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Perdaens O, Bottemanne P, van Pesch V. MicroRNAs dysregulated in multiple sclerosis affect the differentiation of CG-4 cells, an oligodendrocyte progenitor cell line. Front Cell Neurosci 2024; 18:1336439. [PMID: 38486710 PMCID: PMC10937391 DOI: 10.3389/fncel.2024.1336439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 01/24/2024] [Indexed: 03/17/2024] Open
Abstract
Introduction Demyelination is one of the hallmarks of multiple sclerosis (MS). While remyelination occurs during the disease, it is incomplete from the start and strongly decreases with its progression, mainly due to the harm to oligodendrocyte progenitor cells (OPCs), causing irreversible neurological deficits and contributing to neurodegeneration. Therapeutic strategies promoting remyelination are still very preliminary and lacking within the current treatment panel for MS. Methods In a previous study, we identified 21 microRNAs dysregulated mostly in the CSF of relapsing and/or remitting MS patients. In this study we transfected the mimics/inhibitors of several of these microRNAs separately in an OPC cell line, called CG-4. We aimed (1) to phenotypically characterize their effect on OPC differentiation and (2) to identify corroborating potential mRNA targets via immunocytochemistry, RT-qPCR analysis, RNA sequencing, and Gene Ontology enrichment analysis. Results We observed that the majority of 13 transfected microRNA mimics decreased the differentiation of CG-4 cells. We demonstrate, by RNA sequencing and independent RT-qPCR analyses, that miR-33-3p, miR-34c-5p, and miR-124-5p arrest OPC differentiation at a late progenitor stage and miR-145-5p at a premyelinating stage as evidenced by the downregulation of premyelinating oligodendrocyte (OL) [Tcf7l2, Cnp (except for miR-145-5p)] and mature OL (Plp1, Mbp, and Mobp) markers, whereas only miR-214-3p promotes OPC differentiation. We further propose a comprehensive exploration of their change in cell fate through Gene Ontology enrichment analysis. We finally confirm by RT-qPCR analyses the downregulation of several predicted mRNA targets for each microRNA that possibly support their effect on OPC differentiation by very distinctive mechanisms, of which some are still unexplored in OPC/OL physiology. Conclusion miR-33-3p, miR-34c-5p, and miR-124-5p arrest OPC differentiation at a late progenitor stage and miR-145-5p at a premyelinating stage, whereas miR-214-3p promotes the differentiation of CG-4 cells. We propose several potential mRNA targets and hypothetical mechanisms by which each microRNA exerts its effect. We hereby open new perspectives in the research on OPC differentiation and the pathophysiology of demyelination/remyelination, and possibly even in the search for new remyelinating therapeutic strategies in the scope of MS.
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Affiliation(s)
- Océane Perdaens
- Neurochemistry Group, Institute of NeuroScience, Université catholique de Louvain (UCLouvain), Brussels, Belgium
| | - Pauline Bottemanne
- Bioanalysis and Pharmacology of Bioactive Lipids, Louvain Drug Research Institute, Université catholique de Louvain (UCLouvain), Brussels, Belgium
| | - Vincent van Pesch
- Neurochemistry Group, Institute of NeuroScience, Université catholique de Louvain (UCLouvain), Brussels, Belgium
- Department of Neurology, Cliniques universitaires Saint-Luc, Université catholique de Louvain (UCLouvain), Brussels, Belgium
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2
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Doan RA, Monk KR. Dock1 acts cell-autonomously in Schwann cells to regulate the development, maintenance, and repair of peripheral myelin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.564271. [PMID: 37961336 PMCID: PMC10634861 DOI: 10.1101/2023.10.26.564271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Schwann cells, the myelinating glia of the peripheral nervous system (PNS), are critical for myelin development, maintenance, and repair. Rac1 is a known regulator of radial sorting, a key step in developmental myelination, and we previously showed in zebrafish that loss of Dock1, a Rac1-specific guanine nucleotide exchange factor, results in delayed peripheral myelination in development. We demonstrate here that Dock1 is necessary for myelin maintenance and remyelination after injury in adult zebrafish. Furthermore, it performs an evolutionary conserved role in mice, acting cell-autonomously in Schwann cells to regulate peripheral myelin development, maintenance, and repair. Additionally, manipulating Rac1 levels in larval zebrafish reveals that dock1 mutants are sensitized to inhibition of Rac1, suggesting an interaction between the two proteins during PNS development. We propose that the interplay between Dock1 and Rac1 signaling in Schwann cells is required to establish, maintain, and facilitate repair and remyelination within the peripheral nervous system.
