1
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Sun Y, Huang Y, Hao Z, Zhang S, Tian Q. MRLC controls apoptotic cell death and functions to regulate epidermal development during planarian regeneration and homeostasis. Cell Prolif 2024; 57:e13524. [PMID: 37357415 PMCID: PMC10771114 DOI: 10.1111/cpr.13524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 06/02/2023] [Accepted: 06/13/2023] [Indexed: 06/27/2023] Open
Abstract
Adult stem cells (ASCs) are pluripotent cells with the capacity to self-renew and constantly replace lost cells due to physiological turnover or injury. Understanding the molecular mechanisms of the precise coordination of stem cell proliferation and proper cell fate decision is important to regeneration and organismal homeostasis. The planarian epidermis provides a highly tractable model to study ASC complex dynamic due to the distinct spatiotemporal differentiation stages during lineage development. Here, we identified the myosin regulatory light chain (MRLC) homologue in the Dugesia japonica transcriptome. We found high expression levels of MRLC in wound region during regeneration and also expressed in late epidermal progenitors as an essential regulator of the lineage from neoblasts to mature epidermal cells. We investigated the function of MRLC using in situ hybridization, real-time polymerase chain reaction and double fluorescent and uncovered the potential mechanism. Knockdown of MRLC leads to a remarkable increase in cell death, causes severe abnormalities during regeneration and homeostasis and eventually leads to animal death. The global decrease in epidermal cell in MRLC RNAi animals induces accelerated epidermal proliferation and differentiation. Additionally, we find that MRLC is co-expressed with cdc42 and acts cooperatively to control the epidermal lineage development by affecting cell death. Our results uncover an important role of MRLC, as an inhibitor of apoptosis, involves in epidermal development.
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Affiliation(s)
- Yujia Sun
- School of Life SciencesZhengzhou UniversityZhengzhouHenanChina
| | - Yongding Huang
- School of Life SciencesZhengzhou UniversityZhengzhouHenanChina
| | - Zhitai Hao
- Department of Biochemistry and Molecular PharmacologyNew York University, School of MedicineNew YorkUSA
| | - Shoutao Zhang
- School of Life SciencesZhengzhou UniversityZhengzhouHenanChina
- Longhu Laboratory of Advanced ImmunologyZhengzhouHenanChina
| | - Qingnan Tian
- School of Life SciencesZhengzhou UniversityZhengzhouHenanChina
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2
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Lepeta K, Roubinet C, Bauer M, Vigano MA, Aguilar G, Kanca O, Ochoa-Espinosa A, Bieli D, Cabernard C, Caussinus E, Affolter M. Engineered kinases as a tool for phosphorylation of selected targets in vivo. J Cell Biol 2022; 221:213463. [PMID: 36102907 PMCID: PMC9477969 DOI: 10.1083/jcb.202106179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 05/19/2022] [Accepted: 07/27/2022] [Indexed: 11/22/2022] Open
Abstract
Reversible protein phosphorylation by kinases controls a plethora of processes essential for the proper development and homeostasis of multicellular organisms. One main obstacle in studying the role of a defined kinase–substrate interaction is that kinases form complex signaling networks and most often phosphorylate multiple substrates involved in various cellular processes. In recent years, several new approaches have been developed to control the activity of a given kinase. However, most of them fail to regulate a single protein target, likely hiding the effect of a unique kinase–substrate interaction by pleiotropic effects. To overcome this limitation, we have created protein binder-based engineered kinases that permit a direct, robust, and tissue-specific phosphorylation of fluorescent fusion proteins in vivo. We show the detailed characterization of two engineered kinases based on Rho-associated protein kinase (ROCK) and Src. Expression of synthetic kinases in the developing fly embryo resulted in phosphorylation of their respective GFP-fusion targets, providing for the first time a means to direct the phosphorylation to a chosen and tagged target in vivo. We presume that after careful optimization, the novel approach we describe here can be adapted to other kinases and targets in various eukaryotic genetic systems to regulate specific downstream effectors.
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Affiliation(s)
| | - Chantal Roubinet
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK 2
| | - Milena Bauer
- Biozentrum, University of Basel, Basel, Switzerland 1
| | | | | | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 3
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3
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Hunt EL, Rai H, Harris TJC. SCAR/WAVE complex recruitment to a supracellular actomyosin cable by myosin activators and a junctional Arf-GEF during Drosophila dorsal closure. Mol Biol Cell 2022; 33. [DOI: 10.1091/mbc.e22-03-0107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Expansive Arp2/3 actin networks and contractile actomyosin networks can be spatially and temporally segregated within the cell, but the networks also interact closely at various sites, including adherens junctions. However, molecular mechanisms coordinating these interactions remain unclear. We found that the SCAR/WAVE complex, an Arp2/3 activator, is enriched at adherens junctions of the leading edge actomyosin cable during Drosophila dorsal closure. Myosin activators were both necessary and sufficient for SCAR/WAVE accumulation at leading edge junctions. The same myosin activators were previously shown to recruit the cytohesin Arf-GEF Steppke to these sites, and mammalian studies have linked Arf small G protein signaling to SCAR/WAVE activation. During dorsal closure, we find that Steppke is required for SCAR/WAVE enrichment at the actomyosin-linked junctions. Arp2/3 also localizes to adherens junctions of the leading edge cable. We propose that junctional actomyosin activity acts through Steppke to recruit SCAR/WAVE and Arp2/3 for regulation of the leading edge supracellular actomyosin cable during dorsal closure.
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Affiliation(s)
- Erin L. Hunt
- Department of Cell & Systems Biology, University of Toronto
| | - Hrishika Rai
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata
- International Visiting Graduate Students Study Abroad Program, University of Toronto
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4
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Sharma S, Rikhy R. Spatiotemporal recruitment of RhoGTPase protein GRAF inhibits actomyosin ring constriction in Drosophila cellularization. eLife 2021; 10:63535. [PMID: 33835025 PMCID: PMC8081525 DOI: 10.7554/elife.63535] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 03/31/2021] [Indexed: 11/18/2022] Open
Abstract
Actomyosin contractility is regulated by Rho-GTP in cell migration, cytokinesis and morphogenesis in embryo development. Whereas Rho activation by Rho-GTP exchange factor (GEF), RhoGEF2, is well known in actomyosin contractility during cytokinesis at the base of invaginating membranes in Drosophila cellularization, Rho inhibition by RhoGTPase-activating proteins (GAPs) remains to be studied. We have found that the RhoGAP, GRAF, inhibits actomyosin contractility during cellularization. GRAF is enriched at the cleavage furrow tip during actomyosin assembly and initiation of ring constriction. Graf depletion shows increased Rho-GTP, increased Myosin II and ring hyper constriction dependent upon the loss of the RhoGTPase domain. GRAF and RhoGEF2 are present in a balance for appropriate activation of actomyosin ring constriction. RhoGEF2 depletion and abrogation of Myosin II activation in Rho kinase mutants suppress the Graf hyper constriction defect. Therefore, GRAF recruitment restricts Rho-GTP levels in a spatiotemporal manner for inhibiting actomyosin contractility during cellularization.
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Affiliation(s)
- Swati Sharma
- Biology, Indian Institute of Science Education and Research, Pune, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Pune, India
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5
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López-Gay JM, Nunley H, Spencer M, di Pietro F, Guirao B, Bosveld F, Markova O, Gaugue I, Pelletier S, Lubensky DK, Bellaïche Y. Apical stress fibers enable a scaling between cell mechanical response and area in epithelial tissue. Science 2020; 370:370/6514/eabb2169. [PMID: 33060329 DOI: 10.1126/science.abb2169] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 08/13/2020] [Indexed: 12/14/2022]
Abstract
Biological systems tailor their properties and behavior to their size throughout development and in numerous aspects of physiology. However, such size scaling remains poorly understood as it applies to cell mechanics and mechanosensing. By examining how the Drosophila pupal dorsal thorax epithelium responds to morphogenetic forces, we found that the number of apical stress fibers (aSFs) anchored to adherens junctions scales with cell apical area to limit larger cell elongation under mechanical stress. aSFs cluster Hippo pathway components, thereby scaling Hippo signaling and proliferation with area. This scaling is promoted by tricellular junctions mediating an increase in aSF nucleation rate and lifetime in larger cells. Development, homeostasis, and repair entail epithelial cell size changes driven by mechanical forces; our work highlights how, in turn, mechanosensitivity scales with cell size.
