Neural Upregulation of SGLT2-MAP17-PDZK1 Complex in Kidneys of Rats With Heart Failure.

Abstract

BACKGROUND: Congestive heart failure (CHF) is characterized by the activation of neurohumoral drive concomitant with avid fluid retention. Renal denervation alleviates this fluid retention. SGLT2 (sodium-glucose cotransporter 2) inhibitors have shown remarkable improvement in patients with cardiovascular diseases. We have recently demonstrated a relationship between enhanced renal sympathetic nerve activity and SGLT2 expression as well as function during CHF; however, the precise molecular mechanisms involved in the expression and translocation of SGLT2 and associated scaffolding proteins to the luminal membrane remain to be examined. METHODS: CHF was induced by coronary artery ligation followed by bilateral renal denervation 4 weeks later, in rats. Western blot analysis and immunohistochemistry were performed to evaluate changes in the expression of SGLT2, MAP17 (membrane-associated protein 17), PDZK1 (PDZ domain containing 1), and activation of ERK (extracellular signal-regulated kinase)/NF-KB (nuclear factor κB) in renal cortex. Human adult proximal tubular cells were used to determine the direct effect of norepinephrine on the expression of SGLT2-MAP17-PDZK1 and activation of the ERK/NF-KB pathway. RESULTS: Rats with CHF exhibited significantly enhanced expression of SGLT2, MAP17, and PDZK1 with a concomitant significant activation of ERK and NF-KB in the renal cortex. In rats with CHF, renal denervation mitigated enhanced expression of SGLT2-MAP17-PDZK1 as well as activation of ERK and NF-KB. Direct action of norepinephrine on human adult proximal tubular cells triggered enhanced expression of SGLT2-MAP17-PDZK1 by the activation of the ERK/NF-KB pathway. CONCLUSIONS: Enhanced basal renal sympathetic nerve activity in CHF activates the ERK/NF-KB pathway, which in turn facilitates the enhanced expression and translocation of the SGLT2-MAP17-PDZK1 scaffolding protein complex to the luminal membrane, augmenting sodium reabsorption in CHF.