Activation of hypoxia-inducible factor-1 in pulmonary arterial smooth muscle cells by endothelin-1.

Abstract

Numerous cellular responses to hypoxia are mediated by the transcription factor hypoxia-inducible factor-1 (HIF-1). HIF-1 plays a central role in the pathogenesis of hypoxic pulmonary hypertension. Under certain conditions, HIF-1 may utilize feedforward mechanisms to amplify its activity. Since hypoxia increases endothelin-1 (ET-1) levels in the lung, we hypothesized that during moderate, prolonged hypoxia ET-1 might contribute to HIF-1 signaling in pulmonary arterial smooth muscle cells (PASMCs). Primary cultures of rat PASMCs were treated with ET-1 or exposed to moderate, prolonged hypoxia (4% O(2) for 60 h). Levels of the oxygen-sensitive HIF-1α subunit and expression of HIF target genes were increased in both hypoxic cells and cells treated with ET-1. Both hypoxia and ET-1 also increased HIF-1α mRNA expression and decreased mRNA and protein expression of prolyl hydroxylase 2 (PHD2), which is the protein responsible for targeting HIF-1α for O(2)-dependent degradation. The induction of HIF-1α by moderate, prolonged hypoxia was blocked by BQ-123, an antagonist of ET-1 receptor subtype A. The effects of ET-1 were mediated by increased intracellular calcium, generation of reactive oxygen species, and ERK1/2 activation. Neither ET-1 nor moderate hypoxia induced the expression of HIF-1α or HIF target genes in aortic smooth muscle cells. These results suggest that ET-1 induces a PASMC-specific increase in HIF-1α levels by upregulation of HIF-1α synthesis and downregulation of PHD2-mediated degradation, thereby amplifying the induction of HIF-1α in PASMCs during moderate, prolonged hypoxia.

• Authors: Sarah Pisarcik, Julie Maylor, Wenju Lu, Xin Yun, Clark Undem, J T Sylvester, Gregg L Semenza, Larissa A Shimoda
• Journal: American journal of physiology. Lung cellular and molecular physiology (Am J Physiol Lung Cell Mol Physiol) Vol. 304 Issue 8 Pg. L549-61 (Apr 15 2013) ISSN: 1522-1504 [Electronic] United States
• PMID: 23418090 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Endothelin A Receptor Antagonists
• Endothelin-1
• Hif1a protein, rat
• Hypoxia-Inducible Factor 1, alpha Subunit
• Peptides, Cyclic
• RNA, Messenger
• Reactive Oxygen Species
• Procollagen-Proline Dioxygenase
• Egln1 protein, rat
• Hypoxia-Inducible Factor-Proline Dioxygenases
• Extracellular Signal-Regulated MAP Kinases
• cyclo(Trp-Asp-Pro-Val-Leu)
• Calcium

Topics

• Animals
• Base Sequence
• Calcium (metabolism)
• Cell Hypoxia (genetics, physiology)
• Cells, Cultured
• Endothelin A Receptor Antagonists
• Endothelin-1 (pharmacology)
• Extracellular Signal-Regulated MAP Kinases (metabolism)
• Gene Expression (drug effects)
• Hypoxia-Inducible Factor 1, alpha Subunit (genetics, metabolism)
• Hypoxia-Inducible Factor-Proline Dioxygenases
• Male
• Myocytes, Smooth Muscle (drug effects, metabolism)
• Peptides, Cyclic (pharmacology)
• Procollagen-Proline Dioxygenase (genetics, metabolism)
• Pulmonary Artery (cytology, drug effects, metabolism)
• RNA, Messenger (genetics, metabolism)
• Rats
• Rats, Wistar
• Reactive Oxygen Species (metabolism)