The PPARγ ligand rosiglitazone attenuates hypoxia-induced endothelin signaling in vitro and in vivo

Abstract

Kang BY, Kleinhenz JM, Murphy TC, Hart CM. The PPAR␥ ligand rosiglitazone attenuates hypoxia-induced endothelin signaling in vitro and in vivo. Am J Physiol Lung Cell Mol Physiol 301: L881-L891, 2011. First published September 16, 2011 doi:10.1152/ajplung.00195.2011.-Peroxisome proliferatoractivated receptor (PPAR) ␥ activation attenuates hypoxia-induced pulmonary hypertension (PH) in mice. The current study examined the hypothesis that PPAR␥ attenuates hypoxia-induced endothelin-1 (ET-1) signaling to mediate these therapeutic effects. To test this hypothesis, human pulmonary artery endothelial cells (HPAECs) were exposed to normoxia or hypoxia (1% O 2) for 72 h and treated with or without the PPAR␥ ligand rosiglitazone (RSG, 10 M) during the final 24 h of exposure. HPAEC proliferation was measured with MTT assays or cell counting, and mRNA and protein levels of ET-1 signaling components were determined. To explore the role of hypoxiaactivated transcription factors, selected HPAECs were treated with inhibitors of hypoxia-inducible factor (HIF)-1␣ (chetomin) or nuclear factor (NF)-B (caffeic acid phenethyl ester, CAPE). In parallel studies, male C57BL/6 mice were exposed to normoxia (21% O2) or hypoxia (10% O2) for 3 wk with or without gavage with RSG (10 mg·kg Ϫ1 ·day Ϫ1 ) for the final 10 days of exposure. Hypoxia increased ET-1, endothelin-converting enzyme-1, and endothelin receptor A and B levels in mouse lung and in HPAECs and increased HPAEC proliferation. Treatment with RSG attenuated hypoxia-induced activation of HIF-1␣, NF-B activation, and ET-1 signaling pathway components. Similarly, treatment with chetomin or CAPE prevented hypoxia-induced increases in HPAEC ET-1 mRNA and protein levels. These findings indicate that PPAR␥ activation attenuates a program of hypoxia-induced ET-1 signaling by inhibiting activation of hypoxiaresponsive transcription factors. Targeting PPAR␥ represents a novel therapeutic strategy to inhibit enhanced ET-1 signaling in PH pathogenesis. pulmonary hypertension; hypoxia; peroxisome proliferator-activated receptor ␥; endothelin; endothelial cells PULMONARY HYPERTENSION (PH), defined as an elevation of the mean pulmonary artery pressure Ͼ25 mmHg at rest or 30 mmHg with exercise causes significant morbidity and mortality (13, 31). The pathogenesis of PH involves endothelial dysfunction with increased production of vasoconstrictors, e.g., endothelin-1 (ET-1), and reduced production of vasodilators, e.g., prostacyclin and nitric oxide (NO) (5,14). Despite the availability of existing PH therapies that attenuate these derangements, PH morbidity and mortality remains unacceptably high (20, 44), indicating an urgent need for novel therapeutic strategies. Recent studies indicate that the nuclear hormone receptor peroxisome proliferator-activated receptor ␥ (PPAR␥), may play an important role in the pathophysiology of PH. Treatment with thiazolidinedione (TZD) PPAR␥ ligands attenuates PH in several experimental models (6,19,27,36,39). PPAR␥ ligands not only attenuate the development ...

The MicroRNA-130/301 Family Controls Vasoconstriction in Pulmonary Hypertension

“…1), but its down-regulation may induce, rather than repress, EDN1. Specifically, prior reports have indicated that knockdown of PPAR␥ induced both PAEC proliferation and EDN1 up-regulation, whereas forced PPAR␥ expression under hypoxia attenuated these effects, suggesting a link between these factors (13). Given the up-regulation of EDN1 by miR-130/301, we investigated whether this relationship was under the control of the miR-130/301-PPAR␥ axis.…”

“…There exists, for example, a great diversity of PPAR␥ function in vascular biology beyond proliferation, from vasoconstriction to metabolism to extracellular matrix deposition (9 -12). In PH, a link has been reported between the vasoconstrictive factor EDN1 and PPAR␥ (13,14), and in turn, EDN1 is known to promote vascular smooth muscle cell contraction and increase vasoconstriction in multiple forms of rodent and human PH (3,(15)(16)(17). However, multiple molecular pathways can regulate EDN1 expression (14,18,19) and other effectors of vasomotor tone, and the comprehensive mechanisms by which these actions are coordinated in PH are still undefined.…”

Enhanced Clearance of Pseudomonas aeruginosa by Peroxisome Proliferator-Activated Receptor Gamma

“…All experiments were approved by the VAMC Institutional Animal Care and Use Committee. As previously reported (39), male C57BL/6 mice, 8 to 10 weeks of age, were treated with PIO dissolved in methylcellulose (United States Biological, Salem, MA) at 10 mg/kg body weight or with an equivalent volume of methylcellulose alone used as a vehicle control (Veh) by oral gavage. After 24 h, the mice were infected with PAO1 intranasally (40-42) with 10 8 CFU.…”

Peroxisome Proliferator-Activated Receptor γ Regulates the V-Ets Avian Erythroblastosis Virus E26 Oncogene Homolog 1/microRNA-27a Axis to Reduce Endothelin-1 and Endothelial Dysfunction in the Sickle Cell Mouse Lung

“…Furthermore, PPARg attenuates hypoxic increases in proliferative mediators (e.g., ET-1 and nicotinamide adenine dinucleotide phosphate oxidase 4), in part through inhibition of nuclear factor-kB p65 (22,32,44,45). Interestingly, mounting evidence demonstrates that pharmacological activation of PPARg attenuates pulmonary vascular cell proliferation and PH (46), whereas loss of PPARg expression or function is associated with PH (47). Taken together, these findings led us to postulate in the current study that: (1) chronic hemolysis in SCD stimulates loss of PPARg and increased expression of the proliferative mediator, ET-1, which contributes to PH pathogenesis; and (2) targeting PPARg with existing pharmacological ligands may represent a novel therapeutic approach in SCD to attenuate increases in proliferative mediators and SCD-PH pathogenesis.…”