bims-meglyc 2025-06-08 papers

Issue of 2025–06–08
four papers selected by
Silvia Radenkovic, UMC Utrecht

J Inherit Metab Dis. 2025 Jul;48(4): e70050

Impaired Proteostasis is Linked to Neurological Pathology in a Zebrafish NGLY1 Deficiency Model.

Aviv Mesika, Golan Nadav, Sapir Ben-David, Limor Kalfon, Chen Shochat, Rana Nasra, Alejandro Livoff, David Karasik, Tzipora C Falik-Zaccai.

NGLY1 is a key enzyme in the process of misfolded protein deglycosylation. Bi-allelic pathogenic variants in NGLY1 cause N-glycanase deficiency, also known as congenital disorder of deglycosylation (NGLY1-CDDG). This rare and multisystem autosomal recessive disorder is linked to a variable phenotype of global developmental delay, neuromuscular abnormalities, and alacrima, and it lacks effective treatment. We have studied the possible underlying mechanisms for the neuromuscular and ophthalmic phenotypes in an ngly1-deficient zebrafish model carrying a similar genetic variant that has also been identified in previously reported patients. We investigated phenotypic, biochemical, and molecular details underlying ngly1 deficiency using a zebrafish model. ngly1-deficient zebrafish phenotypes were characterized using histological staining, transmission electron microscopy (TEM), and micro-CT imaging. Furthermore, fish brain molecular and biochemical characterization was performed by gene expression analysis and immunoblotting techniques. Impaired proteostasis was evident in the brain of the mutant zebrafish, including accumulation of poly-ubiquitinated proteins and amyloid fibril aggregation. The mutant fish featured neuromuscular abnormalities and significant aquaporin1-protein reduction in the eyes and brain. The zebrafish model of NGLY1 deficiency provides an ideal platform for studying the molecular and biochemical mechanisms underlying NGLY1-CDDG in humans. Our novel findings of impaired protein homeostasis encompassing amyloid fibril aggregation (folding) and poly-ubiquitinated protein accumulation (degradation) in the brains of mutant zebrafish offer new insights into the brain pathology associated with NGLY1 deficiency. These discoveries may also advance our understanding of other neurodegenerative disorders and facilitate the identification of potential therapeutic targets.

Keywords: NGLY1 deficiency; amyloids; aquaporin 1; proteostasis; zebrafish

DOI: https://doi.org/10.1002/jimd.70050

Front Pharmacol. 2025 ;16 1570158

Decoding glycosylation in cardiovascular diseases: mechanisms, biomarkers, and therapeutic opportunities.

Gang Li, Kaidi Ren, Yage Jin, Yang Yang, Yi Luan.

Protein glycosylation, particularly O-GlcNAcylation, is a critical post-translational modification (PTM) that regulates cardiac and vascular functions by modulating protein stability, localization, and interactions. Dysregulated glycosylation is generally believed as a key driver in the pathogenesis of cardiovascular diseases (CVDs), contributing to adverse cardiac remodeling, mitochondrial dysfunction, metabolic dysregulation, and vascular inflammation. This review highlights the mechanistic roles of glycosylation in CVD progression, including its regulation of cardiac remodeling, mitochondrial dysfunction, and vascular inflammation. This study explored the dual role of O-GlcNAcylation in acute protection and chronic injury, emphasizing its potential as a biomarker for early diagnosis and risk stratification. Therapeutic strategies targeting glycosylation pathways, particularly O-GlcNAc transferase (OGT), and O-GlcNAcase (OGA), hold promise for addressing myocardial ischemia-reperfusion injury, diabetic cardiomyopathy, and atherosclerosis. Advances in glycosylation profiling and interdisciplinary collaboration are essential to overcome challenges such as tissue specificity and off-target effects, advancing precision cardiovascular medicine.

Keywords: O-GlcNAcylation; OGA; OGT; cardiovascular diseases; protein glycosylation

DOI: https://doi.org/10.3389/fphar.2025.1570158

Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2025 Jan 28. pii: 1672-7347(2025)01-0105-14. [Epub ahead of print]50(1): 105-118

Effects of a homozygous missense mutation in the GNE gene p.V543M on cell phenotype and its mechanisms.

