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  • An actomyosin clamp assembled by the Amphiphysin-Rho1-Dia/DAAM-Rok pathway reinforces somatic cell membrane folded around spermatid heads.

An actomyosin clamp assembled by the Amphiphysin-Rho1-Dia/DAAM-Rok pathway reinforces somatic cell membrane folded around spermatid heads.

Cell reports (2021-04-01)
Tushna Kapoor, Pankaj Dubey, Seema Shirolikar, Krishanu Ray
ABSTRACT

Membrane curvature recruits Bin-Amphiphysin-Rvs (BAR)-domain proteins and induces local F-actin assembly, which further modifies the membrane curvature and dynamics. The downstream molecular pathway in vivo is still unclear. Here, we show that a tubular endomembrane scaffold supported by contractile actomyosin stabilizes the somatic cyst cell membrane folded around rigid spermatid heads during the final stages of sperm maturation in Drosophila testis. The structure resembles an actin "basket" covering the bundle of spermatid heads. Genetic analyses suggest that the actomyosin organization is nucleated exclusively by the formins - Diaphanous and Dishevelled Associated Activator of Morphogenesis (DAAM) - downstream of Rho1, which is recruited by the BAR-domain protein Amphiphysin. Actomyosin activity at the actin basket gathers the spermatid heads into a compact bundle and resists the somatic cell invasion by intruding spermatids. These observations reveal a distinct response mechanism of actin-membrane interactions, which generates a cell-adhesion-like strategy through active clamping.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Rho Kinase Inhibitor III, Rockout, The Rho Kinase Inhibitor III, Rockout, also referenced under CAS 7272-84-6, controls the biological activity of Rho Kinase. This small molecule/inhibitor is primarily used for Phosphorylation & Dephosphorylation applications.
Sigma-Aldrich
Poly-L-lysine solution, 0.1 % (w/v) in H2O
Sigma-Aldrich
Formin FH2 Domain Inhibitor, SMIFH2, The Formin FH2 Domain Inhibitor, SMIFH2, also referenced under CAS 340316-62-3, controls the biological activity of Formin FH2 Domain. This small molecule/inhibitor is primarily used for Membrane applications.