Role of Protein Kinase Cζ and Calcium Entry in KCl-Induced Vascular Smooth Muscle Calcium Sensitization and Feedback Control of Cellular Calcium Levels
- 14 November 2008
- journal article
- Published by American Society for Pharmacology & Experimental Therapeutics (ASPET) in Journal of Pharmacology and Experimental Therapeutics
- Vol. 328 (2), 399-408
- https://doi.org/10.1124/jpet.108.142422
Abstract
The degree of tonic force (F) maintenance induced in vascular smooth muscle upon K+ depolarization with 110 mM KCl can be greatly reduced by inhibition of rhoA kinase (ROCK). We explored the possibility that a protein kinase C (PKC) isotype may also play a role in causing KCl-induced Ca2+ sensitization. In isometric rings of rabbit artery, the PKC inhibitors, Go-6983 (3-[1-[3-(dimethylamino)propyl]-5-methoxy-1H-indol-3-yl]-4-(1H-indol-3-yl)-1H-pyrrole-2,5-dione), GF-109203X (2-[1-(3-dimethylaminopropyl)indol-3-yl]-3-(indol-3-yl) maleimide), and a cell-permeable (myristoylated) pseudosubstrate inhibitor of PKCζ (PIPKCζ) inhibited KCl-induced tonic F. A myristoylated pseudosubstrate inhibitor of PKCα/β that inhibited phorbol dibutyrate-induced F slightly potentiated KCl-induced tonic F and attenuated 30 mM KCl-induced F. Although the ROCK inhibitor, H-1152 [(S)-(+)-2-methyl-1-[(4-methyl-5-isoquinolinyl)-sulfonyl]-hexahydro-1H-1,4-diazepine dihydrochloride], reduced basal phosphorylation of myosin light-chain phosphatase-targeting subunit at Thr853 (MYPT1-pT853), 3 and 10 μM GF-109203X inhibited only KCl-stimulated phosphorylation, not basal MYPT1-pT853. In fura-2-loaded tissues, GF-109203X and PIPKCζ elevated basal [Ca2+]i (calcium) and potentiated KCl-induced tonic increases in calcium while reducing KCl-induced tonic increases in F. Blockade by nifedipine of Ca2+ entry through voltage-operated Ca2+ channels reduced KCl-induced Ca2+ sensitization and KCl-stimulated but not basal MYPT1-pT853. These data together support a model in which ROCK and PKCζ are constitutively active and function in “resting” muscle to regulate the basal levels of MYPT1-pT853 and calcium, respectively. In this model, KCl-induced increases in calcium activate PKCζ to feed forward and cause additional MYPT1-pT853 above that induced by constitutive ROCK, permitting Ca2+ sensitization and strong F maintenance. Active PKCζ also feeds back to attenuate the degree of KCl-induced increases in calcium.Keywords
This publication has 44 references indexed in Scilit:
- Development of Rho-kinase inhibitors for cardiovascular medicineTrends in Pharmacological Sciences, 2007
- Ca 2+ -Dependent Rapid Ca 2+ Sensitization of Contraction in Arterial Smooth MuscleCirculation Research, 2007
- Phosphorylation of Thr695 and Thr850 on the myosin phosphatase target subunit: Inhibitory effects and occurrence in A7r5 cellsFEBS Letters, 2005
- Dedicated Myosin Light Chain Kinases with Diverse Cellular FunctionsJournal of Biological Chemistry, 2001
- Specificity and mechanism of action of some commonly used protein kinase inhibitorsBiochemical Journal, 2000
- Agonists Trigger G Protein-mediated Activation of the CPI-17 Inhibitor Phosphoprotein of Myosin Light Chain Phosphatase to Enhance Vascular Smooth Muscle ContractilityJournal of Biological Chemistry, 2000
- Inhibition of protein kinase C μ by various inhibitors. Inhibition from protein kinase c isoenzymesFEBS Letters, 1996
- Pharmacology of Protein Kinase InhibitorsAnnual Review of Pharmacology and Toxicology, 1992
- Ca2+ localization and sensitivity in vascular smooth muscleTrends in Pharmacological Sciences, 1989
- Norepinephrine and GTP-γ-S increase myofilament Ca2+ sensitivity in α-toxin permeabilized arterial smooth muscleBiochemical and Biophysical Research Communications, 1988