Cytochrome P450 Transcriptional Regulation by Testis-Specific Y-Encoded-Like Protein: Identification of Novel Upstream Transcription Factors.

Cytochrome P450s () display significant inter-individual variation in expression, much of which remains unexplained by known single-nucleotide polymorphisms (SNPs). Testis-specific Y-encoded-like proteins (s) are transcriptional regulators for several drug-metabolizing including However, transcription factors (TFs) that might influence expression through an effect on expression are unknown. Therefore, we studied regulators of expression in hepatic cell lines and their possible SNP-dependent variation. Specifically, we identified candidate TFs that might influence expression using the ENCODE ChIPseq database. Subsequently, the expression of as well as that of selected CYP targets for regulation were assayed in hepatic cell lines before and after knockdown of TFs that might influence expression through TSPYL-dependent mechanisms. Those results were confirmed by studies of TF binding to gene promoter regions. In hepatic cell lines, knockdown of the REST and ZBTB7A TFs resulted in decreased and expression and increased expression, changes reversed by overexpression. Potential binding sites for and on the promoters of and were confirmed by chromatin immunoprecipitation. Finally, common SNP variants in upstream binding sites on the promoters were identified and luciferase reporter constructs confirmed SNP-dependent modulation of gene transcription. In summary, we identified REST and ZBTB7A as regulators of the expression of TSPYL genes which themselves can contribute to regulation of expression and-potentially-of drug metabolism. SNP-dependent modulation of TSPYL transcription may contribute to individual variation in both expression and-downstream-drug response phenotypes. SIGNIFICANCE STATEMENT: Testis-specific Y-encoded-like proteins (s) are transcriptional regulators of cytochrome P450 () gene expression. Here, we report that variation in expression as a result of the effects of genetically regulated TSPYL transcription factors is an additional factor that could result in downstream variation in expression and potentially, as a result, variation in drug biotransformation.