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Increased levels of fucosyltransferase IX and carbohydrate Lewis x adhesion determinant in human NT2N neurons
Author(s) -
Brito Catarina,
Escrevente Cristina,
Reis Celso A.,
Lee Virginia M.Y.,
Trojanowski John Q.,
Costa Júlia
Publication year - 2007
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.21230
Subject(s) - neurite , biology , fucosyltransferase , microbiology and biotechnology , biochemistry , western blot , blot , enzyme , in vitro , gene
The expression of the fucosylated carbohydrate Lewis x (Le x ) determinant (Gal(β1–4)[Fuc(α1–3)]GlcNAc‐R) has been found in glycoproteins, proteoglycans, and glycolipids from the nervous system. Evidence suggests its association with cell–cell recognition, neurite outgrowth, and neuronal migration during central nervous system development. In the present work, we detected increased levels of Le x in differentiated human NT2N neurons cultured in vitro. To identify which fucosyltransferase (FUT) synthesized the Le x in NT2N neurons, RT‐PCR, FUT substrate specificity and Western blot analysis were carried out. Strong activity toward acceptors Galβ4GlcNAc‐O‐R and Fucα2Galβ4GlcNAc‐O‐R [R = ‐(CH 2 ) 3 NHCO(CH 2 ) 5 NH‐biotin], together with strong FUT9 detection by Western blot and presence of transcripts showed that FUT9 was the enzyme associated with Le x biosynthesis in NT2N neurons. Le x was detected at the plasma membrane of NT2N neurons, in lysosomes marked with lysosomal‐associated membrane protein 1 (LAMP‐1), and it was found for the first time to colocalize with the tetanus neurotoxin‐insensitive vesicle‐associated membrane protein (TI‐VAMP) that defines the TI‐VAMP exocytic compartment that is involved in neurite outgrowth. Furthermore, incubation with anti‐Le x monoclonal antibody L5 led to impaired adhesion of NT2N neurons to the surface matrix and inhibited neurite initiation. In conclusion, FUT9 and its product Le x are detected specifically in human NT2N neurons and our results indicate that they underlie cell differentiation, cell adhesion, and initiation of neurite outgrowth in those neurons. © 2007 Wiley‐Liss, Inc.