beta-Adrenergic receptor stimulated Ncx1 upregulation is mediated via a CaMKII/AP-1 signaling pathway in adult cardiomyocytes.
The Na(+)-Ca(2+) exchanger gene (Ncx1) is upregulated in hypertrophy and is often found elevated in end-stage heart failure. Studies have shown that the change in its expression contributes to contractile dysfunction. beta-Adrenergic receptor (beta-AR) signaling plays an important role in the regulation of calcium homeostasis in the cardiomyocyte, but chronic activation in periods of cardiac stress contributes to heart failure by mechanisms which include Ncx1 upregulation. Here, using a Ca(2+)/calmodulin-dependent protein kinase II (CaMKIIdelta(c)) null mouse, we demonstrate that beta-AR-stimulated Ncx1 upregulation is dependent on CaMKII. beta-AR-stimulated Ncx1 expression is mediated by activator protein 1 (AP-1) factors and is independent of cAMP-response element-binding protein (CREB) activation. The MAP kinases (ERK1/2, JNK and p38) are not required for AP-1 factor activation. Chromatin immunoprecipitation demonstrates that beta-AR stimulation activates the ordered recruitment of JunB homodimers, which then are replaced by c-Jun homodimers binding to the proximal AP-1 elements of the endogenous Ncx1 promoter. In conclusion, this work has provided insight into the intracellular signaling pathways and transcription factors regulating Ncx1 gene expression in a chronically beta-AR-stimulated heart.
Mani
Santhosh K
SK
Division of Cardiology, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, 114 Doughty Street, Box 250773, Charleston, SC 29425, USA.
Egan
Erin A
EA
Addy
Benjamin K
BK
Grimm
Michael
M
Kasiganesan
Harinath
H
Thiyagarajan
Thirumagal
T
Renaud
Ludivine
L
Brown
Joan Heller
JH
Kern
Christine B
CB
Menick
Donald R
DR
D000375:Aging / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002415:Cats; D000242:Cyclic AMP / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D017353:Gene Deletion; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D019831:Sodium-Calcium Exchanger / Q000235:genetics* / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics*
D017362:Cyclic AMP Response Element-Binding Protein; D047428:Protein Kinase Inhibitors; D016755:Proto-Oncogene Proteins c-jun; D011943:Receptors, Adrenergic, beta; D019831:Sodium-Calcium Exchanger; D018808:Transcription Factor AP-1; C110374:sodium-calcium exchanger 1; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D020928:Mitogen-Activated Protein Kinases