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Structural highlights

Disease

[ZAP70_HUMAN] Defects in ZAP70 are the cause of selective T-cell defect (STCD) [MIM:269840]. A form of severe combined immunodeficiency characterized by a selective absence of CD8+ T cells.^{[1] [2] [3] [4] [5]}

Function

[ZAP70_HUMAN] Tyrosine kinase that plays an essential role in regulation of the adaptive immune response. Regulates motility, adhesion and cytokine expression of mature T-cells, as well as thymocyte development. Contributes also to the development and activation of primary B-lymphocytes. When antigen presenting cells (APC) activate T-cell receptor (TCR), a serie of phosphorylations lead to the recruitment of ZAP70 to the doubly phosphorylated TCR component CD247/CD3Z through ITAM motif at the plasma membrane. This recruitment serves to localization to the stimulated TCR and to relieve its autoinhibited conformation. Release of ZAP70 active conformation is further stabilized by phosphorylation mediated by LCK. Subsequently, ZAP70 phosphorylates at least 2 essential adapter proteins: LAT and LCP2. In turn, a large number of signaling molecules are recruited and ultimately lead to lymphokine production, T-cell proliferation and differentiation. Furthermore, ZAP70 controls cytoskeleton modifications, adhesion and mobility of T-lymphocytes, thus ensuring correct delivery of effectors to the APC. ZAP70 is also required for TCR-CD247/CD3Z internalization and degradation through interaction with the E3 ubiquitin-protein ligase CBL and adapter proteins SLA and SLA2. Thus, ZAP70 regulates both T-cell activation switch on and switch off by modulating TCR expression at the T-cell surface. During thymocyte development, ZAP70 promotes survival and cell-cycle progression of developing thymocytes before positive selection (when cells are still CD4/CD8 double negative). Additionally, ZAP70-dependent signaling pathway may also contribute to primary B-cells formation and activation through B-cell receptor (BCR).^{[6] [7] [8] [9] [10]}

References

1. ↑ Arpaia E, Shahar M, Dadi H, Cohen A, Roifman CM. Defective T cell receptor signaling and CD8+ thymic selection in humans lacking zap-70 kinase. Cell. 1994 Mar 11;76(5):947-58. PMID:8124727
2. ↑ Chan AC, Kadlecek TA, Elder ME, Filipovich AH, Kuo WL, Iwashima M, Parslow TG, Weiss A. ZAP-70 deficiency in an autosomal recessive form of severe combined immunodeficiency. Science. 1994 Jun 10;264(5165):1599-601. PMID:8202713
3. ↑ Toyabe S, Watanabe A, Harada W, Karasawa T, Uchiyama M. Specific immunoglobulin E responses in ZAP-70-deficient patients are mediated by Syk-dependent T-cell receptor signalling. Immunology. 2001 Jun;103(2):164-71. PMID:11412303
4. ↑ Elder ME, Skoda-Smith S, Kadlecek TA, Wang F, Wu J, Weiss A. Distinct T cell developmental consequences in humans and mice expressing identical mutations in the DLAARN motif of ZAP-70. J Immunol. 2001 Jan 1;166(1):656-61. PMID:11123350
5. ↑ Turul T, Tezcan I, Artac H, de Bruin-Versteeg S, Barendregt BH, Reisli I, Sanal O, van Dongen JJ, van der Burg M. Clinical heterogeneity can hamper the diagnosis of patients with ZAP70 deficiency. Eur J Pediatr. 2009 Jan;168(1):87-93. doi: 10.1007/s00431-008-0718-x. Epub 2008, May 29. PMID:18509675 doi:10.1007/s00431-008-0718-x
6. ↑ Chan AC, Iwashima M, Turck CW, Weiss A. ZAP-70: a 70 kd protein-tyrosine kinase that associates with the TCR zeta chain. Cell. 1992 Nov 13;71(4):649-62. PMID:1423621
7. ↑ Arpaia E, Shahar M, Dadi H, Cohen A, Roifman CM. Defective T cell receptor signaling and CD8+ thymic selection in humans lacking zap-70 kinase. Cell. 1994 Mar 11;76(5):947-58. PMID:8124727
8. ↑ Bubeck Wardenburg J, Fu C, Jackman JK, Flotow H, Wilkinson SE, Williams DH, Johnson R, Kong G, Chan AC, Findell PR. Phosphorylation of SLP-76 by the ZAP-70 protein-tyrosine kinase is required for T-cell receptor function. J Biol Chem. 1996 Aug 16;271(33):19641-4. PMID:8702662
9. ↑ Zhang W, Sloan-Lancaster J, Kitchen J, Trible RP, Samelson LE. LAT: the ZAP-70 tyrosine kinase substrate that links T cell receptor to cellular activation. Cell. 1998 Jan 9;92(1):83-92. PMID:9489702
10. ↑ Wang HY, Altman Y, Fang D, Elly C, Dai Y, Shao Y, Liu YC. Cbl promotes ubiquitination of the T cell receptor zeta through an adaptor function of Zap-70. J Biol Chem. 2001 Jul 13;276(28):26004-11. Epub 2001 May 15. PMID:11353765 doi:10.1074/jbc.M010738200
11. ↑ Visperas PR, Winger JA, Horton TM, Shah NH, Aum DJ, Tao A, Barros T, Yan Q, Wilson CG, Arkin MR, Weiss A, Kuriyan J. Modification by covalent reaction or oxidation of cysteine residues in the tandem-SH2 domains of ZAP-70 and Syk can block phosphopeptide binding. Biochem J. 2015 Jan 1;465(1):149-61. doi: 10.1042/BJ20140793. PMID:25287889 doi:http://dx.doi.org/10.1042/BJ20140793