Cloning, expression, and tissue distribution of the rat homolog of the bovine α1C-adrenergic receptor provide evidence for its classification as the α1A subtype

Dianne M. Perez, Michael T. Piascik, Niveen Malik, Robert Gaivin, Robert M. Graham

Research output: Contribution to journalArticlepeer-review

120 Scopus citations

Abstract

Three α1-adrenergic receptors (ARs) have been cloned, i.e., the α1B-, α1C-, and α1D-ARs. Compared with the α1B subtype, the α1A subtype in tissue is described as being insensitive to chloroethylclonidine and sensitive to SZL-49 and having a 10-100-fold higher affinity for a number of agonists and antagonists. The α1A subtype is also expressed in a variety of rat tissues (as assessed by pharmacology), with greatest abundance in the cerebral cortex, hippocampus, vas deferens, and submaxillary gland. The cloned bovine α1C-AR, though having an α1A-AR pharmacology, was first reported as not being expressed in any rat tissue (as determined by Northern analysis) and was therefore designated as a new subtype. We report the cloning, expression, and characterization of the rat homolog of the bovine α1C-AR. Using a human α1C-AR probe obtained by polymerase chain reaction screening of a neuroblastoma cell line (SK-N-MC), both exon 1 and exon 2 of the rat α1C-AR gene were cloned from a rat genomic library. These two exons were spliced together and cloned into the expression vector pMT2′. Transfection into COS-1 cells and analysis of the ligand-binding profile of the expressed protein receptor using 125I-HEAT revealed a 10-100-fold higher affinity for the α1-AR antagonists 5-methylurapidil, (+)-niguldipine, WB-4101, and phentolamine and the agonists oxymetazoline and methoxamine, compared with the α1B-AR. This ligand-binding profile is similar to that for endogenously expressed tissue α1A-ARs. In addition, the rat α1C-AR was the least sensitive of the three cloned subtypes to the alkylating effects of chloroethylclonidine but was the most sensitive to the alkylating prazosin analog SZL-49, properties also observed for the tissue α1A subtype. Furthermore, by three different techniques, i.e., RNase protection assays, reverse transcription-polymerase chain reaction Northern blotting, and in situ hybridization histochemistry, the rat α1C-AR mRNA was localized to α1A-AR-rich tissues, such as rat vas deferens, hippocampus, aorta, and submaxillary gland. Taken together, these data suggest that this receptor may actually represent the α1A subtype.

Original languageEnglish
Pages (from-to)823-831
Number of pages9
JournalMolecular Pharmacology
Volume46
Issue number5
StatePublished - Nov 1994

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

Fingerprint

Dive into the research topics of 'Cloning, expression, and tissue distribution of the rat homolog of the bovine α1C-adrenergic receptor provide evidence for its classification as the α1A subtype'. Together they form a unique fingerprint.

Cite this