bims-meglyc Biomed News
on Metabolic disorders affecting glycosylation
Issue of 2025–06–22
two papers selected by
Silvia Radenkovic, UMC Utrecht



  1. Proc Natl Acad Sci U S A. 2025 Jun 24. 122(25): e2422936122
      Protein-protein interactions (PPIs) are crucial for comprehending the molecular mechanisms and signaling pathways underlying diverse biological processes and disease progression. However, investigating PPIs involving membrane proteins is challenging due to the complexity and heterogeneity of glycosylation. To tackle this challenge, we developed an approach termed glycan-dependent affinity purification coupled with mass spectrometry (GAP-MS), specifically designed to characterize changes in glycoprotein PPIs under varying glycosylation conditions. GAP-MS integrates metabolic control of glycan profiles in cultured cells using small molecules referred to as glycan modifiers with affinity purification followed by mass spectrometry analysis (AP-MS). Here, GAP-MS was applied to characterize and compare the interaction networks under five different glycosylation states for four bait glycoproteins: BSG, CD44, EGFR, and SLC3A2. This analysis identified a network comprising 156 interactions, of which 131 were determined to be glycan dependent. Notably, the GAP-MS analysis of BSG provided distinct information regarding glycosylation-influenced interactions compared to the commonly used glycosylation site mutagenesis approach combined with AP-MS, emphasizing the unique advantages of GAP-MS. Collectively, GAP-MS presents distinct insights over existing methods in elucidating how specific glycosylation forms impact glycoprotein interactions. Additionally, the glycan-dependent interaction networks generated for these four glycoproteins serve as a valuable resource for guiding future functional investigations and therapeutic developments targeting the glycoproteins discussed in this study.
    Keywords:  AP–MS; glycoprotein; glycosylation; interactome; mass spectrometry
    DOI:  https://doi.org/10.1073/pnas.2422936122
  2. J Clin Invest. 2025 Jun 17. pii: e177430. [Epub ahead of print]
      Mucopolysaccharidoses (MPS) are lysosomal storage diseases caused by defects in catabolism of glycosaminoglycans. MPS I, II, III and VII, associated with lysosomal accumulation of heparan sulphate (HS), manifest with neurological deterioration and currently lack effective treatments. We report that neuraminidase 1 (NEU1) activity is drastically reduced in brain tissues of neurological MPS patients and mouse models but not in neurological lysosomal disorders without HS storage. Accumulated HS disrupts the lysosomal multienzyme complex of NEU1 with cathepsin A (CTSA), β-galactosidase (GLB1) and glucosamine-6-sulfate sulfatase (GALNS) leading to NEU1 deficiency and partial GLB1 and GALNS deficiencies in cortical tissues and iPSC-derived cortical neurons of neurological MPS patients. Increased sialylation of N-linked glycans in brains of MPS patients and mice implicated insufficient processing of sialylated glycans, except for polysialic acid. Correction of NEU1 activity in MPS IIIC mice by lentiviral gene transfer ameliorated previously identified hallmarks of the disease, including memory impairment, behavioural traits, and reduced levels of excitatory synapse markers VGLUT1 and PSD95. Overexpression of NEU1 also restored levels of VGLUT1/PSD95-positive puncta in cortical iPSC-derived MPS IIIA neurons. Our results demonstrate that HS-induced secondary NEU1 deficiency and aberrant sialylation of brain glycoproteins constitute what we believe to be a novel pathological pathway in neurological MPS spectrum crucially contributing to CNS pathology.
    Keywords:  Genetic diseases; Genetics; Glycobiology; Lysosomes; Neuroscience
    DOI:  https://doi.org/10.1172/JCI177430