1
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An SJ, Anneken A, Xi Z, Choi C, Schlessinger J, Toomre D. Regulation of EGF-stimulated activation of the PI-3K/AKT pathway by exocyst-mediated exocytosis. Proc Natl Acad Sci U S A 2022; 119:e2208947119. [PMID: 36417441 PMCID: PMC9860279 DOI: 10.1073/pnas.2208947119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The phosphoinositide-3 kinase (PI-3K)/AKT cell survival pathway is an important pathway activated by EGFR signaling. Here we show, that in addition to previously described critical components of this pathway, i.e., the docking protein Gab1, the PI-3K/AKT pathway in epithelial cells is regulated by the exocyst complex, which is a vesicle tether that is essential for exocytosis. Using live-cell imaging, we demonstrate that PI(3,4,5)P3 levels fluctuate at the membrane on a minutes time scale and that these fluctuations are associated with local PI(3,4,5)P3 increases at sites where recycling vesicles undergo exocytic fusion. Supporting a role for exocytosis in PI(3,4,5)P3 generation, acute promotion of exocytosis by optogenetically driving exocyst-mediated vesicle tethering up-regulates PI(3,4,5)P3 production and AKT activation. Conversely, acute inhibition of exocytosis using Endosidin2, a small-molecule inhibitor of the exocyst subunit Exo70 (also designated EXOC7), or inhibition of exocyst function by siRNA-mediated knockdown of the exocyst subunit Sec15 (EXOC6), impairs PI(3,4,5)P3 production and AKT activation induced by EGF stimulation of epithelial cells. Moreover, prolonged inhibition of EGF signaling by EGFR tyrosine kinase inhibitors results in spontaneous reactivation of AKT without a concomitant relief of EGFR inhibition. However, this reactivation can be negated by acutely inhibiting the exocyst. These experiments demonstrate that exocyst-mediated exocytosis-by regulating PI(3,4,5)P3 levels at the plasma membrane-subserves activation of the PI-3K/AKT pathway by EGFR in epithelial cells.
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Affiliation(s)
- Seong J. An
- aDepartment of Cell Biology, Yale University School of Medicine, New Haven, CT06510
- bDepartment of Pharmacology, Yale University School of Medicine, New Haven, CT06510
- 2To whom correspondence may be addressed. or
| | - Alexander Anneken
- aDepartment of Cell Biology, Yale University School of Medicine, New Haven, CT06510
| | - Zhiqun Xi
- aDepartment of Cell Biology, Yale University School of Medicine, New Haven, CT06510
| | - Changseon Choi
- aDepartment of Cell Biology, Yale University School of Medicine, New Haven, CT06510
| | - Joseph Schlessinger
- bDepartment of Pharmacology, Yale University School of Medicine, New Haven, CT06510
| | - Derek Toomre
- aDepartment of Cell Biology, Yale University School of Medicine, New Haven, CT06510
- 2To whom correspondence may be addressed. or
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2
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Pushpa K, Dagar S, Kumar H, Pathak D, Mylavarapu SVS. The exocyst complex regulates C. elegans germline stem cell proliferation by controlling membrane Notch levels. Development 2021; 148:271155. [PMID: 34338279 DOI: 10.1242/dev.196345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 06/30/2021] [Indexed: 11/20/2022]
Abstract
The conserved exocyst complex regulates plasma membrane-directed vesicle fusion in eukaryotes. However, its role in stem cell proliferation has not been reported. Germline stem cell (GSC) proliferation in the nematode Caenorhabditis elegans is regulated by conserved Notch signaling. Here, we reveal that the exocyst complex regulates C. elegans GSC proliferation by modulating Notch signaling cell autonomously. Notch membrane density is asymmetrically maintained on GSCs. Knockdown of exocyst complex subunits or of the exocyst-interacting GTPases Rab5 and Rab11 leads to Notch redistribution from the GSC-niche interface to the cytoplasm, suggesting defects in plasma membrane Notch deposition. The anterior polarity (aPar) protein Par6 is required for GSC proliferation, and for maintaining niche-facing membrane levels of Notch and the exocyst complex. The exocyst complex biochemically interacts with the aPar regulator Par5 (14-3-3ζ) and Notch in C. elegans and human cells. Exocyst components are required for Notch plasma membrane localization and signaling in mammalian cells. Our study uncovers a possibly conserved requirement of the exocyst complex in regulating GSC proliferation and in maintaining optimal membrane Notch levels.
