bims-meglyc 2024-11-24 papers

Issue of 2024–11–24
four papers selected by
Silvia Radenkovic, UMC Utrecht

Cell Rep. 2024 Nov 18. pii: S2211-1247(24)01327-5. [Epub ahead of print]43(11): 114976

O-GlcNAcylation modulates expression and abundance of N-glycosylation machinery in an inherited glycosylation disorder.

Courtney Matheny-Rabun, Sneha S Mokashi, Silvia Radenkovic, Kali Wiggins, Lynn Dukes-Rimsky, Peggi Angel, Bart Ghesquiere, Tamas Kozicz, Richard Steet, Eva Morava, Heather Flanagan-Steet.

Core components of the N-glycosylation pathway are known, but the metabolic and post-translational mechanisms regulating this pathway in normal and disease states remain elusive. Using a multi-omic approach in zebrafish, we discovered a mechanism whereby O-GlcNAcylation directly impacts the expression and abundance of two rate-limiting proteins in the N-linked glycosylation pathway. We show in a model of an inherited glycosylation disorder PMM2-CDG, congenital disorders of glycosylation that phosphomannomutase deficiency is associated with increased levels of UDP-GlcNAc and protein O-GlcNAcylation. O-GlcNAc modification increases the transcript and protein abundance of both NgBR and Dpagt1 in pmm2m/m mutants. Modulating O-GlcNAc levels, NgBR abundance, or Dpagt1 activity exacerbated the cartilage phenotypes in pmm2 mutants, suggesting that O-GlcNAc-mediated increases in the N-glycosylation machinery are protective. These findings highlight nucleotide-sugar donors as metabolic sensors that regulate two spatially separated glycosylation pathways, demonstrating how their coordination is relevant to disease severity in the most common congenital disorder of glycosylation.

Keywords: CDG; CP: Molecular biology; O-GlcNAc; disease modifiers; glycosylation; sugar metabolism; zebrafish

DOI: https://doi.org/10.1016/j.celrep.2024.114976

Nat Commun. 2024 Nov 18. 15(1): 9970

CRISPR screens and lectin microarrays identify high mannose N-glycan regulators.

C Kimberly Tsui, Nicholas Twells, Jenni Durieux, Emma Doan, Jacqueline Woo, Noosha Khosrojerdi, Janiya Brooks, Ayodeji Kulepa, Brant Webster, Lara K Mahal, Andrew Dillin.

Glycans play critical roles in cellular signaling and function. Unlike proteins, glycan structures are not templated from genetic sequences but synthesized by the concerted activity of many genes, making them historically challenging to study. Here, we present a strategy that utilizes CRISPR screens and lectin microarrays to uncover and characterize regulators of glycosylation. We applied this approach to study the regulation of high mannose glycans - the starting structure of all asparagine(N)-linked-glycans. We used CRISPR screens to uncover the expanded network of genes controlling high mannose levels, followed by lectin microarrays to fully measure the complex effect of select regulators on glycosylation globally. Through this, we elucidated how two high mannose regulators - TM9SF3 and the CCC complex - control complex N-glycosylation via regulating Golgi morphology and function. Notably, this allows us to interrogate Golgi function in-depth and reveals that similar disruption to Golgi morphology can lead to drastically different glycosylation outcomes. Collectively, this work demonstrates a generalizable approach for systematically dissecting the regulatory network underlying glycosylation.

DOI: https://doi.org/10.1038/s41467-024-53225-1

Ann Hematol. 2024 Nov 22.

Novel biallelic GNE variants identified in a patient with chronic thrombocytopenia without any symptoms of myopathy.

Shota Tsuda, Atsushi Sakamoto, Hiroyuki Kawaguchi, Toru Uchiyama, Tadashi Kaname, Kumiko Yanagi, Shinji Kunishima, Akira Ishiguro.

GNE encodes a rate-limiting enzyme that regulates the biosynthesis of a sialic acid precursor. As sialic acids are critical for the platelet membrane and muscle fibers, GNE variants cause GNE-related thrombocytopenia and GNE-related myopathy. Here, we report a neonate with thrombocytopenia that initially met the criteria for neonatal allo-immune thrombocytopenia (NAIT) but was resistant to treatments and then revealed novel biallelic heterozygous GNE variants without any symptoms of myopathy when diagnosed. NAIT was initially diagnosed due to alloantibodies against HPA5 and its mismatch between the patient and his mother. However, intravenous immunoglobulin therapy and platelet transfusions showed minimal improvement in the platelet count. Platelet counts remained around 60 × 109/L, suggesting congenital thrombocytopenia. Gene panel sequencing at the age of 13 identified biallelic pathogenic variants of GNE. The patient did not exhibit any symptoms of muscular weakness, suggesting GNE-related myopathy. We demonstrated a GNE-related thrombocytopenia patient with novel biallelic heterozygous GNE variants. Clinical trials have involved the use of sialic acids or their precursors, as well as gene therapy, to treat GNE-related myopathy, which may slow or halt the progression of the disease. Therefore, early diagnosis of this disease may significantly impact its clinical course.

Keywords: GNE; Myopathy; NAIT; Thrombocytopenia

DOI: https://doi.org/10.1007/s00277-024-06104-0

bioRxiv. 2024 Nov 01. pii: 2024.10.30.621210. [Epub ahead of print]

Metabolic Control of Glycosylation Forms for Establishing Glycan-Dependent Protein Interaction Networks.

Xingyu Liu, Li Yi, Zongtao Lin, Siyu Chen, Shunyang Wang, Ying Sheng, Carlito B Lebrilla, Benjamin A Garcia, Yixuan Xie.

Protein-protein interactions (PPIs) provide essential insights into the complex molecular mechanisms and signaling pathways within cells that regulate development and disease-related phenotypes. However, for membrane proteins, the impact of various forms of glycosylation has often been overlooked in PPI studies. In this study, we introduce a novel approach, glycan-dependent affinity purification followed by mass spectrometry (GAP-MS), to assess variations in PPIs for any glycoprotein of interest under different glycosylation conditions. As a proof of principle, we selected four glycoproteins-BSG, CD44, EGFR, and SLC3A2-as baits to compare their co-purified partners across five metabolically controlled glycan conditions. The findings demonstrate the capability of GAP-MS to identify PPIs influenced by altered glycosylation states, establishing a foundation for systematically exploring the Glycan-Dependent Protein Interactome (GDPI) for other glycoproteins of interest.

DOI: https://doi.org/10.1101/2024.10.30.621210