Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Shanghai Jiao Tong University School of Medicine (SJTUSM) and Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS), 320 Yue Yang Road, Biological Research Building A, Shanghai 200031, China.
Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Shanghai Jiao Tong University School of Medicine (SJTUSM) and Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS), 320 Yue Yang Road, Biological Research Building A, Shanghai 200031, China
Cardiovasc Res. 2015 Feb 1;105(2):192-202. doi: 10.1093/cvr/cvu256. Epub 2014 Dec 16.
Uncoupling protein 3 (UCP3), located in the mitochondrial inner membrane, is cardioprotective, but its mechanisms of preserving mitochondrial function during ischaemia/reperfusion (I/R) are not fully understood. This study investigated whether UCP3 mediates/mimics the cardioprotection of H₂O₂ preconditioning (H₂O₂PC) against I/R injury and the downstream pathway that mediates H₂O₂PC- and UCP3-afforded cardioprotection.
H₂O₂PC at 20 µM for 5 min significantly improved post-ischaemic functional recovery and reduced lactate dehydrogenase (LDH) release and infarct size with concurrently up-regulated UCP3 expressions in perfused rat hearts subjected to global no-flow I/R. These protections were blocked by UCP3 knockdown with short hairpin RNA but mimicked by UCP3 overexpression. Consistently, H₂O₂PC-attenuated I/R-induced cytosolic and mitochondrial Ca(2+) overload, Ca(2+) transient suppression, mitochondrial reactive oxygen species burst, and loss of mitochondrial inner membrane potential were reversed by UCP3 knockdown but mimicked by UCP3 overexpression. Moreover, co-immunoprecipitation assay revealed an interaction of UCP3 with the mitochondrial permeability transition pore (mPTP) component, adenine nucleotide translocator (ANT), while the cardioprotection induced by H₂O₂PC- and UCP3 overexpression in mitochondria, cardiac function, and cell survival was abolished by atractyloside, a mPTP opener binding to ANT, and partially inhibited by a PI3K/Akt inhibitor wortmannin. Furthermore, H₂O₂PC up-regulated the phosphorylation of Akt, and glycogen synthase kinase 3β was blocked by UCP3 knockdown but mimicked by UCP3 overexpression.
UCP3 mediates the cardioprotection of H₂O₂PC against I/R injury by preserving the mitochondrial function through inhibiting mPTP opening via the interaction with ANT and the PI3K/Akt pathway. Our findings reveal novel mechanisms of UCP3 in the cardioprotection.
解偶联蛋白 3（UCP3）位于线粒体内膜，具有心脏保护作用，但它在缺血/再灌注（I/R）期间维持线粒体功能的机制尚不完全清楚。本研究旨在探讨 UCP3 是否介导/模拟 H₂O₂预处理（H₂O₂PC）对 I/R 损伤的心脏保护作用，以及介导 H₂O₂PC 和 UCP3 发挥心脏保护作用的下游途径。
在进行整体无血流 I/R 的大鼠心脏中，20 μM 的 H₂O₂PC 预处理 5 分钟可显著改善缺血后功能恢复，减少乳酸脱氢酶（LDH）释放和梗死面积，同时上调 UCP3 的表达。这些保护作用被 UCP3 的短发夹 RNA 敲低所阻断，但被 UCP3 的过表达所模拟。一致地，H₂O₂PC 减弱了 I/R 诱导的细胞质和线粒体 Ca²⁺超载、Ca²⁺瞬变抑制、线粒体活性氧爆发以及线粒体内膜电位丧失，这些作用被 UCP3 的敲低所逆转，但被 UCP3 的过表达所模拟。此外，免疫共沉淀实验表明 UCP3 与线粒体通透性转换孔（mPTP）组成部分，腺嘌呤核苷酸转位酶（ANT）相互作用，而 H₂O₂PC 和 UCP3 过表达在线粒体、心脏功能和细胞存活方面诱导的心脏保护作用被 mPTP 开放剂 atractyloside 所阻断，并用 PI3K/Akt 抑制剂wortmannin 部分抑制。此外，H₂O₂PC 上调了 Akt 的磷酸化，糖原合酶激酶 3β的磷酸化被 UCP3 的敲低所阻断，但被 UCP3 的过表达所模拟。
UCP3 通过与 ANT 的相互作用和 PI3K/Akt 途径抑制 mPTP 开放来维持线粒体功能，从而介导 H₂O₂PC 对 I/R 损伤的心脏保护作用。我们的研究结果揭示了 UCP3 在心脏保护中的新机制。