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Affiliation(s)
- Ryan A Doan
- The Vollum Institute, Oregon Health & Science University, Portland, OR, USA
| | - Kelly R Monk
- The Vollum Institute, Oregon Health & Science University, Portland, OR, USA
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3
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Wen B, Li S, Ruan L, Yang Y, Chen Z, Zhang B, Yang X, Jie H, Li S, Zeng Z, Liu S. Engulfment and cell motility protein 1 fosters reprogramming of tumor-associated macrophages in colorectal cancer. Cancer Sci 2022; 114:410-422. [PMID: 36310143 PMCID: PMC9899619 DOI: 10.1111/cas.15628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 09/26/2022] [Accepted: 10/18/2022] [Indexed: 11/29/2022] Open
Abstract
Functional reprogramming of tumor-associated macrophages (TAMs) is crucial to their potent tumor-supportive capacity. However, the molecular mechanism behind the reprogramming process remains poorly understood. Here, we identify engulfment and cell motility protein 1 (ELMO1) as a crucial player for TAM reprogramming in colorectal cancer (CRC). The expression of ELMO1 in stromal but not epithelial tumor cells was positively associated with advanced clinical stage and poor disease-free survival in CRC. An increase in ELMO1 expression was specifically found in TAMs, but not in other multiple nonmalignant stromal cells. Gain- and loss-of-function assays indicated ELMO1 reprogrammed macrophages to a TAM-like phenotype through Rac1 activation. In turn, ELMO1-reprogrammed macrophages were shown to not only facilitate the malignant behaviors of CRC cells but exhibited potent phagocytosis of tumor cells. Taken together, our work underscores the importance of ELMO1 in determining functional reprogramming of TAMs and could provide new insights on potential therapeutic strategies against CRC.
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Affiliation(s)
- Bo Wen
- Department of Gastrointestinal SurgeryCentral Hospital of ShaoyangShaoyangChina
| | - Sheng Li
- Department of Gastrointestinal SurgeryCentral Hospital of ShaoyangShaoyangChina
| | - Lei Ruan
- Department of Colorectal Surgery and Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseasesThe Sixth Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina
| | - Yanping Yang
- Department of PathologyCentral Hospital of ShaoyangShaoyangChina
| | - Zilin Chen
- Department of Medical OncologyCentral Hospital of ShaoyangShaoyangChina
| | - Bin Zhang
- Department of Gastrointestinal SurgeryCentral Hospital of ShaoyangShaoyangChina
| | - Xin Yang
- Department of Colorectal Surgery and Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseasesThe Sixth Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina
| | - Haiqing Jie
- Department of Colorectal Surgery and Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseasesThe Sixth Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina
| | - Shujuan Li
- Department of PharmacyThe Third Affiliated Hospital of Zhengzhou UniversityZhengzhou, HenanChina
| | - Ziwei Zeng
- Department of Colorectal Surgery and Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor DiseasesThe Sixth Affiliated Hospital, Sun Yat‐sen UniversityGuangzhouChina,University Clinic MannheimMedical Faculty Mannheim, University of HeidelbergMannheimGermany
| | - Sisi Liu
- Department of PathologyCentral Hospital of ShaoyangShaoyangChina
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Mikdache A, Boueid MJ, Lesport E, Delespierre B, Loisel-Duwattez J, Degerny C, Tawk M. Timely Schwann cell division drives peripheral myelination in vivo via the laminin/cAMP pathway. Development 2022; 149:276236. [DOI: 10.1242/dev.200640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 07/29/2022] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Schwann cells (SCs) migrate along peripheral axons and divide intensively to generate the right number of cells prior to axonal ensheathment; however, little is known regarding the temporal and molecular control of their division and its impact on myelination. We report that Sil, a spindle pole protein associated with autosomal recessive primary microcephaly, is required for temporal mitotic exit of SCs. In sil-deficient cassiopeia (csp−/−) mutants, SCs fail to radially sort and myelinate peripheral axons. Elevation of cAMP, but not Rac1 activity, in csp−/− restores myelin ensheathment. Most importantly, we show a significant decrease in laminin expression within csp−/− posterior lateral line nerve and that forcing Laminin 2 expression in csp−/− fully restores the ability of SCs to myelinate. Thus, we demonstrate an essential role for timely SC division in mediating laminin expression to orchestrate radial sorting and peripheral myelination in vivo.
