Glutamate Receptors in Hypoxic-ischemic Injury to Developing Oligodendrocytes

描述（由申请人提供）：发育中大脑的缺氧缺血性损伤导致破坏性神经后果。值得注意的是，缺氧缺血性脑损伤的模式是高度年龄依赖性的。在足月儿中，缺氧缺血主要影响大脑皮层，伴有特征性神经元丢失。然而，在早产儿中，缺氧-缺血选择性地影响大脑白色物质，对发育中的少突胶质细胞（OL）有显著损伤，这种疾病称为脑室周围白质软化症（PVL）。发育中的OL（髓鞘形成前OL，称为“前OL”）非常容易受到缺氧缺血性损伤，并且是PVL的主要细胞底物。我们已经表明，谷氨酸受体（GluR）的表达在体内和体外发育调控的OL，离子型GluRs（iGluRs）介导的缺氧缺血性损伤前OL，但代谢型GluRs（mGluRs）可以调节这种损伤。然而，特定的iGluRs和mGluRs在缺氧缺血性前OL损伤中的作用及其信号传导机制仍不清楚。该提案的中心假设是Ca 2+渗透性iGluRs介导缺氧缺血性前OL损伤，并且第1组mGluRs可以调节这种损伤，从而导致iGluRs和mGluRs之间的分子相互作用以及不同受体后信号传导事件的整合。我们将集中在确定的前OL损伤的iGluRs和mGluRs之间的串扰的机制。本项目的目的是提供新的见解，缺氧缺血性前OL损伤的年龄特异性机制，并确定潜在的年龄特异性治疗策略，治疗脑白色物质障碍的基础前OL损伤。本提案的目的1是确定前OL兴奋性毒性中iGluR功能和信号传导的改变顺序，目的是鉴定特定的治疗可及靶点。目的2将扩展我们的初步结果，并进一步研究mGluRs在体内脑白色损伤中前OL损伤的新作用。目的3将确定iGluRs和mGluRs之间相互作用的分子机制。我们将研究mGluR调节是否导致iGluR亚基表达、磷酸化状态和内化的变化，并研究细胞内Ca 2+和氧化应激，以及信号分子如Akt（蛋白激酶B）、CaMKII（Ca 2 +/钙调蛋白激酶II）、CaN（钙调神经磷酸酶）和PKC（蛋白激酶C）在mGluR调节iGluR介导的前OL损伤中的特定作用。该项目的完成将有助于阐明缺氧缺血性前OL损伤的新机制，并确定新的治疗策略的发展目标，以控制脑白色物质障碍，如PVL，目前没有具体的治疗方法存在的前OL损伤。 公共卫生相关性：脑室周围白质软化症（PVL）是早产儿脑损伤的主要形式，也是脑性瘫痪的最常见原因。在美国出生的56，000名早产儿中，PVL影响了50%。S.然而，目前还没有治疗这种严重的人类疾病的方法。本项目旨在确定离子型和代谢型谷氨酸受体在发育中的少突胶质细胞（PVL的细胞基质）缺氧缺血损伤中的分子相互作用机制。通过该项目获得的科学知识可能有益于PVL预防策略的制定和脑瘫儿童的护理。

DESCRIPTION (provided by applicant): Hypoxic-ischemic injury to the developing brain leads to devastating neurological consequences. Strikingly, the pattern of hypoxic-ischemic brain injury is highly age-dependent. In term infants, hypoxia-ischemia predominantly affects cerebral cortex with characteristic neuronal loss. However, in premature infants, hypoxia- ischemia selectively affects cerebral white matter with prominent injury to the developing oligodendrocyte (OL), a disorder termed periventricular leukomalacia (PVL). The developing OL (pre-myelinating OL, termed "preOL") is highly vulnerable to hypoxic-ischemic injury and is the major cellular substrate of PVL. We have shown that glutamate receptor (GluR) expression is developmentally regulated on OLs in vivo and in vitro, and that ionotropic GluRs (iGluRs) mediate hypoxic-ischemic injury to preOLs, but metabotropic GluRs (mGluRs) can modulate this injury. However, the role of specific iGluRs and mGluRs in hypoxic-ischemic preOL injury and the signaling mechanisms remain largely unknown. The central hypothesis of the proposal is that Ca2+-permeable iGluRs mediate hypoxic-ischemic preOL injury and that group 1 mGluRs can modulate this injury, entailing the molecular interplay between iGluRs and mGluRs and the integration of distinct post-receptor signaling events. We will focus on determining the mechanisms of the crosstalk between iGluRs and mGluRs in preOL injury. The goal of this project is to provide new insights into the age-specific mechanisms of hypoxic-ischemic preOL injury, and to determine potential age-specific therapeutic strategies for treating preOL injury that underlies cerebral white matter disorders. Aim 1 of this proposal is to determine the sequence of alterations of iGluR function and signaling in preOL excitotoxicity, with the aim to identify specific therapeutically accessible targets. Aim 2 will expand upon our preliminary results and further investigate the novel role of mGluRs in preOL injury in developing cerebral white matter injury in vivo. Aim 3 will determine the molecular mechanisms of the interplay between iGluRs and mGluRs. We will examine whether mGluR modulation leads to changes in iGluR subunit expression, phosphorylation state, and internalization, and also investigate intracellular Ca2+ and oxidative stress, and the specific roles of signaling molecules such as Akt (protein kinase B), CaMKII (Ca2+/calmodulin kinase II), CaN (calcineurin), and PKC (protein kinase C) in the modulation of iGluR-mediated preOL injury by mGluRs. Completion of this project will help to elucidate novel mechanisms of hypoxic-ischemic preOL injury and to identify new targets for the development of therapeutic strategies to control preOL injury that underlies cerebral white matter disorders, such as PVL, for which no specific therapy currently exists. PUBLIC HEALTH RELEVANCE: Periventricular leukomalacia (PVL) is the predominant form of brain injury in the premature infant, and the most common cause of cerebral palsy. PVL affects up to 50% of the 56,000 premature infants born in the U. S. every year, yet currently no therapy exists for this serious human disorder. This project seeks to determine the mechanisms of the molecular interplay between ionotropic and metabotropic glutamate receptors in hypoxic- ischemic injury to the developing oligodendrocyte - the cellular substrate of PVL. The scientific knowledge to be acquired through this project is of likely benefit to the development of preventive strategies for PVL and the care of children with cerebral palsy.