title: Active torque generation by the actomyosin cell cortex drives left-right symmetry breaking.
abstract: Many developmental processes break left-right (LR) symmetry with a consistent handedness. LR asymmetry emerges early in development, and in many species the primary determinant of this asymmetry has been linked to the cytoskeleton. However, the nature of the underlying chirally asymmetric cytoskeletal processes has remained elusive. In this study, we combine thin-film active chiral fluid theory with experimental analysis of the C. elegans embryo to show that the actomyosin cortex generates active chiral torques to facilitate chiral symmetry breaking. Active torques drive chiral counter-rotating cortical flow in the zygote, depend on myosin activity, and can be altered through mild changes in Rho signaling. Notably, they also execute the chiral skew event at the 4-cell stage to establish the C. elegans LR body axis. Taken together, our results uncover a novel, large-scale physical activity of the actomyosin cytoskeleton that provides a fundamental mechanism for chiral morphogenesis in development.
authors.affiliation: Biotechnology Center, Technical University Dresden, Dresden, Germany.
authors.forename: Sundar Ram
authors.initials: SR
authors.lastname: Naganathan
authors.affiliation: Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fürthauer
authors.affiliation: Biotechnology Center, Technical University Dresden, Dresden, Germany.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nishikawa
authors.affiliation: Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Jülicher
authors.affiliation: Biotechnology Center, Technical University Dresden, Dresden, Germany.
authors.forename: Stephan W
authors.initials: SW
authors.lastname: Grill
mesh_terms: D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D019521:Body Patterning; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000196:embryology* / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D015398:Signal Transduction; D019415:Torque; D051153:Wnt Proteins / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D051153:Wnt Proteins; D000205:Actomyosin; D009218:Myosins; D020741:rho GTP-Binding Proteins
keywords: C. elegans; L/R symmetry breaking; Wnt signaling; active torques; actomyosin cortex; biophysics; hydrodynamics; structural biology