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Affiliation(s)
- Kumari Pushpa
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Sunayana Dagar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha 751024, India
| | - Harsh Kumar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Diksha Pathak
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Sivaram V S Mylavarapu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha 751024, India.,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
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3
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Zuo X, Kwon SH, Janech MG, Dang Y, Lauzon SD, Fogelgren B, Polgar N, Lipschutz JH. Primary cilia and the exocyst are linked to urinary extracellular vesicle production and content. J Biol Chem 2019; 294:19099-19110. [PMID: 31694916 PMCID: PMC6916495 DOI: 10.1074/jbc.ra119.009297] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 10/29/2019] [Indexed: 12/13/2022] Open
Abstract
The recently proposed idea of "urocrine signaling" hypothesizes that small secreted extracellular vesicles (EVs) contain proteins that transmit signals to distant cells. However, the role of renal primary cilia in EV production and content is unclear. We previously showed that the exocyst, a highly conserved trafficking complex, is necessary for ciliogenesis; that it is present in human urinary EVs; that knockdown (KD) of exocyst complex component 5 (EXOC5), a central exocyst component, results in very short or absent cilia; and that human EXOC5 overexpression results in longer cilia. Here, we show that compared with control Madin-Darby canine kidney (MDCK) cells, EXOC5 overexpression increases and KD decreases EV numbers. Proteomic analyses of isolated EVs from EXOC5 control, KD, and EXOC5-overexpressing MDCK cells revealed significant alterations in protein composition. Using immunoblotting to specifically examine the expression levels of ADP-ribosylation factor 6 (ARF6) and EPS8-like 2 (EPS8L2) in EVs, we found that EXOC5 KD increases ARF6 levels and decreases EPS8L2 levels, and that EXOC5 overexpression increases EPS8L2. Knockout of intraflagellar transport 88 (IFT88) confirmed that the changes in EV number/content were due to cilia loss: similar to EXOC5, the IFT88 loss resulted in very short or absent cilia, decreased EV numbers, increased EV ARF6 levels, and decreased Eps8L2 levels compared with IFT88-rescued EVs. Compared with control animals, urine from proximal tubule-specific EXOC5-KO mice contained fewer EVs and had increased ARF6 levels. These results indicate that perturbations in exocyst and primary cilia affect EV number and protein content.
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Affiliation(s)
- Xiaofeng Zuo
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Sang-Ho Kwon
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia 30912
| | - Michael G Janech
- Department of Biology, College of Charleston, Charleston, South Carolina 29424
| | - Yujing Dang
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Steven D Lauzon
- Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Ben Fogelgren
- Department of Anatomy, Biochemistry, and Physiology, University of Hawaii at Manoa, Honolulu, Hawaii 96813
| | - Noemi Polgar
- Department of Anatomy, Biochemistry, and Physiology, University of Hawaii at Manoa, Honolulu, Hawaii 96813
| | - Joshua H Lipschutz
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425
- Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29425
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4
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Pruski M, Hu L, Yang C, Wang Y, Zhang JB, Zhang L, Huang Y, Rajnicek AM, St Clair D, McCaig CD, Lang B, Ding YQ. Roles for IFT172 and Primary Cilia in Cell Migration, Cell Division, and Neocortex Development. Front Cell Dev Biol 2019; 7:287. [PMID: 31850339 PMCID: PMC6890611 DOI: 10.3389/fcell.2019.00287] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 11/04/2019] [Indexed: 12/25/2022] Open
Abstract
The cilium of a cell translates varied extracellular cues into intracellular signals that control embryonic development and organ function. The dynamic maintenance of ciliary structure and function requires balanced bidirectional cargo transport involving intraflagellar transport (IFT) complexes. IFT172 is a member of the IFT complex B, and IFT172 mutation is associated with pathologies including short rib thoracic dysplasia, retinitis pigmentosa and Bardet-Biedl syndrome, but how it underpins these conditions is not clear. We used the WIM cell line, derived from embryonic fibroblasts of Wimple mice (carrying homozygous Leu1564Pro mutation in Ift172), to probe roles of Ift172 and primary cilia in cell behavior. WIM cells had ablated cilia and deficiencies in directed migration (electrotaxis), cell proliferation and intracellular signaling. Additionally, WIM cells displayed altered cell cycle progression, with increased numbers of chromatids, highlighting dysfunctional centrosome status. Exposure to a physiological electric field promoted a higher percentage of primary cilia in wild-type cells. Interestingly, in situ hybridization revealed an extensive and dynamic expression profile of Ift172 in both developing and adult mouse cortex. In vivo manipulation of Ift172 expression in germinal regions of embryonic mouse brains perturbed neural progenitor proliferation and radial migration of post-mitotic neurons, revealing a regulatory role of Ift172 in cerebral morphogenesis. Our data suggest that Ift172 regulates a range of fundamental biological processes, highlighting the pivotal roles of the primary cilium in cell physiology and brain development.
