Dynamin-2 Phosphorylation as A Critical Regulatory Target of Bin1 and GSK3α for Endocytosis in Muscle

Abstract

Tight regulation of endocytosis ensures accurate control of cellular signaling and membrane dynamics, which are crucial for tissue morphogenesis and functions. Mutations of Bin1 and dynamin-2 (Dyn2), proteins that generate membrane curvature and sever endocytic invaginations, respectively, cause progressive hereditary myopathy. Here, we show that Bin1 inhibits Dyn2 via direct interaction of its SRC Homology 3 (SH3) domain with the proline-rich domain (PRD) of Dyn2. Phosphorylation of S848 of Dyn2 by GSK3α, a kinase downstream of insulin signaling, relieves Dyn2 from the inhibition of Bin1 and promotes endocytosis in muscle. Mutations of Bin1 associated with centronuclear myopathy disrupt its inhibition of Dyn2, thereby exaggerating Dyn2 fission activity and causing excessive fragmentation of T-tubules in the muscle cells. Our work reveals how Bin1-Dyn2 interaction fine-tunes membrane remodeling at the molecular level, and lay the foundation for future exploration of endocytic regulation and hereditary muscle diseases.

Lithium-induced ciliary lengthening sparks Arp2/3 complex-dependent endocytosis

“…GSK has been previously shown to target the dynamin protein family; in neuronal and non-neuronal mammalian cells dynamin 1 is usually inactive due to phosphorylation by GSK3ß, but when cells are treated with CHIR99021 to inhibit GSK3, dynamin 1 is dephosphorylated and endocytosis rates increase significantly (Srinivasan et al 2018; Smillie and Cousin 2012). Meanwhile, GSK3α has been found to phosphorylate mammalian Dynamin 2 (Laiman et al 2021).…”

The host GTPase Dynamin 2 modulates apical junction structure to control cell-to-cell spread ofListeria monocytogenes

“…The amino-terminus of Tuba contains four tandem SH3 domains that directly interact with the mammalian GTPase Dynamin 1 (17). Dynamin 1 is the founding member of a GTPase family that also includes Dynamin 2 and Dynamin 3 (18,19). Whereas Dynamin 1 and Dynamin 3 are expressed mainly in the brain, expression of Dynamin 2 is ubiquitous.…”

“…The three Dynamin GTPases each have important roles in clathrin-mediated endocytosis (CME), albeit in different cell types (18)(19)(20). Dynamin 1 and Dynamin 3 promote endocytosis and recycling of synaptic vesicles in presynaptic neurons, while Dynamin 2 mediates CME in non-neuronal cells (20)(21)(22).…”

“…Dynamin 2 also contributes to endocytic pathways that are independent of clathrin, including caveolin-mediated endocytosis, micropinocytosis, and internalization of select cytokine receptors (23)(24)(25). The three Dynamin proteins exhibit GTPdependent membrane fission activity, which is critical for their endocytic roles (19). In addition to stimulating membrane fission, Dynamin proteins use their GTPase activity to regulate the actin cytoskeleton (18,26,27).…”

“…The three Dynamin proteins share a common structure that includes an aminoterminal domain with GTPase activity, a central 'stalk' region containing a four-helix bundle, and a carboxyl-terminal proline and arginine-rich domain (PRD) (19). Dynamin GTPases are recruited to the plasma membrane by interaction of their PRD with SH3 domains in various proteins that contain BAR (Bin-Amphiphysin-Rvs) domains (39,40).…”