Kidney Research and Clinical Practice  2012;31(2):94-105

TGF-beta-activated kinase-1: New insights into the mechanism of TGF-beta signaling and kidney disease.

Sung Il KIM 1 ; Mary E CHOI

Affiliations

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Keywords

Chronic kidney disease; Fibrosis; Intracellular signaling; Transforming growth factor-beta1; Transforming growth factor-beta-activated kinase 1

Country

Republic of Korea

Language

English

Abstract

Transforming growth factor-beta (TGF-beta) is a multifunctional cytokine that regulates a wide variety of cellular functions, including cell growth, cellular differentiation, apoptosis, and wound healing. TGF-beta1, the prototype member of the TGF-beta superfamily, is well established as a central mediator of renal fibrosis. In chronic kidney disease, dysregulation of expression and activation of TGF-beta1 results in the relentless synthesis and accumulation of extracellular matrix proteins that lead to the development of glomerulosclerosis and tubulointerstitial fibrosis, and ultimately to end-stage renal disease. Therefore, specific targeting of the TGF-beta signaling pathway is seemingly an attractive molecular therapeutic strategy in chronic kidney disease. Accumulating evidence demonstrates that the multifunctionality of TGF-beta1 is connected with the complexity of its cell signaling networks. TGF-beta1 signals through the interaction of type I and type II receptors to activate distinct intracellular pathways. Although the Smad signaling pathway is known as a canonical pathway induced by TGF-beta1, and has been the focus of many previous reviews, importantly TGF-beta1 also induces various Smad-independent signaling pathways. In this review, we describe evidence that supports current insights into the mechanism and function of TGF-beta-activated kinase 1 (TAK1), which has emerged as a critical signaling molecule in TGF-beta-induced Smad-independent signaling pathways. We also discuss the functional role of TAK1 in mediating the profibrotic effects of TGF-beta1.