Identification of calcium-independent phospholipase A2γ in mitochondria and its role in mitochondrial oxidative stress
Identification of calcium-independent phospholipase A2γ in mitochondria and its role in mitochondrial oxidative stress
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DOI：
10.1152/ajprenal.00318.2006
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发表时间：
2007-02-01
影响因子：
4.2
通讯作者：
Schnellmann, Rick G.
中科院分区：
文献类型：
--
作者：
Kinsey, Gilbert R.;McHowat, Jane;Schnellmann, Rick G.
氧化剂诱导的脂质过氧化和细胞死亡介导与缺血再灌注和炎症相关的病理学。我们之前对兔肾近端肾小管细胞 (RPTC) 的研究表明，抑制 Ca2+ 独立的磷脂酶 A(2) (iPLA(2)) 会增强氧化剂诱导的脂质过氧化和坏死，表明 iPLA2 参与磷脂修复。本研究旨在鉴定 RPTC 线粒体 PLA(2) 并确定 PLA(2) 在氧化剂诱导的线粒体功能障碍中的作用。在 Percoll 纯化的兔肾皮质线粒体 (RCM) 以及兔和人 RCM 分离的线粒体内膜组分中检测到 iPLA2 活性。免疫印迹分析和抑制剂敏感性分析表明 iPLA(2)gamma 是 RCM iPLA2 活性。 RCM iPLA2 活性在 ATP 存在下增强，并被 PKC epsilon V1-2 抑制剂阻断。 R-BEL 预处理加速了氧化剂诱导的线粒体脂质过氧化和肿胀，但 S-BEL 则不然。此外，对分离的 RCM 进行氧化处理会导致 iPLA2 γ 活性降低。这些结果表明，RCM iPLA(2) 是 iPLA(2)gamma，RCM iPLA(2)gamma 受 PKC epsilon 磷酸化调节，iPLA(2)gamma 保护 RCM 免受氧化剂诱导的脂质过氧化和功能障碍，并且保留或增强 iPLA(2)gamma 活性的策略可能具有治疗益处。
Oxidant-induced lipid peroxidation and cell death mediate pathologies associated with ischemia-reperfusion and inflammation. Our previous work in rabbit renal proximal tubular cells (RPTC) demonstrated that inhibition of Ca2+-independent phospholipase A(2) ( iPLA(2)) potentiates oxidant-induced lipid peroxidation and necrosis, implicating iPLA2 in phospholipid repair. This study was conducted to identify a RPTC mitochondrial PLA(2) and determine the role of PLA(2) in oxidant-induced mitochondrial dysfunction. iPLA2 activity was detected in Percoll-purified rabbit renal cortex mitochondria (RCM) and in isolated mitochondrial inner membrane fractions from rabbit and human RCM. Immunoblot analysis and inhibitor sensitivity profiles revealed that iPLA(2)gamma is the RCM iPLA2 activity. RCM iPLA2 activity was enhanced in the presence of ATP and was blocked by the PKC epsilon V1-2 inhibitor. Oxidant-induced mitochondrial lipid peroxidation and swelling were accelerated by pretreatment with R-BEL, but not S-BEL. Furthermore, oxidant treatment of isolated RCM resulted in decreased iPLA2 gamma activity. These results reveal that RCM iPLA(2) is iPLA(2)gamma, RCM iPLA(2)gamma is regulated by phosphorylation by PKC epsilon, iPLA(2)gamma protects RCM from oxidant-induced lipid peroxidation and dysfunction, and that a strategy to preserve or enhance iPLA(2)gamma activity may be of therapeutic benefit.