Mitochondrial Ion Channels in Hypoxic Neurons

啮齿动物短暂性全脑缺血(小鼠2条血管闭塞，2VO)诱导海马区延迟性死亡 CA1神经元，是人类缺血性脑损伤和持久的海马区记忆缺陷的模型。 神经元死亡前发生的事件包括caspase和促凋亡的bcl2家族成员(Bax) 抗死亡蛋白Bcl2家族蛋白Bclxl的激活、裂解、细胞内钙调节失调和大 电导性线粒体通道活性。大电导的开放，依赖于钙离子，内部 线粒体膜通道发生在损伤早期，因此识别和靶向 长期以来，这一内膜通道的研究一直是基础研究和临床研究的重要目标。 内膜通道称为线粒体通透性转换孔(MPTP)。它已被激活 神经细胞钙调节失调和线粒体肽-脯氨酰顺-反式异构酶结合 亲环素D(CypD)。据报道，CypD结合在OSCP的ATP合成酶的定子区域 亚单位。CypD结合被众所周知的MPTP抑制剂环孢素A(CsA)抑制，CsA可以减弱MPT 通道激活。在之前的资助期间，我们第一个证明了ATP合成酶 膜包埋的c-亚基形成了mptp的最大已知通道，即ATP合成酶c-亚基泄漏。 通道(ACLC)，我们发现CsA通过与ATP合成酶F1/STATOR结合来抑制ACLC的活性 部分，因为当ATP合成酶的膜部分被化学处理时，通道抑制不会发生 已剥离F1/定子组件。我们还报道了地塞米松(Dex)是一种安全的ATP调节剂。 直接与定子复合体上的OSCP/亚单位b结合的合成酶泄漏。地塞米松在一种 神经发育性大脑障碍。在目前的更新中，我们将重点关注ACLC作为抑制的目标 MPTP开场和死亡。通过突变c-亚基来降低通道活性，我们将抑制ACLC的开放 并在神经元和体内防止谷氨酸兴奋性毒性过程中的线粒体通透性转变(MPT) 小鼠缺血性脑损伤模型。我们将确定记忆丧失，一种严重的、长期的暂时性全球影响 啮齿动物和人类的缺血，将通过这种遗传策略来预防。

Transient global ischemia in rodents (2 vessel occlusion in mice, 2VO) induces delayed death of hippocampal CA1 neurons and is a model for human ischemic brain injury and long lasting hippocampal memory deficits. Events that occur before neuronal death include caspase and pro-apoptotic Bcl-2 family member (Bax) activation, cleavage of the anti-death Bcl-2 family protein Bcl-xL, cellular Ca2+ dysregulation and large conductance mitochondrial channel activity. The opening of a large conductance, Ca2+ dependent, inner mitochondrial membrane channel occurs early during the injury phase, therefore the identification and targeting of this inner membrane channel has long been an important goal of both basic research and clinical communities. The inner membrane channel is known as the mitochondrial permeability transition pore (mPTP). It is activated by neuronal Ca2+ dysregulation and by the binding of the mitochondrial peptidyl-prolyl cis-trans isomerase cyclophilin D (CypD). It has been reported that CypD binds to the stator region of the ATP synthase at the OSCP subunit. CypD binding is inhibited by the well-known mPTP inhibitor cyclosporine A (CsA), which attenuates mPT channel activation. During the previous funding period, we were the first to demonstrate that the ATP synthase membrane-embedded c-subunit forms the largest known channel of the mPTP, the ATP synthase c-subunit leak channel (ACLC), and we showed that CsA inhibits ACLC activity by binding within the ATP synthase F1/stator portion because channel inhibition fails to occur when the membrane portions of the ATP synthase are chemically stripped of the F1/stator components. We also reported that Dexpramipexole (Dex) is a safe modulator of ATP synthase leak that binds directly to OSCP/subunit b on the stator complex. Dex ameliorates disease in a neurodevelopmental brain disorder. In this current renewal we will focus on the ACLC as the target to inhibit mPTP opening and death. By mutation of the c-subunit to reduce channel activity, we will inhibit ACLC opening and prevent mitochondrial permeability transition (mPT) during glutamate excitotoxicity in neurons and in vivo ischemic brain injury in mice. We will determine if memory loss, a severe, long lasting effect of transient global ischemia in rodents and humans, will be prevented by this genetic strategy.