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Licensed Unlicensed Requires Authentication Published by De Gruyter June 1, 2005

Regulation of sialic acid O-acetylation in human colon mucosa

Y. Shen , J. Tiralongo , G. Kohla and R. Schauer
From the journal

Abstract

The expression of O-acetylated sialic acids in human colonic mucins is developmentally regulated, and a reduction of O-acetylation has been found to be associated with the early stages of colorectal cancer. Despite this, however, little is known about the enzymatic process of sialic acid O-acetylation in human colonic mucosa. Recently, we have reported on a human colon sialate 7(9)-O-acetyltransferase capable of incorporating acetyl groups into sialic acids at the nucleotidesugar level [Shen et al., Biol. Chem. 383 (2002), 307317]. In this report, we show that the CMP-N-acetyl-neuraminic acid (CMPNeu5Ac) and acetyl-CoA (AcCoA) transporters are critical components for the O-acetylation of CMPNeu5Ac in Golgi lumen, with specific inhibition of either transporter leading to a reduction in the formation of CMP-5-Nacetyl-9-O-acetylneuraminic acid (CMP-Neu5,9Ac2). Moreover, the finding that 5-Nacetyl-9-O-acetylneuraminic acid (Neu5,9Ac2) could be transferred from neo-synthesised CMP-Neu5,9Ac2 to endogenous glycoproteins in the same Golgi vesicles, together with the observation that asialofetuin and asialo-human colon mucin are much better acceptors for Neu5,9Ac2 than asialo-bovine submandibular gland mucin, suggests that a sialyltransferase exists that preferentially utilises CMPNeu5,9Ac2 as the donor substrate, transferring Neu5,9Ac2 to terminal Galβ1,3(4)R- residues.

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Published Online: 2005-06-01
Published in Print: 2004-02-05

Copyright © 2004 by Walter de Gruyter GmbH & Co. KG

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