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CYK-1/Formin activation in cortical RhoA signaling centers promotes organismal left-right symmetry breaking

Middelkoop, Teije C. and Garcia-Baucells, Júlia and Quintero-Cadena, Porfirio and Pimpale, Lokesh G. and Yazdi, Shahrzad and Sternberg, Paul and Gross, Peter and Grill, Stephan W. (2021) CYK-1/Formin activation in cortical RhoA signaling centers promotes organismal left-right symmetry breaking. . (Unpublished)

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Proper left-right symmetry breaking is essential for animal development and in many species the actin cytoskeleton plays an instrumental role in this process. Active torque generation in the actomyosin layer promotes left-right symmetry breaking in C. elegans embryos by driving chiral counter-rotating cortical flows. While both Formins and Myosins have been implied in left-right symmetry breaking, and both can rotate actin filaments in vitro, it remains unclear if active torques in the actomyosin cortex are generated by Formins, Myosins, or both. We combined the strength of C. elegans genetics with quantitative imaging and thin film, chiral active fluid theory to show that, while Non-Muscle Myosin II activity drives cortical actomyosin flows, it is permissive for chiral counter-rotation and dispensable for chiral symmetry breaking of cortical flows. Instead, we find that CYK-1/Formin activation in RhoA foci is instructive for chiral counter-rotation and promotes in-plane, active torque generation in the actomyosin cortex. Notably, we observe that artificially generated large active RhoA patches undergo rotations with consistent handedness in a CYK-1/Formin-dependent manner. Altogether, we conclude that, CYK-1/Formin-dependent active torque generation facilitates chiral symmetry breaking of actomyosin flows and drives organismal left-right symmetry breaking in the nematode worm. Significance: Active torque generation in the actin cytoskeleton has been implicated in driving left-right symmetry breaking of developing embryos, but which molecules generate the active torque and how active torque generation is organized subcellularly remains unclear. This study shows that cortical Formin, recruited to cortical regions where RhoA signaling is active, promotes active torque generation in the actomyosin layer. We find that active torque tends to locally rotate the cortex in a clockwise fashion, which drives the emergence of chiral counter-rotating flows with consistent handedness and facilitates left-right symmetry breaking of C. elegans embryos.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper
Middelkoop, Teije C.0000-0002-0346-6143
Quintero-Cadena, Porfirio0000-0003-0067-5844
Pimpale, Lokesh G.0000-0001-6145-1516
Sternberg, Paul0000-0002-7699-0173
Grill, Stephan W.0000-0002-2290-5826
Additional Information:The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. This version posted January 8, 2021. We thank Julie Canman for sharing the cyk-1(or596ts) mutant, Bob Goldstein for sharing nmy-2(cp8[nmy-2::GFP]) and nmy-2(nmy-2(cp52[nmy-2::mKate2), Tony Hyman for sharing the mCherry-tubulin strain, mlc-4 and ect-2 RNAi clones, Martin Harterink and Sander van den Heuvel for sharing the PH-GFP-LOV2 plasmid, the CGC for providing the ect-2(gf) mutant and xsSi5[GFP-ani-1(AH-PH)], Addgene for the pJA281, pJA245, pCM1.36, pCFJ150, pCFJ1415 plasmids, Julie Ahringer and Source BioScience for providing the L4440, rga-3 and cyk-1/Formin RNAi clones. We also thank Friederike Thonwart for assistance with molecular biology, GE-Deltavision and its representatives for having the Deltavision OMX SIM-TIRF system available for the Woods Hole physiology course 2018 and thank Sylvia Hurlimann for capturing the SIM-TIRF movies during this course. Furthermore, we thank Jonas Neipel for valuable discussion on the hydrodynamic theory. We thank Anne Grapin-Botton, Arghyadip Mukherjee, Ján Sabó, Jonas Neipel and Zdenek Lánsky for critical reading of the manuscript. Author Contributions: T.C.M. and S.W.G. conceptualized the work, analyzed the data and wrote the manuscript together. T.C.M. performed and analyzed the experiments and applied chiral active fluid theory. J.B.G. performed and analyzed the compression experiments with help from T.C.M and P.G. P.Q.C. performed the co -localization analysis, performed the speckle microscopy experiments, and extracted and analyzed the speckle microscopy data with help of P.S.. L.P. performed and analyzed the cell division skew experiments with help from T.C.M. S.Y. helped with the hyperchirality rescue experiments. T.C.M was supported by the European Molecular Biology Organization (EMBO) long-term fellowship ALTF 1033-2015, and by the Dutch Research Council (NWO) Rubicon fellowship 825.15.010. L.P. was supported by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 641639. S.W.G was supported by the DFG (SPP 1782, GSC 97, GR 3271/2, GR 3271/3, GR 3271/4) and the European Research Council (grant 742712). The authors declare that they have no competing financial interests.
Funding AgencyGrant Number
European Molecular Biology Organization (EMBO)ALTF 1033-2015
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)825.15.010
Marie Curie Fellowship641639
Deutsche Forschungsgemeinschaft (DFG)SPP 1782
Deutsche Forschungsgemeinschaft (DFG)GSC 97
Deutsche Forschungsgemeinschaft (DFG)GR 3271/2
Deutsche Forschungsgemeinschaft (DFG)GR 3271/3
Deutsche Forschungsgemeinschaft (DFG)GR 3271/4
European Research Council (ERC)742712
Record Number:CaltechAUTHORS:20210111-143923766
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Official Citation:CYK-1/Formin activation in cortical RhoA signaling centers promotes organismal left-right symmetry breaking. Teije C. Middelkoop, Júlia Garcia-Baucells, Porfirio Quintero-Cadena, Lokesh G. Pimpale, Shahrzad Yazdi, Paul Sternberg, Peter Gross, Stephan W. Grill. bioRxiv 2021.01.08.425924; doi:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107396
Deposited By: Tony Diaz
Deposited On:11 Jan 2021 23:02
Last Modified:11 Jan 2021 23:02

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