PSTPIP1 controls immune synapse stability in human T-cells

Publication date: Available online 9 February 2018
Source:Journal of Allergy and Clinical Immunology
Author(s): W.J.M. Janssen, V. Grobarova, J. Leleux, C.H. Jongeneel, M. van Gijn, J.M. van Montfrans, M. Boes
BackgroundPSTPIP1 is a cytosolic adaptor protein involved with T-cell activation, differentiation, and migration. Upon cognate T-cell contact, PSTPIP1 is recruited to surface-expressed CD2, where it regulates f-actin remodeling. An immune synapse (IS) is thereby rapidly formed, consisting of TCR clusters surrounded by a ring of adhesion molecules including CD2.ObjectiveFrom genetic screening of primary immunodeficiency patients, we identified two mutations in PSTPIP1, R228C and T274M which we further characterized in primary patient T-cells.MethodsF-actin dynamics were assessed in patient and healthy control primary T-cells by use of FACS. HEK293T and Jurkat cells were transfected with R228C, T274M and WT PSTPIP1 in order to visualize f-actin in immune synapse formation. CD2-PSTPIP1 association was quantified through immunoprecipitation assays.ResultsThe patients presented with immunodeficiency without signs of auto-inflammation. The R228C patient had expansion of mostly naive phenotype T-cells and few memory T-cells; the T274M patient had 75% reduction in CD4 T-cells that were predominantly of memory subset.We observed f-actin polymerization defects in both PSTPIP1 patient T-cells, most notably T274M. Capping of CD2-containing membrane microdomains was disrupted. Analysis of IS formation using Jurkat T-cell transfectants revealed a reduction in f-actin accumulation at the IS, again especially in T274M PSTPIP1 cells. Patient T274M T-cells migrated spontaneously at increased speed as assessed in a 3D collagen matrix, while TCR crosslinking induced a significantly diminished calcium flux.ConclusionsWe propose that PSTPIP1 T-cell differentiation defects are caused by defective control of f-actin polymerization. A pre-activated polymerized f-actin status, as seen in PSTPIP1-T274M T-cells, appears particularly damaging. PSTPIP1 controls IS formation and cell adhesion, through its function as orchestrator of the f-actin cytoskeleton.



http://ift.tt/2Bnbesy