1
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Prins R, Windsor P, Miller BR, Maiden S. Alleles of unc-33/CRMP exhibit defects during Caenorhabditis elegans epidermal morphogenesis. Dev Dyn 2022; 251:1741-1753. [PMID: 35538612 DOI: 10.1002/dvdy.497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/16/2022] [Accepted: 04/27/2022] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND Microtubule-associated proteins regulate the dynamics, organization, and function of microtubules, impacting a number of vital cellular processes. CRMPs have been shown to control microtubule assembly and axon outgrowth during neuronal differentiation. While many microtubule-associated proteins have been linked to roles in cell division and neuronal development, it is still unclear the complement that control the formation of parallel microtubule arrays in epithelial cells. RESULTS Here we show through time-lapse DIC microscopy that Caenorhabditis elegans embryos homozygous for the weak loss-of-function allele unc-33(e204) progress more slowly through epidermal morphogenesis, while animals homozygous for strong loss-of-function alleles exhibit more embryonic lethality. Identification of two novel missense mutations in unc-33(e572), Val476Gly and Ser731Thr, lead to computational approaches to determine the potential effects of these changes on UNC-33/CRMP structure. Molecular dynamics simulations show that for Asp389Asn and Arg502His, two other known missense mutations, local changes in protein-protein hydrogen bonding affect the stability of the protein. However, the Val476Gly/Ser731Thr combination does not alter the structure or energetics of UNC-33 drastically when compared to the wild-type protein. CONCLUSIONS These results support a novel role for UNC-33/CRMP in C. elegans epidermal development and shed light on how individual amino acid changes cause a loss-of-function in UNC-33. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Rachel Prins
- Department of Biology, Truman State University, Kirksville, MO
| | - Peter Windsor
- Department of Chemistry, Truman State University, Kirksville, MO
| | - Bill R Miller
- Department of Chemistry, Truman State University, Kirksville, MO
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2
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CDK14 Promotes Axon Regeneration by Regulating the Noncanonical Wnt Signaling Pathway in a Kinase-Independent Manner. J Neurosci 2021; 41:8309-8320. [PMID: 34429379 PMCID: PMC8496196 DOI: 10.1523/jneurosci.0711-21.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 08/05/2021] [Accepted: 08/10/2021] [Indexed: 01/13/2023] Open
Abstract
The postinjury regenerative capacity of neurons is known to be mediated by a complex interaction of intrinsic regenerative pathways and external cues. In Caenorhabditis elegans, the initiation of axon regeneration is regulated by the nonmuscle myosin light chain-4 (MLC-4) phosphorylation signaling pathway. In this study, we have identified svh-16/cdk-14, a mammalian CDK14 homolog, as a positive regulator of axon regeneration in motor neurons. We then isolated the CDK-14-binding protein MIG-5/Disheveled (Dsh) and found that EGL-20/Wnt and the MIG-1/Frizzled receptor (Fz) are required for efficient axon regeneration. Further, we demonstrate that CDK-14 activates EPHX-1, the C. elegans homolog of the mammalian ephexin Rho-type GTPase guanine nucleotide exchange factor (GEF), in a kinase-independent manner. EPHX-1 functions as a GEF for the CDC-42 GTPase, inhibiting myosin phosphatase, which maintains MLC-4 phosphorylation. These results suggest that CDK14 activates the RhoGEF–CDC42–MLC phosphorylation axis in a noncanonical Wnt signaling pathway that promotes axon regeneration. SIGNIFICANCE STATEMENT Noncanonical Wnt signaling is mediated by Frizzled receptor (Fz), Disheveled (Dsh), Rho-type GTPase, and nonmuscle myosin light chain (MLC) phosphorylation. This study identified svh-16/cdk-14, which encodes a mammalian CDK14 homolog, as a regulator of axon regeneration in Caenorhabditis elegans motor neurons. We show that CDK-14 binds to MIG-5/Dsh, and that EGL-20/Wnt, MIG-1/Fz, and EPHX-1/RhoGEF are required for axon regeneration. The phosphorylation-mimetic MLC-4 suppressed axon regeneration defects in mig-1, cdk-14, and ephx-1 mutants. CDK-14 mediates kinase-independent activation of EPHX-1, which functions as a guanine nucleotide exchange factor for CDC-42 GTPase. Activated CDC-42 inactivates myosin phosphatase and thereby maintains MLC phosphorylation. Thus, the noncanonical Wnt signaling pathway controls axon regeneration via the CDK-14–EPHX-1–CDC-42–MLC phosphorylation axis.
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Drewnik ED, Wiesenfahrt T, Smit RB, Park YJ, Pallotto LM, Mains PE. Tissue-specific regulation of epidermal contraction during C. elegans embryonic morphogenesis. G3-GENES GENOMES GENETICS 2021; 11:6273666. [PMID: 33974063 PMCID: PMC8495928 DOI: 10.1093/g3journal/jkab164] [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] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 05/05/2021] [Indexed: 11/17/2022]
Abstract
Actin and myosin mediate the epidermal cell contractions that elongate the Caenorhabditis elegans embryo from an ovoid to a tubular-shaped worm. Contraction occurs mainly in the lateral epidermal cells, while the dorsoventral epidermis plays a more passive role. Two parallel pathways trigger actinomyosin contraction, one mediated by LET-502/Rho kinase and the other by PAK-1/p21 activated kinase. A number of genes mediating morphogenesis have been shown to be sufficient when expressed either laterally or dorsoventrally. Additional genes show either lateral or dorsoventral phenotypes. This led us to a model where contractile genes have discrete functions in one or the other cell type. We tested this by examining several genes for either lateral or dorsoventral sufficiency. LET-502 expression in the lateral cells was sufficient to drive elongation. MEL-11/Myosin phosphatase, which antagonizes contraction, and PAK-1 were expected to function dorsoventrally, but we could not detect tissue-specific sufficiency. Double mutants of lethal alleles predicted to decrease lateral contraction with those thought to increase dorsoventral force were previously shown to be viable. We hypothesized that these mutant combinations shifted the contractile force from the lateral to the dorsoventral cells and so the embryos would elongate with less lateral cell contraction. This was tested by examining 10 single and double mutant strains. In most cases, elongation proceeded without a noticeable alteration in lateral contraction. We suggest that many embryonic elongation genes likely act in both lateral and dorsoventral cells, even though they may have their primary focus in one or the other cell type.
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Affiliation(s)
- Elizabeth D Drewnik
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Tobias Wiesenfahrt
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Ryan B Smit
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Ye-Jean Park
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Linda M Pallotto
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Paul E Mains
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
- Corresponding author: Department of Biochemistry and Molecular Biology, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB T2N 4N1, Canada.
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4
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Jud MC, Lowry J, Padilla T, Clifford E, Yang Y, Fennell F, Miller AK, Hamill D, Harvey AM, Avila-Zavala M, Shao H, Nguyen Tran N, Bao Z, Bowerman B. A genetic screen for temperature-sensitive morphogenesis-defective Caenorhabditis elegans mutants. G3-GENES GENOMES GENETICS 2021; 11:6169531. [PMID: 33713117 PMCID: PMC8133775 DOI: 10.1093/g3journal/jkab026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 01/18/2021] [Indexed: 11/21/2022]
Abstract
Morphogenesis involves coordinated cell migrations and cell shape changes that generate tissues and organs, and organize the body plan. Cell adhesion and the cytoskeleton are important for executing morphogenesis, but their regulation remains poorly understood. As genes required for embryonic morphogenesis may have earlier roles in development, temperature-sensitive embryonic-lethal mutations are useful tools for investigating this process. From a collection of ∼200 such Caenorhabditis elegans mutants, we have identified 17 that have highly penetrant embryonic morphogenesis defects after upshifts from the permissive to the restrictive temperature, just prior to the cell shape changes that mediate elongation of the ovoid embryo into a vermiform larva. Using whole genome sequencing, we identified the causal mutations in seven affected genes. These include three genes that have roles in producing the extracellular matrix, which is known to affect the morphogenesis of epithelial tissues in multicellular organisms: the rib-1 and rib-2 genes encode glycosyltransferases, and the emb-9 gene encodes a collagen subunit. We also used live imaging to characterize epidermal cell shape dynamics in one mutant, or1219ts, and observed cell elongation defects during dorsal intercalation and ventral enclosure that may be responsible for the body elongation defects. These results indicate that our screen has identified factors that influence morphogenesis and provides a platform for advancing our understanding of this fundamental biological process.
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Affiliation(s)
- Molly C Jud
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
| | - Josh Lowry
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
| | - Thalia Padilla
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
| | - Erin Clifford
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
| | - Yuqi Yang
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
| | - Francesca Fennell
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
| | - Alexander K Miller
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
| | - Danielle Hamill
- Department of Zoology, Ohio Wesleyan University, Delaware, OH, 43015, USA
| | - Austin M Harvey
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
| | - Martha Avila-Zavala
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
| | - Hong Shao
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, 10065, USA
| | - Nhan Nguyen Tran
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, 10065, USA
| | - Zhirong Bao
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, 10065, USA
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, OR, 97402, USA
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Garzanelli J, Maiden S. Exposing a novel genetic interaction between unc-33/CRMP and hmp-2/β-catenin during Caenorhabditis elegans embryogenesis. MICROPUBLICATION BIOLOGY 2020; 2020:10.17912/micropub.biology.000286. [PMID: 32760883 PMCID: PMC7396159 DOI: 10.17912/micropub.biology.000286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- John Garzanelli
- Biology Department, Truman State University, Kirksville, MO, 63501
| | - Stephanie Maiden
- Biology Department, Truman State University, Kirksville, MO, 63501,
Correspondence to: Stephanie Maiden ()
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6
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Kelley CA, De Henau S, Bell L, Dansen TB, Cram EJ. Redox signaling modulates Rho activity and tissue contractility in the Caenorhabditis elegans spermatheca. Mol Biol Cell 2020; 31:1486-1497. [PMID: 32374641 PMCID: PMC7359568 DOI: 10.1091/mbc.e20-04-0236] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Actomyosin-based contractility in smooth muscle and nonmuscle cells is regulated by signaling through the small GTPase Rho and by calcium-activated pathways. We use the myoepithelial cells of the Caenorhabditis elegans spermatheca to study the mechanisms of coordinated myosin activation in vivo. Here, we show that redox signaling modulates RHO-1/Rho activity in this contractile tissue. Exogenously added as well as endogenously generated hydrogen peroxide decreases spermathecal contractility by inhibition of RHO-1, which depends on a conserved cysteine in its nucleotide binding site (C20). Further, we identify an endogenous gradient of H2O2 across the spermathecal tissue, which depends on the activity of cytosolic superoxide dismutase, SOD-1. Collectively, we show that SOD-1-mediated H2O2 production regulates the redox environment and fine tunes Rho activity across the spermatheca through oxidation of RHO-1 C20.
