Mechanisms of Calcium Transients in Neuronal Development

描述（由申请人提供）：在之前的工作中，我们发现了胚胎非洲爪蟾脊髓神经元细胞内钙（Ca）的3类自发瞬时升高，并表明它们具有不同的功能，在突触形成之前以频率依赖的方式调节分化方面：1)钙峰是由发育瞬时钙依赖动作电位产生的，并调节神经递质的表达。2)生长锥Ca瞬态在生长锥局部产生，调节轴突延伸速率。3)丝状锥体在丝状锥体顶端产生Ca瞬变，调节生长锥体的转动。本研究有3个具体目的，旨在解决Ca瞬态在这些胚胎脊髓神经元分化中的作用机制。第一个目的是研究钙峰调节神经递质表达的机制。第二个目的是分析导致钙峰的开始和终止的膜电位变化的机制。第三个目的是研究电压门控钙通道的调制如何调节生长锥的功能。我们描述实验来解决以下问题：哪些分子参与Ca的作用

DESCRIPTION (provided by applicant): In previous work we discovered 3 classes of spontaneous transient elevations of intracellular calcium (Ca) in embryonic Xenopus spinal neurons and showed that they have distinct functions, regulating aspects of differentiation in a frequency-dependent manner prior to synapse formation: 1) Ca spikes are generated by developmentally transient Ca-dependent action potentials and regulate expression of neurotransmitters. 2) Growth cone Ca transients are generated locally in the growth cone and regulate the rate of axon extension. 3) Filopodial Ca transients are produced at the tips of filopodia and regulate growth cone turning. The proposed research has 3 specific aims that address the mechanisms of action of Ca transients in differentiation of these embryonic spinal neurons. The first aim investigates the mechanisms by which Ca spikes regulate neurotransmitter expression. The second aim analyzes the mechanism generating changes in membrane potential that lead to onset and termination of Ca spiking. The third aim investigates how modulation of voltage-gated Ca channels regulates growth cone function. We describe experiments to address the following questions: What molecules are involved in the action of Ca spikes? What mechanisms generate the changes in membrane potential that lead to onset and termination of the period of Ca spiking? Does modulation of voltage-gated Ca channels by mechanical forces or Trk receptors regulate growth cone function? The immediate goal of this research is to test hypotheses about the mechanisms of Ca transients in the early stages of differentiation of vertebrate spinal neurons. The long term goal is to provide information about the cellular and molecular machinery that governs processes of development, which will contribute to understanding developmental disorders of the nervous system.