Regulation of DHP receptor expression by elements in the 5′-flanking sequence

Abstract

The alpha(1)-subunit of the cardiac/vascular Ca(2+) channel, which is the dihydropyridine (DHP)-binding site (the DHP receptor), provides the pore structure for Ca(2+) entry. It contains the binding sites for multiple classes of drugs collectively known as Ca(2+) antagonists. As an initial step toward understanding the mechanisms controlling transcription of the rat cardiac alpha(1C)-subunit gene, we have cloned a 2.3-kb fragment containing the 5'-flanking sequences and identified the alpha(1C)-subunit gene transcription start site. The rat alpha(1C)-subunit gene promoter belongs to the TATA-less class of such basal elements. Using deletion analysis of alpha(1C)-subunit promoter-luciferase reporter gene constructs, we have characterized the transcriptional modulating activity of the 5'-flanking region and conducted transient transfections in cultured neonatal rat cardiac ventricular myocytes and vascular smooth muscle cells. Sequence scanning identified several potential regulatory elements, including five consensus sequences for the cardiac-specific transcription factor Nkx2.5, an AP-1 site, a cAMP response element, and a hormone response element. Transient transfection experiments with the promoter-luciferase reporter fusion gene demonstrate that the 2-kb 5'-flanking region confers tissue specificity and hormone responsiveness to expression of the Ca(2+) channel alpha(1C)-subunit gene. Electrophoretic mobility shift assays identified a region of the alpha(1C)-subunit gene promoter that can bind transcription factors and appears to be important for gene expression.

JAK2/STAT3 Directs Cardiomyogenesis Within Murine Embryonic Stem Cells In Vitro

“…One possibility is that STAT3 binds the 5' untranslated region of the cardiac actin gene directly via its STAT binding element [44]. We were not able to find evidence supporting a direct interaction between STAT3 and the α1 subunit of the DHP receptor, but upon closer inspection of the promoter studies by Liu et al [41], we noticed a C/EBPβ binding site in the area critical for gene expression. C/EBPs have been shown to be reliant on STAT3 for expression [34,35].…”

Regulation of CREB signaling through L-type Ca2+channels by Nipsnap-2

“…31 Since our depolarization stimulus was 75 mM KCl, presumably an increase in Ca 2+ influx via Ca V 1.2 channels accounts for Nipsnap2-mediated increase in CREB activation. Interestingly, the 5' region of the gene encoding Ca V 1.2 contains a CRE-sequence, 32 and increased CREB signaling can lead to upregulation of Ca V 1.2. 33 As we observed an increase in CREB expression this may explain the increase in Ca V 1.2 mRNA expression, although it is currently unclear why protein levels were unaffected.…”

L-Type Ca2+Channels Mediate Adaptation of Extracellular Signal-Regulated Kinase 1/2 Phosphorylation in the Ventral Tegmental Area after Chronic Amphetamine Treatment

“…The Ca v 1.2 gene contains the upstream regulatory sites CRE and AP1, which bind CREB and the Fos family of proteins, respectively (Liu et al, 2000). These regulatory sites and their transcription factors are activated by psychostimulants and are involved in psychostimulant-induced changes (Berke and Hyman, 2000;Nestler, 2001a).…”