NCR3 explained

Natural cytotoxicity triggering receptor 3 is a protein that in humans is encoded by the NCR3 gene.^{[1] [2] [3]} NCR3 has also been designated as CD337 (cluster of differentiation 337) and as NKp30. NCR3 belongs to the family of NCR membrane receptors together with NCR1 (NKp46) and NCR2 (NKp44).^[4]

Identification

NKp30 receptor was first identified in 1999. According to Western blot analysis specific monoclonal antibodies reacted with 30kDa molecule, therefore was the protein named NKp30.^[5]

Structure

Gene for NKp30 is located in the MHC class III region of the human MHC locus and encodes 190 amino acid long type I transmembrane receptor which belongs to immunoglobulin super family (IgSF).^[6] NKp30 has a mass of 30 kDa and includes one Ig-like extracellular domain which is 138 amino acids long, a 19 amino acid transmembrane (TM) domain and a 33 amino acid cytoplasmic tail.^[7] The Ig-like domain consists of 2 antiparallel beta-sheets linked by a disulphide bond.^[8] The extracellular domain contains two potential sites for N-linked glycosylation involved in ligand binding. The TM domain contains a positivelly charged arginine residue, which associates with negatively charged aspartate in TM domain of ITAM adaptor molecules CD3ζ and FCεRIγ. This is a common feature of other NK cell activating receptors as well.^[9] Accordingly the cytoplasmic tail lacks typical ITAM consensus sequence.

Splicing variants

We can find six different splicing variants on the cell surface. NKp30a, NKp30b and NKp30c encode molecules with extracellular V-type Ig domain. NKp30d, NKp30e and NKp30f encode extracellular C-type Ig domain. Splicing variants also differ in their cytosolic intracellular domains depending on the translation of variants of exon 4 (NKp30a,b or c).

The distribution of splicing variants of NKp30 varies in tissues and results in different NK cell responses. NKp30a/b engagement stimulates the release of high amounts of IFN-γ, whereas activation of NKp30c induces IL-10 production and only small amounts of IFN-γ. First two are therefore considered as immunostimulatory isoforms which enhance Th1 immune response, while NKp30c mediates immunosuppressive signaling most likely because of reduced association with CD3ζ adaptor after cross-linking with ligand.

Gastrointestinal stromal tumor patients who express NKp30c isoform have worse prognosis compared with patients expressing other isoforms, mainly as a consequence of NK cell immunosuppressive character.^[10]

Expression

NCR3 is expressed mainly on cytoplasmic membrane of mature NK cells and functions as an activating receptor of NK cells. However it is also expressed on surface of CD8+ T cells, γδ T cells with Vδ1 TCR and ILC2. The presence of IL-15 stimulates the expression of NKp30+ CD8+ T cells with anti-tumor activity.^[11] Expression of NKp30 in γδ T cells is induced by IL-2 or IL-15.^[12] After progesteron stimulation NKp30 can be found on the cytoplasmic membrane of endometrial epithelial cells as well.

Function

NKp30 plays a major role in NK anti-tumor response and immunosurveillance, mainly by activating NK cell cytotoxicity and cytokine secretion.^[13] Direct killing happens similarly to other natural cytotoxicity receptors (NCRs) such as NKp44 and NKp46.^[14] NCR3 has a wide range of non-MHC ligands secreted or expressed by cancer or virus-infected cells, e.g. to heparan sulfate glycosaminoglycans (HS GAGs) and B7-H6.^[15]

Heparan sulfate epitopes are in healthy tissue as well as on tumor cells, where HS GAGs are changed or differ in ligands (HMGB1, S100A8/A9) in contrast to healthy tissue. In addition, interaction of NCR with HS GAGs can facilitate binding to other cellular ligands. Thus via heparan sulfate epitopes NCRs can bind to the same ligands and exert similar reactions and at the same time also have their own unique interacting partners. It is also known that heparan sulfate epitopes lead to better signaling through growth factor receptors, NCRs could be thus evolved to recognize unusual HS GAGs on malignant cells as transformed cell patterns.

Ligation of NKp30 and intracellular protein HLA-B-associated transcript 3 (BAT3) released by tumour cells to extracellular matrix results in NK and dendritic cell cross-talk.

Human cytomegalovirus protein pp65 is another ligand of NKp30. The ligation leads to disruption of the interaction between NKp30 and CD3ζ and thus decreases the activation of NK cells and its cytotoxicity. This is a mechanism of HMCV to evade NK cell surveillance.

Patients with primary Sjögren's syndrome express higher levels of NKp30+ NK cells (and its ligation with B7-H6 expressed in salivary glands) in comparison to healthy controls.

