Regulation of Ncx1 gene expression in the normal and hypertrophic heart.
The Na+/Ca2+ exchanger (NCX1) is crucial in the regulation of [Ca2+]i in the cardiac myocyte. The exchanger is upregulated in cardiac hypertrophy, ischemia, and failure. This upregulation can have an effect on Ca2+ transients and possibly contribute to diastolic dysfunction and an increased risk of arrhythmias. Studies from both in vivo and in vitro model systems have provided an initial skeleton of the potential signaling pathways that regulate the exchanger during development, growth, and hypertrophy. The Ncx1 gene is upregulated in response to alpha-adrenergic stimulation. We have shown that this is via p38alpha activation of transcription factors binding to the Ncx1 promotor at the -80 CArG element. Interestingly, most of the elements, including the CArG element, which we have demonstrated to be important for regulation of Ncx1 expression are in the proximal 184 bp of the promotor. Using a transgenic mouse, we have shown that the proximal 184 bp is sufficient for expression of reporter genes in adult cardiomyocytes and for the correct spatiotemporal pattern of Ncx1 expression in development but not for upregulation in response to pressure overload.
Menick
Donald R
DR
Division of Cardiology, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, 114 Doughty St., Charleston, SC 29425, USA. menickd@musc.edu
Renaud
Ludivine
L
Buchholz
Avery
A
Müller
Joachim G
JG
Zhou
Hongming
H
Kappler
Christiana S
CS
Kubalak
Steven W
SW
Conway
Simon J
SJ
Xu
Lin
L
D000818:Animals; D006332:Cardiomegaly / Q000235:genetics*; D005786:Gene Expression Regulation; D009206:Myocardium / Q000378:metabolism; D011401:Promoter Regions, Genetic; D019831:Sodium-Calcium Exchanger / Q000235:genetics*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D019831:Sodium-Calcium Exchanger; C110374:sodium-calcium exchanger 1; D048051:p38 Mitogen-Activated Protein Kinases