Abstract
TGF-β is a central driver of kidney fibrosis, a common pathological hallmark of chronic kidney disease (CKD). Initiation of TGF-β signaling requires not only its synthesis but also the conversion of latent TGF-β to its bioactive form. However, the mechanisms governing TGF-β activation in the kidney and their contribution to kidney fibrosis remain poorly understood. Glycoprotein A repetitions predominant (GARP) anchors latent TGF-β on the cell surface and facilitates its bioactive release. Here, we show that GARP-mediated TGF‐β activation promotes kidney fibrosis. GARP was upregulated in both human and mouse CKD kidneys, predominantly in fibroblasts, and was induced by TNF in an NF-kB-dependent fashion. In multiple mouse models of kidney fibrosis, either global or fibroblast-specific deletion of GARP significantly reduced fibrosis. Mechanistically, GARP enables sustained production of active TGF-β, thereby amplifying fibroblast stimulation. Deletion of GARP in kidney fibroblasts lowered active TGF-β levels and attenuated fibroblast activation, whereas GARP overexpression enhanced TGF-β signaling. Notably, tamoxifen-induced deletion of GARP after fibrosis onset attenuated kidney fibrosis. Together, our findings identify GARP-mediated release of active TGF‐β as a critical step in sustaining fibroblast activation during kidney fibrosis and highlight GARP as a promising therapeutic target for CKD.
Authors
Yintong Chen, Weiwei Xu, Jieli Yu, Pei Deng, Nianping Liu, Yinyin Li, Hui Zhou, Hong Zhou, Jianchuan Wang, Bo Zhao, Florian Winau, Fan Fan Hou, Yu Hu