NKp30 and dendritic cells

Immature dendritic cells can be lysed upon stimulation of NKp30 on NK cells. Accordingly. patients with acute myeloid leukemia (AML), who often show downregulation in NKp30 expression, were incapable of effectively lysing both autologous and allogeneic immature dendritic cells. The ability of NK cells to kill immature dendritic cells may serve to check the quality of dendritic cell maturation process. Interestingly at the same time immunostimulatory capacity of dendritic cells can be enhanced via interaction with NKp30 with ligands expressed on immature dendritic cells. Upon such stimulation NK cells produce TNFα which is capable of inducing dendritic cell maturation.

NCR3 during pregnancy

Uterine NK cells (uNK) are the most abundant lymphocyte population in uterus during pregnancy on the maternal-fetal interface. These cells are responsible for angiogenesis and vascular remodelling in trophoblast.^{[16] [17]} uNK cells express NKp30 and its ligands are expressed by trophoblast cells. Though these ligands have not yet been identified, this interaction has a potential to regulate fetal-maternal interface.^[18] The uNK cells dominantly express the inhibitory NKp30c isoform.^[19]

Further reading

• Djeu JY, Jiang K, Wei S . A view to a kill: signals triggering cytotoxicity . Clinical Cancer Research . 8 . 3 . 636–40 . March 2002 . 11895890 .
• Holzinger I, de Baey A, Messer G, Kick G, Zwierzina H, Weiss EH . Cloning and genomic characterization of LST1: a new gene in the human TNF region . Immunogenetics . 42 . 5 . 315–22 . 1995 . 7590964 . 10.1007/BF00179392 . 19916860 .
• de Baey A, Fellerhoff B, Maier S, Martinozzi S, Weidle U, Weiss EH . Complex expression pattern of the TNF region gene LST1 through differential regulation, initiation, and alternative splicing . Genomics . 45 . 3 . 591–600 . November 1997 . 9367684 . 10.1006/geno.1997.4963 .
• Neville MJ, Campbell RD . A new member of the Ig superfamily and a V-ATPase G subunit are among the predicted products of novel genes close to the TNF locus in the human MHC . Journal of Immunology . 162 . 8 . 4745–54 . April 1999 . 10.4049/jimmunol.162.8.4745 . 10202016 . 46517924 . free .
• Pende D, Parolini S, Pessino A, Sivori S, Augugliaro R, Morelli L, Marcenaro E, Accame L, Malaspina A, Biassoni R, Bottino C, Moretta L, Moretta A . 6 . Identification and molecular characterization of NKp30, a novel triggering receptor involved in natural cytotoxicity mediated by human natural killer cells . The Journal of Experimental Medicine . 190 . 10 . 1505–16 . November 1999 . 10562324 . 2195691 . 10.1084/jem.190.10.1505 .
• Sivakamasundari R, Raghunathan A, Zhang CY, Chowdhury RR, Weissman SM . Expression and cellular localization of the protein encoded by the 1C7 gene: a recently described component of the MHC . Immunogenetics . 51 . 8–9 . 723–32 . July 2000 . 10941844 . 10.1007/s002510000192 . 27714493 .
• Le Bouteiller P, Barakonyi A, Giustiniani J, Lenfant F, Marie-Cardine A, Aguerre-Girr M, Rabot M, Hilgert I, Mami-Chouaib F, Tabiasco J, Boumsell L, Bensussan A . 6 . Engagement of CD160 receptor by HLA-C is a triggering mechanism used by circulating natural killer (NK) cells to mediate cytotoxicity . Proceedings of the National Academy of Sciences of the United States of America . 99 . 26 . 16963–8 . December 2002 . 12486241 . 139252 . 10.1073/pnas.012681099 . 2002PNAS...9916963L . free .
• Augugliaro R, Parolini S, Castriconi R, Marcenaro E, Cantoni C, Nanni M, Moretta L, Moretta A, Bottino C . 6 . Selective cross-talk among natural cytotoxicity receptors in human natural killer cells . European Journal of Immunology . 33 . 5 . 1235–41 . May 2003 . 12731048 . 10.1002/eji.200323896 . 10724743 . free .
• Marcenaro E, Augugliaro R, Falco M, Castriconi R, Parolini S, Sivori S, Romeo E, Millo R, Moretta L, Bottino C, Moretta A . 6 . CD59 is physically and functionally associated with natural cytotoxicity receptors and activates human NK cell-mediated cytotoxicity . European Journal of Immunology . 33 . 12 . 3367–76 . December 2003 . 14635045 . 10.1002/eji.200324425 . 40345630 . free .
• Xie T, Rowen L, Aguado B, Ahearn ME, Madan A, Qin S, Campbell RD, Hood L . 6 . Analysis of the gene-dense major histocompatibility complex class III region and its comparison to mouse . Genome Research . 13 . 12 . 2621–36 . December 2003 . 14656967 . 403804 . 10.1101/gr.1736803 .
• Nowbakht P, Ionescu MC, Rohner A, Kalberer CP, Rossy E, Mori L, Cosman D, De Libero G, Wodnar-Filipowicz A . 6 . Ligands for natural killer cell-activating receptors are expressed upon the maturation of normal myelomonocytic cells but at low levels in acute myeloid leukemias . Blood . 105 . 9 . 3615–22 . May 2005 . 15657183 . 10.1182/blood-2004-07-2585 . free .
• Poggi A, Massaro AM, Negrini S, Contini P, Zocchi MR . Tumor-induced apoptosis of human IL-2-activated NK cells: role of natural cytotoxicity receptors . Journal of Immunology . 174 . 5 . 2653–60 . March 2005 . 15728472 . 10.4049/jimmunol.174.5.2653 . free .
• Vitale M, Della Chiesa M, Carlomagno S, Pende D, Aricò M, Moretta L, Moretta A . NK-dependent DC maturation is mediated by TNFalpha and IFNgamma released upon engagement of the NKp30 triggering receptor . Blood . 106 . 2 . 566–71 . July 2005 . 15784725 . 10.1182/blood-2004-10-4035 . free .
• Warren HS, Jones AL, Freeman C, Bettadapura J, Parish CR . Evidence that the cellular ligand for the human NK cell activation receptor NKp30 is not a heparan sulfate glycosaminoglycan . Journal of Immunology . 175 . 1 . 207–12 . July 2005 . 15972650 . 10.4049/jimmunol.175.1.207 . free .
• Joyce MG, Tran P, Zhuravleva MA, Jaw J, Colonna M, Sun PD . Crystal structure of human natural cytotoxicity receptor NKp30 and identification of its ligand binding site . Proceedings of the National Academy of Sciences of the United States of America . 108 . 15 . 6223–8 . April 2011 . 21444796 . 3076882 . 10.1073/pnas.1100622108 . 2011PNAS..108.6223J . free .