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Affiliation(s)
- Jesús M López-Gay
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France.,Sorbonne Universités, UPMC Univ Paris 06, CNRS, CNRS UMR 3215, INSERM U934, F-75005 Paris, France
| | - Hayden Nunley
- Biophysics Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Meryl Spencer
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Florencia di Pietro
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France.,Sorbonne Universités, UPMC Univ Paris 06, CNRS, CNRS UMR 3215, INSERM U934, F-75005 Paris, France
| | - Boris Guirao
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France.,Sorbonne Universités, UPMC Univ Paris 06, CNRS, CNRS UMR 3215, INSERM U934, F-75005 Paris, France
| | - Floris Bosveld
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France.,Sorbonne Universités, UPMC Univ Paris 06, CNRS, CNRS UMR 3215, INSERM U934, F-75005 Paris, France
| | - Olga Markova
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France.,Sorbonne Universités, UPMC Univ Paris 06, CNRS, CNRS UMR 3215, INSERM U934, F-75005 Paris, France
| | - Isabelle Gaugue
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France.,Sorbonne Universités, UPMC Univ Paris 06, CNRS, CNRS UMR 3215, INSERM U934, F-75005 Paris, France
| | - Stéphane Pelletier
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France.,Sorbonne Universités, UPMC Univ Paris 06, CNRS, CNRS UMR 3215, INSERM U934, F-75005 Paris, France
| | - David K Lubensky
- Biophysics Program, University of Michigan, Ann Arbor, MI 48109, USA. .,Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yohanns Bellaïche
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France. .,Sorbonne Universités, UPMC Univ Paris 06, CNRS, CNRS UMR 3215, INSERM U934, F-75005 Paris, France
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6
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Perez-Vale KZ, Peifer M. Orchestrating morphogenesis: building the body plan by cell shape changes and movements. Development 2020; 147:dev191049. [PMID: 32917667 PMCID: PMC7502592 DOI: 10.1242/dev.191049] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During embryonic development, a simple ball of cells re-shapes itself into the elaborate body plan of an animal. This requires dramatic cell shape changes and cell movements, powered by the contractile force generated by actin and myosin linked to the plasma membrane at cell-cell and cell-matrix junctions. Here, we review three morphogenetic events common to most animals: apical constriction, convergent extension and collective cell migration. Using the fruit fly Drosophila as an example, we discuss recent work that has revealed exciting new insights into the molecular mechanisms that allow cells to change shape and move without tearing tissues apart. We also point out parallel events at work in other animals, which suggest that the mechanisms underlying these morphogenetic processes are conserved.
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Affiliation(s)
- Kia Z Perez-Vale
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Mark Peifer
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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7
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Dey B, Rikhy R. DE-cadherin and Myosin II balance regulates furrow length for onset of polygon shape in syncytial Drosophila embryos. J Cell Sci 2020; 133:jcs240168. [PMID: 32265269 DOI: 10.1242/jcs.240168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 03/26/2020] [Indexed: 08/31/2023] Open
Abstract
Cell shape morphogenesis, from spherical to polygonal, occurs in epithelial cell formation in metazoan embryogenesis. In syncytial Drosophila embryos, the plasma membrane incompletely surrounds each nucleus and is organized as a polygonal epithelial-like array. Each cortical syncytial division cycle shows a circular to polygonal plasma membrane transition along with furrow extension between adjacent nuclei from interphase to metaphase. In this study, we assess the relative contribution of DE-cadherin (also known as Shotgun) and Myosin II (comprising Zipper and Spaghetti squash in flies) at the furrow to polygonal shape transition. We show that polygonality initiates during each cortical syncytial division cycle when the furrow extends from 4.75 to 5.75 μm. Polygon plasma membrane organization correlates with increased junctional tension, increased DE-cadherin and decreased Myosin II mobility. DE-cadherin regulates furrow length and polygonality. Decreased Myosin II activity allows for polygonality to occur at a lower length than controls. Increased Myosin II activity leads to loss of lateral furrow formation and complete disruption of the polygonal shape transition. Our studies show that DE-cadherin-Myosin II balance regulates an optimal lateral membrane length during each syncytial cycle for polygonal shape transition.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Bipasha Dey
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune, 411008, India
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8
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An Actomyosin-Arf-GEF Negative Feedback Loop for Tissue Elongation under Stress. Curr Biol 2017; 27:2260-2270.e5. [DOI: 10.1016/j.cub.2017.06.038] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 05/15/2017] [Accepted: 06/14/2017] [Indexed: 02/06/2023]
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9
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Protein phosphatases 1 and 2A and their naturally occurring inhibitors: current topics in smooth muscle physiology and chemical biology. J Physiol Sci 2017; 68:1-17. [PMID: 28681362 PMCID: PMC5754374 DOI: 10.1007/s12576-017-0556-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 06/27/2017] [Indexed: 12/26/2022]
Abstract
Protein phosphatases 1 and 2A (PP1 and PP2A) are the most ubiquitous and abundant serine/threonine phosphatases in eukaryotic cells. They play fundamental roles in the regulation of various cellular functions. This review focuses on recent advances in the functional studies of these enzymes in the field of smooth muscle physiology. Many naturally occurring protein phosphatase inhibitors with different relative PP1/PP2A affinities have been discovered and are widely used as powerful research tools. Current topics in the chemical biology of PP1/PP2A inhibitors are introduced and discussed, highlighting the identification of the gene cluster responsible for the biosynthesis of calyculin A in a symbiont microorganism of a marine sponge.
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10
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Vasquez CG, Heissler SM, Billington N, Sellers JR, Martin AC. Drosophila non-muscle myosin II motor activity determines the rate of tissue folding. eLife 2016; 5. [PMID: 28035903 PMCID: PMC5201417 DOI: 10.7554/elife.20828] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 12/08/2016] [Indexed: 12/15/2022] Open
Abstract
Non-muscle cell contractility is critical for tissues to adopt shape changes. Although, the non-muscle myosin II holoenzyme (myosin) is a molecular motor that powers contraction of actin cytoskeleton networks, recent studies have questioned the importance of myosin motor activity cell and tissue shape changes. Here, combining the biochemical analysis of enzymatic and motile properties for purified myosin mutants with in vivo measurements of apical constriction for the same mutants, we show that in vivo constriction rate scales with myosin motor activity. We show that so-called phosphomimetic mutants of the Drosophila regulatory light chain (RLC) do not mimic the phosphorylated RLC state in vitro. The defect in the myosin motor activity in these mutants is evident in developing Drosophila embryos where tissue recoil following laser ablation is decreased compared to wild-type tissue. Overall, our data highlights that myosin activity is required for rapid cell contraction and tissue folding in developing Drosophila embryos. DOI:http://dx.doi.org/10.7554/eLife.20828.001
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Affiliation(s)
- Claudia G Vasquez
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Sarah M Heissler
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Neil Billington
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - James R Sellers
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
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11
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Duque J, Gorfinkiel N. Integration of actomyosin contractility with cell-cell adhesion during dorsal closure. Development 2016; 143:4676-4686. [PMID: 27836966 DOI: 10.1242/dev.136127] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 10/27/2016] [Indexed: 02/01/2023]
Abstract
In this work, we combine genetic perturbation, time-lapse imaging and quantitative image analysis to investigate how pulsatile actomyosin contractility drives cell oscillations, apical cell contraction and tissue closure during morphogenesis of the amnioserosa, the main force-generating tissue during the dorsal closure in Drosophila We show that Myosin activity determines the oscillatory and contractile behaviour of amnioserosa cells. Reducing Myosin activity prevents cell shape oscillations and reduces cell contractility. By contrast, increasing Myosin activity increases the amplitude of cell shape oscillations and the time cells spend in the contracted phase relative to the expanded phase during an oscillatory cycle, promoting cell contractility and tissue closure. Furthermore, we show that in AS cells, Rok controls Myosin foci formation and Mbs regulates not only Myosin phosphorylation but also adhesion dynamics through control of Moesin phosphorylation, showing that Mbs coordinates actomyosin contractility with cell-cell adhesion during amnioserosa morphogenesis.
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Affiliation(s)
- Julia Duque
- Centro de Biología Molecular 'Severo Ochoa', CSIC-UAM, Cantoblanco, Madrid 28049, Spain
| | - Nicole Gorfinkiel
- Centro de Biología Molecular 'Severo Ochoa', CSIC-UAM, Cantoblanco, Madrid 28049, Spain
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12
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Amnioserosa cell constriction but not epidermal actin cable tension autonomously drives dorsal closure. Nat Cell Biol 2016; 18:1161-1172. [PMID: 27749821 DOI: 10.1038/ncb3420] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 09/08/2016] [Indexed: 12/15/2022]
Abstract
Tissue morphogenesis requires coordination of multiple force-producing components. During dorsal closure in fly embryogenesis, an epidermis opening closes. A tensioned epidermal actin/MyosinII cable, which surrounds the opening, produces a force that is thought to combine with another MyosinII force mediating apical constriction of the amnioserosa cells that fill the opening. A model proposing that each force could autonomously drive dorsal closure was recently challenged by a model in which the two forces combine in a ratchet mechanism. Acute force elimination via selective MyosinII depletion in one or the other tissue shows that the amnioserosa tissue autonomously drives dorsal closure while the actin/MyosinII cable cannot. These findings exclude both previous models, although a contribution of the ratchet mechanism at dorsal closure onset remains likely. This shifts the current view of dorsal closure being a combinatorial force-component system to a single tissue-driven closure event.
