Ngoc Chau
Cell Signalling Unit Children''s Medical Research Institute 214 Hawkesbury Road Westmead, NSW 2145, Australia Postal: Locked Bag 23, Wentworthville, NSW 2145, Australia

Abstract:

Dynamin I is a GTPase enzyme involved in synaptic vesicle endocytosis in neurons, which mediates endocytosis of activated receptors in most cells. Its GTPase activity is required for its function. We have been developing dynamin I inhibitors that block multiple forms of endocytosis. Dynasore is reported as a dynamin inhibitor (IC50 ~ 15 M) that blocks clathrin-mediated endocytosis. We show that for liposome-stimulated dynamin I GTPase activity dynasore is inactive with IC50 values of >M in the presence of tween-80 yet 9.4 μM in its absence. We300  designed and synthesised a focused set of dynasore analogues called dyngos. Dyngo-4a blocks liposome-stimulated dynamin I GTPase activity with nano-molar M) in the absence of tween-80. Its detergent sensitivitypotency (IC50 0.4  property was reduced 20-fold compared with dynasore. Dyngo-6a exhibited similar M), but was almost insensitive (1.7-fold) topotency to dynasore (IC50 3.2  tween-80. Dyngo-4a and -6a potently inhibited receptor-mediated endocytosis of M and blocked synaptictransferrin in U2OS cells with IC50 of 2.5 and 4.2  M,vesicle endocytosis in synaptosomes with IC50 of 16.4 and 43.7  respectively. Therefore, the dyngos are more potent dynamin inhibitors that are less sensitive to detergents and block multiple forms of endocytosis.