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Affiliation(s)
| | - Sasha De Henau
- Center for Molecular Medicine, Molecular Cancer Research Section, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Liam Bell
- Department of Biology, Northeastern University, Boston, MA 02115
| | - Tobias B Dansen
- Center for Molecular Medicine, Molecular Cancer Research Section, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
| | - Erin J Cram
- Department of Biology, Northeastern University, Boston, MA 02115
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Suresh A, Wightman B. The daf-2 insulin receptor functions in C. elegans embryo elongation. MICROPUBLICATION BIOLOGY 2020; 2020:10.17912/micropub.biology.000117. [PMID: 32550500 PMCID: PMC7252343 DOI: 10.17912/micropub.biology.000117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Annu Suresh
- Biology Department, Muhlenberg College, 2400 Chew St., Allentown, PA 18104 USA
| | - Bruce Wightman
- Biology Department, Muhlenberg College, 2400 Chew St., Allentown, PA 18104 USA,
Correspondence to: Bruce Wightman ()
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8
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Wallace AG, Raduwan H, Carlet J, Soto MC. The RhoGAP HUM-7/Myo9 integrates signals to modulate RHO-1/RhoA during embryonic morphogenesis in Caenorhabditiselegans. Development 2018; 145:dev168724. [PMID: 30389847 PMCID: PMC6288380 DOI: 10.1242/dev.168724] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/29/2018] [Indexed: 01/23/2023]
Abstract
During embryonic morphogenesis, cells and tissues undergo dramatic movements under the control of F-actin regulators. Our studies of epidermal cell migrations in developing Caenorhabditiselegans embryos have identified multiple plasma membrane signals that regulate the Rac GTPase, thus regulating WAVE and Arp2/3 complexes, to promote branched F-actin formation and polarized enrichment. Here, we describe a pathway that acts in parallel to Rac to transduce membrane signals to control epidermal F-actin through the GTPase RHO-1/RhoA. RHO-1 contributes to epidermal migration through effects on underlying neuroblasts. We identify signals to regulate RHO-1-dependent events in the epidermis. HUM-7, the C. elegans homolog of human MYO9A and MYO9B, regulates F-actin dynamics during epidermal migration. Genetics and biochemistry support that HUM-7 behaves as a GTPase-activating protein (GAP) for the RHO-1/RhoA and CDC-42 GTPases. Loss of HUM-7 enhances RHO-1-dependent epidermal cell behaviors. We identify SAX-3/ROBO as an upstream signal that contributes to attenuated RHO-1 activation through its regulation of HUM-7/Myo9. These studies identify a new role for RHO-1 during epidermal cell migration, and suggest that RHO-1 activity is regulated by SAX-3/ROBO acting on the RhoGAP HUM-7.
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Affiliation(s)
- Andre G Wallace
- Department of Pathology and Laboratory Medicine, Rutgers - Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
- School of Natural Sciences, Fairleigh Dickinson University, Teaneck, NJ 07666, USA
| | - Hamidah Raduwan
- Department of Pathology and Laboratory Medicine, Rutgers - Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - John Carlet
- School of Natural Sciences, Fairleigh Dickinson University, Teaneck, NJ 07666, USA
| | - Martha C Soto
- Department of Pathology and Laboratory Medicine, Rutgers - Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
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9
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Markwardt ML, Snell NE, Guo M, Wu Y, Christensen R, Liu H, Shroff H, Rizzo MA. A Genetically Encoded Biosensor Strategy for Quantifying Non-muscle Myosin II Phosphorylation Dynamics in Living Cells and Organisms. Cell Rep 2018; 24:1060-1070.e4. [PMID: 30044973 PMCID: PMC6117825 DOI: 10.1016/j.celrep.2018.06.088] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 05/25/2018] [Accepted: 06/20/2018] [Indexed: 02/06/2023] Open
Abstract
Complex cell behaviors require dynamic control over non-muscle myosin II (NMMII) regulatory light chain (RLC) phosphorylation. Here, we report that RLC phosphorylation can be tracked in living cells and organisms using a homotransfer fluorescence resonance energy transfer (FRET) approach. Fluorescent protein-tagged RLCs exhibit FRET in the dephosphorylated conformation, permitting identification and quantification of RLC phosphorylation in living cells. This approach is versatile and can accommodate several different fluorescent protein colors, thus enabling multiplexed imaging with complementary biosensors. In fibroblasts, dynamic myosin phosphorylation was observed at the leading edge of migrating cells and retracting structures where it persistently colocalized with activated myosin light chain kinase. Changes in myosin phosphorylation during C. elegans embryonic development were tracked using polarization inverted selective-plane illumination microscopy (piSPIM), revealing a shift in phosphorylated myosin localization to a longitudinal orientation following the onset of twitching. Quantitative analyses further suggested that RLC phosphorylation dynamics occur independently from changes in protein expression.
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Affiliation(s)
- Michele L Markwardt
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Nicole E Snell
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Min Guo
- Section on High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, US NIH, Bethesda, MD 20814, USA
| | - Yicong Wu
- Section on High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, US NIH, Bethesda, MD 20814, USA
| | - Ryan Christensen
- Section on High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, US NIH, Bethesda, MD 20814, USA
| | - Huafeng Liu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Hari Shroff
- Section on High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, US NIH, Bethesda, MD 20814, USA
| | - M A Rizzo
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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10
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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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11
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Kelley CA, Wirshing ACE, Zaidel-Bar R, Cram EJ. The myosin light-chain kinase MLCK-1 relocalizes during Caenorhabditis elegans ovulation to promote actomyosin bundle assembly and drive contraction. Mol Biol Cell 2018; 29:1975-1991. [PMID: 30088798 PMCID: PMC6232974 DOI: 10.1091/mbc.e18-01-0056] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
We identify the Caenorhabditis elegans myosin light-chain kinase, MLCK-1, required for contraction of spermathecae. During contraction, MLCK-1 moves from the apical cell boundaries to the basal actomyosin bundles, where it stabilizes myosin downstream of calcium signaling. MLCK and ROCK act in distinct subsets of cells to coordinate the timing of contraction.
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Affiliation(s)
| | | | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Erin J Cram
- Department of Biology, Northeastern University, Boston, MA 02115
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12
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Martin E, Bonnamour G, Jenna S. AMPK and autophagy control embryonic elongation as part of a RhoA-like morphogenic program in nematode. Small GTPases 2017; 11:186-193. [PMID: 29172954 DOI: 10.1080/21541248.2017.1372868] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Autophagy is the process where cytosolic components are digested by the cell. This process is required for cell survival in stressful conditions. It was also shown to control cell division and more recently, cell morphology and migration. We characterized signalling pathways enabling embryonic epidermal cells of the nematode Caenorhabditis elegans to elongate along their antero-posterior axis. Previous studies revealed that epidermal cells can adopt either a RhoA-like or a Rac1-like morphogenic program. We show here that the AMP-activated protein kinase (AMPK) and genes controlling autophagy are required for proper elongation of epidermal cells following the RhoA-like program and are dispensable for other cells. This suggests that AMPK-autophagy is used by the embryo to fuel the most energy-demanding morphogenic processes promoting early elongation.
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Affiliation(s)
- Emmanuel Martin
- Integrative Genomics and cell signaling laboratory, Chemistry-Biochemistry Department, Université du Québec à Montréal (UQAM), Montreal, Canada
| | - Grégoire Bonnamour
- Integrative Genomics and cell signaling laboratory, Chemistry-Biochemistry Department, Université du Québec à Montréal (UQAM), Montreal, Canada
| | - Sarah Jenna
- Integrative Genomics and cell signaling laboratory, Chemistry-Biochemistry Department, Université du Québec à Montréal (UQAM), Montreal, Canada
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13
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Praslicka B, Harmson JS, Kim J, Rangaraj VR, Ooi A, Gissendanner CR. BINDING SITE ANALYSIS OF THE CAENORHABDITIS ELEGANS NR4A NUCLEAR RECEPTOR NHR-6 DURING DEVELOPMENT. NUCLEAR RECEPTOR RESEARCH 2017; 4. [PMID: 29026837 DOI: 10.11131/2017/101288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Members of the NR4A subfamily of nuclear receptors make up a highly conserved, functionally diverse group of transcription factors implicated in a multitude of cellular processes such as proliferation, differentiation, apoptosis, metabolism and DNA repair. The gene nhr-6, which encodes the sole C. elegans NR4A nuclear receptor homolog, has a critical role in organogenesis and regulates the development of the spermatheca organ system. Our previous work revealed that nhr-6 is required for spermatheca cell divisions in late L3 and early L4 and spermatheca cell differentiation during the mid L4 stage. Here, we utilized chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) to identify NHR-6 binding sites during both the late L3/early L4 and mid L4 developmental stages. Our results revealed 30,745 enriched binding sites for NHR-6, ~70% of which were within 3 kb upstream of a gene transcription start site. Binding sites for a cohort of candidate target genes with probable functions in spermatheca organogenesis were validated through qPCR. Reproductive and spermatheca phenotypes were also evaluated for these genes following a loss-of-function RNAi screen which revealed several genes with critical functions during spermatheca organogenesis. Our results uncovered a complex nuclear receptor regulatory network whereby NHR-6 regulates multiple cellular processes during spermatheca organogenesis.
