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

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.

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.

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.

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.