Expression profiles of genes encoding glycosyltransferases synthesizing the glycosaminoglycan linker region during chondrogenic differentiation of ATDC5 cells

Several glycosaminoglycans (GAGs) are covalently linked to specific serine residues in the core proteins of proteoglycans at the GAG-protein linker region, synthesized by five glycosyltransferases, each encoded by Xylt1, Xylt2, B4galt7, B3galt6, and B3gat3. We quantitatively analyzed the mRNA expression levels of these five genes in the undifferentiated, differentiated, and well-differentiated stages of ATDC5 cell line, which enables the monitoring of chondrogenic differentiation. Xylt1 and B4galt7 expressions were markedly increased in the well-differentiated cells, whereas B3galt6 expression was slightly inhibited. In contrast, Xylt2 and B3gat3 expressions remained unaltered across the three stages. These results help us better understand the regulatory mechanisms of the linker region synthesis in chondrocytes. ATDC5 is a useful in vitro model for examining these mechanisms.