HIV viral protein R induces loss of DCT1-type renal tubules

Abstract

HIV viral protein R (Vpr) contributes to HIV-associated nephropathy, induces cell cycle arrest, and alters expression of mineralocorticoid-responsive genes. To investigate Vpr modulation of aldosterone-mediated regulation of the expression of Na-Cl cotransporter Slc12a3 and sodium reabsorption in distal nephron segments, we performed single-nucleus RNA sequencing of kidney cortices of wild-type (WT) and Vpr transgenic (Vpr Tg) mice on low sodium diet and a WT mouse on regular chow. In Vpr Tg mouse, Slc12a3 expression was downregulated in connecting tubules (CNT) and late distal convoluted tubules (DCT2) but not in early DCT (DCT1). Mineralocorticoid receptor (Nr3c2) expression was higher in CNT and DCT2 than in DCT1. DCT1 cell percentage in salt-depleted Vpr Tg was lower (1.8%) compared with salt-depleted or salt-replete WT (3.7% and 3.6%, respectively). Sub-clustering confirmed that Pvalb+ DCT1 subcluster had fewer cells in Vpr Tg (0.95%) compared with salt-depleted or salt-replete WT (2.9% and 3.1%, respectively). Autophagy and protein ubiquitination genes were upregulated in DCT1 subcluster of Vpr Tg mice. In situ hybridization and immunohistochemistry demonstrated fewer Slc12a3+ Pvalb+ DCT1 segments in Vpr Tg mice. Downregulation of Slc12a3 and higher levels of Nr3c2 in the CNT/DCT2 suggested that the aldosterone-mediated upregulation of Slc12a3 with salt depletion was most prominently inhibited by Vpr in the CNT/DCT2. These observations demonstrate that the salt-wasting effect of Vpr in Vpr Tg mice is mediated by loss of Slc12a3+ Pvalb+ DCT1 segments. The downregulation of Slc12a3 occurred in more distal segments rather than in DCT1.