Important role of PLC-γ1 in hypoxic increase in intracellular calcium in pulmonary arterial smooth muscle cells.

Abstract

An increase in intracellular calcium concentration ([Ca(2+)](i)) in pulmonary arterial smooth muscle cells (PASMCs) induces hypoxic cellular responses in the lungs; however, the underlying molecular mechanisms remain incompletely understood. We report, for the first time, that acute hypoxia significantly enhances phospholipase C (PLC) activity in mouse resistance pulmonary arteries (PAs), but not in mesenteric arteries. Western blot analysis and immunofluorescence staining reveal the expression of PLC-γ1 protein in PAs and PASMCs, respectively. The activity of PLC-γ1 is also augmented in PASMCs following hypoxia. Lentiviral shRNA-mediated gene knockdown of mitochondrial complex III Rieske iron-sulfur protein (RISP) to inhibit reactive oxygen species (ROS) production prevents hypoxia from increasing PLC-γ1 activity in PASMCs. Myxothiazol, a mitochondrial complex III inhibitor, reduces the hypoxic response as well. The PLC inhibitor U73122, but not its inactive analog U73433, attenuates the hypoxic vasoconstriction in PAs and hypoxic increase in [Ca(2+)](i) in PASMCs. PLC-γ1 knockdown suppresses its protein expression and the hypoxic increase in [Ca(2+)](i). Hypoxia remarkably increases inositol 1,4,5-trisphosphate (IP(3)) production, which is blocked by U73122. The IP(3) receptor (IP(3)R) antagonist 2-aminoethoxydiphenyl borate (2-APB) or xestospongin-C inhibits the hypoxic increase in [Ca(2+)](i). PLC-γ1 knockdown or U73122 reduces H(2)O(2)-induced increase in [Ca(2+)](i) in PASMCs and contraction in PAs. 2-APB and xestospongin-C produce similar inhibitory effects. In conclusion, our findings provide novel evidence that hypoxia activates PLC-γ1 by increasing RISP-dependent mitochondrial ROS production in the complex III, which causes IP(3) production, IP(3)R opening, and Ca(2+) release, playing an important role in hypoxic Ca(2+) and contractile responses in PASMCs.

• Authors: Vishal R Yadav, Tengyao Song, Leroy Joseph, Lin Mei, Yun-Min Zheng, Yong-Xiao Wang
• Journal: American journal of physiology. Lung cellular and molecular physiology (Am J Physiol Lung Cell Mol Physiol) Vol. 304 Issue 3 Pg. L143-51 (Feb 01 2013) ISSN: 1522-1504 [Electronic] United States
• PMID: 23204067 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Boron Compounds
• Estrenes
• Inositol 1,4,5-Trisphosphate Receptors
• Macrocyclic Compounds
• Methacrylates
• Oxazoles
• Pyrrolidinones
• RNA, Small Interfering
• Reactive Oxygen Species
• Rieske iron-sulfur protein
• Thiazoles
• xestospongin C
• 1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione
• myxothiazol
• Inositol 1,4,5-Trisphosphate
• 2-aminoethoxydiphenyl borate
• Phospholipase C gamma
• Electron Transport Complex III
• Calcium

Topics

• Animals
• Boron Compounds (pharmacology)
• Calcium (metabolism)
• Electron Transport Complex III (antagonists & inhibitors, genetics, metabolism)
• Estrenes (pharmacology)
• Gene Expression
• Hypoxia (genetics, metabolism, pathology)
• Inositol 1,4,5-Trisphosphate (antagonists & inhibitors, biosynthesis)
• Inositol 1,4,5-Trisphosphate Receptors (antagonists & inhibitors, metabolism)
• Lentivirus (genetics)
• Macrocyclic Compounds (pharmacology)
• Methacrylates (pharmacology)
• Mice
• Muscle Contraction (drug effects)
• Muscle, Smooth, Vascular (drug effects, metabolism, pathology)
• Myocytes, Smooth Muscle (drug effects, metabolism, pathology)
• Oxazoles (pharmacology)
• Phospholipase C gamma (antagonists & inhibitors, genetics, metabolism)
• Pulmonary Artery (drug effects, metabolism, pathology)
• Pyrrolidinones (pharmacology)
• RNA, Small Interfering (genetics)
• Reactive Oxygen Species (agonists, antagonists & inhibitors, metabolism)
• Thiazoles (pharmacology)
• Vasoconstriction (drug effects)