The effect of a mutation in the 3-UTR region of the HMGCR gene on cholesterol in Beijing-you chickens.

The 3-hydroxyl-3-methylglutaryl Coenzyme A reductase (HMGCR) gene was examined for polymorphisms in Beijing-you chickens. A "T" base insert was detected at nucleotide 2749 of the 3-UTR region of the HMGCR gene and was used as the basis for distinguishing a B allele, distinct from the A. Serum and muscle contents of total cholesterol. LDL-cholesterol in serum was significantly lower in AB birds and lowest in BB birds. Real-time PCR showed that the same trends across genotypes occurred in an abundance of HMGCR transcripts in liver, but there was no difference in contents of HMGCR mRNA in breast or thigh muscles. Hepatic expression and serum LDL-cholesterol were meaningfully correlated (partial, with total serum cholesterol held constant, r = 0.923). In muscle, similar genotypic differences were found for the abundance of the LDL receptor (LDLR) transcript. Cholesterol content in breast muscle related to LDLR expression (partial correlation with serum LDL-cholesterol held constant, r = 0.719); the equivalent partial correlation in thigh muscle was not significant. The results indicated that the B allele significantly reduces hepatic abundance of HMGCR transcripts, probably accounting for genotypic differences in serum cholesterol. In muscle, the cholesterol content appeared to reflect differences in LDLR expression with apparent mechanistic differences between breast and thigh.