Cloning and characterization of the mouse alpha1C/A-adrenergic receptor gene and analysis of an alpha1C promoter in cardiac myocytes: role of an MCAT element that binds transcriptional enhancer factor-1 (TEF-1).
alpha1-Adrenergic receptor (AR) subtypes in the heart are expressed by myocytes but not by fibroblasts, a feature that distinguishes alpha1-ARs from beta-ARs. Here we studied myocyte-specific expression of alpha1-ARs, focusing on the subtype alpha1C (also called alpha1A), a subtype implicated in cardiac hypertrophic signaling in rat models. We first cloned the mouse alpha1C-AR gene, which consisted of two exons with an 18 kb intron, similar to the alpha1B-AR gene. The receptor coding sequence was >90% homologous to that of rat and human. alpha1C-AR transcription in mouse heart was initiated from a single Inr consensus sequence at -588 from the ATG; this and a putative polyadenylation sequence 8.5 kb 3' could account for the predominant 11 kb alpha1C mRNA in mouse heart. A 5'-nontranscribed fragment of 4.4 kb was active as a promoter in cardiac myocytes but not in fibroblasts. Promoter activity in myocytes required a single muscle CAT (MCAT) element, and this MCAT bound in vitro to recombinant and endogenous transcriptional enhancer factor-1. Thus, alpha1C-AR transcription in cardiac myocytes shares MCAT dependence with other cardiac-specific genes, including the alpha- and beta-myosin heavy chains, skeletal alpha-actin, and brain natriuretic peptide. However, the mouse alpha1C gene was not transcribed in the neonatal heart and was not activated by alpha1-AR and other hypertrophic agonists in rat myocytes, and thus differed from other MCAT-dependent genes and the rat alpha1C gene.
O'Connell
T D
TD
Cardiology Division and Research Service, Veterans Affairs Medical Center, San Francisco, California, USA.
Rokosh
D G
DG
Simpson
P C
PC
D000595:Amino Acid Sequence; D000818:Animals; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006321:Heart / Q000254:growth & development / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics* / Q000378:metabolism; D020218:Response Elements / Q000187:drug effects / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D000091262:TEA Domain Transcription Factors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D018340:Receptors, Adrenergic, alpha-1; D000091262:TEA Domain Transcription Factors; C083215:Tead1 protein, mouse; D014157:Transcription Factors; D015500:Chloramphenicol O-Acetyltransferase; D009638:Norepinephrine