Regulation of NCC and the WNK cascade by the circadian clock protein Per1 in murine distal convoluted tubule cells (1109.5)

Abstract

Blood pressure and renal function undergo circadian fluctuations. We have shown that the circadian protein Per1 regulates genes involved in sodium (Na) transport in the kidney collecting duct, but has not been investigated in other parts of the nephron. The distal convoluted tubule (DCT) plays a critical role in Na reabsorption in the nephron through the actions of the Na‐Cl co‐transporter (NCC), which is regulated by the with‐no‐lysine kinases (WNKs). Therefore, we wanted to test the hypothesis that Per1 regulates Na transport in the DCT through modulation of NCC, WNK1 and WNK4.Pharmacological blockade of nuclear Per1 entry resulted in decreased mRNA expression of NCC and WNK1, but increased expression of WNK4 in mouse renal cortex. These findings were confirmed by Per1 siRNA and pharmacological blockade of Per1 nuclear entry in mDCT15 cells, a model of the mouse distal convoluted tubule. Measurement of short‐lived hnRNA demonstrated that the effect of Per1 was transcriptional. Chromatin immunoprecipitation experiments demonstrated interaction of Per1 and CLOCK with the promoters of NCC, WNK1, and WNK4; blockade of Per1 nuclear entry abolished these effects. Importantly, NCC activity, as measured by thiazide‐sensitive, Cl‐dependent 22Na uptake, was decreased upon pharmacological inhibition of Per1 nuclear entry. These data demonstrate a role for Per1 in the transcriptional regulation of NCC, WNK1, and WNK4.Grant Funding Source: Supported by NIH, ASN and AHA