Ablation of SM22alpha decreases contractility and actin contents of mouse vascular smooth muscle.
The actin-binding protein SM22alpha marks contractile differentiation in smooth muscle, but its function is unknown. We tested its role in arterial contractility and stretch-sensitive vascular protein synthesis. Active stress in depolarised mesenteric resistance arteries and portal veins was reduced by 40% in SM22alpha(-/-) mice. Passive and active arterial circumference-force relationships were shifted leftwards, whereas alpha(1)-adrenergic responses were increased. Actin contents were 10-25% lower in vessels from SM22alpha(-/-) mice, but protein composition was otherwise similar. Synthesis of SM22alpha, calponin and alpha-actin, but not beta-actin, was sensitive to stretch. Ablation of SM22alpha did not affect stretch sensitivity of any of these proteins. Thus, SM22alpha plays a role in contractility, possibly by affecting actin filament organisation.
Zeidan
Asad
A
Department of Physiological Sciences, Lund University, Biomedical Centre, BMC F12, SE-221 84 Lund, Sweden.
Swärd
Karl
K
Nordström
Ina
I
Ekblad
Eva
E
Zhang
Janet C L
JC
Parmacek
Michael S
MS
Hellstrand
Per
P
D000199:Actins / Q000378:metabolism*; D000316:Adrenergic alpha-Agonists / Q000378:metabolism; D000818:Animals; D001808:Blood Vessels / Q000033:anatomy & histology / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D009119:Muscle Contraction / Q000502:physiology*; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D020033:Protein Isoforms / Q000378:metabolism; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism
D000199:Actins; D000316:Adrenergic alpha-Agonists; D008840:Microfilament Proteins; D009124:Muscle Proteins; D020033:Protein Isoforms; D018340:Receptors, Adrenergic, alpha-1; C058992:Tagln protein, mouse; C051615:transgelin