Actions of BDNF on Ca2+ Signals in Hippocampal Neurons

脑源性神经营养因子已成为依赖活性的突触发育和可塑性的有效调节剂。ITS中的功能障碍 贩运和释放，以及通过其受体TrkB发出的信号，都与许多 发育性和神经退行性脑疾病。流行的观点是，从对IP敏感的存储中释放出钙离子 是脑源性神经营养因子调节钙稳态的唯一机制。然而，识别特定目标的直接证据 信号和介导这些作用的钙离子来源是有限的，也是相互矛盾的。此外，我们什么都不知道。 关于神经元活动过程中释放的天然BDNF的作用，尽管有广泛的证据表明 外源性应用脑源性神经营养因子。该项目的长期目标是确定TrkB激活的机制 启动脑源性神经营养因子对海马神经元和突触的广泛影响。在这场竞争性更新中，我们将 集中在我们的观察中，BDNF引起与膜电流相关的缓慢而持续的钙信号， 这使人联想到TRPC通道介导的电容性钙离子内流和非选择性阳离子电流。这个 具体的假说是，BDNF触发依赖TrkB的PLCy激活，然后从IP- CA1锥体神经元中的敏感储藏，导致电容性CO2*进入的激活和持续的内向 电流由TRPC通道介导。前两个目标将确定外源应用的基本动作 BDNF对膜电流和细胞内钙水平的影响，而第三个目标将利用这一知识来识别类似的 由天然脑源性神经营养因子引起的反应在传入刺激过程中释放。同时进行钙离子成像和 电生理记录，结合药物抑制剂、功能阻断抗体和siRNA- 介导的基因敲除将被用来识别信号通路的组成部分。BDNF清道夫将允许 确定传入活动释放的BDNF是否会引起类似的钙信号和内向电流。我们期待着 建议的研究，以提供迄今为止最全面的BDNF对膜的即时作用 电流和细胞内钙稳态，导致突触功能、结构和可塑性的持久变化。

BDNF has emerged as a potent modulator of activity-dependent synaptic development and plasticity. Dysfunctions in its trafficking and release, as well as in signaling through its receptor TrkB, have been implicated in the etiology of numerous developmental and neurodegenerative brain disorders. The prevailing notion is that Ca2+ release from IPs-sensitive stores is the only mechanism for BDNF to modulate Ca2+ homeostasis. However, direct evidence identifying the specific signaling and the sources of Ca2+ ions mediating those actions is limited and contradictory. In addition, nothing is known about the actions of native BDNF released during neuronal activity, despite the extensive evidence of the effects of exogenously applied BDNF. The long-term goal of this project is to identify the mechanisms by which TrkB activation sets in motion the wide range of BDNF effects on hippocampal neurons and synapses. In this competing renewal we will focus on our observation that BDNF elicits slow and sustained Ca2+ signals associated with membrane currents, reminiscent of capacitative Ca2+ entry and non-selective cationic currents mediated by TRPC channels, respectively. The specific hypothesis is that BDNF triggers TrkB-dependent PLCy activation followed by Ca2+ mobilization from IP- sensitive stores in CA1 pyramidal neurons, leading to the activation of capacitative Co2* entry and a sustained inward current mediated by TRPC channels. The first two Aims will identify the elementary actions of exogenously applied BDNF on membrane currents and intracellular Ca2+ levels, while the third Aim will use this knowledge to identify similar responses evoked by native BDNF released during afferent stimulation. Simultaneous Ca2+ imaging and electrophysiological recording, combined with pharmacological inhibitors, function-blocking antibodies, and siRNA- mediated knockdown will be used to identify the components of the signaling pathway. BDNF scavengers will allow determining whether BDNF released by afferent activity evokes similar Ca2+ signals and inward currents. We expect the proposed studies to provide the most comprehensiveunderstatingto date of the immediateactions of BDNF on membrane currents and intracellular Ca2+ homeostasis, leading to enduring changes in synaptic function, structure, and plasticity.