CaMKII is responsible for activity-dependent acceleration of relaxation in rat ventricular myocytes

1995 ◽  
Vol 268 (2) ◽  
pp. H703-H712 ◽  
Author(s):  
R. A. Bassani ◽  
A. Mattiazzi ◽  
D. M. Bers
Keyword(s):  
Protein Kinase ◽  
Ventricular Myocytes ◽  
Protein Kinase Inhibitors ◽  
Mechanical Relaxation ◽  
Dependent Protein Kinase ◽  
Rat Ventricular Myocytes ◽  
Ca Uptake ◽  
Dependent Protein ◽  
Rat Myocytes ◽  
Activity Dependent

We investigated the role of Ca/calmodulin-dependent protein kinase (CaMKII) in relaxation and cytosolic free [Ca] ([Ca]i) decline during steady-state (SS) and postrest (PR) twitches in intact rat ventricular myocytes. Half-time of mechanical relaxation and time constant of [Ca]i decline (tau) were twofold greater during PR than with SS at 1 Hz. This difference was 1) abolished by inhibition of sarcoplasmic reticulum (SR) Ca accumulation by thapsigargin or caffeine; 2) greater at higher stimulation frequency and extracellular [Ca], which affected only SS tau; 3) abolished by the protein phosphatase inhibitor okadaic acid (10 microM, which selectively accelerated [Ca]i decline during PR); 4) still present during stimulation or inhibition of adenosine 3',5'-cyclic monophosphate-dependent protein kinase (PKA) by 10 microM forskolin or 1 microM H-89, respectively (SS and PR tau values were abbreviated and prolonged, respectively); and 5) suppressed by 10 microM KN-62, a selective inhibitor of CaMKII, which selectively prolonged [Ca]i decline during SS twitches. Both protein kinase inhibitors were also shown to decrease the SR Ca-uptake rate in digitonin-permeabilized rat myocytes. We conclude that CaMKII plays a major role in modulation of relaxation in rat ventricular myocytes, enhancing SR Ca uptake in a activity-dependent fashion. Our results are also compatible with a background, activity-independent stimulation of SR Ca uptake by PKA in intact rat myocytes.

Role of Ca2+/calmodulin-dependent protein kinase II in the regulation of the cardiac L-type Ca2+ current during endothelin-1 stimulation

2010 ◽  
Vol 298 (6) ◽  
pp. H1902-H1907 ◽  
Author(s):  
Kimiaki Komukai ◽  
Jin O-Uchi ◽  
Satoshi Morimoto ◽  
Makoto Kawai ◽  
Kenichi Hongo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Patch Clamp ◽  
Receptor Antagonist ◽  
Ventricular Myocytes ◽  
Receptor Protein ◽  
Dependent Protein Kinase ◽  
Rat Ventricular Myocytes ◽  
Endothelin 1 ◽  
Protein Kinase Ii ◽  
Dependent Protein

Endothelin-1 (ET-1) shows a positive inotropic effect on cardiac muscle. Although the L-type Ca2+ current ( ICa) is one of the important determinants of cardiac excitation-contraction coupling, the effect of ET-1 on the ICa is not always clear. The controversial results appear to be due to different patch-clamp methods. The present study measured the effect of ET-1 on the ICa of rat ventricular myocytes using the perforated patch-clamp technique. The holding potential was set to −40 mV, and depolarization was applied every 10 s. ET-1 (10 nM) increased the ICa in a monophasic manner. The current reached a steady state 15 min after the application of ET-1, when the measurement was done. Endothelin receptor subtype expression was also investigated using Western immunoblotting. ETA-receptor protein was expressed, but ETB-receptor protein was not expressed, in the cell membranes of rat ventricular myocytes. The effect of ET-1 on the ICa was inhibited by a selective ETA-receptor antagonist, BQ-123, but not by a selective ETB-receptor antagonist, BQ-788. The effect was inhibited by protein kinase C (PKC) inhibitor chelerythrine and Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitor KN-93, but not by its inactive analog KN-92. The effect of ET-1 was also blocked by another CaMKII inhibitor, autocamtide-2-related inhibitory peptide. These results suggest that ET-1 increases the ICa via the ETA-receptor-PKC-CaMKII pathway.

Protein kinase inhibitors reduce SR Ca transport in permeabilized cardiac myocytes

1994 ◽  
Vol 267 (2) ◽  
pp. H812-H820 ◽  
Author(s):  
A. Mattiazzi ◽  
L. Hove-Madsen ◽  
D. M. Bers
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitors ◽  
Inhibitory Effect ◽  
Ruthenium Red ◽  
Protein Kinase Inhibitors ◽  
Inhibitory Peptide ◽  
Dependent Protein Kinase ◽  
Ca Transport ◽  
Ca Uptake ◽  
Dependent Protein

