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Cáceres P, Barría A, Christensen KA, Bassini LN, Correa K, Garcia B, Lhorente JP, Yáñez JM. Genome-scale comparative analysis for host resistance against sea lice between Atlantic salmon and rainbow trout. Sci Rep 2021; 11:13231. [PMID: 34168167 PMCID: PMC8225872 DOI: 10.1038/s41598-021-92425-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 06/10/2021] [Indexed: 11/08/2022] Open
Abstract
Sea lice (Caligus rogercresseyi) is an ectoparasite which causes major production losses in the salmon aquaculture industry worldwide. Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) are two of the most susceptible salmonid species to sea lice infestation. The objectives of this study were to: (1) identify genomic regions associated with resistance to Caligus rogercresseyi in Atlantic salmon and rainbow trout by performing single-step Genome-Wide Association studies (ssGWAS), and (2) identify candidate genes related to trait variation based on exploring orthologous genes within the associated regions across species. A total of 2626 Atlantic salmon and 2643 rainbow trout were challenged and genotyped with 50 K and 57 K SNP panels, respectively. We ran two independent ssGWAS for sea lice resistance on each species and identified 7 and 13 regions explaining more than 1% of the genetic variance for the trait, with the most important regions explaining 3% and 2.7% for Atlantic salmon and rainbow trout, respectively. We identified genes associated with immune response, cytoskeleton function, and cell migration when focusing on important genomic regions for each species. Moreover, we found 15 common orthogroups which were present in more than one associated genomic region, within- or between-species; however, only one orthogroup showed a clear potential biological relevance in the response against sea lice. For instance, dual-specificity protein phosphatase 10-like (dusp10) and dual-specificity protein phosphatase 8 (dusp8) were found in genomic regions associated with lice density in Atlantic salmon and rainbow trout, respectively. Dusp10 and dusp8 are modulators of the MAPK pathway and might be involved in the differences of the inflammation response between lice resistant and susceptible fish from both species. Our results provide further knowledge on candidate genes related to sea lice resistance and may help establish better control for sea lice in fish populations.
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Affiliation(s)
- Pablo Cáceres
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Av. Santa Rosa 11735, La Pintana, 8820808, Santiago, Chile
| | - Agustín Barría
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh Easter Bush, Midlothian, EH25 9RG, UK
| | - Kris A Christensen
- Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC, Canada
| | - Liane N Bassini
- Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Katharina Correa
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Av. Santa Rosa 11735, La Pintana, 8820808, Santiago, Chile
| | - Baltasar Garcia
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Av. Santa Rosa 11735, La Pintana, 8820808, Santiago, Chile
- School of Agricultural and Veterinary Sciences, UNESP-Sao Paulo State University, Jaboticabal, 14884900, Brazil
| | | | - José M Yáñez
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Av. Santa Rosa 11735, La Pintana, 8820808, Santiago, Chile.
- Núcleo Milenio INVASAL, Concepción, Chile.
- Center for Research and Innovation in Aquaculture (CRIA), Universidad de Chile, Santiago, Santiago, Chile.
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Wang M, Hu Y, Li M, Xu Q, Zhang X, Wang X, Xue X, Xiao Q, Liu J, Wang H. A proteomics analysis of the ovarian development in females of Haemaphysalis longicornis. EXPERIMENTAL & APPLIED ACAROLOGY 2020; 80:289-309. [PMID: 31919614 DOI: 10.1007/s10493-020-00469-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 01/03/2020] [Indexed: 06/10/2023]
Abstract
Haemaphysalis longicornis is an ixodid tick that can spread a wide variety of pathogens, affecting humans, livestock and wildlife health. The high reproductive capability of this species is initiated by the ingestion of a large amount of blood ingested by the engorged female tick. The degree of ovarian development is proportional to the number of eggs laid. Studying the regulatory mechanism of tick ovary development is relevant for the development of novel tick control methods. In this study, we used quantitative proteomics to study the dynamic changes in protein expression and protein phosphorylation during ovarian development of engorged female H. longicornis ticks. Synergistic action of many proteins (n = 3031) is required to achieve ovarian development and oocyte formation rapidly. Through bioinformatics analysis, changes in protein expressions and phosphorylation modifications in regulating the ovarian development of female ticks are described. Many proteins play an essential role during ovarian development. Also, protein phosphorylation appeared an important reproductive strategy to enable ticks to efficiently convert large amounts of blood in the ovaries into egg-producing components and ultimately produce many eggs.
