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Lamb H, Liro MJ, Myles KM, Fernholz M, Anderson HA, Rose LS. The Rac1 homolog CED-10 is a component of the MES-1/SRC-1 pathway for asymmetric division of the C. elegans EMS blastomere. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.04.588162. [PMID: 38645195 PMCID: PMC11030239 DOI: 10.1101/2024.04.04.588162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Asymmetric cell division is essential for the creation of cell types with different identities and functions. The EMS blastomere of the four-cell Caenorhabditis elegans embryo undergoes an asymmetric division in response to partially redundant signaling pathways. One pathway involves a Wnt signal emanating from the neighboring P2 cell, while the other pathway is defined by the receptor-like MES-1 protein localized at the EMS/P2 cell contact, and the cytoplasmic kinase SRC-1. In response to these pathways, the EMS nuclear-centrosome complex rotates so that the spindle forms on the anterior-posterior axis; after division, the daughter cell contacting P2 becomes the endodermal precursor cell. Here we identify the Rac1 homolog, CED-10, as a new component of the MES-1/SRC-1 pathway. Loss of CED-10 affects both spindle positioning and endoderm specification. Although MES-1 is still present at the EMS/P2 contact in ced-10 embryos, SRC-1 dependent phosphorylation is reduced. These and other results suggest that CED-10 acts downstream of MES-1 and upstream or at the level of SRC-1 activity. In addition, we find that the branched actin regulator ARX-2 is enriched at the EMS/P2 cell contact site, in a CED-10 dependent manner. Loss of ARX-2 results in spindle positioning defects, suggesting that CED-10 acts through branched actin to promote the asymmetric division of the EMS cell.
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2
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Martinek J, Cifrová P, Vosolsobě S, García-González J, Malínská K, Mauerová Z, Jelínková B, Krtková J, Sikorová L, Leaves I, Sparkes I, Schwarzerová K. ARP2/3 complex associates with peroxisomes to participate in pexophagy in plants. NATURE PLANTS 2023; 9:1874-1889. [PMID: 37845336 DOI: 10.1038/s41477-023-01542-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 09/11/2023] [Indexed: 10/18/2023]
Abstract
Actin-related protein (ARP2/3) complex is a heteroheptameric protein complex, evolutionary conserved in all eukaryotic organisms. Its conserved role is based on the induction of actin polymerization at the interface between membranes and the cytoplasm. Plant ARP2/3 has been reported to participate in actin reorganization at the plasma membrane during polarized growth of trichomes and at the plasma membrane-endoplasmic reticulum contact sites. Here we demonstrate that individual plant subunits of ARP2/3 fused to fluorescent proteins form motile spot-like structures in the cytoplasm that are associated with peroxisomes in Arabidopsis and tobacco. ARP2/3 is found at the peroxisome periphery and contains the assembled ARP2/3 complex and the WAVE/SCAR complex subunit NAP1. This ARP2/3-positive peroxisomal domain colocalizes with the autophagosome and, under conditions that affect the autophagy, colocalization between ARP2/3 and the autophagosome increases. ARP2/3 subunits co-immunoprecipitate with ATG8f and peroxisome-associated ARP2/3 interact in vivo with the ATG8f marker. Since mutants lacking functional ARP2/3 complex have more peroxisomes than wild type, we suggest that ARP2/3 has a novel role in the process of peroxisome degradation by autophagy, called pexophagy.
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Affiliation(s)
- Jan Martinek
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Petra Cifrová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Stanislav Vosolsobě
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Judith García-González
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Kateřina Malínská
- Imaging Facility of Institute of Experimental Botany AS CR, Prague, Czech Republic
| | - Zdeňka Mauerová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Barbora Jelínková
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jana Krtková
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Lenka Sikorová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Ian Leaves
- Biosciences, CLES, Exeter University, Exeter, UK
| | - Imogen Sparkes
- School of Biological Sciences, University of Bristol, Bristol, UK
| | - Kateřina Schwarzerová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic.
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3
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Ho J, Guerrero LA, Libuda DE, Luxton GWG, Starr DA. Actin and CDC-42 contribute to nuclear migration through constricted spaces in C. elegans. Development 2023; 150:dev202115. [PMID: 37756590 PMCID: PMC10617605 DOI: 10.1242/dev.202115] [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] [Received: 06/22/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023]
Abstract
Successful nuclear migration through constricted spaces between cells or in the extracellular matrix relies on the ability of the nucleus to deform. Little is known about how this takes place in vivo. We have studied confined nuclear migration in Caenorhabditis elegans larval P cells, which is mediated by the LINC complex to pull nuclei towards the minus ends of microtubules. Null mutations of the LINC component unc-84 lead to a temperature-dependent phenotype, suggesting a parallel pathway for P-cell nuclear migration. A forward genetic screen for enhancers of unc-84 identified cgef-1 (CDC-42 guanine nucleotide exchange factor). Knockdown of CDC-42 in the absence of the LINC complex led to a P-cell nuclear migration defect. Expression of constitutively active CDC-42 partially rescued nuclear migration in cgef-1; unc-84 double mutants, suggesting that CDC-42 functions downstream of CGEF-1. The Arp2/3 complex and non-muscle myosin II (NMY-2) were also found to function parallel to the LINC pathway. In our model, CGEF-1 activates CDC-42, which induces actin polymerization through the Arp2/3 complex to deform the nucleus during nuclear migration, and NMY-2 helps to push the nucleus through confined spaces.
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Affiliation(s)
- Jamie Ho
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Leslie A. Guerrero
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Diana E. Libuda
- Department of Biology, University of Oregon, Eugene, OR 97403, USA
| | - G. W. Gant Luxton
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Daniel A. Starr
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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4
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Geens E, Van de Walle P, Caroti F, Jelier R, Steuwe C, Schoofs L, Temmerman L. Yolk-deprived Caenorhabditis elegans secure brood size at the expense of competitive fitness. Life Sci Alliance 2023; 6:e202201675. [PMID: 37059473 PMCID: PMC10105328 DOI: 10.26508/lsa.202201675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 04/16/2023] Open
Abstract
Oviparous animals support reproduction via the incorporation of yolk as a nutrient source into the eggs. In Caenorhabditis elegans, however, yolk proteins seem dispensable for fecundity, despite constituting the vast majority of the embryonic protein pool and acting as carriers for nutrient-rich lipids. Here, we used yolk protein-deprived C. elegans mutants to gain insight into the traits that may yet be influenced by yolk rationing. We show that massive yolk provisioning confers a temporal advantage during embryogenesis, while also increasing early juvenile body size and promoting competitive fitness. Opposite to species that reduce egg production under yolk deprivation, our results indicate that C. elegans relies on yolk as a fail-safe to secure offspring survival, rather than to maintain offspring numbers.
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Affiliation(s)
- Ellen Geens
- Department of Biology, KU Leuven, Leuven, Belgium
| | | | - Francesca Caroti
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Rob Jelier
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Christian Steuwe
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
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5
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Xiao Y, Yee C, Zhao CZ, Martinez MAQ, Zhang W, Shen K, Matus DQ, Hammell C. An expandable FLP-ON::TIR1 system for precise spatiotemporal protein degradation in Caenorhabditis elegans. Genetics 2023; 223:iyad013. [PMID: 36722258 PMCID: PMC10319979 DOI: 10.1093/genetics/iyad013] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/16/2023] [Indexed: 02/02/2023] Open
Abstract
The auxin-inducible degradation system has been widely adopted in the Caenorhabditis elegans research community for its ability to empirically control the spatiotemporal expression of target proteins. This system can efficiently degrade auxin-inducible degron (AID)-tagged proteins via the expression of a ligand-activatable AtTIR1 protein derived from A. thaliana that adapts target proteins to the endogenous C. elegans proteasome. While broad expression of AtTIR1 using strong, ubiquitous promoters can lead to rapid degradation of AID-tagged proteins, cell type-specific expression of AtTIR1 using spatially restricted promoters often results in less efficient target protein degradation. To circumvent this limitation, we have developed an FLP/FRT3-based system that functions to reanimate a dormant, high-powered promoter that can drive sufficient AtTIR1 expression in a cell type-specific manner. We benchmark the utility of this system by generating a number of tissue-specific FLP-ON::TIR1 drivers to reveal genetically separable cell type-specific phenotypes for several target proteins. We also demonstrate that the FLP-ON::TIR1 system is compatible with enhanced degron epitopes. Finally, we provide an expandable toolkit utilizing the basic FLP-ON::TIR1 system that can be adapted to drive optimized AtTIR1 expression in any tissue or cell type of interest.
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Affiliation(s)
- Yutong Xiao
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Callista Yee
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Chris Z Zhao
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Michael A Q Martinez
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Wan Zhang
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Kang Shen
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
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6
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Genomic instability caused by Arp2/3 complex inactivation results in micronucleus biogenesis and cellular senescence. PLoS Genet 2023; 19:e1010045. [PMID: 36706133 PMCID: PMC9907832 DOI: 10.1371/journal.pgen.1010045] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/08/2023] [Accepted: 01/10/2023] [Indexed: 01/28/2023] Open
Abstract
The Arp2/3 complex is an actin nucleator with well-characterized activities in cell morphogenesis and movement, but its roles in nuclear processes are relatively understudied. We investigated how the Arp2/3 complex affects genomic integrity and cell cycle progression using mouse fibroblasts containing an inducible knockout (iKO) of the ArpC2 subunit. We show that permanent Arp2/3 complex ablation results in DNA damage, the formation of cytosolic micronuclei, and cellular senescence. Micronuclei arise in ArpC2 iKO cells due to chromatin segregation defects during mitosis and premature mitotic exits. Such phenotypes are explained by the presence of damaged DNA fragments that fail to attach to the mitotic spindle, abnormalities in actin assembly during metaphase, and asymmetric microtubule architecture during anaphase. In the nuclei of Arp2/3-depleted cells, the tumor suppressor p53 is activated and the cell cycle inhibitor Cdkn1a/p21 mediates a G1 arrest. In the cytosol, micronuclei are recognized by the DNA sensor cGAS, which is important for stimulating a STING- and IRF3-associated interferon response. These studies establish functional requirements for the mammalian Arp2/3 complex in mitotic spindle organization and genome stability. They also expand our understanding of the mechanisms leading to senescence and suggest that cytoskeletal dysfunction is an underlying factor in biological aging.