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Affiliation(s)
- Brandon Praslicka
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, and Biology Program, School of Science, University of Louisiana Monroe, Monroe, LA, USA 71209
| | - Jeremy S Harmson
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, and Biology Program, School of Science, University of Louisiana Monroe, Monroe, LA, USA 71209
| | - Joohyun Kim
- Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, USA 70803
| | - Vittobai Rashika Rangaraj
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, and Biology Program, School of Science, University of Louisiana Monroe, Monroe, LA, USA 71209
| | - Aikseng Ooi
- Department of Pharmacology & Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, USA 85721
| | - Chris R Gissendanner
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, and Biology Program, School of Science, University of Louisiana Monroe, Monroe, LA, USA 71209
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14
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Martin E, Ouellette MH, Jenna S. Rac1/RhoA antagonism defines cell-to-cell heterogeneity during epidermal morphogenesis in nematodes. J Cell Biol 2016; 215:483-498. [PMID: 27821782 PMCID: PMC5119937 DOI: 10.1083/jcb.201604015] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 07/29/2016] [Accepted: 10/19/2016] [Indexed: 01/13/2023] Open
Abstract
Antagonism between the GTPases Rac1 and RhoA controls different morphogenetic processes during embryonic development. Martin et al. use quantitative imaging analyses to demonstrate that cell-autonomous antagonism between the RhoA- and Rac1-like pathways defines cell-to-cell heterogeneity during epidermal morphogenesis in Caenorhabditis elegans. The antagonism between the GTPases Rac1 and RhoA controls cell-to-cell heterogeneity in isogenic populations of cells in vitro and epithelial morphogenesis in vivo. Its involvement in the regulation of cell-to-cell heterogeneity during epidermal morphogenesis has, however, never been addressed. We used a quantitative cell imaging approach to characterize epidermal morphogenesis at a single-cell level during early elongation of Caenorhabditis elegans embryos. This study reveals that a Rac1-like pathway, involving the Rac/Cdc42 guanine-exchange factor β-PIX/PIX-1 and effector PAK1/PAK-1, and a RhoA-like pathway, involving ROCK/LET-502, control the remodeling of apical junctions and the formation of basolateral protrusions in distinct subsets of hypodermal cells. In these contexts, protrusions adopt lamellipodia or an amoeboid morphology. We propose that lamella formation may reduce tension building at cell–cell junctions during morphogenesis. Cell-autonomous antagonism between these pathways enables cells to switch between Rac1- and RhoA-like morphogenetic programs. This study identifies the first case of cell-to-cell heterogeneity controlled by Rac1/RhoA antagonism during epidermal morphogenesis.
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Affiliation(s)
- Emmanuel Martin
- Department of Chemistry, Pharmaqam, Université du Québec à Montréal, Montreal, QC H3C 3P8, Canada
| | - Marie-Hélène Ouellette
- Department of Chemistry, Pharmaqam, Université du Québec à Montréal, Montreal, QC H3C 3P8, Canada
| | - Sarah Jenna
- Department of Chemistry, Pharmaqam, Université du Québec à Montréal, Montreal, QC H3C 3P8, Canada
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Martin E, Rocheleau-Leclair O, Jenna S. Novel Metrics to Characterize Embryonic Elongation of the Nematode Caenorhabditis elegans. J Vis Exp 2016:e53712. [PMID: 27077374 DOI: 10.3791/53712] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Dissecting the signaling pathways that control the alteration of morphogenic processes during embryonic development requires robust and sensitive metrics. Embryonic elongation of the nematode Caenorhabditis elegans is a late developmental stage consisting of the elongation of the embryo along its longitudinal axis. This developmental stage is controlled by intercellular communication between hypodermal cells and underlying body-wall muscles. These signaling mechanisms control the morphology of hypodermal cells by remodeling the cytoskeleton and the cell-cell junctions. Measurement of embryonic lethality and developmental arrest at larval stages as well as alteration of cytoskeleton and cell-cell adhesion structures in hypodermal and muscle cells are classical phenotypes that have been used for more than 25 years to dissect these signaling pathways. Recent studies required the development of novel metrics specifically targeting either early or late elongation and characterizing morphogenic defects along the antero-posterior axis of the embryo. Here, we provide detailed protocols enabling the accurate measurement of the length and the width of the elongating embryos as well as the length of synchronized larvae. These methods constitute useful tools to identify genes controlling elongation, to assess whether these genes control both early and late phases of this stage and are required evenly along the antero-posterior axis of the embryo.
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Affiliation(s)
- Emmanuel Martin
- Department of Chemistry, Pharmaqam, Université du Québec à Montréal
| | | | - Sarah Jenna
- Department of Chemistry, Pharmaqam, Université du Québec à Montréal;
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Wernike D, Chen Y, Mastronardi K, Makil N, Piekny A. Mechanical forces drive neuroblast morphogenesis and are required for epidermal closure. Dev Biol 2016; 412:261-77. [PMID: 26923492 DOI: 10.1016/j.ydbio.2016.02.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 02/24/2016] [Accepted: 02/24/2016] [Indexed: 10/22/2022]
Abstract
Tissue morphogenesis requires myosin-dependent events such as cell shape changes and migration to be coordinated between cells within a tissue, and/or with cells from other tissues. However, few studies have investigated the simultaneous morphogenesis of multiple tissues in vivo. We found that during Caenorhabditis elegans ventral enclosure, when epidermal cells collectively migrate to cover the ventral surface of the embryo, the underlying neuroblasts (neuronal precursor cells) also undergo morphogenesis. We found that myosin accumulates as foci along the junction-free edges of the ventral epidermal cells to form a ring, whose closure is myosin-dependent. We also observed the accumulation of myosin foci and the adhesion junction proteins E-cadherin and α-catenin in the underlying neuroblasts. Myosin may help to reorganize a subset of neuroblasts into a rosette-like pattern, and decrease their surface area as the overlying epidermal cells constrict. Since myosin is required in the neuroblasts for ventral enclosure, we propose that mechanical forces in the neuroblasts influence constriction of the overlying epidermal cells. In support of this model, disrupting neuroblast cell division or altering their fate influences myosin localization in the overlying epidermal cells. The coordination of myosin-dependent events and forces between cells in different tissues could be a common theme for coordinating morphogenetic events during metazoan development.
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Affiliation(s)
- Denise Wernike
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Yun Chen
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | | | - Neetha Makil
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, Quebec, Canada.
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Ono K, Ono S. Two distinct myosin II populations coordinate ovulatory contraction of the myoepithelial sheath in the Caenorhabditis elegans somatic gonad. Mol Biol Cell 2016; 27:1131-42. [PMID: 26864628 PMCID: PMC4814220 DOI: 10.1091/mbc.e15-09-0648] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 02/05/2016] [Indexed: 01/13/2023] Open
Abstract
In the nematode somatic gonad, nonmuscle myosin and muscle myosin form distinct filaments and coordinate ovulatory contraction of the myoepithelial sheath. Nonmuscle myosin regulatory light chain is phosphoregulated, and its phosphorylation and dephosphorylation are critical for successful ovulation. The myoepithelial sheath in the somatic gonad of the nematode Caenorhabditis elegans has nonstriated contractile actomyosin networks that produce highly coordinated contractility for ovulation of mature oocytes. Two myosin heavy chains are expressed in the myoepithelial sheath, which are also expressed in the body-wall striated muscle. The troponin/tropomyosin system is also present and essential for ovulation. Therefore, although the myoepithelial sheath has smooth muscle–like contractile apparatuses, it has a striated muscle–like regulatory mechanism through troponin/tropomyosin. Here we report that the myoepithelial sheath has a distinct myosin population containing nonmuscle myosin II isoforms, which is regulated by phosphorylation and essential for ovulation. MLC-4, a nonmuscle myosin regulatory light chain, localizes to small punctate structures and does not colocalize with large, needle-like myosin filaments containing MYO-3, a striated-muscle myosin isoform. RNA interference of MLC-4, as well as of its upstream regulators, LET-502 (Rho-associated coiled-coil forming kinase) and MEL-11 (a myosin-binding subunit of myosin phosphatase), impairs ovulation. Expression of a phosphomimetic MLC-4 mutant mimicking a constitutively active state also impairs ovulation. A striated-muscle myosin (UNC-54) appears to provide partially compensatory contractility. Thus the results indicate that the two spatially distinct myosin II populations coordinately regulate ovulatory contraction of the myoepithelial sheath.
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Affiliation(s)
- Kanako Ono
- Department of Pathology and Department of Cell Biology, Emory University, Atlanta, GA 30322
| | - Shoichiro Ono
- Department of Pathology and Department of Cell Biology, Emory University, Atlanta, GA 30322
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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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The Rho guanine exchange factor RHGF-2 acts through the Rho-binding kinase LET-502 to mediate embryonic elongation in C. elegans. Dev Biol 2015; 405:250-9. [DOI: 10.1016/j.ydbio.2015.07.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 07/08/2015] [Accepted: 07/11/2015] [Indexed: 12/31/2022]
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20
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Etheridge T, Rahman M, Gaffney CJ, Shaw D, Shephard F, Magudia J, Solomon DE, Milne T, Blawzdziewicz J, Constantin-Teodosiu D, Greenhaff PL, Vanapalli SA, Szewczyk NJ. The integrin-adhesome is required to maintain muscle structure, mitochondrial ATP production, and movement forces in Caenorhabditis elegans. FASEB J 2014; 29:1235-46. [PMID: 25491313 PMCID: PMC4396603 DOI: 10.1096/fj.14-259119] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 11/11/2014] [Indexed: 01/19/2023]
Abstract
The integrin-adhesome network, which contains >150 proteins, is mechano-transducing and located at discreet positions along the cell-cell and cell-extracellular matrix interface. A small subset of the integrin-adhesome is known to maintain normal muscle morphology. However, the importance of the entire adhesome for muscle structure and function is unknown. We used RNA interference to knock down 113 putative Caenorhabditis elegans homologs constituting most of the mammalian adhesome and 48 proteins known to localize to attachment sites in C. elegans muscle. In both cases, we found >90% of components were required for normal muscle mitochondrial structure and/or proteostasis vs. empty vector controls. Approximately half of these, mainly proteins that physically interact with each other, were also required for normal sarcomere and/or adhesome structure. Next we confirmed that the dystrophy observed in adhesome mutants associates with impaired maximal mitochondrial ATP production (P < 0.01), as well as reduced probability distribution of muscle movement forces compared with wild-type animals. Our results show that the integrin-adhesome network as a whole is required for maintaining both muscle structure and function and extend the current understanding of the full complexities of the functional adhesome in vivo.—Etheridge, T., Rahman, M., Gaffney, C. J., Shaw, D., Shephard, F., Magudia, J., Solomon, D. E., Milne, T., Blawzdziewicz, J., Constantin-Teodosiu, D., Greenhaff, P. L., Vanapalli, S. A., Szewczyk, N. J. The integrin-adhesome is required to maintain muscle structure, mitochondrial ATP production, and movement forces in Caenorhabditis elegans.
