Abstract
Signaling lymphocytic activation molecule (SLAM)-associated protein (SAP) is a Src homology (SH) domain 2-containing intracellular adaptor protein that is predominantly expressed in the hematopoietic system by T lymphocytes and NK cells. SAP protein is encoded by the SH2D1A gene located on the X chromosome. Loss-of-function mutations in SAP cause the X-linked lymphoproliferative disease (XLP), a severe immunodeficiency characterized by heightened susceptibility to Epstein-Barr virus and impaired humoral immunity. Normal individuals express several functional and non-functional isoforms of SAP as a result of alternative splicing. In this study, we identify a cryptic exon in the murine Sh2d1a gene. At the mRNA level, the new isoform of SAP (SAP-2) that includes this new exon is widely expressed in lymphoid tissues by C57BL/6 and 129 strains of inbred mice. SAP-2 accounts for approximately 1%–3% of total SAP transcripts, and it is dynamically regulated during lymphocyte activation. At the protein level, the SAP-2 isoform is a 144 amino-acid protein. Compared to the dominant 126 aminoacid SAP-1 isoform, the additional 18 amino acids are inserted into a structural region that is critical for phosphotyrosine binding. Our functional analysis in vitro indicates that SAP-2 is a non-functional isoform due to decreased protein stability. Thus, both human and mouse have multiple SAP splice isoforms that may or may not function. Modulation of relative proportions of these isoforms is potentially a mechanism whereby cells can regulate SAP-mediated biological activities.
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References
Purtilo DT, Cassel CK, Yang JP, Harper R. X-linked recessive progressive combined variable immunodeficiency (duncan’s disease). Lancet, 1975, 1: 935–940
Engel P, Eck MJ, Terhorst C. The SAP and SLAM families in immune responses and X-linked lymphoproliferative disease. Nat Rev Immunol, 2003, 3: 813–821
Grierson HL, Skare J, Hawk J, Pauza M, Purtilo DT. Immunoglobulin class and subclass deficiencies prior to Epstein-Barr virus infection in males with X-linked lymphoproliferative disease. Am J Med Genet, 1991, 40: 294–297
Skare JC, Sullivan JL, Milunsky A. Mapping the mutation causing the X-linked lymphoproliferative syndrome in relation to restriction fragment length polymorphisms on Xq. Hum Genet, 1989, 82: 349–353
Skare JC, Milunsky A, Byron KS, Sullivan JL. Mapping the X-linked lymphoproliferative syndrome. Proc Natl Acad Sci USA, 1987, 84: 2015–2018
Nichols KE, Harkin DP, Levitz S, Krainer M, Kolquist KA, Genovese C, Bernard A, Ferguson M, Zuo L, Snyder E, Buckler AJ, Wise C, Ashley J, Lovett M, Valentine MB, Look AT, Gerald W, Housman DE, Haber DA. Inactivating mutations in an SH2 domain-encoding gene in X-linked lymphoproliferative syndrome. Proc Natl Acad Sci USA, 1998, 95: 13765–13770
Sayos J, Wu C, Morra M, Wang N, Zhang X, Allen D, van Schaik S, Notarangelo L, Geha R, Roncarolo MG, Oettgen H, De Vries JE, Aversa G, Terhorst C. The X-linked lymphoproliferative-disease gene product SAP regulates signals induced through the co-receptor SLAM. Nature, 1998, 395: 462–469
Cannons JL, Tangye SG, Schwartzberg PL. SLAM family receptors and SAP adaptors in immunity. Annu Rev Immunol, 2010, 29: 665–705
Crotty S, Kersh EN, Cannons J, Schwartzberg PL, Ahmed R. SAP is required for generating long-term humoral immunity. Nature, 2003, 421: 282–287
Qi H, Cannons JL, Klauschen F, Schwartzberg PL, Germain RN. SAP-controlled T-B cell interactions underlie germinal centre formation. Nature, 2008, 455: 764–769
Kageyama R, Cannons JL, Zhao F, Yusuf I, Lao C, Locci M, Schwartzberg PL, Crotty S. The receptor LY108 functions as a SAP adaptor-dependent on-off switch for T cell help to B cells and NKT cell development. Immunity, 2012, 36: 986–1002
