Beta3GnT2 (B3GNT2), a major polylactosamine synthase: analysis of B3GNT2-deficient mice.
The polylactosamine structure is a fundamental structure of carbohydrate chains and carries a lot of biofunctional carbohydrate epitopes. To investigate the biological function of polylactosamine chains, here we generated and analyzed knockout mice lacking the gene B3gnt2, which encodes a major polylactosamine synthase. In beta1,3-N-acetylglucosaminyltransferase (B3gnt2) B3gnt2-deficient (B3gnt2-/-) mice, the number of polylactosamine structures was markedly lower than in wild-type mice. Flow cytometry, LEL lectin-blotting, and glycan analysis by metabolic labeling demonstrated that the amount of polylactosamine chains on N-glycans was greatly reduced in the tissues of B3gnt2-/- mice. We examined whether immunological abnormalities were present in B3gnt2-/- mice. We screened polylactosamine-carrying molecules of wild-type mice by lectin microarray analysis and found that polylactosamine was present on CD28 and CD19, two established immune co-stimulatory molecules. Polylactosamine levels on these molecules were lower in B3gnt2-/- mice than in wild-type mice. B3gnt2-/- T cells were more sensitive to the induction of intracellular Ca2+ flux on stimulation with anti-CD3epsilon/CD28 antibodies and proliferated more strongly than wild-type T cells. B3gnt2-/- B cells also showed hyperproliferation on BCR stimulation. These results showed that hyperactivation of lymphocytes occurred due to a lack of polylactosamine on receptor molecules in B3gnt2-/- mice. This finding indicates that polylactosamine has an important role in immunological biofunctions. We can therefore attempt to identify the in vivo biological function of glycans using glycogene-deficient mice.
Togayachi
Akira
A
Research Center for Medical Glycoscience (RCMG), National Institute of Advanced Industrial Science and Technology (AIST), Central-2 OSL, 1-1-1 Umezono, Tsukuba, Ibaraki, Japan.
Kozono
Yuko
Y
Kuno
Atsushi
A
Ohkura
Takashi
T
Sato
Takashi
T
Hirabayashi
Jun
J
Ikehara
Yuzuru
Y
Narimatsu
Hisashi
H
D000606:Amino Sugars / Q000378:metabolism*; D000818:Animals; D015536:Down-Regulation; D005434:Flow Cytometry; D005838:Genotype; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D046228:Microarray Analysis; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D011134:Polysaccharides / Q000378:metabolism*
D000606:Amino Sugars; D011134:Polysaccharides; C066929:polylactosamine; D017351:N-Acetylglucosaminyltransferases; C428132:B3GNT2 protein, human