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Oana A. Sandu, Najma Begum, P-420: Negative regulation of Rho signaling by insulin: Role of nitric oxide/cGMP signaling pathways, American Journal of Hypertension, Volume 14, Issue S1, April 2001, Page 171A, https://doi.org/10.1016/S0895-7061(01)01578-3
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Abstract
Recent studies from this laboratory have shown that insulin rapidly inhibits thrombin-mediated Rho kinase activation and decreases myosin light chain (MLC20) phosphorylation and contraction in cultured primary vascular smooth muscle cells (VSMCs) by activating myosin-bound phosphatase(MBP). Because Rho kinase is one of the downstream targets of RhoA, we examined the effect of insulin on thrombin-mediated RhoA activation and its translocation to membrane fraction under the conditions where signaling via nitric oxide and cGMP pathways is prevented by pretreatment with L-NMMA (a nitric oxide synthase inhibitor) and RpcGMP (a cGMP antagonist) respectively. Incubation of confluent serum starved VSMCs with thrombin (1 U/ml)for 5 min caused a 2-3 fold increase in the content of RhoA in the membrane fraction which was blocked by preincubating VSMCs with 100 nM insulin for 10 min. In contrast, insulin failed to inhibit thrombin-mediated RhoA translocation in VSMCs isolated from spontaneous hypertensive rats. In control VSMCs, pretreatment with L-NMMA (1 mM)and RpcGMP (10 uM)for 60 min attenuated insulin's inhibitory effect on thrombin-mediated RhoA translocation and Rho kinase activation. In contrast, sodium nitroprusside (a nitric oxide donor) as well as 8-bromo-cGMP, a cGMP agonist mimicked insulin's inhibitory effects and prevented thrombin-mediated RhoA translocation. Furthermore, insulin caused a 2-fold increase in phosphorylation of RhoA which was blocked by Wortmaninn, a PI3-kinase inhibitor, L-NMMA, RpcGMP and 10 uM ODQ, a selective inhibitor of guanylate cyclase. Collectively, these results indicate that insulin phosphorylates and negatively modulates RhoA signaling via the PI3-kinase/NO/cGMP pathway to promote vosodilation by activating MBP which dephosphorylates MLC20.
- nitric oxide
- hypertension
- signal transduction
- myosins
- cyclic gmp
- muscle, smooth, vascular
- 1-phosphatidylinositol 3-kinase
- guanylate cyclase
- mechlorethamine
- tissue membrane
- myosin light chains
- new mexico
- omega-n-methylarginine
- phosphoric monoester hydrolases
- phosphorylation
- phosphotransferases
- rhoa gtp-binding protein
- translocation (genetics)
- insulin
- rats
- thrombin
- nitroprusside sodium
- agonists
- antagonists
- signal pathway
- nitric oxide synthase inhibitors
- signal transduction pathways
- attenuation
- current good manufacturing practice
- donors
