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Related Experiment Video

Updated: Jun 23, 2025

Author Spotlight: Optogenetic Inhibition of Rho1-Mediated Actomyosin Contractility Coupled with Measurement of Epithelial Tension in Drosophila Embryos
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Structured RhoGEF recruitment drives myosin II organization on large exocytic vesicles.

Kumari Kamalesh1,2, Dagan Segal1, Ori Avinoam2

  • 1Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.

Journal of Cell Science
|June 20, 2024
PubMed
Summary

Rho GTPases regulate cellular mechanics. This study reveals how Rho1 and RhoGEF2 orchestrate actin and myosin assembly for vesicle constriction and membrane crumpling during Drosophila exocrine secretion.

Keywords:
DrosophilaActomyosinExocrine secretionRhoRhoGEFSalivary gland

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Last Updated: Jun 23, 2025

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Area of Science:

  • Cell Biology
  • Biophysics
  • Molecular Biology

Background:

  • Rho family GTPases are key regulators of cellular mechanics.
  • Actomyosin contractility is essential for various cellular processes, including membrane dynamics.
  • Exocytosis involves complex membrane remodeling events.

Purpose of the Study:

  • To investigate the spatiotemporal regulation of Rho1 during exocytosis.
  • To elucidate the role of Rho1 and its activator RhoGEF2 in actomyosin assembly and vesicle constriction.
  • To understand the mechanisms underlying membrane buckling and crumpling during secretion.

Main Methods:

  • Utilized the Drosophila larval salivary gland exocytosis model.
  • Tracked the localization and activation patterns of Rho1 and RhoGEF2.
  • Observed actin and myosin II dynamics using live imaging.
  • Analyzed vesicle membrane deformation and structural changes.

Main Results:

  • Activated Rho1 initially nucleates actin in a spread-out pattern post-vesicle fusion.
  • RhoGEF2 forms an irregular meshwork, leading to punctate Rho1 activation and local myosin II recruitment.
  • High myosin II concentrations induce local vesicle membrane buckling and crumpling.
  • Distinct Rho1 activation thresholds result in biphasic actomyosin assembly.

Conclusions:

  • Rho1 spatiotemporal regulation dictates anisotropic actomyosin assembly.
  • This process drives localized membrane deformation, leading to vesicle crumpling during exocrine secretion.
  • Findings provide insights into the mechanical regulation of membrane dynamics in secretion.