Change in RhoGAP and RhoGEF availability drives transitions in cortical patterning and excitability in Drosophila

Jonathan A Jackson; Marlis Denk-Lobnig; Katherine A Kitzinger; Adam C Martin

doi:10.1016/j.cub.2024.04.021

Change in RhoGAP and RhoGEF availability drives transitions in cortical patterning and excitability in Drosophila

Curr Biol. 2024 Apr 21:S0960-9822(24)00461-5. doi: 10.1016/j.cub.2024.04.021. Online ahead of print.

Authors

Jonathan A Jackson¹, Marlis Denk-Lobnig², Katherine A Kitzinger³, Adam C Martin⁴

Affiliations

¹ Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA; Graduate Program in Biophysics, Harvard University, 86 Brattle Street, Cambridge, MA 02138, USA.
² Department of Biophysics, University of Michigan, 1109 Geddes Ave., Ann Arbor, MI 48109, USA.
³ Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA.
⁴ Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA. Electronic address: acmartin@mit.edu.

PMID: 38688282
DOI: 10.1016/j.cub.2024.04.021

Abstract

Actin cortex patterning and dynamics are critical for cell shape changes. These dynamics undergo transitions during development, often accompanying changes in collective cell behavior. Although mechanisms have been established for individual cells' dynamic behaviors, the mechanisms and specific molecules that result in developmental transitions in vivo are still poorly understood. Here, we took advantage of two developmental systems in Drosophila melanogaster to identify conditions that altered cortical patterning and dynamics. We identified a Rho guanine nucleotide exchange factor (RhoGEF) and Rho GTPase activating protein (RhoGAP) pair required for actomyosin waves in egg chambers. Specifically, depletion of the RhoGEF, Ect2, or the RhoGAP, RhoGAP15B, disrupted actomyosin wave induction, and both proteins relocalized from the nucleus to the cortex preceding wave formation. Furthermore, we found that overexpression of a different RhoGEF and RhoGAP pair, RhoGEF2 and Cumberland GAP (C-GAP), resulted in actomyosin waves in the early embryo, during which RhoA activation precedes actomyosin assembly by ∼4 s. We found that C-GAP was recruited to actomyosin waves, and disrupting F-actin polymerization altered the spatial organization of both RhoA signaling and the cytoskeleton in waves. In addition, disrupting F-actin dynamics increased wave period and width, consistent with a possible role for F-actin in promoting delayed negative feedback. Overall, we showed a mechanism involved in inducing actomyosin waves that is essential for oocyte development and is general to other cell types, such as epithelial and syncytial cells.

Keywords: Drosophila egg chamber; Drosophila embryo; RhoA; actomyosin cortex; development; excitability.