AKAP350 regulates natural killer cytotoxcity by conditioning cell polarization at the immune synapse.

FAVRE C; TONUCCI F; ZWIRNER N; FERRETTI AC; PARIANI A; LAROCCA MC; HIDALGO F; ALMADA E

Buenos Aires

Congreso; Reunion cientifica anual conjunta de Sociedades de Biociencias; 2017

The immunological synapse (IS) defines the interface between animmune cell and the cell with which it interacts. For natural killer(NK) cells, the formation of an IS is essential for cell activation andfor directed cell secretion of lytic granules content into the targetcell. The development of the IS in NK cells involves, after an initialinteraction with the target cell, the formation of an actin ring at the IS,and the repositioning of the microtubule organizing center (MTOC)towards this site, which conditions the specificity of the final lyticresponse. AKAP350 is an A-kinase anchoring protein with a mainrole in the regulation of microtubule dynamics, which, in T-cells, participatesin integrin LFA-1 clustering. The aim of our work was toanalyze AKAP350 participation in the development of the IS in NKcells. We first characterized AKAP350 expression and localizationat the MTOC in NK YTS cells. Control YTS cells and YTS cells withdecreased expression of AKAP350 (AKAP350KD) were exposed toerythroleukemia derived KT-86 cells (10:1 ratio) for 3 h and their lyticresponse analyzed by flow cytometry. AKAP350KD cells lytic activityagainst their specific targets was significantly decreased (-50%*).Flow cytometry analysis indicated that AKAP350KD cells did notshow any alteration at the initial YTS-KT86 conjugate formation orfinal YTS degranulation. Nevertheless, analysis by confocal microscopyshowed that LFA-1 recruitment at the IS was inhibited (-41%*)in AKAP350KD cells. Furthermore, MTOC translocation towardsthe IS, analyzed as the distance between the YTS centroid and theIS (dc) minus the distance between the MTOC and the IS (dMTOC),was severely impaired by the decrease in AKAP350 expression.Our results indicate that AKAP350 conditions NK lytic capacity bymodulating LFA -1 clustering and MTOC translocation towards theIS. Considering previous results, AKAP350 could modulate theseprocesses by facilitating microtubule/actin cytoskeleton dynamics.Keywords: NK cells, AKAP350, MTOC, LFA-1, Cytotoxicity