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13
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Schwayer C, Sikora M, Slováková J, Kardos R, Heisenberg CP. Actin Rings of Power. Dev Cell 2016; 37:493-506. [DOI: 10.1016/j.devcel.2016.05.024] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/24/2016] [Accepted: 05/25/2016] [Indexed: 12/21/2022]
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14
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Vasquez CG, Tworoger M, Martin AC. Dynamic myosin phosphorylation regulates contractile pulses and tissue integrity during epithelial morphogenesis. ACTA ACUST UNITED AC 2014; 206:435-50. [PMID: 25092658 PMCID: PMC4121972 DOI: 10.1083/jcb.201402004] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Apical constriction is a cell shape change that promotes epithelial bending. Activation of nonmuscle myosin II (Myo-II) by kinases such as Rho-associated kinase (Rok) is important to generate contractile force during apical constriction. Cycles of Myo-II assembly and disassembly, or pulses, are associated with apical constriction during Drosophila melanogaster gastrulation. It is not understood whether Myo-II phosphoregulation organizes contractile pulses or whether pulses are important for tissue morphogenesis. Here, we show that Myo-II pulses are associated with pulses of apical Rok. Mutants that mimic Myo-II light chain phosphorylation or depletion of myosin phosphatase inhibit Myo-II contractile pulses, disrupting both actomyosin coalescence into apical foci and cycles of Myo-II assembly/disassembly. Thus, coupling dynamic Myo-II phosphorylation to upstream signals organizes contractile Myo-II pulses in both space and time. Mutants that mimic Myo-II phosphorylation undergo continuous, rather than incremental, apical constriction. These mutants fail to maintain intercellular actomyosin network connections during tissue invagination, suggesting that Myo-II pulses are required for tissue integrity during morphogenesis.
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Affiliation(s)
- Claudia G Vasquez
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Mike Tworoger
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
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15
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Ferreira T, Prudêncio P, Martinho RG. Drosophila protein kinase N (Pkn) is a negative regulator of actin-myosin activity during oogenesis. Dev Biol 2014; 394:277-91. [PMID: 25131196 DOI: 10.1016/j.ydbio.2014.08.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 08/08/2014] [Accepted: 08/09/2014] [Indexed: 02/05/2023]
Abstract
Nurse cell dumping is an actin-myosin based process, where 15 nurse cells of a given egg chamber contract and transfer their cytoplasmic content through the ring canals into the growing oocyte. We isolated two mutant alleles of protein kinase N (pkn) and showed that Pkn negatively-regulates activation of the actin-myosin cytoskeleton during the onset of dumping. Using live-cell imaging analysis we observed that nurse cell dumping rates sharply increase during the onset of fast dumping. Such rate increase was severely impaired in pkn mutant nurse cells due to excessive nurse cell actin-myosin activity and/or loss of tissue integrity. Our work demonstrates that the transition between slow and fast dumping is a discrete event, with at least a five to six-fold dumping rate increase. We show that Pkn negatively regulates nurse cell actin-myosin activity. This is likely to be important for directional cytoplasmic flow. We propose Pkn provides a negative feedback loop to help avoid excessive contractility after local activation of Rho GTPase.
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Affiliation(s)
- Tânia Ferreira
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal
| | - Pedro Prudêncio
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal; Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; IBB-Institute for Biotechnology and Bioengineering, Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Rui Gonçalo Martinho
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal; Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; IBB-Institute for Biotechnology and Bioengineering, Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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16
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Dippold RP, Fisher SA. A bioinformatic and computational study of myosin phosphatase subunit diversity. Am J Physiol Regul Integr Comp Physiol 2014; 307:R256-70. [PMID: 24898838 PMCID: PMC4121627 DOI: 10.1152/ajpregu.00145.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 05/25/2014] [Indexed: 01/01/2023]
Abstract
Variability in myosin phosphatase (MP) subunits may provide specificity in signaling pathways that regulate muscle tone. We utilized public databases and computational algorithms to investigate the phylogenetic diversity of MP regulatory (PPP1R12A-C) and inhibitory (PPP1R14A-D) subunits. The comparison of exonic coding sequences and expression data confirmed or refuted the existence of isoforms and their tissue-specific expression in different model organisms. The comparison of intronic and exonic sequences identified potential expressional regulatory elements. As examples, smooth muscle MP regulatory subunit (PPP1R12A) is highly conserved through evolution. Its alternative exon E24 is present in fish through mammals with two invariant features: 1) a reading frame shift generating a premature termination codon and 2) a hexanucleotide sequence adjacent to the 3' splice site hypothesized to be a novel suppressor of exon splicing. A characteristic of the striated muscle MP regulatory subunit (PPP1R12B) locus is numerous and phylogenetically variable transcriptional start sites. In fish this locus only codes for the small (M21) subunit, suggesting the primordial function of this gene. Inhibitory subunits show little intragenic variability; their diversity is thought to have arisen by expansion and tissue-specific expression of different gene family members. We demonstrate differences in the regulatory landscape between smooth muscle enriched (PPP1R14A) and more ubiquitously expressed (PPP1R14B) family members and identify deeply conserved intronic sequence and predicted transcriptional cis-regulatory elements. This bioinformatic and computational study has uncovered a number of attributes of MP subunits that supports selection of ideal model organisms and testing of hypotheses regarding their physiological significance and regulated expression.
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Affiliation(s)
- Rachael P Dippold
- Department of Medicine, Cardiology, University of Maryland Baltimore, Baltimore, Maryland
| | - Steven A Fisher
- Department of Medicine, Cardiology, University of Maryland Baltimore, Baltimore, Maryland
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17
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Jayashankar V, Nguyen MJ, Carr BW, Zheng DC, Rosales JB, Rosales JB, Weiser DC. Protein phosphatase 1 β paralogs encode the zebrafish myosin phosphatase catalytic subunit. PLoS One 2013; 8:e75766. [PMID: 24040418 PMCID: PMC3770619 DOI: 10.1371/journal.pone.0075766] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 08/19/2013] [Indexed: 12/21/2022] Open
Abstract
Background The myosin phosphatase is a highly conserved regulator of actomyosin contractility. Zebrafish has emerged as an ideal model system to study the invivo role of myosin phosphatase in controlling cell contractility, cell movement and epithelial biology. Most work in zebrafish has focused on the regulatory subunit of the myosin phosphatase called Mypt1. In this work, we examined the critical role of Protein Phosphatase 1, PP1, the catalytic subunit of the myosin phosphatase. Methodology/Principal Findings We observed that in zebrafish two paralogous genes encoding PP1β, called ppp1cba and ppp1cbb, are both broadly expressed during early development. Furthermore, we found that both gene products interact with Mypt1 and assemble an active myosin phosphatase complex. In addition, expression of this complex results in dephosphorylation of the myosin regulatory light chain and large scale rearrangements of the actin cytoskeleton. Morpholino knock-down of ppp1cba and ppp1cbb results in severe defects in morphogenetic cell movements during gastrulation through loss of myosin phosphatase function. Conclusions/Significance Our work demonstrates that zebrafish have two genes encoding PP1β, both of which can interact with Mypt1 and assemble an active myosin phosphatase. In addition, both genes are required for convergence and extension during gastrulation and correct dosage of the protein products is required.
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Affiliation(s)
- Vaishali Jayashankar
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Michael J. Nguyen
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Brandon W. Carr
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Dale C. Zheng
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Joseph B. Rosales
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Joshua B. Rosales
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Douglas C. Weiser
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
- * E-mail:
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18
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Yamamoto S, Bayat V, Bellen HJ, Tan C. Protein phosphatase 1ß limits ring canal constriction during Drosophila germline cyst formation. PLoS One 2013; 8:e70502. [PMID: 23936219 PMCID: PMC3723691 DOI: 10.1371/journal.pone.0070502] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 06/20/2013] [Indexed: 12/15/2022] Open
Abstract
Germline cyst formation is essential for the propagation of many organisms including humans and flies. The cytoplasm of germline cyst cells communicate with each other directly via large intercellular bridges called ring canals. Ring canals are often derived from arrested contractile rings during incomplete cytokinesis. However how ring canal formation, maintenance and growth are regulated remains unclear. To better understand this process, we carried out an unbiased genetic screen in Drosophila melanogaster germ cells and identified multiple alleles of flapwing (flw), a conserved serine/threonine-specific protein phosphatase. Flw had previously been reported to be unnecessary for early D. melanogaster oogenesis using a hypomorphic allele. We found that loss of Flw leads to over-constricted nascent ring canals and subsequently tiny mature ring canals, through which cytoplasmic transfer from nurse cells to the oocyte is impaired, resulting in small, non-functional eggs. Flw is expressed in germ cells undergoing incomplete cytokinesis, completely colocalized with the Drosophila myosin binding subunit of myosin phosphatase (DMYPT). This colocalization, together with genetic interaction studies, suggests that Flw functions together with DMYPT to negatively regulate myosin activity during ring canal formation. The identification of two subunits of the tripartite myosin phosphatase as the first two main players required for ring canal constriction indicates that tight regulation of myosin activity is essential for germline cyst formation and reproduction in D. melanogaster and probably other species as well.