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7
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Yan VT, Narayanan A, Wiegand T, Jülicher F, Grill SW. A condensate dynamic instability orchestrates actomyosin cortex activation. Nature 2022; 609:597-604. [PMID: 35978196 PMCID: PMC9477739 DOI: 10.1038/s41586-022-05084-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 07/07/2022] [Indexed: 11/17/2022]
Abstract
A key event at the onset of development is the activation of a contractile actomyosin cortex during the oocyte-to-embryo transition1-3. Here we report on the discovery that, in Caenorhabditis elegans oocytes, actomyosin cortex activation is supported by the emergence of thousands of short-lived protein condensates rich in F-actin, N-WASP and the ARP2/3 complex4-8 that form an active micro-emulsion. A phase portrait analysis of the dynamics of individual cortical condensates reveals that condensates initially grow and then transition to disassembly before dissolving completely. We find that, in contrast to condensate growth through diffusion9, the growth dynamics of cortical condensates are chemically driven. Notably, the associated chemical reactions obey mass action kinetics that govern both composition and size. We suggest that the resultant condensate dynamic instability10 suppresses coarsening of the active micro-emulsion11, ensures reaction kinetics that are independent of condensate size and prevents runaway F-actin nucleation during the formation of the first cortical actin meshwork.
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Affiliation(s)
- Victoria Tianjing Yan
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany.,Biotechnology Center, TU Dresden, Dresden, Germany
| | - Arjun Narayanan
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany. .,Biotechnology Center, TU Dresden, Dresden, Germany. .,Max Planck Institute for the Physics of Complex Systems (MPI-PKS), Dresden, Germany. .,Center for Systems Biology Dresden (CSBD), Dresden, Germany.
| | - Tina Wiegand
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany.,Max Planck Institute for the Physics of Complex Systems (MPI-PKS), Dresden, Germany.,Center for Systems Biology Dresden (CSBD), Dresden, Germany
| | - Frank Jülicher
- Max Planck Institute for the Physics of Complex Systems (MPI-PKS), Dresden, Germany. .,Center for Systems Biology Dresden (CSBD), Dresden, Germany. .,Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany.
| | - Stephan W Grill
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany. .,Center for Systems Biology Dresden (CSBD), Dresden, Germany. .,Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany.
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8
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Martin E, Suzanne M. Functions of Arp2/3 Complex in the Dynamics of Epithelial Tissues. Front Cell Dev Biol 2022; 10:886288. [PMID: 35557951 PMCID: PMC9089454 DOI: 10.3389/fcell.2022.886288] [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: 02/28/2022] [Accepted: 04/01/2022] [Indexed: 11/13/2022] Open
Abstract
Epithelia are sheets of cells that communicate and coordinate their behavior in order to ensure their barrier function. Among the plethora of proteins involved in epithelial dynamics, actin nucleators play an essential role. The branched actin nucleation complex Arp2/3 has numerous functions, such as the regulation of cell-cell adhesion, intracellular trafficking, the formation of protrusions, that have been well described at the level of individual cells. Here, we chose to focus on its role in epithelial tissue, which is rising attention in recent works. We discuss how the cellular activities of the Arp2/3 complex drive epithelial dynamics and/or tissue morphogenesis. In the first part, we examined how this complex influences cell-cell cooperation at local scale in processes such as cell-cell fusion or cell corpses engulfment. In the second part, we summarized recent papers dealing with the impact of the Arp2/3 complex at larger scale, focusing on different morphogenetic events, including cell intercalation, epithelial tissue closure and epithelial folding. Altogether, this review highlights the central role of Arp2/3 in a diversity of epithelial tissue reorganization.
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Affiliation(s)
- Emmanuel Martin
- Molecular, Cellular and Developmental Biology (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Toulouse, France.,FR3743 Centre de Biologie Intégrative (CBI), Toulouse, France
| | - Magali Suzanne
- Molecular, Cellular and Developmental Biology (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Toulouse, France.,FR3743 Centre de Biologie Intégrative (CBI), Toulouse, France
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9
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Xu J, Meng X, Yang Q, Zhang J, Hu W, Fu H, Chen JW, Ma W, Chisholm AD, Sun Q, Xu S. Redox-sensitive CDC-42 clustering promotes wound closure in C. elegans. Cell Rep 2021; 37:110040. [PMID: 34818546 DOI: 10.1016/j.celrep.2021.110040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 09/09/2021] [Accepted: 11/01/2021] [Indexed: 10/19/2022] Open
Abstract
Tissue damage induces immediate-early signals, activating Rho small GTPases to trigger actin polymerization essential for later wound repair. However, how tissue damage is sensed to activate Rho small GTPases locally remains elusive. Here, we found that wounding the C. elegans epidermis induces rapid relocalization of CDC-42 into plasma membrane-associated clusters, which subsequently recruits WASP/WSP-1 to trigger actin polymerization to close the wound. In addition, wounding induces a local transient increase and subsequent reduction of H2O2, which negatively regulates the clustering of CDC-42 and wound closure. CDC-42 CAAX motif-mediated prenylation and polybasic region-mediated cation-phospholipid interaction are both required for its clustering. Cysteine residues participate in intermolecular disulfide bonds to reduce membrane association and are required for negative regulation of CDC-42 clustering by H2O2. Collectively, our findings suggest that H2O2-regulated fine-tuning of CDC-42 localization can create a distinct biomolecular cluster that facilitates rapid epithelial wound repair after injury.
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Affiliation(s)
- Jingxiu Xu
- Center for Stem Cell and Regenerative Medicine and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Xinan Meng
- Center for Stem Cell and Regenerative Medicine and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China; Zhejiang University-University of Edinburgh Institute, Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Qingxian Yang
- Center for Stem Cell and Regenerative Medicine and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Jianqin Zhang
- Department of Biochemistry and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Wei Hu
- Department of Cell Biology and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Hongying Fu
- Center for Stem Cell and Regenerative Medicine and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Jack Wei Chen
- Department of Cell Biology and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Weirui Ma
- Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Andrew D Chisholm
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Qiming Sun
- Department of Biochemistry and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Suhong Xu
- Center for Stem Cell and Regenerative Medicine and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China; Zhejiang University-University of Edinburgh Institute, Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou 310058, China.
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10
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Grimbert S, Mastronardi K, Richard V, Christensen R, Law C, Zardoui K, Fay D, Piekny A. Multi-tissue patterning drives anterior morphogenesis of the C. elegans embryo. Dev Biol 2021; 471:49-64. [PMID: 33309948 PMCID: PMC8597047 DOI: 10.1016/j.ydbio.2020.12.003] [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] [Received: 04/29/2020] [Revised: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 11/23/2022]
Abstract
Complex structures derived from multiple tissue types are challenging to study in vivo, and our knowledge of how cells from different tissues are coordinated is limited. Model organisms have proven invaluable for improving our understanding of how chemical and mechanical cues between cells from two different tissues can govern specific morphogenetic events. Here we used Caenorhabditis elegans as a model system to show how cells from three different tissues are coordinated to give rise to the anterior lumen. While some aspects of pharyngeal morphogenesis have been well-described, it is less clear how cells from the pharynx, epidermis and neuroblasts coordinate to define the location of the anterior lumen and supporting structures. Using various microscopy and software approaches, we define the movements and patterns of these cells during anterior morphogenesis. Projections from the anterior-most pharyngeal cells (arcade cells) provide the first visible markers for the location of the future lumen, and facilitate patterning of the surrounding neuroblasts. These neuroblast patterns control the rate of migration of the anterior epidermal cells, whereas the epidermal cells ultimately reinforce and control the position of the future lumen, as they must join with the pharyngeal cells for their epithelialization. Our studies are the first to characterize anterior morphogenesis in C. elegans in detail and should lay the framework for identifying how these different patterns are controlled at the molecular level.
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Affiliation(s)
- Stéphanie Grimbert
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada
| | - Karina Mastronardi
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada
| | - Victoria Richard
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada
| | - Ryan Christensen
- Laboratory of High Resolution Optical Imaging, NIH/NIBIB, 13 South Drive, Bethesda, MD, 20892, USA
| | - Christopher Law
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada
| | - Khashayar Zardoui
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada
| | - David Fay
- Department of Molecular Biology, University of Wyoming, 1000 E. University Ave., Laramie, WY, 82071, USA
| | - Alisa Piekny
- Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada.
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11
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Abstract
As multi-cellular organisms evolved from small clusters of cells to complex metazoans, biological tubes became essential for life. Tubes are typically thought of as mainly playing a role in transport, with the hollow space (lumen) acting as a conduit to distribute nutrients and waste, or for gas exchange. However, biological tubes also provide a platform for physiological, mechanical, and structural functions. Indeed, tubulogenesis is often a critical aspect of morphogenesis and organogenesis. C. elegans is made up of tubes that provide structural support and protection (the epidermis), perform the mechanical and enzymatic processes of digestion (the buccal cavity, pharynx, intestine, and rectum), transport fluids for osmoregulation (the excretory system), and execute the functions necessary for reproduction (the germline, spermatheca, uterus and vulva). Here we review our current understanding of the genetic regulation, molecular processes, and physical forces involved in tubulogenesis and morphogenesis of the epidermal, digestive and excretory systems in C. elegans.
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Affiliation(s)
- Daniel D Shaye
- Department of Physiology and Biophysics, University of Illinois at Chicago-College of Medicine, Chicago, IL, United States.
| | - Martha C Soto
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, United States.
