Abstract 10: Smooth Muscle Peroxisome Proliferator-Activated Receptor γ Plays a Critical Role in Formation and Rupture of Cerebral Aneurysms in Mice in vivo

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Robert M Starke ◽  
He Gu ◽  
Katina Wilson ◽  
Yi Chu ◽  
Nohra Chalouhi ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Inflammation ◽  
Critical Role ◽  
Cerebral Aneurysms ◽  
Dominant Negative ◽  
Peroxisome Proliferator ◽  
Nuclear Factor ◽  
Peroxisome Proliferator Activated Receptor ◽  
Aneurysm Formation ◽  
Pparγ Agonist

Background and Purpose: Vascular inflammation plays a critical role in the pathogenesis of cerebral aneurysms. Peroxisome proliferator-activated receptor γ (PPARγ) protects against vascular inflammation and atherosclerosis, whereas dominant-negative mutations in PPARγ promote atherosclerosis and vascular dysfunction. In this study, the role of PPARγ in aneurysm formation and rupture was tested. Methods: Aneurysms were induced with a combination of systemic infusion of angiotensin-II and local injection of elastase in (1) mice that received the PPARγ antagonist GW9662 or the PPARγ agonist pioglitazone, (2) mice carrying dominant-negative PPARγ mutations in endothelial or smooth muscle cells, and (3) mice that received the Cullin inhibitor MLN4924. Incidence of aneurysm formation, rupture, and mortality was quantified. Cerebral arteries were analyzed for expression of Cullin3, Kelch-like ECH-associated protein 1, nuclear factor (erythroid-derived 2)-like 2, NAD(P)H dehydrogenase (quinone)1 (NQO1), and inflammatory marker mRNAs. Results: Neither pioglitazone nor GW9662 altered the incidence of aneurysm formation. GW9662 significantly increased the incidence of aneurysm rupture, whereas pioglitazone tended to decrease the incidence of rupture. Dominant-negative endothelial-specific PPARγ did not alter the incidence of aneurysm formation or rupture. In contrast, dominant-negative smooth muscle-specific PPARγ resulted in an increase in aneurysm formation (P<0.05) and rupture (P=0.05). Dominant-negative smooth muscle-specific PPARγ, but not dominant-negative endothelial-specific PPARγ, resulted in significant decreases in expression of genes encoding Cullin3, Kelch-like ECH-associated protein 1, and nuclear factor (erythroid-derived 2)-like 2, along with significant increases in tumor necrosis factor-α, monocyte chemoattractant protein-1, chemokine (C-X-C motif) ligand 1, CD68, matrix metalloproteinase-3, -9, and -13. MLN4924 did not alter incidence of aneurysm formation, but increased the incidence of rupture (P<0.05). Conclusions: Endogenous PPARγ, specifically smooth muscle PPARγ, plays an important role in protecting from formation and rupture of experimental cerebral aneurysms in mice.

Abstract 310: Deoxycorticosterone Acetate (doca)-salt Exacerbates Hypertension and Vascular Dysfunction in Mice Expressing Dominant Negative Peroxisome Proliferator-activated Receptor-gamma (pparg) in Smooth Muscle

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Pimonrat Ketsawatsomkron ◽  
Deborah R Davis ◽  
Aline M Hilzendeger ◽  
Justin L Grobe ◽  
Curt D Sigmund
Keyword(s):  
Blood Pressure ◽  
Smooth Muscle ◽  
Transgenic Mice ◽  
Vascular Function ◽  
Vascular Dysfunction ◽  
Critical Role ◽  
Surrogate Marker ◽  
Dominant Negative ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor