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Affiliation(s)
- Timothy Etheridge
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Mizanur Rahman
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Christopher J Gaffney
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Debra Shaw
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Freya Shephard
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Jignesh Magudia
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Deepak E Solomon
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Thomas Milne
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Jerzy Blawzdziewicz
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Dumitru Constantin-Teodosiu
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Paul L Greenhaff
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Siva A Vanapalli
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Nathaniel J Szewczyk
- *Department of Sport and Health Science, College of Life and Environmental Sciences, and College of Engineering, Mathematics and Physical Science, University of Exeter, Exeter, United Kingdom; Departments of Chemical Engineering and Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA; Medical Research Council/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Schools of Life Sciences and Medicine, University of Nottingham, Nottingham, United Kingdom; and School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
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Martin E, Harel S, Nkengfac B, Hamiche K, Neault M, Jenna S. pix-1 controls early elongation in parallel with mel-11 and let-502 in Caenorhabditis elegans. PLoS One 2014; 9:e94684. [PMID: 24732978 PMCID: PMC3986101 DOI: 10.1371/journal.pone.0094684] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/17/2014] [Indexed: 12/17/2022] Open
Abstract
Cell shape changes are crucial for metazoan development. During Caenorhabditis elegans embryogenesis, epidermal cell shape changes transform ovoid embryos into vermiform larvae. This process is divided into two phases: early and late elongation. Early elongation involves the contraction of filamentous actin bundles by phosphorylated non-muscle myosin in a subset of epidermal (hypodermal) cells. The genes controlling early elongation are associated with two parallel pathways. The first one involves the rho-1/RHOA-specific effector let-502/Rho-kinase and mel-11/myosin phosphatase regulatory subunit. The second pathway involves the CDC42/RAC-specific effector pak-1. Late elongation is driven by mechanotransduction in ventral and dorsal hypodermal cells in response to body-wall muscle contractions, and involves the CDC42/RAC-specific Guanine-nucleotide Exchange Factor (GEF) pix-1, the GTPase ced-10/RAC and pak-1. In this study, pix-1 is shown to control early elongation in parallel with let-502/mel-11, as previously shown for pak-1. We show that pix-1, pak-1 and let-502 control the rate of elongation, and the antero-posterior morphology of the embryos. In particular, pix-1 and pak-1 are shown to control head, but not tail width, while let-502 controls both head and tail width. This suggests that let-502 function is required throughout the antero-posterior axis of the embryo during early elongation, while pix-1/pak-1 function may be mostly required in the anterior part of the embryo. Supporting this hypothesis we show that low pix-1 expression level in the dorsal-posterior hypodermal cells is required to ensure high elongation rate during early elongation.
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Affiliation(s)
- Emmanuel Martin
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal (UQÀM), Montréal, Québec, Canada
| | - Sharon Harel
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal (UQÀM), Montréal, Québec, Canada
| | - Bernard Nkengfac
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal (UQÀM), Montréal, Québec, Canada
| | - Karim Hamiche
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal (UQÀM), Montréal, Québec, Canada
| | - Mathieu Neault
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal (UQÀM), Montréal, Québec, Canada
| | - Sarah Jenna
- Department of Chemistry, Pharmaqam, Biomed, Université du Québec à Montréal (UQÀM), Montréal, Québec, Canada
- * E-mail:
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Cox-Paulson E, Cannataro V, Gallagher T, Hoffman C, Mantione G, Mcintosh M, Silva M, Vissichelli N, Walker R, Simske J, Ono S, Hoops H. The minus-end actin capping protein, UNC-94/tropomodulin, regulates development of the Caenorhabditis elegans intestine. Dev Dyn 2014; 243:753-64. [PMID: 24677443 DOI: 10.1002/dvdy.24118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 09/25/2013] [Accepted: 01/31/2014] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Tropomodulins are actin-capping proteins that regulate the stability of the slow-growing, minus-ends of actin filaments. The C. elegans tropomodulin homolog, UNC-94, has sequence and functional similarity to vertebrate tropomodulins. We investigated the role of UNC-94 in C. elegans intestinal morphogenesis. RESULTS In the embryonic C. elegans intestine, UNC-94 localizes to the terminal web, an actin- and intermediate filament-rich structure that underlies the apical membrane. Loss of UNC-94 function results in areas of flattened intestinal lumen. In worms homozygous for the strong loss-of-function allele, unc-94(tm724), the terminal web is thinner and the amount of F-actin is reduced, pointing to a role for UNC-94 in regulating the structure of the terminal web. The non-muscle myosin, NMY-1, also localizes to the terminal web, and we present evidence that increasing actomyosin contractility by depleting the myosin phosphatase regulatory subunit, mel-11, can rescue the flattened lumen phenotype of unc-94 mutants. CONCLUSIONS The data support a model in which minus-end actin capping by UNC-94 promotes proper F-actin structure and contraction in the terminal web, yielding proper shape of the intestinal lumen. This establishes a new role for a tropomodulin in regulating lumen shape during tubulogenesis.
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23
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Cram EJ. Mechanotransduction in C. elegans morphogenesis and tissue function. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 126:281-316. [PMID: 25081623 DOI: 10.1016/b978-0-12-394624-9.00012-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mechanobiology is an emerging field that investigates how living cells sense and respond to their physical surroundings. Recent interest in the field has been sparked by the finding that stem cells differentiate along different lineages based on the stiffness of the cell surroundings (Engler et al., 2006), and that metastatic behavior of cancer cells is strongly influenced by the mechanical properties of the surrounding tissue (Kumar and Weaver, 2009). Many questions remain about how cells convert mechanical information, such as viscosity, stiffness of the substrate, or stretch state of the cells, into the biochemical signals that control tissue function. Caenorhabditis elegans researchers are making significant contributions to the understanding of mechanotransduction in vivo. This review summarizes recent insights into the role of mechanical forces in morphogenesis and tissue function. Examples of mechanical regulation across length scales, from the single-celled zygote, to the intercellular coordination that enables cohesive tissue function, to the mechanical influences between tissues, are considered. The power of the C. elegans system as a gene discovery and in vivo quantitative bioimaging platform is enabling an important discoveries in this exciting field.
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Affiliation(s)
- Erin J Cram
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
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24
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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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25
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Guo Y, Chen X, Ellis RE. Evolutionary change within a bipotential switch shaped the sperm/oocyte decision in hermaphroditic nematodes. PLoS Genet 2013; 9:e1003850. [PMID: 24098152 PMCID: PMC3789826 DOI: 10.1371/journal.pgen.1003850] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/17/2013] [Indexed: 01/11/2023] Open
Abstract
A subset of transcription factors like Gli2 and Oct1 are bipotential--they can activate or repress the same target, in response to changing signals from upstream genes. Some previous studies implied that the sex-determination protein TRA-1 might also be bipotential; here we confirm this hypothesis by identifying a co-factor, and use it to explore how the structure of a bipotential switch changes during evolution. First, null mutants reveal that C. briggsae TRR-1 is required for spermatogenesis, RNA interference implies that it works as part of the Tip60 Histone Acetyl Transferase complex, and RT-PCR data show that it promotes the expression of Cbr-fog-3, a gene needed for spermatogenesis. Second, epistasis tests reveal that TRR-1 works through TRA-1, both to activate Cbr-fog-3 and to control the sperm/oocyte decision. Since previous studies showed that TRA-1 can repress fog-3 as well, these observations demonstrate that it is bipotential. Third, TRR-1 also regulates the development of the male tail. Since Cbr-tra-2 Cbr-trr-1 double mutants resemble Cbr-tra-1 null mutants, these two regulatory branches control all tra-1 activity. Fourth, striking differences in the relationship between these two branches of the switch have arisen during recent evolution. C. briggsae trr-1 null mutants prevent hermaphrodite spermatogenesis, but not Cbr-fem null mutants, which disrupt the other half of the switch. On the other hand, C. elegans fem null mutants prevent spermatogenesis, but not Cel-trr-1 mutants. However, synthetic interactions confirm that both halves of the switch exist in each species. Thus, the relationship between the two halves of a bipotential switch can shift rapidly during evolution, so that the same phenotype is produce by alternative, complementary mechanisms.
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Affiliation(s)
- Yiqing Guo
- Department of Molecular Biology, Rowan-SOM and the UMDNJ-SOM, B303 Science Center, Stratford, New Jersey, United States of America
| | - Xiangmei Chen
- Department of Molecular Biology, Rowan-SOM and the UMDNJ-SOM, B303 Science Center, Stratford, New Jersey, United States of America
| | - Ronald E. Ellis
- Department of Molecular Biology, Rowan-SOM and the UMDNJ-SOM, B303 Science Center, Stratford, New Jersey, United States of America
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Vanneste CA, Pruyne D, Mains PE. The role of the formin gene fhod-1 in C. elegans embryonic morphogenesis. WORM 2013; 2:e25040. [PMID: 24778933 PMCID: PMC3875645 DOI: 10.4161/worm.25040] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/10/2013] [Accepted: 05/14/2013] [Indexed: 01/20/2023]
Abstract
During the second half of embryogenesis, the ellipsoidal Caenorhabditis elegans embryo elongates into a long, thin worm. This elongation requires a highly organized cytoskeleton composed of actin microfilaments, microtubules and intermediate filaments throughout the epidermis of the embryo. This architecture allows the embryonic epidermal cells to undergo a smooth muscle-like actin/myosin-based contraction that is redundantly controlled by LET- 502/Rho kinase and MEL-11/myosin phosphatase in one pathway and FEM-2/PP2c phosphatase and PAK-1/p21-activated kinase in a parallel pathway(s). Although actin microfilaments surround the embryo, the force for contraction is generated mainly in the lateral (seam) epidermal cells whose actin microfilaments appear qualitatively different from those in their dorsal/ventral neighbors. We have identified FHOD-1, a formin family actin nucleator, which acts in the lateral epidermis. fhod-1 mutants show microfilament defects in the embryonic lateral epidermal cells and FHOD-1 protein is detected only in those cells. fhod-1 genetic interactions with let-502, mel-11, fem-2 and pak-1 indicate that fhod-1 preferentially regulates those microfilaments acting with let-502 and mel-11, and in parallel to fem-2 and pak-1. Thus, FHOD-1 may contribute to the qualitative differences in microfilaments found in the contractile lateral epidermal cells and their non-contractile dorsal and ventral neighbors. Different microfilament populations may be involved in the different contractile pathways.
