Mechanistic analysis of activity-dependent BMP/TGF-beta release at a model synaps

描述（由申请人提供）：在模型突触处活性依赖性BMP/TGF β释放的机制分析细胞如何使广泛使用的细胞间信号传导途径的信号输出多样化？少数保守的生长因子途径在整个生命过程中介导细胞之间的通信。然而，值得注意的是，这些通路的信号转导结果与发育和细胞环境密切相关。我们将研究BMP/TGF β通路的信号传导特异性。该途径在果蝇NMJ中发挥许多独立的功能。特别是，它调节NMJ形态生长和神经递质释放。我们目前的证据表明，细胞来源的BMP配体GBB区分这两种途径。我们提出了一个模型，其中的单通道跨膜蛋白Criminal是一个分选受体的BMP致密的核心囊泡在调节分泌途径。我们认为：（1）BMP的活性依赖性释放促进神经传递;（2）CRYMPLATE定义了神经元衍生的配体库。BMP/TGF β家族成员在哺乳动物神经元中突触定位并受到活性依赖性释放。然而，负责其定位到致密核心囊泡的细胞机制是不透明的。CRYSTAL将代表在任何系统中鉴定的第一个BMP/TGF β致密核心囊泡分选受体。鉴于临床上的兴趣，在确定工具，选择性地靶向突触功能的生长因子信号传导途径，一个机制的理解criterion及其哺乳动物同源物将是显着的兴趣。

DESCRIPTION (provided by applicant): Mechanistic analysis of activity-dependent BMP/TGF¿ release at a model synapse How do cells diversify signaling outputs of widely used intercellular signaling pathways? A handful of conserved growth factor pathways mediate communication between cells throughout life. Yet remarkably, the signaling outcomes of these pathways are finely tuned to developmental and cellular context. We will investigate signaling specificity of the BMP/TGF¿ pathway. This pathway serves a number of independent functions at the Drosophila NMJ. In particular, it regulates both NMJ morphological growth and neurotransmitter release. We present evidence that the cellular source of the BMP ligand Gbb discriminates between these two pathways. We propose a model in which the single-pass transmembrane protein Crimpy is a sorting receptor for the BMP for dense core vesicles in the regulated secretory pathway. We argue that (1) activity-dependent re- lease of the BMP promotes neurotransmission and (2) Crimpy defines the neuron-derived ligand pool. BMP/TGF¿ family members are synaptically localized and subject to activity-dependent release in mammalian neurons. However, the cellular mechanisms responsible for their localization to dense core vesicles are opaque. Crimpy would represent the first BMP/TGF¿ dense core vesicle sorting receptor identified in any system. Given clinical interest in identifying tools to selectively target synaptic functions of growth factor signaling pathways, a mechanistic understanding of Crimpy and its mammalian homologs will be of significant interest.