The Catsper3 promoter activity is regulated by the cAMP-Response Element Modulator tau (CREMτ) and the cAMP-Response Element Binding protein 1A (CREBA) transcription factors

Catsper3 has been shown to be essential for the proper functioning of CatSper calcium channel, sperm hyperactivation and egg fertilization. Although its function and physiological relevance to male fertility have been characterized, nothing is known about its regulation at the transcriptional level. Here, we identified the murine Catsper3 promoter and evaluated the role of CREBA and CREMτ transcription factors (TF) on its regulation. Cloning of a predicted Catsper3 promoter region and further deletion analysis indicates that Catsper3 core promoter is located at -157 to +152 relative to the transcription start site (TSS). Mutation of a TATA box and a Downstream Promoter Element (DPE) did not alter the promoter activity, indicating that this promoter is TATA and DPE independent. Exogenous expression of CREBA and CREMτ increase the Catsper3 promoter activity in the presence of the +268 to +439 region, where two CRE sites were predicted, and mutation of both CRE sites prevents the transactivation by both TFs, suggesting that CREMτ and CREBA may use these sites to promote Catsper3 transcription. Finally, binding of CREBA and CREMτ to both CRE sites was confirmed in vitro by EMSA and ChIP-qPCR assays demonstrated an enrichment of CREBA and CREMτ at the Catsper3 promoter in vivo in the testis but not in liver, indicating its tissue-specific binding. Altogether, these results strongly suggest that Catsper3 gene has a TATA-less, DPE independent promoter encompassed by -157 to +152 region around TSS and that Catsper3 gene expression is directly regulated through two CRE sites by CREBA and CREMτ.