Journal Article

Golgi function and dysfunction in the first COG4-deficient CDG type II patient

Ellen Reynders, François Foulquier, Elisa Leão Teles, Dulce Quelhas, Willy Morelle, Cathérine Rabouille, Wim Annaert and Gert Matthijs

in Human Molecular Genetics

Volume 18, issue 17, pages 3244-3256
Published in print September 2009 | ISSN: 0964-6906
Published online June 2009 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/ddp262
Golgi function and dysfunction in the first COG4-deficient CDG type II patient

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The conserved oligomeric Golgi (COG) complex is a hetero-octameric complex essential for normal glycosylation and intra-Golgi transport. An increasing number of congenital disorder of glycosylation type II (CDG-II) mutations are found in COG subunits indicating its importance in glycosylation. We report a new CDG-II patient harbouring a p.R729W missense mutation in COG4 combined with a submicroscopical deletion. The resulting downregulation of COG4 expression additionally affects expression or stability of other lobe A subunits. Despite this, full complex formation was maintained albeit to a lower extent as shown by glycerol gradient centrifugation. Moreover, our data indicate that subunits are present in a cytosolic pool and full complex formation assists tethering preceding membrane fusion. By extending this study to four other known COG-deficient patients, we now present the first comparative analysis on defects in transport, glycosylation and Golgi ultrastructure in these patients. The observed structural and biochemical abnormalities correlate with the severity of the mutation, with the COG4 mutant being the mildest. All together our results indicate that intact COG complexes are required to maintain Golgi dynamics and its associated functions. According to the current CDG nomenclature, this newly identified deficiency is designated CDG-IIj.

Journal Article.  8467 words.  Illustrated.

Subjects: Genetics and Genomics

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