Facilitation of Ca2+‐dependent exocytosis by Rac1‐GTPase in bovine chromaffin cells

• DOI: 10.1113/jphysiol.2003.039073
• Publication Date: 2003-05-20T01:48:20Z
• Authors: Quanwen Li; Chi S. Ho; Vlad Marinescu; Humaa Bhatti; Gary M. Bokoch; Stephen A. Ernst; Ronald W. Holz; Edward L. Stuenkel
• Keywords: PAK1; Rac GTP-Binding Proteins

Rho family GTPases are primary mediators of cytoskeletal reorganization, although they have also been reported to regulate cell secretion. Yet, the extent which activated by secretory stimuli in neural and neuroendocrine cells remains unknown. In bovine adrenal chromaffin cells, we found Rac1, but not Cdc42, be rapidly selectively using an assay selective for GTPases. To examine effects Rac1 on secretion, constitutively active mutants (Rac1‐V12, Rac1‐L61) were transiently expressed cells. These facilitated responses elicited from populations intact digitonin‐permeabilized as well under whole patch clamp. A dominant negative mutant (Rac1‐N17) produced no effect Expression RhoGDI, a regulator inhibited while overexpression effectors notably, p21‐activated kinase (Pak1) actin depolymerization factor (ADF) promoted evoked addition, expression effector domain Rac1‐V12 that exhibit reduced activation regulators Pak1 Partner (POR1) resulted loss Rac1‐V12‐mediated enhancement findings suggest part, functions modulate secretion through actions cytoskeleton. Consistent with this hypothesis, modifying drugs phalloidin jasplakinolide enhanced latrunculin‐A eliminated Rac1‐V12. summary, was modulated pathway downstream Ca 2+ influx, partly regulation organization.