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Affiliation(s)
- Minjing Wang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Yuhong Hu
- Instrumental Analysis Center, Hebei Normal University, Shijiazhuang, 050024, China
| | - Mengxue Li
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Qianqian Xu
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Xiaoli Zhang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Xiaoshuang Wang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Xiaomin Xue
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Qi Xiao
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China
| | - Jingze Liu
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
- , Shijiazhuang, Hebei, China.
| | - Hui Wang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, 050024, China.
- , Shijiazhuang, Hebei, China.
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Pan C, Zhang Y, Meng Q, Dai G, Jiang Z, Bao H. Down Regulation of the Expression of ELMO3 by COX2 Inhibitor Suppresses Tumor Growth and Metastasis in Non-Small-Cell Lung Cancer. Front Oncol 2019; 9:363. [PMID: 31134158 PMCID: PMC6515945 DOI: 10.3389/fonc.2019.00363] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 04/18/2019] [Indexed: 01/04/2023] Open
Abstract
Non-small cell lung cancer (NSCLC) is one of the most common malignancies. Studies have shown that engulfment and cell motility 3 (ELMO3) is highly expressed in NSCLC and can be used as a novel biomarker, but its underlying mechanism remains to be explored. The aim of this study was to investigate the mechanism by which ELMO3 may be down-regulated by COX-2 inhibitors to inhibit NSCLC. NSCLC tissue and adjacent normal lung tissue from 24 patients were used to detect the mRNA and protein expression of ELMO3, COX-2, and other related proteins by Western blot, RT-PCR, and Immunohistochemical analysis. Lewis Lung carcinoma (LLC) cells were used to investigate the effects and the mechanism of siELMO3 and COX-2 inhibitor. C57BL/6 mice inoculated with LLC cells by subcutaneous (s.c.) injection were used to detect the in vivo effects of cox-2 inhibitor. The expression of ELMO3 and cyclooxygenase-2 (COX-2) in human NSCLC tissues was significantly increased compared with that in the adjacent normal tissues. ELMO3 exhibited a positive correlation with COX-2 expression. Moreover, knockdown of ELMO3 suppressed the epithelial-mesenchymal transition (EMT), adhesion, and metastasis of Lewis lung carcinoma (LLC) cells. Importantly, Parecoxib, a selective inhibitor of COX-2, significantly reduced the expression of ELMO3 and EMT in LLC cells and LLC-bearing mice. Furthermore, it could inhibit the growth, adhesion and metastasis of LLC cells in vitro. Our results demonstrate that down regulation of ELMO3 suppressed growth and metastasis of lung cancer by inhibiting EMT. Parecoxib could reduce ELMO3 expression and suppress growth and metastasis of lung cancer, which might be a useful chemotherapeutic agent for inhibiting metastasis and recurrence of NSCLC.
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Affiliation(s)
- Cailong Pan
- Department of Anesthesiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Yong Zhang
- Department of Anesthesiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Qinghai Meng
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, China
| | - Guoliang Dai
- Department of Clinical Pharmacology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
| | - Zhitao Jiang
- Department of Pharmacy Office, Zhangjiagang Hospital of Traditional Chinese Medicine Affiliated to Nanjing University of Chinese Medicine, Zhangjiagang, China
| | - Hongguang Bao
- Department of Anesthesiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
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Silencing ELMO3 Inhibits the Growth, Invasion, and Metastasis of Gastric Cancer. BIOMED RESEARCH INTERNATIONAL 2018; 2018:3764032. [PMID: 30345300 PMCID: PMC6174816 DOI: 10.1155/2018/3764032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 09/03/2018] [Indexed: 12/19/2022]
Abstract
ELMO3 is a member of the engulfment and cell motility (ELMO) protein family, which plays a vital role in the process of chemotaxis and metastasis of tumor cells. However, remarkably little is known about the role of ELMO3 in cancer. The present study was conducted to investigate the function and role of ELMO3 in gastric cancer (GC) progression. The expression level of ELMO3 in gastric cancer tissues and cell lines was measured by means of real-time quantitative PCR (qPCR) and Western blot analysis. RNA interference was used to inhibit ELMO3 expression in gastric cancer cells. Then, wound-healing assays, Transwell assays, MTS assays, flow cytometry, and fluorescence microscopy were applied to detect cancer cell migration, cell invasion, cell proliferation, the cell cycle, and F-actin polymerization, respectively. The results revealed that ELMO3 expression in GC tumor tissues was significantly higher than in the paired adjacent tissues. Moreover, knockdown of ELMO3 by a specific siRNA significantly inhibited the processes of cell proliferation, invasion, metastasis, regulation of the cell cycle, and F-actin polymerization. Collectively, the results indicate that ELMO3 participates in the processes of cell growth, invasion, and migration, and ELMO3 is expected to be a potential diagnostic and prognostic marker for GC.
