title: Myosin light chain kinase controls voltage-dependent calcium channels in vascular smooth muscle.
abstract: The Ca(2+)-dependent kinase myosin light chain kinase (MLCK) is the activator of smooth muscle contraction. In addition, it has been reported to be involved in Ca(2+) channel regulation in cultured cells, and we previously showed that the MLCK inhibitor ML-7 decreases arginine vasopressin (AVP)-induced Ca(2+) influx in rat aorta. This study was designed to investigate whether MLCK is involved in Ca(2+) regulation in resistance artery smooth muscle cell, which plays a major role in the control of blood pressure. As ML compounds were shown to have off-target effects, MLCK was downregulated by transfection with a small interfering RNA targeting MLCK (MLCK-siRNA) in rat small resistance mesenteric artery (RMA) and in the rat embryonic aortic cell line A7r5. Noradrenaline-induced contraction and Ca(2+) signal were significantly depressed in MLCK-siRNA compared to scramble-siRNA-transfected RMA. Contraction and Ca(2+) signal induced by high KCl and voltage-activated Ca(2+) current were also significantly decreased in MLCK-siRNA-transfected RMA, suggesting that MLCK depletion modifies voltage-operated Ca(2+) channels. KCl- and AVP-induced Ca(2+) signals and voltage-activated Ca(2+) current were decreased in MLCK-depleted A7r5 cells. Eventually, real-time quantitative PCR analysis indicated that in A7r5, MLCK controlled mRNA expression of CaV1.2 (L-type) and CaV3.1 (T-type) voltage-dependent Ca(2+) channels. Our results suggest that MLCK controls the transcription of voltage-dependent Ca(2+) channels in vascular smooth muscle cells.
authors.affiliation: Laboratoire de Physiologie Cellulaire, IoNS, Université Catholique de Louvain (B1 5512), Avenue Hippocrate 55, 1200, Brussels, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Martinsen
authors.forename: O
authors.initials: O
authors.lastname: Schakman
authors.forename: X
authors.initials: X
authors.lastname: Yerna
authors.forename: C
authors.initials: C
authors.lastname: Dessy
authors.forename: N
authors.initials: N
authors.lastname: Morel
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000378:metabolism*; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D008297:Male; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014661:Vasoconstriction
chemical_list: D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D012333:RNA, Messenger; D001127:Arginine Vasopressin; D011189:Potassium Chloride; D009219:Myosin-Light-Chain Kinase; D002118:Calcium; D009638:Norepinephrine