Molecular Mechanisms Regulating BDNF Release

BDNF 诱导中枢神经元的结构和功能变化，以调节突触功效；我们的目标 是确定调节 BDNF 在突触靶向和释放的分子机制，以调节 神经传递。 BDNF 被合成为前体，proBDNF，分类到受调节的分泌途径， 并以依赖活动的方式释放。在突触处，proBDNF 可以选择性地与 p75 结合， 诱导LTD，并可能降低树突棘密度和树突复杂性。如果 proBDNF 转换为 分泌小泡或突触间隙中成熟的BDNF，TrkB被选择性激活以增强突触 传输并促进轴突分支和树突生长。因此，调节机制 将 proBDNF 转化为成熟 BDNF，并调节向树突或轴突的运输，关键性调节 结构和功能神经元的可塑性。我们已经培育出表达 HA 标记的 BDNF 的敲入小鼠 显着增强内源性 BDNF 的检测。我们还鉴定了细胞内伴侣， 包括分拣蛋白和其他结合 proBDNF 的分拣蛋白家族成员。通过这些工具，可以实现三个相互关联的工具 提出的目标是：（1）使用来自 BDNF-HA 小鼠的神经元，确定 proBDNF 是否转化为 成熟的 BDNF 发生在分选到分泌囊泡期间，或囊泡融合和释放之后。我们 假设 BDNF 转换的位置可能因神经元亚型而异。 (2) 我们将确定 sortilin 家族成员陪伴 proBDNF 进入组成型或调节型分泌途径，并 树突或轴突。我们假设不同的分拣蛋白成员将细胞内运输引导至不同的 亚细胞区室，递送至突触，并调节成熟 BNDF 的裂解。使用 BDNF-HA 小鼠，以及不同伴侣的急性沉默，我们将评估发育调控的变化 proBDNF/成熟 BDNF 释放的比率，以及 BDNF 的逆行和顺行运输 同工型。 (3)我们将产生敲入小鼠以有条件地删除相关的分拣蛋白家族成员。这些 动物将使我们能够剖析选定的 BDNF 伴侣在调节 BDNF 水平中的作用，目标是 轴突或树突，以及对完整的出生后大脑中神经元形态和连接的影响。 相关性（参见说明）： 该项目确定了调节 BDNF 释放、调节形态和连接的机制 海马和皮质神经元；这些过程的失调会导致神经发育 疾病。减少 BDNF 释放的人类 SNP 会导致小鼠出现焦虑和抑郁症状，并且 与这些人类疾病相关。额叶连接异常导致焦虑 anri 自闭症 ths mfjchanlRms iriftifiert hfirR will vieiri npw tarnRt.¿;抗风湿病中的固定胺

BDNF induces structural and functional changes in central neurons to modulate synaptic efficacy; our goal is to identify molecular mechanisms that regulate BDNF targeting and release at synapses to modulate neurotransmission. BDNF is synthesized as a precursor, proBDNF, sorted to a regulated secretory pathway, and released in an activity-dependent manner. At the synapse, proBDNF can bind selectively to p75 to induce LTD, and potentially reduce spine density and dendritic complexity. If proBDNF is converted to mature BDNF in the secretory vesicle or synaptic cleft, TrkB is selectively activated to enhance synaptic transmission and promote axonal branching and dendritic growth. Thus, mechanisms that regulate conversion of proBDNF to mature BDNF, and regulate trafficking to dendrites or axons critically modulate structural and functional neuronal plasticity. We have generated knock-in mice expressing HA-tagged BDNF to markedly enhance detection of endogenous BDNF. We have also identified intracellular chaperones, including sortilin, and other sortilin family members that bind proBDNF. With these tools, three interrelated aims are proposed: (1) Using neurons from the BDNF-HA mouse, identify if conversion of proBDNF to mature BDNF occurs during sorting to secretory vesicles, or following vesicle fusion and release. We postulate that the location of BDNF conversion may differ among neuronal subtypes. (2) We will identify the sortilin family members that chaperone proBDNF to the constitutive or regulated secretory pathways, and to dendrites or axons. We posit that different sortilin members direct intracellular trafficking to different subcellular compartments, delivery to the synapse, and regulate cleavage to mature BNDF. Using BDNF-HA mouse, and acute silencing of different chaperones, we will assess the developmentally regulated changes in the ratio of proBDNF/mature BDNF release, and in retrograde and anterograde traffiking of BDNF isoforms. (3) We will generate knock-in mice to conditionally delete relevant sortilin family members. These animals will permit us to dissect the roles of select BDNF chaperones in regulating BDNF levels, targeting to axons or dendrites, and effects on neuronal morphology and connectively in the intact, postnatal brain. RELEVANCE (See instructions): This project identifies mechanisms that regulate BDNF release, and modulates morphology and connectivity of hippocampal and cortical neurons; disregulation of these processes contributes to neurodevelopmental disease. A human SNP that reduces BDNF release results in anxiety and depressive symptoms in mice, and correlates with these human diseases. Abnormal frontolimbic connectivity underiies conditions of anxiety anri autism Ths mfjchanlRms irifintifiert hfirR will vieiri npw tarnRt.¿; fnr fixaminatinn in thRSfi riiseases