Structured RhoGEF recruitment drives myosin II organization on large exocytotic vesicles

Kumari Kamalesh; Dagan Segal; Ori Avinoam; Eyal D. Schejter; Ben-Zion Shilo

doi:10.1101/2023.09.06.556511

Structured RhoGEF recruitment drives myosin II organization on large exocytotic vesicles

Kumari Kamalesh, Dagan Segal, Ori Avinoam^*, Eyal D. Schejter^*, Ben-Zion Shilo^*

^*Corresponding author for this work

Research output: Contribution to journal › Article

Abstract

he Rho family of GTPases plays a crucial role in cellular mechanics, by regulating actomyosin contractility through the parallel induction of actin and myosin assembly and function. Using exocytosis of large vesicles in the Drosophila larval salivary gland as a model, we followed the spatiotemporal regulation of Rho1, that in turn creates distinct organization patterns of actin and myosin. After vesicle fusion, low levels of activated Rho1 diffuse to the vesicle membrane and drive actin nucleation in an uneven, spread-out pattern. Subsequently, the Rho1 activator RhoGEF2 distributes as an irregular meshwork on the vesicle membrane, activating Rho1 in a corresponding punctate pattern and driving local myosin II recruitment, resulting in vesicle constriction. Vesicle membrane buckling and subsequent crumpling occur at local sites of high myosin II concentrations. These findings indicate that distinct thresholds for activated Rho1 create a biphasic mode of actomyosin assembly, inducing anisotropic membrane crumpling during exocrine secretion.

Original language	Undefined/Unknown
Journal	BioRxiv
DOIs	https://doi.org/10.1101/2023.09.06.556511
Publication status	In preparation - 6 Sept 2023

Funding

We thank Dr. R’ada Massarwa and Vandana Bharadia for help at the initial stages of this work. The research was supported by Israel Science Foundation (grant no. 706/20) to B.-Z.S., O.A., and E.D.S. and the Minerva Foundation with funding from the Federal German Ministry for Education and Research. O.A. also acknowledges funding from the Henry Chanoch Krenter Institute for Biomedical Imaging and Genomics, the Schwartz Reisman Collaborative Science Program, the Yeda-Sela Center for Basic Research, and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no 851080). O.A. is an incumbent of the Miriam Berman presidential development chair. B.-Z.S. is an incumbent of the Hilda and Cecil Lewis Professorial Chair in Molecular Genetics. This paper is dedicated to the memory of the late Dr. R’ada Massarwa, a groundbreaking scientist with an unlimited passion to visualize and uncover the wonders of Biology.

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10.1101/2023.09.06.556511Licence: CC BY-ND

Cite this

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title = "Structured RhoGEF recruitment drives myosin II organization on large exocytotic vesicles",

abstract = "he Rho family of GTPases plays a crucial role in cellular mechanics, by regulating actomyosin contractility through the parallel induction of actin and myosin assembly and function. Using exocytosis of large vesicles in the Drosophila larval salivary gland as a model, we followed the spatiotemporal regulation of Rho1, that in turn creates distinct organization patterns of actin and myosin. After vesicle fusion, low levels of activated Rho1 diffuse to the vesicle membrane and drive actin nucleation in an uneven, spread-out pattern. Subsequently, the Rho1 activator RhoGEF2 distributes as an irregular meshwork on the vesicle membrane, activating Rho1 in a corresponding punctate pattern and driving local myosin II recruitment, resulting in vesicle constriction. Vesicle membrane buckling and subsequent crumpling occur at local sites of high myosin II concentrations. These findings indicate that distinct thresholds for activated Rho1 create a biphasic mode of actomyosin assembly, inducing anisotropic membrane crumpling during exocrine secretion.",

author = "Kumari Kamalesh and Dagan Segal and Ori Avinoam and Schejter, \{Eyal D.\} and Ben-Zion Shilo",

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AU - Segal, Dagan

AU - Avinoam, Ori

AU - Schejter, Eyal D.

AU - Shilo, Ben-Zion

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N2 - he Rho family of GTPases plays a crucial role in cellular mechanics, by regulating actomyosin contractility through the parallel induction of actin and myosin assembly and function. Using exocytosis of large vesicles in the Drosophila larval salivary gland as a model, we followed the spatiotemporal regulation of Rho1, that in turn creates distinct organization patterns of actin and myosin. After vesicle fusion, low levels of activated Rho1 diffuse to the vesicle membrane and drive actin nucleation in an uneven, spread-out pattern. Subsequently, the Rho1 activator RhoGEF2 distributes as an irregular meshwork on the vesicle membrane, activating Rho1 in a corresponding punctate pattern and driving local myosin II recruitment, resulting in vesicle constriction. Vesicle membrane buckling and subsequent crumpling occur at local sites of high myosin II concentrations. These findings indicate that distinct thresholds for activated Rho1 create a biphasic mode of actomyosin assembly, inducing anisotropic membrane crumpling during exocrine secretion.

AB - he Rho family of GTPases plays a crucial role in cellular mechanics, by regulating actomyosin contractility through the parallel induction of actin and myosin assembly and function. Using exocytosis of large vesicles in the Drosophila larval salivary gland as a model, we followed the spatiotemporal regulation of Rho1, that in turn creates distinct organization patterns of actin and myosin. After vesicle fusion, low levels of activated Rho1 diffuse to the vesicle membrane and drive actin nucleation in an uneven, spread-out pattern. Subsequently, the Rho1 activator RhoGEF2 distributes as an irregular meshwork on the vesicle membrane, activating Rho1 in a corresponding punctate pattern and driving local myosin II recruitment, resulting in vesicle constriction. Vesicle membrane buckling and subsequent crumpling occur at local sites of high myosin II concentrations. These findings indicate that distinct thresholds for activated Rho1 create a biphasic mode of actomyosin assembly, inducing anisotropic membrane crumpling during exocrine secretion.

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