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12
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Raduwan H, Sasidharan S, Burgos LC, Wallace AG, Soto MC. RhoGAP RGA-8 supports morphogenesis in C. elegans by polarizing epithelia. Biol Open 2020; 9:bio056911. [PMID: 33243762 PMCID: PMC7710025 DOI: 10.1242/bio.056911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 10/02/2020] [Indexed: 11/22/2022] Open
Abstract
CDC-42 regulation of non-muscle myosin/NMY-2 is required for polarity maintenance in the one-cell embryo of Caenorhabditis elegans CDC-42 and NMY-2 regulate polarity throughout embryogenesis, but their contribution to later events of morphogenesis are less understood. We have shown that epidermal enclosure requires the GTPase CED-10/Rac1 and WAVE/Scar complex, its effector, to promote protrusions that drive enclosure through the branch actin regulator Arp2/3. Our analysis here of RGA-8, a homolog of SH3BP1/Rich1/ARHGAP17/Nadrin, with BAR and RhoGAP motifs, suggests it regulates CDC-42, so that actin and myosin/NMY-2 promote ventral enclosure during embryonic morphogenesis. Genetic and molecular data suggest RGA-8 regulates CDC-42, and phenocopies the CDC-42 pathway regulators WASP-1/WSP-1 and the F-BAR proteins TOCA-1 and TOCA-2. Live imaging shows RGA-8 and WSP-1 enrich myosin and regulate F-actin in migrating epidermal cells during ventral enclosure. Loss of RGA-8 alters membrane recruitment of active CDC-42. We propose TOCA proteins and RGA-8 use BAR domains to localize and regenerate CDC-42 activity, thus regulating F-actin levels, through the branched actin regulator WSP-1, and myosin enrichment. RhoGAP RGA-8 thus polarizes epithelia, to promote cell migrations and cell shape changes of embryonic morphogenesis.
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Affiliation(s)
- Hamidah Raduwan
- Department of Pathology and Laboratory Medicine, Rutgers - RWJMS, Piscataway, NJ 08854, USA
- Cell and Developmental Biology Graduate Program, School of Graduate Studies, Rutgers - RWJMS, Piscataway, NJ 08854, USA
| | - Shashikala Sasidharan
- Department of Pathology and Laboratory Medicine, Rutgers - RWJMS, Piscataway, NJ 08854, USA
| | - Luigy Cordova Burgos
- Department of Pathology and Laboratory Medicine, Rutgers - RWJMS, Piscataway, NJ 08854, USA
| | - Andre G Wallace
- Department of Biological Sciences, Fairleigh Dickinson University, Teaneck, NJ 07666, USA
| | - Martha C Soto
- Department of Pathology and Laboratory Medicine, Rutgers - RWJMS, Piscataway, NJ 08854, USA
- Cell and Developmental Biology Graduate Program, School of Graduate Studies, Rutgers - RWJMS, Piscataway, NJ 08854, USA
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13
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Meng L, Yan D. NLR-1/CASPR Anchors F-Actin to Promote Gap Junction Formation. Dev Cell 2020; 55:574-587.e3. [PMID: 33238150 DOI: 10.1016/j.devcel.2020.10.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 08/05/2020] [Accepted: 10/28/2020] [Indexed: 12/31/2022]
Abstract
Gap junctions are present in most tissues and play essential roles in various biological processes. However, we know surprisingly little about the molecular mechanisms underlying gap junction formation. Here, we uncover the essential role of a conserved EGF- and laminin-G-domain-containing protein nlr-1/CASPR in the regulation of gap junction formation in multiple tissues across different developmental stages in C. elegans. NLR-1 is located in the gap junction perinexus, a region adjacent to but not overlapping with gap junctions, and forms puncta before the clusters of gap junction channels appear on the membrane. We show that NLR-1 can directly bind to actin to recruit F-actin networks at the gap junction formation plaque, and the formation of F-actin patches plays a critical role in the assembly of gap junction channels. Our findings demonstrate that nlr-1/CASPR acts as an early stage signal for gap junction formation through anchoring of F-actin networks.
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Affiliation(s)
- Lingfeng Meng
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Dong Yan
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Regeneration Next, and Duke Institute for Brain Sciences, Duke University Medical Center, Durham, NC 27710, USA.
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14
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Gordon KL, Zussman JW, Li X, Miller C, Sherwood DR. Stem cell niche exit in C. elegans via orientation and segregation of daughter cells by a cryptic cell outside the niche. eLife 2020; 9:e56383. [PMID: 32692313 PMCID: PMC7467730 DOI: 10.7554/elife.56383] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 07/17/2020] [Indexed: 12/17/2022] Open
Abstract
Stem cells reside in and rely upon their niche to maintain stemness but must balance self-renewal with the production of daughters that leave the niche to differentiate. We discovered a mechanism of stem cell niche exit in the canonical C. elegans distal tip cell (DTC) germ stem cell niche mediated by previously unobserved, thin, membranous protrusions of the adjacent somatic gonad cell pair (Sh1). A disproportionate number of germ cell divisions were observed at the DTC-Sh1 interface. Stem-like and differentiating cell fates segregated across this boundary. Spindles polarized, pairs of daughter cells oriented between the DTC and Sh1, and Sh1 grew over the Sh1-facing daughter. Impeding Sh1 growth by RNAi to cofilin and Arp2/3 perturbed the DTC-Sh1 interface, reduced germ cell proliferation, and shifted a differentiation marker. Because Sh1 membrane protrusions eluded detection for decades, it is possible that similar structures actively regulate niche exit in other systems.
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Affiliation(s)
- Kacy L Gordon
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
| | - Jay W Zussman
- Department of Biology, Duke UniversityDurhamUnited States
| | - Xin Li
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
| | - Camille Miller
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
| | - David R Sherwood
- Department of Biology, Duke UniversityDurhamUnited States
- Regeneration Next, Duke UniversityDurhamUnited States
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15
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Game of Tissues: How the Epidermis Thrones C. elegans Shape. J Dev Biol 2020; 8:jdb8010007. [PMID: 32182901 PMCID: PMC7151205 DOI: 10.3390/jdb8010007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 12/14/2022] Open
Abstract
The versatility of epithelial cell structure is universally exploited by organisms in multiple contexts. Epithelial cells can establish diverse polarized axes within their tridimensional structure which enables them to flexibly communicate with their neighbors in a 360° range. Hence, these cells are central to multicellularity, and participate in diverse biological processes such as organismal development, growth or immune response and their misfunction ultimately impacts disease. During the development of an organism, the first task epidermal cells must complete is the formation of a continuous sheet, which initiates its own morphogenic process. In this review, we will focus on the C. elegans embryonic epithelial morphogenesis. We will describe how its formation, maturation, and spatial arrangements set the final shape of the nematode C. elegans. Special importance will be given to the tissue-tissue interactions, regulatory tissue-tissue feedback mechanisms and the players orchestrating the process.
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16
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Taffoni C, Omi S, Huber C, Mailfert S, Fallet M, Rupprecht JF, Ewbank JJ, Pujol N. Microtubule plus-end dynamics link wound repair to the innate immune response. eLife 2020; 9:e45047. [PMID: 31995031 PMCID: PMC7043892 DOI: 10.7554/elife.45047] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 01/27/2020] [Indexed: 01/20/2023] Open
Abstract
The skin protects animals from infection and physical damage. In Caenorhabditis elegans, wounding the epidermis triggers an immune reaction and a repair response, but it is not clear how these are coordinated. Previous work implicated the microtubule cytoskeleton in the maintenance of epidermal integrity (Chuang et al., 2016). Here, by establishing a simple wounding system, we show that wounding provokes a reorganisation of plasma membrane subdomains. This is followed by recruitment of the microtubule plus end-binding protein EB1/EBP-2 around the wound and actin ring formation, dependent on ARP2/3 branched actin polymerisation. We show that microtubule dynamics are required for the recruitment and closure of the actin ring, and for the trafficking of the key signalling protein SLC6/SNF-12 toward the injury site. Without SNF-12 recruitment, there is an abrogation of the immune response. Our results suggest that microtubule dynamics coordinate the cytoskeletal changes required for wound repair and the concomitant activation of innate immunity.
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Affiliation(s)
- Clara Taffoni
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Shizue Omi
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Caroline Huber
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Sébastien Mailfert
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Mathieu Fallet
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | | | - Jonathan J Ewbank
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Nathalie Pujol
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
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17
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Wang S, Ochoa SD, Khaliullin RN, Gerson-Gurwitz A, Hendel JM, Zhao Z, Biggs R, Chisholm AD, Desai A, Oegema K, Green RA. A high-content imaging approach to profile C. elegans embryonic development. Development 2019; 146:dev174029. [PMID: 30890570 PMCID: PMC6467471 DOI: 10.1242/dev.174029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 03/11/2019] [Indexed: 11/20/2022]
Abstract
The Caenorhabditis elegans embryo is an important model for analyzing mechanisms of cell fate specification and tissue morphogenesis. Sophisticated lineage-tracing approaches for analyzing embryogenesis have been developed but are labor intensive and do not naturally integrate morphogenetic readouts. To enable the rapid classification of developmental phenotypes, we developed a high-content method that employs two custom strains: a Germ Layer strain that expresses nuclear markers in the ectoderm, mesoderm and endoderm/pharynx; and a Morphogenesis strain that expresses markers labeling epidermal cell junctions and the neuronal cell surface. We describe a procedure that allows simultaneous live imaging of development in 80-100 embryos and provide a custom program that generates cropped, oriented image stacks of individual embryos to facilitate analysis. We demonstrate the utility of our method by perturbing 40 previously characterized developmental genes in variants of the two strains containing RNAi-sensitizing mutations. The resulting datasets yielded distinct, reproducible signature phenotypes for a broad spectrum of genes that are involved in cell fate specification and morphogenesis. In addition, our analysis provides new in vivo evidence for MBK-2 function in mesoderm fate specification and LET-381 function in elongation.
