Tenascin-C promotes the proliferation and fibrosis of mesangial cells in diabetic nephropathy through the β-catenin pathway

摘要

Objective To mechanistically assess the involvement of tenascin-C (TNC) in diabetic nephropathy (DN). @@@ Methods Renal specimens from DN patients were histopathologically examined, and their TNC expression patterns were evaluated via immunohistochemistry. Additionally, the hereditarily diabetic C57BL/KsJ db/db mice were induced to develop DN via adaptive feeding, and then their renal levels of TNC and beta-catenin were assessed via western blotting and immunohistochemistry. Furthermore, the TNC and beta-catenin levels in primary rat mesangial cells (RMCs) cultured with high glucose levels were assessed via western blotting. In parallel, RMCs cultured with TNC in the presence or absence of the beta-catenin blocker ICG-001 were analyzed for their fibronectin and collagen I levels via immunostaining, and for their fibronectin, alpha-SMA, vimentin, PDGFR-beta, PCNA, and beta-catenin levels via western blotting. @@@ Results The TNC levels in the specimens were associated with the pathological classification. In these DN specimens, TNC protein was highly detected in the MCs and slightly in the tubulointerstitium. Renal TNC (P < 0.05) and beta-catenin (P < 0.001) were upregulated in db/db vs. db/m mice. High-glucose treatment upregulated TNC (P < 0.01) and beta-catenin (P < 0.05) in RMCs. TNC treatment upregulated fibronectin (P < 0.05), alpha-SMA (P < 0.01), vimentin (P < 0.05), PCNA (P < 0.05), and beta-catenin (P < 0.05) in RMCs, as assessed via western blotting. Immunohistochemical analysis confirmed the fibronectin upregulation and showed collagen I upregulation. Western-blot results also showed that levels of fibronectin (P < 0.001), alpha-SMA (P < 0.01), vimentin (P < 0.001), PCNA (P < 0.05), PDGFR-beta (P < 0.05), and beta-catenin (P < 0.01) were lower in RMCs co-treated with TNC and ICG-001 than in TNC-treated cells. Immunofluorescence analysis confirmed the decreased fibronectin level and showed that the collagen I level was also decreased by ICG-001. @@@ Conclusion TNC is upregulated in DN and induces MC proliferation and fibrosis through the beta-catenin pathway.

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