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Negative regulation of rho signaling by insulin and its impact on actin cytoskeleton organization in vascular smooth muscle cells: role of nitric oxide and cyclic guanosine monophosphate signaling pathways.
Diabetes. 2002 Jul; 51(7):2256-63.D

Abstract

Recent studies from our laboratory have shown that insulin induces relaxation of vascular smooth muscle cells (VSMCs) via stimulation of myosin phosphatase and inhibition of Rho kinase activity. In this study, we examined the mechanism whereby insulin inhibits Rho signaling and its impact on actin cytoskeleton organization. Incubation of confluent serum-starved VSMCs with thrombin or phenylephrine (PE) caused a rapid increase in glutathione S-transferase-Rhotekin-Rho binding domain-associated RhoA, Rho kinase activation, and actin cytoskeleton organization, which was blocked by preincubation with insulin. Preexposure to N(G)-monomethyl L-arginine acetate (L-NMMA), a nitric oxide synthase inhibitor, and Rp-8 CPT-cyclic guanosine monophosphate (RpcGMP), a cyclic guanosine monophosphate (cGMP) antagonist, attenuated the inhibitory effect of insulin on RhoA activation and restored thrombin-induced Rho kinase activation, and site-specific phosphorylation of the myosin-bound regulatory subunit (MBS(Thr695)) of myosin-bound phosphatase (MBP), and caused actin fiber reorganization. In contrast, 8-bromo-cGMP, a cGMP agonist, mimicked the inhibitory effects of insulin and abolished thrombin-mediated Rho activation. Insulin inactivation of RhoA was accompanied by inhibition of isoprenylation via reductions in geranylgeranyl transferase-1 activity as well as increased RhoA phosphorylation, which was reversed by pretreatment with RpcGMP and L-NMMA. We conclude that insulin may inhibit Rho signaling by affecting posttranslational modification of RhoA via nitric oxide/cGMP signaling pathway to cause MBP activation, actin cytoskeletal disorganization, and vasodilation.

Authors+Show Affiliations

Diabetes Research Laboratory, Winthrop University Hospital, 259 First Street, Mineola, NY 11501, USA. nbegum@winthrop.orgNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

12086958

Citation

Begum, Najma, et al. "Negative Regulation of Rho Signaling By Insulin and Its Impact On Actin Cytoskeleton Organization in Vascular Smooth Muscle Cells: Role of Nitric Oxide and Cyclic Guanosine Monophosphate Signaling Pathways." Diabetes, vol. 51, no. 7, 2002, pp. 2256-63.
Begum N, Sandu OA, Duddy N. Negative regulation of rho signaling by insulin and its impact on actin cytoskeleton organization in vascular smooth muscle cells: role of nitric oxide and cyclic guanosine monophosphate signaling pathways. Diabetes. 2002;51(7):2256-63.
Begum, N., Sandu, O. A., & Duddy, N. (2002). Negative regulation of rho signaling by insulin and its impact on actin cytoskeleton organization in vascular smooth muscle cells: role of nitric oxide and cyclic guanosine monophosphate signaling pathways. Diabetes, 51(7), 2256-63.
Begum N, Sandu OA, Duddy N. Negative Regulation of Rho Signaling By Insulin and Its Impact On Actin Cytoskeleton Organization in Vascular Smooth Muscle Cells: Role of Nitric Oxide and Cyclic Guanosine Monophosphate Signaling Pathways. Diabetes. 2002;51(7):2256-63. PubMed PMID: 12086958.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Negative regulation of rho signaling by insulin and its impact on actin cytoskeleton organization in vascular smooth muscle cells: role of nitric oxide and cyclic guanosine monophosphate signaling pathways. AU - Begum,Najma, AU - Sandu,Oana A, AU - Duddy,Noreen, PY - 2002/6/28/pubmed PY - 2002/7/27/medline PY - 2002/6/28/entrez SP - 2256 EP - 63 JF - Diabetes JO - Diabetes VL - 51 IS - 7 N2 - Recent studies from our laboratory have shown that insulin induces relaxation of vascular smooth muscle cells (VSMCs) via stimulation of myosin phosphatase and inhibition of Rho kinase activity. In this study, we examined the mechanism whereby insulin inhibits Rho signaling and its impact on actin cytoskeleton organization. Incubation of confluent serum-starved VSMCs with thrombin or phenylephrine (PE) caused a rapid increase in glutathione S-transferase-Rhotekin-Rho binding domain-associated RhoA, Rho kinase activation, and actin cytoskeleton organization, which was blocked by preincubation with insulin. Preexposure to N(G)-monomethyl L-arginine acetate (L-NMMA), a nitric oxide synthase inhibitor, and Rp-8 CPT-cyclic guanosine monophosphate (RpcGMP), a cyclic guanosine monophosphate (cGMP) antagonist, attenuated the inhibitory effect of insulin on RhoA activation and restored thrombin-induced Rho kinase activation, and site-specific phosphorylation of the myosin-bound regulatory subunit (MBS(Thr695)) of myosin-bound phosphatase (MBP), and caused actin fiber reorganization. In contrast, 8-bromo-cGMP, a cGMP agonist, mimicked the inhibitory effects of insulin and abolished thrombin-mediated Rho activation. Insulin inactivation of RhoA was accompanied by inhibition of isoprenylation via reductions in geranylgeranyl transferase-1 activity as well as increased RhoA phosphorylation, which was reversed by pretreatment with RpcGMP and L-NMMA. We conclude that insulin may inhibit Rho signaling by affecting posttranslational modification of RhoA via nitric oxide/cGMP signaling pathway to cause MBP activation, actin cytoskeletal disorganization, and vasodilation. SN - 0012-1797 UR - https://www.unboundmedicine.com/medline/citation/12086958/Negative_regulation_of_rho_signaling_by_insulin_and_its_impact_on_actin_cytoskeleton_organization_in_vascular_smooth_muscle_cells:_role_of_nitric_oxide_and_cyclic_guanosine_monophosphate_signaling_pathways_ L2 - http://diabetes.diabetesjournals.org/cgi/pmidlookup?view=long&pmid=12086958 DB - PRIME DP - Unbound Medicine ER -