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Affiliation(s)
- Michal Pruski
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Mental Disorders, Changsha, China.,State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, Department of Anatomy and Neurobiology, Collaborative Innovation Centre for Brain Science, Tongji University School of Medicine, Shanghai, China.,School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Ling Hu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China.,School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Cuiping Yang
- Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, Department of Anatomy and Neurobiology, Collaborative Innovation Centre for Brain Science, Tongji University School of Medicine, Shanghai, China
| | - Yubing Wang
- Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, Department of Anatomy and Neurobiology, Collaborative Innovation Centre for Brain Science, Tongji University School of Medicine, Shanghai, China
| | - Jin-Bao Zhang
- Department of Histology and Embryology, Institute of Neuroscience, Wenzhou Medical University, Wenzhou, China
| | - Lei Zhang
- Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, Department of Anatomy and Neurobiology, Collaborative Innovation Centre for Brain Science, Tongji University School of Medicine, Shanghai, China.,School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Ying Huang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, Department of Anatomy and Neurobiology, Collaborative Innovation Centre for Brain Science, Tongji University School of Medicine, Shanghai, China.,School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Ann M Rajnicek
- School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - David St Clair
- School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Colin D McCaig
- School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Bing Lang
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Mental Disorders, Changsha, China.,School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Yu-Qiang Ding
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China.,Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, Department of Anatomy and Neurobiology, Collaborative Innovation Centre for Brain Science, Tongji University School of Medicine, Shanghai, China
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5
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Lipschutz JH. The role of the exocyst in renal ciliogenesis, cystogenesis, tubulogenesis, and development. Kidney Res Clin Pract 2019; 38:260-266. [PMID: 31284362 PMCID: PMC6727897 DOI: 10.23876/j.krcp.19.050] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 05/13/2019] [Accepted: 05/20/2019] [Indexed: 12/23/2022] Open
Abstract
The exocyst is a highly conserved eight-subunit protein complex (EXOC1–8) involved in the targeting and docking of exocytic vesicles translocating from the trans-Golgi network to various sites in renal cells. EXOC5 is a central exocyst component because it connects EXOC6, bound to the vesicles exiting the trans-Golgi network via the small GTPase RAB8, to the rest of the exocyst complex at the plasma membrane. In the kidney, the exocyst complex is involved in primary ciliognesis, cystogenesis, and tubulogenesis. The exocyst, and its regulators, have also been found in urinary extracellular vesicles, and may be centrally involved in urocrine signaling and repair following acute kidney injury. The exocyst is centrally involved in the development of other organs, including the eye, ear, and heart. The exocyst is regulated by many different small GTPases of the RHO, RAL, RAB, and ARF families. The small GTPases, and their guanine nucleotide exchange factors and GTPase-activating proteins, likely give the exocyst specificity of function. The recent development of a floxed Exoc5 mouse line will aid researchers in studying the role of the exocyst in multiple cells and organ types by allowing for tissue-specific knockout, in conjunction with Cre-driver mouse lines.
