Reduction of Mitochondria-Endoplasmic Reticulum Interactions by Acetylcholine Protects Human Umbilical Vein Endothelial Cells From Hypoxia/Reoxygenation Injury.

Abstract

OBJECTIVE:

We explored the role of endoplasmic reticulum (ER)-mitochondria Ca(2+) cross talk involving voltage-dependent anion channel-1 (VDAC1)/glucose-regulated protein 75/inositol 1,4,5-trisphosphate receptor 1 complex and mitofusin 2 in endothelial cells during hypoxia/reoxygenation (H/R), and investigated the protective effects of acetylcholine.

APPROACH AND RESULTS:

Acetylcholine treatment during reoxygenation prevented intracellular and mitochondrial Ca(2+) increases and alleviated ER Ca(2+) depletion during H/R in human umbilical vein endothelial cells. Consequently, acetylcholine enhanced mitochondrial membrane potential and inhibited proapoptotic cascades, thereby reducing cell death and preserving endothelial ultrastructure. This effect was likely mediated by the type-3 muscarinic acetylcholine receptor and the phosphatidylinositol 3-kinase/Akt pathway. In addition, interactions among members of the VDAC1/glucose-regulated protein 75/inositol 1,4,5-trisphosphate receptor 1 complex were increased after H/R and were associated with mitochondrial Ca(2+) overload and cell death. Inhibition of the partner of the Ca(2+) channeling complex (VDAC1 siRNA) or a reduction in ER-mitochondria tethering (mitofusin 2 siRNA) prevented the increased protein interaction within the complex and reduced mitochondrial Ca(2+) accumulation and subsequent endothelial cell death after H/R. Intriguingly, acetylcholine could modulate ER-mitochondria Ca(2+) cross talk by inhibiting the VDAC1/glucose-regulated protein 75/inositol 1,4,5-trisphosphate receptor 1 complex and mitofusin 2 expression. Phosphatidylinositol 3-kinase siRNA diminished acetylcholine-mediated inhibition of mitochondrial Ca(2+) overload and VDAC1/glucose-regulated protein 75/inositol 1,4,5-trisphosphate receptor 1 complex formation induced by H/R.

CONCLUSIONS:

Our data suggest that ER-mitochondria interplay plays an important role in reperfusion injury in the endothelium and may be a novel molecular target for endothelial protection. Acetylcholine attenuates both intracellular and mitochondrial Ca(2+) overload and protects endothelial cells from H/R injury, presumably by disrupting the ER-mitochondria interaction.

• Authors: Xi He, Xue-Yuan Bi, Xing-Zhu Lu, Ming Zhao, Xiao-Jiang Yu, Lei Sun, Man Xu, W Gil Wier, Wei-Jin Zang
• Journal: Arteriosclerosis, thrombosis, and vascular biology (Arterioscler Thromb Vasc Biol) Vol. 35 Issue 7 Pg. 1623-34 (Jul 2015) ISSN: 1524-4636 [Electronic] United States
• PMID: 25977565 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2015 American Heart Association, Inc.

Chemical References

• Elafin
• HSP70 Heat-Shock Proteins
• Inositol 1,4,5-Trisphosphate Receptors
• Membrane Proteins
• Mitochondrial Proteins
• PI3 protein, human
• Receptors, Muscarinic
• VDAC1 protein, human
• glucose-regulated proteins
• Nitric Oxide Synthase Type III
• Voltage-Dependent Anion Channel 1
• Proto-Oncogene Proteins c-akt
• GTP Phosphohydrolases
• MFN2 protein, human
• Acetylcholine
• Calcium

Topics

• Acetylcholine (pharmacology)
• Apoptosis (drug effects)
• Calcium (metabolism)
• Down-Regulation
• Elafin (metabolism)
• Endoplasmic Reticulum (drug effects, metabolism)
• GTP Phosphohydrolases (metabolism)
• HSP70 Heat-Shock Proteins (metabolism)
• Human Umbilical Vein Endothelial Cells (drug effects, metabolism)
• Humans
• Hypoxia (metabolism)
• Inositol 1,4,5-Trisphosphate Receptors (metabolism)
• Membrane Potential, Mitochondrial
• Membrane Proteins (metabolism)
• Mitochondria (drug effects, metabolism)
• Mitochondrial Proteins (metabolism)
• Nitric Oxide Synthase Type III (metabolism)
• Proto-Oncogene Proteins c-akt (metabolism)
• Receptors, Muscarinic (metabolism)
• Signal Transduction
• Voltage-Dependent Anion Channel 1 (metabolism)