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Affiliation(s)
- Shinya Yamamoto
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America
| | - Vafa Bayat
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hugo J. Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Change Tan
- Division of Biological Sciences, Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
- * E-mail:
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19
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Moon W, Matsuzaki F. Aurora A kinase negatively regulates Rho-kinase by phosphorylation in vivo. Biochem Biophys Res Commun 2013; 435:610-5. [PMID: 23685146 DOI: 10.1016/j.bbrc.2013.05.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 05/07/2013] [Indexed: 10/26/2022]
Abstract
Aurora-A kinase (AurA) is a key regulator of cellular processes involving microtubules. It has also been implicated in actin-dependent events, but the mechanisms that underlie the processes are not fully understood. Here we provide genetic and biochemical evidence suggesting that AurA negatively regulates Drok, the only known Rho-kinase orthologue in Drosophila. AurA directly phosphorylates Drok in vitro, and the overexpression of the nonphosphorylatable forms of Drok in vivo causes similar, but much stronger effects than that of wild-type Drok. The defects induced by the nonphosphorylatable forms of Drok are compensated by reducing the function of myosin downstream. Thus, phosphorylation of Drok by AurA normally suppresses Drok activity. We propose that AurA directly regulates actin-dependent processes by phosphorylating Rho-kinase.
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Affiliation(s)
- Woongjoon Moon
- Laboratory for Cell Asymmetry, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe 650 0047, Japan
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20
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Iwasaki T, Katayama T, Kohama K, Endo Y, Sawasaki T. Myosin phosphatase is inactivated by caspase-3 cleavage and phosphorylation of myosin phosphatase targeting subunit 1 during apoptosis. Mol Biol Cell 2013; 24:748-56. [PMID: 23345589 PMCID: PMC3596246 DOI: 10.1091/mbc.e11-08-0740] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
This study indicates that myosin phosphatase in apoptotic cells is inactivated by the cleavage and the phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1). The results suggest that down-regulation of MYPT1 promotes hyperphosphorylation of myosin II during apoptosis. In nonapoptotic cells, the phosphorylation level of myosin II is constantly maintained by myosin kinases and myosin phosphatase. During apoptosis, caspase-3–activated Rho-associated protein kinase I triggers hyperphosphorylation of myosin II, leading to membrane blebbing. Although inhibition of myosin phosphatase could also contribute to myosin II phosphorylation, little is known about the regulation of myosin phosphatase in apoptosis. In this study, we have demonstrated that, in apoptotic cells, the myosin-binding domain of myosin phosphatase targeting subunit 1 (MYPT1) is cleaved by caspase-3 at Asp-884, and the cleaved MYPT1 is strongly phosphorylated at Thr-696 and Thr-853, phosphorylation of which is known to inhibit myosin II binding. Expression of the caspase-3 cleaved form of MYPT1 that lacked the C-terminal end in HeLa cells caused the dissociation of MYPT1 from actin stress fibers. The dephosphorylation activity of myosin phosphatase immunoprecipitated from the apoptotic cells was lower than that from the nonapoptotic control cells. These results suggest that down-regulation of MYPT1 may play a role in promoting hyperphosphorylation of myosin II by inhibiting the dephosphorylation of myosin II during apoptosis.
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Affiliation(s)
- Takahiro Iwasaki
- Cell-Free Science and Technology Research Center and Venture Business Laboratory, Ehime University, Matsuyama, Ehime 790-8577, Japan
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21
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Ríos-Barrera LD, Riesgo-Escovar JR. Regulating cell morphogenesis: The drosophila jun N-terminal kinase pathway. Genesis 2012; 51:147-62. [DOI: 10.1002/dvg.22354] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Revised: 10/14/2012] [Accepted: 10/19/2012] [Indexed: 12/15/2022]
Affiliation(s)
- Luis Daniel Ríos-Barrera
- Developmental Neurobioloy and Neurophysiology Department; Instituto de Neurobiología; Universidad Nacional Autónoma de México; Boulevard Juriquilla #3001; Querétaro, Querétaro; México; c.p. 76230
| | - Juan Rafael Riesgo-Escovar
- Developmental Neurobioloy and Neurophysiology Department; Instituto de Neurobiología; Universidad Nacional Autónoma de México; Boulevard Juriquilla #3001; Querétaro, Querétaro; México; c.p. 76230
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22
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Sen A, Nagy-Zsvér-Vadas Z, Krahn MP. Drosophila PATJ supports adherens junction stability by modulating Myosin light chain activity. ACTA ACUST UNITED AC 2012; 199:685-98. [PMID: 23128243 PMCID: PMC3494860 DOI: 10.1083/jcb.201206064] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The assembly and consolidation of the adherens junctions (AJs) are key events in the establishment of an intact epithelium. However, AJs are further modified to obtain flexibility for cell migration and morphogenetic movements. Intact AJs in turn are a prerequisite for the establishment and maintenance of apical-basal polarity in epithelial cells. In this study, we report that the conserved PDZ (PSD95, Discs large, ZO-1) domain-containing protein PATJ (Pals1-associated tight junction protein) was not per se crucial for the maintenance of apical-basal polarity in Drosophila melanogaster epithelial cells but rather regulated Myosin localization and phosphorylation. PATJ directly bound to the Myosin-binding subunit of Myosin phosphatase and decreased Myosin dephosphorylation, resulting in activated Myosin. Thereby, PATJ supports the stability of the Zonula Adherens. Notably, weakening of AJ in a PATJ mutant epithelium led first to a loss of Myosin from the AJ, subsequently to a disassembly of the AJ, and finally, to a loss of apical-basal polarity and disruption of the tissue.
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Affiliation(s)
- Arnab Sen
- Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany
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23
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Belacortu Y, Paricio N. Drosophila as a model of wound healing and tissue regeneration in vertebrates. Dev Dyn 2011; 240:2379-404. [PMID: 21953647 DOI: 10.1002/dvdy.22753] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2011] [Indexed: 11/11/2022] Open
Abstract
Understanding the molecular basis of wound healing and regeneration in vertebrates is one of the main challenges in biology and medicine. This understanding will lead to medical advances allowing accelerated tissue repair after wounding, rebuilding new tissues/organs and restoring homeostasis. Drosophila has emerged as a valuable model for studying these processes because the genetic networks and cytoskeletal machinery involved in epithelial movements occurring during embryonic dorsal closure, larval imaginal disc fusion/regeneration, and epithelial repair are similar to those acting during wound healing and regeneration in vertebrates. Recent studies have also focused on the use of Drosophila adult stem cells to maintain tissue homeostasis. Here, we review how Drosophila has contributed to our understanding of these processes, primarily through live-imaging and genetic tools that are impractical in mammals. Furthermore, we highlight future research areas where this insect may provide novel insights and potential therapeutic strategies for wound healing and regeneration.
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Affiliation(s)
- Yaiza Belacortu
- Departamento de Genética, Facultad CC Biológicas, Universidad de Valencia, Burjasot, Spain
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24
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Cooper MT, Kennison JA. Molecular genetic analyses of polytene chromosome region 72A-D in Drosophila melanogaster reveal a gene desert in 72D. PLoS One 2011; 6:e23509. [PMID: 21853143 PMCID: PMC3154481 DOI: 10.1371/journal.pone.0023509] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 07/19/2011] [Indexed: 11/18/2022] Open
Abstract
We have investigated a region of ∼310 kb of genomic DNA within polytene chromosome subdivisions 72A to 72D of Drosophila melanogaster. This region includes 57 predicted protein-coding genes. Seventeen of these genes are in six clusters that appear to have arisen by tandem duplication. Within this region we found 23 complementation groups that are essential for zygotic viability, and we have identified the transcription units for 18 of the 23. We also found a 55 kb region in 72D that is nonessential. Flies deficient for this region are viable and fertile. Within this nonessential region are 48 DNA sequences of 12 to 33 base pairs that are completely conserved among 12 distantly related Drosophila species. These sequences do not have the evolutionary signature of conserved protein-coding DNA sequences, nor do they appear to encode microRNAs, however, the strong selection suggests functions in wild populations that are not apparent in laboratory cultures. This region resembles dispensable gene deserts previously characterized in the mouse genome.
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Affiliation(s)
- Monica T. Cooper
- Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - James A. Kennison
- Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
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25
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Matsubayashi Y, Razzell W, Martin P. 'White wave' analysis of epithelial scratch wound healing reveals how cells mobilise back from the leading edge in a myosin-II-dependent fashion. J Cell Sci 2011; 124:1017-21. [PMID: 21402875 DOI: 10.1242/jcs.080853] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Collective cell migration is absolutely essential for a wide variety of physiological episodes including the re-epithelialisation component of tissue repair. However, the investigation of such processes has been frustrated by difficulties in quantitatively analysing the behaviours of a large body of cells within a migrating epithelial sheet, which previously required manually tracking a large number of individual cells, or using advanced computational techniques. Here, we describe a novel and simpler image subtraction method with which we can visualise and quantify collective cell mobilisation as a 'white wave' that propagates back from the leading edge of a scratch-wounded monolayer of cultured epithelial cells. Using this technique, we show that actomyosin constriction negatively regulates cell mobilisation and that the advancement of cell sheets and the mobilisation of rows of cells behind their leading edges are independently regulated. We also show that there is a finite limit to the number of rows of cells mobilised after wounding. Moreover, our data suggest that enhancing cell mobilisation, by release from myosin II contractility, accelerates the healing of large wounds in the long term, thus raising the possibility that the cell mobilisation 'wave' we reveal here might be a therapeutic target for improving wound healing.
