of STx2.
    [Show full text]
  • Retrograde Trafficking of AB5 Toxins: Mechanisms to Therapeutics
    J Mol Med DOI 10.1007/s00109-013-1048-7 REVIEW Retrograde trafficking of AB5 toxins: mechanisms to therapeutics Somshuvra Mukhopadhyay & Adam D. Linstedt Received: 1 April 2013 /Revised: 23 April 2013 /Accepted: 24 April 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Bacterial AB5 toxins are a clinically relevant class and epidemic diarrhea; and pertussis toxin (PTx), which is the of exotoxins that include several well-known members such causative agent for whooping cough [1, 2]. Each year, infec- as Shiga, cholera, and pertussis toxins. Infections with toxin- tions with these toxin-producing bacteria affect millions of producing bacteria cause devastating human diseases that individuals and cause more than a million deaths [1]. affect millions of individuals each year and have no definitive AB5 toxins are so-called because they are formed by the medical treatment. The molecular targets of AB5 toxins reside association of a single A subunit with a pentameric B subunit in the cytosol of infected cells, and the toxins reach the cytosol (Fig. 1)[1, 2]. The toxins exert their cytotoxic effect by by trafficking through the retrograde membrane transport altering the activity of specific molecular targets in the cytosol pathway that avoids degradative late endosomes and lyso- of infected cells. STx blocks protein synthesis by removing a somes. Focusing on Shiga toxin as the archetype member, single adenine residue from the 28S ribosomal RNA, and CTx we review recent advances in understanding the molecular and PTx increase cAMP levels by ADP-ribosylating the Gsα mechanisms involved in the retrograde trafficking of AB5 or Giα components of heterotrimeric G proteins, respectively toxins and highlight how these basic science advances are [1, 2].
    [Show full text]
  • The Habc Domain of Syntaxin 3 Is a Ubiquitin Binding Domain
    www.nature.com/scientificreports OPEN The Habc domain of syntaxin 3 is a ubiquitin binding domain Adrian J. Giovannone1,6, Elena Reales1,2,3,6, Pallavi Bhattaram1,4, Sirpi Nackeeran1, Adam B. Monahan1, Rashid Syed1,5 & Thomas Weimbs1* Syntaxins are a family of membrane-anchored SNARE proteins that are essential components required for membrane fusion in eukaryotic intracellular membrane trafcking pathways. Syntaxins contain an N-terminal regulatory domain, termed the Habc domain that is not highly conserved at the primary sequence level but folds into a three-helix bundle that is structurally conserved among family members. The syntaxin Habc domain has previously been found to be structurally very similar to the GAT domain present in GGA family members and related proteins that are otherwise completely unrelated to syntaxins. Because the GAT domain has been found to be a ubiquitin binding domain we hypothesized that the Habc domain of syntaxins may also bind to ubiquitin. Here, we report that the Habc domain of syntaxin 3 (Stx3) indeed binds to monomeric ubiquitin with low afnity. This domain binds efciently to K63-linked poly-ubiquitin chains within a narrow range of chain lengths but not to K48-linked poly-ubiquitin chains. Other syntaxin family members also bind to K63-linked poly-ubiquitin chains but with diferent chain length specifcities. Molecular modeling suggests that residues of the GGA3-GAT domain known to be important for ionic and hydrophobic interactions with ubiquitin may have equivalent, conserved residues within the Habc domain of Stx3. We conclude that the syntaxin Habc domain and the GAT domain are both structurally and functionally related, and likely share a common ancestry despite sequence divergence.
    [Show full text]
  • Escherichia Coli Shiga Toxins and Gut Microbiota Interactions
    toxins Review Escherichia coli Shiga Toxins and Gut Microbiota Interactions Kyung-Soo Lee 1,2 , Yu-Jin Jeong 1,* and Moo-Seung Lee 1,2,* 1 Environmental Diseases Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Daejeon 34141, Korea; [email protected] 2 Department of Biomolecular Science, KRIBB School of Bioscience, Korea University of Science and Technology (UST), 127 Gajeong-ro, Yuseong-gu, Daejeon 34113, Korea * Correspondence: [email protected] (Y.-J.J.); [email protected] (M.-S.L.) Abstract: Escherichia coli (EHEC) and Shigella dysenteriae serotype 1 are enterohemorrhagic bacteria that induce hemorrhagic colitis. This, in turn, may result in potentially lethal complications, such as hemolytic uremic syndrome (HUS), which is characterized by thrombocytopenia, acute renal failure, and neurological abnormalities. Both species of bacteria produce Shiga toxins (Stxs), a phage-encoded exotoxin inhibiting protein synthesis in host cells that are primarily responsible for bacterial virulence. Although most studies have focused on the pathogenic roles of Stxs as harmful substances capable of inducing cell death and as proinflammatory factors that sensitize the host target organs to damage, less is known about the interface between the commensalism of bacterial communities and the pathogenicity of the toxins. The gut contains more species of bacteria than any other organ, providing pathogenic bacteria that colonize the gut with a greater number of opportunities to encounter other bacterial species. Notably, the presence in the intestines of pathogenic EHEC producing Stxs associated with severe illness may have compounding effects on the diversity of the indigenous bacteria and bacterial communities in the gut.
