Protein kinase A-dependent phosphorylation of ryanodine receptors increases Ca2+ leak in mouse heart.
In heart failure, chronic catecholaminergic stimulation increases diastolic Ca(2+) leak from ryanodine receptors (RyRs) of sarcoplasmic reticulum (SR), possibly due to the phosphorylation of RyRs through the activation of protein kinase A (PKA) or Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). In the present study, we attempted to identify which activated kinase is responsible for the enhanced Ca(2+) leak caused by beta-adrenergic stimulation. Trabeculae obtained from the hearts of adult male C57BL/6J mice were treated with isoproterenol and then permeabilized with saponin. To examine SR functions, Ca(2+) in SR was released with caffeine and measured with fluo-3. The Ca(2+) leak in isoproterenol-treated preparations was significantly increased when the PKA-dependent phosphorylation of RyR was increased without the involvement of CaMKII-dependent phosphorylation. Both the increase in Ca(2+) leak and the phosphorylation of RyR were blocked by a PKA inhibitor. Our results show that beta-adrenergic stimulation increases Ca(2+) leak from SR through PKA-dependent phosphorylation of RyR.
Department of Cell Physiology, The Jikei University School of Medicine, Tokyo 105-8461, Japan.
Satoshi
S
Morimoto
Jin
J
O-Uchi
Makoto
M
Kawai
Toshiyuki
T
Hoshina
Yoichiro
Y
Kusakari
Kimiaki
K
Komukai
Hiroyuki
H
Sasaki
Kenichi
K
Hongo
Satoshi
S
Kurihara
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D051379:Mice; D009206:Myocardium / Q000378:metabolism*; D010766:Phosphorylation; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D012503:Saponins / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*
D000318:Adrenergic beta-Agonists; D011943:Receptors, Adrenergic, beta; D019837:Ryanodine Receptor Calcium Release Channel; D012503:Saponins; D017868:Cyclic AMP-Dependent Protein Kinases; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D007545:Isoproterenol; D002118:Calcium