Endoplasmic reticulum Ca2+ release causes Rieske iron-sulfur protein-mediated mitochondrial ROS generation in pulmonary artery smooth muscle cells.

Mitochondrial reactive oxygen species (ROS) cause Ca2+ release from the endoplasmic reticulum (ER) via ryanodine receptors (RyRs) in pulmonary artery smooth muscle cells (PASMCs), playing an essential role in hypoxic pulmonary vasoconstriction (HPV). Here we tested a novel hypothesis that hypoxia-induced RyR-mediated Ca2+ release may, in turn, promote mitochondrial ROS generation contributing to hypoxic cellular responses in PASMCs. Our data reveal that application of caffeine to elevate intracellular Ca2+ concentration ([Ca2+]i) by activating RyRs results in a significant increase in ROS production in cytosol and mitochondria of PASMCs. Norepinephrine to increase [Ca2+]i due to the opening of inositol 1,4,5-triphosphate receptors (IP3Rs) produces similar effects. Exogenous Ca2+ significantly increases mitochondrial-derived ROS generation as well. Ru360 also inhibits the hypoxic ROS production. The RyR antagonist tetracaine or RyR2 gene knockout (KO) suppresses hypoxia-induced responses as well. Inhibition of mitochondrial Ca2+ uptake with Ru360 eliminates N- and Ca2+-induced responses. RISP KD abolishes the hypoxia-induced ROS production in mitochondria of PASMCs. Rieske iron-sulfur protein (RISP) gene knockdown (KD) blocks caffeine- or NE-induced ROS production. Taken together, these findings have further demonstrated that ER Ca2+ release causes mitochondrial Ca2+ uptake and RISP-mediated ROS production; this novel local ER/mitochondrion communication-elicited, Ca2+-mediated, RISP-dependent ROS production may play a significant role in hypoxic cellular responses in PASMCs.

Dong D ，Hao Q ，Zhang P ，Wang T ，Han F ，Liang X ，Fei Z ... -  《-》

Important Role of Sarcoplasmic Reticulum Ca(2+) Release via Ryanodine Receptor-2 Channel in Hypoxia-Induced Rieske Iron-Sulfur Protein-Mediated Mitochondrial Reactive Oxygen Species Generation in Pulmonary Artery Smooth Muscle Cells.

Yang Z ，Song T ，Truong L ，Reyes-García J ，Wang L ，Zheng YM ，Wang YX ... -  《-》

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

Yadav VR ，Song T ，Joseph L ，Mei L ，Zheng YM ，Wang YX ... -  《-》

Cross Talk Between Mitochondrial Reactive Oxygen Species and Sarcoplasmic Reticulum Calcium in Pulmonary Arterial Smooth Muscle Cells.

Song T ，Zheng YM ，Wang YX 《Advances in Experimental Medicine and Biology》

Primary role of mitochondrial Rieske iron-sulfur protein in hypoxic ROS production in pulmonary artery myocytes.

This study was designed to determine whether: (1) hypoxia could directly affect ROS production in isolated mitochondria and mitochondrial complex III from pulmonary artery smooth muscle cells (PASMCs) and (2) Rieske iron-sulfur protein in complex III might mediate hypoxic ROS production, leading to hypoxic pulmonary vasoconstriction (HPV). Our data, for the first time, demonstrate that hypoxia significantly enhances ROS production, measured by the standard ROS indicator dichlorodihydrofluorescein/diacetate, in isolated mitochondria from PASMCs. Studies using the newly developed, specific ROS biosensor pHyPer have found that hypoxia increases mitochondrial ROS generation in isolated PASMCs as well. Hypoxic ROS production has also been observed in isolated complex III. Rieske iron-sulfur protein silencing using siRNA abolishes the hypoxic ROS formation in isolated PASM complex III, mitochondria, and cells, whereas Rieske iron-sulfur protein overexpression produces the opposite effect. Rieske iron-sulfur protein silencing inhibits the hypoxic increase in [Ca(2+)](i) in PASMCs and hypoxic vasoconstriction in isolated PAs. These findings together provide novel evidence that mitochondria are the direct hypoxic targets in PASMCs, in which Rieske iron-sulfur protein in complex III may serve as an essential, primary molecule that mediates the hypoxic ROS generation, leading to an increase in intracellular Ca(2+) in PASMCs and HPV.

Korde AS ，Yadav VR ，Zheng YM ，Wang YX ... -  《-》