    [Show full text]
  • Murine Perinatal Beta Cell Proliferation and the Differentiation of Human Stem Cell Derived Insulin Expressing Cells Require NEUROD1
    Page 1 of 105 Diabetes Murine perinatal beta cell proliferation and the differentiation of human stem cell derived insulin expressing cells require NEUROD1 Anthony I. Romer,1,2 Ruth A. Singer1,3, Lina Sui2, Dieter Egli,2* and Lori Sussel1,4* 1Department of Genetics and Development, Columbia University, New York, NY 10032, USA 2Department of Pediatrics, Columbia University, New York, NY 10032, USA 3Integrated Program in Cellular, Molecular and Biomedical Studies, Columbia University, New York, NY 10032, USA 4Department of Pediatrics, University of Colorado Denver School of Medicine, Denver, CO 80045, USA *Co-Corresponding Authors Dieter Egli 1150 St. Nicholas Avenue New York, NY 10032 [email protected] Lori Sussel 1775 Aurora Ct. Aurora, CO 80045 [email protected] Word Count: Abstract= 149; Body= 4773 Total Paper Figures= 7, Total Supplemental Tables= 4, Total Supplemental Figures= 5 Diabetes Publish Ahead of Print, published online September 13, 2019 Diabetes Page 2 of 105 Abstract Inactivation of the β cell transcription factor NEUROD1 causes diabetes in mice and humans. In this study, we uncovered novel functions of Neurod1 during murine islet cell development and during the differentiation of human embryonic stem cells (HESCs) into insulin-producing cells. In mice, we determined that Neurod1 is required for perinatal proliferation of alpha and beta cells. Surprisingly, apoptosis only makes a minor contribution to beta cell loss when Neurod1 is deleted. Inactivation of NEUROD1 in HESCs severely impaired their differentiation from pancreatic progenitors into insulin expressing (HESC-beta) cells; however survival or proliferation was not affected at the time points analyzed. NEUROD1 was also required in HESC-beta cells for the full activation of an essential beta cell transcription factor network.
    [Show full text]
  • Antibiotic Therapy in the Treatment of E
    UNIVERSITY OF CINCINNATI Date:___________________ I, _________________________________________________________, hereby submit this work as part of the requirements for the degree of: in: It is entitled: This work and its defense approved by: Chair: _______________________________ _______________________________ _______________________________ _______________________________ _______________________________ Antibiotic Therapy in the Treatment of E. coli O157:H7. A dissertation submitted to the Division of Graduate Studies and Research of the University of Cincinnati In partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY (Ph.D.) In the Department of Molecular Genetics, Biochemistry, & Microbiology of the College of Medicine 2008 Colleen M. McGannon B.S., Ashland University, 2002 Committee Chair: Alison A. Weiss, Ph.D. Abstract Escherichia coli O157:H7 causes an estimated 73,000 of food borne illness annually. Varying levels of disease severity exist and include diarrhea, bloody diarrhea, and hemolytic uremic syndrome which can result in kidney damage or death. E. coli O157:H7 produces Shiga toxins 1 and/or 2, although it is Shiga toxin 2 that is linked to severe disease. Currently, a Shiga toxin-producing isolate will yield a positive diagnostic result, regardless of which Shiga toxin variant is produced. We have developed an ELISA that can differentiate between Shiga toxin 1 and Shiga toxin 2 in the presence of fecal material, and if used in the clinical setting, can increase the accuracy of prognosis for a patient infected with E. coli O157:H7. Epidemiological studies have suggested that antibiotics may be linked to HUS development. As such, we have completed an extensive study to determine which, if any, antibiotics are safe for the treatment of E.
    [Show full text]
  • How Alternative Splicing Affects Membrane-Trafficking Dynamics R
    © 2018. Published by The Company of Biologists Ltd | Journal of Cell Science (2018) 131, jcs216465. doi:10.1242/jcs.216465 REVIEW How alternative splicing affects membrane-trafficking dynamics R. Eric Blue1, Ennessa G. Curry1,*, Nichlas M. Engels1,*, Eunice Y. Lee1 and Jimena Giudice1,2,3,‡ ABSTRACT et al., 2012). Tissue-specific exons encode disordered segments The cell biology field has outstanding working knowledge of the within proteins that function in microtubule-based transport, fundamentals of membrane-trafficking pathways, which are of critical endocytosis and membrane deformation (Buljan et al., 2012; Ellis importance in health and disease. Current challenges include et al., 2012) (Box 1). understanding how trafficking pathways are fine-tuned for In humans, 90-95% of genes undergo alternative splicing, specialized tissue functions in vivo and during development. In expanding protein function beyond genetic diversity (Pan et al., parallel, the ENCODE project and numerous genetic studies have 2008; Wang et al., 2008). Splicing of intronic regions is regulated by revealed that alternative splicing regulates gene expression in tissues the strength of the splice sites; strong splice sites lead to constitutive and throughout development at a post-transcriptional level. This splicing, whereas weak splice sites are used in a context-dependent Review summarizes recent discoveries demonstrating that alternative manner (alternative splicing). Usage of weak splice sites is regulated splicing affects tissue specialization and membrane-trafficking by cis-regulatory sequences, trans-acting factors such as RNA- proteins during development, and examines how this regulation is binding proteins (RBPs) and epigenetics (Kornblihtt et al., 2013). altered in human disease. We first discuss how alternative splicing of Depending on splice site locations, different types of alternative clathrin, SNAREs and BAR-domain proteins influences endocytosis, splicing events are produced, which comprise insertion of secretion and membrane dynamics, respectively.
    [Show full text]