N-linked polylactosamine glycan synthesis is regulated by co-expression of beta3GnT2 and GCNT2
Department of Cell and Developmental Biology
Medical Subject Headings
Animals; Embryo, Mammalian; Female; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; HEK293 Cells; Humans; Mice; Mice, Knockout; N-Acetylglucosaminyltransferases; Polysaccharides; Pregnancy
Cell Biology | Cellular and Molecular Physiology
Poly-N-acetyllactosamine (PLN) is a unique glycan composed of repeating units of the common disaccharide (Galbeta1,4-GlcNAcbeta1,3)n . The expression of PLN on glycoprotein core structures minimally requires enzyme activities for beta1,4-galactosyltransferase (beta4GalT) and beta1,3-N-acetylglucosminyltransferase (beta3GnT). Because beta4GalTs are ubiquitous in most cells, PLN expression is generally ascribed to the tissue-specific transcription of eight known beta3GnT genes in mice. In the olfactory epithelium (OE), beta3GnT2 regulates expression of extended PLN chains that are essential for axon guidance and neuronal survival. N-glycan branching and core composition, however, can also modulate the extent of PLN modification. Here, we show for the first time that the beta1,6-branching glycosyltransferase GCNT2 (formerly known as IGnT) is expressed at high levels specifically in the OE and other sensory ganglia. Postnatally, GCNT2 is maintained in mature olfactory neurons that co-express beta3GnT2 and PLN. This highly specific co-expression suggests that GCNT2 and beta3GnT2 function cooperatively in PLN synthesis. In support of this, beta3GnT2 and GCNT2 co-transfection in HEK293T cells results in high levels of PLN expression on the cell surface and on adenylyl cyclase 3, a major carrier of PLN glycans in the OE. These data clearly suggest that GCNT2 functions in vivo together with beta3GnT2 to determine PLN levels in olfactory neurons by regulating beta1,6-branches that promote PLN extension.
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Citation: Henion TR, Schwarting GA. N-linked polylactosamine glycan synthesis is regulated by co-expression of β3GnT2 and GCNT2. J Cell Physiol. 2014 Apr;229(4):471-8. doi: 10.1002/jcp.24467. Link to article on publisher's site