Glycosyltransferase and sulfotransferase gene expression profiles in human monocytes, dendritic cells and macrophages

Using a focused glycan-gene microarray, we compared the glycosyltransferase (GT) and sulfotransferase gene expression profiles of human monocytes, dendritic cells (DCs) and macrophages (Mϕs), isolated or differentiated from the same donors. Microarray analysis indicated that monocytes express transcripts for a full set of enzymes involved in the biosynthesis of multi-multiantennary branched N-glycans, potentially elongated by poly-N-acetyl-lactosamine chains, and of mucin-type Core 1 and Core 2 sialylated O-glycans. Monocytes also express genes involved in the biosynthesis and modification of glycosaminoglycans, but display a limited expression of GTs implicated in glycolipid synthesis. Among genes expressed in monocytes (90 out of 175), one third is significantly modulated in DCs and Mϕ respectively, most of them being increased in both cell types relative to monocytes. These changes might potentially enforce the capacity of differentiated cells to synthesize branched N-glycans and mucin-type O-glycans and to remodel cell surface proteoglycans. Stimulation of DCs and Mϕs with lipopolysaccharide caused a general decrease in gene expression, mainly affecting genes found to be positively modulated during the differentiation steps. Interestingly, although a similar set of enzymes are modulated in the same direction in mature DCs and Mϕs, cell specific genes are also differentially regulated during maturation, a phenomenon that may sustain functional specificities. Validation of this analysis was provided by quantitative real-time PCR and flow cytometry of cell surface glycan antigens. Collectively, this study implies an important modification of the pattern of glycosylation in DCs and Mϕs undergoing differentiation and maturation with potential biological consequences.