Renal tubular Sirt1 attenuates diabetic albuminuria by epigenetically suppressing Claudin-1 overexpression in podocytes
Author(s)
Hasegawa, Kazuhiro; Wakino, Shu; Simic, Petra; Sakamaki, Yusuke; Minakuchi, Hitoshi; Fujimura, Keiko; Hosoya, Kozi; Komatsu, Motoaki; Kaneko, Yuka; Kanda, Takeshi; Kubota, Eiji; Tokuyama, Hirobumi; Itoh, Hiroshi; Guarente, Leonard Pershing; Hayashi, Koichi, 1967-; ... Show more Show less
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Sirtuin 1 (Sirt1), a NAD[superscript +]-regulated deacetylase with numerous known positive effects on cellular and whole-body metabolism, is expressed in the renal cortex and medulla. It is known to have protective effects against age-related disease, including diabetes. Here we investigated the protective role of Sirt1 in diabetic renal damage. We found that Sirt1 in proximal tubules (PTs) was downregulated before albuminuria occurred in streptozotocin-induced or obese (db/db) diabetic mice. PT-specific SIRT1 transgenic and Sirt1 knockout mice showed prevention and aggravation of the glomerular changes that occur in diabetes, respectively, and nondiabetic knockout mice exhibited albuminuria, suggesting that Sirt1 in PTs affects glomerular function. Downregulation of Sirt1 and upregulation of the tight junction protein Claudin-1 by SIRT1-mediated epigenetic regulation in podocytes contributed to albuminuria. We did not observe these phenomena in 5/6 nephrectomized mice. We also demonstrated retrograde interplay from PTs to glomeruli using nicotinamide mononucleotide (NMN) from conditioned medium, measurement of the autofluorescence of photoactivatable NMN and injection of fluorescence-labeled NMN. In human subjects with diabetes, the levels of SIRT1 and Claudin-1 were correlated with proteinuria levels. These results suggest that Sirt1 in PTs protects against albuminuria in diabetes by maintaining NMN concentrations around glomeruli, thus influencing podocyte function.
Date issued
2013-10Department
Massachusetts Institute of Technology. Department of BiologyJournal
Nature Medicine
Publisher
Nature Publishing Group
Citation
Hasegawa, Kazuhiro, Shu Wakino, Petra Simic, Yusuke Sakamaki, Hitoshi Minakuchi, Keiko Fujimura, Kozi Hosoya, et al. “Renal Tubular Sirt1 Attenuates Diabetic Albuminuria by Epigenetically Suppressing Claudin-1 Overexpression in Podocytes.” Nature Medicine 19, no. 11 (October 20, 2013): 1496–1504.
Version: Author's final manuscript
ISSN
1078-8956
1546-170X