Cytoskeletal remodeling in differentiated vascular smooth muscle is actin isoform dependent and stimulus dependent.
Dynamic remodeling of the actin cytoskeleton plays an essential role in the migration and proliferation of vascular smooth muscle cells. It has been suggested that actin remodeling may also play an important functional role in nonmigrating, nonproliferating differentiated vascular smooth muscle (dVSM). In the present study, we show that contractile agonists increase the net polymerization of actin in dVSM, as measured by the differential ultracentrifugation of vascular smooth muscle tissue and the costaining of single freshly dissociated cells with fluorescent probes specific for globular and filamentous actin. Furthermore, induced alterations of the actin polymerization state, as well as actin decoy peptides, inhibit contractility in a stimulus-dependent manner. Latrunculin pretreatment or actin decoy peptides significantly inhibit contractility induced by a phorbol ester or an alpha-agonist, but these procedures have no effect on contractions induced by KCl. Aorta dVSM expresses alpha-smooth muscle actin, beta-actin, nonmuscle gamma-actin, and smooth muscle gamma-actin. The incorporation of isoform-specific cell-permeant synthetic actin decoy peptides, as well as isoform-specific probing of cell fractions and two-dimensional gels, demonstrates that actin remodeling during alpha-agonist contractions involves the remodeling of primarily gamma-actin and, to a lesser extent, beta-actin. Taken together, these results show that net isoform- and agonist-dependent increases in actin polymerization regulate vascular contractility.
Kim
Hak Rim
HR
Department of Health Sciences, Boston University, Boston, Massachusetts 02215, USA.
Gallant
Cynthia
C
Leavis
Paul C
PC
Gunst
Susan J
SJ
Morgan
Kathleen G
KG
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D047630:Depsipeptides / Q000494:pharmacology; D005289:Ferrets; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D010590:Phalloidine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D010703:Phorbol Esters / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D020033:Protein Isoforms; D014661:Vasoconstriction; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000199:Actins; D047630:Depsipeptides; D010446:Peptide Fragments; D010703:Phorbol Esters; D020033:Protein Isoforms; D014662:Vasoconstrictor Agents; C057531:jasplakinolide; D010590:Phalloidine; D010656:Phenylephrine; C047907:12-deoxyphorbol-13-isobutyrate-20-acetate; D011189:Potassium Chloride