Molecular Properties of Voltage-Sensitive Calcium Channels

电压敏感钙通道的分子特性

• 批准号: 8115018
• 负责人: WILLIAM A CATTERALL
• 金额: $ 33.44万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-09-09 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8115018
• 关键词: Affinity; Ataxia; Binding; Binding Sites; Biochemical; Brain; C-terminal; Calcium Channel; Calcium/calmodulin-dependent protein kinase; Calmodulin; Cells; Chemosensitization; Code; Complex; Docking; Epilepsy; Exocytosis; Failure; Family member; Fluorescence Resonance Energy Transfer; Glutamates; Health; Hormones; Lobe; Measures; Mental Depression; Mental disorders; Methods; Migraine; Molecular; Muscle; N-terminal; Nerve; Nervous system structure; Neuroglia; Neurons; P-Q type voltage-dependent calcium channel; Phosphorylation; Phosphotransferases; Positioning Attribute; Process; Property; Proteins; Reagent; Regulation; Relative (related person); Research; Role; SNAP receptor; Signal Transduction; Site; Specificity; Structure of superior cervical ganglion; Surveys; Synapses; Synaptic Transmission; Synaptic Vesicles; Synaptic plasticity; Testing; Tube; VSNL1 gene; base; calmodulin-dependent protein kinase II; insight; member; mutant; myristoylation; nervous system disorder; neurotransmitter release; novel; presynaptic; research study; response; sensor; synaptic function; transmission process; voltage; voltage clamp

DESCRIPTION (provided by applicant): P/Q-type Ca currents conducted by Cav2.1 channels are responsible for the Ca entry that initiates neurotransmitter release at most fast glutamatergic synapses. Ca entering through presynaptic Ca channels forms a local domain of high Ca concentration that activates exocytosis in the near vicinity. Therefore, synaptic vesicles must dock near presynaptic Ca channels to be efficiently released. Neurotransmitter release is dependent on the third or fourth power of the Ca current through the presynaptic Ca channels, so small changes in Ca entry have large effects on synaptic transmission. Ca-dependent facilitation and depression of synaptic transmission is an important determinant of information coding and transmission in the nervous system. Our results in the present project period have given important new insights into the function and regulation of presynaptic Ca channels in synaptic transmission and short-term synaptic plasticity. First, we have further defined the molecular mechanism for interaction of Ca channels with SNARE proteins and the regulation of that interaction by protein phosphorylation. Second, we have shown that the calmodulin-like neuronal Ca sensor (nCaS) protein VILIP-2 regulates Cav2.1 channels by interaction at the same binding site as calmodulin and CaBP1, but has a distinct set of regulatory effects. Third, we have found that N-terminal myristoylation is required for the distinct regulatory effects of CaBP1 and VILIP-2 on Cav2.1 channels and that the N-terminal lobe of these nCaS proteins confers their specificity of regulation. Fourth, we have discovered that nCaS-dependent facilitation and inactivation of Cav2.1 channels is primarily responsible for short-term facilitation and depression of synaptic transmission in transfected superior cervical ganglion (SCG) neuron synapses, providing the first insight into the molecular mechanisms responsible for short-term synaptic plasticity. Finally, we have found unexpectedly that Ca/calmodulin-dependent protein kinase II (CaMKII) regulates Cav2.1 channels by specific binding to a site on the C-terminal domain, potentially positioning the kinase for rapid response to Ca entry and phosphorylation of nearby proteins. In the next project period, we plan to build on these important advances to: 1. further define the molecular mechanisms of binding and regulation of Cav2.1 channels by nCaS proteins; 2. determine the functions of nCaS proteins in short-term synaptic plasticity; 3. explore the signaling functions of CaMKII specifically bound to Cav2.1 channels; and 4. determine the functional role of presynaptic CaMKII in synaptic transmission and synaptic plasticity. These experiments will provide novel insights into the regulation of presynaptic Ca channels and the role of this regulation in short-term synaptic plasticity, an essential form of information encoding and transmission in the nervous system. PUBLIC HEALTH RELEVANCE: Calcium channels in nerve terminals begin the process of synaptic transmission, which communicates information from one nerve to cell to another as well as to muscle and hormone-secreting cells. Failure of correct function and regulation of these calcium channels contributes to epilepsy, migraine, ataxia, and other neurological diseases. Our proposed research will provide novel insights into the regulation of these presynaptic calcium channels and their function in short-term synaptic plasticity, an essential process for normal coding and transmission of information in the nervous system and a target for neurological disease.

描述（由申请人提供）：由 Cav2.1 通道传导的 P/Q 型 Ca 电流负责在大多数快速谷氨酸能突触处启动神经递质释放的 Ca 进入。 Ca 通过突触前 Ca 通道进入，形成高 Ca 浓度的局部区域，激活附近的胞吐作用。因此，突触小泡必须停靠在突触前 Ca2+ 通道附近才能有效释放。神经递质的释放取决于通过突触前 Ca2+ 通道的 Ca2+ 电流的三次方或四次方，因此 Ca2+ 进入的微小变化会对突触传递产生很大影响。突触传递的 Ca 依赖性促进和抑制是神经系统信息编码和传递的重要决定因素。我们在当前项目期间的结果为突触前 Ca 离子通道在突触传递和短期突触可塑性中的功能和调节提供了重要的新见解。首先，我们进一步明确了 Ca 通道与 SNARE 蛋白相互作用的分子机制以及通过蛋白质磷酸化调节这种相互作用。其次，我们发现类钙调蛋白神经元 Ca 传感器 (nCaS) 蛋白 VILIP-2 通过与钙调蛋白和 CaBP1 相同的结合位点相互作用来调节 Cav2.1 通道，但具有一组独特的调节作用。第三，我们发现 N 端肉豆蔻酰化是 CaBP1 和 VILIP-2 对 Cav2.1 通道的独特调节作用所必需的，并且这些 nCaS 蛋白的 N 端叶赋予了它们调节的特异性。第四，我们发现，Cav2.1通道的nCaS依赖性促进和失活主要负责转染的颈上神经节（SCG）神经元突触中突触传递的短期促进和抑制，这为对短期突触可塑性的分子机制提供了首次见解。最后，我们意外地发现 Ca/钙调蛋白依赖性蛋白激酶 II (CaMKII) 通过与 C 末端结构域上的位点特异性结合来调节 Cav2.1 通道，从而可能定位该激酶以快速响应 Ca 进入和附近蛋白质的磷酸化。在下一个项目期间，我们计划在这些重要进展的基础上： 1. 进一步明确 nCaS 蛋白结合和调节 Cav2.1 通道的分子机制； 2. 确定nCaS蛋白在短期突触可塑性中的功能； 3.探索CaMKII特异性结合Cav2.1通道的信号传导功能； 4.确定突触前CaMKII在突触传递和突触可塑性中的功能作用。这些实验将为突触前 Ca2+ 通道的调节以及这种调节在短期突触可塑性（神经系统中信息编码和传输的基本形式）中的作用提供新的见解。公共健康相关性：神经末梢中的钙通道开始突触传递过程，该过程将信息从一个神经传递到细胞到另一个神经以及肌肉和激素分泌细胞。这些钙通道的正确功能和调节失败会导致癫痫、偏头痛、共济失调和其他神经系统疾病。我们提出的研究将为这些突触前钙通道的调节及其在短期突触可塑性中的功能提供新的见解，这是神经系统中正常编码和信息传输的重要过程，也是神经系统疾病的目标。