PRDM16 acts as a therapeutic downstream target of TGF-β signaling in chronic kidney disease
Qian Yuan, Ben Tang, Yuting Zhu, Chao Wan, Yaru Xie, Yajuan Xie, Cheng Wan, Hua Su, Youhua Liu, Chun Zhang
Qian Yuan, Ben Tang, Yuting Zhu, Chao Wan, Yaru Xie, Yajuan Xie, Cheng Wan, Hua Su, Youhua Liu, Chun Zhang
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Research Article Metabolism Nephrology

PRDM16 acts as a therapeutic downstream target of TGF-β signaling in chronic kidney disease

Abstract

Transforming growth factor β (TGF-β) signaling is the master modulator of renal fibrosis. However, targeting drugs have failed to prevent the progression of chronic kidney disease (CKD) in clinical trials due to the extensive biological regulation of TGF-β signaling. It is necessary to investigate the precise downstream mechanisms of TGF-β signaling that regulate renal fibrosis. In this study, we found that PR-domain containing 16 (PRDM16) expression in human renal tubular epithelial cells was markedly reduced by TGF-β. Mechanistically, activated Smad3 induced by TGF-β interacted with the cofactor H-Ras and bound to the promoter of PRDM16, downregulating its transcription. Tubular-specific knockout of Prdm16 promoted renal fibrosis in models of unilateral ureteral occlusion (UUO) and unilateral ischemia-reperfusion injury (UIRI) by exacerbating mitochondrial dysfunction. In vitro, PRDM16 blocked TGF-β–induced mitochondrial injury and lipid deposition by upregulating peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). Delivery of the exogenous PRDM16 gene preserved renal function and ameliorated the progression of renal fibrosis by protecting mitochondrial function. We report PRDM16 as a potential downstream target of TGF-β signaling that attenuates renal fibrosis by safeguarding tubular mitochondrial function.

Authors

Qian Yuan, Ben Tang, Yuting Zhu, Chao Wan, Yaru Xie, Yajuan Xie, Cheng Wan, Hua Su, Youhua Liu, Chun Zhang

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Figure 7

Renal injection with PRDM16 overexpressing lentivirus attenuated mitochondrial dysfunction and interstitial fibrosis in the UIRI model.

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Renal injection with PRDM16 overexpressing lentivirus attenuated mitocho...
(A) Schematic diagram of the UIRI model with lentivirus injection; (B and C) Serum creatinine and BUN levels in each group (n = 6 or 8); (D) Representative immunohistochemical staining images of PRDM16. Scale bar: 20 μm; (E) Ratio of the PRDM16-positive area to the total area (n = 6 or 8); (F) Relative mRNA level of PRDM16 in the renal cortex of each group (n = 6 or 8); (G) Representative immunohistochemical staining images of PGC-1α. Scale bar: 20 μm; (H) Ratio of the PGC-1α–positive area to the total area (n = 6 or 8); (I) Relative mRNA level of Ppargc1a in the renal cortex of each group (n = 6 or 8); (J) Relative mRNA level of TFAM in the renal cortex of each group (n = 6 or 8); (K) Citrate synthase activity of each group (n = 6 or 8); (L) Representative images of Oil Red O staining. Scale bar: 20 μm; (M–O) Representative Western blotting (M) (n = 6 or 8) and quantification of α-SMA (N) and Fibronectin (O) with kidney pole cortex lysates; (P–R) Representative images (Q) of IHC staining of α- SMA and Fibronectin, and Masson-trichrome staining and quantification of the α-SMA-positive area (P), the Fibronectin-positive area and the fibrotic area (R) (n = 6 or 8). Scale bar: 20 μm. Data are mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001; †P < 0.05, ††P < 0.01, †††P < 0.001. Asterisks indicate comparison to sham or control group. Crosses indicate comparison to TGF-β or UUO/UIRI/FA groups. One-way ANOVA followed by Tukey’s post test (B, C, E, F, H–K, N–P, and R).