AKAP350 recruits CIP4 to the lytic immune synapse in natural killer cells, conditioning actin reorganization.

PARIANI A; ALMADA E; TONUCCI FM; HIDALGO F; FAVRE C; LAROCCA MC

Congreso; Reunion cientifica anual conjunta de SAIC, SAI Y SAFIS; 2018

Lytic Immune synapse (LIS) is defined as the contact of the natural killer (NK) or cytotoxic T cells with its target cell and the subsequent directional secretion of lytic granules necessaries for target cell death. The development of the IS in NK cells involves, after an initial interaction with the target cell, actin remodeling and NK integrin LFA-1 clustering at the interaction site. CIP4 is a regulator of actin polymerization, which is recruited to the MTOC at the LIS in NK cells, having a crucial role in the lytic response. AKAP350 is an A-kinase anchoring protein involved in the regulation of microtubule dynamics, which recruits CIP4 to the MTOC in migratory cells. Our previous results indicate that AKAP350 expression conditions LFA clustering and overall lytic response in NK cells. The aim of our work was to evaluate AKAP350 participation in the recruitment of CIP4 to the MTOC and the LIS and actin reorganization in NK cells. YTS NK cells with decreased expression of AKAP350 (AKAP350KD) were exposed to erythroleukemia derived KT-86 cells (2:1 ratio) for 30 minutes and CIP4 and actin distribution was analyzed by immunofluorescence confocal microscopy. AKAP350 knock down lead to decreased CIP4 localization at the MTOC (-40%*) and at the LIS (-35%*). Concomitantly, actin accumulation at the LIS was impaired in AKAP350KD cells (-66%*). Western blot analyzis of MTOC enriched NK fractions also showed decreased CIP4 localization in AKAP350KD cells (-43%). Our results suggest that, in NK cells, AKAP350 is involved in the reorganization of the actin cytoskeleton at the LIS by regulating CIP4 localization at the MTOC and its polarization during the LIS development. *p