The role of SWAP-70 in mast cell adhesion, migration and F-actin cytokeletal rearrangements

肥大细胞(MC)的迁移和黏附对其功能至关重要，必须对其进行适当的调节，并控制F-肌动蛋白的动态和黏附受体。早些时候，我们证明了F-肌动蛋白结合蛋白SWAP-70是MC迁移和黏附的重要调节器。在第一个资助期，我们发现了SWAP-70控制F-肌动蛋白重排的一种新的相互作用和两种新的机制：(I)与F-肌动蛋白切割蛋白cofilin的直接物理相互作用和对其活性的限制，以及(Ii)SWAP-70对肌动蛋白细丝的捆绑和稳定。此外，我们进一步表征了SWAP-70对整合素的控制，并显示了它们与SWAP-70的物理相互作用。此外，我们积累了迄今为止尚不为人所知的钙粘附素在MC中的功能的证据，即E-CDH，并且正在产生一种MC特异性E-CDH缺陷小鼠品系。现在有迹象表明，SWAP-70和它唯一密切相关的蛋白质DEF6的功能部分重叠。SWAP-70-/-Def6-/-菌株已经产生，其MC现在将在体内和体外进行分析。此外，基于Mcpt5-Cre在SWAP-70小鼠中的表达，产生了MC特异性的SWAP-70缺陷小鼠品系。这种新的菌株将消除其他SWAP-70缺陷细胞类型的旁观者效应。总之，在第二个资助期，我们将进一步分析SWAP-70对整合素的调控，探索新发现的SWAP-70对微丝蛋白的调控，将确定E-CDH在MC中的功能和SWAP-70在MC中的作用，并将包括分析DEF6及其与MC中SWAP-70的关系。通过这项计划，我们希望对我们对管理MC迁移和黏附的中心途径和机制的理解做出重大贡献。

Migration and adhesion of mast cells (MCs) is essential for their function and must be properly regulated, F-actin dynamics and adhesion receptors are to be controlled. Earlier we demonstrated the F-actin binding protein SWAP-70 as an important modulator of MC migration and adhesion. In the 1st funding period we identified a novel interaction and two novel mechanisms with which SWAP-70 controls F-actin rearrangements: (i) direct physial interaction with the F-actin severing protein cofilin and restriction of its activity, and (ii) bundling and stabilization of actin filaments by SWAP-70. Also, we further characterized SWAP-70 control of integrins and showed their physical interaction with SWAP-70. Furthermore, we accumulated evidence for a hitherto largely unknown function of cadherins, i.e. E-Cdh, in MCs and a MCspecific E-Cdh deficient mouse strain is being generated. Indications now emerged for partially overlapping functions of SWAP-70 and its only closely related protein, DEF6. The Swap-70-/- Def6-/- strain was generated and its MC will now be analyzed in vivo and in vitro. In addition, a MC-specific SWAP-70 deficient mouse strain was generated based on Mcpt5-Cre expression in Swap-70floxed mice. This new strain will eliminate bystander effects of other SWAP-70 deficient cell types. Together, in the 2nd funding period, we will further analyze control of integrins by SWAP-70, will explore the newly identified SWAP-70 control of cofilin, will determine the function of E-Cdh in MCs and the role of SWAP-70 therein, and will include analysis of DEF6 and its relationship to SWAP-70 in MCs. With this program we expect to contribute significantly to our understanding of central pathways and mechanisms that govern MC migration and adhesion.