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Affiliation(s)
- Chrisotpher A Vanneste
- Department of Biochemistry and Molecular Biology; Alberta Children's Hospital Research Institute; University of Calgary; Calgary, AB Canada
| | - David Pruyne
- Department of Cell and Developmental Biology; State University of New York Upstate Medical University; Syracuse, NY USA
| | - Paul E Mains
- Department of Biochemistry and Molecular Biology; Alberta Children's Hospital Research Institute; University of Calgary; Calgary, AB Canada
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Filamin and phospholipase C-ε are required for calcium signaling in the Caenorhabditis elegans spermatheca. PLoS Genet 2013; 9:e1003510. [PMID: 23671426 PMCID: PMC3650001 DOI: 10.1371/journal.pgen.1003510] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 03/30/2013] [Indexed: 12/05/2022] Open
Abstract
The Caenorhabditis elegans spermatheca is a myoepithelial tube that stores sperm and undergoes cycles of stretching and constriction as oocytes enter, are fertilized, and exit into the uterus. FLN-1/filamin, a stretch-sensitive structural and signaling scaffold, and PLC-1/phospholipase C-ε, an enzyme that generates the second messenger IP3, are required for embryos to exit normally after fertilization. Using GCaMP, a genetically encoded calcium indicator, we show that entry of an oocyte into the spermatheca initiates a distinctive series of IP3-dependent calcium oscillations that propagate across the tissue via gap junctions and lead to constriction of the spermatheca. PLC-1 is required for the calcium release mechanism triggered by oocyte entry, and FLN-1 is required for timely initiation of the calcium oscillations. INX-12, a gap junction subunit, coordinates propagation of the calcium transients across the spermatheca. Gain-of-function mutations in ITR-1/IP3R, an IP3-dependent calcium channel, and loss-of-function mutations in LFE-2, a negative regulator of IP3 signaling, increase calcium release and suppress the exit defect in filamin-deficient animals. We further demonstrate that a regulatory cassette consisting of MEL-11/myosin phosphatase and NMY-1/non-muscle myosin is required for coordinated contraction of the spermatheca. In summary, this study answers long-standing questions concerning calcium signaling dynamics in the C. elegans spermatheca and suggests FLN-1 is needed in response to oocyte entry to trigger calcium release and coordinated contraction of the spermathecal tissue. During organism development and normal physiological function cells sense, integrate, and respond to a variety of cues or signals including biochemical and mechanical stimuli. In this study we used Caenorhabditis elegans, a small transparent worm, to study filamin (FLN-1), a structural protein that may act as a molecular strain gauge. The C. elegans spermatheca is a contractile tube that is stretched during normal function, making it an ideal candidate for study of how cells respond to stretch. Oocytes are ovulated into the spermatheca, fertilized, and then pushed into the uterus by constriction of the spermatheca. The ability of the spermatheca to constrict depends on inositol 1,4,5-triphosphate (IP3), a signaling molecule produced by the enzyme phospholipase C (PLC-1) that triggers calcium release within cells. In animals with mutated FLN-1 or PLC-1 the spermathecal cells fail to constrict. Using genetic analysis and a calcium-sensitive fluorescent protein, we show that FLN-1 functions with PLC-1 to regulate IP3 production, calcium release, and contraction of the spermatheca. Filamin may function to sense stretch caused by entering oocytes and to trigger constriction. These findings establish a link between filamin and calcium signaling that may apply to similar signaling pathways in other systems.
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Maiden SL, Harrison N, Keegan J, Cain B, Lynch AM, Pettitt J, Hardin J. Specific conserved C-terminal amino acids of Caenorhabditis elegans HMP-1/α-catenin modulate F-actin binding independently of vinculin. J Biol Chem 2012; 288:5694-706. [PMID: 23271732 DOI: 10.1074/jbc.m112.438093] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Stable intercellular adhesions formed through the cadherin-catenin complex are important determinants of proper tissue architecture and help maintain tissue integrity during morphogenetic movements in developing embryos. A key regulator of this stability is α-catenin, which connects the cadherin-catenin complex to the actin cytoskeleton. Although the C-terminal F-actin-binding domain of α-catenin has been shown to be crucial for its function, a more detailed in vivo analysis of discrete regions and residues required for actin binding has not been performed. Using Caenorhabditis elegans as a model system, we have characterized mutations in hmp-1/α-catenin that identify HMP-1 residues 687-742 and 826-927, as well as amino acid 802, as critical to the localization of junctional proximal actin during epidermal morphogenesis. We also find that the S823F transition in a hypomorphic allele, hmp-1(fe4), decreases actin binding in vitro. Using hmp-1(fe4) animals in a mutagenesis screen, we were then able to identify 11 intragenic suppressors of hmp-1(fe4) that revert actin binding to wild-type levels. Using homology modeling, we show that these amino acids are positioned at key conserved sites within predicted α-helices in the C terminus. Through the use of transgenic animals, we also demonstrate that HMP-1 residues 315-494, which correspond to a putative mechanotransduction domain that binds vinculin in vertebrate αE-catenin, are not required during epidermal morphogenesis but may aid efficient recruitment of HMP-1 to the junction. Our studies are the first to identify key conserved amino acids in the C terminus of α-catenin that modulate F-actin binding in living embryos of a simple metazoan.
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Affiliation(s)
- Stephanie L Maiden
- Department of Zoology, University of Wisconsin, Madison, Wisconsin 53706, USA
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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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Gally C, Wissler F, Zahreddine H, Quintin S, Landmann F, Labouesse M. Myosin II regulation during C. elegans embryonic elongation: LET-502/ROCK, MRCK-1 and PAK-1, three kinases with different roles. Development 2009; 136:3109-19. [PMID: 19675126 DOI: 10.1242/dev.039412] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Myosin II plays a central role in epithelial morphogenesis; however, its role has mainly been examined in processes involving a single cell type. Here we analyze the structure, spatial requirement and regulation of myosin II during C. elegans embryonic elongation, a process that involves distinct epidermal cells and muscles. We developed novel GFP probes to visualize the dynamics of actomyosin remodeling, and found that the assembly of myosin II filaments, but not actin microfilaments, depends on the myosin regulatory light chain (MLC-4) and essential light chain (MLC-5, which we identified herein). To determine how myosin II regulates embryonic elongation, we rescued mlc-4 mutants with various constructs and found that MLC-4 is essential in a subset of epidermal cells. We show that phosphorylation of two evolutionary conserved MLC-4 serine and threonine residues is important for myosin II activity and organization. Finally, in an RNAi screen for potential myosin regulatory light chain kinases, we found that the ROCK, PAK and MRCK homologs act redundantly. The combined loss of ROCK and PAK, or ROCK and MRCK, completely prevented embryonic elongation, but a constitutively active form of MLC-4 could only rescue a lack of MRCK. This result, together with systematic genetic epistasis tests with a myosin phosphatase mutation, suggests that ROCK and MRCK regulate MLC-4 and the myosin phosphatase. Moreover, we suggest that ROCK and PAK regulate at least one other target essential for elongation, in addition to MLC-4.
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Affiliation(s)
- Christelle Gally
- IGBMC, CNRS/ INSERM/ UdS, 1 rue Laurent Fries, BP.10142, 67400 Illkirch, France
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The N- or C-terminal domains of DSH-2 can activate the C. elegans Wnt/beta-catenin asymmetry pathway. Dev Biol 2009; 328:234-44. [PMID: 19298786 DOI: 10.1016/j.ydbio.2009.01.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 01/12/2009] [Accepted: 01/13/2009] [Indexed: 12/25/2022]
Abstract
Dishevelleds are modular proteins that lie at the crossroads of divergent Wnt signaling pathways. The DIX domain of dishevelleds modulates a beta-catenin destruction complex, and thereby mediates cell fate decisions through differential activation of Tcf transcription factors. The DEP domain of dishevelleds mediates planar polarity of cells within a sheet through regulation of actin modulators. In Caenorhabditis elegans asymmetric cell fate decisions are regulated by asymmetric localization of signaling components in a pathway termed the Wnt/beta-catenin asymmetry pathway. Which domain(s) of Disheveled regulate this pathway is unknown. We show that C. elegans embryos from dsh-2(or302) mutant mothers fail to successfully undergo morphogenesis, but transgenes containing either the DIX or the DEP domain of DSH-2 are sufficient to rescue the mutant phenotype. Embryos lacking zygotic function of SYS-1/beta-catenin, WRM-1/beta-catenin, or POP-1/Tcf show defects similar to dsh-2 mutants, including a loss of asymmetry in some cell fate decisions. Removal of two dishevelleds (dsh-2 and mig-5) leads to a global loss of POP-1 asymmetry, which can be rescued by addition of transgenes containing either the DIX or DEP domain of DSH-2. These results indicate that either the DIX or DEP domain of DSH-2 is capable of activating the Wnt/beta-catenin asymmetry pathway and regulating anterior-posterior fate decisions required for proper morphogenesis.