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Affiliation(s)
- Joshua H Lipschutz
- Department of Medicine, Medical University of South Carolina, Charleston, SC, USA.,Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC, USA
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6
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Mao Y, Tu R, Huang Y, Mao D, Yang Z, Lau PK, Wang J, Ni J, Guo Y, Xie T. The exocyst functions in niche cells to promote germline stem cell differentiation by directly controlling EGFR membrane trafficking. Development 2019; 146:dev.174615. [PMID: 31142545 DOI: 10.1242/dev.174615] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 05/14/2019] [Indexed: 12/31/2022]
Abstract
The niche controls stem cell self-renewal and differentiation in animal tissues. Although the exocyst is known to be important for protein membrane trafficking and secretion, its role in stem cells and niches has never been reported. Here, this study shows that the exocyst functions in the niche to promote germline stem cell (GSC) progeny differentiation in the Drosophila ovary by directly regulating EGFR membrane trafficking and signaling. Inactivation of exocyst components in inner germarial sheath cells, which form the differentiation niche, causes a severe GSC differentiation defect. The exocyst is required for maintaining niche cells and preventing BMP signaling in GSC progeny by promoting EGFR membrane targeting and signaling through direct association with EGFR. Finally, it is also required for EGFR membrane targeting, recycling and signaling in human cells. Therefore, this study reveals a novel function of the exocyst in niche cells to promote stem cell progeny differentiation by directly controlling EGFR membrane trafficking and signaling in vivo, and also provides important insight into how the niche controls stem cell progeny differentiation at the molecular level.
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Affiliation(s)
- Ying Mao
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Renjun Tu
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
| | - Yan Huang
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Decai Mao
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Zhihao Yang
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Pik Ki Lau
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jinhui Wang
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jianquan Ni
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Yusong Guo
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Ting Xie
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
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7
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Zuo X, Lobo G, Fulmer D, Guo L, Dang Y, Su Y, Ilatovskaya DV, Nihalani D, Rohrer B, Body SC, Norris RA, Lipschutz JH. The exocyst acting through the primary cilium is necessary for renal ciliogenesis, cystogenesis, and tubulogenesis. J Biol Chem 2019; 294:6710-6718. [PMID: 30824539 DOI: 10.1074/jbc.ra118.006527] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 02/25/2019] [Indexed: 11/06/2022] Open
Abstract
The exocyst is a highly conserved protein complex found in most eukaryotic cells and is associated with many functions, including protein translocation in the endoplasmic reticulum, vesicular basolateral targeting, and ciliogenesis in the kidney. To investigate the exocyst functions, here we exchanged proline for alanine in the highly conserved VXPX ciliary targeting motif of EXOC5 (exocyst complex component 5), a central exocyst gene/protein, and generated stable EXOC5 ciliary targeting sequence-mutated (EXOC5CTS-m) Madin-Darby canine kidney (MDCK) cells. The EXOC5CTS-m protein was stable and could bind other members of the exocyst complex. Culturing stable control, EXOC5-overexpressing (OE), Exoc5-knockdown (KD), and EXOC5CTS-m MDCK cells on Transwell filters, we found that primary ciliogenesis is increased in EXOC5 OE cells and inhibited in Exoc5-KD and EXOC5CTS-m cells. Growing cells in collagen gels until the cyst stage, we noted that EXOC5-OE cells form mature cysts with single lumens more rapidly than control cysts, whereas Exoc5-KD and EXOC5CTS-m MDCK cells failed to form mature cysts. Adding hepatocyte growth factor to induce tubulogenesis, we observed that EXOC5-OE cell cysts form tubules more efficiently than control MDCK cell cysts, EXOC5CTS-m MDCK cell cysts form significantly fewer tubules than control cell cysts, and Exoc5-KD cysts did not undergo tubulogenesis. Finally, we show that EXOC5 mRNA almost completely rescues the ciliary phenotypes in exoc5-mutant zebrafish, unlike the EXOC5CTS-m mRNA, which could not efficiently rescue the phenotypes. Taken together, these results indicate that the exocyst, acting through the primary cilium, is necessary for renal ciliogenesis, cystogenesis, and tubulogenesis.
