Regulation of Cellular Responsiveness to BDNF

细胞对 BDNF 反应的调节

• 批准号: 7009577
• 负责人: BRUCE K KRUEGER
• 金额: $ 26.83万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7009577
• 关键词: action potentials; biological signal transduction; brain derived neurotrophic factor; calcium ion; genetic regulation; genetic regulatory element; genetic transcription; growth factor receptors; laboratory mouse; protein isoforms; transcription factor

DESCRIPTION (provided by applicant): The neurotrophin, brain derived neurotrophic factor (BDNF), plays a critical role in brain development and function by regulating neuron survival and synaptic plasticity. Defects in BDNF signaling may lead to developmental, neurodegenerative and psychiatric disorders. Cellular responses to BDNF are mediated by the tyrosine receptor kinase, trkB, and their magnitude is determined by the relative levels of active, full-length trkB, and of truncated trkB isoforms, which act as dominant-negative inhibitors of BDNF signaling. Preliminary studies in cortical neurons revealed that expression of full-length trkB, but not that of truncated trkB, is stimulated by membrane depolarization via increased levels of intracellular Ca2+. Ca2+ was also found to exert opposing effects on the two promoters of the trkB gene (TRKB), suggesting that promoter usage regulates trkB isoform expression. These observations have led to the working hypothesis: TrkB isoform expression and consequently, neuronal responsiveness to BDNF, is regulated by Ca2+-dependent TRKB transcription. The mechanism by which Ca2+ differentially regulates the TRKB promoters will be studied using recombinant DNA technology to identify the Ca2+-dependent regulatory elements in TRKB and the transcription factors hat interact with them. The role of Ca2+-mediated promoter utilization in regulating the differential expression f full-length and truncated trkB will be studied by measuring the depolarization-induced expression f full-length and truncated trkB mRNA with promoter-specific 5'-untranslated sequences. In order to place Ca2+-dependent TRKB regulation in a more physiological context, we will investigate the ability of patterns of electrically evoked Ca2+ transients, which mimic in vivo neuronal activity, to differentially activate the TRKB promoters and differentially drive expression of full-length and truncated trkB isoforms. The long-term goal of this research is to elucidate the mechanisms by which Ca2+ regulates expression of trkB isoforms and, thus, modulates neuronal responsiveness to BDNF in the developing, adult and diseased brain.

描述（由申请人提供）：神经营养蛋白，脑衍生的神经营养因子（BDNF），通过调节神经元的存活和突触可塑性，在脑发育和功能中起关键作用。 BDNF信号传导的缺陷可能导致发育，神经退行性和精神疾病。细胞对BDNF的反应是由酪氨酸受体激酶，TRKB介导的，它们的幅度由活性，全长TRKB的相对水平和截短的TRKB同工型确定，这些水平是BDNF信号传导的主要阴性抑制剂。 在皮质神经元中的初步研究表明，全长TRKB的表达（但没有截短的TRKB的表达）是通过膜去极化通过增加的细胞内Ca2+的水平来刺激的。还发现Ca2+对TRKB基因（TRKB）的两个启动子（TRKB）的启动子产生相反的影响，这表明启动子的使用调节TRKB同工型表达。这些观察结果导致了工作假设：TRKB同工型表达，因此，对BDNF的神经元反应性受CA2+依赖性TRKB转录调节。 将使用重组DNA技术研究Ca2+差异调节TRKB启动子的机制，以识别TRKB中Ca2+依赖性的调节元件，而转录因子HAT与它们相互作用。 Ca2+介导的启动子利用在调节差异表达F全长和截断的TRKB中的作用将通过测量去极化诱导的表达F全长和截短的TRKB mRNA，并使用启动子特异性的5'-非反式序列进行研究。 为了在更加生理的环境中放置Ca2+依赖性TRKB调节，我们将研究电诱发的Ca2+瞬变模式的能力，这些瞬态模仿体内神经元活性，以差异激活TRKB启动子，并差异地驱动全长和截断的TRKB同工型的表达。 这项研究的长期目标是阐明Ca2+调节TRKB同工型表达的机制，从而调节发育中的成人和患病大脑中对BDNF的神经元反应性。