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Xu X, Jin T. ELMO proteins transduce G protein-coupled receptor signal to control reorganization of actin cytoskeleton in chemotaxis of eukaryotic cells. Small GTPases 2017. [PMID: 28641070 PMCID: PMC6548286 DOI: 10.1080/21541248.2017.1318816] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Chemotaxis, which is chemoattractant-guided directional cell migration, plays major roles in recruitment of neutrophils, the metastasis of cancer cells, and the development of the model organism Dictyostelium discoideum. These cells share remarkable similarities in the signaling pathways by which they control chemotaxis. They all use a G protein-coupled receptor (GPCR)-mediated signal transduction pathway to sense the chemotactic gradient to guide cell migration. Diverse chemokines activate Rac through conserved GPCR signaling pathways. ELMO proteins are an evolutionarily conserved, essential component of the ELMO/Dock complex, which functions as a guanine nucleotide exchange factor (GEF) for small G protein Rac activation. The linkages between the GPCR-initiated gradient sensing compass and the Rac-mediated migrating machinery have long been missing. Here, we summarize recent findings on ELMO proteins that directly interact with G protein and transduce GPCR signaling to control the reorganization of actin-based cytoskeleton through regulating Rac activation during chemotaxis, first in D. discoideum and then in mammalian cancer cells. This represents an evolutionarily conserved signaling shortcut from GPCR to the actin cytoskeleton.
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Affiliation(s)
- Xuehua Xu
- a Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases , National Institutes of Health , Rockville , MD , USA
| | - Tian Jin
- a Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases , National Institutes of Health , Rockville , MD , USA
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Knockdown of ELMO3 Suppresses Growth, Invasion and Metastasis of Colorectal Cancer. Int J Mol Sci 2016; 17:ijms17122119. [PMID: 27999268 PMCID: PMC5187919 DOI: 10.3390/ijms17122119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 12/05/2016] [Accepted: 12/12/2016] [Indexed: 01/08/2023] Open
Abstract
The engulfment and cell motility (ELMOs) family of proteins plays a crucial role in tumor cell migration and invasion. However, the function of ELMO3 is poorly defined. To elucidate its role in the development and progression of colorectal cancer (CRC), we examined the expression of ELMO3 in 45 cases of paired CRC tumor tissues and adjacent normal tissues. Furthermore, we assessed the effect of the knockdown of ELMO3 on cell proliferation, cell cycle, migration, invasion and F-actin polymerization in HCT116 cells. The result shows that the expression of ELMO3 in CRC tissues was significantly increased in comparison to the adjacent normal colorectal tissues. Moreover, this overexpression was associated with tumor size (p = 0.007), tumor differentiation (p = 0.001), depth of invasion (p = 0.009), lymph node metastasis (p = 0.003), distant metastasis (p = 0.013) and tumor, node, metastasis (TNM)-based classification (p = 0.000). In in vitro experiments, the silencing of ELMO3 inhibited cell proliferation, invasion, metastasis, and F-actin polymerization, and induced Gap 1 (G1) phase cell cycle arrest. Our study demonstrates that ELMO3 is involved in the processes of growth, invasion and metastasis of CRC, and could be used a potential molecular diagnostic tool or therapy target of CRC.