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Affiliation(s)
- Aya Mikdache
- U1195, Inserm, University Paris-Saclay , 94276 Le Kremlin Bicêtre , France
| | - Marie-José Boueid
- U1195, Inserm, University Paris-Saclay , 94276 Le Kremlin Bicêtre , France
| | - Emilie Lesport
- U1195, Inserm, University Paris-Saclay , 94276 Le Kremlin Bicêtre , France
| | | | | | - Cindy Degerny
- U1195, Inserm, University Paris-Saclay , 94276 Le Kremlin Bicêtre , France
| | - Marcel Tawk
- U1195, Inserm, University Paris-Saclay , 94276 Le Kremlin Bicêtre , France
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5
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Boger M, Bennewitz K, Wohlfart DP, Hausser I, Sticht C, Poschet G, Kroll J. Comparative Morphological, Metabolic and Transcriptome Analyses in elmo1−/−, elmo2−/−, and elmo3−/− Zebrafish Mutants Identified a Functional Non-Redundancy of the Elmo Proteins. Front Cell Dev Biol 2022; 10:918529. [PMID: 35874819 PMCID: PMC9304559 DOI: 10.3389/fcell.2022.918529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
The ELMO protein family consists of the homologues ELMO1, ELMO2 and ELMO3. Several studies have shown that the individual ELMO proteins are involved in a variety of cellular and developmental processes. However, it has poorly been understood whether the Elmo proteins show similar functions and act redundantly. To address this question, elmo1−/−, elmo2−/− and elmo3−/− zebrafish were generated and a comprehensive comparison of the phenotypic changes in organ morphology, transcriptome and metabolome was performed in these mutants. The results showed decreased fasting and increased postprandial blood glucose levels in adult elmo1−/−, as well as a decreased vascular formation in the adult retina in elmo1−/−, but an increased vascular formation in the adult elmo3−/− retina. The phenotypical comparison provided few similarities, as increased Bowman space areas in adult elmo1−/− and elmo2−/− kidneys, an increased hyaloid vessel diameter in elmo1−/− and elmo3−/− and a transcriptional downregulation of the vascular development in elmo1−/−, elmo2−/−, and elmo3−/− zebrafish larvae. Besides this, elmo1−/−, elmo2−/−, and elmo3−/− zebrafish exhibited several distinct changes in the vascular and glomerular structure and in the metabolome and the transcriptome. Especially, elmo3−/− zebrafish showed extensive differences in the larval transcriptome and an impaired survivability. Together, the data demonstrated that the three zebrafish Elmo proteins regulate not only similar but also divergent biological processes and mechanisms and show a low functional redundancy.
