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Title: TGF-β1-elevated TRPM7 channel regulates collagen expression in hepatic stellate cells via TGF-β1/Smad pathway

Transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts plays a critical role in the development of liver fibrosis, since myofibroblasts are the key cells responsible for excessive deposition of ECM proteins. Transient receptor potential melastatin 7 (TRPM7), a non-selective cation channel with protein serine/threonine kinase activity, has been demonstrated to function in the proliferation of activated HSCs. Here, we investigated the functional role of TRPM7 in collagen deposition in activated HSC-T6 cells (a rat hepatic stellate cell line). TRPM7 mRNA and protein were measured by Real-time PCR and Western blot in TGF-β1-activated HSC-T6 cells in vitro. Results demonstrated that TRPM7 protein was dramatically increased in fibrotic human livers. Stimulation of HSC-T6 cells with TGF-β1 increased TRPM7 mRNA and protein level in a time-dependent manner. Nevertheless, TGF-β1-elicited upregulation of TRPM7 in HSC-T6 cells was abrogated by SB431542 (TGF-β1 receptor blocker) or SIS3 (inhibitor of Smad3 phosphorylation). Additionally, blockade of TRPM7 channels with non-specific TRPM7 blocker 2-APB or synthetic siRNA targeting TRPM7 attenuated TGF-β1-induced expression of myofibroblast markers, as measured by the induction of α-SMA and Col1α1. Silencing TRPM7 also increased the ratio of MMPs/TIMPs by increasing MMP-13 expression and decreasing TIMP-1 and TIMP-2 levels. Strikingly, phosphorylation of p-Smad2 and p-Smad3, associatedmore » with collagen production, was decreased in TRPM7 deficient HSC-T6 cells. These observations suggested that TGF-β1 elevates TRPM7 expression in HSCs via Smad3-dependant mechanisms, which in turn contributes Smad protein phosphorylation, and subsequently increases fibrous collagen expression. Therefore, TRPM7 may constitute a useful target for the treatment of liver fibrosis. - Highlights: • Upregulation of TRPM7 protein in human fibrotic livers • Upregulation of TRPM7 by TGF-β1 elicited Smad signaling in HSC-T6 cells • Blockade of TRPM7 decreased α-SMA and Col1α1 expressions in activated HSC-T6 cells • Silencing of TRPM7 led to collagen degradation in TGF-β1 stimulated HSC-T6 cells • TRPM7 upregulation contributes to the activation of TGF-β1/Smad pathway.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ; ; ; ; ; ;  [1] ;  [2] ;  [2] ;  [1] ;  [2] ;  [2] ;  [2] ;  [1] ;  [2] ;  [2]
  1. School of Pharmacy, Anhui Medical University, Mei Shan Road, Hefei, Anhui Province 230032 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22439880
Resource Type:
Journal Article
Resource Relation:
Journal Name: Toxicology and Applied Pharmacology; Journal Volume: 280; Journal Issue: 2; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ACTIN; COLLAGEN; FIBROSIS; GROWTH FACTORS; IN VITRO; LIVER; MESSENGER-RNA; MUSCLES; PHOSPHORYLATION; RATS; RECEPTORS; SERINE; STIMULATION; THREONINE; TIME DEPENDENCE