Alpha 1,6-linked fucose affects the expression and stability of polysialic acid-carrying glycoproteins in Chinese hamster ovary cells.
To determine the effect of alpha1,6-linked fucose modification of N-glycans on the expression of polysialic acids (PSAs), the expression of PSAs in a fucose-lacking mutant of Chinese hamster ovary (CHO) cells, Lec13, was compared with that in CHO K1 cells. PSA synthase activity in these cells and the antennary structures of N-glycans associated with the neural adhesion molecule (NCAM), which is a major PSA-carrying glycoprotein, did not differ between the two types of cells. Metabolic labeling of cells with [3H]glucosamine for 48 h followed by immunoprecipitation with anti-PSA monoclonal antibodies revealed that the amount of labeled PSA-carrying glycoproteins obtained from Lec13 cells was 10-times less than that from K1 cells, although the incorporation of [3H]glucosamine into total extracts and NCAM was almost the same. In contrast, when cells were pulse labeled with [35S]methionine followed by a 1 h chase, there was not such a great difference in PSA-carrying protein synthesis between K1 and Lec13 cells. However, during a prolonged chase period, PSA-carrying proteins rapidly decreased in Lec13 cells, whereas those in K1 cells did not change. The degradation of PSA-carrying glycoproteins in Lec13 cells was partly prevented when the cells were grown in fucose-containing medium. Therefore, fucose modification of core N-glycans may affect the efficient expression of PSAs through the intracellular stability of PSA-carrying glycoproteins.
Molecular Glycobiology, Frontier Research Program, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama, 351-0198, Japan.
N
N
Kojima
Y
Y
Tachida
S
S
Tsuji
D000818:Animals; D000911:Antibodies, Monoclonal; D016466:CHO Cells; D002999:Clone Cells; D006224:Cricetinae; D005643:Fucose / Q000172:deficiency / Q000378:metabolism*; D005944:Glucosamine / Q000378:metabolism; D006023:Glycoproteins / Q000096:biosynthesis / Q000378:metabolism*; D007700:Kinetics; D019006:Neural Cell Adhesion Molecules / Q000096:biosynthesis*; D012794:Sialic Acids / Q000096:biosynthesis / Q000378:metabolism*; D012799:Sialyltransferases / Q000378:metabolism*; D014316:Tritium
D000911:Antibodies, Monoclonal; D006023:Glycoproteins; D019006:Neural Cell Adhesion Molecules; D012794:Sialic Acids; C021319:polysialic acid; D014316:Tritium; D005643:Fucose; C046778:CMP-N-acetylneuraminate-poly-alpha-2,8-sialosyl sialyltransferase; D012799:Sialyltransferases; D005944:Glucosamine