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Affiliation(s)
- Mike Boger
- Department of Vascular Biology and Tumor Angiogenesis, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Katrin Bennewitz
- Department of Vascular Biology and Tumor Angiogenesis, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - David Philipp Wohlfart
- Department of Vascular Biology and Tumor Angiogenesis, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Ingrid Hausser
- Institute of Pathology IPH, EM Lab, Heidelberg University Hospital, Heidelberg, Germany
| | - Carsten Sticht
- NGS Core Facility, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Gernot Poschet
- Metabolomics Core Technology Platform, Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
| | - Jens Kroll
- Department of Vascular Biology and Tumor Angiogenesis, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- *Correspondence: Jens Kroll,
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6
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Xue R, Wang Y, Wang T, Lyu M, Mo G, Fan X, Li J, Yen K, Yu S, Liu Q, Xu J. Functional Verification of Novel ELMO1 Variants by Live Imaging in Zebrafish. Front Cell Dev Biol 2021; 9:723804. [PMID: 34993193 PMCID: PMC8724260 DOI: 10.3389/fcell.2021.723804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 11/17/2021] [Indexed: 02/02/2023] Open
Abstract
ELMO1 (Engulfment and Cell Motility1) is a gene involved in regulating cell motility through the ELMO1-DOCK2-RAC complex. Contrary to DOCK2 (Dedicator of Cytokinesis 2) deficiency, which has been reported to be associated with immunodeficiency diseases, variants of ELMO1 have been associated with autoimmune diseases, such as diabetes and rheumatoid arthritis (RA). To explore the function of ELMO1 in immune cells and to verify the functions of novel ELMO1 variants in vivo, we established a zebrafish elmo1 mutant model. Live imaging revealed that, similar to mammals, the motility of neutrophils and T-cells was largely attenuated in zebrafish mutants. Consequently, the response of neutrophils to injury or bacterial infection was significantly reduced in the mutants. Furthermore, the reduced mobility of neutrophils could be rescued by the expression of constitutively activated Rac proteins, suggesting that zebrafish elmo1 mutant functions via a conserved mechanism. With this mutant, three novel human ELMO1 variants were transiently and specifically expressed in zebrafish neutrophils. Two variants, p.E90K (c.268G>A) and p.D194G (c.581A>G), could efficiently recover the motility defect of neutrophils in the elmo1 mutant; however, the p.R354X (c.1060C>T) variant failed to rescue the mutant. Based on those results, we identified that zebrafish elmo1 plays conserved roles in cell motility, similar to higher vertebrates. Using the transient-expression assay, zebrafish elmo1 mutants could serve as an effective model for human variant verification in vivo.
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Affiliation(s)
- Rongtao Xue
- Department of Hematology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Ying Wang
- Department of Developmental Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | | | - Mei Lyu
- Laboratory of Immunology and Regeneration, School of Medicine, South China University of Technology, Guangzhou, China
| | - Guiling Mo
- GuangZhou KingMed Center For Clinical Laboratory Co., Ltd., International Biotech Island, Guangzhou, China
| | - Xijie Fan
- GuangZhou KingMed Center For Clinical Laboratory Co., Ltd., International Biotech Island, Guangzhou, China
| | - Jianchao Li
- Laboratory of Molecular and Structural Biology, School of Medicine, South China University of Technology, Guangzhou, China
| | - Kuangyu Yen
- Department of Developmental Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- *Correspondence: Kuangyu Yen, ; Shihui Yu, ; Qifa Liu, ; Jin Xu,
| | - Shihui Yu
- GuangZhou KingMed Center For Clinical Laboratory Co., Ltd., International Biotech Island, Guangzhou, China
- *Correspondence: Kuangyu Yen, ; Shihui Yu, ; Qifa Liu, ; Jin Xu,
| | - Qifa Liu
- Department of Hematology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- *Correspondence: Kuangyu Yen, ; Shihui Yu, ; Qifa Liu, ; Jin Xu,
| | - Jin Xu
- Laboratory of Immunology and Regeneration, School of Medicine, South China University of Technology, Guangzhou, China
- *Correspondence: Kuangyu Yen, ; Shihui Yu, ; Qifa Liu, ; Jin Xu,
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7
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TNF-α-mediated m 6A modification of ELMO1 triggers directional migration of mesenchymal stem cell in ankylosing spondylitis. Nat Commun 2021; 12:5373. [PMID: 34508078 PMCID: PMC8433149 DOI: 10.1038/s41467-021-25710-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 08/12/2021] [Indexed: 12/12/2022] Open
