Cerebral Vascular Disease Research Laboratories, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
Sci Rep. 2016 Jul 20;6:29790. doi: 10.1038/srep29790.
Sirtuin 5 (SIRT5) is a mitochondrial-localized NAD(+)-dependent lysine desuccinylase and a major regulator of the mitochondrial succinylome. We wanted to determine whether SIRT5 is activated by protein kinase C epsilon (PKCε)-mediated increases in mitochondrial Nampt and whether SIRT5 regulates mitochondrial bioenergetics and neuroprotection against cerebral ischemia. In isolated mitochondria from rat cortical cultures, PKCε activation increased SIRT5 levels and desuccinylation activity in a Nampt-dependent manner. PKCε activation did not lead to significant modifications in SIRT3 activity, the major mitochondrial lysine deacetylase. Assessments of mitochondrial bioenergetics in the cortex of wild type (WT) and SIRT5-/- mice revealed that SIRT5 regulates oxygen consumption in the presence of complex I, complex II, and complex IV substrates. To explore the potential role of SIRT5 in PKCε-mediated protection, we compared WT and SIRT5-/- mice by employing both in vitro and in vivo ischemia paradigms. PKCε-mediated decreases in cell death following oxygen-glucose deprivation were abolished in cortical cultures harvested from SIRT5-/- mice. Furthermore, PKCε failed to prevent cortical degeneration following MCAO in SIRT5-/- mice. Collectively this demonstrates that SIRT5 is an important mitochondrial enzyme for protection against metabolic and ischemic stress following PKCε activation in the brain.
Sirtuin 5（SIRT5）是一种定位于线粒体的 NAD（+）依赖性赖氨酸去琥珀酰基酶，也是线粒体琥珀酰基组的主要调节因子。我们想确定 SIRT5 是否被蛋白激酶 C ɛ（PKCε）介导的线粒体 Nampt 的增加所激活，以及 SIRT5 是否调节线粒体生物能学和对脑缺血的神经保护作用。在来自大鼠皮质培养物的分离线粒体中，PKCε 的激活以 Nampt 依赖性的方式增加了 SIRT5 的水平和去琥珀酰基化活性。PKCε 的激活并没有导致主要的线粒体赖氨酸去乙酰化酶 SIRT3 活性的显著改变。在 WT 和 SIRT5-/- 小鼠的皮质中评估线粒体生物能学表明，SIRT5 调节在存在复合物 I、复合物 II 和复合物 IV 底物时的耗氧量。为了探索 SIRT5 在 PKCε 介导的保护中的潜在作用，我们通过体外和体内缺血模型比较了 WT 和 SIRT5-/- 小鼠。从 SIRT5-/- 小鼠中分离的皮质培养物中，PKCε 介导的氧葡萄糖剥夺后细胞死亡的减少被消除。此外，PKCε 未能防止 SIRT5-/- 小鼠 MCAO 后的皮质退化。总的来说，这表明 SIRT5 是一种重要的线粒体酶，可在大脑中 PKCε 激活后抵抗代谢和缺血应激。