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Affiliation(s)
| | - Glenn Lobo
- From the Departments of Medicine.,Ophthalmology, and
| | - Diana Fulmer
- From the Departments of Medicine.,Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Lilong Guo
- From the Departments of Medicine.,Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina 29425
| | | | | | | | | | | | - Simon C Body
- the Department of Anesthesiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Russell A Norris
- From the Departments of Medicine.,Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Joshua H Lipschutz
- From the Departments of Medicine, .,the Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401, and
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8
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Polgar N, Fogelgren B. Regulation of Cell Polarity by Exocyst-Mediated Trafficking. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a031401. [PMID: 28264817 DOI: 10.1101/cshperspect.a031401] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
One requirement for establishing polarity within a cell is the asymmetric trafficking of intracellular vesicles to the plasma membrane. This tightly regulated process creates spatial and temporal differences in both plasma membrane composition and the membrane-associated proteome. Asymmetric membrane trafficking is also a critical mechanism to regulate cell differentiation, signaling, and physiology. Many eukaryotic cell types use the eight-protein exocyst complex to orchestrate polarized vesicle trafficking to certain membrane locales. Members of the exocyst were originally discovered in yeast while screening for proteins required for the delivery of secretory vesicles to the budding daughter cell. The same eight exocyst genes are conserved in mammals, in which the specifics of exocyst-mediated trafficking are highly cell-type-dependent. Some exocyst members bind to certain Rab GTPases on intracellular vesicles, whereas others localize to the plasma membrane at the site of exocytosis. Assembly of the exocyst holocomplex is responsible for tethering these vesicles to the plasma membrane before their soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated exocytosis. In this review, we will focus on the role and regulation of the exocyst complex in targeted vesicular trafficking as related to the establishment and maintenance of cellular polarity. We will contrast exocyst function in apicobasal epithelial polarity versus front-back mesenchymal polarity, and the dynamic regulation of exocyst-mediated trafficking during cell phenotype transitions.
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Affiliation(s)
- Noemi Polgar
- Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii 96813
| | - Ben Fogelgren
- Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii 96813
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9
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Noh MR, Jang HS, Song DK, Lee SR, Lipschutz JH, Park KM, Kim JI. Downregulation of exocyst Sec10 accelerates kidney tubule cell recovery through enhanced cell migration. Biochem Biophys Res Commun 2018; 496:309-315. [PMID: 29326040 DOI: 10.1016/j.bbrc.2018.01.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 01/03/2018] [Indexed: 12/23/2022]
Abstract
Migration of surviving kidney tubule cells after sub-lethal injury, for example ischemia/reperfusion (I/R), plays a critical role in recovery. Exocytosis is known to be involved in cell migration, and a key component in exocytosis is the highly-conserved eight-protein exocyst complex. We investigated the expression of a central exocyst complex member, Sec10, in kidneys following I/R injury, as well as the role of Sec10 in wound healing following scratch injury of cultured Madin-Darby canine kidney (MDCK) cells. Sec10 overexpression and knockdown (KD) in MDCK cells were used to investigate the speed of wound healing and the mechanisms underlying recovery. In mice, Sec10 decreased after I/R injury, and increased during the recovery period. In cell culture, Sec10 OE inhibited ruffle formation and wound healing, while Sec10 KD accelerated it. Sec10 OE cells had higher amounts of diacylglycerol kinase (DGK) gamma at the leading edge than did control cells. A DGK inhibitor reversed the inhibition of wound healing and ruffle formation in Sec10 OE cells. Conclusively, downregulation of Sec10 following I/R injury appears to accelerate recovery of kidney tubule cells through activated ruffle formation and enhanced cell migration.
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Affiliation(s)
- Mi Ra Noh
- Department of Anatomy and BK21 Plus, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Hee-Seong Jang
- Department of Anatomy and BK21 Plus, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Dae-Kyu Song
- Department of Physiology, Keimyung University School of Medicine, Daegu, Republic of Korea; Medical Research Center, Keimyung University School of Medicine, Daegu, Republic of Korea
| | - Seong-Ryong Lee
- Medical Research Center, Keimyung University School of Medicine, Daegu, Republic of Korea; Department of Pharmacology, Keimyung University School of Medicine, Daegu, Republic of Korea
| | - Joshua H Lipschutz
- Department of Medicine, Medical University of South Carolina and Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC, USA
| | - Kwon Moo Park
- Department of Anatomy and BK21 Plus, Kyungpook National University School of Medicine, Daegu, Republic of Korea.
| | - Jee In Kim
- Medical Research Center, Keimyung University School of Medicine, Daegu, Republic of Korea; Department of Molecular Medicine Keimyung University School of Medicine, Daegu, Republic of Korea.