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Affiliation(s)
- Shaohe Wang
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
- Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Stacy D Ochoa
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Renat N Khaliullin
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Adina Gerson-Gurwitz
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Jeffrey M Hendel
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Zhiling Zhao
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Ronald Biggs
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Andrew D Chisholm
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Arshad Desai
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Karen Oegema
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Rebecca A Green
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
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18
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Regulation of Actin Dynamics in the C. elegans Somatic Gonad. J Dev Biol 2019; 7:jdb7010006. [PMID: 30897735 PMCID: PMC6473838 DOI: 10.3390/jdb7010006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 03/13/2019] [Accepted: 03/15/2019] [Indexed: 11/25/2022] Open
Abstract
The reproductive system of the hermaphroditic nematode C. elegans consists of a series of contractile cell types—including the gonadal sheath cells, the spermathecal cells and the spermatheca–uterine valve—that contract in a coordinated manner to regulate oocyte entry and exit of the fertilized embryo into the uterus. Contraction is driven by acto-myosin contraction and relies on the development and maintenance of specialized acto-myosin networks in each cell type. Study of this system has revealed insights into the regulation of acto-myosin network assembly and contractility in vivo.
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19
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Kelley LC, Chi Q, Cáceres R, Hastie E, Schindler AJ, Jiang Y, Matus DQ, Plastino J, Sherwood DR. Adaptive F-Actin Polymerization and Localized ATP Production Drive Basement Membrane Invasion in the Absence of MMPs. Dev Cell 2019; 48:313-328.e8. [PMID: 30686527 PMCID: PMC6372315 DOI: 10.1016/j.devcel.2018.12.018] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 11/07/2018] [Accepted: 12/20/2018] [Indexed: 12/21/2022]
Abstract
Matrix metalloproteinases (MMPs) are associated with decreased patient prognosis but have failed as anti-invasive drug targets despite promoting cancer cell invasion. Through time-lapse imaging, optical highlighting, and combined genetic removal of the five MMPs expressed during anchor cell (AC) invasion in C. elegans, we find that MMPs hasten invasion by degrading basement membrane (BM). Though irregular and delayed, AC invasion persists in MMP- animals via adaptive enrichment of the Arp2/3 complex at the invasive cell membrane, which drives formation of an F-actin-rich protrusion that physically breaches and displaces BM. Using a large-scale RNAi synergistic screen and a genetically encoded ATP FRET sensor, we discover that mitochondria enrich within the protrusion and provide localized ATP that fuels F-actin network growth. Thus, without MMPs, an invasive cell can alter its BM-breaching tactics, suggesting that targeting adaptive mechanisms will be necessary to mitigate BM invasion in human pathologies.
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Affiliation(s)
- Laura C Kelley
- Department of Biology, Regeneration Next, Duke University, Box 90338, Durham, NC 27708, USA
| | - Qiuyi Chi
- Department of Biology, Regeneration Next, Duke University, Box 90338, Durham, NC 27708, USA
| | - Rodrigo Cáceres
- CNRS, Laboratoire Physico Chimie Curie, Institut Curie, PSL Research Université, Paris 75005, France; Sorbonne Université, Paris 75005, France; Université Paris Descartes, Sorbonne Paris Cité, Paris 75005, France
| | - Eric Hastie
- Department of Biology, Regeneration Next, Duke University, Box 90338, Durham, NC 27708, USA
| | - Adam J Schindler
- Department of Biology, Regeneration Next, Duke University, Box 90338, Durham, NC 27708, USA
| | - Yue Jiang
- Department of Biology, Regeneration Next, Duke University, Box 90338, Durham, NC 27708, USA
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Julie Plastino
- CNRS, Laboratoire Physico Chimie Curie, Institut Curie, PSL Research Université, Paris 75005, France; Sorbonne Université, Paris 75005, France
| | - David R Sherwood
- Department of Biology, Regeneration Next, Duke University, Box 90338, Durham, NC 27708, USA.
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20
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Cáceres R, Bojanala N, Kelley LC, Dreier J, Manzi J, Di Federico F, Chi Q, Risler T, Testa I, Sherwood DR, Plastino J. Forces drive basement membrane invasion in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2018; 115:11537-11542. [PMID: 30348801 PMCID: PMC6233148 DOI: 10.1073/pnas.1808760115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
During invasion, cells breach basement membrane (BM) barriers with actin-rich protrusions. It remains unclear, however, whether actin polymerization applies pushing forces to help break through BM, or whether actin filaments play a passive role as scaffolding for targeting invasive machinery. Here, using the developmental event of anchor cell (AC) invasion in Caenorhabditis elegans, we observe that the AC deforms the BM and underlying tissue just before invasion, exerting forces in the tens of nanonewtons range. Deformation is driven by actin polymerization nucleated by the Arp2/3 complex and its activators, whereas formins and cross-linkers are dispensable. Delays in invasion upon actin regulator loss are not caused by defects in AC polarity, trafficking, or secretion, as appropriate markers are correctly localized in the AC even when actin is reduced and invasion is disrupted. Overall force production emerges from this study as one of the main tools that invading cells use to promote BM disruption in C. elegans.
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Affiliation(s)
- Rodrigo Cáceres
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, CNRS, 75005 Paris, France
- Université Paris Descartes, 75005 Paris, France
- Sorbonne Université, 75005 Paris, France
| | - Nagagireesh Bojanala
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, CNRS, 75005 Paris, France
- Sorbonne Université, 75005 Paris, France
| | - Laura C Kelley
- Department of Biology, Regeneration Next, Duke University, Durham, NC 27705
| | - Jes Dreier
- Department of Applied Physics and Science for Life Laboratory, KTH Royal Institute of Technology, 10014 Stockholm, Sweden
| | - John Manzi
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, CNRS, 75005 Paris, France
- Sorbonne Université, 75005 Paris, France
| | - Fahima Di Federico
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, CNRS, 75005 Paris, France
- Sorbonne Université, 75005 Paris, France
| | - Qiuyi Chi
- Department of Biology, Regeneration Next, Duke University, Durham, NC 27705
| | - Thomas Risler
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, CNRS, 75005 Paris, France
- Sorbonne Université, 75005 Paris, France
| | - Ilaria Testa
- Department of Applied Physics and Science for Life Laboratory, KTH Royal Institute of Technology, 10014 Stockholm, Sweden
| | - David R Sherwood
- Department of Biology, Regeneration Next, Duke University, Durham, NC 27705
| | - Julie Plastino
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, CNRS, 75005 Paris, France;
- Sorbonne Université, 75005 Paris, France
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21
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Maheshwari D, Shukla VK, Jain A, Tripathi S, Kumar D, Arora A. Solution structure and dynamics of glia maturation factor from Caenorhabditis elegans. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1866:1008-1020. [PMID: 29981887 DOI: 10.1016/j.bbapap.2018.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 06/11/2018] [Accepted: 06/27/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND The GMF class of the ADF-H domain family proteins regulate actin dynamics by binding to the Arp2/3 complex and F-actin through their Site-1 and Site-2, respectively. CeGMF of C. elegans is analogous to GMFγ of human and mouse and is 138 amino acids in length. METHODS We have characterized the solution structure and dynamics of CeGMF by solution NMR spectroscopy and its thermal stability by DSC. RESULTS The solution structure of CeGMF shows canonical ADF-H fold with two additional β-strands in the β4-β5 loop region. The Site-1 of CeGMF is well formed and residues of all three regions of Site-1 show dynamic flexibility. However, the β4-β5 loop of Site-2 is less inclined towards the C-terminal, as the latter is truncated by four residues in comparison to GMF isoforms of human and mouse. Regions of Site-2 show motions on ns-ps timescale, but dynamic flexibility of β4-β5 loop is low in comparison to corresponding F-loop region of ADF/cofilin UNC-60B. A general difference in packing of α3 and α1 between GMF and ADF/cofilins was noticed. Additionally, thermal stability of CeGMF was significantly higher than its ADF/cofilin homologs. CONCLUSION We have presented the first solution structure of GMF from C. elegans, which highlights the structural differences between the Site-2 of CeGMF and mammalian GMF isoforms. Further, we have seen the differences in structure, dynamics, and thermal stability of GMF and ADF/cofilin. GENERAL SIGNIFICANCE This study provides a useful insight to structural and dynamics factors that define the specificity of GMF towards Arp2/3 complex.
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Affiliation(s)
- Diva Maheshwari
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India; Academy of Scientific and Innovative Research, New Delhi 110025, India
| | - Vaibhav Kumar Shukla
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Anupam Jain
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Sarita Tripathi
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Dinesh Kumar
- Centre of Biomedical Research (CBMR), Sanjay Gandhi Post-Graduate Institute of Medical Sciences, Raibareli Road, Lucknow, Uttar Pradesh 226014, India
| | - Ashish Arora
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India; Academy of Scientific and Innovative Research, New Delhi 110025, India.
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22
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Tissue-Specific Functions of fem-2/PP2c Phosphatase and fhod-1/formin During Caenorhabditis elegans Embryonic Morphogenesis. G3-GENES GENOMES GENETICS 2018; 8:2277-2290. [PMID: 29720391 PMCID: PMC6027879 DOI: 10.1534/g3.118.200274] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The cytoskeleton is the basic machinery that drives many morphogenetic events. Elongation of the C. elegans embryo from a spheroid into a long, thin larva initially results from actomyosin contractility, mainly in the lateral epidermal seam cells, while the corresponding dorsal and ventral epidermal cells play a more passive role. This is followed by a later elongation phase involving muscle contraction. Early elongation is mediated by parallel genetic pathways involving LET-502/Rho kinase and MEL-11/MYPT myosin phosphatase in one pathway and FEM-2/PP2c phosphatase and PAK-1/p21 activated kinase in another. While the LET-502/MEL-11 pathway appears to act primarily in the lateral epidermis, here we show that FEM-2 can mediate early elongation when expressed in the dorsal and ventral epidermis. We also investigated the early elongation function of FHOD-1, a member of the formin family of actin nucleators and bundlers. Previous work showed that FHOD-1 acts in the LET-502/MEL-11 branch of the early elongation pathway as well as in muscle for sarcomere organization. Consistent with this, we found that lateral epidermal cell-specific expression of FHOD-1 is sufficient for elongation, and FHOD-1 effects on elongation appear to be independent of its role in muscle. Also, we found that fhod-1 encodes long and short isoforms that differ in the presence of a predicted coiled-coil domain. Based on tissue-specific expression constructions and an isoform-specific CRISPR allele, the two FHOD-1 isoforms show partially specialized epidermal or muscle function. Although fhod-1 shows only impenetrant elongation phenotypes, we were unable to detect redundancy with other C. elegans formin genes.