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Affiliation(s)
- Yutaka Matsubayashi
- School of Biochemistry, Faculty of Medical and Veterinary Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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26
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Wang X, Ward RE. Sec61alpha is required for dorsal closure during Drosophila embryogenesis through its regulation of Dpp signaling. Dev Dyn 2010; 239:784-97. [PMID: 20112345 DOI: 10.1002/dvdy.22219] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
During dorsal closure in Drosophila, signaling events in the dorsalmost row of epidermal cells (DME cells) direct the migration of lateral epidermal sheets towards the dorsal midline where they fuse to enclose the embryo. A Jun amino-terminal kinase (JNK) cascade in the DME cells induces the expression of Decapentaplegic (Dpp). Dpp signaling then regulates the cytoskeleton in the DME cells and amnioserosa to affect the cell shape changes necessary to complete dorsal closure. We identified a mutation in Sec61alpha that specifically perturbs dorsal closure. Sec61alpha encodes the main subunit of the translocon complex for co-translational import of proteins into the ER. JNK signaling is normal in Sec61alpha mutant embryos, but Dpp signaling is attenuated and the DME cells fail to maintain an actinomyosin cable as epithelial migration fails. Consistent with this model, dorsal closure is rescued in Sec61alpha mutant embryos by an activated form of the Dpp receptor Thick veins.
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Affiliation(s)
- Xiaochen Wang
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA
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27
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Ong S, Foote C, Tan C. Mutations of DMYPT cause over constriction of contractile rings and ring canals during Drosophila germline cyst formation. Dev Biol 2010; 346:161-9. [DOI: 10.1016/j.ydbio.2010.06.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 06/03/2010] [Indexed: 12/30/2022]
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28
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Neubueser D, Hipfner DR. Overlapping roles of Drosophila Drak and Rok kinases in epithelial tissue morphogenesis. Mol Biol Cell 2010; 21:2869-79. [PMID: 20573980 DOI: 10.1091/mbc.e10-04-0328] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Dynamic regulation of cytoskeletal contractility through phosphorylation of the nonmuscle Myosin-II regulatory light chain (MRLC) provides an essential source of tension for shaping epithelial tissues. Rho GTPase and its effector kinase ROCK have been implicated in regulating MRLC phosphorylation in vivo, but evidence suggests that other mechanisms must be involved. Here, we report the identification of a single Drosophila homologue of the Death-associated protein kinase (DAPK) family, called Drak, as a regulator of MRLC phosphorylation. Based on analysis of null mutants, we find that Drak broadly promotes proper morphogenesis of epithelial tissues during development. Drak activity is largely redundant with that of the Drosophila ROCK orthologue, Rok, such that it is essential only when Rok levels are reduced. We demonstrate that these two kinases synergistically promote phosphorylation of Spaghetti squash (Sqh), the Drosophila MRLC orthologue, in vivo. The lethality of drak/rok mutants can be rescued by restoring Sqh activity, indicating that Sqh is the critical common effector of these two kinases. These results provide the first evidence that DAPK family kinases regulate actin dynamics in vivo and identify Drak as a novel component of the signaling networks that shape epithelial tissues.
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Affiliation(s)
- Dagmar Neubueser
- Institut de recherches cliniques de Montréal, Montreal, QC, Canada
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29
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Left-right asymmetric morphogenesis of the anterior midgut depends on the activation of a non-muscle myosin II in Drosophila. Dev Biol 2010; 344:693-706. [PMID: 20553709 DOI: 10.1016/j.ydbio.2010.05.501] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 05/19/2010] [Accepted: 05/20/2010] [Indexed: 11/22/2022]
Abstract
Many animals exhibit stereotypical left-right (LR) asymmetry in their internal organs. The mechanisms of LR axis formation required for the subsequent LR asymmetric development are well understood, especially in some vertebrates. However, the molecular mechanisms underlying LR asymmetric morphogenesis, particularly how mechanical force is integrated into the LR asymmetric morphogenesis of organs, are poorly understood. Here, we identified zipper (zip), encoding a Drosophila non-muscle myosin II (myosin II) heavy chain, as a gene required for LR asymmetric development of the embryonic anterior midgut (AMG). Myosin II is known to directly generate mechanical force in various types of cells during morphogenesis and cell migration. We found that myosin II was involved in two events in the LR asymmetric development of the AMG. First, it introduced an LR bias to the directional position of circular visceral muscle (CVMU) cells, which externally cover the midgut epithelium. Second, it was required for the LR-biased rotation of the AMG. Our results suggest that myosin II in CVMU cells plays a crucial role in generating the force leading to LR asymmetric morphogenesis. Taken together with previous studies in vertebrates, the involvement of myosin II in LR asymmetric morphogenesis might be conserved evolutionarily.
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30
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Gutzman JH, Sive H. Epithelial relaxation mediated by the myosin phosphatase regulator Mypt1 is required for brain ventricle lumen expansion and hindbrain morphogenesis. Development 2010; 137:795-804. [PMID: 20147380 DOI: 10.1242/dev.042705] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We demonstrate that in the zebrafish hindbrain, cell shape, rhombomere morphogenesis and, unexpectedly, brain ventricle lumen expansion depend on the contractile state of the neuroepithelium. The hindbrain neural tube opens in a specific sequence, with initial separation along the midline at rhombomere boundaries, subsequent openings within rhombomeres and eventual coalescence of openings into the hindbrain ventricle lumen. A mutation in the myosin phosphatase regulator mypt1 results in a small ventricle due to impaired stretching of the surrounding neuroepithelium. Although initial hindbrain opening remains normal, mypt1 mutant rhombomeres do not undergo normal morphological progression. Three-dimensional reconstruction demonstrates cell shapes within rhombomeres and at rhombomere boundaries are abnormal in mypt1 mutants. Wild-type cell shape requires that surrounding cells are also wild type, whereas mutant cell shape is autonomously regulated. Supporting the requirement for regulation of myosin function during hindbrain morphogenesis, wild-type embryos show dynamic levels of phosphorylated myosin regulatory light chain (pMRLC). By contrast, mutants show continuously high pMRLC levels, with concentration of pMRLC and myosin II at the apical side of the epithelium, and myosin II and actin concentration at rhombomere boundaries. Brain ventricle lumen expansion, rhombomere morphology and cell shape are rescued by inhibition of myosin II function, indicating that each defect is a consequence of overactive myosin. We suggest that the epithelium must ;relax', via activity of myosin phosphatase, to allow for normal hindbrain morphogenesis and expansion of the brain ventricular lumen. Epithelial relaxation might be a widespread strategy to facilitate tube inflation in many organs.
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Affiliation(s)
- Jennifer H Gutzman
- Whitehead Institute for Biochemical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
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31
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Systematic identification of genes that regulate neuronal wiring in the Drosophila visual system. PLoS Genet 2008; 4:e1000085. [PMID: 18516287 PMCID: PMC2377342 DOI: 10.1371/journal.pgen.1000085] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Accepted: 04/30/2008] [Indexed: 11/19/2022] Open
Abstract
Forward genetic screens in model organisms are an attractive means to identify those genes involved in any complex biological process, including neural circuit assembly. Although mutagenesis screens are readily performed to saturation, gene identification rarely is, being limited by the considerable effort generally required for positional cloning. Here, we apply a systematic positional cloning strategy to identify many of the genes required for neuronal wiring in the Drosophila visual system. From a large-scale forward genetic screen selecting for visual system wiring defects with a normal retinal pattern, we recovered 122 mutations in 42 genetic loci. For 6 of these loci, the underlying genetic lesions were previously identified using traditional methods. Using SNP-based mapping approaches, we have now identified 30 additional genes. Neuronal phenotypes have not previously been reported for 20 of these genes, and no mutant phenotype has been previously described for 5 genes. The genes encode a variety of proteins implicated in cellular processes such as gene regulation, cytoskeletal dynamics, axonal transport, and cell signalling. We conducted a comprehensive phenotypic analysis of 35 genes, scoring wiring defects according to 33 criteria. This work demonstrates the feasibility of combining large-scale gene identification with large-scale mutagenesis in Drosophila, and provides a comprehensive overview of the molecular mechanisms that regulate visual system wiring.
