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).