Secondary deficiency of neuraminidase 1 contributes to CNS pathology in neurological mucopolysaccharidoses via hypersialylation of brain glycoproteins.

Mucopolysaccharidoses (MPS) are lysosomal storage diseases caused by defects in catabolism of glycosaminoglycans. MPS I, II, III and VII are associated with lysosomal accumulation of heparan sulphate and manifest with neurological deterioration. Most of these neurological MPS currently lack effective treatments.

CSF N-Glycomics Using High-Throughput UPLC-ESI Techniques in Alzheimer's Disease.

In this chapter, we will present a high-throughput method applied in our laboratory for the structural elucidation of the cerebrospinal fluid (CSF) N-glycome. This methodology is based on a commercial equipment developed by WATERS™ to speed up N-deglycosylation and N-glycan labeling of glycoproteins of pharmaceutical and biological interest such as monoclonal antibodies. This analytical kit is sold under the trade name of RapiFluor-MS (RFMS).

Severe kidney dysfunction in sialidosis mice reveals an essential role for neuraminidase 1 in reabsorption.

Sialidosis is an ultra-rare multisystemic lysosomal disease caused by mutations in the neuraminidase 1 (NEU1) gene. The severe type II form of the disease manifests with a prenatal/infantile or juvenile onset, bone abnormalities, severe neuropathology, and visceromegaly. A subset of these patients present with nephrosialidosis, characterized by abrupt onset of fulminant glomerular nephropathy.

-acetylneuraminate pyruvate lyase controls sialylation of muscle glycoproteins essential for muscle regeneration and function.

Deleterious variants in acetylneuraminate pyruvate lyase (NPL) cause skeletal myopathy and cardiac edema in humans and zebrafish, but its physiological role remains unknown. We report generation of mouse models of the disease: , carrying the human p.Arg63Cys variant, and with a 116-bp exonic deletion.

Higher frequency of TMEM199-CDG in the southern mediterranean area is associated with c.92G>C (p.Arg31Pro) mutation.

Congenital disorders of glycosylation (CDG) are genetic multisystem diseases, characterized by defective glycoconjugate synthesis. A small number of CDG with isolated liver damage have been described, such as TMEM199-CDG, a non-encephalopathic liver disorder with Wilson disease-like phenotype. Only eight patients with TMEM199-CDG have been described including seven Europeans (originating from Greece and Italy) and one Chinese.

Phenotypic and genetic spectrum of ATP6V1A encephalopathy: a disorder of lysosomal homeostasis.

Vacuolar-type H+-ATPase (V-ATPase) is a multimeric complex present in a variety of cellular membranes that acts as an ATP-dependent proton pump and plays a key role in pH homeostasis and intracellular signalling pathways. In humans, 22 autosomal genes encode for a redundant set of subunits allowing the composition of diverse V-ATPase complexes with specific properties and expression. Sixteen subunits have been linked to human disease.

CAMLG-CDG: a novel congenital disorder of glycosylation linked to defective membrane trafficking.

The transmembrane domain recognition complex (TRC) pathway is required for the insertion of C-terminal tail-anchored (TA) proteins into the lipid bilayer of specific intracellular organelles such as the endoplasmic reticulum (ER) membrane. In order to facilitate correct insertion, the recognition complex (consisting of BAG6, GET4 and UBL4A) must first bind to TA proteins and then to GET3 (TRC40, ASNA1), which chaperones the protein to the ER membrane. Subsequently, GET1 (WRB) and CAML form a receptor that enables integration of the TA protein within the lipid bilayer.

COG6-CDG: Novel variants and novel malformation.

Background: Deficiency of Conserved Oligomeric Golgi (COG) subunits (COG1-8) is characterized by both N- and O-protein glycosylation defects associated with destabilization and mislocalization of Golgi glycosylation machinery components (COG-CDG). Patients with COG defects present with neurological and multisystem involvement and possible malformation occurrence. Eighteen patients with COG6-CDG (COG6 mutations) were reported to date.

N-Glycomics of Human Erythrocytes.

Glycosylation is a complex post-translational modification that conveys functional diversity to glycoconjugates. Cell surface glycosylation mediates several biological activities such as induction of the intracellular signaling pathway and pathogen recognition. Red blood cell (RBC) membrane N-glycans determine blood type and influence cell lifespan.

Aberrant sialylation in a patient with a variant and liver adenomatosis.

Glycosylation is a fundamental post-translational modification of proteins that boosts their structural diversity providing subtle and specialized biological properties and functions. All those genetic diseases due to a defective glycan biosynthesis and attachment to the nascent glycoproteins fall within the wide area of congenital disorders of glycosylation (CDG), mostly causing multisystem involvement. In the present paper, we detailed the unique serum N-glycosylation of a CDG-candidate patient with an unexplained neurological phenotype and liver adenomatosis harboring a recurrent pathogenic variant.

SLC37A4-CDG: Second patient.

Recently, a disorder caused by the heterozygous de novo c.1267C>T (p.R423*) substitution in has been described.

Clinical and radiological correlates of activities of daily living in cerebellar atrophy caused by PMM2 mutations (PMM2-CDG).

We aimed to identify clinical, molecular and radiological correlates of activities of daily living (ADL) in patients with cerebellar atrophy caused by PMM2 mutations (PMM2-CDG), the most frequent congenital disorder of glycosylation. Twenty-six PMM2-CDG patients (12 males; mean age 13 ± 11.1 years) underwent a standardized assessment to measure ADL, ataxia (brief ataxia rating scale, BARS) and phenotype severity (Nijmegen CDG rating scale, NCRS).

