American researchers show in Nature of 28 January how recently discovered glyco-RNAs influence cell signalling. These RNAs bearing sugar groups are embedded in the cell membrane, where they interact with receptors. Through this interaction, glyco-RNAs are able to, among other things, suppress blood vessel growth.
Glyco-RNAs on the cell surface have a site to which the growth factor VEGF can bind. Under normal conditions, the molecule heparan sulfate attracts VEGF to the cell membrane. Once at the membrane, VEGF binds to the VEGF receptor, thereby signalling blood vessels to grow. However, the part of VEGF that binds to heparan sulfate also fits the glyco-RNAs. When VEGF binds to a glyco-RNA, it can no longer bind to the correct receptor and is therefore unable to pass on the growth signal.
Suppressing blood vessel growth may not sound like a positive thing. Yet the researchers show, using mutant cells, that suppressing blood vessel growth can indeed be beneficial. Mutant cells lacking functional glyco-RNAs respond strongly to VEGF. This strong response leads to excessively rapid formation of blood vessels, causing those vessels to break down again just as quickly. The researchers use this to demonstrate that glyco-RNAs are important for a balanced VEGF response. Cells in blood vessels thus use glyco-RNAs to make targeted decisions about where and how quickly they grow.