Complement factor B in high glucose–induced podocyte injury and diabetic kidney disease
Qingmiao Lu, Qing Hou, Kai Cao, Xiaoli Sun, Yan Liang, Mengru Gu, Xian Xue, Allan Zijian Zhao, Chunsun Dai
Qingmiao Lu, Qing Hou, Kai Cao, Xiaoli Sun, Yan Liang, Mengru Gu, Xian Xue, Allan Zijian Zhao, Chunsun Dai
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Research Article Inflammation Nephrology

Complement factor B in high glucose–induced podocyte injury and diabetic kidney disease

Abstract

The role and mechanisms for upregulating complement factor B (CFB) expression in podocyte dysfunction in diabetic kidney disease (DKD) are not fully understood. Here, analyzing Gene Expression Omnibus GSE30528 data, we identified genes enriched in mTORC1 signaling, CFB, and complement alternative pathways in podocytes from patients with DKD. In mouse models, podocyte mTOR complex 1 (mTORC1) signaling activation was induced, while blockade of mTORC1 signaling reduced CFB upregulation, alternative complement pathway activation, and podocyte injury in the glomeruli. Knocking down CFB remarkably alleviated alternative complement pathway activation and DKD in diabetic mice. In cultured podocytes, high glucose treatment activated mTORC1 signaling, stimulated STAT1 phosphorylation, and upregulated CFB expression, while blockade of mTORC1 or STAT1 signaling abolished high glucose–upregulated CFB expression. Additionally, high glucose levels downregulated protein phosphatase 2Acα (PP2Acα) expression, while PP2Acα deficiency enhanced high glucose–induced mTORC1/STAT1 activation, CFB induction, and podocyte injury. Taken together, these findings uncover a mechanism by which CFB mediates podocyte injury in DKD.

Authors

Qingmiao Lu, Qing Hou, Kai Cao, Xiaoli Sun, Yan Liang, Mengru Gu, Xian Xue, Allan Zijian Zhao, Chunsun Dai

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Figure 2

CFB knockdown attenuates podocyte injury and DKD in STZ-induced diabetic mice.

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CFB knockdown attenuates podocyte injury and DKD in STZ-induced diabetic...
(A) Western blot assay showing CFB expression in mouse livers and kidneys after CFB shRNA (shCFB) injection. shNC, scrambled shRNA. (B) The strategy for establishing a mouse model of DKD and the injection of shCFB. (C) UACR among different groups. #P < 0.05, *P < 0.05, n = 4–7. (D) Representative immunohistochemical staining images showing the abundance of CFB, C3d, C5b-9, and C5aR in glomerulus among different groups. Scale bar: 20 μm. (E) Representative PAS staining and representative immunofluorescence staining images for diabetic kidney injury, WT1, and nephrin among different groups. Scale bar: 20 μm. (F) Representative TEM images. Scale bar: 400 nm (above). Scale bar: 1 μm (below). (G–J) Quantitative analyses of CFB, C3d, C5b-9, and C5aR-staining per glomerulus among different groups. #P < 0.05, *P < 0.05, n = 4–7. (K) The graphs showing the kidney/body weight ratio among different groups. #P < 0.05, *P < 0.05, n = 4–7. (L and M) Quantitative analyses of glomerular area (L) and WT1-positive podocytes per glomerulus (M) among different groups. #P < 0.05, *P < 0.05, n = 4–7. Data are expressed as the mean ± SEM. Comparison between the groups was performed using 1-way ANOVA followed by the Tukey test.