Enhanced sialylation of EPO by overexpression of UDP-GlcNAc 2-epimerase/ManAc kinase containing a sialuria mutation in CHO cells.

Sialylation (e.g. expression of sialic acid) plays a crucial role for function and stability of most glycoproteins. The key enzyme for the biosynthesis of sialic acid is the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine-kinase (GNE). Mutations in the binding site of the feedback inhibitor CMP-sialic acid of the GNE leads to sialuria, a disease in which patients produce sialic acid in gram scale. Here, we report on the use in biotechnology of sialuria-mutated GNE. Expression of the sialuria-mutated GNE in CHO-cells leads to increased sialylation of recombinant expressed erythropoietin (EPO). Our data show that sialuria-mutated-GNE over-expressing cells are the perfect platform to express highly sialylated therapeutic proteins, such as EPO.