Unknown

Dataset Information

0

Neuronal nitric oxide synthase-induced S-nitrosylation of H-Ras inhibits calcium ionophore-mediated extracellular-signal-regulated kinase activity.


ABSTRACT: nNOS (neuronal nitric oxide synthase) is a constitutively expressed enzyme responsible for the production of NO* from L-arginine and O2. NO* acts as both an intra- and an inter-cellular messenger that mediates a variety of signalling pathways. Previous studies from our laboratory have demonstrated that nNOS production of NO* blocks Ca2+-ionophore-induced activation of ERK1/2 (extracellular-signal-regulated kinase 1/2) of the mitogen-activated protein kinases through a mechanism involving Ras G-proteins and Raf-1 kinase. Herein we describe a mechanism by which NO* blocks Ca2+-mediated ERK1/2 activity through direct modification of H-Ras. Ca2+-mediated ERK1/2 activation in NO*-producing cells could be restored by exogenous expression of constitutively active mitogen-activated protein kinase kinase 1. In contrast, exogenous expression of constitutively active mutants of Raf-1 and H-Ras only partially restored ERK1/2 activity, by 50% and 10% respectively. On the basis of these findings, we focused on NO*-mediated mechanisms of H-Ras inhibition. Assays for GTP loading and H-Ras interactions with the Ras-binding domain on Raf-1 demonstrated a decrease in H-Ras activity in the presence of NO*. We demonstrate that S-nitrosylation of H-Ras occurs in nNOS-expressing cells activated with Ca2+ ionophore. Mutation of a putative nitrosylation site at Cys118 inhibited S-nitrosylation and restored ERK1/2 activity by constitutively active H-Ras even in the presence of NO*. These findings indicate that intracellular generation of NO* by nNOS leads to S-nitrosylation of H-Ras, which interferes with Raf-1 activation and propagation of signalling through ERK1/2.

SUBMITTER: Raines KW 

PROVIDER: S-EPMC1513287 | biostudies-other | 2006 Jul

REPOSITORIES: biostudies-other

Similar Datasets

| S-EPMC6608267 | biostudies-literature
| S-EPMC2758698 | biostudies-literature
| S-EPMC4758687 | biostudies-literature
| S-EPMC6303682 | biostudies-literature
| S-EPMC1987713 | biostudies-literature
| S-EPMC1750883 | biostudies-other
| S-EPMC2001161 | biostudies-literature
| S-EPMC9271274 | biostudies-literature
2021-01-18 | GSE164521 | GEO
| S-EPMC3586978 | biostudies-literature