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Hoefle C, Hückelhoven R. A barley Engulfment and Motility domain containing protein modulates Rho GTPase activating protein HvMAGAP1 function in the barley powdery mildew interaction. PLANT MOLECULAR BIOLOGY 2014; 84:469-478. [PMID: 24142383 DOI: 10.1007/s11103-013-0145-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 10/11/2013] [Indexed: 06/02/2023]
Abstract
Engulfment and Motility (ELMO) proteins are involved in the regulation of small GTPase activity in eukaryotic organisms, but little is known about ELMO proteins in plants. We isolated the barley ELMO Domain Containing Protein, HvELMOD_C, in a yeast two hybrid screen for proteins interacting with HvMAGAP1 (Microtubule Associated ROP-GTPase Activating Protein 1). HvMAGAP1 is considered as an antagonist of barley RACB, a member of the RHO of plant (ROP) family GTPases, which functions as a susceptibility factor in the interaction of barley with the barley powdery mildew fungus Blumeria graminis f.sp. hordei. HvELMOD_C interacts with the central RHO-GAP domain of HvMAGAP1. Cytoplasmic HvELMOD_C translocates to microtubules on co-expression of HvMAGAP1 but not on co-expression of HvMAGAP1-R185G, a mutant of the catalytically active arginine R185 in the RHO-GAP domain. HvELMOD_C, when simultaneously expressed with HvMAGAP1, abolished the resistance-inducing effect of HvMAGAP1 to B. graminis f.sp. hordei. Therefore, HvELMOD_C might function as a new modulator of HvMAGAP1 and thus ROP activity in barley.
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Affiliation(s)
- Caroline Hoefle
- Lehrstuhl für Phytopathologie, Technische Universität München, Emil-Ramann-Straße 2, 85350, Freising-Weihenstephan, Germany
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Schoen CJ, Burmeister M, Lesperance MM. Diaphanous homolog 3 (Diap3) overexpression causes progressive hearing loss and inner hair cell defects in a transgenic mouse model of human deafness. PLoS One 2013; 8:e56520. [PMID: 23441200 PMCID: PMC3575478 DOI: 10.1371/journal.pone.0056520] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 01/12/2013] [Indexed: 12/27/2022] Open
Abstract
We previously demonstrated that a mutation in the 5′ untranslated region of Diaphanous homolog 3 (DIAPH3) results in 2 to 3-fold overexpression of the gene, leading to a form of delayed onset, progressive human deafness known as AUNA1 (auditory neuropathy, nonsyndromic, autosomal dominant, 1). To investigate the mechanism of deafness, we generated two lines of transgenic mice overexpressing Diap3, the murine ortholog of DIAPH3, on an FVB/NJ background. Line 771 exhibits a relatively mild 20 dB hearing loss at 12 kHz at 4 and 8 weeks of age, progressing to 40 dB and 60 dB losses at 16 and 24 weeks, respectively, at 12 and 24 kHz. Line 924 shows no hearing loss at 4 or 8 weeks, but manifests 35 and 50 dB threshold shifts at 16 and 24 weeks, respectively, at both 12 and 24 kHz. Notably, mice from the two transgenic lines retain distortion product otoacoustic emissions, indicative of normal cochlear outer hair cell (OHC) function despite elevation of auditory thresholds. Scanning electron microscopy of the organ of Corti demonstrates striking anomalies of the inner hair cell (IHC) stereocilia, while OHCs are essentially intact. Over time, IHCs of both lines develop elongated stereocilia that appear fused with neighboring stereocilia, in parallel to the time course of hearing loss in each line. Furthermore, we observe significant reduction in the number of IHC ribbon synapses over 24 weeks in both lines, although this reduction does not correlate temporally with onset and progression of hearing loss or stereociliary anomalies. In summary, overexpression of wild-type Diap3 in two lines of transgenic mice results in hearing loss that recapitulates human AUNA1 deafness. These findings suggest an essential role of Diap3 in regulating assembly and/or maintenance of actin filaments in IHC stereocilia, as well as a potential role at the IHC ribbon synapse.