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32
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Todi SV, Sivan-Loukianova E, Jacobs JS, Kiehart DP, Eberl DF. Myosin VIIA, important for human auditory function, is necessary for Drosophila auditory organ development. PLoS One 2008; 3:e2115. [PMID: 18461180 PMCID: PMC2362849 DOI: 10.1371/journal.pone.0002115] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Accepted: 03/26/2008] [Indexed: 12/21/2022] Open
Abstract
Background Myosin VIIA (MyoVIIA) is an unconventional myosin necessary for vertebrate audition [1]–[5]. Human auditory transduction occurs in sensory hair cells with a staircase-like arrangement of apical protrusions called stereocilia. In these hair cells, MyoVIIA maintains stereocilia organization [6]. Severe mutations in the Drosophila MyoVIIA orthologue, crinkled (ck), are semi-lethal [7] and lead to deafness by disrupting antennal auditory organ (Johnston's Organ, JO) organization [8]. ck/MyoVIIA mutations result in apical detachment of auditory transduction units (scolopidia) from the cuticle that transmits antennal vibrations as mechanical stimuli to JO. Principal Findings Using flies expressing GFP-tagged NompA, a protein required for auditory organ organization in Drosophila, we examined the role of ck/MyoVIIA in JO development and maintenance through confocal microscopy and extracellular electrophysiology. Here we show that ck/MyoVIIA is necessary early in the developing antenna for initial apical attachment of the scolopidia to the articulating joint. ck/MyoVIIA is also necessary to maintain scolopidial attachment throughout adulthood. Moreover, in the adult JO, ck/MyoVIIA genetically interacts with the non-muscle myosin II (through its regulatory light chain protein and the myosin binding subunit of myosin II phosphatase). Such genetic interactions have not previously been observed in scolopidia. These factors are therefore candidates for modulating MyoVIIA activity in vertebrates. Conclusions Our findings indicate that MyoVIIA plays evolutionarily conserved roles in auditory organ development and maintenance in invertebrates and vertebrates, enhancing our understanding of auditory organ development and function, as well as providing significant clues for future research.
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Affiliation(s)
- Sokol V. Todi
- Neuroscience Graduate Program, The University of Iowa, Iowa City, Iowa, United States of America
- Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America
| | - Elena Sivan-Loukianova
- Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America
| | - Julie S. Jacobs
- Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America
| | - Daniel P. Kiehart
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Daniel F. Eberl
- Neuroscience Graduate Program, The University of Iowa, Iowa City, Iowa, United States of America
- Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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33
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Yamashiro S, Yamakita Y, Totsukawa G, Goto H, Kaibuchi K, Ito M, Hartshorne DJ, Matsumura F. Myosin phosphatase-targeting subunit 1 regulates mitosis by antagonizing polo-like kinase 1. Dev Cell 2008; 14:787-97. [PMID: 18477460 PMCID: PMC2680213 DOI: 10.1016/j.devcel.2008.02.013] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2006] [Revised: 01/28/2008] [Accepted: 02/22/2008] [Indexed: 01/15/2023]
Abstract
Myosin phosphatase-targeting subunit 1 (MYPT1) binds to the catalytic subunit of protein phosphatase 1 (PP1C). This binding is believed to target PP1C to specific substrates including myosin II, thus controlling cellular contractility. Surprisingly, we found that during mitosis, mammalian MYPT1 binds to polo-like kinase 1 (PLK1). MYPT1 is phosphorylated during mitosis by proline-directed kinases including cdc2, which generates the binding motif for the polo box domain of PLK1. Depletion of PLK1 by small interfering RNAs is known to result in loss of gamma-tubulin recruitment to the centrosomes, blocking centrosome maturation and leading to mitotic arrest. We found that codepletion of MYPT1 and PLK1 reinstates gamma-tubulin at the centrosomes, rescuing the mitotic arrest. MYPT1 depletion increases phosphorylation of PLK1 at its activating site (Thr210) in vivo, explaining, at least in part, the rescue phenotype by codepletion. Taken together, our results identify a previously unrecognized role for MYPT1 in regulating mitosis by antagonizing PLK1.
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Affiliation(s)
- Shigeko Yamashiro
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ 08854, USA.
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Quintin S, Gally C, Labouesse M. Epithelial morphogenesis in embryos: asymmetries, motors and brakes. Trends Genet 2008; 24:221-30. [PMID: 18375008 DOI: 10.1016/j.tig.2008.02.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 01/30/2008] [Accepted: 02/01/2008] [Indexed: 10/22/2022]
Abstract
Epithelial cells play a central role in many embryonic morphogenetic processes, during which they undergo highly coordinated cell shape changes. Here, we review some common principles that have recently emerged through genetic and cellular analyses performed mainly with invertebrate genetic models, focusing on morphogenetic processes involving epithelial sheets. All available data argue that myosin II is the main motor that induces cell shape changes during morphogenesis. We discuss the control of myosin II activity during epithelial morphogenesis, as well as the recently described involvement of microtubules in this process. Finally, we examine how forces unleashed by myosin II can be measured, how embryos use specific brakes to control molecular motors and the potential input of mechano-sensation in morphogenesis.
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Affiliation(s)
- Sophie Quintin
- IGBMC, CNRS/INSERM/ULP, BP. 10142, 67404 Illkirch Cedex, France
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35
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Mulinari S, Barmchi MP, Häcker U. DRhoGEF2 and diaphanous regulate contractile force during segmental groove morphogenesis in the Drosophila embryo. Mol Biol Cell 2008; 19:1883-92. [PMID: 18287521 DOI: 10.1091/mbc.e07-12-1230] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Morphogenesis of the Drosophila embryo is associated with dynamic rearrangement of the actin cytoskeleton mediated by small GTPases of the Rho family. These GTPases act as molecular switches that are activated by guanine nucleotide exchange factors. One of these factors, DRhoGEF2, plays an important role in the constriction of actin filaments during pole cell formation, blastoderm cellularization, and invagination of the germ layers. Here, we show that DRhoGEF2 is equally important during morphogenesis of segmental grooves, which become apparent as tissue infoldings during mid-embryogenesis. Examination of DRhoGEF2-mutant embryos indicates a role for DRhoGEF2 in the control of cell shape changes during segmental groove morphogenesis. Overexpression of DRhoGEF2 in the ectoderm recruits myosin II to the cell cortex and induces cell contraction. At groove regression, DRhoGEF2 is enriched in cells posterior to the groove that undergo apical constriction, indicating that groove regression is an active process. We further show that the Formin Diaphanous is required for groove formation and strengthens cell junctions in the epidermis. Morphological analysis suggests that Dia regulates cell shape in a way distinct from DRhoGEF2. We propose that DRhoGEF2 acts through Rho1 to regulate acto-myosin constriction but not Diaphanous-mediated F-actin nucleation during segmental groove morphogenesis.
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Affiliation(s)
- Shai Mulinari
- Department of Experimental Medical Science, Lund Strategic Research Center for Stem Cell Biology and Cell Therapy, Lund University, 22184 Lund, Sweden
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Matsumura F, Hartshorne DJ. Myosin phosphatase target subunit: Many roles in cell function. Biochem Biophys Res Commun 2007; 369:149-56. [PMID: 18155661 DOI: 10.1016/j.bbrc.2007.12.090] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 12/11/2007] [Indexed: 12/12/2022]
Abstract
Phosphorylation of myosin II is important in many aspects of cell function and involves a myosin kinase, e.g. myosin light chain kinase, and a myosin phosphatase (MP). MP is regulated by the myosin phosphatase target subunit (MYPT1). The domain structure, properties, and genetic analyses of MYPT1 and its isoforms are outlined. MYPT1 binds the catalytic subunit of type 1 phosphatase, delta isoform, and also acts as an interactive platform for many other proteins. A key reaction for MP is with phosphorylated myosin II and the first process shown to be regulated by MP was contractile activity of smooth muscle. In cell division and cell migration myosin II phosphorylation also plays a critical role and these are discussed. However, based on the wide range of partners for MYPT1 it is likely that MP is implicated with substrates other than myosin II. Open questions are whether the diverse functions of MP reflect different cellular locations and/or specific roles for the MYPT1 isoforms.
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Affiliation(s)
- Fumio Matsumura
- Department of Molecular Biology and Biochemistry, Rutgers University, 604, Allison Road, Piscataway, NJ 08855, USA
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37
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Okamoto R, Ito M, Suzuki N, Kongo M, Moriki N, Saito H, Tsumura H, Imanaka-Yoshida K, Kimura K, Mizoguchi A, Hartshorne DJ, Nakano T. The targeted disruption of the MYPT1 gene results in embryonic lethality. Transgenic Res 2007; 14:337-40. [PMID: 16145842 DOI: 10.1007/s11248-005-3453-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Myosin phosphatase (MP) is a major phosphatase responsible for the dephosphorylation of the regulatory light chain of myosin II. MYPT1, a target subunit of smooth and nonmuscle MP, is responsible for activation and regulation of MP. To identity the physiological roles of MP, we have generated MYPT1-deficient mice by gene targeting. The heterozygous mice showed no changes in expression levels of MYPT1 and no distinct phenotype compared to wild-type mice was observed. None of the F2 mice were homozygous for the MYPT1 deletion, indicating that the targeted disruption of the MYPT1 gene resulted in embryonic lethality. The point of embryonic lethality is before 7.5 dpc. These findings indicate that MYPT1 is essential for mouse embryogenesis.