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Goulding MB, Canman JC, Senning EN, Marcus AH, Bowerman B. Control of nuclear centration in the C. elegans zygote by receptor-independent Galpha signaling and myosin II. ACTA ACUST UNITED AC 2007; 178:1177-91. [PMID: 17893243 PMCID: PMC2064652 DOI: 10.1083/jcb.200703159] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mitotic spindle positioning in the Caenorhabditis elegans zygote involves microtubule-dependent pulling forces applied to centrosomes. In this study, we investigate the role of actomyosin in centration, the movement of the nucleus-centrosome complex (NCC) to the cell center. We find that the rate of wild-type centration depends equally on the nonmuscle myosin II NMY-2 and the Galpha proteins GOA-1/GPA-16. In centration- defective let-99(-) mutant zygotes, GOA-1/GPA-16 and NMY-2 act abnormally to oppose centration. This suggests that LET-99 determines the direction of a force on the NCC that is promoted by Galpha signaling and actomyosin. During wild-type centration, NMY-2-GFP aggregates anterior to the NCC tend to move further anterior, suggesting that actomyosin contraction could pull the NCC. In GOA-1/GPA-16-depleted zygotes, NMY-2 aggregate displacement is reduced and largely randomized, whereas in a let-99(-) mutant, NMY-2 aggregates tend to make large posterior displacements. These results suggest that Galpha signaling and LET-99 control centration by regulating polarized actomyosin contraction.
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Affiliation(s)
- Morgan B Goulding
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA.
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Schmutz C, Stevens J, Spang A. Functions of the novel RhoGAP proteins RGA-3 and RGA-4 in the germ line and in the early embryo of C. elegans. Development 2007; 134:3495-505. [PMID: 17728351 DOI: 10.1242/dev.000802] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We have identified two redundant GTPase activating proteins (GAPs) - RGA-3 and RGA-4 - that regulate Rho GTPase function at the plasma membrane in early Caenorhabditis elegans embryos. Knockdown of both RhoGAPs resulted in extensive membrane ruffling, furrowing and pronounced pseudo-cleavages. In addition, the non-muscle myosin NMY-2 and RHO-1 accumulated on the cortex at sites of ruffling. RGA-3 and RGA-4 are GAPs for RHO-1, but most probably not for CDC-42, because only RHO-1 was epistatic to the two GAPs, and the GAPs had no obvious influence on CDC-42 function. Furthermore, knockdown of either the RHO-1 effector, LET-502, or the exchange factor for RHO-1, ECT-2, alleviated the membrane-ruffling phenotype caused by simultaneous knockdown of both RGA-3 and RGA-4 [rga-3/4 (RNAi)]. GFP::PAR-6 and GFP::PAR-2 were localized at the anterior and posterior part of the early C. elegans embryo, respectively showing that rga-3/4 (RNAi) did not interfere with polarity establishment. Most importantly, upon simultaneous knockdown of RGA-3, RGA-4 and the third RhoGAP present in the early embryo, CYK-4, NMY-2 spread over the entire cortex and GFP::PAR-2 localization at the posterior cortex was greatly diminished. These results indicate that the functions of CYK-4 are temporally and spatially distinct from RGA-3 and RGA-4 (RGA-3/4). RGA-3/4 and CYK-4 also play different roles in controlling LET-502 activation in the germ line, because rga-3/4 (RNAi), but not cyk-4 (RNAi), aggravated the let-502(sb106) phenotype. We propose that RGA-3/4 and CYK-4 control with which effector molecules RHO-1 interacts at particular sites at the cortex in the zygote and in the germ line.
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Affiliation(s)
- Cornelia Schmutz
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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Diogon M, Wissler F, Quintin S, Nagamatsu Y, Sookhareea S, Landmann F, Hutter H, Vitale N, Labouesse M. The RhoGAP RGA-2 and LET-502/ROCK achieve a balance of actomyosin-dependent forces inC. elegansepidermis to control morphogenesis. Development 2007; 134:2469-79. [PMID: 17537791 DOI: 10.1242/dev.005074] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Embryonic morphogenesis involves the coordinate behaviour of multiple cells and requires the accurate balance of forces acting within different cells through the application of appropriate brakes and throttles. In C. elegans, embryonic elongation is driven by Rho-binding kinase (ROCK) and actomyosin contraction in the epidermis. We identify an evolutionary conserved, actin microfilament-associated RhoGAP (RGA-2) that behaves as a negative regulator of LET-502/ROCK. The small GTPase RHO-1 is the preferred target of RGA-2 in vitro, and acts between RGA-2 and LET-502 in vivo. Two observations show that RGA-2 acts in dorsal and ventral epidermal cells to moderate actomyosin tension during the first half of elongation. First,time-lapse microscopy shows that loss of RGA-2 induces localised circumferentially oriented pulling on junctional complexes in dorsal and ventral epidermal cells. Second, specific expression of RGA-2 in dorsal/ventral, but not lateral, cells rescues the embryonic lethality of rga-2 mutants. We propose that actomyosin-generated tension must be moderated in two out of the three sets of epidermal cells surrounding the C. elegans embryo to achieve morphogenesis.
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Affiliation(s)
- Marie Diogon
- IGBMC, CNRS/INSERM/ULP, 1 rue Laurent Fries, BP.10142, 67400 Illkirch, France
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Rho-kinase regulates tissue morphogenesis via non-muscle myosin and LIM-kinase during Drosophila development. BMC DEVELOPMENTAL BIOLOGY 2006; 6:38. [PMID: 16882341 PMCID: PMC1552057 DOI: 10.1186/1471-213x-6-38] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Accepted: 08/01/2006] [Indexed: 12/14/2022]
Abstract
Background The Rho-kinases (ROCKs) are major effector targets of the activated Rho GTPase that have been implicated in many of the Rho-mediated effects on cell shape and movement via their ability to affect acto-myosin contractility. The role of ROCKs in cell shape change and motility suggests a potentially important role for Rho-ROCK signaling in tissue morphogenesis during development. Indeed, in Drosophila, a single ROCK ortholog, DRok, has been identified and has been found to be required for establishing planar cell polarity. Results We have examined a potential role for DRok in additional aspects of tissue morphogenesis using an activated form of the protein in transgenic flies. Our findings demonstrate that DRok activity can influence multiple morphogenetic processes, including eye and wing development. Furthermore, genetic studies reveal that Drok interacts with multiple downstream effectors of the Rho GTPase signaling pathway, including non-muscle myosin heavy chain, adducin, and Diaphanous in those developmental processes. Finally, in overexpression studies, we determined that Drok and Drosophila Lim-kinase interact in the developing nervous system. Conclusion These findings indicate widespread diverse roles for DRok in tissue morphogenesis during Drosophila development, in which multiple DRok substrates appear to be required.
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Marston DJ, Goldstein B. Actin-based forces driving embryonic morphogenesis in Caenorhabditis elegans. Curr Opin Genet Dev 2006; 16:392-8. [PMID: 16782324 DOI: 10.1016/j.gde.2006.06.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Accepted: 06/08/2006] [Indexed: 01/27/2023]
Abstract
Morphogenesis is the process by which multicellular organisms transform themselves from a ball of cells into an organized animal. Certain virtues of Caenorhabditis elegans make it an excellent model system for the study of this process: it is genetically tractable, develops as a transparent embryo with small cell-numbers, and yet still contains all the major tissues typical of animals. Furthermore, certain morphogenetic events are also amenable to study by direct manipulation of the cells involved. Given these advantages, it has been possible to use C. elegans to investigate the different ways in which the actin cytoskeleton drives the cellular rearrangements underlying morphogenesis, through regulated polymerization or actomyosin contraction. Recent insights from this system have determined the involvement in morphogenesis of key proteins, including the actin-regulating WASP and Ena proteins, potential guidance molecules such as the Eph and Robo receptors, and the cell-cell signaling proteins of the Wnt pathway.
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Affiliation(s)
- Daniel J Marston
- Department of Biology, CB3280, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA.
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Verdier V, Johndrow JE, Betson M, Chen GC, Hughes DA, Parkhurst SM, Settleman J. Drosophila Rho-kinase (DRok) is required for tissue morphogenesis in diverse compartments of the egg chamber during oogenesis. Dev Biol 2006; 297:417-32. [PMID: 16887114 PMCID: PMC2504748 DOI: 10.1016/j.ydbio.2006.05.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 05/11/2006] [Accepted: 05/15/2006] [Indexed: 11/16/2022]
Abstract
The Rho-kinases are widely utilized downstream targets of the activated Rho GTPase that have been directly implicated in many aspects of Rho-dependent effects on F-actin assembly, acto-myosin contractility, and microtubule stability, and consequently play an essential role in regulating cell shape, migration, polarity, and division. We have determined that the single closely related Drosophila Rho-kinase ortholog, DRok, is required for several aspects of oogenesis, including maintaining the integrity of the oocyte cortex, actin-mediated tethering of nurse cell nuclei, "dumping" of nurse cell contents into the oocyte, establishment of oocyte polarity, and the trafficking of oocyte yolk granules. These defects are associated with abnormalities in DRok-dependent actin dynamics and appear to be mediated by multiple downstream effectors of activated DRok that have previously been implicated in oogenesis. DRok regulates at least one of these targets, the membrane cytoskeletal cross-linker DMoesin, via a direct phosphorylation that is required to promote localization of DMoesin to the oocyte cortex. The collective oogenesis defects associated with DRok deficiency reveal its essential role in multiple aspects of proper oocyte formation and suggest that DRok defines a novel class of oogenesis determinants that function as key regulators of several distinct actin-dependent processes required for proper tissue morphogenesis.
