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Protective Role for Tissue Inhibitor of Metalloproteinase-4, a Novel Peroxisome Proliferator-Activated Receptor-? Target Gene, in Smooth Muscle in Deoxycorticosterone Acetate-Salt Hypertension.

ABSTRACT: Loss of peroxisome proliferator-activated receptor-? (PPAR?) function causes hypertension, whereas its activation lowers blood pressure. Evidence suggests that these effects may be attributable to PPAR? activity in the vasculature. However, the specific transcriptional targets of PPAR? in vessels remain largely unidentified. In this study, we examined the role of smooth muscle PPAR? during salt-sensitive hypertension and investigated its transcriptional targets and functional effect. Transgenic mice expressing dominant-negative PPAR? (S-P467L) in smooth muscle cells were more prone to deoxycorticosterone acetate-salt-induced hypertension and mesenteric arterial dysfunction compared with nontransgenic controls. Despite similar morphometry at baseline, vascular remodeling in conduit and small arteries was enhanced in S-P467L after deoxycorticosterone acetate-salt treatment. Gene expression profiling in aorta and mesenteric arteries revealed significantly decreased expression of tissue inhibitor of metalloproteinase-4 (TIMP-4) in S-P467L. Expression of TIMP-4 was increased by deoxycorticosterone acetate-salt treatment, but this increase was ablated in S-P467L. Interference with PPAR? activity either by treatment with a PPAR? inhibitor, GW9662, or by expressing P467L PPAR? markedly suppressed TIMP-4 in primary smooth muscle cells. PPAR? binds to a PPAR response element (PPRE) in chromatin close to the TIMP-4 gene in smooth muscle cells, suggesting that TIMP-4 is a novel target of PPAR?. The interference with PPAR? and decrease in TIMP-4 were accompanied by an increase in total matrix metalloproteinase activity. PPAR?-mediated loss of TIMP-4 increased, whereas overexpression of TIMP-4 decreased smooth muscle cell migration in a scratch assay. Our findings highlight a protective mechanism induced by PPAR? in deoxycorticosterone acetate-salt treatment, establishing a novel mechanistic link between PPAR? and TIMP-4.

SUBMITTER: Ketsawatsomkron P

PROVIDER: S-EPMC4679422 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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Protective Role for Tissue Inhibitor of Metalloproteinase-4, a Novel Peroxisome Proliferator-Activated Receptor-γ Target Gene, in Smooth Muscle in Deoxycorticosterone Acetate-Salt Hypertension.

Ketsawatsomkron Pimonrat P Keen Henry L HL Davis Deborah R DR Lu Ko-Ting KT Stump Madeliene M De Silva T Michael TM Hilzendeger Aline M AM Grobe Justin L JL Faraci Frank M FM Sigmund Curt D CD

Hypertension (Dallas, Tex. : 1979) 20151123 1

Loss of peroxisome proliferator-activated receptor-γ (PPARγ) function causes hypertension, whereas its activation lowers blood pressure. Evidence suggests that these effects may be attributable to PPARγ activity in the vasculature. However, the specific transcriptional targets of PPARγ in vessels remain largely unidentified. In this study, we examined the role of smooth muscle PPARγ during salt-sensitive hypertension and investigated its transcriptional targets and functional effect. Transgenic ...[more]

PMID: 26597823

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Project description:Peroxisome proliferator-activated receptor-? (PPAR?) plays an important role in the vasculature; however, the role of PPAR? in abdominal aortic aneurysms (AAA) is not well understood. We hypothesized that PPAR? in smooth muscle cells (SMCs) attenuates the development of AAA. We also investigated PPAR?-mediated signaling pathways that may prevent the development of AAA.We determined whether periaortic application of CaCl(2) renders vascular SMC-selective PPAR? knockout (SMPG KO) mice more susceptible to destruction of normal aortic wall architecture.There is evidence of increased vessel dilatation in the abdominal aorta 6 weeks after 0.25M periaortic CaCl(2) application in SMPG KO mice compared with littermate controls (1.4 ± 0.3 mm [n = 8] vs 1.1 ± 0.2 mm [n = 7]; P = .000119). Results from SMPG KO mice indicate medial layer elastin degradation was greater 6 weeks after abluminal application of CaCl(2) to the abdominal aorta (P < .01). Activated cathepsin S, a potent elastin-degrading enzyme, was increased in SMPG KO mice vs wild-type controls. To further identify a role of PPAR? signaling in reducing the development of AAA, we demonstrated that adenoviral-mediated PPAR? overexpression in cultured rat aortic SMCs decreases (P = .022) the messenger RNA levels of cathepsin S. In addition, a chromatin immunoprecipitation assay detected PPAR? bound to a peroxisome proliferator-activated receptor response element (PPRE) -141 to -159 bp upstream of the cathepsin S gene sequence in mouse aortic SMCs. Also, adenoviral-mediated PPAR? overexpression and knockdown in cultured rat aortic SMCs decreases (P = .013) and increases (P = .018) expression of activated cathepsin S. Finally, immunohistochemistry demonstrated a greater inflammatory infiltrate in SMPG KO mouse aortas, as evidenced by elevations in F4/80 and tumor necrosis factor-? expression.In this study, we identify PPAR? as an important contributor in attenuating the development of aortic aneurysms by demonstrating that loss of PPAR? in vascular SMCs promotes aortic dilatation and elastin degradation. Thus, PPAR? activation may be potentially promising medical therapy in reducing the risk of AAA progression and rupture.

Dataset Information

Protective Role for Tissue Inhibitor of Metalloproteinase-4, a Novel Peroxisome Proliferator-Activated Receptor-? Target Gene, in Smooth Muscle in Deoxycorticosterone Acetate-Salt Hypertension.

Publications

Protective Role for Tissue Inhibitor of Metalloproteinase-4, a Novel Peroxisome Proliferator-Activated Receptor-γ Target Gene, in Smooth Muscle in Deoxycorticosterone Acetate-Salt Hypertension.

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