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Gene Review

SIGLEC7  -  sialic acid binding Ig-like lectin 7

Homo sapiens

Synonyms: AIRM-1, AIRM1, Adhesion inhibitory receptor molecule 1, CD328, CDw328, ...
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Disease relevance of SIGLEC7


High impact information on SIGLEC7

  • Similar to other sialoadhesin molecules, p75/AIRM1 appears to mediate sialic acid-dependent ligand recognition [5].
  • The p75/AIRM1 gene is located on human chromosome 19 and encodes a novel member of the sialoadhesin family characterized by three immunoglobulin-like extracellular domains (one NH(2)-terminal V-type and two C2-type) and a classical immunoreceptor tyrosine-based inhibitory motif (ITIM) in the cytoplasmic portion [5].
  • In lymphoid cells, p75/AIRM1 is confined to natural killer cells and mediates inhibition of their cytolytic activity [1].
  • P75/AIRM1 is a recently identified surface molecule that belongs to the sialoadhesin family and displays homology with the myeloid cell antigen CD33 [1].
  • In vitro proliferation and differentiation of cord blood-derived CD34(+) cells (induced by stem cell factor and granulocyte-macrophage colony-stimulating factor) were consistently inhibited by the addition of anti-p75/AIRM1 mAb [1].

Biological context of SIGLEC7


Anatomical context of SIGLEC7


Associations of SIGLEC7 with chemical compounds

  • Siglec-7 is predicted to contain three extracellular immunoglobulin-like domains that comprise an N-terminal V-set domain and two C2-set domains, a transmembrane region and a cytoplasmic tail containing two tyrosine residues embodied in immunoreceptor tyrosine-based inhibition motif-like motifs [6].
  • This characteristic clearly distinguishes p75 from Sos since Sos is not a phosphotyrosine protein [10].
  • Binding assays showed that, similar to Siglec-7, Siglec-9 recognized sialic acid in either the alpha2,3- or alpha2, 6-glycosidic linkage to galactose [11].
  • Probing the cis interactions of the inhibitory receptor Siglec-7 with {alpha}2,8-disialylated ligands on natural killer cells and other leukocytes using glycan-specific antibodies and by analysis of {alpha}2,8-sialyltransferase gene expression [12].
  • Similar to hSiglec-7, mSiglec-E preferred alpha 2-8-linked disialic acid over alpha 2-3- and alpha 2-6-linked sialic acids [13].

Regulatory relationships of SIGLEC7


Other interactions of SIGLEC7

  • A double mutant (P439S, N458T) or triple mutant (I435L, P439S, N458T) recruited SHPs as much as did Siglec-9, indicating that Pro439 in the proximal motif and Asn458 in the distal motif of Siglec-7 attenuate its ability to recruit phosphatases [15].
  • Collectively, these data indicate that in T cells, two proteins can complex with the Grb2 SH3 domains: Sos and a p75 molecule that is tyrosine-phosphorylated in TCR-activated cells [10].
  • In view of its homology with p75/AIRM1, a recently identified surface molecule which exerts a potent inhibition on NK cell function, we re-evaluated the effect of CD33 engagement in defined myeloid cell functions [16].
  • To determine any differences in the glycan composition of siglec-5, siglec-7 and siglec-8 that may modify their function, we released and characterized the N-linked oligosaccharide distribution in these three glycoproteins [17].
  • The glycan pools from siglec-5 and siglec-7 contained a larger proportion of sialylated and core-fucosylated biantennary, triantennary and tetra-antennary oligosaccharides, whereas the carbohydrate mixture released from siglec-8 is noticeably less sialylated and is more abundant in 'high-mannose'-type glycans [17].

