Kwak, Chan-YeongPark, Seung-YeolLee, Chung-GeunOkino, NozomuIto, MakotoKim, Jung Hoe2017-12-062017Kwak, Chan-Yeong, Seung-Yeol Park, Chung-Geun Lee, Nozomu Okino, Makoto Ito, and Jung Hoe Kim. 2017. “Enhancing the sialylation of recombinant EPO produced in CHO cells via the inhibition of glycosphingolipid biosynthesis.” Scientific Reports 7 (1): 13059. doi:10.1038/s41598-017-13609-4. http://dx.doi.org/10.1038/s41598-017-13609-4.http://nrs.harvard.edu/urn-3:HUL.InstRepos:34492375Sialylation regulates the in vivo half-life of recombinant therapeutic glycoproteins, affecting their therapeutic efficacy. Levels of the precursor molecule cytidine monophospho-N-acetylneuraminic acid (CMP-Neu5Ac) are considered a limiting factor in the sialylation of glycoproteins. Here, we show that by reducing the amount of intracellular CMP-Neu5Ac consumed for glycosphingolipid (GSL) biosynthesis, we can increase the sialylation of recombinant human erythropoietin (rhEPO) produced in CHO cells. Initially, we found that treating CHO cells with a potent inhibitor of GSL biosynthesis increases the sialylation of the rhEPO they produce. Then, we established a stable CHO cell line that produces rhEPO in the context of repression of the key GSL biosynthetic enzyme UDP-glucose ceramide glucosyltransferase (UGCG). These UGCG-depleted cells show reduced levels of gangliosides and significantly elevated levels of rhEPO sialylation. Upon further analysis of the resulting N-glycosylation pattern, we discovered that the enhanced rhEPO sialylation could be attributed to a decrease in neutral and mono-sialylated N-glycans and an increase in di-sialylated N-glycans. Our results suggest that the therapeutic efficacy of rhEPO produced in CHO cells can be improved by shunting intracellular CMP-Neu5Ac away from GSL biosynthesis and toward glycoprotein sialylation.en-USJournal Article2017-12-0610.1038/s41598-017-13609-4