TNF-alpha increases the carbohydrate sulfation of CD44: induction of 6-sulfo N-acetyl lactosamine on N- and O-linked glycans.
CD44 and sulfation have both been implicated in leukocyte adhesion. In monocytes, the inflammatory cytokine tumor necrosis factor alpha (TNF-alpha) stimulates CD44 sulfation, and this correlates with the induction of CD44-mediated adhesion events. However, little is known about the sulfation of CD44 or its induction by inflammatory cytokines. We determined that TNF-alpha induces the carbohydrate sulfation of CD44. CD44 was established as a major sulfated cell surface protein on myeloid cells. In the SR91 myeloid cell line, the majority of CD44 sulfation was attributed to the glycosaminoglycan chondroitin sulfate. However, TNF-alpha stimulation increased CD44 sulfation two- to threefold, largely attributed to the increased sulfation of N- and O-linked glycans on CD44. Therefore, TNF-alpha induced a decrease in the percentage of CD44 sulfation due to chondroitin sulfate and an increase due to N- and O-linked sulfation. Furthermore, TNF-alpha induced the expression of 6-sulfo N-acetyl lactosamine (LacNAc)/Lewis x on these cells, which was detected by a monoclonal antibody after neuraminidase treatment. This 6-sulfo LacNAc/Lewis x epitope was induced on N-linked and (to a lesser extent) on O-linked glycans present on CD44. This demonstrates that CD44 is modified by sulfated carbohydrates in myeloid cells and that TNF-alpha modifies both the type and amount of carbohydrate sulfation occurring on CD44. In addition, it demonstrates that TNF-alpha can induce the expression of 6-sulfo N-acetyl glucosamine on both N- and O-linked glycans of CD44 in myeloid cells.
Delcommenne
Marc
M
Department of Microbiology and Immunology, 6174 University Boulevard, University of British Columbia, Vancouver, British Columbia, V6T 1Z3 Canada.
Kannagi
Reiji
R
Johnson
Pauline
P
D000606:Amino Sugars; D050260:Carbohydrate Metabolism; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D013431:Sulfates / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
C467438:6-sulfo-LacNac; D000606:Amino Sugars; D018960:Hyaluronan Receptors; D008070:Lipopolysaccharides; D011134:Polysaccharides; D013431:Sulfates; D014409:Tumor Necrosis Factor-alpha