Abstract
Ankylosing spondylitis (AS) is a type of rheumatic disease characterized by chronic inflammation and pathological osteogenesis in the entheses. Previously, we demonstrated that enhanced osteogenic differentiation of MSC from AS patients (AS-MSC) resulted in pathological osteogenesis, and that during the enhanced osteogenic differentiation course, AS-MSC induced TNF-α-mediated local inflammation. However, whether TNF-α in turn affects AS-MSC remains unknown. Herein, we further demonstrate that a high-concentration TNF-α treatment triggers enhanced directional migration of AS-MSC in vitro and in vivo, which enforces AS pathogenesis. Mechanistically, TNF-α leads to increased expression of ELMO1 in AS-MSC, which is mediated by a METTL14 dependent m6A modification in ELMO1 3′UTR. Higher ELMO1 expression of AS-MSC is found in vivo in AS patients, and inhibiting ELMO1 in SKG mice produces therapeutic effects in this spondyloarthritis model. This study may provide insight into not only the pathogenesis but also clinical therapy for AS. Abnormal functions of mesenchymal stem cells (MSC) contribute into the pathogenensis of ankylosing spondylitis (AS). Here, the authors show that TNF-α at high concentration induces enhances migration of AS-MSC through METTL14 mediated m6A modification of the ELMO1 3′ UTR.
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Rgs4 is a regulator of mTOR activity required for motoneuron axon outgrowth and neuronal development in zebrafish. Sci Rep 2021; 11:13338. [PMID: 34172795 PMCID: PMC8233358 DOI: 10.1038/s41598-021-92758-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 06/15/2021] [Indexed: 12/21/2022] Open
Abstract
The Regulator of G protein signaling 4 (Rgs4) is a member of the RGS proteins superfamily that modulates the activity of G-protein coupled receptors. It is mainly expressed in the nervous system and is linked to several neuronal signaling pathways; however, its role in neural development in vivo remains inconclusive. Here, we generated and characterized a rgs4 loss of function model (MZrgs4) in zebrafish. MZrgs4 embryos showed motility defects and presented reduced head and eye sizes, reflecting defective motoneurons axon outgrowth and a significant decrease in the number of neurons in the central and peripheral nervous system. Forcing the expression of Rgs4 specifically within motoneurons rescued their early defective outgrowth in MZrgs4 embryos, indicating an autonomous role for Rgs4 in motoneurons. We also analyzed the role of Akt, Erk and mechanistic target of rapamycin (mTOR) signaling cascades and showed a requirement for these pathways in motoneurons axon outgrowth and neuronal development. Drawing on pharmacological and rescue experiments in MZrgs4, we provide evidence that Rgs4 facilitates signaling mediated by Akt, Erk and mTOR in order to drive axon outgrowth in motoneurons and regulate neuronal numbers.
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9
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Benson CE, Southgate L. The DOCK protein family in vascular development and disease. Angiogenesis 2021; 24:417-433. [PMID: 33548004 PMCID: PMC8292242 DOI: 10.1007/s10456-021-09768-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 01/06/2021] [Accepted: 01/16/2021] [Indexed: 02/07/2023]
Abstract
The vascular network is established and maintained through the processes of vasculogenesis and angiogenesis, which are tightly regulated during embryonic and postnatal life. The formation of a functional vasculature requires critical cellular mechanisms, such as cell migration, proliferation and adhesion, which are dependent on the activity of small Rho GTPases, controlled in part by the dedicator of cytokinesis (DOCK) protein family. Whilst the majority of DOCK proteins are associated with neuronal development, a growing body of evidence has indicated that members of the DOCK family may have key functions in the control of vasculogenic and angiogenic processes. This is supported by the involvement of several angiogenic signalling pathways, including chemokine receptor type 4 (CXCR4), vascular endothelial growth factor (VEGF) and phosphatidylinositol 3-kinase (PI3K), in the regulation of specific DOCK proteins. This review summarises recent progress in understanding the respective roles of DOCK family proteins during vascular development. We focus on existing in vivo and in vitro models and known human disease phenotypes and highlight potential mechanisms of DOCK protein dysfunction in the pathogenesis of vascular disease.
