Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China.
Division of Cancer Research and Training, Department of Internal Medicine, Charles Drew University of Medicine and Science, Los Angeles, CA 90059, U.S.A.
Biosci Rep. 2019 Dec 20;39(12). doi: 10.1042/BSR20192414.
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.
线粒体活性氧（ROS）通过肺动脉平滑肌细胞（PASMC）中的兰尼碱受体（RyRs）引起内质网（ER）中的 Ca2+释放，在低氧性肺血管收缩（HPV）中发挥重要作用。在这里，我们检验了一个新的假设，即低氧诱导的 RyR 介导的 Ca2+释放可能反过来促进线粒体 ROS 的产生，从而导致 PASMC 中的低氧细胞反应。我们的数据显示，应用咖啡因通过激活 RyRs 来提高细胞内 Ca2+浓度 ([Ca2+]i)，导致 PASMC 胞质和线粒体中 ROS 产生显著增加。去甲肾上腺素通过打开三磷酸肌醇受体（IP3Rs）增加 [Ca2+]i 也会产生类似的效果。外源性 Ca2+也显著增加线粒体衍生的 ROS 生成。Ru360 也抑制低氧 ROS 产生。RyR 拮抗剂四卡因或 RyR2 基因敲除 (KO) 也抑制低氧诱导的反应。用 Ru360 抑制线粒体 Ca2+摄取消除了 N 和 Ca2+诱导的反应。RISP KD 消除了 PASMC 线粒体中低氧诱导的 ROS 产生。 Rieske 铁硫蛋白 (RISP) 基因敲低 (KD) 阻断咖啡因或 NE 诱导的 ROS 产生。总之，这些发现进一步表明 ER Ca2+释放导致线粒体 Ca2+摄取和 RISP 介导的 ROS 产生；这种新型的 ER/线粒体通讯引发的、Ca2+ 介导的、RISP 依赖性的 ROS 产生可能在 PASMC 中的低氧细胞反应中发挥重要作用。
