Disease mutations in CMP-sialic acid transporter SLC35A1 result in abnormal alpha-dystroglycan O-mannosylation, independent from sialic acid

Moniek Riemersma, Julia Sandrock, Thomas J. Boltje, Christian Bull, Torben Heise, Angel Ashikov, Gosse J. Adema, Hans van Bokhoven, Dirk J. Lefeber*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

24 Citations (Web of Science)

Abstract

Binding of cellular ?-dystroglycan (?-DG) to its extracellular matrix ligands is fully dependent on a unique O-mannose-linked glycan. Disrupted O-mannosylation is the hallmark of the muscular dystrophy-dystroglycanopathy (MDDG) syndromes. SLC35A1, encoding the transporter of cytidine 5'-monophosphate-sialic acid, was recently identified as MDDG candidate gene. This is surprising, since sialic acid itself is dispensable for ?-DG-ligand binding. In a novel SLC35A1-deficient cell model, we demonstrated a lack of ?-DG O-mannosylation, ligand binding and incorporation of sialic acids. Removal of sialic acids from HAP1 wild-type cells after incorporation or preventing sialylation during synthesis did not affect ?-DG O-mannosylation or ligand binding but did affect sialylation. Lentiviral-mediated complementation with the only known disease mutation p.Q101H failed to restore deficient O-mannosylation in SLC35A1 knockout cells and partly restored sialylation. These data indicate a role for SLC35A1 in ?-DG O-mannosylation that is distinct from sialic acid metabolism. In addition, human SLC35A1 deficiency can be considered as a combined disorder of ?-DG O-mannosylation and sialylation, a novel variant of the MDDG syndromes. ? The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Original languageEnglish
Pages (from-to)2241-2246
JournalHuman Molecular Genetics
Volume24
Issue number8
DOIs
Publication statusPublished - 15 Apr 2015

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