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Affiliation(s)
- Valerie Verdier
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 Street, Charlestown, MA 02129, USA
| | - James E. Johndrow
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, A1-162, PO Box 19024, Seattle, WA 98109-1024, USA
| | | | - Guang-Chao Chen
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 Street, Charlestown, MA 02129, USA
| | - David A. Hughes
- The Faculty of Life Sciences, The University of Manchester, Sackville Street, Manchester, United Kingdom
| | - Susan M. Parkhurst
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, A1-162, PO Box 19024, Seattle, WA 98109-1024, USA
| | - Jeffrey Settleman
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 Street, Charlestown, MA 02129, USA
- Corresponding author, Telephone 617-724-9556, Fax: 617-726-7808,
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Hill RC, de Carvalho CE, Salogiannis J, Schlager B, Pilgrim D, Haag ES. Genetic flexibility in the convergent evolution of hermaphroditism in Caenorhabditis nematodes. Dev Cell 2006; 10:531-8. [PMID: 16580997 DOI: 10.1016/j.devcel.2006.02.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 01/25/2006] [Accepted: 02/01/2006] [Indexed: 11/28/2022]
Abstract
The self-fertile hermaphrodites of C. elegans and C. briggsae evolved from female ancestors by acquiring limited spermatogenesis. Initiation of C. elegans hermaphrodite spermatogenesis requires germline translational repression of the female-promoting gene tra-2, which allows derepression of the three male-promoting fem genes. Cessation of hermaphrodite spermatogenesis requires fem-3 translational repression. We show that C. briggsae requires neither fem-2 nor fem-3 for hermaphrodite development, and that XO Cb-fem-2/3 animals are transformed into hermaphrodites, not females as in C. elegans. Exhaustive screens for Cb-tra-2 suppressors identified another 75 fem-like mutants, but all are self-fertile hermaphrodites rather than females. Control of hermaphrodite spermatogenesis therefore acts downstream of the fem genes in C. briggsae. The outwardly similar hermaphrodites of C. elegans and C. briggsae thus achieve self-fertility via intervention at different points in the core sex determination pathway. These findings are consistent with convergent evolution of hermaphroditism, which is marked by considerable developmental genetic flexibility.
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Affiliation(s)
- Robin Cook Hill
- Department of Biology, University of Maryland, College Park, 20742, USA
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Aracena J, González M, Zuñiga A, Mendez MA, Cambiazo V. Regulatory network for cell shape changes during Drosophila ventral furrow formation. J Theor Biol 2006; 239:49-62. [PMID: 16139845 DOI: 10.1016/j.jtbi.2005.07.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Revised: 07/15/2005] [Accepted: 07/18/2005] [Indexed: 01/04/2023]
Abstract
Rapid and sequential cell shape changes take place during the formation of the ventral furrow (VF) at the beginning of Drosophila gastrulation. At the cellular level, this morphogenetic event demands close coordination of the proteins involved in actin cytoskeletal reorganization. In order to construct a regulatory network that describes these cell shape changes, we have used published genetic and molecular data for 18 genes encoding transcriptional regulators and signaling pathway components. Based on the dynamic behavior of this network we explored the hypothesis that the combination of three recognizable phenotypes describing wild type or mutant cell types, during VF invagination, correspond to different activation states of a specific set of these gene products, which are point attractors of the regulatory network. From our results, we recognize missing components in the regulatory network and suggest alternative pathways in the regulation of cell shape changes during VF formation.
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Affiliation(s)
- Julio Aracena
- Centro de Modelamiento Matemático, UMR-CNRS 2071, Universidad de Chile, Casilla 170-3, Santiago, Chile
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Praitis V, Ciccone E, Austin J. SMA-1 spectrin has essential roles in epithelial cell sheet morphogenesis in C. elegans. Dev Biol 2005; 283:157-70. [PMID: 15890334 DOI: 10.1016/j.ydbio.2005.04.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2004] [Revised: 03/24/2005] [Accepted: 04/06/2005] [Indexed: 01/27/2023]
Abstract
During Caenorhabditis elegans development, the embryo acquires its vermiform shape due to changes in the shape of epithelial cells, a process that requires an apically localized actin cytoskeleton. We show that SMA-1, an ortholog of beta(H)-spectrin required for normal morphogenesis, localizes to the apical membrane of epithelial cells when these cells are rapidly elongating. In spc-1 alpha-spectrin mutants, SMA-1 localizes to the apical membrane but its organization is altered, consistent with the hypothesis these proteins act together to form an apically localized spectrin-based membrane skeleton (SBMS). SMA-1 is required to maintain the association between actin and the apical membrane; sma-1 mutant embryos fail to elongate because actin, which provides the driving force for cell shape change, dissociates from the apical membrane skeleton during morphogenesis. Analysis of sma-1 expression constructs and mutant strains indicates SMA-1 maintains the association between actin and the apical membrane via interactions at its N-terminus and this activity is independent of alpha-spectrin. SMA-1 also preserves dynamic changes in the organization of the apical membrane skeleton. Taken together, our results show the SMA-1 SBMS plays a dynamic role in converting changes in actin organization into changes in epithelial cell shape during C. elegans embryogenesis.
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Affiliation(s)
- Vida Praitis
- Biology Department, Grinnell College, Grinnell, IA 50112, USA.
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Kanada M, Nagasaki A, Uyeda TQP. Adhesion-dependent and contractile ring-independent equatorial furrowing during cytokinesis in mammalian cells. Mol Biol Cell 2005; 16:3865-72. [PMID: 15944220 PMCID: PMC1182322 DOI: 10.1091/mbc.e05-03-0233] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Myosin II-dependent contraction of the contractile ring drives equatorial furrowing during cytokinesis in animal cells. Nonetheless, myosin II-null cells of the cellular slime mold Dictyostelium divide efficiently when adhering to substrates by making use of polar traction forces. Here, we show that in the presence of 30 microM blebbistatin, a potent myosin II inhibitor, normal rat kidney (NRK) cells adhering to fibronectin-coated surfaces formed equatorial furrows and divided in a manner strikingly similar to myosin II-null Dictyostelium cells. Such blebbistatin-resistant cytokinesis was absent in partially detached NRK cells and was disrupted in adherent cells if the advance of their polar lamellipodia was disturbed by neighboring cells. Y-27632 (40 microM), which inhibits Rho-kinase, was similar to 30 microM blebbistatin in that it inhibited cytokinesis of partially detached NRK cells but only prolonged furrow ingression in attached cells. In the presence of 100 microM blebbistatin, most NRK cells that initiated anaphase formed tight furrows, although scission never occurred. Adherent HT1080 fibrosarcoma cells also formed equatorial furrows efficiently in the presence of 100 microM blebbistatin. These results provide direct evidence for adhesion-dependent, contractile ring-independent equatorial furrowing in mammalian cells and demonstrate the importance of substrate adhesion for cytokinesis.
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Affiliation(s)
- Masamitsu Kanada
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
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42
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Van Fürden D, Johnson K, Segbert C, Bossinger O. The C. elegans ezrin-radixin-moesin protein ERM-1 is necessary for apical junction remodelling and tubulogenesis in the intestine. Dev Biol 2004; 272:262-76. [PMID: 15242805 DOI: 10.1016/j.ydbio.2004.05.012] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Revised: 03/24/2004] [Accepted: 05/02/2004] [Indexed: 12/31/2022]
Abstract
Members of the ezrin-radixin-moesin (ERM) family of proteins have been found to serve as linkers between membrane proteins and the F-actin cytoskeleton in many organisms. We used RNA interference (RNAi) approach to assay ERM proteins of the Caenorhabditis elegans genome for a possible involvement in apical junction (AJ) assembly or positioning. We identify erm-1 as the only ERM protein required for development and show, by multiple RNA interference, that additional four-point one, ezrin-radixin-moesin (FERM) domain-containing proteins cannot compensate for the depletion of ERM-1. ERM-1 is expressed in most if not all cells of the embryo at low levels but is upregulated in epithelia, like the intestine. ERM-1 protein co-localizes with F-actin and the intermediate filament protein IFB-2 at the apical cell cortex. ERM-1 depletion results in intestine-specific phenotypes like lumenal constrictions or even obstructions. This phenotype arises after epithelial polarization of intestinal cells and can be monitored using markers of the apical junction. We show that the initial steps of epithelial polarization in the intestine are not affected in erm-1(RNAi) embryos but the positioning of apical junction proteins to an apico-lateral position arrests prematurely or fails, resulting in multiple obstructions of the intestinal flow after hatching. Mechanistically, this phenotype might be due to an altered apical cytoskeleton because the apical enrichment of F-actin filaments is lost specifically in the intestine. ERM-1 is the first protein of the apical membrane domain affecting junction remodelling in C. elegans. ERM-1 interacts genetically with the catenin-cadherin system but not with the DLG-1 (Discs large)-dependent establishment of the apical junction.
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Affiliation(s)
- Daniela Van Fürden
- Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, D-40225, Germany
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43
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Lee A, Treisman JE. Excessive Myosin activity in mbs mutants causes photoreceptor movement out of the Drosophila eye disc epithelium. Mol Biol Cell 2004; 15:3285-95. [PMID: 15075368 PMCID: PMC452583 DOI: 10.1091/mbc.e04-01-0057] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Neuronal cells must extend a motile growth cone while maintaining the cell body in its original position. In migrating cells, myosin contraction provides the driving force that pulls the rear of the cell toward the leading edge. We have characterized the function of myosin light chain phosphatase, which down-regulates myosin activity, in Drosophila photoreceptor neurons. Mutations in the gene encoding the myosin binding subunit of this enzyme cause photoreceptors to drop out of the eye disc epithelium and move toward and through the optic stalk. We show that this phenotype is due to excessive phosphorylation of the myosin regulatory light chain Spaghetti squash rather than another potential substrate, Moesin, and that it requires the nonmuscle myosin II heavy chain Zipper. Myosin binding subunit mutant cells continue to express apical epithelial markers and do not undergo ectopic apical constriction. In addition, mutant cells in the wing disc remain within the epithelium and differentiate abnormal wing hairs. We suggest that excessive myosin activity in photoreceptor neurons may pull the cell bodies toward the growth cones in a process resembling normal cell migration.
