Angiotensin II (Ang II) type-2 receptors (ATR) are expressed in the adult kidney, prominently in renal proximal tubule cells (RPTCs), and play an important role in opposing renal sodium (Na) retention induced by Ang II stimulation of Ang II type-1 receptor (ATR). Natriuresis induced by ATR blockade is due at least in part to ATR activation and whole body deletion of ATRs reduces the natriuretic response to increased blood pressure (BP). The major endogenous ATR agonist mediating the natriuretic response is Ang III, the Ang II heptapeptide metabolite generated by aminopeptidase A, and the principal nephron site mediating inhibition of Na reabsorption by the ATR is the renal proximal tubule (RPT). ATRs induce natriuresis via a bradykinin, nitric oxide and cyclic GMP (cGMP) signaling cascade. Recent studies demonstrated a key role for protein phosphatase 2A (PP2A) in the ATR-mediated natriuretic response upstream of cGMP. By inducing natriuresis, ATRs lower BP in the Ang II-infusion model of hypertension. PP2A activation and the natriuretic response to ATR stimulation are defective in spontaneously hypertensive rats, a model of primary hypertension in humans. ATR agonists are candidates for proximal tubule natriuretic agents in Na and fluid retention disorders.
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http://dx.doi.org/10.3390/ijms23042317 | DOI Listing |
Calcineurin inhibitors (CNIs) are indispensable immunosuppressants for transplant recipients and patients with autoimmune diseases, but chronic use causes nephrotoxicity, including kidney fibrosis. Why inhibiting calcineurin, a serine/threonine phosphatase, causes kidney fibrosis remains unknown. We performed single-nucleus RNA sequencing of the kidney from a chronic CNI nephrotoxicity mouse model and found an increased proportion of injured proximal tubule cells, which exhibited altered expression of genes associated with oxidative phosphorylation, cellular senescence and fibrosis.
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Department of Medicine, Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
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Laboratory of Structural Biology, Departament of Biology, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil; Department of Veterinary, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil. Electronic address:
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Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA.
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