[Molecular cloning and functional expression of a mouse adrenocorticotropin receptor gene]

Human genes for an adrenocorticotropin (ACTH) receptor and a melanocyte-stimulating hormone (MSH) receptor, and a mouse gene for a MSH receptor have been cloned recently. They constitute a family of receptors for peptides derived from proopiomelanocortin. The ACTH receptor mRNA and the MSH receptor mRNA were expressed only in the adrenal and melanocytes, respectively. Thereafter, three novel receptor genes for melanocortins were molecularly cloned and were expressed exclusively in the brain but not in the adrenal or melanocytes. It has remained unknown how these receptors are differentially expressed in specialized cell type. An adrenocortical cell line of mouse origin, Y-1, is to date the sole cell line which shows responsiveness to ACTH resulting in the induction of steroids. For analysis of the transcriptional regulation of ACTH receptor in Y-1 cells, I have isolated the mouse ACTH receptor gene. A 914 bp DNA fragment of the human ACTH receptor gene was amplified by polymerase chain reaction and used as a probe. Eight positive clones were obtained by screening 10(6) phage clones of a mouse genomic library under the condition of low stringency. One phage clone, lambda mCTR8 which gave the most intense hybridization signal was analyzed. It contained an approximately 12 kb insert. By comparing it with the previously reported human ACTH receptor gene and bovine ACTH receptor cDNA, the mouse homologue is intron-less in its coding region, and has a potential to encode for a 296-amino-acid polypeptide which possesses 88.9% and 78.7% identities to the human and bovine ACTH receptors, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)