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10
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Cook MS, Cazin C, Amoyel M, Yamamoto S, Bach E, Nystul T. Neutral Competition for Drosophila Follicle and Cyst Stem Cell Niches Requires Vesicle Trafficking Genes. Genetics 2017; 206:1417-1428. [PMID: 28512187 PMCID: PMC5500140 DOI: 10.1534/genetics.117.201202] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 05/10/2017] [Indexed: 12/03/2022] Open
Abstract
The process of selecting for cellular fitness through competition plays a critical role in both development and disease. The germarium, a structure at the tip of the ovariole of a Drosophila ovary, contains two follicle stem cells (FSCs) that undergo neutral competition for the stem cell niche. Using the FSCs as a model, we performed a genetic screen through a collection of 126 mutants in essential genes on the X chromosome to identify candidates that increase or decrease competition for the FSC niche. We identified ∼55 and 6% of the mutations screened as putative FSC hypo- or hyper-competitors, respectively. We found that a large majority of mutations in vesicle trafficking genes (11 out of the 13 in the collection of mutants) are candidate hypo-competition alleles, and we confirmed the hypo-competition phenotype for four of these alleles. We also show that Sec16 and another COPII vesicle trafficking component, Sar1, are required for follicle cell differentiation. Lastly, we demonstrate that, although some components of vesicle trafficking are also required for neutral competition in the cyst stem cells of the testis, there are important tissue-specific differences. Our results demonstrate a critical role for vesicle trafficking in stem cell niche competition and differentiation, and we identify a number of putative candidates for further exploration.
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Affiliation(s)
- Matthew S Cook
- Center for Reproductive Sciences, University of California, San Francisco, California 94143-0452
- Department of Anatomy, University of California, San Francisco, California 94143-0452
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California 94143-0452
| | - Coralie Cazin
- The Helen and Martin Kimmel Center for Stem Cell Biology, New York University School of Medicine, New York 10016
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York 10016
| | - Marc Amoyel
- The Helen and Martin Kimmel Center for Stem Cell Biology, New York University School of Medicine, New York 10016
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York 10016
- School of Cellular and Molecular Medicine, University of Bristol, BS8 1TD, United Kingdom
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Erika Bach
- The Helen and Martin Kimmel Center for Stem Cell Biology, New York University School of Medicine, New York 10016
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York 10016
| | - Todd Nystul
- Center for Reproductive Sciences, University of California, San Francisco, California 94143-0452
- Department of Anatomy, University of California, San Francisco, California 94143-0452
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California 94143-0452
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11
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Tanaka T, Goto K, Iino M. Diverse Functions and Signal Transduction of the Exocyst Complex in Tumor Cells. J Cell Physiol 2016; 232:939-957. [DOI: 10.1002/jcp.25619] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 09/23/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Toshiaki Tanaka
- Department of Anatomy and Cell Biology; School of Medicine; Yamagata University; Yamagata Japan
- Department of Dentistry, Oral and Maxillofacial Surgery; Plastic and Reconstructive Surgery; School of Medicine; Yamagata University; Yamagata Japan
| | - Kaoru Goto
- Department of Anatomy and Cell Biology; School of Medicine; Yamagata University; Yamagata Japan
| | - Mitsuyoshi Iino
- Department of Dentistry, Oral and Maxillofacial Surgery; Plastic and Reconstructive Surgery; School of Medicine; Yamagata University; Yamagata Japan
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12
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McKee RA, Wingert RA. Nephrotoxin Microinjection in Zebrafish to Model Acute Kidney Injury. J Vis Exp 2016. [PMID: 27500823 DOI: 10.3791/54241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid decline in renal function and development of the clinical syndrome known as acute kidney injury (AKI). Pharmacological agents used to treat medical circumstances ranging from bacterial infection to cancer, when administered individually or in combination with other drugs, can initiate AKI. Zebrafish are a useful animal model to study the chemical effects on renal function in vivo, as they form an embryonic kidney comprised of nephron functional units that are conserved with higher vertebrates, including humans. Further, zebrafish can be utilized to perform genetic and chemical screens, which provide opportunities to elucidate the cellular and molecular facets of AKI and develop therapeutic strategies such as the identification of nephroprotective molecules. Here, we demonstrate how microinjection into the zebrafish embryo can be utilized as a paradigm for nephrotoxin studies.
