Clinical and experimental nephrology
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Clin. Exp. Nephrol. · Sep 2004
Role of mitogen-activated protein kinase in the regulation of transforming growth factor-beta-induced fibronectin accumulation in cultured renal interstitial fibroblasts.
In diabetic nephropathy, tubulointerstitial fibrosis is an important component of renal injury. Transforming growth factor (TGF)-beta is a key cytokine that is involved in the pathogenesis of tubulointerstitial fibrosis. However, signal transduction cascades of TGF-beta under high-glucose conditions remain to be clarified. We undertook this study to elucidate whether mitogen-activated protein (MAP) kinase and Smad proteins were involved in TGF-beta-induced fibronectin (FN) production under high glucose in NRK fibroblasts. ⋯ NRK fibroblasts exposed to high glucose demonstrated increased TGF-beta1-induced p38 MAP kinase activation. The FN synthesis induced by high glucose and TGF-beta1 was not affected by the Smads pathway and was not due to increased osmolarity. The enhanced activation of p38 MAP kinase may contribute to the altered fibroblast phenotype that leads to progressive diabetic nephropathy.