PPARG, a ligand-activated transcription factor plays a critical role in the regulation of blood pressure and vascular function. We hypothesized that smooth muscle cell (SMC) PPARG protects against hypertension (HT) and resistance vessel dysfunction. Transgenic mice expressing dominant negative PPARG (S-P467L) in SMC or non-transgenic controls (NT) were implanted with DOCA pellet and allowed ad libitum access to 0.15 M NaCl for 21 days in addition to regular chow and water. Blood pressure was monitored by telemetry and mesenteric arterial (MA) function was assessed by pressurized myograph. At baseline, 24-hour mean arterial pressure (MAP) was similar between NT and S-P467L mice, while the transgenic mice were tachycardic. DOCA-salt increased MAP to a much greater degree in S-P467L mice (Δ MAP; S-P467L: +34.2±6.0, NT: +13.3±5.7, p<0.05 vs NT). Heart rate was similarly decreased in both groups after DOCA-salt. Vasoconstriction to KCl, phenylephrine and endothelin-1 did not differ in MA from DOCA-salt treated NT and S-P467L, while the response to vasopressin was significantly reduced in S-P467L after DOCA-salt (% constriction at 10-8 M, S-P467L: 31.6±5.6, NT: 46.7±3.8, p<0.05 vs NT). Urinary copeptin, a surrogate marker for arginine vasopressin was similar in both groups regardless of treatment. Vasorelaxation to acetylcholine was slightly impaired in S-P467L MA compared to NT at baseline whereas this effect was further exaggerated after DOCA-salt (% relaxation at 10-5 M, S-P467L: 56.1±8.3, NT: 79.4±5.6, p<0.05 vs NT). Vascular morphology at luminal pressure of 75 mmHg showed a significant increase in wall thickness (S-P467L: 18.7±0.8, NT: 16.0±0.4, p<0.05 vs NT) and % media/lumen (S-P467L: 8.4±0.3, NT: 7.1±0.2, p<0.05 vs NT) in S-P467L MA after DOCA-salt. Expression of tissue inhibitor of metalloproteinases (TIMP)-4 and regulator of G-protein signaling (RGS)-5 transcript were 2- and 3.5-fold increased, respectively, in MA of NT with DOCA-salt compared to NT baseline. However, this induction was markedly blunted in S-P467L MA. We conclude that interference with PPARG function in SMC leads to altered gene expression crucial for normal vascular homeostasis, thereby sensitizing the mice to the effects of DOCA-salt induced HT and vascular dysfunction.

scholarly journals Peroxisome Proliferator-Activated Receptor-γ Activates p53 Gene Promoter Binding to the Nuclear Factor-κB Sequence in Human MCF7 Breast Cancer Cells

2006 ◽  
Vol 20 (12) ◽  
pp. 3083-3092 ◽  
Author(s):  
Daniela Bonofiglio ◽  
Saveria Aquila ◽  
Stefania Catalano ◽  
Sabrina Gabriele ◽  
Maria Belmonte ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Breast Cancer Cells ◽  
Gene Promoter ◽  
P53 Gene ◽  
Nuclear Factor Κb ◽  
Peroxisome Proliferator ◽  
Nuclear Factor ◽  
Mcf7 Cells ◽  
Peroxisome Proliferator Activated Receptor ◽  
Pparγ Agonist

Abstract The aim of the present study was to provide new mechanistic insight into the growth arrest and apoptosis elicited by peroxisome proliferator-activated receptor (PPAR)γ in breast cancer cells. We ascertained that PPARγ mediates the inhibition of cycle progression in MCF7 cells exerted by the specific PPARγ agonist rosiglitazone [BRL4653 (BRL)], because this response was no longer notable in the presence of the receptor antagonist GW9662. We also provided evidence that BRL is able to up-regulate mRNA and protein levels of the tumor suppressor gene p53 and its effector p21WAF1/Cip1 in a time- and dose-dependent manner. Moreover, in transfection experiments with deletion mutants of the p53 gene promoter, we documented that the nuclear factor-κB sequence is required for the transcriptional response to BRL. Interestingly, EMSA showed that PPARγ binds directly to the nuclear factor-κB site located in the promoter region of p53, and chromatin immunoprecipitation experiments demonstrated that BRL increases the recruitment of PPARγ on the p53 promoter sequence. Next, both PPARγ and p53 were involved in the cleavage of caspases-9 and DNA fragmentation induced by BRL, given that GW9662 and an expression vector for p53 antisense blunted these effects. Our findings provide evidence that the PPARγ agonist BRL promotes the growth arrest and apoptosis in MCF7 cells, at least in part, through a cross talk between p53 and PPARγ, which may be considered an additional target for novel therapeutic interventions in breast cancer patients.

scholarly journals Failure to vasodilate in response to salt loading blunts renal blood flow and causes salt-sensitive hypertension

2020 ◽  
Author(s):  
Jing Wu ◽  
Larry N Agbor ◽  
Shi Fang ◽  
Masashi Mukohda ◽  
Anand R Nair ◽  
...  
Keyword(s):  
Blood Flow ◽  
Smooth Muscle ◽  
Renal Blood Flow ◽  
Vascular Dysfunction ◽  
Dominant Negative ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Salt Loading ◽  
Dominant Negative Mutation ◽  
Induced Hypertension