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Affiliation(s)
- Robert A McKee
- Center for Zebrafish Research, Department of Biological Sciences, University of Notre Dame; Center for Stem Cells and Regenerative Medicine, Department of Biological Sciences, University of Notre Dame
| | - Rebecca A Wingert
- Center for Zebrafish Research, Department of Biological Sciences, University of Notre Dame; Center for Stem Cells and Regenerative Medicine, Department of Biological Sciences, University of Notre Dame;
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13
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Martin-Urdiroz M, Deeks MJ, Horton CG, Dawe HR, Jourdain I. The Exocyst Complex in Health and Disease. Front Cell Dev Biol 2016; 4:24. [PMID: 27148529 PMCID: PMC4828438 DOI: 10.3389/fcell.2016.00024] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 03/11/2016] [Indexed: 01/23/2023] Open
Abstract
Exocytosis involves the fusion of intracellular secretory vesicles with the plasma membrane, thereby delivering integral membrane proteins to the cell surface and releasing material into the extracellular space. Importantly, exocytosis also provides a source of lipid moieties for membrane extension. The tethering of the secretory vesicle before docking and fusion with the plasma membrane is mediated by the exocyst complex, an evolutionary conserved octameric complex of proteins. Recent findings indicate that the exocyst complex also takes part in other intra-cellular processes besides secretion. These various functions seem to converge toward defining a direction of membrane growth in a range of systems from fungi to plants and from neurons to cilia. In this review we summarize the current knowledge of exocyst function in cell polarity, signaling and cell-cell communication and discuss implications for plant and animal health and disease.
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Affiliation(s)
| | - Michael J Deeks
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Connor G Horton
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Helen R Dawe
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Isabelle Jourdain
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
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14
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Drummond BE, Wingert RA. Insights into kidney stem cell development and regeneration using zebrafish. World J Stem Cells 2016; 8:22-31. [PMID: 26981168 PMCID: PMC4766248 DOI: 10.4252/wjsc.v8.i2.22] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Revised: 11/28/2015] [Accepted: 01/11/2016] [Indexed: 02/06/2023] Open
Abstract
Kidney disease is an escalating global health problem, for which the formulation of therapeutic approaches using stem cells has received increasing research attention. The complexity of kidney anatomy and function, which includes the diversity of renal cell types, poses formidable challenges in the identification of methods to generate replacement structures. Recent work using the zebrafish has revealed their high capacity to regenerate the integral working units of the kidney, known as nephrons, following acute injury. Here, we discuss these findings and explore the ways that zebrafish can be further utilized to gain a deeper molecular appreciation of renal stem cell biology, which may uncover important clues for regenerative medicine.
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15
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McKee RA, Wingert RA. Zebrafish Renal Pathology: Emerging Models of Acute Kidney Injury. CURRENT PATHOBIOLOGY REPORTS 2015; 3:171-181. [PMID: 25973344 PMCID: PMC4419198 DOI: 10.1007/s40139-015-0082-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The renal system is vital to maintain homeostasis in the body, where the kidneys contain nephron functional units that remove metabolic waste from the bloodstream, regulate fluids, and balance electrolytes. Severe organ damage from toxins or ischemia that occurs abruptly can cause acute kidney injury (AKI) in which there is a rapid, life-threatening loss of these activities. Humans have a limited but poorly understood ability to regenerate damaged nephrons after AKI. However, researchers studying AKI in vertebrate animal models such as mammals, and more recently the zebrafish, have documented robust regeneration within the nephron blood filter and tubule following injury. Further, zebrafish kidneys contain progenitors that create new nephrons after AKI. Here, we review investigations in zebrafish which have established a series of exciting renal pathology paradigms that complement existing AKI models and can be implemented to discover insights into kidney regeneration and the roles of stem cells.
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Affiliation(s)
- Robert A. McKee
- Department of Biological Sciences, Center for Zebrafish Research, Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Rebecca A. Wingert
- Department of Biological Sciences, Center for Zebrafish Research, Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN 46556 USA
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