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:Disruption of N-linked glycosylation has a broad impact on proper glycosylation of nascent glycoproteins in the endoplasmic reticulum, which affect multiple signalling pathways( by changing the stability of membrane proteins or the signalling ability of membrane receptors) and may be responsible of the fibrotic stage associated to CDG type-I. We used microarrays to characterize the global changes in gene expression in three distinct groups of CDG-I patients and we identified a common perturbation in the expression of genes encoding for proteins involved in the stress as well as in the fibrotic responses. Experiment Overall Design: Primary fibroblasts, obtained from forearm skin biopsies of healthy control subjects and three distinct groups of CDG-I patients, were cultured in F12 DMEM supplemented with 4.5 g/l glucose and 10% fetal calf serum prior to RNA extraction and Hybridization on human HG 133 A Affymetrix Microarrays. To avoid bias related to the analysis of a specific CDG-I type or to a specific individual expression pattern, we have considered three patients for the CDG-Ic and -Ie group and two patients for the CDG-Ig group. Moreover the total RNA was extracted from three different independent biological replicates.
Project description:In this project, CSF samples from healthy volunteers and patients diagnosed with congenital disorders of glycosylation (CDG) were analyzed with MS-based glycoproteomics to characterize the glycoproteome in the two cohorts. In order to identify highly truncated glycopeptides and glycopeptides that show the complete loss of glycosylation, we chose to not perform a glycopeptide enrichment. Using the high identification rate of the timsTOF Pro including PASEF fragmentation, we were able to detect over 800 unique glycopeptides. We show that changes in protein N-glycosylation of CDG patients can be different on brain-derived proteins compared to blood derived proteins.
Project description:Disruption of N-linked glycosylation has a broad impact on proper glycosylation of nascent glycoproteins in the endoplasmic reticulum, which affect multiple signalling pathways( by changing the stability of membrane proteins or the signalling ability of membrane receptors) and may be responsible of the fibrotic stage associated to CDG type-I. We used microarrays to characterize the global changes in gene expression in three distinct groups of CDG-I patients and we identified a common perturbation in the expression of genes encoding for proteins involved in the stress as well as in the fibrotic responses. Keywords: disease state analysis
Project description:In the biological systems, several genes are involved in protein glycosylation pathway. Congenital Disorders of Glycosylation (CDG) is known to be a multisystem disorder. Pathogenic variants in the glycosylation genes lead to abnormal N- or O-linked glycosylation that causes cellular stress. We used TMT-based N-glycoproteomics and proteomics on different patient-derived CDG and control fibroblasts to characterize the alteration in glycoproteome and proteome. 12 fractions of enriched glycopeptides after size exclusion chromatography (SEC) and 12 fractions after basic reverse phase liquid chromatography (bRPLC) were analyzed by LC-MS/MS for glycoproteomics and proteomics, respectively. A site-specific aberrant glycosylation was observed for several proteins such as mitochondrial, autophagy, extracellular matrix and cell adhesion proteins. By using quantitative proteomics, we observed alteration in abundances of several proteins separated the affected individuals and controls. The glycoproteomics and proteomics analysis in CDG patients provides the potential biomarkers and will increase our general understanding of its pathogenesis.
Project description:PMM2-CDG is a rare inborn error of metabolism caused by deficiency of the phosphomannomutase-2 (PMM2) enzyme, which leads to impaired protein glycosylation. While the disorder presents with primarily neurological symptoms, there is limited knowledge about the specific brain-related changes that result from PMM2 deficiency. We found aberrant neural activity in 2D neuronal networks from individuals with PMM2-CDG. Utilizing multi-omics datasets from 3D brain organoids derived from individuals with PMM2-CDG, we found widespread decreases in protein glycosylation, highlighting impaired glycosylation as a key pathological feature of PMM2-CDG. Furthermore, we identified impaired mitochondrial structure and abnormal glucose metabolism in PMM2-CDG brain organoids, indicating disturbances in energy metabolism. Correlation between PMM2 enzymatic activity in brain organoids and symptom severity suggests that the level of PMM2 enzyme function directly influences neurological manifestations. These findings enhance our understanding of specific brain-related perturbations associated with PMM2-CDG, offering insights into the underlying mechanisms and potential directions for therapeutic interventions.
Project description:Nucleotide sugar transporters (NSTs) are ER and Golgi-resident members of the solute carrier 35 (SLC35) family which supply substrates for glycosylation by exchanging lumenal nucleotide monophosphates for cytosolic nucleotide sugars. Defective NSTs have been associated with congenital disorders of glycosylation (CDG), however, molecular basis of many types of CDG remains poorly characterized. To better understand CDG biology, we identified potential interaction partners of UDP-galactose transporter (SLC35A2), UDP-N-acetylglucosamine transporter (SLC35A3) and an orphan nucleotide sugar transporter SLC35A4. For this purpose, each of the SLC35A2-A4 proteins was used as a bait in four independent pull-down experiments and the identity of the immunoprecipitated material was discovered using MS techniques. The consensus findings for each of the NSTs tested were listed as potential interaction partners and should prove useful as a starting point for deciphering the NST interaction network.
