Transcriptional regulation of olfactory receptor OR51B5 by the TBX6.

Olfactory receptors (ORs) are G protein-coupled receptors primarily expressed in olfactory tissue, facilitating the perception of odors. Interestingly, they have also been detected in non-olfactory tissues such as the skin, where they regulate processes like collagen synthesis. This study aimed to analyze the promoter of the OR family 51 subfamily B member 5 (OR51B5) and identify the transcription factors that bind to it to understand the potential regulatory mechanisms for OR51B5 expression. We examined the promoter region spanning 2,000 base pairs upstream of the transcription start site and conducted a deletion analysis, revealing that the core promoter encompasses the region from -153 to -111 base pairs. A luciferase assay using various candidate transcription factors showed that the overexpression or knockdown of T-Box Transcription Factor 6 (TBX6) significantly regulated OR51B5 promoter activity, while other candidate transcription factors had no significant effect. Additionally, we validated TBX6 binding to the OR51B5 promoter using site-directed mutation and electrophoretic mobility shift assays. This study is the first to uncover the role of TBX transcription factors in regulating OR gene expression in mammals, which may have implications for treating related disorders.