Regulation of the rat interstitial collagenase promoter by IL‐1β, c‐Jun, and ras‐dependent signaling in growth plate chondrocytes

Abstract

In an attempt to better define molecular influences on rat interstitial collagenase gene expression in cartilage, the promoter function was characterized using transient transfection assay, electrophoresis mobility shift assay, and genetic analysis in isolated growth plate chondrocytes. Data from 5'-flanking deletion and selected mutations suggest that multiple cis elements in both the proximal and distal regions of the promoter were important in the regulation of promoter activity. A proximal tumor response element (TRE) was shown to be necessary for basal and interleukin (IL)-1 beta-inducible reporter gene activity. Cells stimulated by IL-1 beta (1 ng/ml; 18 h) had elevated TRE binding activity, and one of the factors involved was identified as the nuclear protein, c-Jun. Indeed, c-Jun directed antisense oligonucleotides reduced rat interstitial collagenase mRNA. A sense oligonucleotide was ineffective. Regulation of promoter activity was susceptible to Ras-dependent signaling as expression of dominant negative mutant of Ras kinase (pZIP-RasN17) reduced reporter gene activity. In a comparison of proximal promoter reporter plasmid activity between proliferative and hypertrophic cells, inhibition of Ras-dependent signaling was less effective in the later cell type. This study suggests that the activation of nuclear binding proteins that bind TRE may be a common event with IL-1 beta regulation. Moreover, these data suggest that the regulation of rat interstitial collagenase gene expression is a combinatorial process and multiple cis-acting regulatory sites may interact to exert different effects dependent on the stage of chondrocyte differentiation.

Tyrosine phosphatase SHP‐2 regulates IL‐1 signaling in fibroblasts through focal adhesions

“…Importance of the adaptor function of SHP-2 in signaling to the ERK pathway IL-1b activates the Ras-ERK pathway (Grumbles et al, 1997;O'Neill, 2000), but the proteins that integrate IL-1b signals with ERK activation at focal adhesions are undefined. To delineate the signaling Fig.…”

Molecular mechanism of the reversibility of hepatic fibrosis: With special reference to the role of matrix metalloproteinases

“…Fos and Jun proteins contribute to induce MMP‐1 gene transcription by their binding to proximal activated protein (AP)‐1 sites of the promoter in fibroblasts and immortalized cells. 58–60 In addition to the role of AP‐1, Vincenti et al recently reported a role of NF‐κB in the induction of rabbit MMP‐1‐ in IL‐1‐treated synovial fibroblasts. They reported that a dorsal‐like site located at nucleotide –3029 as well as at the AP‐1 site at – 77 in the rabbit MMP‐1 promoter is required for IL‐1β responsiveness of MMP‐1 gene expression, and that the p50 NF‐κB subunit binds to this dorsal‐like site by using an electric mobility shift assay.…”

Novel radioprotectant drugs for sparing radiation‐induced damage to the physis

“…The radioprotection of growth plate chondrocytes by IL-1a might be related to its known effects on proliferation, differentiation and matrix synthesis of growth plate chondrocytes in tissue culture (Horan et al 1996, Grumbles et al 1997, Kawashima-Ohya et al 1998. IL-1a has been shown to target resting zone cells and to promote alkaline phosphatase secretion (Horan et al 1996).…”