Cell-Surface RNA Forms Ternary Complex with RNA-Binding Protein and Heparan Sulfate to Recruit Immune Receptors Complex with RNA-Binding Protein and Heparan Sulfate to Recruit Immune Receptor

ABSTRACT: Recent discoveries have shown the presence of RNA molecules on the cell surface, defying the traditional view that RNA only functions intracellularly. However, it is not well understood how cell-surface RNA (csRNA) is stably present on the plasma membrane and what functions it performs. We answer the pressing questions in the emerging field by taking integrated omic-wide approaches and multiple orthogonal validatory methods. Firstly, we exploited the RNA-sensing ability of TLR7 as a specific recombinant probe to detect csRNA. Coupling it with a genome-wide CRISPR-Cas9- knockout screening, we identified heparan sulfate (HS) as a crucial factor for RNA presentation on cells. Using the TLR7 probe, cell surface proximity labelling revealed that these HS-associated csRNAs (hepRNAs) are in vicinity with a plethora of RNA-binding proteins. The compelling observation led us to a molecular model where HS, RNA and RBP form ternary complexes at cell surface. A novel photochemical RNA-protein crosslinking technology termed SCOOPS were then established to validate the termolecular model in a TLR7-orthogonal manner. Moreover, enabled by SCOOPS, we unveiled identities of hepRNA using next-generation sequencing, and identified traits in RNA primary structures that facilitate HS association. We further show that hepRNA binds to killer cell immunoglobulin-like receptor 2DL5 (KIR2DL5), recruiting the protein to cell surface and potentially enhancing receptor-ligand interactions. Our findings provide a foundation for exploring how cell-surface ribonucleoproteins contribute to immune modulation.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture, Skin

DISEASE(S): Melanoma

SUBMITTER: Dick Zijlmans  

LAB HEAD: Zeshi Li

PROVIDER: PXD061693 | Pride | 2025-11-11

REPOSITORIES: Pride