Krummel Matthew F, Friedman Rachel S, Jacobelli Jordan
Department of Pathology, UCSF, 513 Parnassus Avenue, Box 0511, San Francisco, CA 94143, USA.
Department of Immunology, National Jewish Health, 1400 Jackson Street, K501, Denver, CO 80206, USA.
Curr Opin Cell Biol. 2014 Oct;30:9-16. doi: 10.1016/j.ceb.2014.05.003. Epub 2014 Jun 3.
T cells are charged with surveying tissues for evidence of their cognate foreign antigens. Subsequently, they must navigate to effector sites, which they enter through the process of trans-endothelial migration (TEM). During interstitial migration, T cells migrate according to one of two modes that are distinguished by the strength and sequence of adhesions and the requirement for Myosin-IIA. In contrast during TEM, T cells require Myosin-IIA for the final process of pushing their nucleus through the endothelium. A generalized model emerges with dual roles for Myosin-IIA: This motor protein acts like a tensioning or expansion spring, transmitting force across the cell cortex to sites of surface contact and also optimizing the frictional coupling with substrata by modulating the surface area of the contact. The phosphorylation and deactivation of this motor following TCR engagement can allow T cells to rapidly alter the degree to which they adhere to surfaces and to switch to a mode of interaction with surfaces that is more conducive to forming a synapse with an antigen-presenting cell.
T细胞负责在组织中搜寻其同源外来抗原的证据。随后，它们必须导航至效应器部位，通过跨内皮迁移（TEM）过程进入这些部位。在间质迁移过程中，T细胞根据两种模式之一进行迁移，这两种模式的区别在于黏附的强度和顺序以及对肌球蛋白-IIA的需求。相比之下，在TEM过程中，T细胞在将细胞核推过内皮的最终过程中需要肌球蛋白-IIA。由此出现了一个关于肌球蛋白-IIA双重作用的通用模型：这种运动蛋白就像一个张紧或拉伸弹簧，将力通过细胞皮层传递到表面接触部位，并通过调节接触表面积来优化与底物的摩擦耦合。TCR参与后这种运动蛋白的磷酸化和失活可使T细胞迅速改变其与表面黏附的程度，并切换到一种与表面相互作用的模式，这种模式更有利于与抗原呈递细胞形成突触。
