These authors contributed equally to this work.
Mucolipidosis II-Related Mutations Inhibit the Exit from the Endoplasmic Reticulum and Proteolytic Cleavage of GlcNAc-1-Phosphotransferase Precursor Protein (GNPTAB)
Article first published online: 15 JAN 2014
© 2013 WILEY PERIODICALS, INC.
Volume 35, Issue 3, pages 368–376, March 2014
How to Cite
De Pace, R., Coutinho, M. F., Koch-Nolte, F., Haag, F., Prata, M. J., Alves, S., Braulke, T. and Pohl, S. (2014), Mucolipidosis II-Related Mutations Inhibit the Exit from the Endoplasmic Reticulum and Proteolytic Cleavage of GlcNAc-1-Phosphotransferase Precursor Protein (GNPTAB). Hum. Mutat., 35: 368–376. doi: 10.1002/humu.22502
Contract grant sponsors: Fundação para a Ciência e a Tecnologia (FCT) (PIC/IC/83252/2007, SFRH/BD/48103/2008); Deutsche Forschungsgemeinschaft (GRK1459, SFB877).
Communicated by Hans R. Waterham
- Issue published online: 13 FEB 2014
- Article first published online: 15 JAN 2014
- Accepted manuscript online: 25 DEC 2013 06:29AM EST
- Manuscript Accepted: 13 DEC 2013
- Manuscript Received: 9 AUG 2013
- Fundação para a Ciência e a Tecnologia. Grant Numbers: PIC/IC/83252/2007, SFRH/BD/48103/2008, SFRH/BD/48103/2008
- Deutsche Forschungsgemeinschaft. Grant Numbers: GRK1459, SFB877, SFB877
- mannose 6-phosphate;
- site-1 protease;
- lysosomal storage disorder;
Mucolipidosis (ML) II and MLIII alpha/beta are two pediatric lysosomal storage disorders caused by mutations in the GNPTAB gene, which encodes an α/β-subunit precursor protein of GlcNAc-1-phosphotransferase. Considerable variations in the onset and severity of the clinical phenotype in these diseases are observed. We report here on expression studies of two missense mutations c.242G>T (p.Trp81Leu) and c.2956C>T (p.Arg986Cys) and two frameshift mutations c.3503_3504delTC (p.Leu1168GlnfsX5) and c.3145insC (p.Gly1049ArgfsX16) present in severely affected MLII patients, as well as two missense mutations c.1196C>T (p.Ser399Phe) and c.3707A>T (p.Lys1236Met) reported in more mild affected individuals. We generated a novel α-subunit-specific monoclonal antibody, allowing the analysis of the expression, subcellular localization, and proteolytic activation of wild-type and mutant α/β-subunit precursor proteins by Western blotting and immunofluorescence microscopy. In general, we found that both missense and frameshift mutations that are associated with a severe clinical phenotype cause retention of the encoded protein in the endoplasmic reticulum and failure to cleave the α/β-subunit precursor protein are associated with a severe clinical phenotype with the exception of p.Ser399Phe found in MLIII alpha/beta. Our data provide new insights into structural requirements for localization and activity of GlcNAc-1-phosphotransferase that may help to explain the clinical phenotype of MLII patients.