CHARACTERIZATION OF AXONAL TRANSPORT OF A BMP SIGNALING ENDOSOME

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 果蝇幼虫神经肌肉接头（NMJ）的突触生长和功能需要由肌肉源性骨形态发生蛋白（BMP）和神经元BMP受体介导的逆行信号传导。突触末端的信号如何传递到细胞体和细胞核来调节转录尚不清楚。我们发现，I型受体厚静脉（THEK）和II型受体一厢情愿的想法（机智）定位在NMJ突触结，轴突和运动神经元的细胞体的点状结构。这两种受体交通顺行和逆行运动神经元轴突和受体交通的障碍与减少信号通过的途径。除了顺行和逆行交通的I型和II型受体相互独立，我们还检测到逆行共定位囊泡交通的TdR和机智。这种共定位的Wit和TbR的逆行交通在gbb突变体中被破坏，其中信号传导途径是无活性的，并且II型受体Wit被下调。我们提出，共定位的受体交通构成了一个复杂的激活的受体在BMP信号内体和类似的神经营养因子，这种BMP信号内体中继GBB信号从突触末端的细胞体激活下游效应和转录的突触生长所需的基因。 在LSF进行的实验的目的是通过基于FLIM的FRET检测Wit和Tribal在内体中的相互作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Synaptic growth and function of the Drosophila larva neuromuscular junction (NMJ) requires retrograde signaling mediated by muscle-derived Bone Morphogenetic Proteins (BMPs) and neuronal BMP receptors. How signaling at the synaptic terminal is relayed to the cell body and nucleus to regulate transcription is unknown. We find that the type I receptor Thick veins (Tkv) and the type II receptor Wishful thinking (Wit) localize in punctate structures at the NMJ synaptic boutons, axons, and cell body of motoneurons. Both receptors traffic anterogradely and retrogradely in motoneurons axons; and impairment of receptor traffic correlates with a decrease in signaling through the pathway. In addition to anterograde and retrograde traffic of type I and type II receptors independently of each other, we also detect retrograde co-localized vesicular traffic of Tkv and Wit. This co-localized retrograde traffic of Wit and Tkv is disrupted in gbb mutants where the signaling pathway is inactive, and the type II receptor Wit is down regulated. We propose that co-localized receptor traffic constitutes a complex of the activated receptors in a BMP signaling endosome and that similar to neurotrophins, this BMP signaling endosome relays the Gbb signal from the synaptic terminal to the cell body to activate downstream effectors and transcription of genes required for synaptic growth. The goal of the experiments to be performed at LSF is to detect the interaction of Wit and Tkv in endosomes by FLIM-based FRET.