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Lookup NU author(s): Dr Jamie Soul
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2020 Company of Biologists Ltd. All rights reserved.Mucolipidosis type III (MLIII) gamma is a rare inherited lysosomal storage disorder caused by mutations in GNPTG encoding the γ-subunit of GlcNAc-1-phosphotransferase, the key enzyme ensuring proper intracellular location of multiple lysosomal enzymes. Patients with MLIII gamma typically present with osteoarthritis and joint stiffness, suggesting cartilage involvement. Using Gnptg knockout (Gnptgko) mice as a model of the human disease, we showed that missorting of a number of lysosomal enzymes is associated with intracellular accumulation of chondroitin sulfate in Gnptgko chondrocytes and their impaired differentiation, as well as with altered microstructure of the cartilage extracellular matrix (ECM). We also demonstrated distinct functional and structural properties of the Achilles tendons isolated from Gnptgko and Gnptab knock-in (Gnptabki) mice, the latter displaying a more severe phenotype resembling mucolipidosis type II (MLII) in humans. Together with comparative analyses of joint mobility in MLII and MLIII patients, these findings provide a basis for better understanding of the molecular reasons leading to joint pathology in these patients. Our data suggest that lack of GlcNAc-1-phosphotransferase activity due to defects in the γ-subunit causes structural changes within the ECM of connective and mechanosensitive tissues, such as cartilage and tendon, and eventually results in functional joint abnormalities typically observed in MLIII gamma patients. This idea was supported by a deficit of the limb motor function in Gnptgko mice challenged on a rotarod under fatigue-associated conditions, suggesting that the impaired motor performance of Gnptgko mice was caused by fatigue and/or pain at the joint. This article has an associated First Person interview with the first author of the paper.
Author(s): Westermann LM, Fleischhauer L, Vogel J, Jenei-Lanzl Z, Ludwig NF, Schau L, Morellini F, Baranowsky A, Yorgan TA, Lorenzo GD, Schweizer M, de Souza Pinheiro B, Guarany NR, Sperb-Ludwig F, Visioli F, Silva TO, Soul J, Hendrickx G, Wiegert JS, Schwartz IVD, Clausen-Schaumann H, Zaucke F, Schinke T, Pohl S, Danyukova T
Publication type: Article
Publication status: Published
Journal: DMM Disease Models and Mechanisms
Year: 2020
Volume: 13
Issue: 11
Print publication date: 01/11/2020
Online publication date: 06/10/2020
Acceptance date: 15/09/2020
Date deposited: 17/03/2021
ISSN (print): 1754-8403
ISSN (electronic): 1754-8411
Publisher: Company of Biologists Ltd
URL: https://doi.org/10.1242/dmm.046425
DOI: 10.1242/dmm.046425
PubMed id: 33023972
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