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23
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Sherwood DR, Plastino J. Invading, Leading and Navigating Cells in Caenorhabditis elegans: Insights into Cell Movement in Vivo. Genetics 2018; 208:53-78. [PMID: 29301948 PMCID: PMC5753875 DOI: 10.1534/genetics.117.300082] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 10/26/2017] [Indexed: 12/30/2022] Open
Abstract
Highly regulated cell migration events are crucial during animal tissue formation and the trafficking of cells to sites of infection and injury. Misregulation of cell movement underlies numerous human diseases, including cancer. Although originally studied primarily in two-dimensional in vitro assays, most cell migrations in vivo occur in complex three-dimensional tissue environments that are difficult to recapitulate in cell culture or ex vivo Further, it is now known that cells can mobilize a diverse repertoire of migration modes and subcellular structures to move through and around tissues. This review provides an overview of three distinct cellular movement events in Caenorhabditis elegans-cell invasion through basement membrane, leader cell migration during organ formation, and individual cell migration around tissues-which together illustrate powerful experimental models of diverse modes of movement in vivo We discuss new insights into migration that are emerging from these in vivo studies and important future directions toward understanding the remarkable and assorted ways that cells move in animals.
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Affiliation(s)
- David R Sherwood
- Department of Biology, Regeneration Next, Duke University, Durham, North Carolina 27705
| | - Julie Plastino
- Institut Curie, PSL Research University, CNRS, UMR 168, F-75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 168, F-75005 Paris, France
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24
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Ghosh S, Vetrone SA, Sternberg PW. Non-neuronal cell outgrowth in C. elegans. WORM 2017; 6:e1405212. [PMID: 29238627 DOI: 10.1080/21624054.2017.1405212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 10/26/2017] [Accepted: 10/30/2017] [Indexed: 10/18/2022]
Abstract
Cell outgrowth is a hallmark of some non-migratory developing cells during morphogenesis. Understanding the mechanisms that control cell outgrowth not only increases our knowledge of tissue and organ development, but can also shed light on disease pathologies that exhibit outgrowth-like behavior. C. elegans is a highly useful model for the analysis of genes and the function of their respective proteins. In addition, C. elegans also has several cells and tissues that undergo outgrowth during development. Here we discuss the outgrowth mechanisms of nine different C. elegans cells and tissues. We specifically focus on how these cells and tissues grow outward and the interactions they make with their environment. Through our own identification, and a meta-analysis, we also identify gene families involved in multiple cell outgrowth processes, which defined potential C. elegans core components of cell outgrowth, as well as identify a potential stepwise cell behavioral cascade used by cells undergoing outgrowth.
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Affiliation(s)
- Srimoyee Ghosh
- Division of Biology and Biological Engineering and Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA
| | | | - Paul W Sternberg
- Division of Biology and Biological Engineering and Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA
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25
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Tian B, Li J, Oakley TR, Todd TC, Trick HN. Host-Derived Artificial MicroRNA as an Alternative Method to Improve Soybean Resistance to Soybean Cyst Nematode. Genes (Basel) 2016; 7:E122. [PMID: 27941644 PMCID: PMC5192498 DOI: 10.3390/genes7120122] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/17/2016] [Accepted: 12/01/2016] [Indexed: 11/23/2022] Open
Abstract
The soybean cyst nematode (SCN), Heterodera glycines, is one of the most important pests limiting soybean production worldwide. Novel approaches to managing this pest have focused on gene silencing of target nematode sequences using RNA interference (RNAi). With the discovery of endogenous microRNAs as a mode of gene regulation in plants, artificial microRNA (amiRNA) methods have become an alternative method for gene silencing, with the advantage that they can lead to more specific silencing of target genes than traditional RNAi vectors. To explore the application of amiRNAs for improving soybean resistance to SCN, three nematode genes (designated as J15, J20, and J23) were targeted using amiRNA vectors. The transgenic soybean hairy roots, transformed independently with these three amiRNA vectors, showed significant reductions in SCN population densities in bioassays. Expression of the targeted genes within SCN eggs were downregulated in populations feeding on transgenic hairy roots. Our results provide evidence that host-derived amiRNA methods have great potential to improve soybean resistance to SCN. This approach should also limit undesirable phenotypes associated with off-target effects, which is an important consideration for commercialization of transgenic crops.
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Affiliation(s)
- Bin Tian
- Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA.
| | - Jiarui Li
- Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA.
- Bayer CropScience, 3500 Paramount Pkwy, Morrisville, NC 27560, USA.
| | - Thomas R Oakley
- Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA.
| | - Timothy C Todd
- Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA.
| | - Harold N Trick
- Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA.
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RNAi Screen Identifies Novel Regulators of RNP Granules in the Caenorhabditis elegans Germ Line. G3-GENES GENOMES GENETICS 2016; 6:2643-54. [PMID: 27317775 PMCID: PMC4978917 DOI: 10.1534/g3.116.031559] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Complexes of RNA and RNA binding proteins form large-scale supramolecular structures under many cellular contexts. In Caenorhabditis elegans, small germ granules are present in the germ line that share characteristics with liquid droplets that undergo phase transitions. In meiotically-arrested oocytes of middle-aged hermaphrodites, the germ granules appear to aggregate or condense into large assemblies of RNA-binding proteins and maternal mRNAs. Prior characterization of the assembly of large-scale RNP structures via candidate approaches has identified a small number of regulators of phase transitions in the C. elegans germ line; however, the assembly, function, and regulation of these large RNP assemblies remain incompletely understood. To identify genes that promote remodeling and assembly of large RNP granules in meiotically-arrested oocytes, we performed a targeted, functional RNAi screen and identified over 300 genes that regulate the assembly of the RNA-binding protein MEX-3 into large granules. Among the most common GO classes are several categories related to RNA biology, as well as novel categories such as cell cortex, ER, and chromosome segregation. We found that arrested oocytes that fail to localize MEX-3 into cortical granules display reduced oocyte quality, consistent with the idea that the larger RNP assemblies promote oocyte quality when fertilization is delayed. Interestingly, a relatively small number of genes overlap with the regulators of germ granule assembly during normal development, or with the regulators of solid RNP granules in cgh-1 oocytes, suggesting fundamental differences in the regulation of RNP granule phase transitions during meiotic arrest.
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Walck-Shannon E, Hardin J. Another morphogenetic movement on the map: Charting dorsal intercalation in C. elegans. WORM 2016; 5:e1176664. [PMID: 27385264 DOI: 10.1080/21624054.2016.1176664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/05/2016] [Indexed: 12/26/2022]
Abstract
Dorsal intercalation is a coordinated cell migration event that rearranges hypodermal cells during C. elegans embryogenesis, and that resembles cell intercalation in many systems from flies to mice. Despite its conservation, the molecular mechanisms that govern dorsal intercalation in worms have remained elusive. Here, we comment on our recent publication, Walck-Shannon et al.,(1) which begins to spatially map the molecular requirements for intercalation. First, we provide a historical perspective on the factors that have previously hampered the study of dorsal intercalation. Next, we provide a summary of the molecular pathways identified in Walck-Shannon et al.,(1) pointing out surprises along the way. Finally, we consider the potential conservation of the molecular pathway we described and discuss future questions surrounding dorsal intercalation. Despite the challenges, dorsal intercalation is a process poised to advance our understanding of cell intercalation during morphogenesis throughout the animal kingdom.
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Affiliation(s)
| | - Jeff Hardin
- Department of Zoology, University of Wisconsin-Madison , Madison, WI, USA
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Ouellette MH, Martin E, Lacoste-Caron G, Hamiche K, Jenna S. Spatial control of active CDC-42 during collective migration of hypodermal cells in Caenorhabditis elegans. J Mol Cell Biol 2015; 8:313-27. [PMID: 26578656 DOI: 10.1093/jmcb/mjv062] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 08/12/2015] [Indexed: 12/11/2022] Open
Abstract
Collective epithelial cell migration requires the maintenance of cell-cell junctions while enabling the generation of actin-rich protrusions at the leading edge of migrating cells. Ventral enclosure of Caenorhabditis elegans embryos depends on the collective migration of anterior-positioned leading hypodermal cells towards the ventral midline where they form new junctions with their contralateral neighbours. In this study, we characterized the zygotic function of RGA-7/SPV-1, a CDC-42/Cdc42 and RHO-1/RhoA-specific Rho GTPase-activating protein, which controls the formation of actin-rich protrusions at the leading edge of leading hypodermal cells and the formation of new junctions between contralateral cells. We show that RGA-7 controls these processes in an antagonistic manner with the CDC-42's effector WSP-1/N-WASP and the CDC-42-binding proteins TOCA-1/2/TOCA1. RGA-7 is recruited to spatially distinct locations at junctions between adjacent leading cells, where it promotes the accumulation of clusters of activated CDC-42. It also inhibits the spreading of these clusters towards the leading edge of the junctions and regulates their accumulation and distribution at new junctions formed between contralateral leading cells. Our study suggests that RGA-7 controls collective migration and junction formation between epithelial cells by spatially restricting active CDC-42 within cell-cell junctions.
