A functional activating protein 1 (AP-1) site regulates matrix metalloproteinase 2 (MMP-2) transcription by cardiac cells through interactions with JunB-Fra1 and JunB-FosB heterodimers

Abstract

Enhanced synthesis of a specific matrix metalloproteinase, MMP-2, has been demonstrated in experimental models of ventricular failure and in cardiac extracts from patients with ischaemic cardiomyopathy. Cultured neonatal rat cardiac fibroblasts and myocytes were used to analyse the determinants of MMP-2 synthesis, including the effects of hypoxia. Culture of rat cardiac fibroblasts for 24 h in 1 % oxygen enhanced MMP-2 synthesis by more than 5-fold and augmented the MMP-2 synthetic responses of these cells to endothelin-1, angiotensin II and interleukin 1β. A series of MMP-2 promoter-luciferase constructs were used to map the specific enhancer element(s) that drive MMP-2 transcription in cardiac cells. Deletion studies mapped a region of potent transactivating function within the 91 bp region from k1433 to k1342 bp, the activity of which was increased by hypoxia. Oligonucleotides from this region were cloned in front of a heterologous simian-virus-40 (SV40) promoter and mapped the enhancer activity to a region between k1410 and k1362 bp that included a potential activating protein 1 (AP-1)-binding sequence, C −"$*% CTGACCTCC. Site-specific mutagenesis of the core TGAC sequence (indicated in bold) eliminated the transactivating activity within the k1410 to k1362 bp sequence. Electrophoretic mobility shift assays (EMSAs) using the k1410

Farnesyltransferase inhibitor SCH‐66336 downregulates secretion of matrix proteinases and inhibits carcinoma cell migration

“…Functional analysis of the gene promoters of MMP-2 and MMP-9 has allowed identification of several binding domains for transcription factors such as AP-1 and NF-B. [45][46][47] Promoters of genes encoding TIMP-1 and TIMP-2 also contain consensus sequences for AP-1. 48,49 uPA expression is regulated through AP-1 binding sites in human prostate cancer.…”

Transplantation of skeletal myoblasts secreting an IL-1 inhibitor modulates adverse remodeling in infarcted murine myocardium

“…In contrast, the levels of col ␣1(III) and TGF␤1 expression did not appear to differ between groups (␤-actin expression is shown as an internal control). Whereas IL-1 is a potentially important upstream regulator of MMP-2 and -9 (16,17), MMPs form a complex interacting network in the context of MI and are also subject to regulation by hypoxia and peptide growth factors; often through common regulatory elements such as AP-1 (16,17). Interestingly, unloading the myocardium with an LV assist device in patients with ischemic cardiomyopathy results in decreased MMP-2 levels (40), and a similar effect after SkM implantation is a possibility.…”

“…Matrix metalloproteinase (MMP) types 2 and 9 (MMP-2͞-9) are key gelatinases shown to be directly involved in post-MI ECM turnover (15). IL-1 stimulates expression of MMP-2 in ischemic cardiac fibroblasts and is a regulator of MMP-9 (16,17). No studies, however, have exploited sustained IL-1 inhibition as a means to target adverse post-MI remodeling.…”

Intronic regulation of matrix metalloproteinase-2 revealed by in vivo transcriptional analysis in ischemia

“…In contrast, the proximal Sp-1 and AP-2 sites at Ϫ90 to Ϫ50 bp are sufficient for constitutive MMP-2 transcription in astrocytoma cell lines (9). We recently demonstrated that activation and binding of activating protein-1 (AP-1) family transcription factors, specifically Fra1-JunB and FosB-JunB heterodimers, to a noncanonical AP-1 site (located at Ϫ1,392 bp relative to the start site of translation) are essential for hypoxia-induced MMP-2 transcription in cardiac fibroblasts (10).…”