Phosphorylation of the sarcoplasmic reticulum (SR) protein phospholamban by adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA) and Ca-calmodulin-dependent protein kinase (CaM-KII) stimulates Ca-adenosinetriphosphatase (ATPase) activity and SR Ca transport, but the role of CaM-KII-dependent phosphorylation is not well defined. We studied the PKA- and CaM-KII-dependent regulation of SR Ca transport in digitonin-permeabilized rabbit ventricular myocytes. SR Ca uptake and free Ca concentration were measured on line with indo 1 and Ca electrodes in the presence of 20 microM ruthenium red and 10 mM oxalate. neither N5,2'-w-dibutyryl-cAMP (up to 500 microM) nor the nonhydrolyzable cAMP agonist adenosine 3'5'-cyclic monophosphorothioate sodium salt (Sp-cAMP[S]; up to 275 microM) affected the maximum uptake rate (Vmax) or the dissociation constant (Kd) for Ca uptake. However, the PKA inhibitor H-89 significantly increased Kd (e.g., from 307 +/- 67 to 826 +/- 62 nM Ca at 40-65 microM H-89) without significantly affecting Vmax. Both CaM-KII inhibitors, KN-62 (60 microM) and a CaM-KII inhibitory peptide (10 microM), significantly decreased Vmax from 11.95 +/- 0.5 to 9.48 +/- 0.6 nmol.mg-1.min-1 and from 10.95 +/- 1.72 to 7.37 +/- 0.94 nmol.mg-1.min-1, respectively, without consistently changing Kd. The effects of H-89 on Kd and of KN-62 on Vmax were prevented by a monoclonal antibody to phospholamban 2D12 (consistent with the antibody removing the inhibitory effect of phospholamban on the SR Ca-ATPase).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Chronic Elevation of Calmodulin in the Ventricles of Transgenic Mice Increases the Autonomous Activity of Calmodulin-Dependent Protein Kinase II, Which Regulates Atrial Natriuretic Factor Gene Expression

2000 ◽  
Vol 14 (8) ◽  
pp. 1125-1136 ◽  
Author(s):  
Josep M. Colomer ◽  
Anthony R. Means
Keyword(s):  
Gene Expression ◽  
Protein Kinase ◽  
Transgenic Mice ◽  
Atrial Natriuretic Factor ◽  
Ventricular Myocytes ◽  
Dependent Protein Kinase ◽  
Natriuretic Factor ◽  
Dependent Protein ◽  
Autonomous Activity

Abstract Although isoforms of Ca2+/calmodulin-dependent protein kinase II (CaMKII) have been implicated in the regulation of gene expression in cultured cells, this issue has yet to be addressed in vivo. We report that the overexpression of calmodulin in ventricular myocytes of transgenic mice results in an increase in the Ca2+/calmodulin-independent activity of endogenous CaMKII. The calmodulin transgene is regulated by a 500-bp fragment of the atrial natriuretic factor (ANF) gene promoter which, based on cell transfection studies, is itself known to be regulated by CaMKII. The increased autonomous activity of CaMKII maintains the activity of the transgene and establishes a positive feedforward loop, which also extends the temporal expression of the endogenous ANF promoter in ventricular myocytes. Both the increased activity of CaMKII and transcriptional activation of ANF are highly selective responses to the chronic overexpression of calmodulin. These results indicate that CaMKII can regulate gene expression in vivo and suggest that this enzyme may represent the Ca2+-dependent target responsible for reactivation of the ANF gene during ventricular hypertrophy.

Receptor-mediated endocytosis of urokinase-type plasminogen activator is regulated by cAMP-dependent protein kinase

1997 ◽  
Vol 110 (12) ◽  
pp. 1395-1402 ◽  
Author(s):  
L. Goretzki ◽  
B.M. Mueller
Keyword(s):  
Protein Kinase ◽  
Plasminogen Activator ◽  
Kinase Inhibitors ◽  
Melanoma Cells ◽  
Protein Kinase Inhibitors ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Dependent Protein

Internalization of the urokinase-type plasminogen activator (uPA) requires two receptors, the uPA receptor (uPAR) and the low density lipoprotein receptor-related protein (LRP)/alpha2-macroglobulin (alpha2M) receptor. Here, we address whether protein kinases are involved in the internalization of uPA by human melanoma cells. Initially, we found that the internalization of uPA was significantly inhibited by the serine/threonine protein kinase inhibitors staurosporine, K-252a and H-89, but not by the tyrosine kinase inhibitors, genistein and lavendustin A. Internalization of uPA was also inhibited by a pseudosubstrate peptide for cAMP-dependent protein kinase (PKA), but not by a pseudosubstrate peptide for protein kinase C. We confirmed a requirement for PKA-activity and implicated a specific isoform by using an antisense oligonucleotide against the regulatory subunit RI alpha of PKA which suppresses PKA-I activity. Exposure of cells to this oligonucleotide led to a specific, dose-dependent decrease in RI alpha protein and to a significant inhibition in the rate of uPA internalization. We further demonstrate that treatment of melanoma cells with either H-89 or PKA RI alpha antisense oligonucleotides also resulted in a decreased internalization of two other ligands of LRP, activated alpha2M and lactoferrin, indicating that PKA activity is associated with LRP. Finally, we demonstrate that PKA activity is also required for the internalization of transferrin, but not for the internalization of the epidermal growth factor or adenovirus 2, suggesting that in melanoma cells, PKA activity is not generally required for clathrin-mediated endocytosis, but is rather associated with specific internalization receptors.

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