1. Ablation of SM22α decreases contractility and actin contents of mouse vascular smooth muscle
- Author
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Per Hellstrand, Karl Swärd, Eva Ekblad, Asad Zeidan, Michael S. Parmacek, Ina Nordström, and Janet C.L. Zhang
- Subjects
medicine.medical_specialty ,Vascular smooth muscle ,Calponin ,Biophysics ,Muscle Proteins ,Alpha (ethology) ,Adrenergic ,Mice, Inbred Strains ,macromolecular substances ,Biochemistry ,Muscle, Smooth, Vascular ,Contractility ,Mice ,Structural Biology ,Receptors, Adrenergic, alpha-1 ,Internal medicine ,Genetics ,Protein biosynthesis ,medicine ,Animals ,Protein Isoforms ,Receptor ,Molecular Biology ,Actin ,Mice, Knockout ,biology ,Stretch ,Microfilament Proteins ,Cell Biology ,Actins ,Cell biology ,Resistance artery ,Endocrinology ,Differentiation ,Portal vein ,biology.protein ,Blood Vessels ,Adrenergic alpha-Agonists ,Muscle Contraction - Abstract
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.
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