Abstract Aims Salt-sensitive (SS) hypertension is accompanied by impaired vasodilation in the systemic and renal circulation. However, the causal relationship between vascular dysfunction and salt-induced hypertension remains controversial. We sought to determine whether primary vascular dysfunction, characterized by a failure to vasodilate during salt loading, plays a causal role in the pathogenesis of SS hypertension. Methods and results Mice selectively expressing a peroxisome proliferator-activated receptor γ dominant-negative mutation in vascular smooth muscle (S-P467L) exhibited progressive SS hypertension during a 4 week high salt diet (HSD). This was associated with severely impaired vasodilation in systemic and renal vessels. Salt-induced impairment of vasodilation occurred as early as 3 days after HSD, which preceded the onset of SS hypertension. Notably, the overt salt-induced hypertension in S-P467L mice was not driven by higher cardiac output, implying elevations in peripheral vascular resistance. In keeping with this, HSD-fed S-P467L mice exhibited decreased smooth muscle responsiveness to nitric oxide (NO) in systemic vessels. HSD-fed S-P467L mice also exhibited elevated albuminuria and a blunted increase in urinary NO metabolites which was associated with blunted renal blood flow and increased sodium retention mediated by a lack of HSD-induced suppression of NKCC2. Blocking NKCC2 function prevented the salt-induced increase in blood pressure in S-P467L mice. Conclusion We conclude that failure to vasodilate in response to salt loading causes SS hypertension by restricting renal perfusion and reducing renal NO through a mechanism involving NKCC2 in a mouse model of vascular peroxisome proliferator-activated receptor γ impairment.

Abstract 331: Mutation in the PPARG Ligand Binding Domain Impairs PPARG-Mediated Turnover of the p65 Subunit of NF-kB

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Masashi Mukoda ◽  
Madeliene Stump ◽  
Pimonrat Ketsawatsomkron ◽  
Frederick W Quelle ◽  
Curt D Sigmund
Keyword(s):  
Vascular Function ◽  
Nuclear Factor Kappa B ◽  
Vascular Dysfunction ◽  
Direct Interaction ◽  
Dominant Negative ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Transfected Cells ◽  
Over Expression ◽  
Pparγ Agonist

Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand activated transcription factor regulating metabolic and vascular function. PPARγ exerts anti-inflammatory actions, and recent data suggest this may be mediated by promoting the degradation of the p65 subunit of nuclear factor kappa B (NFκB). Transgenic mice expressing dominant negative PPARγ specifically in vascular smooth muscle or endothelium exhibited exacerbated atherosclerosis but the mechanism remains unknown. We hypothesized that PPARγ mutants promote inflammation because PPARγ-mediated p65 degradation is impaired. We tested this by co-transfection of HEK293T cells with vectors encoding p65, wildtype (WT) PPARγ, or various PPARγ mutants. The level of p65 protein expression was decreased by co-expression with WT-PPARγ (0.53±0.09 vs control, n=8). Whereas, the P467L PPARγ exhibited impaired degradation of p65 (1.0±0.06, n=10), the V290M (0.36±0.1), S273A (0.37±0.06), or K268R/K293R (0.41±0.03) mutations in PPARγ preserved p65 degradation. WT PPARγ was co-precipitated with p65 in co-transfected cells suggesting the mechanism of PPARγ-mediated p65 degradation involves a direct interaction between them. Consistent with this, the interaction between p65 and P467L PPARγ was severely impaired. To assess functional interactions between PPARγ and NFκB, we employed a model of interleukin-1β (IL-1β) mediated dysfunction in aortic rings. IL-1β dose-dependently induced NFκB activity as measured by increased phospho-p65 and decreased IκBα in aorta cultured for 2 hours with IL-1β. IL-1β dose-dependently reduced acetylcholine (Ach)-induced endothelial-dependent relaxation of aortic rings (80±12 vs 39±16, 20 pg/mL vs 11±3, 100 pg/mL, %). IL-1β-mediated loss of Ach vasodilation was reduced by the PPARγ agonist rosiglitazone (1 μM, 25 hr, n=3, p<0.05), or by transgenic over-expression of WT-PPARγ specifically in endothelium (n=6, p<0.05). We conclude that 1) p65 turnover may be regulated by PPARγ and that its mutation can result in impaired p65 degradation, 2) PPARγ activity can protect against vascular dysfunction associated with NFκB activation, and 3) loss of PPARγ-mediated p65 degradation may contribute to inflammation in hypertension and atherosclerosis.

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