Protein kinase C enhances myosin light-chain kinase effects on force development and ATPase activity in rat single skinned cardiac cells.
Many neurohormones alter the force of cardiac contraction by variations in the intracellular Ca2+ concentration. alpha 1-Adrenergic and muscarinic stimulations, rather, modify the sensitivity of contractile proteins to Ca(2+)-calmodulin-myosin light-chain kinase (MLCK) complex induces a large increase in Ca2+ sensitivity (0.14 pCa unit) of these easily accessible myofilaments. This increase is further enhanced by up to 0.19 pCa unit when protein kinase C (PKC) is added together with MLCK. Similarly, the Ca2+ ATPase activity of skinned cells in suspension is increased in the presence of MLCK and further in the presence of both kinases. 32P-labelling and SDS/PAGE show that these changes are associated with light-chain 2 (LC2) phosphorylation together with phosphorylation of troponin I and troponin T when PKC is added. Although to a smaller extent than in smooth muscle, phosphorylation of cardiac myosin LC2 may be involved in the modulation of heart contractility.
Clement
O
O
Unité de Recherches de Physiologie Cellulaire Cardiaque, INSERM U-241, Université Paris-Sud, Orsay, France.
Puceat
M
M
Walsh
M P
MP
Vassort
G
G
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D003285:Contractile Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D014336:Troponin / Q000378:metabolism
D003285:Contractile Proteins; D014336:Troponin; D011493:Protein Kinase C; D009219:Myosin-Light-Chain Kinase; D000251:Adenosine Triphosphatases; D009218:Myosins