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Affiliation(s)
- Marie-Hélène Ouellette
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Emmanuel Martin
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Germain Lacoste-Caron
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Karim Hamiche
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Sarah Jenna
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal, Montréal, Québec, Canada
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Walck-Shannon E, Reiner D, Hardin J. Polarized Rac-dependent protrusions drive epithelial intercalation in the embryonic epidermis of C. elegans. Development 2015; 142:3549-60. [PMID: 26395474 DOI: 10.1242/dev.127597] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 08/26/2015] [Indexed: 12/24/2022]
Abstract
Cell intercalation is a fundamental, coordinated cell rearrangement process that shapes tissues throughout animal development. Studies of intercalation within epithelia have focused almost exclusively on the localized constriction of specific apical junctions. Another widely deployed yet poorly understood alternative mechanism of epithelial intercalation relies on basolateral protrusive activity. Using the dorsal embryonic epidermis of Caenorhabditis elegans, we have investigated this alternative mechanism using high-resolution live cell microscopy and genetic analysis. We find that as dorsal epidermal cells migrate past one another they produce F-actin-rich protrusions polarized at their extending (medial) edges. These protrusions are controlled by the C. elegans Rac and RhoG orthologs CED-10 and MIG-2, which function redundantly to polarize actin polymerization upstream of the WAVE complex and WASP, respectively. We also identify UNC-73, the C. elegans ortholog of Trio, as a guanine nucleotide exchange factor (GEF) upstream of both CED-10 and MIG-2. Further, we identify a novel polarizing cue, CRML-1, which is the ortholog of human capping Arp2/3 myosin I linker (CARMIL), that localizes to the nonprotrusive lateral edges of dorsal cells. CRML-1 genetically suppresses UNC-73 function and, indirectly, actin polymerization. This network identifies a novel, molecularly conserved cassette that regulates epithelial intercalation via basolateral protrusive activity.
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Affiliation(s)
- Elise Walck-Shannon
- Graduate Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson Street, Madison, WI 53706, USA
| | - David Reiner
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, 101 Manning Drive, Chapel Hill, NC 27514, USA Center for Translational Cancer Research, Institute of Biosciences and Technology and Department of Medical Physiology, Texas A&M Health Science Center, 2121 W. Holcombe Boulevard, Houston, TX 77030, USA
| | - Jeff Hardin
- Graduate Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson Street, Madison, WI 53706, USA Department of Zoology, University of Wisconsin-Madison, 1117 W. Johnson Street, Madison, WI 53706, USA
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Ho VWS, Wong MK, An X, Guan D, Shao J, Ng HCK, Ren X, He K, Liao J, Ang Y, Chen L, Huang X, Yan B, Xia Y, Chan LLH, Chow KL, Yan H, Zhao Z. Systems-level quantification of division timing reveals a common genetic architecture controlling asynchrony and fate asymmetry. Mol Syst Biol 2015; 11:814. [PMID: 26063786 PMCID: PMC4501849 DOI: 10.15252/msb.20145857] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Coordination of cell division timing is crucial for proper cell fate specification and tissue growth. However, the differential regulation of cell division timing across or within cell types during metazoan development remains poorly understood. To elucidate the systems-level genetic architecture coordinating division timing, we performed a high-content screening for genes whose depletion produced a significant reduction in the asynchrony of division between sister cells (ADS) compared to that of wild-type during Caenorhabditis elegans embryogenesis. We quantified division timing using 3D time-lapse imaging followed by computer-aided lineage analysis. A total of 822 genes were selected for perturbation based on their conservation and known roles in development. Surprisingly, we find that cell fate determinants are not only essential for establishing fate asymmetry, but also are imperative for setting the ADS regardless of cellular context, indicating a common genetic architecture used by both cellular processes. The fate determinants demonstrate either coupled or separate regulation between the two processes. The temporal coordination appears to facilitate cell migration during fate specification or tissue growth. Our quantitative dataset with cellular resolution provides a resource for future analyses of the genetic control of spatial and temporal coordination during metazoan development.
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Affiliation(s)
- Vincy Wing Sze Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Ming-Kin Wong
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaomeng An
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Daogang Guan
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Jiaofang Shao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Hon Chun Kaoru Ng
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Kan He
- Department of Biology, Hong Kong Baptist University, Hong Kong, China Center for Stem Cell and Translational Medicine, School of Life Sciences Anhui University, Hefei, China
| | - Jinyue Liao
- Division of Life Science and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yingjin Ang
- Division of Life Science and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Long Chen
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Xiaotai Huang
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Bin Yan
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Yiji Xia
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Leanne Lai Hang Chan
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - King Lau Chow
- Division of Life Science and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Hong Yan
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong, China
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Guanine nucleotide exchange factor OSG-1 confers functional aging via dysregulated Rho signaling in Caenorhabditis elegans neurons. Genetics 2014; 199:487-96. [PMID: 25527286 DOI: 10.1534/genetics.114.173500] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Rho signaling regulates a variety of biological processes, but whether it is implicated in aging remains an open question. Here we show that a guanine nucleotide exchange factor of the Dbl family, OSG-1, confers functional aging by dysregulating Rho GTPases activities in C. elegans. Thus, gene reporter analysis revealed widespread OSG-1 expression in muscle and neurons. Loss of OSG-1 gene function was not associated with developmental defects. In contrast, suppression of OSG-1 lessened loss of function (chemotaxis) in ASE sensory neurons subjected to conditions of oxidative stress generated during natural aging, by oxidative challenges, or by genetic mutations. RNAi analysis showed that OSG-1 was specific toward activation of RHO-1 GTPase signaling. RNAi further implicated actin-binding proteins ARX-3 and ARX-5, thus the actin cytoskeleton, as one of the targets of OSG-1/RHO-1 signaling. Taken together these data suggest that OSG-1 is recruited under conditions of oxidative stress, a hallmark of aging, and contributes to promote loss of neuronal function by affecting the actin cytoskeleton via altered RHO-1 activity.
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Abstract
An exciting frontier in biology is understanding the functions of basic cell biological machinery in complex tissues. This approach is expected to uncover novel modes of regulation as well as reveal how core machinery is repurposed by different tissues to accomplish different physiological outputs. F-actin plays roles in cell shape, adhesion, migration and signaling – diverse functions that require a specific organization established by a myriad of regulators. Here, we discuss the role of the actin nucleating Arp2/3 complex and the unexpected roles that it plays in a stratified epithelial tissue, the epidermis. While many expected phenotypes such as defects in architecture and cell adhesion were lacking, loss of the Arp2/3 complex activity resulted in epidermal barrier and differentiation defects. This teaches us that, while informative, cell culture approaches are limiting and that studies of the Arp2/3 complex in diverse tissues are expected to yield many more surprises.
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Affiliation(s)
- Terry Lechler
- Departments of Dermatology and Cell Biology, Duke University ; Durham, NC USA
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34
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Koumandou VL, Wickstead B, Ginger ML, van der Giezen M, Dacks JB, Field MC. Molecular paleontology and complexity in the last eukaryotic common ancestor. Crit Rev Biochem Mol Biol 2014; 48:373-96. [PMID: 23895660 PMCID: PMC3791482 DOI: 10.3109/10409238.2013.821444] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Eukaryogenesis, the origin of the eukaryotic cell, represents one of the fundamental evolutionary transitions in the history of life on earth. This event, which is estimated to have occurred over one billion years ago, remains rather poorly understood. While some well-validated examples of fossil microbial eukaryotes for this time frame have been described, these can provide only basic morphology and the molecular machinery present in these organisms has remained unknown. Complete and partial genomic information has begun to fill this gap, and is being used to trace proteins and cellular traits to their roots and to provide unprecedented levels of resolution of structures, metabolic pathways and capabilities of organisms at these earliest points within the eukaryotic lineage. This is essentially allowing a molecular paleontology. What has emerged from these studies is spectacular cellular complexity prior to expansion of the eukaryotic lineages. Multiple reconstructed cellular systems indicate a very sophisticated biology, which by implication arose following the initial eukaryogenesis event but prior to eukaryotic radiation and provides a challenge in terms of explaining how these early eukaryotes arose and in understanding how they lived. Here, we provide brief overviews of several cellular systems and the major emerging conclusions, together with predictions for subsequent directions in evolution leading to extant taxa. We also consider what these reconstructions suggest about the life styles and capabilities of these earliest eukaryotes and the period of evolution between the radiation of eukaryotes and the eukaryogenesis event itself.
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Affiliation(s)
- V Lila Koumandou
- Biomedical Research Foundation, Academy of Athens, Soranou Efesiou 4, Athens 115 27, Greece
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35
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Wicki-Stordeur LE, Swayne LA. The emerging Pannexin 1 signalome: a new nexus revealed? Front Cell Neurosci 2014; 7:287. [PMID: 24409119 PMCID: PMC3884145 DOI: 10.3389/fncel.2013.00287] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 12/23/2013] [Indexed: 11/22/2022] Open
Abstract
Pannexins (Panxs) are a family of single-membrane, large-pore ion, and metabolite permeable channels. Of the three Panx proteins, Panx1 has been most extensively studied, and has recently emerged as an exciting, clinically relevant target in many physiological and pathophysiological settings. This channel is widely expressed across various cell and tissue types; however its links to precise signaling pathways are largely unknown. Here we review the current literature surrounding presently identified Panx1–protein interactions, a critical first step to unraveling the Panx1 signalome. First we elucidate the reported associations of Panx1 with other ion channels, receptors, and channel signaling complexes. Further, we highlight recently identified Panx1–cytoskeleton interactions. Finally, we discuss the implications of these protein–protein interactions for Panx1 function in various cell and tissue types, and identify key outstanding questions arising from this work.
