Cell surface ribonucleoproteins cluster with heparan sulfate to regulate growth factor signaling

Abstract

Receptor-ligand interactions govern a wide array of biological pathways, facilitating a cell's ability to interrogate and integrate information from the extracellular space. Here, using an unbiased genome-wide knockout screen, we identify heparan sulfate proteoglycans (HSPGs) as a major component in the organizational mechanism of cell surface glycoRNA and cell surface RNA binding proteins (csRBPs). Cleavage of mature heparan sulfate chains, knockout of N- and 6-O-sulfotransferases, overexpression of endo-6-O-sulfatases, or the addition of exogenous heparan sulfate chains with high 2-O sulfation result in marked loss in glycoRNA-csRBP clustering in U2OS cells. Functionally, we provide evidence that signal transduction by HS-dependent growth factors such as VEGF-A165 is regulated by cell surface RNAs, and in vitro VEGF-A165, selectively interacts with glycoRNAs. Our findings uncover a new molecular mechanism of controlling signal transduction of specific growth factors across the plasma membrane by the regulated assembly of glycoRNAs, csRBPs, and heparan sulfate clusters.