engleski

The development and analysis of NKG2D k.o. mouse

NKG2D is an activating receptor that is involved in the innate and adaptive immune response to various forms of cellular stress (infections, heat shock, etc.) and tumor transformation. In mice, it is expressed on NK, NKT and T (activated and memory CD8+ ab and some gd) cells. NKG2D is a transmembrane type II glycoprotein, encoded by a gene situated within the NK complex of the mouse chromosome 6, which binds different, mostly stress-induced MHC class I-like molecules (MULT-1, H60 and Rae 1 family) on wide variety of cell types. Although the role of NKG2D has been intensively investigated in different models (viral infections, tumor immunosurveillance, autoimmunity, etc.), to address more specific questions on the role of NKG2D in the development, homeostasis and effector functions of the immune system the use of a genetic approach seems to be preferable. Therefore, we have generated NKG2D knock out mouse strain by targeting of NKG2D in Bruce 4 (C57BL/6) embryonic stem (ES) cells. Following the selection and screening procedure, we have identified several ES cell clones positive for the homologous recombination. Upon the microinjection of the clones we have obtained several chimeras that have given germ-line transmission of the mutation. The flow cytometry analysis of CD8+ T and NK cells isolated from NKG2D k.o. mice has revealed complete absence of the NKG2D receptor. However, we haven't observed any abnormalities either in the development of T cells or in the presence of mature T cell subpopulations at the periphery of NKG2D k.o. mice. Unexpectedly, NKG2D mutant mice have shown enhanced resistance to early MCMV infection either with tissue culture grown m157 MCMV (4d p.i.) or more virulent SGV virus. Flow cytometric analysis of NK cells has reviled that absence of NKG2D affects the NK cell development (reduced number of c-Kit+, CD 51+ and Ly49A+ NK cells). We have also observed increased number of mature KLRG1+ NK cells on the periphery.

Embryonic stem cells; Gene targeting; Cre/loxP recombination system; NK cell development; NKG2D; NKG2D deficient mice

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