Effects of HTR1B 3' region polymorphisms and functional regions on gene expression regulation

Abstract

Background The HTR1B gene encodes the 5-hydroxytryptamine (5-HT1B) receptor, which is involved in a variety of brain activities and mental disorders. The regulatory effects of non-coding regions on genomic DNA are one of many reasons for the cause of genetic-related diseases. Post-transcriptional regulation that depends on the function of 3' regulatory regions plays a particularly important role. This study investigated the effects, on reporter gene expression, of several haplotypes of the HTR1B gene (rs6297, rs3827804, rs140792648, rs9361234, rs76194807, rs58138557, and rs13212041) and truncated fragments in order to analyze the function of the 3' region of HTR1B. Methods Seven haplotypes, consisting of rs6297, rs3827804, rs140792648, rs9361234, rs76194807, rs58138557, and rs13212041, and truncated fragments of the HTR1B gene 3' region were transfected into SK-N-SH, HEK-293, and U87 cell lines. The relative fluorescence intensities were detected by a dual luciferase reporter assay system.Results We found that the haplotype, AG_CT_A, enhanced the expression level compared to the main haplotype; AG_CG_A; GG_CG_G decreased the expression level. Two alleles, rs76194807T and rs6297G, exhibited different relative luciferase intensities compared to their counterparts at each locus. We also found that +2440 ~ +2769 bp and +1953 ~ +2311 bp regions both had negative effects on gene expression.ConclusionsThe 3' region of HTR1B has a regulatory effect on gene expression, which is likely closely associated with the interpretation of HTR1B-related disorders. In addition, the HTR1B 3' region includes several effector binding sites that induce an inhibitory effect on gene expression.