Zhao F, Cannons JL, Dutta M, Griffiths GM, Schwartzberg PL. Positive and negative signaling through SLAM receptors regulate synapse organization and thresholds of cytolysis. Immunity, 2012, 36: 1003–1016
Coffey AJ, Brooksbank RA, Brandau O, Oohashi T, Howell GR, Bye JM, Cahn AP, Durham J, Heath P, Wray P, Pavitt R, Wilkinson J, Leversha M, Huckle E, Shaw-Smith CJ, Dunham A, Rhodes S, Schuster V, Porta G, Yin L, Serafini P, Sylla B, Zollo M, Franco B, Bolino A, Seri M, Lanyi A, Davis JR, Webster D, Harris A, Lenoir G, de St Basile G, Jones A, Behloradsky BH, Achatz H, Murken J, Fassler R, Sumegi J, Romeo G, Vaudin M, Ross MT, Meindl A, Bentley DR. Host response to EBV infection in X-linked lymphoproliferative disease results from mutations in an SH2-domain encoding gene. Nat Genet, 1998, 20: 129–135
Czar MJ, Kersh EN, Mijares LA, Oohashi T, Howell GR, Bye JM, Cahn AP, Durham J, Heath P, Wray P, Pavitt R, Wilkinson J, Leversha M, Huckle E, Shaw-Smith CJ, Dunham A, Rhodes S, Schuster V, Porta G, Yin L, Serafini P, Sylla B, Zollo M, Franco B, Bolino A, Seri M, Lanyi A, Davis JR, Webster D, Harris A, Lenoir G, de St Basile G, Jones A, Behloradsky BH, Achatz H, Murken J, Fassler R, Sumegi J, Romeo G, Vaudin M, Ross MT, Meindl A, Bentley DR. Altered lymphocyte responses and cytokine production in mice deficient in the X-linked lymphoproliferative disease gene SH2D1A/DSHP/SAP. Proc Natl Acad Sci USA, 2001, 98: 7449–7454
Livak KJ, Schmittgen TD. Analysis of relative gene expression data using real-time quantitative PCR and the 2−ΔΔCT method. Methods, 2001, 25: 402–408
Xu H, Li X, Liu D, Li J, Zhang X, Chen X, Hou S, Peng L, Xu C, Liu W, Zhang L, Qi H. Follicular T-helper cell recruitment governed by bystander B cells and ICOS-driven motility. Nature, 2013, 496: 523–527
Veillette A, Zhang S, Shi X, Dong Z, Davidson D, Zhong MC. SAP expression in T cells, not in B cells, is required for humoral immunity. Proc Natl Acad Sci USA, 2008, 105: 1273–1278
Pandya-Jones A. Pre-mRNA splicing during transcription in the mammalian system. Wiley Interdiscip Rev RNA, 2011, 2: 700–717
Wu C, Nguyen KB, Pien GC, Wang N, Gullo C, Howie D, Sosa MR, Edwards MJ, Borrow P, Satoskar AR, Sharpe AH, Biron CA, Terhorst C. SAP controls T cell responses to virus and terminal differentiation of TH2 cells. Nat Immunol, 2001, 2: 410–414
Wu C, Sayos J, Wang N, Howie D, Coyle A, Terhorst C. Genomic organization and characterization of mouse SAP, the gene that is altered in X-linked lymphoproliferative disease. Immunogenetics, 2000, 51: 805–815
Latour S, Gish G, Helgason CD, Humphries RK, Pawson T, Veillette A. Regulation of SLAM-mediated signal transduction by SAP, the X-linked lymphoproliferative gene product. Nat Immunol, 2001, 2: 681–690
Poy F, Yaffe MB, Sayos J, Saxena K, Morra M, Sumegi J, Cantley LC, Terhorst C, Eck MJ. Crystal structures of the XLP protein SAP reveal a class of SH2 domains with extended, phosphotyrosine-independent sequence recognition. Mol Cell, 1999, 4: 555–561
Morra M, Lu J, Poy F, Martin M, Sayos J, Calpe S, Gullo C, Howie D, Rietdijk S, Thompson A, Coyle AJ, Denny C, Yaffe MB, Engel P, Eck MJ, Terhorst C. Structural basis for the interaction of the free SH2 domain EAT-2 with SLAM receptors in hematopoietic cells. EMBO J, 2001, 20: 5840–5852
de Almeida SF, Carmo-Fonseca M. Design principles of interconnections between chromatin and pre-mRNA splicing. Trends Biochem Sci, 2012, 37: 248–253
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Wu, L., Lu, P., Ma, W. et al. Identification of a new isoform of the murine Sh2d1a gene and its functional implications. Sci. China Life Sci. 57, 81–87 (2014). https://doi.org/10.1007/s11427-013-4584-z
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DOI: https://doi.org/10.1007/s11427-013-4584-z