title: Clathrin regulates centrosome positioning by promoting acto-myosin cortical tension in C. elegans embryos.
abstract: Regulation of centrosome and spindle positioning is crucial for spatial cell division control. The one-cell Caenorhabditis elegans embryo has proven attractive for dissecting the mechanisms underlying centrosome and spindle positioning in a metazoan organism. Previous work revealed that these processes rely on an evolutionarily conserved force generator complex located at the cell cortex. This complex anchors the motor protein dynein, thus allowing cortical pulling forces to be exerted on astral microtubules emanating from microtubule organizing centers (MTOCs). Here, we report that the clathrin heavy chain CHC-1 negatively regulates pulling forces acting on centrosomes during interphase and on spindle poles during mitosis in one-cell C. elegans embryos. We establish a similar role for the cytokinesis/apoptosis/RNA-binding protein CAR-1 and uncover that CAR-1 is needed to maintain proper levels of CHC-1. We demonstrate that CHC-1 is necessary for normal organization of the cortical acto-myosin network and for full cortical tension. Furthermore, we establish that the centrosome positioning phenotype of embryos depleted of CHC-1 is alleviated by stabilizing the acto-myosin network. Conversely, we demonstrate that slight perturbations of the acto-myosin network in otherwise wild-type embryos results in excess centrosome movements resembling those in chc-1(RNAi) embryos. We developed a 2D computational model to simulate cortical rigidity-dependent pulling forces, which recapitulates the experimental data and further demonstrates that excess centrosome movements are produced at medium cortical rigidity values. Overall, our findings lead us to propose that clathrin plays a critical role in centrosome positioning by promoting acto-myosin cortical tension.
authors: Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland.
authors: Zoltán
authors: Z
authors: Spiró
authors: Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland.
authors: Kalyani
authors: K
authors: Thyagarajan
authors: Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland.
authors: Alessandro
authors: A
authors: De Simone
authors: Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland.
authors: Sylvain
authors: S
authors: Träger
authors: Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland.
authors: Katayoun
authors: K
authors: Afshar
authors: Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL) Lausanne, Lausanne CH-1015, Switzerland pierre.gonczy@epfl.ch.
authors: Pierre
authors: P
authors: Gönczy
mesh_terms: D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D001696:Biomechanical Phenomena; D015153:Blotting, Western; D017173:Caenorhabditis elegans / Q000196:embryology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D018385:Centrosome / Q000378:metabolism*; D002966:Clathrin / Q000378:metabolism*; D004398:Dyneins / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D007091:Image Processing, Computer-Assisted; D007399:Interphase / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D008954:Models, Biological; D034622:RNA Interference; D016601:RNA-Binding Proteins / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; C506963:Car-1 protein, C elegans; D002966:Clathrin; D016601:RNA-Binding Proteins; D000205:Actomyosin; D004398:Dyneins
keywords: Centrosome positioning; Clathrin heavy chain; Cortical tension