Project description:Phosphomannomutase 2 (PMM2) converts mannose-6-phospahate to mannose-1-phosphate; the substrate for GDP-mannose, a building block of the glycosylation biosynthetic pathway. Pathogenic variants in the PMM2 gene have been shown to be associated with protein hypoglycosylation causing PMM2-congenital disorder of glycosylation (PMM2-CDG). While mannose supplementation improves glycosylation in vitro, but not in vivo, we hypothesized that liposomal delivery of mannose-1-phosphate could increase the stability and delivery of the activated sugar to enter the targeted compartments of cells. Thus, we studied the effect of liposome-encapsulated mannose-1-P (GLM101) on global protein glycosylation and on the cellular proteome in skin fibroblasts from individuals with PMM2-CDG, as well as in individuals with two N-glycosylation defects early in the pathway, namely ALG2-CDG and ALG11-CDG. We leveraged multiplexed proteomics and N-glycoproteomics in fibroblasts derived from different individuals with various pathogenic variants in PMM2, ALG2 and ALG11 genes. Proteomics data revealed a moderate but significant change in the abundance of some of the proteins in all CDG fibroblasts upon GLM101 treatment. On the other hand, N-glycoproteomics revealed the GLM101 treatment enhanced the expression levels of several high-mannose and complex/hybrid glycopeptides from numerous cellular proteins in individuals with defects in PMM2 and ALG2 genes. Both PMM2-CDG and ALG2-CDG exhibited several-fold increase in glycopeptides bearing Man6 and higher glycans and a decrease in Man5 and smaller glycan moieties, suggesting that GLM101 helps in the formation of mature glycoforms. These changes in protein glycosylation were observed in all individuals irrespective of their genetic variants. ALG11-CDG fibroblasts also showed increase in high mannose glycopeptides upon treatment; however, the improvement was not as dramatic as the other two CDG. Overall, our findings suggest that treatment with GLM101 overcomes the genetic block in the glycosylation pathway and can be used as a potential therapy for CDG with enzymatic defects in early steps in protein N-glycosylation.
Project description:PGM1 deficiency is recognized as the third most common N-linked Congenital Disorders of Glycosylation (CDG) in humans. Affected individuals present with liver, musculoskeletal, endocrine, and coagulation symptoms; however, the most life-threatening complication is an early onset of dilated cardiomyopathy (DCM). Recently, we discovered that oral D-galactose supplementation improved liver disease, endocrine and coagulation abnormalities, but does not alleviate the fatal cardiomyopathy and the associated myopathy. To study the pathobiology of the cardiac disease observed in PGM1-CDG, we constructed a novel cardiomyocyte-specific conditional Pgm2 (mouse ortholog of human PGM1) knockout (Pgm2 cKO) mouse model. Echocardiography studies corroborated a DCM phenotype with significantly reduced ejection fraction and left ventricular dilatation similar to those seen in individuals with PGM1-CDG. Histological studies demonstrated excess glycogen accumulation and fibrosis, while ultrastructural analysis revealed Z-disk disarray and swollen/fragmented mitochondria. We observed similar ultrastructural pathology in the cardiac explant of an individual with PGM1-CDG. We found decreased mitochondrial function in the heart of Pgm2 cKO mice. Transcriptomic analysis of hearts from Pgm2 cKO mice demonstrated a gene signature of DCM. Although proteomics revealed only mild changes in global protein expression in left ventricular tissue of Pgm2 cKO mice, a glycoproteomic analysis revealed an overall decreased protein glycosylation with significant glycosylation defects in sarcolemmal proteins including different subunits of laminin protein. Finally, augmentation of PGM1 in KO mice via AAV9-PGM1 gene replacement therapy prevented and halted the progression of the DCM phenotype.
Project description:Transcriptional profiling of Homo sapiens inflammatory skin diseases (whole skin biospies): Psoriasis (Pso), vs Atopic Dermatitis (AD) vs Lichen planus (Li), vs Contact Eczema (KE), vs Healthy control (KO) In recent years, different genes and proteins have been highlighted as potential biomarkers for psoriasis, one of the most common inflammatory skin diseases worldwide. However, most of these markers are not psoriasis-specific but also found in other inflammatory disorders. We performed an unsupervised cluster analysis of gene expression profiles in 150 psoriasis patients and other inflammatory skin diseases (atopic dermatitis, lichen planus, contact eczema, and healthy controls). We identified a cluster of IL-17/TNFα-associated genes specifically expressed in psoriasis, among which IL-36γ was the most outstanding marker. In subsequent immunohistological analyses IL-36γ was confirmed to be expressed in psoriasis lesions only. IL-36γ peripheral blood serum levels were found to be closely associated with disease activity, and they decreased after anti-TNFα-treatment. Furthermore, IL-36γ immunohistochemistry was found to be a helpful marker in the histological differential diagnosis between psoriasis and eczema in diagnostically challenging cases. These features highlight IL-36γ as a valuable biomarker in psoriasis patients, both for diagnostic purposes and measurement of disease activity during the clinical course. Furthermore, IL-36γ might also provide a future drug target, due to its potential amplifier role in TNFα- and IL-17 pathways in psoriatic skin inflammation. In recent years, different genes and proteins have been highlighted as potential biomarkers for psoriasis, one of the most common inflammatory skin diseases worldwide. However, most of these markers are not psoriasis-specific but also found in other inflammatory disorders. We performed an unsupervised cluster analysis of gene expression profiles in 150 psoriasis patients and other inflammatory skin diseases (atopic dermatitis, lichen planus, contact eczema, and healthy controls). We identified a cluster of IL-17/TNFα-associated genes specifically expressed in psoriasis, among which IL-36γ was the most outstanding marker. In subsequent immunohistological analyses IL-36γ was confirmed to be expressed in psoriasis lesions only. IL-36γ peripheral blood serum levels were found to be closely associated with disease activity, and they decreased after anti-TNFα-treatment. Furthermore, IL-36γ immunohistochemistry was found to be a helpful marker in the histological differential diagnosis between psoriasis and eczema in diagnostically challenging cases. These features highlight IL-36γ as a valuable biomarker in psoriasis patients, both for diagnostic purposes and measurement of disease activity during the clinical course. Furthermore, IL-36γ might also provide a future drug target, due to its potential amplifier role in TNFα- and IL-17 pathways in psoriatic skin inflammation.