CYK-1/Formin activation in cortical RhoA signaling centers promotes organismal left–right symmetry breaking
Abstract
Proper left–right symmetry breaking is essential for animal development, and in many cases, this process is actomyosin-dependent. In Caenorhabditis elegans embryos active torque generation in the actomyosin layer promotes left–right symmetry breaking by driving chiral counterrotating cortical flows. While both Formins and Myosins have been implicated in left–right symmetry breaking and both can rotate actin filaments in vitro, it remains unclear whether 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 counterrotation and dispensable for chiral symmetry breaking of cortical flows. Instead, we find that CYK-1/Formin activation in RhoA foci is instructive for chiral counterrotation 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.
Additional Information
© 2021 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND). Edited by Timothy J. Mitchison, Harvard Medical School, Boston, MA, and approved March 15, 2021 (received for review October 21, 2020). We thank Julie Canman for sharing cyk-1(or596ts); Bob Goldstein for nmy-2(cp8[nmy-2::GFP]) and nmy-2(cp52[nmy-2::mKate2); Tony Hyman for the mCherry-tubulin strain and mlc-4 and ect-2 RNAi clones; Martin Harterink and Sander van den Heuvel for PH-GFP-LOV2 plasmid; the Caenorhabditis Genetics Center for the ect-2(gf) mutant and xsSi5[GFP-ani-1(AH-PH)]; Addgene for pJA281, pJA245, pCM1.36, pCFJ150, and pCFJ1415 plasmids; and Julie Ahringer and Source BioScience for 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 2018 Woods Hole Physiology course, and Sylvia Hurlimann for capturing SIM-TIRF movies during this course. Furthermore, we thank Jonas Neipel for valuable discussion on the hydrodynamic theory and Anne Grapin-Botton, Arghyadip Mukherjee, Ján Sabó, Jonas Neipel, and Zdeněk Lánský for critical reading of the manuscript. T.C.M. was supported by a European Molecular Biology Organization long-term fellowship ALTF 1033-2015 and a Nederlandse organisatie voor Wetenschappelijk Onderzoek Rubicon fellowship 825.15.010. L.G.P. was supported by the European Union's Horizon 2020 research under the Marie Sklodowska-Curie Grant 641639. S.W.G. was supported by the Deutsche Forschungsgemeinschaft (SPP 1782, GSC 97, GR 3271/2, GR 3271/3, GR 3271/4) and the European Research Council (Grant 742712). Data Availability: The raw data generated in this study is made publicly available: Speckle microscopy movies can be downloaded from CaltechDATA at https://data.caltech.edu/records/1442 (81). All other movies and micrographs can be downloaded from the Max Planck Society at https://dx.doi.org/10.17617/3.61 (82). J.G.-B. and P.Q.-C. contributed equally to this work. Author contributions: T.C.M. and S.W.G. designed research; T.C.M., J.G.-B., P.Q.-C., L.G.P., and S.Y. performed research; T.C.M., J.G.-B., P.Q.-C., and P.G. contributed new reagents/analytic tools; T.C.M., J.G.-B., P.Q.-C., L.G.P., P.W.S., P.G., and S.W.G. analyzed data; and T.C.M. and S.W.G. wrote the paper. The authors declare no competing interest. This article is a PNAS Direct Submission. This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2021814118/-/DCSupplemental.Attached Files
Published - e2021814118.full.pdf
Submitted - 2021.01.08.425924v1.full.pdf
Supplemental Material - pnas.2021814118.sapp.pdf
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Additional details
- PMCID
- PMC8157923
- Eprint ID
- 107396
- Resolver ID
- CaltechAUTHORS:20210111-143923766
- European Molecular Biology Organization (EMBO)
- ALTF 1033-2015
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
- 825.15.010
- Marie Curie Fellowship
- 641639
- 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
- Created
-
2021-01-11Created from EPrint's datestamp field
- Updated
-
2021-06-01Created from EPrint's last_modified field
- Caltech groups
- Division of Biology and Biological Engineering (BBE)