Bioenergetic Failure Underlies Cerebral Dysmaturity After Perinatal Brain Injury

项目摘要 长期认知障碍和学习障碍是一个主要的公共卫生问题， 超过一半的早产儿有不成熟的肺损伤。这类婴儿的大脑发育全面延迟， 灰色和白色物质结构的成熟，可能是由于对缺氧诱导的氧化 在这个关键时期的压力。这种压力可导致线粒体功能障碍。如果是依赖性的 氧化代谢是未成熟祖细胞成熟所必需的，那么线粒体功能障碍可以 导致祖细胞不能及时成熟。关于代谢改变或 神经前体细胞成熟对发育中大脑线粒体代谢的依赖性。我们 工作将填补这一知识空白。我们使用慢性缺氧的啮齿动物模型来重现未成熟的肺 一种常见于极早产儿的损伤，可导致整体灰质和白色物质细胞发育不良 以及相关的超微结构和行为缺陷。在这项研究中，我们将研究代谢的影响， 缺氧对海马发育不良的影响，并确定线粒体破坏的发育结果。 我们对海马体的初步数据表明：i）缺氧导致生物化学的长期下降， 线粒体功能标志物; ii）缺氧损害丙酮酸脱氢酶E1α非依赖性表达 其抑制剂;和iii）从表达GFAP的放射状神经胶质细胞中有条件地去除丙酮酸脱氢酶E1α 干细胞阻止它们成熟。促进围产期脑损伤后恢复的一个潜在靶点是 及时恢复线粒体功能和氧化代谢。我们公布的和初步的数据 强烈提示鼻内肝素结合表皮生长因子[HB-EGF]治疗 缺氧后可逆转缺氧诱导的细胞发育不良， 天冬氨酸，并通过靶向线粒体改善神经行为缺陷。我们假设 线粒体功能障碍导致海马神经前体细胞发育延迟， 进行氧化能量代谢，从而阻止它们的成熟。我们将检验这个假设， 恢复线粒体功能将使这些细胞能够满足其生物能量需求， 海马体中的细胞成熟和功能恢复。这些假设将在三个测试 具体目标。在目标1中，我们将确定缺氧是否损害海马线粒体功能。 在目标2中，我们将确定是否缺氧或细胞特异性去除丙酮酸脱氢酶E1α， 海马神经祖细胞延迟分化和海马行为缺陷。在目标3中， 将确定缺氧后鼻内HB-EGF治疗是否增强线粒体功能。 成功完成这些目标将阐明一个基本的生化机制， 缺氧诱导损伤后神经前体细胞的分化失败，并定义了一种新的代谢 HB-EGF促进新生儿脑损伤后细胞和功能恢复的机制。

PROJECT SUMMARY ABSTRACT Long-term cognitive impairment and learning disabilities are a major public health concern that affects more than half of infants born very preterm with immature lung injury. Such infants have a global delay in cerebral maturation of gray and white matter structures, likely caused by high susceptibility to hypoxia-induced oxidative stress during this critical period. This stress can result in mitochondrial dysfunction. If mitochondrial-dependent oxidative metabolism is required for immature progenitor cells to mature, then mitochondrial dysfunction can result in failure of timely progenitor cell maturation. Little is known about the metabolic alterations or the dependence of neural progenitor cell maturation on mitochondrial metabolism in the developing brain. Our work will fill this gap in knowledge. We use a rodent model of chronic hypoxia to recapitulate the immature lung injury commonly found in very preterm infants, which causes global gray and white matter cellular dysmaturity and associated ultrastructural and behavioral deficits. In this study, we will investigate the metabolic effects of hypoxia on hippocampal dysmaturation and determine the developmental outcome of mitochondrial disruption. Our preliminary data on the hippocampus indicate that: i) hypoxia causes long-term decreases in biochemical markers of mitochondrial function; ii) hypoxia impairs expression of pyruvate dehydrogenase E1α independent of its inhibitors; and iii) conditional removal of pyruvate dehydrogenase E1α from GFAP-expressing radial glia stem cells prevents their maturation. A potential target for promoting recovery after perinatal brain injury is timely restoration of mitochondrial function and oxidative metabolism. Our published and preliminary data strongly suggest the novel findings that intranasal heparin-binding epidermal growth factor [HB-EGF] treatment after hypoxia may reverse hypoxia-induced cellular dysmaturation, restore mitochondrially produced N-acetyl aspartate, and ameliorate neurobehavioral deficits by targeting the mitochondria. We hypothesize that mitochondrial dysfunction results in delayed development of hippocampal neural progenitor cell capacity to perform oxidative energy metabolism, thus preventing their maturation. We will test the hypothesis that restoring mitochondrial function will enable these cells to meet their bioenergetic demands, permitting timely cellular maturation and recovery of function in the hippocampus. These hypotheses will be tested in three specific aims. In Aim 1, we will determine whether hypoxia impairs mitochondrial function in the hippocampus. In Aim 2, we will determine whether hypoxia or cell-specific removal of pyruvate dehydrogenase E1α in hippocampal neural progenitor cells delays differentiation and hippocampal behavioral deficits. In Aim 3, we will determine whether intranasal HB-EGF treatment after hypoxia enhances mitochondrial function. Successful completion of these aims will elucidate a fundamental biochemical mechanism that determines differentiation failure of neural progenitor cells after hypoxia-induced injury and define a novel metabolic mechanism by which HB-EGF facilitates cellular and functional recovery after neonatal brain injury.