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MESH Headings
- Animals
- Auditory Threshold
- Deafness/genetics
- Disease Models, Animal
- Female
- Gene Expression
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/pathology
- Hair Cells, Auditory, Inner/ultrastructure
- Hair Cells, Auditory, Outer/metabolism
- Humans
- Mice
- Mice, Transgenic
- Microtubule-Associated Proteins/genetics
- NADPH Dehydrogenase/genetics
- Stereocilia/pathology
- Stereocilia/ultrastructure
- Transgenes
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Affiliation(s)
- Cynthia J. Schoen
- Neuroscience Program, University of Michigan Health System, Ann Arbor, Michigan, United States of America
- Molecular and Behavioral Neuroscience Institute, University of Michigan Health System, Ann Arbor, Michigan, United States of America
| | - Margit Burmeister
- Molecular and Behavioral Neuroscience Institute, University of Michigan Health System, Ann Arbor, Michigan, United States of America
- Department of Human Genetics, University of Michigan Health System, Ann Arbor, Michigan, United States of America
- Department of Psychiatry, University of Michigan Health System, Ann Arbor, Michigan, United States of America
| | - Marci M. Lesperance
- Division of Pediatric Otolaryngology, Department of Otolaryngology-Head and Neck Surgery, University of Michigan Health System, Ann Arbor, Michigan, United States of America
- * E-mail:
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East MP, Bowzard JB, Dacks JB, Kahn RA. ELMO domains, evolutionary and functional characterization of a novel GTPase-activating protein (GAP) domain for Arf protein family GTPases. J Biol Chem 2012; 287:39538-53. [PMID: 23014990 DOI: 10.1074/jbc.m112.417477] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human family of ELMO domain-containing proteins (ELMODs) consists of six members and is defined by the presence of the ELMO domain. Within this family are two subclassifications of proteins, based on primary sequence conservation, protein size, and domain architecture, deemed ELMOD and ELMO. In this study, we used homology searching and phylogenetics to identify ELMOD family homologs in genomes from across eukaryotic diversity. This demonstrated not only that the protein family is ancient but also that ELMOs are potentially restricted to the supergroup Opisthokonta (Metazoa and Fungi), whereas proteins with the ELMOD organization are found in diverse eukaryotes and thus were likely the form present in the last eukaryotic common ancestor. The segregation of the ELMO clade from the larger ELMOD group is consistent with their contrasting functions as unconventional Rac1 guanine nucleotide exchange factors and the Arf family GTPase-activating proteins, respectively. We used unbiased, phylogenetic sorting and sequence alignments to identify the most highly conserved residues within the ELMO domain to identify a putative GAP domain within the ELMODs. Three independent but complementary assays were used to provide an initial characterization of this domain. We identified a highly conserved arginine residue critical for both the biochemical and cellular GAP activity of ELMODs. We also provide initial evidence of the function of human ELMOD1 as an Arf family GAP at the Golgi. These findings provide the basis for the future study of the ELMOD family of proteins and a new avenue for the study of Arf family GTPases.
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Affiliation(s)
- Michael P East
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Xu X, Jin T. A shortcut from GPCR signaling to Rac-mediated actin cytoskeleton through an ELMO/DOCK complex. Small GTPases 2012; 3:183-5. [PMID: 22647486 PMCID: PMC3442806 DOI: 10.4161/sgtp.20271] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Chemotaxis, chemoattractant-guided directional cell migration, plays major roles in human innate immunity and in development of a model organism Dictyostelium discoideum. Human leukocytes and D. disscoideum share remarkable similarities in the molecular mechanisms that control chemotaxis. These cells use G-Protein-Coupled Receptors (GPCRs), such as chemokine receptors, to control a signaling network that carries out chemotactic gradient sensing and directs cell migration. Diverse chemokines bind to their receptors to activate small G protein Rac through an evolutionarily conserved mechanism. Elmo and Dock180 proteins form ELMO/Dock180 complexes functioning as guanine nucleotide exchange factors (GEFs) for Rac activation. However, the linkage between GPCR to Elmo/Dock180 for Rac activation that controls F-actin dynamics remained unclear. Recently, we discovered a novel function of an ELMO protein in Dictyostelium discoideum linking GPCR signaling from Gβ to actin dynamics through regulating Rac activation during chemotaxis.
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Affiliation(s)
- Xuehua Xu
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.
