Regulation of TMEM55A/B-dependent positioning of lysosomes

TMEM55A/B 依赖性溶酶体定位的调节

• 批准号: 388482877
• 负责人: Professor Dr. Markus Damme
• 金额: --
• 依托单位: Biochemisches Institut
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/388482877?language=en
• 关键词: Regulation; TMEM55A; dependent; positioning; lysosomes

Lysosomes are highly dynamic organelles. Their spatio-temporal distribution within a cell depends on active transport mainly driven by microtubule motors such as kinesins and dynein and the interaction of motor proteins with cargoes is mediated by a sophisticated system of membrane-proteins present on cargo vesicles. TMEM55B, a lysosomal double-spanning transmembrane protein with a large cytosolic domain, is such a protein that mediates motor-protein interaction and thereby regulates lysosomal positioning. We figured out an essential role of TMEM55B for proper positioning of lysosomes in neurons by analyzing Tmem55b knockout mice that depends on the scaffold protein JIP4. Tmem55b knockout mice accumulate lysosomes in the axon initial segment. While a functional role of TMEM55B in the dynein-driven retrograde transport was suggested previously, we propose an important role in the anterograde transport in neurons. We plan to examine the directional transport of lysosomes in neurons from Tmem55b knockout mice under basal conditions and upon forcing anterograde- and retrograde transport, as well as in neurons in a newly developed Caenorhabditis elegans knockout worm to clearly decipher TMEM55B`s function in lysosomal positioning. TMEM55B has a paralogue (TMEM55A) and both might partially compensate for each other. We plan to validate TMEM55B and TMEM55A-interacting proteins, previously identified by co-immunoprecipitation and mass spectroscopy and determine their contribution on intracellular sorting of TMEM55A and TMEM55B and lysosomal positioning. Finally we plan to investigate the dependence of different posttranslational modifications of TMEM55B we determined previously on each other and on cellular trafficking of TMEM55B and lysosomal positioning. In summary, our experiments will provide a detailed understanding of TMEM55B on lysosomal positioning with an emphasis on neuronal transport and possible other, positioning independent, functions in vitro and in vivo.

溶酶体是高度动态的细胞器。它们在细胞内的时空分布取决于主要由微管马达如驱动蛋白和动力蛋白驱动的主动运输，马达蛋白与货物的相互作用由货物囊泡上存在的复杂的膜蛋白系统介导。TMEM 55 B是一种具有大胞质结构域的溶酶体双跨膜蛋白，是介导马达-蛋白相互作用从而调节溶酶体定位的蛋白质。我们通过分析依赖于支架蛋白JIP 4的Tmem 55 b敲除小鼠，发现了TMEM 55 B对于溶酶体在神经元中的正确定位的重要作用。tmem 55 b敲除小鼠在轴突起始段中积累溶酶体。虽然TMEM 55 B在动力蛋白驱动的逆行转运中的功能作用以前被提出，但我们提出了在神经元的顺行转运中的重要作用。我们计划研究在基础条件下和强制顺行和逆行运输时，Tmem 55 b敲除小鼠神经元中溶酶体的定向运输，以及新开发的秀丽隐杆线虫敲除蠕虫中的神经元中的溶酶体定向运输，以清楚地破译TMEM 55 B在溶酶体定位中的功能。TMEM 55 B具有paramount（TMEM 55 A），并且两者可以部分地相互补偿。我们计划验证TMEM 55 B和TMEM 55 A相互作用的蛋白质，以前通过免疫共沉淀和质谱鉴定，并确定它们对TMEM 55 A和TMEM 55 B的细胞内分选和溶酶体定位的贡献。最后，我们计划研究我们先前确定的TMEM 55 B的不同翻译后修饰对彼此以及对TMEM 55 B的细胞运输和溶酶体定位的依赖性。总之，我们的实验将提供TMEM 55 B对溶酶体定位的详细理解，重点是神经元转运和可能的其他定位独立的体外和体内功能。