SLP-76 Sterile alpha Motif (SAM) and Individual H5 alpha Helix Mediate Oligomer Formation for Microclusters and T-cell Activation

Liu, HB;Thaker, YR;Stagg, L;Schneider, H;Ladbury, JE;Rudd, CE

[Liu, Hebin; Thaker, Youg Raj; Schneider, Helga; Rudd, Christopher E.] Univ Cambridge, Cell Signalling Sect, Dept Pathol, Cambridge CB2 1QP, England.
[Liu, Hebin] Xian Jiaotong Liverpool Univ, Dept Biol Sci, Suzhou Ind Pk 215123, Jiangsu, Peoples R China.
[Stagg, Loren; Ladbury, John E.] Univ Texas MD Anderson Canc Ctr, Dept Biochem & Mol Biol, Houston, TX 77030 USA.

JOURNAL OF BIOLOGICAL CHEMISTRY

Volume:288 Issue:41Pages:29539-29549

DOI:10.1074/jbc.M112.424846

Publication Year:2013

JCR:Q1

CAS JCR:2区

ESI Discipline:BIOLOGY & BIOCHEMISTRY

Latest Impact Factor:5.157

Document Type:Journal Article

Identifier:http://hdl.handle.net/20.500.12791/001619

Abstract

Despite the importance of the immune adaptor SLP-76 in T-cell immunity, it has been unclear whether SLP-76 directly self-associates to form higher order oligomers for T-cell activation. In this study, we show that SLP-76 self-associates in response to T-cell receptor ligation as mediated by the N-terminal sterile alpha motif (SAM) domain. SLP-76 co-precipitated alternately tagged SLP-76 in response to anti-CD3 ligation. Dynamic light scattering and fluorescent microscale thermophoresis of the isolated SAM domain (residues 1-78) revealed evidence of dimers and tetramers. Consistently, deletion of the SAM region eliminated SLP-76 co-precipitation of itself, concurrent with a loss of microcluster formation, nuclear factor of activated T-cells (NFAT) transcription, and interleukin-2 production in Jurkat or primary T-cells. Furthermore, the H5 alpha helix within the SAM domain contributed to self-association. Retention of H5 in the absence of H1-4 sufficed to support SLP-76 self-association with smaller microclusters that nevertheless enhancedanti-CD3-drivenAP1/NFAT transcription and IL-2 production. By contrast, deletion of the H5 alpha helix impaired self-association and anti-CD3 induced AP1/NFAT transcription. Our data identified for the first time a role for the SAM domain in mediating SLP-76 self-association for T-cell function.

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