TY  - JOUR
A1  - Akool, El-Sayed
A1  - Doller, Anke
A1  - Müller, Roswitha
A1  - Gutwein, Paul
A1  - Xin, Cuiyan
A1  - Huwiler, Andrea
A1  - Pfeilschifter, Josef
A1  - Eberhardt, Wolfgang
T1  - Nitric oxide induces TIMP-1 expression by activating the transforming growth factor beta-Smad signaling pathway
T2  - Journal of biological chemistry
N2  - Excessive accumulation of the extracellular matrix is a hallmark of many inflammatory and fibrotic diseases, including those of the kidney. This study addresses the question whether NO, in addition to inhibiting the expression of MMP-9, a prominent metalloprotease expressed by mesangial cells, additionally modulates expression of its endogenous inhibitor TIMP-1. We demonstrate that exogenous NO has no modulatory effect on the extracellular TIMP-1 content but strongly amplifies the early increase in cytokine-induced TIMP-1 mRNA and protein levels. We examined whether transforming growth factor beta (TGFbeta), a potent profibrotic cytokine, is involved in the regulation of NO-dependent TIMP-1 expression. Experiments utilizing a pan-specific neutralizing TGFbeta antibody demonstrate that the NO-induced amplification of TIMP-1 is mediated by extracellular TGFbeta. Mechanistically, NO causes a rapid increase in Smad-2 phosphorylation, which is abrogated by the addition of neutralizing TGFbeta antisera. Similarly, the NO-dependent increase in Smad-2 phosphorylation is prevented in the presence of an inhibitor of TGFbeta-RI kinase, indicating that the NO-dependent activation of Smad-2 occurs via the TGFbeta-type I receptor. Furthermore, activation of the Smad signaling cascade by NO is corroborated by the NO-dependent increase in nuclear Smad-4 level and is paralleled by increased DNA binding of Smad-2/3 containing complexes to a TIMP-1-specific Smad-binding element (SBE). Reporter gene assays revealed that NO activates a 0.6-kb TIMP-1 gene promoter fragment as well as a TGFbeta-inducible and SBE-driven control promoter. Chromatin immunoprecipitation analysis also demonstrated DNA binding activity of Smad-3 and Smad-4 proteins to the TIMP-1-specific SBE. Finally, by enzyme-linked immunosorbent assay, we demonstrated that NO causes a rapid increase in TGFbeta(1) levels in cell supernatants. Together, these experiments demonstrate that NO by induction of the Smad signaling pathway modulates TIMP-1 expression.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/76198
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-761982
SN  - 0021-9258
VL  - 280.2005
IS  - 47
SP  - 39403
EP  - 39416
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -