POMK regulates dystroglycan function via LARGE1-mediated elongation of matriglycan
- Howard Hughes Medical Institute, University of Iowa Roy J and Lucille A Carver College of Medicine, United States
- Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health & Great Ormond Street Hospital, United Kingdom
- University of Iowa, United States
- Peking University, China
- University of California, San Diego, United States
- UCL Great Ormond Street Institute of Child Health, United Kingdom
- Howard Hughes Medical Institute, University of Iowa Roy J. and Lucille A. Carver College of Medicine, United States
Abstract
Matriglycan [-GlcA-β1,3-Xyl-α1,3-]n serves as a scaffold in many tissues for extracellular matrix proteins containing laminin-G domains including laminin, agrin, and perlecan. Like-acetylglucosaminyltransferase-1 (LARGE1) synthesizes and extends matriglycan on α-dystroglycan (α-DG) during skeletal muscle differentiation and regeneration; however, the mechanisms which regulate matriglycan elongation are unknown. Here, we show that Protein O-Mannose Kinase (POMK), which phosphorylates mannose of core M3 (GalNac-β1,3-GlcNac-β1,4-Man) preceding matriglycan synthesis, is required for LARGE1-mediated generation of full-length matriglycan on α-DG (~150 kDa). In the absence of Pomk gene expression in mouse skeletal muscle, LARGE1 synthesizes a very short matriglycan resulting in a ~90 kDa α-DG which binds laminin but cannot prevent eccentric contraction-induced force loss or muscle pathology. Solution NMR spectroscopy studies demonstrate that LARGE1 directly interacts with core M3 and binds preferentially to the phosphorylated form. Collectively, our study demonstrates that phosphorylation of core M3 by POMK enables LARGE1 to elongate matriglycan on α-DG, thereby preventing muscular dystrophy.
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All data generated or analysed during this study are included in the manuscript.
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Author details
Funding
Paul D. Wellstone Muscular Dystrophy Specialized Research Center grant (1U54NS053672)
- Kevin P Campbell
Great Ormond Street Hospital for Children NHS Foundation Trust and University College
- Silvia Torelli
- Francesco Muntoni
Medical Scientist Training Program Grant by the National Institute of General Medical Sciences (5 T32 GM007337)
- Ameya S Walimbe
Howard Hughes Medical Institute
- Kevin P Campbell
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. All animal experiments were approved by the Institutional Animal Care and Use Committee (IACUC) protocols of the University of Iowa (#0081122).
Human subjects: All procedures performed in this study involving human participants were in accordance with the ethical standards of NHS Health Research Authority (REC ref: 06/Q0406/33). We acknowledge and thank the BRC/MRC Centre for Neuromuscular Diseases Biobank for providing patients' serum and biopsy samples. We confirm that informed consent was provided to the patient and family regarding the nature of the genetic studies to be performed upon collection of samples and is available for our patient.
Copyright
© 2020, Walimbe et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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POMK regulates dystroglycan function via LARGE1-mediated elongation of matriglycan
eLife 9:e61388.
https://doi.org/10.7554/eLife.61388