External links

• • PDBe-KB provides an overview of all the structure information available in the PDB for Human Natural cytotoxicity triggering receptor 3 (NCR3)

Notes and References

1. Nalabolu SR, Shukla H, Nallur G, Parimoo S, Weissman SM . Genes in a 220-kb region spanning the TNF cluster in human MHC . Genomics . 31 . 2 . 215–22 . January 1996 . 8824804 . 10.1006/geno.1996.0034 . free .
2. Sato M, Ohashi J, Tsuchiya N, Tadokoro K, Juji T, Hanaoka K, Tokunaga K, Yabe T . 6 . Identification of novel single nucleotide substitutions in the NKp30 gene expressed in human natural killer cells . Tissue Antigens . 58 . 4 . 255–8 . October 2001 . 11782277 . 10.1034/j.1399-0039.2001.580406.x .
3. Web site: Entrez Gene: NCR3 natural cytotoxicity triggering receptor 3.
4. Barrow AD, Martin CJ, Colonna M . The Natural Cytotoxicity Receptors in Health and Disease . Frontiers in Immunology . 10 . 909 . 2019-05-07 . 31134055 . 6514059 . 10.3389/fimmu.2019.00909 . free .
5. Pende D, Parolini S, Pessino A, Sivori S, Augugliaro R, Morelli L, Marcenaro E, Accame L, Malaspina A, Biassoni R, Bottino C, Moretta L, Moretta A . 6 . Identification and molecular characterization of NKp30, a novel triggering receptor involved in natural cytotoxicity mediated by human natural killer cells . The Journal of Experimental Medicine . 190 . 10 . 1505–16 . November 1999 . 10562324 . 2195691 . 10.1084/jem.190.10.1505 .
6. Kruse PH, Matta J, Ugolini S, Vivier E . Natural cytotoxicity receptors and their ligands . Immunology and Cell Biology . 92 . 3 . 221–9 . March 2014 . 24366519 . 10.1038/icb.2013.98 . 38667462 .
7. Pinheiro PF, Justino GC, Marques MM . NKp30 - A prospective target for new cancer immunotherapy strategies . British Journal of Pharmacology . 177 . 20 . 4563–4580 . October 2020 . 32737988 . 7520444 . 10.1111/bph.15222 .
8. Pazina T, Shemesh A, Brusilovsky M, Porgador A, Campbell KS . Regulation of the Functions of Natural Cytotoxicity Receptors by Interactions with Diverse Ligands and Alterations in Splice Variant Expression . Frontiers in Immunology . 8 . 369 . 2017-03-30 . 28424697 . 5371597 . 10.3389/fimmu.2017.00369 . free .
9. Kaifu T, Escalière B, Gastinel LN, Vivier E, Baratin M . B7-H6/NKp30 interaction: a mechanism of alerting NK cells against tumors . Cellular and Molecular Life Sciences . 68 . 21 . 3531–9 . November 2011 . 21877119 . 10.1007/s00018-011-0802-7 . 22483622 . 11114815 .
10. Delahaye NF, Rusakiewicz S, Martins I, Ménard C, Roux S, Lyonnet L, Paul P, Sarabi M, Chaput N, Semeraro M, Minard-Colin V, Poirier-Colame V, Chaba K, Flament C, Baud V, Authier H, Kerdine-Römer S, Pallardy M, Cremer I, Peaudecerf L, Rocha B, Valteau-Couanet D, Gutierrez JC, Nunès JA, Commo F, Bonvalot S, Ibrahim N, Terrier P, Opolon P, Bottino C, Moretta A, Tavernier J, Rihet P, Coindre JM, Blay JY, Isambert N, Emile JF, Vivier E, Lecesne A, Kroemer G, Zitvogel L . 6 . Alternatively spliced NKp30 isoforms affect the prognosis of gastrointestinal stromal tumors . Nature Medicine . 17 . 6 . 700–7 . June 2011 . 21552268 . 10.1038/nm.2366 . 22671469 .