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Affiliation(s)
- Ryuji Okamoto
- The First Department of Internal Medicine, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan
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Fernández BG, Arias AM, Jacinto A. Dpp signalling orchestrates dorsal closure by regulating cell shape changes both in the amnioserosa and in the epidermis. Mech Dev 2007; 124:884-97. [PMID: 17950580 DOI: 10.1016/j.mod.2007.09.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 08/31/2007] [Accepted: 09/06/2007] [Indexed: 01/16/2023]
Abstract
During the final stages of embryogenesis, the Drosophila embryo exhibits a dorsal hole covered by a simple epithelium of large cells termed the amnioserosa (AS). Dorsal closure is the process whereby this hole is closed through the coordination of cellular activities within both the AS and the epidermis. Genetic analysis has shown that signalling through Jun N-terminal Kinase (JNK) and Decapentaplegic (Dpp), a Drosophila member of the BMP/TGF-beta family of secreted factors, controls these activities. JNK activates the expression of dpp in the dorsal-most epidermal cells, and subsequently Dpp acts as a secreted signal to control the elongation of lateral epidermis. Our analysis shows that Dpp function not only affects the epidermal cells, but also the AS. Embryos defective in Dpp signalling display defects in AS cell shape changes, specifically in the reduction of their apical surface areas, leading to defective AS contraction. Our data also demonstrate that Dpp regulates adhesion between epidermis and AS, and mediates expression of the transcription factor U-shaped in a gradient across both the AS and the epidermis. In summary, we show that Dpp plays a crucial role in coordinating the activity of the AS and its interactions with the LE cells during dorsal closure.
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Mitonaka T, Muramatsu Y, Sugiyama S, Mizuno T, Nishida Y. Essential roles of myosin phosphatase in the maintenance of epithelial cell integrity of Drosophila imaginal disc cells. Dev Biol 2007; 309:78-86. [PMID: 17662709 DOI: 10.1016/j.ydbio.2007.06.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 06/27/2007] [Accepted: 06/27/2007] [Indexed: 12/26/2022]
Abstract
Reorganization of the actin cytoskeleton and contraction of actomyosin play pivotal roles in controlling cell shape changes and motility in epithelial morphogenesis. Dephosphorylation of the myosin regulatory light chain (MRLC) by myosin phosphatase is one of the key events involved. Allelic combinations producing intermediate strength mutants of the Drosophila myosin-binding subunit (DMBS) of myosin phosphatase showed imaginal discs with multilayered disrupted morphologies, and extremely mislocated cells, suggesting that DMBS is required to maintain proper epithelial organization. Clonal analyses revealed that DMBS null mutant cells appear to retract basally and localization of apical junction markers such as DE-cadherin is indetectable in most cells, whereas phosphorylated MRLC and F-actin become heavily concentrated apically, indicating misconfiguration of the apical cytoskeleton. In agreement with these findings, DMBS was found to concentrate at the apical domain suggesting its function is localized. Phenotypes similar to DMBS mutants including increased migration of cells were obtained by overexpressing the constitutive active form of MRLC or Rho-associated kinase signifying that the phenotypes are indeed caused through activation of Myosin II. The requirement of DMBS for the integrity of static epithelial cells in imaginal discs suggests that the regulation of Myosin II by DMBS has a role more general than its previously demonstrated functions in morphogenetic events.
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Affiliation(s)
- Tomoaki Mitonaka
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
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40
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Fiehler RW, Wolff T. Drosophila Myosin II, Zipper, is essential for ommatidial rotation. Dev Biol 2007; 310:348-62. [PMID: 17826761 PMCID: PMC2110880 DOI: 10.1016/j.ydbio.2007.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 06/20/2007] [Accepted: 08/01/2007] [Indexed: 01/17/2023]
Abstract
The adult Drosophila retina is a highly polarized epithelium derived from a precursor tissue that is initially symmetric across its dorsoventral axis. Specialized 90 degrees rotational movements of subsets of cells, the ommatidial precursors, establish mirror symmetry in the retinal epithelium. Myosin II, or Zipper (Zip), a motor protein, regulates the rate at which ommatidia rotate: in zip mutants, the rate of rotation is significantly slowed. Zip is concentrated in the cells that we show to be at the likely interface between rotating and non-rotating cells: the boundary between differentiated and undifferentiated cells. Zip is also robust in newly added ommatidial cells, consistent with our model that the machinery that drives rotation should shift to newly recruited cells as they are added to the growing ommatidium. Finally, cell death genes and canonical Wnt signaling pathway members genetically modify the zip phenotype.
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Affiliation(s)
- Ryan W Fiehler
- Department of Genetics, Washington University School of Medicine, St Louis, MO 63110, USA
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Kirchner J, Gross S, Bennett D, Alphey L. The nonmuscle myosin phosphatase PP1beta (flapwing) negatively regulates Jun N-terminal kinase in wing imaginal discs of Drosophila. Genetics 2007; 175:1741-9. [PMID: 17277363 PMCID: PMC1855117 DOI: 10.1534/genetics.106.067488] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Drosophila flapwing (flw) codes for serine/threonine protein phosphatase type 1beta (PP1beta). Regulation of nonmuscle myosin activity is the single essential flw function that is nonredundant with the three closely related PP1alpha genes. Flw is thought to dephosphorylate the nonmuscle myosin regulatory light chain, Spaghetti Squash (Sqh); this inactivates the nonmuscle myosin heavy chain, Zipper (Zip). Thus, strong flw mutants lead to hyperphosphorylation of Sqh and hyperactivation of nonmuscle myosin activity. Here, we show genetically that a Jun N-terminal kinase (JNK) mutant suppresses the semilethality of a strong flw allele. Alleles of the JNK phosphatase puckered (puc) genetically enhance the weak allele flw1, leading to severe wing defects. Introducing a mutant of the nonmuscle myosin-binding subunit (Mbs) further enhances this genetic interaction to lethality. We show that puc expression is upregulated in wing imaginal discs mutant for flw1 and pucA251 and that this upregulation is modified by JNK and Zip. The level of phosphorylated (active) JNK is elevated in flw1 enhanced by puc. Together, we show that disruption of nonmuscle myosin activates JNK and puc expression in wing imaginal discs.
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Affiliation(s)
- Jasmin Kirchner
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
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42
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Watanabe T, Hosoya H, Yonemura S. Regulation of myosin II dynamics by phosphorylation and dephosphorylation of its light chain in epithelial cells. Mol Biol Cell 2006; 18:605-16. [PMID: 17151359 PMCID: PMC1783795 DOI: 10.1091/mbc.e06-07-0590] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Nonmuscle myosin II, an actin-based motor protein, plays an essential role in actin cytoskeleton organization and cellular motility. Although phosphorylation of its regulatory light chain (MRLC) is known to be involved in myosin II filament assembly and motor activity in vitro, it remains unclear exactly how MRLC phosphorylation regulates myosin II dynamics in vivo. We established clones of Madin Darby canine kidney II epithelial cells expressing MRLC-enhanced green fluorescent protein or its mutants. Time-lapse imaging revealed that both phosphorylation and dephosphorylation are required for proper dynamics of myosin II. Inhibitors affecting myosin phosphorylation and MRLC mutants indicated that monophosphorylation of MRLC is required and sufficient for maintenance of stress fibers. Diphosphorylated MRLC stabilized myosin II filaments and was distributed locally in regions of stress fibers where contraction occurs, suggesting that diphosphorylation is involved in the spatial regulation of myosin II assembly and contraction. We further found that myosin phosphatase or Zipper-interacting protein kinase localizes to stress fibers depending on the activity of myosin II ATPase.
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Affiliation(s)
- Toshiyuki Watanabe
- *RIKEN, Center for Developmental Biology, Kobe 650-0047, Japan
- Department of Life Science, Graduate School of Science and Technology, Kobe University, Kobe 657-8501, Japan; and
| | - Hiroshi Hosoya
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, 739-8526, Japan
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Franke JD, Montague RA, Kiehart DP. Nonmuscle myosin II generates forces that transmit tension and drive contraction in multiple tissues during dorsal closure. Curr Biol 2006; 15:2208-21. [PMID: 16360683 DOI: 10.1016/j.cub.2005.11.064] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Accepted: 11/16/2005] [Indexed: 11/16/2022]
Abstract
BACKGROUND The morphogenic movements that characterize embryonic development require the precise temporal and spatial control of cell-shape changes. Drosophila dorsal closure is a well-established model for epithelial sheet morphogenesis, and mutations in more than 60 genes cause defects in closure. Closure requires that four forces, derived from distinct tissues, be precisely balanced. The proteins responsible for generating each of the forces have not been determined. RESULTS We document dorsal closure in living embryos to show that mutations in nonmuscle myosin II (encoded by zipper; zip/MyoII) disrupt the integrity of multiple tissues during closure. We demonstrate that MyoII localization is distinct from, but overlaps, F-actin in the supracellular purse string, whereas in the amnioserosa and lateral epidermis each has similar, cortical distributions. In zip/MyoII mutant embryos, we restore MyoII function either ubiquitously or specifically in the leading edge, amnioserosa, or lateral epidermis and find that zip/MyoII function in any one tissue can rescue closure. Using a novel, transgenic mosaic approach, we establish that contractility of the supracellular purse string in leading-edge cells requires zip/MyoII-generated forces; that zip/MyoII function is responsible for the apical contraction of amnioserosa cells; that zip/MyoII is important for zipping; and that defects in zip/MyoII contractility cause the misalignment of the lateral-epidermal sheets during seam formation. CONCLUSIONS We establish that zip/MyoII is responsible for generating the forces that drive cell-shape changes in each of the force-generating tissues that contribute to closure. This highly conserved contractile protein likely drives cell-sheet movements throughout phylogeny.