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Affiliation(s)
| | - Leigh A Swayne
- Division of Medical Sciences, University of Victoria Victoria, BC, Canada ; Department of Biology, University of Victoria Victoria, BC, Canada ; Department of Biochemistry and Microbiology, University of Victoria Victoria, BC, Canada ; Department of Cellular and Physiological Sciences and Island Medical Program, University of British Columbia Vancouver, BC, Canada
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Caenorhabditis elegans anillin (ani-1) regulates neuroblast cytokinesis and epidermal morphogenesis during embryonic development. Dev Biol 2013; 383:61-74. [DOI: 10.1016/j.ydbio.2013.08.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Revised: 08/24/2013] [Accepted: 08/27/2013] [Indexed: 11/23/2022]
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Wicki-Stordeur LE, Swayne LA. Panx1 regulates neural stem and progenitor cell behaviours associated with cytoskeletal dynamics and interacts with multiple cytoskeletal elements. Cell Commun Signal 2013; 11:62. [PMID: 23964896 PMCID: PMC3765679 DOI: 10.1186/1478-811x-11-62] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 08/19/2013] [Indexed: 11/25/2022] Open
Abstract
Background Pannexins (Panxs) are relatively newly discovered large-pore ion and metabolite permeable channels. Although no proteomics-based interactome has yet been published, Panx1 has been demonstrated to interact with actin in an ectopic expression system. This interaction affects both Panx1 plasma membrane stability as well as cytoskeletal remodelling. The current study builds on our recent discovery of Panx1 expression in ventricular zone (VZ) neural stem and progenitor cells (NSC/NPCs), and on the demonstrated interaction of Panx1 with the cytoskeleton. Findings Here we demonstrate that Panx1 also plays roles in two additional cell behaviours associated with neurogenesis, including cell migration and neurite extension. Furthermore, we confirm an endogenous interaction between actin and Panx1, and identify a new interaction with actin-related protein 3, an actin cytoskeleton-modulating protein. Conclusions This study further establishes the importance of Panx1 in the cell biology of NSC/NPCs and strengthens and expands our knowledge of Panx1 interactions with the cytoskeleton.
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Affiliation(s)
- Leigh E Wicki-Stordeur
- Division of Medical Sciences, Island Medical Program, University of Victoria, Victoria, British Columbia, Canada
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38
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Liu Z, Yang X, Chen C, Liu B, Ren B, Wang L, Zhao K, Yu S, Ming H. Expression of the Arp2/3 complex in human gliomas and its role in the migration and invasion of glioma cells. Oncol Rep 2013; 30:2127-36. [PMID: 23969835 DOI: 10.3892/or.2013.2669] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 07/25/2013] [Indexed: 11/06/2022] Open
Abstract
A hallmark of directional cell migration is localized actin polymerization at the leading protrusions of the cell. The Arp2/3 complex nucleates the formation of the dendritic actin network (lamellipodia) at the leading edge of motile cells. This study was designed to investigate the role of the Arp2/3 complex in the infiltrative behavior of glioma cells. Immunofluorescence and western blotting showed a positive correlation between the expression of Arp2/3 and the malignancy of glioma specimens (r=0.686, P=0.02) and confocal microscopy demonstrated localization of the Arp2/3 complex in lamellipodia of glioma cells. Furthermore, we examined the effects of Arp2/3 complex inhibition in U251, LN229 and SNB19 glioma cells using CK666, an Arp2/3 complex inhibitor. Glioma cells lost lamellipodia and cell polarity after treatment with CK666. Inhibition of the Arp2/3 complex significantly affected the ability of glioma cells to migrate and invade. In the wound-healing assay, CK666 markedly inhibited cell migration, U251 cell migration was inhibited to 38.73±3.45% of control, LN229 cells to 57.40±2.16% of control and SNB19 cells to 34.17±3.82% of control. Also, CK666 significantly impaired Transwell chamber invasion capability of U251, LN229 and SNB19 cells compared with DMSO control by 72.70±4.86, 39.12±8.42 and 41.41±4.66%, respectively. The Arp2/3 complex is, therefore, likely to be a crucial participant in glioma cell invasion and migration, and may represent a target for therapeutic intervention.
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Affiliation(s)
- Zhifeng Liu
- Neuro-Oncology Laboratory, Tianjin Neurological Institute, Tianjin 300052, P.R. China
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39
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The regulation and functional impact of actin assembly at cadherin cell–cell adhesions. Semin Cell Dev Biol 2013; 24:298-307. [DOI: 10.1016/j.semcdb.2012.12.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 10/25/2012] [Accepted: 12/14/2012] [Indexed: 11/17/2022]
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Baggett AW, Cournia Z, Han MS, Patargias G, Glass AC, Liu SY, Nolen BJ. Structural characterization and computer-aided optimization of a small-molecule inhibitor of the Arp2/3 complex, a key regulator of the actin cytoskeleton. ChemMedChem 2012; 7:1286-94. [PMID: 22623398 PMCID: PMC3531959 DOI: 10.1002/cmdc.201200104] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 05/02/2012] [Indexed: 11/06/2022]
Abstract
CK-666 (1) is a recently discovered small-molecule inhibitor of the actin-related protein 2/3 (Arp2/3) complex, a key actin cytoskeleton regulator with roles in bacterial pathogenesis and cancer cell motility. Although 1 is commercially available, the crystal structure of Arp2/3 complex with 1 bound has not been reported, making its mechanism of action uncertain. Furthermore, its relatively low potency increases its potential for off-target effects in vivo, complicating interpretation of its influence in cell biological studies and precluding its clinical use. Herein we report the crystal structure of 1 bound to Arp2/3 complex, which reveals that 1 binds between the Arp2 and Arp3 subunits to stabilize the inactive conformation of the complex. Based on the crystal structure, we used computational docking and free-energy perturbation calculations of monosubstituted derivatives of 1 to guide optimization efforts. Biochemical assays of ten newly synthesized compounds led to the identification of compound 2, which exhibits a threefold increase in inhibitory activity in vitro relative to 1. In addition, our computational analyses unveiled a surface groove at the interface of the Arp2 and Arp3 subunits that can be exploited for additional structure-based optimization.
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Affiliation(s)
- Andrew W. Baggett
- Department of Chemistry, University of Oregon, Eugene, OR 97403-1253, United States Tel. 541-346-7412, Fax 541-346-5891
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 115 27 Athens, Greece
| | - Min Suk Han
- Department of Chemistry, University of Oregon, Eugene, OR 97403-1253, United States Tel. 541-346-7412, Fax 541-346-5891
| | - George Patargias
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 115 27 Athens, Greece
| | - Adam C. Glass
- Department of Chemistry, University of Oregon, Eugene, OR 97403-1253, United States Tel. 541-346-7412, Fax 541-346-5891
| | - Shih-Yuan Liu
- Department of Chemistry, University of Oregon, Eugene, OR 97403-1253, United States Tel. 541-346-7412, Fax 541-346-5891
| | - Brad J. Nolen
- Department of Chemistry, University of Oregon, Eugene, OR 97403-1253, United States Tel. 541-346-7412, Fax 541-346-5891
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Chisholm AD, Hsiao TI. The Caenorhabditis elegans epidermis as a model skin. I: development, patterning, and growth. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 1:861-78. [PMID: 23539299 DOI: 10.1002/wdev.79] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The skin of the nematode Caenorhabditis elegans is composed of a simple epidermal epithelium and overlying cuticle. The skin encloses the animal and plays central roles in body morphology and physiology; its simplicity and accessibility make it a tractable genetic model for several aspects of skin biology. Epidermal precursors are specified by a hierarchy of transcriptional regulators. Epidermal cells form on the dorsal surface of the embryo and differentiate to form the epidermal primordium, which then spreads out in a process of epiboly to enclose internal tissues. Subsequent elongation of the embryo into a vermiform larva is driven by cell shape changes and cell fusions in the epidermis. Most epidermal cells fuse in mid-embryogenesis to form a small number of multinucleate syncytia. During mid-embryogenesis the epidermis also becomes intimately associated with underlying muscles, performing a tendon-like role in transmitting muscle force. Post-embryonic development of the epidermis involves growth by addition of new cells to the syncytia from stem cell-like epidermal seam cells and by an increase in cell size driven by endoreplication of the chromosomes in epidermal nuclei.
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Affiliation(s)
- Andrew D Chisholm
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA.
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Synaptic polarity depends on phosphatidylinositol signaling regulated by myo-inositol monophosphatase in Caenorhabditis elegans. Genetics 2012; 191:509-21. [PMID: 22446320 PMCID: PMC3374314 DOI: 10.1534/genetics.111.137844] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Although neurons are highly polarized, how neuronal polarity is generated remains poorly understood. An evolutionarily conserved inositol-producing enzyme myo-inositol monophosphatase (IMPase) is essential for polarized localization of synaptic molecules in Caenorhabditis elegans and can be inhibited by lithium, a drug for bipolar disorder. The synaptic defect of IMPase mutants causes defects in sensory behaviors including thermotaxis. Here we show that the abnormalities of IMPase mutants can be suppressed by mutations in two enzymes, phospholipase Cβ or synaptojanin, which presumably reduce the level of membrane phosphatidylinositol 4,5-bisphosphate (PIP2). We also found that mutations in phospholipase Cβ conferred resistance to lithium treatment. Our results suggest that reduction of PIP2 on plasma membrane is a major cause of abnormal synaptic polarity in IMPase mutants and provide the first in vivo evidence that lithium impairs neuronal PIP2 synthesis through inhibition of IMPase. We propose that the PIP2 signaling regulated by IMPase plays a novel and fundamental role in the synaptic polarity.
