ABSTRACT
Sialic acids comprise a family of terminal sugars essential for a variety of biological recognition systems. N-Propanoylmannosamine, an unphysiological sialic acid precursor, is taken up and metabolized by mammalian cells resulting in oligosaccharide-bound N-propanoylneuraminic acid. N-Propanoylmannosamine, applied to endogenously hyposialylated subclones of the myeloid leukemia HL60 and of the B-cell lymphoma BJA-B, both deficient in UDP-N-acetylglucosamine 2-epimerase, is efficiently metabolized to CMP-N-propanoylneuraminic acid resulting in up to 85% of glycoconjugate-associated sialic acids being unphysiological N-propanoylneuraminic acid. Thus, UDP-N-acetylglucosamine 2-epimerase-deficient cell lines provide an important experimental progress in engineering cells to display an almost homogeneous population of defined, structurally altered sialic acids.
Subject(s)
Carbohydrate Epimerases/metabolism , Cytidine Monophosphate N-Acetylneuraminic Acid/metabolism , Escherichia coli Proteins , Cell Line , Cell Membrane/metabolism , Cytidine Monophosphate N-Acetylneuraminic Acid/chemistry , Flow Cytometry , Humans , Neuraminic Acids/metabolism , Tumor Cells, CulturedABSTRACT
The biological half-life time of many glycoproteins is regulated via terminal sialic acids. In this study we determined the half-lives of two different cell adhesion molecules, CEACAM1 and the alpha1-integrin subunit, in PC12-cells before and after biochemical engineering the side chain of sialic acids by the use of N-propanoylmannosamine. Both are transmembrane glycoproteins. While the immunoglobulin superfamily member CEACAM1 mediates homophilic cell-cell adhesion the alpha1-integrin subunit is involved in cell-matrix interactions. We found that the half-life of the highly sialylated CEACAM1 is increased from 26 to 40 h by replacement of the N-acetylneuraminic acid by the novel, engineered N-propanoylneuraminic acids, whereas the half-life of the alpha1-integrin subunit remains unaffected under the same conditions. This demonstrates that biochemical engineering not only modulates the structure of cell surface sialic acids, but that biochemical engineering also influences biological stability of defined glycoproteins.