Scientists in the Bertozzi at Staford University have published surprising observations of glycan sugars attached directly to RNA during glycosylation. Until now, evidence showed RNA attached to a protein, which is attached to a glycan sugar. This observation could change the understanding of non-coding RNA's role in gene expression, transcription, and disease.
The Bertozzi lab observed glycans attached to RNA, but it is unclear how and where the molecules are attached. Skeptical of their initial observation, the lab attempted to separate the molecules with proteases. After treating with a glycan-digesting enzyme, only RNA molecules remained in the mixture. Likewise, after treatment with an RNA protease, only glycan sugars remained. Since the Bertozzi lab experiments began as labeling glycoproteins in human cell lines, the experiments were repeated in mice and hamster cell lines with the same outcome. Each experiment provided more evidence that RNA and glycan sugars could be attached without the linkage of a protein.
Bertozzi et. al., Possible structure of RNA (bottom) connected to a glycan (top) by an unknown intermediary.
Glycosylation is essential for many cell processes, including protein folding and cell-to-cell adhesion. During this process, RNA is located in either the nucleus or cytosol. Glycans are located in either the endoplasmic reticulum or the Golgi body. One of the molecules is moving to a cell organ that it was previously unknown to be active in, and scientists must figure out how this transition happens.