Live-Cell Imaging in Caenorhabditis elegans Reveals the Distinct Roles of Dynamin Self-Assembly and Guanosine Triphosphate Hydrolysis in the Removal of Apoptotic Cells

Abstract

During cell corpse removal, dynamin's self-assembly and GTP hydrolysis activities establish a precise dynamic control of DYN-1's transient association to its target membranes. Dynamin's dynamic membrane association controls the mechanism that underlies the recruitment of downstream effectors, such as small GTPases RAB-5 and RAB-7, to target membranes.

Stalk Domain of the Dynamin-like MxA GTPase Protein Mediates Membrane Binding and Liposome Tubulation via the Unstructured L4 Loop

“…Surprisingly, the assembly of MxA onto liposomes did not change GTP hydrolysis whereas liposome binding of dynamin increased nucleotide hydrolysis about 20-fold, as expected (Fig. 4) (26,28,42). Intracellular membranes are the active sites of dynamin action.…”

“…Both MxA and dynamin form tetramers in solution with a low basal rate of nucleotide hydrolysis (8,18) and are known to form higher order oligomers at elevated protein concentrations as well as on lipid membranes (16, 19 -22). Self-assembly leads to increased GTP hydrolysis rates (8,18,23,24), and interaction of dynamin with lipid bilayers via its PH domain further enhances assembly-stimulated GTP hydrolysis (25)(26)(27)(28). To investigate the function of lipid interaction for MxA and identify the region responsible for membrane binding, we performed a detailed study of the membrane binding properties of MxA using biochemical assays as well as cryo-transmission electron microscopy (cryo-TEM).…”

Programmed Cell Death DuringCaenorhabditis elegansDevelopment

“…Membrane-bound, GTP-bound Rab proteins act as tethering factors to promote organelle-organelle or organellemembrane fusion. RAB-5 is detected on the phagosomal membrane once the nascent phagosome is formed during cell corpse clearance (He et al 2010). The recruitment of RAB-5 and its effector VPS-34 to phagosomes is mutually dependent and DYN-1-dependent, suggesting a model in which DYN-1 acts upstream of RAB-5 and VPS-34, while RAB-5 and VPS-34 may act as a positive feedback system ( Figure 4A) (Kinchen et al 2008;He et al 2009).…”

Nucleoside diphosphate kinases (NDPKs) in animal development

“…2b). Detailed studies on dyn-1 revealed its function in both steps of apoptotic cell removal [121,122]. During the engulfment phase, DYN-1 ensures the rapid expansion of phagocyte membrane along the surface of dying cells by organizing vesicle transport and promoting fusion of early endosomes to extending pseudopods [121,122] (Fig.…”

“…2b). Recruitment of two endosomal markers, RAB-5 and RAB-7, also relies on DYN-1 activity [122][123][124]. RAB-5 is important for promoting the maturation of phagosomes containing apoptotic cells [124,125].…”