Naturally occurring genetic mutations in the 5'-upstream regulatory region of bovine FSHB generate a novel cis-regulatory element that affects its expression.

We previously reported that numerous naturally occurring genetic mutations in the 5'-upstream regulatory region (5'-URR) of the bovine follicle-stimulating hormone beta-subunit gene (FSHB) were associated with reduced serum follicle-stimulating hormone (FSH) levels, poor-quality semen and low fertility in bulls. In addition, two different FSHB mRNA transcripts resulting from the linked mutations of genomic DNA were discovered in mutation-bearing bull pituitaries. Here, using electrophoretic mobility shift assay, we identified c.-1539_-1538delGGinsTTAACT mutations in the 5'-URR that generated a novel cis-regulatory element in bovine FSHB. Moreover, this novel element seemed to play a role in repressing FSHB transcription based on a promoter activity analysis in LβT2 gonadotrope cells. Quantitative assays of FSHB mRNA in the bovine pituitaries suggested that the levels of FSHB wild-type transcripts in the mutation-bearing bulls were significantly lower (P < 0.05) than in those of bulls without FSHB genetic mutations and that the levels of FSHB-mutated transcripts were significantly lower (P < 0.05) than that of wild-type transcripts in the mutation-bearing bulls. Altogether, our results suggest that decreased serum FSH levels and male fertility in bulls with the c.-1539_-1538delGGinsTTAACT mutation likely result from the alteration of cis-regulatory elements and induction of FSHB transcription.