Cell biology of osteoclasts II: PSTP1, an adaptor of protein tyrosine phosphatases, as a major component controlling of actin and sealing zone dynamics during bone degradation

为了消化骨骼，破骨细胞需要附着在其表面，通过将富含肌动蛋白的足体重新组织成紧密的带来建立密封区。这些事件是由Src酪氨酸激酶控制的，利用定量蛋白质组学，我们先前已经确定Pro-丝氨酸-苏氨酸磷酸酶相互作用蛋白1(PSTPIP1)是一种Src底物。我们的工作假设是，PSTPIP1通过其F-bar结构域与足体结合，在那里它通过其SH3结构域的PEST-蛋白酪氨酸磷酸酶招募新兵，从而使足体的关键成分失活，从而破坏封闭区的稳定。为了全面了解PSTPIP1在破骨细胞中的功能，有必要1.了解PSTPIP1是如何被招募到足体上的，以及它的活性是如何被调节的；2.确定它的相互作用伙伴，特别是特定的蛋白酪氨酸磷酸酶；3.确定这些磷酸酶的底物，它们可能是封闭区动态的关键结构和调节成分。该项目将结合定量蛋白质组分析和基于视频显微镜的功能研究，应用于siRNA处理的破骨细胞。

To digest bone, osteoclasts need to adhere onto its surface, to build up a sealing zone by reorganizing their actin-rich podosomes into tight belts. These events are controlled by the Src tyrosine kinase, Using quantitative proteomics, we have previously identified the proline-serine-threonine phosphataseinteracting protein 1 (PSTPIP1) as a Src substrate. Our working hypothesis is that PSTPIP1 binds to podosomes via its F-BAR domain where it recruits via its SH3 domain PEST-protein tyrosine phosphatases, which could then inactivate key components of podosomes thereby destabilizing sealing zones. To comprehensively understand PSTPIP1 function in osteoclasts, it will be necessary 1. To understand how PSTPIP1 is recruited onto podosomes and how its activity is regulated, 2. To identify its interacting partners, in particular specific protein tyrosine phosphatases and 3. To identify the substrates of these phosphatases, which are likely key structural and regulatory components of sealing zone dynamics. The project will combine quantitative proteomic analyses and functional studies based on videomicroscopy applied to siRNA treated osteoclasts.