Abstract
Molecules on the cell surface play crucial roles in cellular material exchange, molecular recognition, signal transduction, migration, growth, differentiation, and pathological processes. Due to the lack of simple and effective methods, little is known about the nucleic acids on the cell surface. In this paper, using synthetic DNA G4 as probes, we found that a significant amount of RNA was associated with the cell surface during cell culture. Both RNA and DNA G4 were found to bind RNA-binding proteins on the cell surface, such as nucleolin. The amount of RNA bound to the cell surface varies greatly among different cell lines, and increases over time after treatment with proteases or RNase A. The RNA bound on the cell surface is primarily internal cellular RNA fragments between 20-100 nt in length, including microRNAs. Addition of RNase A in the culture medium to remove cell surface RNA can inhibit cell growth and promote cell migration. These results provide a preliminary understanding of RNA bound to the cell surface and offer new perspectives on the metabolism and function of nucleic acids inside and outside the cells.