Expression of glycoconjugates bearing the Lewis X epitope during neural differentiation of P19 EC cells

The Lewis X (Le(x)) bearing glycolipids were noticeably increased in amount s during the course of neural differentiation of P19 FC cells induced by re tinoic acid (RA, all-trans form). Applying neoglycolipid technology and in situ TLC-LSIMS, the oligosaccharide chains of these scarce Le(x) bearing gl ycolipids were partially characterized after released by endoglycoceramidas e and subsequent conversion into neoglycolipids. In order to understand the enzymatic basis for the expression of Le(x) bearing glycolipids, we measur ed glycolipid, glycoprotein and oligosaccharide fucosyltransferase (Fuc-T) activities using appropriate substrates in P19 FC cells with or without RA treatment. All three Fuc-Ts mere increased after RA treatment and the highe st activity was in the differentiated neural cells. We then investigated th e two possible Fuc-T genes that might be responsible for these changes usin g RT-PCR analysis, Mouse Fuc-TIX (mFuc-TIX) transcript was detected in all cell types but it was only strongly expressed in RA-induced aggregates and neural cells. In the case of mouse Fuc-TIV (mFuc-TIV) gene, its transcript was only detectable in RA-induced aggregates and not found in either undiff erentiated or RA-induced neural cells. These results strongly support that RA induces only a transient expression of the mFuc-TIV gene in cell aggrega tes but a more persistent expression of the mFuc-TIX gene at the transcript ion level throughout neural cell differentiation. The mFuc-TIX gene is prob ably the main cause for the increased expression of Le(x) glycoconjugates d uring neural differentiation of P19 EC cells. (C) 2001 Federation of Europe an Biochemical Societies. Published by Elsevier Science B.V. All rights res erved.