Proteomic landscape of TGF-β1-induced fibrogenesis in renal fibroblasts

Transforming growth factor-β1 (TGF-β1) plays a premier role in fibrosis. To understand the molecular events underpinning TGF-β1-induced fibrogenesis, we examined the proteomic profiling of a TGF-β1-induced in vitro model of fibrosis in NRK-49F normal rat kidney fibroblasts. Mass spectrometric analysis indicated that 628 cell-lysate proteins enriched in 44 cellular component clusters, 24 biological processes and 27 molecular functions were regulated by TGF-β1. Cell-lysate proteins regulated by TGF-β1 were characterised by increased ribosomal proteins and dysregulated proteins involved in multiple metabolic pathways, including reduced Aldh3a1 and induced Enpp1 and Impdh2, which were validated by enzyme-linked immunosorbent assays (ELISA). In conditioned media, 62 proteins enriched in 20 cellular component clusters, 40 biological processes and 7 molecular functions were regulated by TGF-β1. Secretomic analysis and ELISA uncovered dysregulated collagen degradation regulators (induced PAI-1 and reduced Mmp3), collagen crosslinker (induced Plod2), signalling molecules (induced Ccn1, Ccn2 and Tsku, and reduced Ccn3) and chemokines (induced Ccl2 and Ccl7) in the TGF-β1 group. We conclude that TGF-β1-induced fibrogenesis in renal fibroblasts is an intracellular metabolic disorder and is inherently coupled with inflammation mediated by chemokines. Proteomic profiling established in this project may guide development of novel anti-fibrotic therapies in a network pharmacology approach.