11. Correia MP, Stojanovic A, Bauer K, Juraeva D, Tykocinski LO, Lorenz HM, Brors B, Cerwenka A . 6 . Distinct human circulating NKp30⁺FcεRIγ⁺CD8⁺ T cell population exhibiting high natural killer-like antitumor potential . Proceedings of the National Academy of Sciences of the United States of America . 115 . 26 . E5980–E5989 . June 2018 . 29895693 . 6042091 . 10.1073/pnas.1720564115 . 2018PNAS..115E5980C . free .
12. Correia DV, Fogli M, Hudspeth K, da Silva MG, Mavilio D, Silva-Santos B . Differentiation of human peripheral blood Vδ1+ T cells expressing the natural cytotoxicity receptor NKp30 for recognition of lymphoid leukemia cells . Blood . 118 . 4 . 992–1001 . July 2011 . 21633088 . 10.1182/blood-2011-02-339135 . 2434/223196 . free .
13. Porgador A . Natural cytotoxicity receptors: pattern recognition and involvement of carbohydrates . TheScientificWorldJournal . 5 . 151–4 . February 2005 . 15759080 . 5936559 . 10.1100/tsw.2005.22 . free .
14. Moretta A, Bottino C, Vitale M, Pende D, Cantoni C, Mingari MC, Biassoni R, Moretta L . 6 . Activating receptors and coreceptors involved in human natural killer cell-mediated cytolysis . Annual Review of Immunology . 19 . 1 . 197–223 . April 2001 . 11244035 . 10.1146/annurev.immunol.19.1.197 .
15. Seidel E, Glasner A, Mandelboim O . Virus-mediated inhibition of natural cytotoxicity receptor recognition . Cellular and Molecular Life Sciences . 69 . 23 . 3911–20 . December 2012 . 22547090 . 10.1007/s00018-012-1001-x . 16482529 . 11115132 .
16. Sojka DK, Yang L, Yokoyama WM . Uterine Natural Killer Cells . Frontiers in Immunology . 10 . 960 . 2019-05-01 . 31118936 . 6504766 . 10.3389/fimmu.2019.00960 . free .
17. Moffett A, Colucci F . Uterine NK cells: active regulators at the maternal-fetal interface . The Journal of Clinical Investigation . 124 . 5 . 1872–9 . May 2014 . 24789879 . 4001528 . 10.1172/JCI68107 .
18. Hanna J, Goldman-Wohl D, Hamani Y, Avraham I, Greenfield C, Natanson-Yaron S, Prus D, Cohen-Daniel L, Arnon TI, Manaster I, Gazit R, Yutkin V, Benharroch D, Porgador A, Keshet E, Yagel S, Mandelboim O . 6 . Decidual NK cells regulate key developmental processes at the human fetal-maternal interface . Nature Medicine . 12 . 9 . 1065–74 . September 2006 . 16892062 . 10.1038/nm1452 . 19158471 .
19. Siewiera J, Gouilly J, Hocine HR, Cartron G, Levy C, Al-Daccak R, Jabrane-Ferrat N . Natural cytotoxicity receptor splice variants orchestrate the distinct functions of human natural killer cell subtypes . Nature Communications . 6 . 1 . 10183 . December 2015 . 26666685 . 4682172 . 10.1038/ncomms10183 . 2015NatCo...610183S .