Chondroitin 4-O-sulfotransferase-1 regulates the chain length of chondroitin sulfate in co-operation with chondroitin N-acetylgalactosaminyltransferase-2.
Previously, we demonstrated that sog9 cells, a murine L cell mutant, are deficient in the expression of C4ST (chondroitin 4-O-sulfotransferase)-1 and that they synthesize fewer and shorter CS (chondroitin sulfate) chains. These results suggested that C4ST-1 regulates not only 4-O-sulfation of CS, but also the length and amount of CS chains; however, the mechanism remains unclear. In the present study, we have demonstrated that C4ST-1 regulates the chain length and amount of CS in co-operation with ChGn-2 (chondroitin N-acetylgalactosaminyltransferase 2). Overexpression of ChGn-2 increased the length and amount of CS chains in L cells, but not in sog9 mutant cells. Knockdown of ChGn-2 resulted in a decrease in the amount of CS in L cells in a manner proportional to ChGn-2 expression levels, whereas the introduction of mutated C4ST-1 or ChGn-2 lacking enzyme activity failed to increase the amount of CS. Furthermore, the non-reducing terminal 4-O-sulfation of N-acetylgalactosamine residues facilitated the elongation of CS chains by chondroitin polymerase consisting of chondroitin synthase-1 and chondroitin-polymerizing factor. Overall, these results suggest that the chain length of CS is regulated by C4ST-1 and ChGn-2 and that the enzymatic activities of these proteins play a critical role in CS elongation.
Department of Biochemistry, Kobe Pharmaceutical University, Kobe 658-8558, Japan.
Tomomi
T
Izumikawa
Yuka
Y
Okuura
Toshiyasu
T
Koike
Naoki
N
Sakoda
Hiroshi
H
Kitagawa
D000116:Acetylgalactosamine / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002807:Chondroitin / Q000378:metabolism; D002809:Chondroitin Sulfates / Q000378:metabolism*; D006801:Humans; D007739:L Cells; D051379:Mice; D017350:N-Acetylgalactosaminyltransferases / Q000378:metabolism*; D013379:Substrate Specificity; D015238:Sulfotransferases / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D002807:Chondroitin; D002809:Chondroitin Sulfates; D017350:N-Acetylgalactosaminyltransferases; D015238:Sulfotransferases; C019893:chondroitin 4-sulfotransferase; D000116:Acetylgalactosamine