CREB-family transcription factors and vasopressin-mediated regulation of Aqp2 gene transcription

Water homeostasis is regulated by the peptide hormone arginine vasopressin (AVP), which promotes water reabsorption in the renal collecting duct. The regulation of Aqp2 gene transcription is a key mechanism through which AVP modulates water transport as disruption of this mechanism leads to water balance disorders. Therefore, an important goal is to understand the regulatory processes that control Aqp2 gene transcription. While CREB (CREB1) has been proposed as the primary transcription factor responsible for Aqp2 transcription, recent evidence challenges this view, suggesting that other CREB-like transcription factors, including ATF1 and CREM, may play a role. We employed the CRISPR/Cas9 gene-editing system to delete Atf1, Creb1, and Crem in mpkCCD cells, an immortalized collecting duct cell line. These cell lines were then exposed to the vasopressin analog dDAVP to assess the role of these transcription factors in regulating Aqp2 expression. Deletion of all three transcription factors (ATF1, CREB1, and CREM) led to a significant reduction in the vasopressin-induced upregulation of AQP2 protein, confirming their role in regulating Aqp2 expression. Rescue experiments in triple knockout cells showed that expressing any of the three transcription factors restored the response to vasopressin. RNA-seq data showed that Aqp2 mRNA levels mirrored changes in protein abundance, supporting the idea that these transcription factors affect Aqp2 transcription. Our findings demonstrate that ATF1, CREB1, and CREM have redundant roles in regulating Aqp2 transcription. Our results suggest that these transcription factors might regulate the expression of other unidentified transcription factors involved in Aqp2 regulation.