Protein complex formation with heat shock protein 90 in chronic hypoxia-induced pulmonary hypertension in newborn piglets.

Fike CD, Pfister SL, Slaughter JC, Kaplowitz MR, Zhang Y, Zeng H, Frye NR, Aschner JL
Am J Physiol Heart Circ Physiol. 2010 299 (4): H1190-204

PMID: 20693398 · PMCID: PMC2957352 · DOI:10.1152/ajpheart.01207.2009

Aberrant interactions between heat shock protein (Hsp)90 and its client proteins could contribute to pulmonary hypertension. We tested the hypotheses that 1) the interaction between Hsp90 and its known client protein, endothelial nitric oxide synthase (eNOS), is impaired in pulmonary resistance arteries (PRAs) from piglets with pulmonary hypertension caused by exposure to 3 or 10 days of hypoxia and 2) Hsp90 interacts with the prostanoid pathway proteins prostacyclin synthase (PGIS) and/or thromboxane synthase (TXAS). We also determined whether Hsp90 antagonism with geldanamycin alters the agonist-induced synthesis of prostacyclin and thromboxane or alters PRA responses to these prostaglandin metabolites. Compared with normoxic piglets, less eNOS coimmunoprecipitated with Hsp90 in PRAs from hypoxic piglets. Despite reduced Hsp90-eNOS interactions, dilation to ACh was enhanced in geldanamycin-treated PRAs from hypoxic, but not normoxic, piglets. In PRAs from all groups of piglets, PGIS and TXAS coimmunoprecipitated with Hsp90. Geldanamycin reduced the ACh-induced synthesis of prostacyclin and thromboxane and altered responses to the thromboxane mimetic U-46619 in PRAs from all groups. Although geldanamycin enhanced responses to prostacyclin in PRAs from both groups of hypoxic piglets, geldanamycin had no effect on prostacyclin responses in PRAs from either group of normoxic piglets. Our findings indicate that Hsp90 influences both prostanoid and eNOS signaling in the pulmonary circulation of newborn piglets and that the impact of pharmacological inhibition of Hsp90 on these signaling pathways is altered during exposure to chronic hypoxia.

MeSH Terms (18)

Animals Animals, Newborn Benzoquinones Cytochrome P-450 Enzyme System Disease Models, Animal Enzyme Inhibitors HSP90 Heat-Shock Proteins Hypertension, Pulmonary Hypoxia Intramolecular Oxidoreductases Lactams, Macrocyclic Nitric Oxide Synthase Nitric Oxide Synthase Type III Pulmonary Artery Signal Transduction Swine Thromboxane-A Synthase Vascular Resistance

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