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Affiliation(s)
- Josef D Franke
- Department of Biology, Developmental Cell and Molecular Biology Group, Duke University, Durham, North Carolina 27708, USA
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Lee JY, Marston DJ, Walston T, Hardin J, Halberstadt A, Goldstein B. Wnt/Frizzled signaling controls C. elegans gastrulation by activating actomyosin contractility. Curr Biol 2006; 16:1986-97. [PMID: 17055977 PMCID: PMC2989422 DOI: 10.1016/j.cub.2006.08.090] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 08/21/2006] [Accepted: 08/25/2006] [Indexed: 11/16/2022]
Abstract
BACKGROUND Embryonic patterning mechanisms regulate the cytoskeletal machinery that drives morphogenesis, but there are few cases where links between patterning mechanisms and morphogenesis are well understood. We have used a combination of genetics, in vivo imaging, and cell manipulations to identify such links in C. elegans gastrulation. Gastrulation in C. elegans begins with the internalization of endodermal precursor cells in a process that depends on apical constriction of ingressing cells. RESULTS We show that ingression of the endodermal precursor cells is regulated by pathways, including a Wnt-Frizzled signaling pathway, that specify endodermal cell fate. We find that Wnt signaling has a role in gastrulation in addition to its earlier roles in regulating endodermal cell fate and cell-cycle timing. In the absence of Wnt signaling, endodermal precursor cells polarize and enrich myosin II apically but fail to contract their apical surfaces. We show that a regulatory myosin light chain normally becomes phosphorylated on the apical side of ingressing cells at a conserved site that can lead to myosin-filament formation and contraction of actomyosin networks and that this phosphorylation depends on Wnt signaling. CONCLUSIONS We conclude that Wnt signaling regulates C. elegans gastrulation through regulatory myosin light-chain phosphorylation, which results in the contraction of the apical surface of ingressing cells. These findings forge new links between cell-fate specification and morphogenesis, and they represent a novel mechanism by which Wnt signaling can regulate morphogenesis.
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Affiliation(s)
- Jen-Yi Lee
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina 27599-3280, USA
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Bennett D, Lyulcheva E, Alphey L, Hawcroft G. Towards a comprehensive analysis of the protein phosphatase 1 interactome in Drosophila. J Mol Biol 2006; 364:196-212. [PMID: 17007873 DOI: 10.1016/j.jmb.2006.08.094] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 08/22/2006] [Accepted: 08/31/2006] [Indexed: 11/25/2022]
Abstract
Protein phosphatase type 1 (PP1) is one of the major classes of serine/threonine protein phosphatases, and has been found in all eukaryotic cells examined to date. Metazoans from Drosophila to humans have multiple genes encoding catalytic subunits of PP1 (PP1c), which are involved in a wide range of biological processes. Different PP1c isoforms have pleiotropic and overlapping functions; this has complicated the analysis of their biological roles and the identification of specific in vivo substrates. PP1c isoforms are associated in vivo with regulatory subunits that target them to specific locations and modify their substrate specificity and activity. The PP1c-binding proteins are therefore the key to understanding the role of PP1 in particular biological processes. The existence of isoform specific PP1c-binding subunits may also help to explain the unique roles of different PP1c isoforms. Here we report the identification of 24 genes encoding Drosophila PP1c-binding proteins in the yeast two-hybrid system. Sequence analysis identified a minimal interacting fragment and putative PP1c-binding motif for each protein, delimiting the region involved in binding to PP1c. Further two-hybrid analysis showed that virtually all of the interactors were capable of binding all Drosophila PP1c isoforms. One of the novel interactors, CG1553, was examined further and shown to interact with multiple isoforms by co-immunoprecipitation from Drosophila extracts and functional interaction with PP1c isoforms in vivo. Bioinformatic analyses implicate the putative PP1c-associated subunits in a diverse array of intracellular processes. Our identification of a large number of PP1c-binding proteins with the potential for directing PP1c's specific functions in Drosophila represents a significant step towards a full understanding of the range of PP1 complexes and function in animals.
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Affiliation(s)
- Daimark Bennett
- Department of Zoology, Oxford University, South Parks Road, Oxford, OX1 3PS, UK.
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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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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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48
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Thumkeo D, Shimizu Y, Sakamoto S, Yamada S, Narumiya S. ROCK-I and ROCK-II cooperatively regulate closure of eyelid and ventral body wall in mouse embryo. Genes Cells 2005; 10:825-34. [PMID: 16098146 DOI: 10.1111/j.1365-2443.2005.00882.x] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Rho-associated kinase (ROCK) is a serine/threonine kinase working in the Rho signaling to actin cytoskeleton. We previously reported that loss of ROCK-I results in the eyelid open at birth (EOB) and omphalocele phenotype in mice, while loss of ROCK-II results in placental dysfunction leading to intrauterine growth retardation and fetal death. Here, we report that after backcross to the C57BL/6 N genetic background, ROCK-II knockout (KO) neonates are born also with open eyelid and umbilical hernia, a phenotype similar to that of ROCK-I KO mice. ROCK-II KO embryos show impaired extension of the eyelid epithelial sheet with disorganized actin bundles in the leading edge of the sheet. These results suggest that ROCK-I and ROCK-II cooperatively regulates the assembly of actin bundles essential for closure of the eyelid and ventral body wall in mouse embryos. Consistently, ROCK-I(+/-)ROCK-II(+/-) double heterozygous mice also show the EOB and omphalocele phenotype.
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Affiliation(s)
- Dean Thumkeo
- Department of Pharmacology, Kyoto University Faculty of Medicine, Sakyo-ku, Kyoto 606-8501, Japan
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49
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Matsumura F. Regulation of myosin II during cytokinesis in higher eukaryotes. Trends Cell Biol 2005; 15:371-7. [PMID: 15935670 DOI: 10.1016/j.tcb.2005.05.004] [Citation(s) in RCA: 302] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Revised: 04/29/2005] [Accepted: 05/16/2005] [Indexed: 11/16/2022]
Abstract
Cellular myosin II is the principal motor responsible for cytokinesis. In higher eukaryotes, phosphorylation of the regulatory light chain (MLC) of myosin II is a primary means of activating myosin II and is known to be crucial for the execution of cell division. Because signals transmitted by the mitotic spindle coordinate key spatial and temporal aspects of cytokinesis, such signals should ultimately function to activate myosin II. Thus, it follows that identification of regulatory factors involved in MLC phosphorylation should elucidate the nature of spindle-derived regulatory signals and lead to a model for how they control cytokinesis. However, the identity of these upstream molecules remains elusive. This review (which is part of the Cytokinesis series) summarizes current views of the regulatory pathway controlling MLC phosphorylation and features four candidate molecules that are likely immediate upstream myosin regulators. I discuss proposed functions for MLCK, ROCK, citron kinase and myosin phosphatase during cytokinesis and consider the possibility of a link between these molecules and the signals transmitted by the mitotic spindle.
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Affiliation(s)
- Fumio Matsumura
- Department of Molecular Biology and Biochemistry, Rutgers University, 604 Allison Road, Piscataway, NJ 08855, USA.
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Shimizu Y, Thumkeo D, Keel J, Ishizaki T, Oshima H, Oshima M, Noda Y, Matsumura F, Taketo MM, Narumiya S. ROCK-I regulates closure of the eyelids and ventral body wall by inducing assembly of actomyosin bundles. ACTA ACUST UNITED AC 2005; 168:941-53. [PMID: 15753128 PMCID: PMC2171774 DOI: 10.1083/jcb.200411179] [Citation(s) in RCA: 256] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Rho-associated kinase (ROCK) I mediates signaling from Rho to the actin cytoskeleton. To investigate the in vivo functions of ROCK-I, we generated ROCK-I–deficient mice. Loss of ROCK-I resulted in failure of eyelid closure and closure of the ventral body wall, which gave rise to the eyes open at birth and omphalocele phenotypes in neonates. Most ROCK-I−/− mice died soon after birth as a result of cannibalization of the omphalocele by the mother. Actin cables that encircle the eye in the epithelial cells of the eyelid were disorganized and accumulation of filamentous actin at the umbilical ring was impaired, with loss of phosphorylation of the myosin regulatory light chain (MLC) at both sites, in ROCK-I−/− embryos. Stress fiber formation and MLC phosphorylation induced by EGF were also attenuated in primary keratinocytes from ROCK-I−/− mice. These results suggest that ROCK-I regulates closure of the eyelids and ventral body wall through organization of actomyosin bundles.
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Affiliation(s)
- Yoshihiko Shimizu
- Department of Pharmacology, Kyoto University Faculty of Medicine, Sakyo-ku, Kyoto 606-8501, Japan
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