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J R Molinaro

Publications and source records attributed to J R Molinaro.

5 recordsLinked to original sources
PubMed2001

PI3-kinase/Akt modulates vascular smooth muscle tone via cAMP signaling pathways.

Phosphatidylinositol 3-kinase (PI3-kinase) activates protein kinase B (also known as Akt), which phosphorylates and activates a cyclic nucleotide phosphodiesterase 3B. Increases in cyclic nucleotide concentrations inhibit agonist-induced contraction of vascular smooth muscle. Thus we hypothesized that the PI3-kinase/Akt pathway may regulate vascular smooth muscle tone. In unstimulated, intact bovine carotid artery smooth muscle, the basal phosphorylation of Akt was higher than that in cultured smooth muscle cells. The phosphorylation of Akt decreases in a time-dependent manner when incubated with the PI3-kinase inhibitor, LY-294002. Agonist (serotonin)-, phorbol ester (phorbol 12,13-dibutyrate; PDBu)-, and depolarization (KCl)-induced contractions of vascular smooth muscles were all inhibited in a dose-dependent fashion by LY-294002. However, LY-294002 did not inhibit serotonin- or PDBu-induced increases in myosin light chain phosphorylation or total O(2) consumption, suggesting that inhibition of contraction was not mediated by reversal or inhibition of the pathways that lead to smooth muscle activation and contraction. Treatment of vascular smooth muscle with LY-294002 increased the activity of cAMP-dependent protein kinase and increased the phosphorylation of the cAMP-dependent protein kinase substrate heat shock protein 20 (HSP20). These data suggest that activation of the PI3-kinase/Akt pathway in unstimulated smooth muscle may modulate vascular smooth muscle tone (allow agonist-induced contraction) through inhibition of the cyclic nucleotide/HSP20 pathway and suggest that cyclic nucleotide-dependent inhibition of contraction is dissociated from the myosin light chain contractile regulatory pathways.

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PubMed2000

The macromolecular associations of heat shock protein-27 in vascular smooth muscle.

BACKGROUND: Behavioral stress is a risk factor for hypertension and atherosclerosis. Stress leads to increases in the expression and phosphorylation of heat shock proteins (HSPs) in vascular smooth muscle. Two small heat shock proteins, HSP27 and HSP20, have been implicated in the regulation of the contraction and relaxation of smooth muscle. We hypothesized that stress-induced alterations in the phosphorylation of HSP27 would effect the macromolecular associations of the small HSPs. METHODS: Bovine carotid artery smooth muscle was treated with buffer alone or with the chemical stressor, arsenite. HSP27 phosphorylation was determined with isoelectric focusing immunoblotting. Macromolecular interactions were determined with subcellular fractionation, molecular sieving, and glutaraldehyde cross-linking and immunoblotting. RESULTS: Arsenite treatment led to increases in the phosphorylation of HSP27, a redistribution of some HSP27 from a cytosolic to a particulate fraction and to the formation of larger macromolecular aggregates of HSP27. Glutaraldehyde cross-linking and immunoblotting demonstrated that HSP27 existed in monomeric and dimeric forms, which suggested that the large aggregates were not simply aggregates of HSP27 but contained other proteins. CONCLUSIONS: Cellular stress leads to increases in the phosphorylation of HSP27 and to changes in the macromolecular associations of HSP27 in intact vascular smooth muscles. The functions of the small HSPs in the vascular smooth muscle may be dependent on both phosphorylation and macromolecular associations.

Animals↗