Dataset Information

Deciphering the Neurological Puzzle in ALG13-CDG Through Cutting-Edge Brain Organoid Modeling.

ABSTRACT: Asparagine-linked glycosylation 13 (ALG13) is an X-linked congenital disorder of glycosylation (CDG). Our study addresses the urgent need for deeper insights into ALG13-CDG characterized by significant gaps in our understanding of its pathobiology and the absence of effective treatment options. Despite extensive research on various CDG, investigations into ALG13-CDG have been hindered by the lack of observable glycosylation defects in patient samples, particularly in blood and fibroblasts. However, the profound neurological symptoms associated with ALG13-CDG strongly suggest a primary impact on the brain. To test this hypothesis, we established a brain model of ALG13-CDG using induced pluripotent stem cells derived from fibroblasts, which were subsequently differentiated into human cortical cortical organoids(hCOs). Contrary to previous reports of random X-inactivation in individuals with ALG13-CDG, we observed X-inactivation skewing within ALG13-CDG cell lines. Our multi-omics approach, encompassing single-cell RNA-seq, proteomics, glycoproteomic, and metabolomics analyses, revealed significant reductions in glycosylation and expression of key proteins essential for axon growth, neuronal migration, and synaptic plasticity. Additionally, alterations in protein abundances associated with neuronal migration and nucleotide synthesis were also observed, along with distinctive changes in genes linked to epilepsy risk and lipid metabolism. Metabolomic analyses ALG13-CDG hCOs showed elevated GlcNAc levels and decreased nucleotide synthesis metabolites. Importantly, our study sheds light on the previously unrecognized protein glycosylation defect in ALG13-CDG, offering valuable insights into the brain-related disturbances underlying the disease pathology. Furthermore, our findings hold promise for guiding the clinical management of seizures in ALG13-CDG patients, addressing a critical unmet medical need.

ORGANISM(S): Homo sapiens

PROVIDER: GSE266155 | GEO | 2025/12/31

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:Glycosylation of proteins is an important post-translational modification that comprises two major stages: synthesis and attachment of glycans in the endoplasmic reticulum (ER), and glycan remodeling in the ER and Golgi apparatus (GA). Genetic disorders impairing a step of this process give rise to a group of pathologies named congenital disorders of glycosylation (CDG). The most common CDG type is PMM2-CDG, caused by mutations on PMM2 (phosphomannomutase 2) genes. PMM2-CDG clinical presentation vary among affected individuals. CDG condition is considered a form of chronic ER stress. Inhibition of glycosylation results in the accumulation of misfolded proteins in the ER, which induces a complex protective reaction known as the unfolded protein response (UPR), which includes translational repression, transcriptional activation of ER chaperones, and ER-associated degradation of unfolded proteins. In search for CDG biomarkers, EBV-transformed CDG B-lymphoblastoid cell lines (B-LCL) were used as cellular models due to two main advantages: first, B-LCL are secretory cells that are forced to continuously synthetize proteins such as immunoglobulins, cytokines or other cell to cell communication molecules, so their ER is chronically stressed; second, as immune system cells, they express common genes and share common regulatory mechanisms with nervous system cells such as neurons (affected cell in most CDG patients). In this work we generated a collection of 7 EBV-transformed PMM2-CDG B-LCL by culture of patients' purified blood B lymphocytes with supernatants of the marmoset EBV-leukocyte cell line B95-8, and compared their transcriptome with that of 7 EBV-transformed healthy B-LCL. Our analysis revealed 348 significantly up-regulated and 106 down-regulated protein-coding genes compared to non-CDG cell lines, which included response to stress, transcription factors, glycosylation, motility and cell junction, development and cell (neuron) differentiation and synapse genes. Gene Set Enrichment Analysis (GSEA) identified biological consequences associated to gene expression changes in PMM2-CDG cells related to the unfolded protein response (UPR), RNA metabolism and the endoplasmic reticulum, Golgi apparatus and mitochondria components. Dysregulated important genes were MAN1A1, MGAT2, CHST4, LARGE, ADAM23, SEMA4D, UNC13C, AUTS2, CA2, SMN1, EXOSC2 expressed not only in the immune system but in other tissues including the nervous system that were compatible with CDG pathophysiology. Our results confirm PMM2-CDG EBV-transformed B-LCL as a suitable cell model that expands both our knowledge and tools to study CDG pathology at the cellular level, useful for functional characteristics and potential therapeutic drugs testing.

Project description:Glycosylation is the most common post-translational modification of proteins, yet genes relevant to the synthesis of glycan structure and function are incompletely represented and poorly annotated on the commercially available arrays. To fill the need for expression analysis of such genes we employed the Affymetrix technology to develop a focused and highly annotated glycogene chip representing human and murine glycogenes, including glycosyltranferases, nucleotide sugar transporters, glycosidases, proteoglycans and glycan-binding proteins. In this report the array has been used to generate glycogene expression profiles of nine murine tissues. Global analysis with a hierarchical clustering algorithm, reveals that expression profiles in immune tissues (thymus, spleen, lymph node and bone marrow) are more closely related, relative to those of non-immune tissues (kidney, liver, brain and testes). Of the biosynthetic enzymes, those responsible for synthesis of the core regions of N-and O-linked oligosaccharides are ubiquitously expressed, while glycosyltransferase that elaborate terminal structures are expressed in a highly tissue-specific manner, accounting for tissue and ultimately cell type-specific glycosylation. Comparison of gene expression profiles with MALDI-TOF profiling of N-linked oligosaccharides suggested that the alpha-1-3 fucosyltransferase IX, Fut9, is the enzyme responsible for terminal fucosylation in kidney and brain, a finding validated by analysis of Fut9 knockout mice. Two families of glycan-binding proteins, C-type lectins and siglecs, are predominately expressed in the immune tissues, consistent with their emerging functions in both innate and acquired immunity. The glycogene chip reported in this study is available to the scientific community through the Consortium for Functional Glycomics (http://www.functionalglycomics.org). Keywords: Glycogenes, Glycomics, Glycosyltransferase, Lectin, Glycosylation, Glycome, Microarray, Kidney, Fut9

Dataset Information

Deciphering the Neurological Puzzle in ALG13-CDG Through Cutting-Edge Brain Organoid Modeling.

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets