Characterization of the recognition of tumor cells by the natural cytotoxicity receptor, NKp44.
NKp44 is a natural cytotoxicity receptor expressed by human NK cells upon activation. In this study, we demonstrate that cell surface heparan sulfate proteoglycans (HSPGs), expressed by target cells, are involved in the recognition of tumor cells by NKp44. NKp44 showed heparan sulfate-dependent binding to tumor cells; this binding was partially blocked with an antibody to heparan sulfate. In addition, direct binding of NKp44 to heparin was observed, and soluble heparin/heparan sulfate enhanced the secretion of IFNgamma by NK92 cells activated with anti-NKp44 monoclonal antibody. Basic amino acids, predicted to constitute the putative heparin/heparan sulfate binding site of NKp44, were mutated. Tumor cell recognition of the mutated NKp44 proteins was significantly reduced and correlated with their lower recognition of heparin. We previously reported that NKp44 recognizes the hemagglutinin of influenza virus (IV). Nevertheless, the ability of the mutated NKp44 proteins to bind viral hemagglutinin expressed by IV-infected cells was not affected. Thus, we suggest that heparan sulfate epitope(s) are ligands/co-ligands of NKp44 and are involved in its tumor recognition ability.
Hershkovitz
Oren
O
The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, and the Cancer Research Center, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.
Jivov
Sergey
S
Bloushtain
Noga
N
Zilka
Alon
A
Landau
Guy
G
Bar-Ilan
Ahuva
A
Lichtenstein
Rachel G
RG
Campbell
Kerry S
KS
van Kuppevelt
Toin H
TH
Porgador
Angel
A
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001665:Binding Sites; D016466:CHO Cells; D044584:Carcinoma, Ductal / Q000473:pathology; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D000939:Epitopes; D006367:HeLa Cells; D006497:Heparan Sulfate / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics; D007371:Interferon-gamma / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism*; D008024:Ligands; D008297:Male; D008545:Melanoma / Q000473:pathology; D008969:Molecular Sequence Data; D009154:Mutation; D055629:Natural Cytotoxicity Triggering Receptor 2; D010190:Pancreatic Neoplasms / Q000473:pathology; D011471:Prostatic Neoplasms / Q000473:pathology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000939:Epitopes; D006497:Heparan Sulfate; D007136:Immunoglobulins; D007371:Interferon-gamma; D008024:Ligands; D055629:Natural Cytotoxicity Triggering Receptor 2; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins; C112837:NCR2 protein, human