Ruolan Wu, Huilong Li, Pingyun Wu, Qi Yang, Xueting Wan, Yuan Wu.

OBJECTIVES: Uridine diphospho-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) myopathy is a progressive neurodegenerative disease associated with homozygous or compound heterozygous missense mutations in the GNE gene. This study aims to explore the impact of the homozygous p.V543M mutation in on cell phenotype and to gain preliminary insights into the underlying mechanisms.
METHODS: Human embryonic kidney 293T (HEK 293T) cells were used to construct wild-type (WT-GNE) and mutant (MUT-GNE) GNE overexpression models. Western blotting and immunofluorescence were used to assess GNE protein expression levels and subcellular localization. Cell adhesion, proliferation, apoptosis, and mitochondrial membrane potential were evaluated using the cell counting kit-8 (CCK-8) assay, crystal violet staining, flow cytometry, Hoechst 33342/propidium iodide (PI) staining, and tetramethylrhodamine ethyl ester (TMRE) staining. Sialic acid synthesis levels and GNE enzymatic activity were measured, and the mRNA expression of sialic acid biosynthesis-related enzymes was quantified by real-time PCR.
RESULTS: Western blotting confirmed successful establishment of GNE overexpression models. Immunofluorescence showed significantly reduced co-localization of GNE protein with Golgin-97 in the MUT-GNE group compared to WT-GNE (Pearson's correlation coefficient: 0.65±0.08 vs 0.83±0.06, P<0.05). Compared with WT-GNE, cells in the MUT-GNE group exhibited increased adhesion, decreased proliferation, and reduced mitochondrial membrane potential (P<0.05). No significant differences in apoptosis were observed between groups. The MUT-GNE group showed reduced sialic acid production, significantly decreased kinase activity, and downregulated transcription of sialic acid biosynthesis-related enzymes compared to WT-GNE (P<0.001).
CONCLUSIONS: The p.V543M mutation in the GNE gene alters cellular phenotype by reducing GNE enzymatic activity and the transcription of sialic acid biosynthesis enzymes, ultimately impairing sialic acid production.

Keywords: GNE myopathy; cellular phenotype; mitochondria; p.V543M mutation; sialic acid; uridine diphospho-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase

DOI: https://doi.org/10.11817/j.issn.1672-7347.2025.240287

Immunol Lett. 2025 May 30. pii: S0165-2478(25)00081-1. [Epub ahead of print]276 107048

The emerging role of GlycoRNAs in immune regulation and recognition.

Nicole Montag, Pavlos Gousis, Jürgen Wittmann.

Glycosylation, the enzymatic attachment of glycans to biomolecules, is a vital post-translational modification that impacts protein stability, immune recognition, and cellular communication. Traditionally associated with proteins and lipids, recent discoveries have revealed the existence of glycosylated RNAs (glycoRNAs), expanding our understanding of RNA modifications. GlycoRNAs challenge conventional paradigms by suggesting that glycosylation may regulate RNA stability, localization, and interactions with glycan-binding proteins, such as sialic acid-binding immunoglobulin-type lectins (Siglecs) and selectins. These interactions are particularly significant in the immune system, where glycosylation plays a key role in antigen recognition, immune cell trafficking, and pathogen detection. The potential implications of glycoRNAs in immune regulation and disease are profound, with roles in autoimmune disorders, cancer, and infectious diseases. Advances in glycobiology, including mass spectrometry, RNA sequencing, glycan microarrays, and click chemistry technologies, are driving the growth of glycoRNA research and its translational applications. Understanding glycoRNAs could lead to new therapeutic opportunities, including glycoengineering, biomarker discovery, and targeted immune interventions. Despite challenges including low abundance and complex structure, research into glycoRNA is progressing rapidly, revealing their roles in immune responses and disease mechanisms. This review synthesizes the current knowledge on glycoRNAs, highlighting their emerging significance in immunology and outlining future research directions.

Keywords: Glycan-binding proteins; GlycoRNA; Glycosylation; Immune regulation; Small RNAs

DOI: https://doi.org/10.1016/j.imlet.2025.107048