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Affiliation(s)
- Arnold Lee
- Skirball Institute for Biomolecular Medicine and Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA
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44
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Piekny AJ, Johnson JLF, Cham GD, Mains PE. TheCaenorhabditis elegansnonmuscle myosin genesnmy-1andnmy-2function as redundant components of thelet-502/Rho-binding kinase andmel-11/myosin phosphatase pathway during embryonic morphogenesis. Development 2003; 130:5695-704. [PMID: 14522875 DOI: 10.1242/dev.00807] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Rho-binding kinase and the myosin phosphatase targeting subunit regulate nonmuscle contractile events in higher eukaryotes. Genetic evidence indicates that the C. elegans homologs regulate embryonic morphogenesis by controlling the actin-mediated epidermal cell shape changes that transform the spherical embryo into a long, thin worm. LET-502/Rho-binding kinase triggers elongation while MEL-11/myosin phosphatase targeting subunit inhibits this contractile event. We describe mutations in the nonmuscle myosin heavy chain gene nmy-1 that were isolated as suppressors of the mel-11hypercontraction phenotype. However, a nmy-1 null allele displays elongation defects less severe than mutations in let-502 or in the single nonmuscle myosin light chain gene mlc-4. This results because nmy-1 is partially redundant with another nonmuscle myosin heavy chain, nmy-2, which was previously known only for its role in anterior/posterior polarity and cytokinesis in the early embryo. At the onset of elongation, NMY-1 forms filamentous-like structures similar to actin, and LET-502 is interspersed with these structures, where it may trigger contraction. MEL-11, which inhibits elongation, is initially cytoplasmic. In response to LET-502 activity, MEL-11 becomes sequestered away from the contractile apparatus, to the plasma membrane, when elongation commences. Upon completion of morphogenesis, MEL-11 again appears in the cytoplasm where it may halt actin/myosin contraction.
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Affiliation(s)
- Alisa J Piekny
- Genes and Development Research Group and Department of Biochemistry and Molecular Biology, University of Calgary, 3330 Hospital Dr NW, Calgary, AB, Canada, T2N 4N1
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Ding M, Goncharov A, Jin Y, Chisholm AD. C. elegansankyrin repeat protein VAB-19 is a component of epidermal attachment structures and is essential for epidermal morphogenesis. Development 2003; 130:5791-801. [PMID: 14534136 DOI: 10.1242/dev.00791] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Elongation of the epidermis of the nematode Caenorhabditis elegansinvolves both actomyosin-mediated changes in lateral epidermal cell shape and body muscle attachment to dorsal and ventral epidermal cells via intermediate-filament/hemidesmosome structures. vab-19 mutants are defective in epidermal elongation and muscle attachment to the epidermis. VAB-19 is a member of a conserved family of ankyrin repeat-containing proteins that includes the human tumor suppressor Kank. In epidermal cells,VAB-19::GFP localizes with components of epidermal attachment structures. In vab-19 mutants, epidermal attachment structures form normally but do not remain localized to muscle-adjacent regions of the epidermis. VAB-19 localization requires function of the transmembrane attachment structure component Myotactin. vab-19 mutants also display aberrant actin organization in the epidermis. Loss of function in the spectrin SMA-1 partly bypasses the requirement for VAB-19 in elongation, suggesting that VAB-19 and SMA-1/spectrin might play antagonistic roles in regulation of the actin cytoskeleton.
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Affiliation(s)
- Mei Ding
- Sinsheimer Laboratories, Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Cruz, CA 95064, USA
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Somlyo AP, Somlyo AV. Ca2+ sensitivity of smooth muscle and nonmuscle myosin II: modulated by G proteins, kinases, and myosin phosphatase. Physiol Rev 2003; 83:1325-58. [PMID: 14506307 DOI: 10.1152/physrev.00023.2003] [Citation(s) in RCA: 1528] [Impact Index Per Article: 72.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Ca2+ sensitivity of smooth muscle and nonmuscle myosin II reflects the ratio of activities of myosin light-chain kinase (MLCK) to myosin light-chain phosphatase (MLCP) and is a major, regulated determinant of numerous cellular processes. We conclude that the majority of phenotypes attributed to the monomeric G protein RhoA and mediated by its effector, Rho-kinase (ROK), reflect Ca2+ sensitization: inhibition of myosin II dephosphorylation in the presence of basal (Ca2+ dependent or independent) or increased MLCK activity. We outline the pathway from receptors through trimeric G proteins (Galphaq, Galpha12, Galpha13) to activation, by guanine nucleotide exchange factors (GEFs), from GDP. RhoA. GDI to GTP. RhoA and hence to ROK through a mechanism involving association of GEF, RhoA, and ROK in multimolecular complexes at the lipid cell membrane. Specific domains of GEFs interact with trimeric G proteins, and some GEFs are activated by Tyr kinases whose inhibition can inhibit Rho signaling. Inhibition of MLCP, directly by ROK or by phosphorylation of the phosphatase inhibitor CPI-17, increases phosphorylation of the myosin II regulatory light chain and thus the activity of smooth muscle and nonmuscle actomyosin ATPase and motility. We summarize relevant effects of p21-activated kinase, LIM-kinase, and focal adhesion kinase. Mechanisms of Ca2+ desensitization are outlined with emphasis on the antagonism between cGMP-activated kinase and the RhoA/ROK pathway. We suggest that the RhoA/ROK pathway is constitutively active in a number of organs under physiological conditions; its aberrations play major roles in several disease states, particularly impacting on Ca2+ sensitization of smooth muscle in hypertension and possibly asthma and on cancer neoangiogenesis and cancer progression. It is a potentially important therapeutic target and a subject for translational research.
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Affiliation(s)
- Andrew P Somlyo
- Dept. of Molecular Physiology and Biological Physics, Univ. of Virginia, PO Box 800736, Charlottesville, VA 22908-0736.
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Abstract
Myosins are a superfamily of actin-dependent molecular motor proteins, among which the bipolar filament forming myosins II have been the most studied. The activity of smooth muscle/non-muscle myosin II is regulated by phosphorylation of the regulatory light chains, that in turn is modulated by the antagonistic activity of myosin light chain kinase and myosin light chain phosphatase. The phosphatase activity is mainly regulated through phosphorylation of its myosin binding subunit MYPT. To identify the function of these phosphorylation events, we have molecularly characterized the Drosophila homologue of MYPT, and analyzed its mutant phenotypes. We find that Drosophila MYPT is required for cell sheet movement during dorsal closure, morphogenesis of the eye, and ring canal growth during oogenesis. Our results indicate that the regulation of the phosphorylation of myosin regulatory light chains, or dynamic activation and inactivation of myosin II, is essential for its various functions during many developmental processes.
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Affiliation(s)
- Change Tan
- Department of Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Beth Stronach
- Department of Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
- Howard Hughes Medical Institute, 200 Longwood Avenue, Boston, MA 02115, USA
- Author for correspondence ()
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Piekny AJ, Mains PE. Rho-binding kinase (LET-502) and myosin phosphatase (MEL-11) regulate cytokinesis in the earlyCaenorhabditis elegansembryo. J Cell Sci 2002; 115:2271-82. [PMID: 12006612 DOI: 10.1242/jcs.115.11.2271] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Rho-binding kinase and myosin phosphatase regulate the contraction of actomyosin filaments in non-muscle and smooth muscle cells. Previously, we described the role of C. elegans genes encoding Rho-binding kinase(let-502) and myosin phosphatase targeting subunit (mel-11)in epidermal cell-shape changes that drive morphogenesis and in spermathecal contraction. Here we analyze their roles in a third contractile event,cytokinesis within early embryos. We demonstrate that these genes function together to regulate the rate of cleavage furrow contraction, with Rho-binding kinase/LET-502 mediating contraction, whereas myosin phosphatase/MEL-11 acts as a brake to contraction: early embryonic cleavage often fails or is slowed when let-502 is mutated, whereas mel-11 mutations result in ectopic furrowing and faster furrow ingression. These phenotypes correspond to changes in the levels of phosphorylated regulatory non-muscle myosin light chain (rMLC). The gene products of let-502 and mel-11colocalize at cleavage furrows, and their mutations alleviate one another's defects. rMLC is phosphorylated in let-502; mel-11 double mutants,indicating that a kinase is able to phosphorylate rMLC in the absence of both LET-502 and MEL-11. Genetic and molecular epistasis experiments place LET-502 and MEL-11 in a cytokinetic pathway. LET-502 and MEL-11 regulate the activity of non-muscle myosin after actin, non-muscle myosin heavy chain/NMY-2,regulatory non-muscle myosin light chain/MLC-4 and early formin/CYK-1 have formed a contractile ring. Proteins including Rho GTPase activating protein/CYK-4 and late CYK-1, which are required for late stages of cytokinesis, function downstream of LET-502 and MEL-11.
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Affiliation(s)
- Alisa J Piekny
- Genes and Development Research Group, Department of Biochemistry and Molecular Biology, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada, T2N 4N1
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Abstract
Cytokinesis creates two daughter cells endowed with a complete set of chromosomes and cytoplasmic organelles. This conceptually simple event is mediated by a complex and dynamic interplay between the microtubules of the mitotic spindle, the actomyosin cytoskeleton, and membrane fusion events. For many decades the study of cytokinesis was driven by morphological studies on specimens amenable to physical manipulation. The studies led to great insights into the cellular structures that orchestrate cell division, but the underlying molecular machinery was largely unknown. Molecular and genetic approaches have now allowed the initial steps in the development of a molecular understanding of this fundamental event in the life of a cell. This review provides an overview of the literature on cytokinesis with a particular emphasis on the molecular pathways involved in the division of animal cells.
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Affiliation(s)
- M Glotzer
- Research Institute of Molecular Pathology (IMP), Dr. Bohr-Gasse 1, A-1030 Vienna, Austria.
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50
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O'Keefe L, Somers WG, Harley A, Saint R. The pebble GTP exchange factor and the control of cytokinesis. Cell Struct Funct 2001; 26:619-26. [PMID: 11942617 DOI: 10.1247/csf.26.619] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Several G proteins of the Rho family have been shown to be required for cytokinesis. The activity of these proteins is regulated by GTP exchange factors (GEFs), which stimulate GDP/GTP exchange, and by GTPase activating proteins (GAPs), which suppress activity by stimulating the intrinsic GTPase activity. The role of Rho family members during cytokinesis is likely to be determined by their spatial and temporal interactions with these factors. Here we focus on the role of the pebble (pbl) gene of Drosophila melanogaster, a RhoGEF that is required for cytokinesis. We summarise the evidence that the primary target of PBL is Rho1 and describe genetic approaches to elucidating the function of PBL and identifying other components of the PBL-activated Rho signalling pathway.
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Affiliation(s)
- L O'Keefe
- Centre for the Molecular Genetics of Development and Dept. of Molecular Biosciences, Adelaide University, SA, Australia
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