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

PARIANI, A.P.; ALMADA, EVANGELINA; HIGALGO, F.; TONUCCI, F.; FERRETI, A.; FAVRE, CRISTIAN; ZWIRNER, NORBERTO WALTER; LAROCCA, MARÍA CECILIA

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias y 64a Reunión Anual de la Sociedad Argentina de Inmunología; 2017

Sociedad Argentina de Inmunología

The immunological synapse (IS) defines the interface between an immune cell and the cell with which it interacts. For natural killer (NK) cells, the formation of an IS is essential for cell activation and for directed cell secretion of lytic granules content into the target cell. The development of the IS in NK cells involves, after an initial interaction 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 lytic response. AKAP350 is an A-kinase anchoring protein with a main role in the regulation of microtubule dynamics, which, in T-cells, participates in integrin LFA-1 clustering. The aim of our work was to analyze AKAP350 participation in the development of the IS in NK cells. We first characterized AKAP350 expression and localization at the MTOC in NK YTS cells. Control YTS cells and YTS cells with decreased expression of AKAP350 (AKAP350KD) were exposed to erythroleukemia derived KT-86 cells (10:1 ratio) for 3 h and their lytic response analyzed by flow cytometry. AKAP350KD cells lytic activity against their specific targets was significantly decreased (-50%*). Flow cytometry analysis indicated that AKAP350KD cells did not show any alteration at the initial YTS-KT86 conjugate formation or final YTS degranulation. Nevertheless, analysis by confocal microscopy showed that LFA-1 recruitment at the IS was inhibited (-41%*) in AKAP350KD cells. Furthermore, MTOC translocation towards the IS, analyzed as the distance between the YTS centroid and the IS (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 by modulating LFA -1 clustering and MTOC translocation towards the IS. Considering previous results, AKAP350 could modulate these processes by facilitating microtubule/actin cytoskeleton dynamics.