Scientists Identify Key Protein Interaction Controlling Immune Response and Autoimmune Disease
Researchers have discovered a direct physical interaction between two proteins, SLC15A4 and LAMTOR1, that is required for endolysosomal immune receptors to activate the mTOR signaling pathway and drive inflammatory cytokine production. SLC15A4 is a known genetic risk factor for systemic lupus erythematosus (SLE), and its role in coordinating innate immune signaling had not been fully understood. The findings reveal a previously uncharacterized molecular interface that could serve as a therapeutic target for autoimmune diseases like SLE.
A new preprint study posted to bioRxiv identifies a direct interaction between the endolysosomal transporter SLC15A4 and LAMTOR1, a scaffold subunit of the lysosomal Ragulator complex, as a critical step linking Toll-like receptors (TLRs) 7, 8, and 9 to mTORC1 activation and downstream inflammatory signaling. These endolysosomal TLRs are important for detecting microbial nucleic acids, but their overactivation is associated with autoimmune pathology, particularly in systemic lupus erythematosus. Using structural modeling and site-directed mutagenesis, the researchers found that an alpha-helix of LAMTOR1 engages the substrate-binding pocket of SLC15A4, and disrupting this interface broadly suppresses TLR7-9-mediated cytokine production. The interaction was also found to regulate IRF5/7 transcription factor signaling and downstream gene expression through stimulus-dependent mechanisms. SLC15A4 has been genetically linked to SLE susceptibility, and these findings provide a mechanistic explanation for how it contributes to inflammatory responses. The study defines a novel SLC15A4-LAMTOR1 signaling axis that couples endolysosomal TLR activation to mTOR and cytokine output, offering a potential new avenue for therapeutic intervention in lupus and related autoimmune conditions.
What's missing
As a preprint, this study has not yet undergone peer review, so its findings should be interpreted with caution. The study does not report in vivo validation in animal models of SLE or human patient data, leaving open the question of whether disrupting the SLC15A4-LAMTOR1 interface would be therapeutically effective or safe in a disease context.
What different sources said
- bioRxivCenter
The SLC15A4-LAMTOR1 interaction licenses endolysosomal TLR-mediated mTOR signaling and inflammatory cytokine production
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