Regulation of microtubule-organizing center orientation and actomyosin cytoskeleton rearrangement during immune interactions.

The reorganization of membrane, cytoskeletal and signaling molecules during immune interactions is critical for the generation of immune response. At the initiation of the T cell-antigen presenting cell (APC) interaction, antigen-independent weak adhesion forces allow the scanning of the APC surface by the T cell receptor for specific antigens. The stabilization of T cell-APC conjugates involves the segregation of membrane and intracellular signaling proteins, driven by reorganization of membrane microdomains and cytoskeletal changes. In early T cell-APC cognate interactions, the microtubular cytoskeleton undergoes drastic changes that lead to microtubule-organizing center (MTOC) reorientation to the vicinity of the cell-cell contact area. Recent data on the dynamics of MTOC redistribution and its influence in T cell-APC conjugate stabilization, together with the description of an increasing number of signaling molecules associated to this complex, underscore the key role of MTOC translocation in the T cell response. We focus on the mechanisms that control the early MTOC reorientation during T cell-APC interaction and the relevance of this process to T cell activation.