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Affiliation(s)
- Clare E Benson
- Genetics Research Centre, Molecular and Clinical Sciences Research Institute, St. George's University of London, Cranmer Terrace, London, SW17 0RE, UK
| | - Laura Southgate
- Genetics Research Centre, Molecular and Clinical Sciences Research Institute, St. George's University of London, Cranmer Terrace, London, SW17 0RE, UK. .,Department of Medical & Molecular Genetics, Faculty of Life Sciences & Medicine, King's College London, London, SE1 9RT, UK.
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Rho GTPases Signaling in Zebrafish Development and Disease. Cells 2020; 9:cells9122634. [PMID: 33302361 PMCID: PMC7762611 DOI: 10.3390/cells9122634] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/30/2020] [Accepted: 12/07/2020] [Indexed: 02/08/2023] Open
Abstract
Cells encounter countless external cues and the specificity of their responses is translated through a myriad of tightly regulated intracellular signals. For this, Rho GTPases play a central role and transduce signals that contribute to fundamental cell dynamic and survival events. Here, we review our knowledge on how zebrafish helped us understand the role of some of these proteins in a multitude of in vivo cellular behaviors. Zebrafish studies offer a unique opportunity to explore the role and more specifically the spatial and temporal dynamic of Rho GTPases activities within a complex environment at a level of details unachievable in any other vertebrate organism.
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Chan WWR, Li W, Chang RCC, Lau KF. ARF6-Rac1 signaling-mediated neurite outgrowth is potentiated by the neuronal adaptor FE65 through orchestrating ARF6 and ELMO1. FASEB J 2020; 34:16397-16413. [PMID: 33047393 DOI: 10.1096/fj.202001703r] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/13/2020] [Accepted: 10/02/2020] [Indexed: 12/24/2022]
Abstract
Ras-related C3 botulinum toxin substrate 1 (Rac1) is a member of the Rho family of GTPases that functions as a molecular switch to regulate many important cellular events including actin cytoskeleton remodeling during neurite outgrowth. Engulfment and cell motility 1 (ELMO1)-dedicator of cytokinesis 1 (DOCK180) is a bipartite guanine nucleotide exchange factor (GEF) complex that has been reported to activate Rac1 on the plasma membrane (PM). Emerging evidence suggests that the small GTPase ADP ribosylation factor 6 (ARF6) activates Rac1 via the ELMO1/DOCK180 complex. However, the exact mechanism by which ARF6 triggers ELMO1/DOCK180-mediated Rac1 signaling remains unclear. Here, we report that the neuronal scaffold protein FE65 serves as a functional link between ARF6 and ELMO1, allowing the formation of a multimeric signaling complex. Interfering with formation of this complex by transfecting either FE65-binding-defective mutants or FE65 siRNA attenuates both ARF6-ELMO1-mediated Rac1 activation and neurite elongation. Notably, the PM trafficking of ELMO1 is markedly decreased in cells with suppressed expression of either FE65 or ARF6. Likewise, this process is attenuated in the FE65-binding-defective mutants transfected cells. Moreover, overexpression of FE65 increases the amount of ELMO1 in the recycling endosome, an organelle responsible for returning proteins to the PM, whereas knockout of FE65 shows opposite effect. Together, our data indicates that FE65 potentiates ARF6-Rac1 signaling by orchestrating ARF6 and ELMO1 to promote the PM trafficking of ELMO1 via the endosomal recycling pathway, and thus, promotes Rac1-mediated neurite outgrowth.
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Affiliation(s)
- Wai Wa Ray Chan
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Wen Li
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China.,Research Laboratory for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Raymond Chuen Chung Chang
- Laboratory of Neurodegenerative Diseases, School of Biomedical Sciences, LKS Faculty of Medicine, and State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Kwok-Fai Lau
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
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