Staphylococcal Superantigens Use LAMA2 as a Coreceptor GPCT signaling To Activate T Cells
February 05, 2018
Zhigang Li, Joseph J. Zeppa, Mark A. Hancock, John K. McCormick, Terence M. Doherty, Geoffrey N. Hendy and Joaquín Madrenas J Immunol January 15, 2018, ji1701212; DOI: https://doi.org/10.4049/jimmunol.1701212 (Published online February 5, 2018) This work was supported by the Canadian Institutes for Health Research. J.M. holds a tier I Canada Research Chair in Human Immunology. The Department of Microbiology and Immunology Flow Cytometry and Cell Sorting Facility and McGill Surface Plasmon Resonance–Mass Spectrometry Facility are supported by the Canada Foundation for Innovation.
Canonical Ag-dependent TCR signaling relies on activation of the src-family tyrosine kinase LCK. However, staphylococcal superantigens can trigger TCR signaling by activating an alternative pathway that is independent of LCK and utilizes a Gα11-containing G protein–coupled receptor (GPCR) leading to PLCβ activation. The molecules linking the superantigen to GPCR signaling are unknown. Using the ligand-receptor capture technology LRC-TriCEPS, we identified LAMA2, the α2 subunit of the extracellular matrix protein laminin, as the coreceptor for staphylococcal superantigens. Complementary binding assays (ELISA, pull-downs, and surface plasmon resonance) provided direct evidence of the interaction between staphylococcal enterotoxin E and LAMA2. Through its G4 domain, LAMA2 mediated the LCK-independent T cell activation by these toxins. Such a coreceptor role of LAMA2 involved a GPCR of the calcium-sensing receptor type because the selective antagonist NPS 2143 inhibited superantigen-induced T cell activation in vitro and delayed the effects of toxic shock syndrome in vivo. Collectively, our data identify LAMA2 as a target of antagonists of staphylococcal superantigens to treat toxic shock syndrome.
Zhigang Li, Joseph J. Zeppa, Mark A. Hancock, John K. McCormick, Terence M. Doherty, Geoffrey N. Hendy and Joaquín Madrenas