Heparan sulfate synthesized by mouse embryonic stem cells deficient in NDST1 and NDST2 is 6-O-sulfated but contains no N-sulfate groups.
Heparan sulfate structure differs significantly between various cell types and during different developmental stages. The diversity is created during biosynthesis by sulfotransferases, which add sulfate groups to the growing chain, and a C5-epimerase, which converts selected glucuronic acid residues to iduronic acid. All these modifications are believed to depend on initial glucosamine N-sulfation carried out by the enzyme glucosaminyl N-deacetylase/N-sulfotransferase (NDST). Here we report that heparan sulfate synthesized by mouse embryonic stem cells deficient in NDST1 and NDST2 completely lacks N-sulfation but still contains 6-O-sulfate groups, demonstrating that 6-O-sulfation can occur without prior N-sulfation. Reverse transcriptase-PCR analysis indicates that all three identified 6-O-sulfotransferases are expressed by the cells, 6-O-sulfotransferase-1 being the dominating form. The 6-O-sulfated polysaccharide lacking N-sulfate groups also contains N-unsubstituted glucosamine units, raising questions about how these units are generated.
Department of Medical Biochemistry and Microbiology, BMC, Box 582, SE-751 23 Uppsala, Sweden.
Katarina
K
Holmborn
Johan
J
Ledin
Emanuel
E
Smeds
Inger
I
Eriksson
Marion
M
Kusche-Gullberg
Lena
L
Kjellén
D000581:Amidohydrolases / Q000235:genetics* / Q000502:physiology; D000818:Animals; D001755:Blastocyst / Q000378:metabolism; D002238:Carbohydrate Epimerases / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D018076:DNA, Complementary / Q000378:metabolism; D004622:Embryo, Mammalian / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D005944:Glucosamine / Q000737:chemistry; D020723:Glucuronic Acid / Q000378:metabolism; D006025:Glycosaminoglycans; D006497:Heparan Sulfate / Q000096:biosynthesis*; D007067:Iduronic Acid / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009608:Nitrous Acid / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000378:metabolism; D013431:Sulfates / Q000737:chemistry; D015238:Sulfotransferases / Q000235:genetics* / Q000502:physiology; D013455:Sulfur / Q000378:metabolism*
D000581:Amidohydrolases; D002238:Carbohydrate Epimerases; D018076:DNA, Complementary; D005944:Glucosamine; D020723:Glucuronic Acid; D006025:Glycosaminoglycans; D006497:Heparan Sulfate; D007067:Iduronic Acid; D009608:Nitrous Acid; D011134:Polysaccharides; D013431:Sulfates; D015238:Sulfotransferases; D013455:Sulfur; C491855:Ndst2 protein, mouse; C021350:heparitin sulfotransferase; C430881:heparin-heparan sulfate-glucuronic acid C5-epimerase