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Johnson KR, Longo-Guess CM, Gagnon LH. Mutations of the mouse ELMO domain containing 1 gene (Elmod1) link small GTPase signaling to actin cytoskeleton dynamics in hair cell stereocilia. PLoS One 2012; 7:e36074. [PMID: 22558334 PMCID: PMC3338648 DOI: 10.1371/journal.pone.0036074] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 03/25/2012] [Indexed: 11/18/2022] Open
Abstract
Stereocilia, the modified microvilli projecting from the apical surfaces of the sensory hair cells of the inner ear, are essential to the mechanoelectrical transduction process underlying hearing and balance. The actin-filled stereocilia on each hair cell are tethered together by fibrous links to form a highly patterned hair bundle. Although many structural components of hair bundles have been identified, little is known about the signaling mechanisms that regulate their development, morphology, and maintenance. Here, we describe two naturally occurring, allelic mutations that result in hearing and balance deficits in mice, named roundabout (rda) and roundabout-2J (rda(2J)). Positional cloning identified both as mutations of the mouse ELMO domain containing 1 gene (Elmod1), a poorly characterized gene with no previously reported mutant phenotypes. The rda mutation is a 138 kb deletion that includes exons 1-5 of Elmod1, and rda(2J) is an intragenic duplication of exons 3-8 of Elmod1. The deafness associated with these mutations is caused by cochlear hair cell dysfunction, as indicated by conspicuous elongations and fusions of inner hair cell stereocilia and progressive degeneration of outer hair cell stereocilia. Mammalian ELMO-family proteins are known to be involved in complexes that activate small GTPases to regulate the actin cytoskeleton during phagocytosis and cell migration. ELMOD1 and ELMOD2 recently were shown to function as GTPase-activating proteins (GAPs) for the Arf family of small G proteins. Our finding connecting ELMOD1 deficiencies with stereocilia dysmorphologies thus establishes a link between the Ras superfamily of small regulatory GTPases and the actin cytoskeleton dynamics of hair cell stereocilia.
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12
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A Gβγ effector, ElmoE, transduces GPCR signaling to the actin network during chemotaxis. Dev Cell 2012; 22:92-103. [PMID: 22264729 DOI: 10.1016/j.devcel.2011.11.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 10/19/2011] [Accepted: 11/15/2011] [Indexed: 10/14/2022]
Abstract
Activation of G protein-coupled receptors (GPCRs) leads to the dissociation of heterotrimeric G-proteins into Gα and Gβγ subunits, which go on to regulate various effectors involved in a panoply of cellular responses. During chemotaxis, Gβγ subunits regulate actin assembly and migration, but the protein(s) linking Gβγ to the actin cytoskeleton remains unknown. Here, we identified a Gβγ effector, ElmoE in Dictyostelium, and demonstrated that it is required for GPCR-mediated chemotaxis. Remarkably, ElmoE associates with Gβγ and Dock-like proteins to activate the small GTPase Rac, in a GPCR-dependent manner, and also associates with Arp2/3 complex and F-actin. Thus, ElmoE serves as a link between chemoattractant GPCRs, G-proteins and the actin cytoskeleton. The pathway, consisting of GPCR, Gβγ, Elmo/Dock, Rac, and Arp2/3, spatially guides the growth of dendritic actin networks in pseudopods of eukaryotic cells during chemotaxis.
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Patel M, Pelletier A, Côté JF. Opening up on ELMO regulation: New insights into the control of Rac signaling by the DOCK180/ELMO complex. Small GTPases 2011; 2:268-275. [PMID: 22292130 DOI: 10.4161/sgtp.2.5.17716] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 08/12/2011] [Indexed: 11/19/2022] Open
Abstract
GTPases are central hubs for directing cytoskeletal reorganization and cell migration. The DOCK family enforces positive regulation of certain GTPases, leading to their activation in discrete areas of the cell. ELMO, a well-known DOCK180 binding partner, has been cast with the role of potentiating DOCK180-mediated Rac activation. Exactly how ELMO contributes to Rac signaling is only beginning to be understood. Here, we discuss our most recent research investigating ELMO regulation of the DOCK180/Rac pathway. Interestingly, we found that ELMO is autoinhibited via intramolecular contacts at basal levels and we explore the novel domains that we identified at the heart of the auto-regulatory switch. We propose that the closed ELMO molecule masks protein-protein interfaces or domains with novel uncharacterized function; cell stimulation and GTPase binding to ELMO is proposed to activate (open) the protein and/or target the ELMO/DOCK180 complex to the cell membrane. In this manner, promiscuous signaling/activity downstream of ELMO/DOCK180 can be controlled for both spatially and temporally. Additionally, we report new data highlighting that DOCK proteins can form heterodimers, and we discuss possible mechanisms that could be implicated in controlling the ELMO activation state.
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Affiliation(s)
- Manishha Patel
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, Canada
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