Spatiotemporal recruitment of RhoGTPase protein GRAF inhibits actomyosin ring constriction in Drosophila cellularization

  1. Swati Sharma
  2. Richa Rikhy  Is a corresponding author
  1. Indian Institute of Science Education and Research Pune, India


Actomyosin contractility is regulated by Rho-GTP in cell migration, cytokinesis and morphogenesis in embryo development. Whereas Rho activation by Rho-GTP exchange factor (GEF), RhoGEF2 is well known in actomyosin contractility during cytokinesis at the base of invaginating membranes in Drosophila cellularization, Rho inhibition by RhoGTPase activating proteins (GAP) remains to be studied. We have found that the RhoGAP, GRAF inhibits actomyosin contractility during cellularization. GRAF is enriched at the cleavage furrow tip during actomyosin assembly and initiation of ring constriction. Graf depletion shows increased Rho-GTP, increased Myosin II and ring hyper constriction dependent upon the loss of the RhoGTPase domain. GRAF and RhoGEF2 are present in a balance for appropriate activation of actomyosin ring constriction. RhoGEF2 depletion and abrogation of Myosin II activation in Rho Kinase mutants suppresses the Graf hyper constriction defect. Therefore, GRAF recruitment restricts Rho-GTP levels in a spatiotemporal manner for inhibiting actomyosin contractility during cellularization.

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The data generated and analysed during this study are included in the source data files.

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Author details

  1. Swati Sharma

    Biology, Indian Institute of Science Education and Research Pune, Pune, India
    Competing interests
    The authors declare that no competing interests exist.
  2. Richa Rikhy

    Biology, Indian Institute of Science Education and Research Pune, Pune, India
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4262-0238


Department of Biotechnology, India (BT/PR26071/GET/119/108/2017)

  • Richa Rikhy

Council of Scientific and Industrial Research, India (Graduate fellowship)

  • Swati Sharma

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Derek Applewhite, Reed College, United States

Publication history

  1. Received: September 28, 2020
  2. Accepted: March 31, 2021
  3. Accepted Manuscript published: April 9, 2021 (version 1)
  4. Version of Record published: April 28, 2021 (version 2)


© 2021, Sharma & Rikhy

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.


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  1. Swati Sharma
  2. Richa Rikhy
Spatiotemporal recruitment of RhoGTPase protein GRAF inhibits actomyosin ring constriction in Drosophila cellularization
eLife 10:e63535.

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