Activities and expression pattern of the carbohydrate sulfotransferase GlcNAc6ST-3 (I-GlcNAc6ST): functional implications.
In recent years, a family of five GlcNAc-6-O-sulfotransferases, called the GlcNAc6STs, has been molecularly cloned. One of these, GlcNAc6ST-2 (originally named HEC-GlcNAc6ST or LSST), shows a very restricted expression at the mRNA level in high endothelial cells (HECs) of lymph nodes high endothelial venules (HEVs). This enzyme has been shown to be involved in elaborating the 6-sulfo sLex structure on a set of mucin-like acceptors within HECs, thus providing a critical recognition determinant for L-selectin during the process of lymphocyte homing to lymph nodes. Limited information has been available about the closely related sulfotransferase known as GlcNAc6ST-3 (I-GlcNAc6ST). Here, employing transfection experiments with a series of glycoprotein acceptors, we report that this sulfotransferase has a marked preference for sulfating O-linked sugars of mucin-type acceptors, whereas other sulfotransferases in the family (GlcNAc6ST-1, GlcNAc6ST-2) and a Gal-6-O-sulfotransferase exhibit strong activity on both mucin-type acceptors and glycoproteins with predominantly N-linked chains. PCR analysis of cDNAs derived from a panel of tissues and purified cell populations confirms the strong expression of GlcNAc6ST-3 in gut-associated tissues and extends the expression to include lymphocytes. In contrast to GlcNAc6ST-2, GlcNAc6ST-3 transcripts are present minimally, if at all, in HECs; moreover, this enzyme is not able to generate the 6-sulfo sLex epitope in transfected cells. These latter findings argue that GlcNAc6ST-3 is not involved in generating HEV-expressed ligands for L-selectin.
Lee
Jin Kyu
JK
Department of Anatomy, University of California, San Francisco, CA 94143-0452, USA.
Bistrup
Annette
A
van Zante
Annemieke
A
Rosen
Steven D
SD
D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002522:Chlorocebus aethiops; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D019041:L-Selectin / Q000378:metabolism; D008024:Ligands; D008208:Lymphatic System / Q000201:enzymology; D008297:Male; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013379:Substrate Specificity; D013431:Sulfates / Q000378:metabolism; D015238:Sulfotransferases / Q000235:genetics* / Q000378:metabolism*
D007527:Isoenzymes; D008024:Ligands; D009844:Oligosaccharides; D013431:Sulfates; D019041:L-Selectin; D015238:Sulfotransferases