Article

Activation of MMP-2 in response to vascular injury is mediated by phosphatidylinositol 3-kinase-dependent-expression of MTI-MMP

Department of Surgery, University of Manitoba, Winnipeg, Manitoba, Canada
AJP Heart and Circulatory Physiology (Impact Factor: 3.84). 01/2005; 287(6):H2861-70. DOI: 10.1152/ajpheart.00230.2004
Source: PubMed

ABSTRACT

Phosphatidylinositol 3-kinase (PI3K) is required for smooth muscle cell (SMC) proliferation. This study reports that inhibitors of PI3K also prevent SMC migration and block neointimal hyperplasia in an organ culture model of restenosis. Inhibition of neointimal formation by LY-294002 was concentration and time dependent, with 10 muM yielding the maximal effect. Continuous exposure for at least the first 4-7 days of culture was essential for significant inhibition. To assess the role of matrix metalloproteinases (MMPs) in this process, we monitored MMP secretion by injured vessels in culture. Treatment with LY-294002 selectively reduced active MMP-2 in media samples according to zymography and Western blot analysis without concomitant changes in latent MMP-2. Parallel results with wortmannin indicate that MMP-2 activation is PI3K dependent. Previous research has shown a role for both furin and membrane-type 1 (MT1)-MMP (MMP-14) in the activation of MMP-2. The furin inhibitor decanoyl-Arg-Val-Lys-Arg-chloromethylketone did not prevent MMP-2 activation after balloon angioplasty. In contrast, balloon angioplasty induced a significant increase in the levels of MT1-MMP, which was suppressed by LY-294002. No change in MT1-MMP mRNA was observed with LY-294002, because equivalent amounts of this mRNA were present in both injured and noninjured vessels. These results implicate PI3K-dependent regulation of MT1-MMP protein synthesis and subsequent activation of latent MMP-2 as critical events in neointimal hyperplasia after vascular injury.

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    • "This rapid response to cell stress was consistent with the role of vimentin in protection against cytotoxic effects (Figure 1B). Also, the membrane type 1-matrix metalloproteases MMP14 and MMP2, which are functional partners during skeletal development [17] and stress response in the context of vascular injury [18], were robustly co-regulated at the transcriptional level in response to heat shock of C2C12 skeletal myotubes. Their expression level rose within 2–4 hours of insult, followed by a repression of expression levels at 8 and 24 hours (Figure 1C). "
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    ABSTRACT: Using a gene clustering strategy we determined intracellular pathway relationships within skeletal myotubes in response to an acute heat stress stimuli. Following heat shock, the transcriptome was analyzed by microarray in a temporal fashion to characterize the dynamic relationship of signaling pathways. Bioinformatics analyses exposed coordination of functionally-related gene sets, depicting mechanism-based responses to heat shock. Protein turnover-related pathways were significantly affected including protein folding, pre-mRNA processing, mRNA splicing, proteolysis and proteasome-related pathways. Many responses were transient, tending to normalize within 24 hours. In summary, we show that the transcriptional response to acute cell stress is largely transient and proteosome-centric.
    Full-text · Article · Feb 2007 · BMC Molecular Biology
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    • "The procedure was conducted with media samples recovered from organ culture after a 48-h incubation period as described previously (Zahradka et al., 2004). "
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    ABSTRACT: Peroxisome proliferator-activated receptors (PPARs) alpha and gamma are expressed in smooth muscle cells (SMCs). This study was designed to compare the effects of PPARalpha and PPARgamma on SMC proliferation and migration and to determine how they operate. Treatment of SMCs from porcine coronary artery revealed that mitogen-stimulated DNA synthesis was blocked by the PPARalpha ligand 4-chloro-6-(2,3-xylidino)-2-pyrimidinylthioacetic acid (WY14,643) and 15-deoxy-Delta(12,14) prostaglandin J(2) (15d-PGJ(2)) (a putative PPARgamma agonist) but not by the PPARgamma agonist rosiglitazone or the PPARbeta/delta ligand 2-methyl-4-((4-methyl-2-(4-trifluoromethylphenyl)-1,3-thiazol-5-yl)-methylsulfanyl)phenoxy acetic acid (GW501516). Inhibition of DNA synthesis by clofibrate and 2-(4-(2-(1-cyclohexanebutyl-3-cyclohexylureido)ethyl)phenylthio)-2-methylproprionic acid (GW7647) confirmed that SMC proliferation is affected by PPARalpha. This conclusion was supported by the fact that WY14,643 also inhibited the proliferation of H4IIE hepatoma cells (expressing only PPARalpha) but not A10 SMCs (expressing only PPARgamma1). In contrast, the effective inhibition of all cell types with 15d-PGJ(2) indicated that this compound probably operates via a PPARgamma-independent mechanism. Interestingly, rosiglitazone did not inhibit DNA synthesis of either H4IIE or A10 cells, suggesting that the activation of PPARgamma does not influence cell proliferation. Phosphorylation of cyclin-dependent kinase 2 and expression of proliferating cell nuclear antigen were inhibited by WY14,643 but not by rosiglitazone or 15d-PGJ(2), indicating that PPARalpha prevents progression into S phase. Although rosiglitazone did not block SMC proliferation, it (like WY14,643) reduced neointimal hyperplasia in vitro. This observation can be rationalized by the fact that both WY14,643 and rosiglitazone inhibit SMC migration, probably through matrix metalloproteinase 9. Our study therefore shows that selective interference with mediators of cell cycle progression and cell migration via activation of PPARs may prevent growth-related vascular diseases such as restenosis and atherosclerosis.
    Preview · Article · Jun 2006 · Journal of Pharmacology and Experimental Therapeutics
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    • "Furthermore, signaling pathways involved in the mechanism of preconditioning influence the expression or activation of MMPs; e.g., activation of protein kinase C-␨ and -␪ subtypes increases expression of MMP-2 in rat cardiac fibroblast culture (Xie et al., 2004). Phosphatidylinositol 3-ki- nase-dependent up-regulation of membrane-type 1-MMP expression modulates MMP-2 activity in injured pig coronary arteries (Zahradka et al., 2004). We have previously shown that preconditioning inhibits ischemia-induced activation and release of MMP-2 into the perfusate in rat hearts (Lalu et al., 2002); however, it is not known if MMPs and their endogenous inhibitors, the tissue inhibitors of matrix metalloproteinases (TIMPs), play a role in cardioprotection produced by preconditioning. "
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    Full-text · Article · Feb 2006 · Journal of Pharmacology and Experimental Therapeutics
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