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43
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Mohamed AM, Boudreau JR, Yu FPS, Liu J, Chin-Sang ID. The Caenorhabditis elegans Eph receptor activates NCK and N-WASP, and inhibits Ena/VASP to regulate growth cone dynamics during axon guidance. PLoS Genet 2012; 8:e1002513. [PMID: 22383893 PMCID: PMC3285579 DOI: 10.1371/journal.pgen.1002513] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 12/13/2011] [Indexed: 01/18/2023] Open
Abstract
The Eph receptor tyrosine kinases (RTKs) are regulators of cell migration and axon guidance. However, our understanding of the molecular mechanisms by which Eph RTKs regulate these processes is still incomplete. To understand how Eph receptors regulate axon guidance in Caenorhabditis elegans, we screened for suppressors of axon guidance defects caused by a hyperactive VAB-1/Eph RTK. We identified NCK-1 and WSP-1/N-WASP as downstream effectors of VAB-1. Furthermore, VAB-1, NCK-1, and WSP-1 can form a complex in vitro. We also report that NCK-1 can physically bind UNC-34/Enabled (Ena), and suggest that VAB-1 inhibits the NCK-1/UNC-34 complex and negatively regulates UNC-34. Our results provide a model of the molecular events that allow the VAB-1 RTK to regulate actin dynamics for axon guidance. We suggest that VAB-1/Eph RTK can stop axonal outgrowth by inhibiting filopodia formation at the growth cone by activating Arp2/3 through a VAB-1/NCK-1/WSP-1 complex and by inhibiting UNC-34/Ena activity. The correct wiring of the nervous system depends on the ability of axons to properly interpret extracellular cues that guide them to their targets. The Eph receptor tyrosine kinases (RTKs) have roles in guiding axons, but their signaling pathways are not completely understood. In this study, we used the nematode Caenorhabditis elegans to study how the VAB-1 Eph RTK regulates the growth cone structure for axon guidance. Genetic and molecular data show that VAB-1 regulates the conserved molecules NCK-1, WSP-1/N-WASP, and UNC-34/Ena. Our study provides a model of how the VAB-1 Eph RTK modulates the growth cone structure to inhibit axonal outgrowth. We show that activated VAB-1 can inhibit an NCK-1/UNC-34 interaction by binding to the NCK-1 SH2 domain. We also show that NCK-1 and WSP-1 can physically interact and that VAB-1/NCK-1 and WSP-1 form a complex in vitro. We suggest that the VAB-1 Eph RTK can contribute to the termination of axon outgrowth by two methods: 1) The VAB-1/NCK-1/WSP-1 complex activates ARP-2/3 to change the actin growth cone dynamics to that of a branched structure thus reducing the number of filopodia, and 2) VAB-1 inhibits axon extension by inhibiting UNC-34/Ena's function in actin polymerization.
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Affiliation(s)
| | | | | | - Jun Liu
- Department of Biology, Queen's University, Kingston, Canada
| | - Ian D. Chin-Sang
- Department of Biology, Queen's University, Kingston, Canada
- * E-mail:
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Loss of cofilin 1 disturbs actin dynamics, adhesion between enveloping and deep cell layers and cell movements during gastrulation in zebrafish. PLoS One 2010; 5:e15331. [PMID: 21203473 PMCID: PMC3008747 DOI: 10.1371/journal.pone.0015331] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 11/06/2010] [Indexed: 12/25/2022] Open
Abstract
During gastrulation, cohesive migration drives associated cell layers to the completion of epiboly in zebrafish. The association of different layers relies on E-cadherin based cellular junctions, whose stability can be affected by actin turnover. Here, we examined the effect of malfunctioning actin turnover on the epibolic movement by knocking down an actin depolymerizing factor, cofilin 1, using antisense morpholino oligos (MO). Knockdown of cfl1 interfered with epibolic movement of deep cell layer (DEL) but not in the enveloping layer (EVL) and the defect could be specifically rescued by overexpression of cfl1. It appeared that the uncoordinated movements of DEL and EVL were regulated by the differential expression of cfl1 in the DEL, but not EVL as shown by in situ hybridization. The dissociation of DEL and EVL was further evident by the loss of adhesion between layers by using transmission electronic and confocal microscopy analyses. cfl1 morphants also exhibited abnormal convergent extension, cellular migration and actin filaments, but not involution of hypoblast. The cfl1 MO-induced cell migration defect was found to be cell-autonomous in cell transplantation assays. These results suggest that proper actin turnover mediated by Cfl1 is essential for adhesion between DEL and EVL and cell movements during gastrulation in zebrafish.
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Eriksson T, Varshney G, Aspenström P, Palmer RH. Characterisation of the role of Vrp1 in cell fusion during the development of visceral muscle of Drosophila melanogaster. BMC DEVELOPMENTAL BIOLOGY 2010; 10:86. [PMID: 20701765 PMCID: PMC2931478 DOI: 10.1186/1471-213x-10-86] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 08/11/2010] [Indexed: 12/03/2022]
Abstract
Background In Drosophila muscle cell fusion takes place both during the formation of the somatic mesoderm and the visceral mesoderm, giving rise to the skeletal muscles and the gut musculature respectively. The core process of myoblast fusion is believed to be similar for both organs. The actin cytoskeleton regulator Verprolin acts by binding to WASP, which in turn binds to the Arp2/3 complex and thus activates actin polymerization. While Verprolin has been shown to be important for somatic muscle cell fusion, the function of this protein in visceral muscle fusion has not been determined. Results Verprolin is specifically expressed in the fusion competent myoblasts of the visceral mesoderm, suggesting a role in visceral mesoderm fusion. We here describe a novel Verprolin mutant allele which displays subtle visceral mesoderm fusion defects in the form of mislocalization of the immunoglobulin superfamily molecule Duf/Kirre, which is required on the myoblast cell surface to facilitate attachment between cells that are about to fuse, indicating a function for Verprolin in visceral mesoderm fusion. We further show that Verprolin mutant cells are capable of both migrating and fusing and that the WASP-binding domain of Verprolin is required for rescue of the Verprolin mutant phenotype. Conclusions Verprolin is expressed in the visceral mesoderm and plays a role in visceral muscle fusion as shown by mislocalization of Duf/Kirre in the Verprolin mutant, however it is not absolutely required for myoblast fusion in either the visceral or the somatic mesoderm.
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Affiliation(s)
- Therese Eriksson
- Department of Molecular Biology, Building 6L, Umeå University, Umeå S-90187, Sweden
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Roh-Johnson M, Goldstein B. In vivo roles for Arp2/3 in cortical actin organization during C. elegans gastrulation. J Cell Sci 2010; 122:3983-93. [PMID: 19889970 DOI: 10.1242/jcs.057562] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The Arp2/3 complex is important for morphogenesis in various developmental systems, but specific in vivo roles for this complex in cells that move during morphogenesis are not well understood. We have examined cellular roles for Arp2/3 in the Caenorhabditis elegans embryo. In C. elegans, the first morphogenetic movement, gastrulation, is initiated by the internalization of two endodermal precursor cells. These cells undergo a myosin-dependent apical constriction, pulling a ring of six neighboring cells into a gap left behind on the ventral surface of the embryo. In agreement with a previous report, we found that in Arp2/3-depleted C. elegans embryos, membrane blebs form and the endodermal precursor cells fail to fully internalize. We show that these cells are normal with respect to several key requirements for gastrulation: cell cycle timing, cell fate, apicobasal cell polarity and apical accumulation and activation of myosin-II. To further understand the function of Arp2/3 in gastrulation, we examined F-actin dynamics in wild-type embryos. We found that three of the six neighboring cells extend short, dynamic F-actin-rich processes at their apical borders with the internalizing cells. These processes failed to form in embryos that were depleted of Arp2/3 or the apical protein PAR-3. Our results identify an in vivo role for Arp2/3 in the formation of subcellular structures during morphogenesis. The results also suggest a new layer to the model of C. elegans gastrulation: in addition to apical constriction, internalization of the endoderm might involve dynamic Arp2/3-dependent F-actin-rich extensions on one side of a ring of cells.
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Affiliation(s)
- Minna Roh-Johnson
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Epp E, Walther A, Lépine G, Leon Z, Mullick A, Raymond M, Wendland J, Whiteway M. Forward genetics in Candida albicans that reveals the Arp2/3 complex is required for hyphal formation, but not endocytosis. Mol Microbiol 2010; 75:1182-98. [PMID: 20141603 DOI: 10.1111/j.1365-2958.2009.07038.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Candida albicans is a diploid fungal pathogen lacking a defined complete sexual cycle, and thus has been refractory to standard forward genetic analysis. Instead, transcription profiling and reverse genetic strategies based on Saccharomyces cerevisiae have typically been used to link genes to functions. To overcome restrictions inherent in such indirect approaches, we have investigated a forward genetic mutagenesis strategy based on the UAU1 technology. We screened 4700 random insertion mutants for defects in hyphal development and linked two new genes (ARP2 and VPS52) to hyphal growth. Deleting ARP2 abolished hyphal formation, generated round and swollen yeast phase cells, disrupted cortical actin patches and blocked virulence in mice. The mutants also showed a global lack of induction of hyphae-specific genes upon the yeast-to-hyphae switch. Surprisingly, both arp2 Delta/Delta and arp2 Delta/Delta arp3 Delta/Delta mutants were still able to endocytose FM4-64 and Lucifer Yellow, although as shown by time-lapse movies internalization of FM4-64 was somewhat delayed in mutant cells. Thus the non-essential role of the Arp2/3 complex discovered by forward genetic screening in C. albicans showed that uptake of membrane components from the plasma membrane to vacuolar structures is not dependent on this actin nucleating machinery.
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Affiliation(s)
- Elias Epp
- Biotechnology Research Institute, National Research Council of Canada, Montréal, QC H4P 2R2, Canada
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Pellegrino MW, Gasser RB, Sprenger F, Stetak A, Hajnal A. The conserved zinc finger protein VAB-23 is an essential regulator of epidermal morphogenesis in Caenorhabditis elegans. Dev Biol 2009; 336:84-93. [DOI: 10.1016/j.ydbio.2009.09.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 09/17/2009] [Accepted: 09/23/2009] [Indexed: 01/29/2023]
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