Nucleotide polymorphisms and the 5'-UTR transcriptional analysis of the bovine growth hormone secretagogue receptor 1a (GHSR1a) gene.

ABSTRACT

Growth hormone secretagogue receptor 1a (GHSR1a) mediates the different actions of its endogenous ligand, ghrelin. Ghrelin-GHSR is involved in many important functions that include growth hormone secretion and food intake. We evaluated the haplotype variety and characterized the microsatellite ((TG)(n) , 5'-UTR) and nucleotide polymorphisms of the bovine GHSR1a gene. The nucleotide sequencing of this gene (∼6 kb) revealed 47 single nucleotide polymorphisms (SNPs), four indels and the microsatellite ((GTTT)(n) , Intron 1). The 19 haplotypes were constructed from all nucleotide viability patterns and were divided into three major groups. Four SNPs (L24V, nt456(G>A), D191N and nt667(C>T)) and DelR242 in Exon 1 and a haplotype block of approximately 2.2 kb (nt667(C>T) ∼ nt2884 (A>G)) were found in Bos taurus breeds. Breed differences in allele frequencies of the two microsatellites, nt-7(C>A), L24V, and DelR242 loci were found (P < 0.005). A DelR242 was found in the Japanese Shorthorn (frequency ∼ 0.44), Japanese Brown, five European cattle breeds, the Philippine native cattle, but none detected in the Japanese Black or the Mishima island cattle. Additionally, 5'-rapid amplification of cDNA ends and RT-PCR analyses revealed that there were two different kinds of transcripts spliced, without a microsatellite within 5'-UTR (GHSR1a); and non-spliced, with the microsatellite (GHSR1b).