G307S DNAM-1 mutation exacerbates autoimmune encephalomyelitis via enhancing CD4+ T cell activation

Abstract

Although rs763361, which causes a non-synonymous glycine-to-serine mutation at residue 307 (G307S mutation) of the DNAM-1 immunoreceptor, is a single-nucleotide polymorphism (SNP) associated with autoimmune disease susceptibility, little is known about how the SNP is involved in pathogenesis. Here, we established CD4+ T cells expressing wild-type or G307S DNAM-1 and showed that the costimulatory signal from G307S DNAM-1 induced greater pro-inflammatory cytokine production and cell proliferation than that from wild-type DNAM-1. The G307S mutation also enhanced the recruitment of the tyrosine kinase Lck and augmented tyrosine phosphorylation at residue 322 (Tyr322) of DNAM-1. However, conversion of Tyr322 of DNAM-1 to phenylalanine (Y322F mutation) canceled the enhanced activation of CD4+ T cell transfectants expressing G307S DNAM-1. Adoptive transfer of myelin-antigen-specific CD4+ T cells expressing G307S DNAM-1 into mice exacerbated experimental autoimmune encephalomyelitis compared with the transfer of cells expressing wild-type DNAM-1. These findings suggest that rs763361 is a gain-of-function mutation that enhances DNAM-1-mediated costimulatory signaling for proinflammatory responses.