Williamson Courtney L, Dabkowski Erinne R, Dillmann Wolfgang H, Hollander John M
West Virginia University School of Medicine, Division of Exercise Physiology, Center for Interdisciplinary Research in Cardiovascular Sciences, 1 Medical Center Drive, Morgantown, WV 26506, USA.
Am J Physiol Heart Circ Physiol. 2008 Jan;294(1):H249-56. doi: 10.1152/ajpheart.00775.2007. Epub 2007 Nov 2.
The majority of mitochondrial proteins are encoded by nuclear genes and synthesized in the cytosol as preproteins containing a mitochondria import sequence. Preproteins traverse the outer mitochondrial membrane in an unfolded state and then translocate through the inner membrane into the matrix via import machinery that includes mitochondrial heat shock protein 70 (mtHSP70). Neonatal rat cardiac myocytes (NCM) infected with an adenoviral vector expressing mtHSP70 or an empty control (Adv(-)) for 48 h were submitted to 8 h of simulated ischemia (hypoxia) followed by 16 h of reperfusion (reoxygenation). Infection with mtHSP70 virus yielded an increase in mtHSP70 protein in NCM mitochondria compared with Adv(-) (P < 0.05). Cell viability after simulated ischemia/reperfusion (I/R) was decreased in both Adv(-) and mtHSP70 groups, relative to control (P < 0.05), but mtHSP70-infected NCM had enhanced viability after I/R relative to Adv-infected NCM (P < 0.05). Simulated I/R caused an increase in reactive oxygen species generation and lipid peroxidation in Adv-infected NCM (P < 0.05, for both) that was not observed in mtHSP70-infected NCM. Mitochondrial complex III and IV activities were greater in mtHSP70-infected NCM after simulated I/R compared with Adv(-) (P < 0.05 for both). After simulated I/R, ATP content increased in mtHSP70-infected NCM, compared with Adv(-) (P < 0.05). Apoptotic markers were decreased in mtHSP70-infected NCM compared with Adv(-) after simulated I/R (P < 0.05). These results indicate that overexpression of mtHSP70 protects the mitochondria against damage from simulated I/R that may be due to a decrease in reactive oxygen species leading to preservation of mitochondrial complex function activities and ATP formation.
大多数线粒体蛋白由核基因编码，并在胞质溶胶中作为含有线粒体导入序列的前体蛋白合成。前体蛋白以未折叠状态穿过线粒体外膜，然后通过包括线粒体热休克蛋白70（mtHSP70）的导入机制穿过内膜进入基质。用表达mtHSP70的腺病毒载体或空载体对照（Adv(-)）感染新生大鼠心肌细胞（NCM）48小时，然后进行8小时的模拟缺血（缺氧），随后再灌注16小时（复氧）。与Adv(-)相比，用mtHSP70病毒感染使NCM线粒体中的mtHSP70蛋白增加（P<0.05）。相对于对照，模拟缺血/再灌注（I/R）后Adv(-)组和mtHSP70组的细胞活力均降低（P<0.05），但与Adv感染的NCM相比，mtHSP70感染的NCM在I/R后活力增强（P<0.05）。模拟I/R导致Adv感染的NCM中活性氧生成和脂质过氧化增加（两者均P<0.05），而在mtHSP70感染的NCM中未观察到。模拟I/R后，与Adv(-)相比，mtHSP70感染的NCM中线粒体复合物III和IV的活性更高（两者均P<0.05）。模拟I/R后，与Adv(-)相比，mtHSP70感染的NCM中ATP含量增加（P<0.05）。模拟I/R后，与Adv(-)相比，mtHSP70感染的NCM中凋亡标志物减少（P<0.05）。这些结果表明，mtHSP70的过表达可保护线粒体免受模拟I/R的损伤，这可能是由于活性氧的减少导致线粒体复合物功能活性和ATP形成的保留。
