Preconditioning brain white matter against ischemia

项目总结 老龄化人口的增长，加上中风护理的改善，导致幸存者和 反复发生的缺血性事件的增加，给负担过重的医疗保健经济带来了重大挑战 这些病人。因此，诱导大脑对缺血耐受的方法获得了新的进展。 临床和实验研究的动力。然而，缺血预适应(IPC)的机制有 主要研究灰质(GM)，尽管白质(WM)损伤和轴突功能障碍是关键 中风患者临床缺陷的构成因素。此外，大多数IPC的体内模型都是在 啮齿动物由短暂的缺氧/缺血组成，不适用于临床环境，因为 治疗学。因此，有一个尚未得到满足的需要，即建立临床适用的药理学方法来治疗 使大脑对缺血进行预调节。我们的初步结果显示，FDA的CX-4945(Silmitasertib)- 批准的酪蛋白激酶2(CK2)抑制剂，作为WM的先决条件，促进轴突功能恢复和改善 体外或体内缺血损伤后的行为结果。虽然衰老减少了神经元的IPC，但CX-4945 与之相比，年轻的和老年的WM通过保持线粒体的运动性而预适应。因为门槛是 据报道，前提条件在女性中更高，目前这项提议的主要目标是了解 抑制CK2在青年和老年男女西医中的预适应机制。 我们已报道CK2通过CDK5和AKT信号通路介导缺血性WM损伤。因此，CK2 抑制与保存少突胶质细胞、轴突结构和功能以及保护 年轻和老年WM的线粒体动力学。我们的初步数据显示，短暂的CK2抑制期 CX-4945通过维持线粒体的运动性，有效地预先调节轴突功能。此外， CX-4945预适应显著减轻在体局灶性脑损伤后观察到的行为缺陷 皮质下WM损伤。我们确认miR-501是一种被CK2抑制的缺血上调的miRNA MiR-501和MIRO-2对轴突线粒体的抑制和相互作用 能动性。中风患者血浆样本中miR-501水平与年龄和性别相比也有类似的上调。 配对对照建议将CK2作为临床相关的治疗靶点。因此，我们建议延长这些规定 通过验证我们的新假设，即CK2抑制通过差异调节CDK5而预先形成WM的研究 和AKT信号通路通过相互调节miR-501和Miro-2来维持线粒体的动力学 级别。我们将结合电生理学、高级成像、线粒体功能分析、小鼠miRNA 表达和调控研究，人miRNA在血浆和人脑中的表达研究，以及验证 以确定CK2抑制是否通过CDK5或AKT发挥调节作用 线粒体蛋白通过改变miRNA图谱来预适应WM抗缺血。

PROJECT SUMMARY A growth in the aging population together with improved stroke care has resulted in an increase in survivors and a rise in recurrent ischemic events, presenting major challenges for overburdened healthcare economics for these patients. Consequently, approaches to induce tolerance in the brain against ischemia have gained new momentum in clinical and experimental studies. However, mechanisms of ischemic preconditioning (IPC) have been primarily studied in gray matter (GM), despite white matter (WM) injury and axon dysfunction being critical components of clinical deficits observed in stroke patients. Moreover, most in vivo models of IPC performed in rodents consist of short episodes of hypoxia/ischemia and are not applicable to translate into clinical settings as therapeutics. Therefore, there is an unmet need to establish clinically applicable pharmacological approaches to preconditioning the brain against ischemia. Our preliminary results show that CX-4945 (Silmitasertib), an FDA- approved Casein Kinase 2 (CK2) inhibitor, preconditions WM, promotes axon function recovery and improves behavioral outcomes after an in vitro or in vivo ischemic injury. Although aging reduces neuronal IPC, CX-4945 comparably preconditions young and aging WM by preserving mitochondrial motility. Because the threshold to precondition is reported to be higher in females, the main goal of this current proposal is to understand the mechanisms of preconditioning conferred by CK2 inhibition in young and aging male and female WM. We have reported that CK2 signals via the CDK5 and AKT pathways to mediate ischemic WM injury. Thus, CK2 inhibition correlates with the preservation of oligodendrocytes, axon structure and function, and conservation of mitochondrial dynamics in young and aging WM. Our preliminary data show that a brief period of CK2 inhibition with CX-4945 effectively preconditions axon function by maintaining mitochondrial motility. Furthermore, preconditioning with CX-4945 considerably attenuates behavioral deficits observed after an in vivo focal subcortical WM injury. We identified miR-501 as an ischemia-upregulated miRNA that is suppressed by CK2 inhibition, and reciprocal interaction between levels of miR-501 and Miro-2 regulates axonal mitochondrial motility. A similar upregulation of miR-501 levels in stroke patient plasma samples compared to age- and sex- matched controls propose CK2 as a clinically relevant therapeutic target. Therefore, we propose to extend these studies by testing our novel hypothesis that CK2 inhibition preconditions WM by differentially regulating the CDK5 and AKT signaling pathways to maintain mitochondrial dynamics by reciprocally regulating miR-501 and Miro-2 levels. We will combine electrophysiology, advanced imaging, functional analysis of mitochondria, mouse miRNA expression and regulation studies, human miRNA expression in plasma and human brain studies, and validation of regulated signaling molecules to determine whether CK2 inhibition acts via CDK5 or AKT to regulate mitochondrial proteins through alteration of miRNA profiles to precondition WM against ischemia.