title: Hypoxia inducible-factor1alpha regulates the metabolic shift of pulmonary hypertensive endothelial cells.
abstract: Severe pulmonary hypertension is irreversible and often fatal. Abnormal proliferation and resistance to apoptosis of endothelial cells (ECs) and hypertrophy of smooth muscle cells in this disease are linked to decreased mitochondria and preferential energy generation by glycolysis. We hypothesized this metabolic shift of pulmonary hypertensive ECs is due to greater hypoxia inducible-factor1alpha (HIF-1alpha) expression caused by low levels of nitric oxide combined with low superoxide dismutase activity. We show that cultured ECs from patients with idiopathic pulmonary arterial hypertension (IPAH-ECs) have greater HIF-1alpha expression and transcriptional activity than controls under normoxia or hypoxia, and pulmonary arteries from affected patients have increased expression of HIF-1alpha and its target carbonic anhydrase IX. Decreased expression of manganese superoxide dismutase (MnSOD) in IPAH-ECs paralleled increased HIF-1alpha levels and small interfering (SI) RNA knockdown of MnSOD, but not of the copper-zinc SOD, increased HIF-1 protein expression and hypoxia response element (HRE)-driven luciferase activity in normoxic ECs. MnSOD siRNA also reduced nitric oxide production in supernatants of IPAH-ECs. Conversely, low levels of a nitric oxide donor reduced HIF-1alpha expression in normoxic IPAH-ECs. Finally, mitochondria numbers increased in IPAH-ECs with knockdown of HIF-1alpha. These findings indicate that alterations of nitric oxide and MnSOD contribute to pathological HIF-1alpha expression and account for lower numbers of mitochondria in IPAH-ECs.
authors.affiliation: Department of Pathology, Johns Hopkins Univesity School of Medicine, Baltimore, MD, USA.
authors.forename: Iwona
authors.initials: I
authors.lastname: Fijalkowska
authors.forename: Weiling
authors.initials: W
authors.lastname: Xu
authors.forename: Suzy A A
authors.initials: SA
authors.lastname: Comhair
authors.forename: Allison J
authors.initials: AJ
authors.lastname: Janocha
authors.forename: Lori A
authors.initials: LA
authors.lastname: Mavrakis
authors.forename: Balaji
authors.initials: B
authors.lastname: Krishnamachary
authors.forename: Lijie
authors.initials: L
authors.lastname: Zhen
authors.forename: Thianzi
authors.initials: T
authors.lastname: Mao
authors.forename: Amy
authors.initials: A
authors.lastname: Richter
authors.forename: Serpil C
authors.initials: SC
authors.lastname: Erzurum
authors.forename: Rubin M
authors.initials: RM
authors.lastname: Tuder
mesh_terms: D000328:Adult; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D006976:Hypertension, Pulmonary / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D013482:Superoxide Dismutase / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D035683:MicroRNAs; D009569:Nitric Oxide; D013482:Superoxide Dismutase