Cell Cycle Regulation of Neuronal Apoptosis

描述（由申请人提供）：拟议研究的长期目标是阐明发育中的哺乳动物大脑中神经元凋亡的调节机制。越来越多的证据表明，细胞周期的组成部分在大脑中垂死的神经元中被重新激活。然而，细胞周期机制控制神经元凋亡的作用和机制在很大程度上仍有待阐明。我们发现有丝分裂激酶Cdc2可诱导原代大鼠小脑颗粒神经元凋亡。这些发现提出了两个主要问题：Cdc2如何触发有丝分裂后神经元的凋亡，以及Cdc2功能在完整发育的小脑皮层中神经元凋亡中的作用？为了解决这些问题，我们提出以下具体目标：(1)阐明Cdc2诱导神经元凋亡的机制。我们的初步研究表明，Cdc2通过磷酸化主要促存活激酶Akt的蛋白底物来触发细胞凋亡，并产生抑制Akt促进神经元存活的净效应。我们将采取多管齐下的方法来鉴定有助于神经元凋亡的Cdc2的新底物。(2)测定Cdc2在完整小脑皮层中的功能。我们将在大鼠小脑切片和活体实验中对大鼠小脑皮层颗粒神经元中Cdc2的表达和活性进行表征，并确定抑制Cdc2对小脑皮层神经元凋亡的影响。总之，本研究将为有丝分裂后神经元凋亡中细胞周期再激活的作用和机制提供基础和新颖的见解。由于细胞周期再激活被认为在神经退行性疾病中起着重要作用，我们的研究也应该导致对这些破坏性脑疾病发病机制的新见解。

DESCRIPTION (provided by applicant): The long-term goals of the proposed research are to elucidate the mechanisms that regulate apoptosis of neurons in the developing mammalian brain. Growing evidence suggests that components of the cell cycle are reactivated in dying neurons in the brain. However, the role and mechanisms by which the cell cycle machinery control apoptosis of neurons remain largely to be elucidated. We have found that the mitotic kinase Cdc2 induces apoptosis in primary rat cerebellar granule neurons. These findings raise two major questions: how does Cdc2 trigger apoptosis of postmitotic neurons, and what is the role of Cdc2 function in neuronal apoptosis in the intact developing cerebellar cortex? To address these questions we propose the following specific aims: (1) Elucidate the mechanisms by which Cdc2 induces neuronal apoptosis. Our preliminary studies suggest the hypothesis that Cdc2 triggers apoptosis by phosphorylating protein substrates of the major pro-survival kinase Akt with the net effect of opposing Akt-promotion of neuronal survival. We will take a multi-pronged approach to identify novel substrates of Cdc2 that contribute to neuronal apoptosis. (2) Determine Cdc2 function in the intact cerebellar cortex. We will characterize the expression and activity of Cdc2 in granule neurons in the rat cerebellar cortex in both rat cerebellar slices and in vivo, and we will determine the effect of inhibition of Cdc2 on neuronal apoptosis in the cerebellar cortex. Together, the proposed research should provide fundamental and novel insights into the role and mechanisms of cell cycle reactivation in apoptosis of postmitotic neurons. Since cell cycle reactivation is thought to play an important role in neurodegenerative diseases, our studies should also lead to novel insights into the pathogenesis of these devastating diseases of brain.