KINASE-MEDIATED SIGNALING PATHWAYS IN NEURONAL APOPTOSIS

描述(摘自申请者的摘要)：我们正在研究 激酶介导的信号通路促进神经元存活并防止 颗粒神经元原代培养中的细胞凋亡。相关的神经营养因子有 胰岛素样生长因子与脑源性神经营养因子 (BDNF)。谷氨酸是调节神经元的主要神经递质。 通过与不同的谷氨酸受体通道相互作用而发挥活性， 在此称为N-甲基-D-天冬氨酸(NMDA)和非NMDA受体。 这些药物与神经元血浆中各自受体的结合 膜启动细胞内信号级联的激活，调节 促凋亡或抗凋亡基因的转录。两者之间的平衡 这些基因产物最终决定了细胞的命运。早期颗粒细胞 发育，在神经元形成突触连接之前，它们依赖于 专门针对神经营养因子，存在于沐浴它们的血清中，用于 生死存亡。我们有新的证据表明该家族的特定亚型 磷脂敏感蛋白激酶(PKCs)，称为非典型PKCs (APKCs)，是神经营养素依赖生存的关键组成部分 路径。我们对这些数据相当热情，因为几乎没有什么是 目前已知的APKCs的神经功能。此外，初步的 数据表明，抑制aPKCs会减少丝氨酸-133的磷酸化。 核转录因子CREB。此应用程序的一个目标是 扩展我们的研究，检查神经营养素依赖之间的联系 激活APKCs。CREB的磷酸化。和生存。在许多神经元中 兴奋性神经递质电刺激不足的人群 或者营养因子不足使细胞更有可能死亡。“钙调整点” 假说“假设”认为胞浆中大量的钙活动决定了 未成熟神经元需要营养因子抑制的程度 导致细胞凋亡的机制(Koike等人，1989)。因此，许多 在分离培养中生长的神经元类型可以从死亡中拯救出来， 由剥夺神经营养素诱导，通过在介质中包含 使钙离子持续升高。这些代理包括提升的KCI代理 通过电压敏感的钙通道(VSCCs)和直接作用于 NMDA受体通道(NRs)。我们有新的证据表明钙离子和 钙调蛋白依赖的激酶，命名为CaM KIV，其底物CREB是 这条钙依赖的信号通路的关键组成部分。 免疫细胞化学证据还表明，这些治疗可以诱导 CaM KIV从胞核到胞浆的再分布。第二个目标是 这个应用程序是为了扩展我们的研究，检查 钙、CaM KIV对CREB的磷酸化，与存活率有关。磷酸化和 CREB的激活可能介导了抗凋亡基因的诱导，如 Bc1-2，或抑制促凋亡基因，如bax。这是第三个目标 应用是比较bc1-2和bax rnRNAs在 促进存活或凋亡的培养条件。

DESCRIPTION (From the applicant's abstract): We are studying the kinase-mediated signaling pathways that promote neuronal survival and prevent apoptosis in primary cultures of granule neurons. Relevant neurotrophins are insulin-like growth factor (IGF-1) and brain-derived neurotrophic factor (BDNF). Glutamate is the predominant neurotransmitter that regulates neuronal activity through its interaction with different glutamate receptor-channels, referred to herein as N-methyl-D-aspartate (NMDA) and non-NMDA receptors. Binding of these agents to their respective receptors in the neuronal plasma membrane initiates activation of intracellular signaling cascades that regulate the transcription of pro-apoptotic or anti-apoptotic genes. The balance between these gene products ultimately determines cell fate. Early in granule cell development, before neurons have formed synaptic connections, they rely exclusively on neurotrophic factors, present in the serum that bathes them, for survival. We have novel evidence that particular isoforms of the family of phospholipid-sensitive protein kinases (PKCs), designated as atypical PKCs (aPKCs), are critical components of the neurotrophin-dependent survival pathway. We are quite enthusiastic about these data since almost nothing is currently known about the neuronal functions of aPKCs. Moreover, preliminary data indicate that inhibition of aPKCs reduces phosphorylation on serine-133 of the nuclear transcription factor CREB. One goal of this application is to extend our studies examining the linkage between neurotrophin-dependent activation of aPKCs. phosphorvlation of CREB. and survival. In many neuronal populations, inadequate electrical stimulation by excitatory neurotransmitters or inadequate trophic factor make cell death more likely. A "Ca2+ set-point hypothesis" postulates that the bulk cytosolic Ca2+ activity determines the degree to which immature neurons require trophic factor to suppress the mechanism responsible for apoptosis (Koike et al., 1989). Accordingly, many types of neurons grown in dissociated culture can be rescued from death, induced by neurotrophin deprivation, by inclusion of agents in the media that produce a sustained elevation in Ca2+. These agents include elevated KCI acting through voltage-sensitive Ca2+ channels (VSCCs) and NMDA acting directly upon NMDA receptor channels (NRs). We have novel evidence that a Ca2+ and calmodulin-dependent kinase, designated as CaM KIV, and its substrate CREB are critical components of this Ca2+-dependent signaling pathway. Immunocytochemical evidence also indicated that these treatments induce the redistribution of CaM KIV from the nucleus to the cytosol. A second goal of this application is to extend our studies examining the linkage between calcium, CaM KIV phosphorvlation of CREB, and survival. Phosphorylation and activation of CREB may mediate induction of anti-apoptotic genes, such as bc1-2, or repression of pro-apoptotic genes, such as bax. A third goal in this application is to compare the expression levels of bc1-2 and bax rnRNAs under culture conditions promoting survival or apoptosis.