title: Residues Met76 and Gln79 in HLA-G alpha1 domain involve in KIR2DL4 recognition.
abstract: Human leukocyte antigen-G (HLA-G) has long been speculated as a beneficial factor for a successful pregnancy for its restricted expression on fetal-maternal extravillous cytotrophoblasts and its capability of modulating uterine natural killer cell (uNK) function such as cytotoxicity and cytokine production through NK cell receptors. HLA class I alpha1 domain is an important killer cell Ig-like receptor (KIR) recognition site and the Met76 and Gln79 are unique to HLA-G in this region. NK cell receptor KIR2DL4 is a specific receptor for HLA-G, yet the recognition site on HLA-G remains unknown. In this study, retroviral transduction was applied to express the wild type HLA-G (HLA-wtG), mutant HLA-G (HLA-mG) on the chronic myelogenous leukemia cell line K562 cells and KIR2DL4 molecule on NK-92 cells, respectively. KIR2DL4-IgG Fc fusion protein was generated to determine the binding specificity between KIR2DL4 and HLA-G. Our results showed that residue Met76, Gln79 mutated to Ala76,79 in the alpha1 domain of HLA-G protein could affect the binding affinity between KIR2DL4 and HLA-G, meanwhile, the KIR2DL4 transfected NK-92 cells (NK-92-2DL4) showed a considerably different cytolysis ability against the HLA-wtG and HLA-mG transfected K562 targets. Taken together, our data indicated that residue Met76 and Gln79 in HLA-G alpha1 domain plays a critical role in the recognition of KIR2DL4, which could be an explanation for the isoforms of HLA-G, all containing the a1 domain, with the potential to regulate NK functions.
authors.affiliation: Laboratory of Immunogenetics, Shanghai Second Medical University, 280 South Chongqing Road, Shanghai 200025, China.
authors.forename: Wei Hua
authors.initials: WH
authors.lastname: Yan
authors.forename: Li An
authors.initials: LA
authors.lastname: Fan
mesh_terms: D001665:Binding Sites; D045744:Cell Line, Tumor; D003602:Cytotoxicity, Immunologic; D005973:Glutamine / Q000235:genetics*; D006680:HLA Antigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008715:Methionine / Q000235:genetics*; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011971:Receptors, Immunologic / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D054340:Receptors, KIR; D054345:Receptors, KIR2DL4; D014162:Transfection
chemical_list: D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; C515079:KIR2DL4 protein, human; D011971:Receptors, Immunologic; D054340:Receptors, KIR; D054345:Receptors, KIR2DL4; D005973:Glutamine; D008715:Methionine