Identification of Genetic Variation in the Human Hormone-Sensitive Lipase Gene and 5′ Sequences: Homology of 5′ Sequences with Mouse Promoter and Identification of Potential Regulatory Elements

Abstract

Hormone-sensitive lipase (HSL) plays a crucial role in triglyceride hydrolysis in adipose tissue and exhibits cholesterol hydrolase activity in steroidogenic tissue and macrophages. Thus, common genetic variation in the HSL gene could affect both energy metabolism and atherogenesis. Using overlapping single-strand conformational polymorphism analysis (SSCP), a common single base change (T/C) in intron 4 [allele frequency 0.012 (95% CI 0.007–0.018)] and a variable CA repeat in intron 6 with 9 alleles (heterozygosity index = 0.66) were identified. Sequence of 1.123 kb upstream from the reported 5′UTR (1) which includes intron B, exon B, and 159 bp of the promoter (2) was obtained and a single common nucleotide change, −60C/G [allele frequency 0.052 (95% CI 0.039–0.064)], identified. Preliminaryin vitrostudies show that the −60G construct has 38.5% lower luciferase activity compared to the −60C construct (P= 0.035), suggesting a functional change affecting HSL gene expression. The 5′ sequence shows 57–59% homology with the mouse promoter with higher homology at potential regulatory motifs. Thus, the 1.7 kb of 5′ sequences is well conserved and may play a part in the regulation of HSL gene expression.