Previous Article | Next Article ![]()
Mol. Cell. Biol., Sep 1996, 5069-5080, Vol 16, No. 9
R Kozma, S Ahmed, A Best and L Lim
n-Chimaerin is a GTPase-activating protein (GAP) mainly for Rac1 and less
so for Cdc42Hs in vitro. The GAP activity of n-chimaerin is regulated by
phospholipids and phorbol esters. Microinjection of Rac1 and Cdc42Hs into
mammalian cells induces formation of the actin-based structures
lamellipodia and filopodia, respectively, with the former being prevented
by coinjection of the chimaerin GAP domain. Strikingly, microinjection of
the full-length n-chimaerin into fibroblasts and neuroblastoma cells
induces the simultaneous formation of lamellipodia and filopodia. These
structures undergo cycles of dissolution and formation, resembling natural
morphological events occurring at the leading edge of fibroblasts and
neuronal growth cones. The effects of n- chimaerin on formation of
lamellipodia and filopodia were inhibited by dominant negative Rac1(T17N)
and Cdc42Hs(T17N), respectively. n- Chimaerin's effects were also inhibited
by coinjection with Rho GDP dissociation inhibitor or by treatment with
phorbol ester. A mutant n- chimaerin with no GAP activity and impaired p21
binding was ineffective in inducing morphological changes, while a mutant
lacking GAP activity alone was effective. Microinjected n-chimaerin
colocalized in situ with F-actin. Taken together, these results suggest
that n-chimaerin acts synergistically with Rac1 and Cdc42Hs to induce
actin-based morphological changes and that this action involves Rac1 and
Cdc42Hs binding but not GAP activity. Thus, GAPs may have morphological
functions in addition to downregulation of GTPases.
Copyright © 1996, American Society for Microbiology
The GTPase-activating protein n-chimaerin cooperates with Rac1 and Cdc42Hs to induce the formation of lamellipodia and filopodia
Department of Neurochemistry, Institute of Neurology, London, United Kingdom.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»