Analytical, diagnostic and therapeutic context of SIGLEC7


  1. Engagement of p75/AIRM1 or CD33 inhibits the proliferation of normal or leukemic myeloid cells. Vitale, C., Romagnani, C., Falco, M., Ponte, M., Vitale, M., Moretta, A., Bacigalupo, A., Moretta, L., Mingari, M.C. Proc. Natl. Acad. Sci. U.S.A. (1999) [Pubmed]
  2. p75/AIRM1 and CD33, two sialoadhesin receptors that regulate the proliferation or the survival of normal and leukemic myeloid cells. Mingari, M.C., Vitale, C., Romagnani, C., Falco, M., Moretta, L. Immunol. Rev. (2001) [Pubmed]
  3. Binding specificity of siglec7 to disialogangliosides of renal cell carcinoma: possible role of disialogangliosides in tumor progression. Ito, A., Handa, K., Withers, D.A., Satoh, M., Hakomori, S. FEBS Lett. (2001) [Pubmed]
  4. Loss of disialyl Lewis(a), the ligand for lymphocyte inhibitory receptor sialic acid-binding immunoglobulin-like lectin-7 (Siglec-7) associated with increased sialyl Lewis(a) expression on human colon cancers. Miyazaki, K., Ohmori, K., Izawa, M., Koike, T., Kumamoto, K., Furukawa, K., Ando, T., Kiso, M., Yamaji, T., Hashimoto, Y., Suzuki, A., Yoshida, A., Takeuchi, M., Kannagi, R. Cancer Res. (2004) [Pubmed]
  5. Identification and molecular cloning of p75/AIRM1, a novel member of the sialoadhesin family that functions as an inhibitory receptor in human natural killer cells. Falco, M., Biassoni, R., Bottino, C., Vitale, M., Sivori, S., Augugliaro, R., Moretta, L., Moretta, A. J. Exp. Med. (1999) [Pubmed]
  6. Identification and characterization of a novel siglec, siglec-7, expressed by human natural killer cells and monocytes. Nicoll, G., Ni, J., Liu, D., Klenerman, P., Munday, J., Dubock, S., Mattei, M.G., Crocker, P.R. J. Biol. Chem. (1999) [Pubmed]
  7. The membrane-proximal immunoreceptor tyrosine-based inhibitory motif is critical for the inhibitory signaling mediated by Siglecs-7 and -9, CD33-related Siglecs expressed on human monocytes and NK cells. Avril, T., Floyd, H., Lopez, F., Vivier, E., Crocker, P.R. J. Immunol. (2004) [Pubmed]
  8. Negative regulation of T cell receptor signaling by Siglec-7 (p70/AIRM) and Siglec-9. Ikehara, Y., Ikehara, S.K., Paulson, J.C. J. Biol. Chem. (2004) [Pubmed]
  9. Siglec-7: a sialic acid-binding lectin of the immunoglobulin superfamily. Angata, T., Varki, A. Glycobiology (2000) [Pubmed]
  10. SH3 domains of the adapter molecule Grb2 complex with two proteins in T cells: the guanine nucleotide exchange protein Sos and a 75-kDa protein that is a substrate for T cell antigen receptor-activated tyrosine kinases. Reif, K., Buday, L., Downward, J., Cantrell, D.A. J. Biol. Chem. (1994) [Pubmed]
  11. Siglec-9, a novel sialic acid binding member of the immunoglobulin superfamily expressed broadly on human blood leukocytes. Zhang, J.Q., Nicoll, G., Jones, C., Crocker, P.R. J. Biol. Chem. (2000) [Pubmed]
  12. Probing the cis interactions of the inhibitory receptor Siglec-7 with {alpha}2,8-disialylated ligands on natural killer cells and other leukocytes using glycan-specific antibodies and by analysis of {alpha}2,8-sialyltransferase gene expression. Avril, T., North, S.J., Haslam, S.M., Willison, H.J., Crocker, P.R. J. Leukoc. Biol. (2006) [Pubmed]
  13. The murine inhibitory receptor mSiglec-E is expressed broadly on cells of the innate immune system whereas mSiglec-F is restricted to eosinophils. Zhang, J.Q., Biedermann, B., Nitschke, L., Crocker, P.R. Eur. J. Immunol. (2004) [Pubmed]
  14. High resolution crystal structures of Siglec-7. Insights into ligand specificity in the Siglec family. Alphey, M.S., Attrill, H., Crocker, P.R., van Aalten, D.M. J. Biol. Chem. (2003) [Pubmed]
  15. Characterization of inhibitory signaling motifs of the natural killer cell receptor Siglec-7: attenuated recruitment of phosphatases by the receptor is attributed to two amino acids in the motifs. Yamaji, T., Mitsuki, M., Teranishi, T., Hashimoto, Y. Glycobiology (2005) [Pubmed]
  16. Engagement of CD33 surface molecules prevents the generation of dendritic cells from both monocytes and CD34+ myeloid precursors. Ferlazzo, G., Spaggiari, G.M., Semino, C., Melioli, G., Moretta, L. Eur. J. Immunol. (2000) [Pubmed]
  17. A comparative study of the asparagine-linked oligosaccharides on siglec-5, siglec-7 and siglec-8, expressed in a CHO cell line, and their contribution to ligand recognition. Freeman, S., Birrell, H.C., D'Alessio, K., Erickson-Miller, C., Kikly, K., Camilleri, P. Eur. J. Biochem. (2001) [Pubmed]
  18. Expression, crystallization and preliminary crystallographic analysis of the extracellular IgV-like domain of the human natural killer cell inhibitory receptor p75/AIRM1. Dimasi, N., Moretta, L., Biassoni, R., Mariuzza, R.A. Acta Crystallogr. D Biol. Crystallogr. (2003) [Pubmed]
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