Tear N-glycomics in vernal and atopic keratoconjunctivitis.

Purpose: Tear fluid N-Glycome from patients affected with vernal (VKC) and atopic keratoconjunctivitis (AKC) was investigated to identify specific changes in tears and to recognize possible glyco-biomarkers.

Methods: The analysis of the N-glycans was performed using matrix-assisted laser desorption ionization mass spectrometry on single tear samples. Tears from control normal subjects (CTRL), VKC and AKC patients were processed and treated with peptide N-glycosidase F (PNGase F) to deglycosylate N-glycoproteins.

Lipopolysaccharide from Gut-Associated Lymphoid-Tissue-Resident Alcaligenes faecalis: Complete Structure Determination and Chemical Synthesis of Its Lipid A.

Alcaligenes faecalis is the predominant Gram-negative bacterium inhabiting gut-associated lymphoid tissues, Peyer's patches. We previously reported that an A. faecalis lipopolysaccharide (LPS) acted as a weak agonist for Toll-like receptor 4 (TLR4)/myeloid differentiation factor-2 (MD-2) receptor as well as a potent inducer of IgA without excessive inflammation, thus suggesting that A.

HILIC-UPLC-MS for high throughput and isomeric N-glycan separation and characterization in Congenital Disorders Glycosylation and human diseases.

N-glycan analyses may serve uncovering disease-associated biomarkers, as well as for profiling distinctive changes supporting diagnosis of genetic disorders of glycan biosynthesis named congenital disorders of glycosylation (CDG). Strategies based on liquid chromatography (LC) preferentially coupled to electrospray ionization (ESI) - mass spectrometry (MS) have emerged as powerful analytical methods for N-glycan identification and characterization. To enhance detection sensitivity, glycans are commonly labelled with a functional tag prior to LC-MS analysis.

Structure of the unusual HH103 lipopolysaccharide and its role in symbiosis.

Rhizobia are soil bacteria that form important symbiotic associations with legumes, and rhizobial surface polysaccharides, such as K-antigen polysaccharide (KPS) and lipopolysaccharide (LPS), might be important for symbiosis. Previously, we obtained a mutant of HH103, , that does not produce KPS, a homopolysaccharide of a pseudaminic acid derivative, but whose LPS electrophoretic profile was indistinguishable from that of the WT strain. We also previously demonstrated that the HH103 operon is responsible for 5-acetamido-3,5,7,9-tetradeoxy-7-(3-hydroxybutyramido)-l--l--nonulosonic acid [Pse5NAc7(3OHBu)] production and is involved in HH103 KPS and LPS biosynthesis and that an HH103 mutant cannot produce KPS and displays an altered LPS structure.

ALG12-CDG: novel glycophenotype insights endorse the molecular defect.

Congenital disorders of glycosylation (CDG) are genetic diseases characterized by deficient synthesis (CDG type I) and/or abnormal processing (CDG type II) of glycan moieties linked to protein and lipids. The impact of the molecular defects on protein glycosylation and in turn on the clinical phenotypes of patients with CDG is not yet understood. ALG12-CDG is due to deficiency of ALG12 α1,6-mannosyltransferase that adds the eighth mannose residue on the dolichol-PP-oligosaccharide precursor in the endoplasmic reticulum.

CSF N-Glycoproteomics Using MALDI MS Techniques in Neurodegenerative Diseases.

CSF diagnostics has proved to be a formidable testing ground for N-glycoproteomic analysis of neurological diseases. To characterize specific N-glycan profiles of CSF in early and advanced phases of Alzheimer's disease, as well as in lysosomal storage disorders such as Tay-Sachs disease, we set up in our lab a robust and feasible protocol by coupling bioanalytical methods and mass spectrometry analysis.Starting from a few microliters of CSF, after protein denaturation, reduction, and alkylation, N-glycans are released from glycoproteins using the peptide-N-glycosidase F (PNGase F) and purified.

Characterization of the Salmonella Typhimurium core oligosaccharide and its reducing end 3-deoxy-d-manno-oct-2-ulosonic acid used for conjugate vaccine production.

One of the strategies adopted for the development of a bivalent conjugate vaccine against invasive nontyphoidal Salmonella consists of linking the O-antigen component of S. Typhimurium and S. Entertidis lipopolysaccharides to the carrier protein CRM, a non-toxic variant of diphtheria toxin.

SLC35A2-CDG: Functional characterization, expanded molecular, clinical, and biochemical phenotypes of 30 unreported Individuals.

Pathogenic de novo variants in the X-linked gene SLC35A2 encoding the major Golgi-localized UDP-galactose transporter required for proper protein and lipid glycosylation cause a rare type of congenital disorder of glycosylation known as SLC35A2-congenital disorders of glycosylation (CDG; formerly CDG-IIm). To date, 29 unique de novo variants from 32 unrelated individuals have been described in the literature. The majority of affected individuals are primarily characterized by varying degrees of neurological impairments with or without skeletal abnormalities.

The -glycan structures of the antigenic variants of chlorovirus PBCV-1 major capsid protein help to identify the virus-encoded glycosyltransferases.

The chlorovirus chlorella virus 1 (PBCV-1) is a large dsDNA virus that infects the microalga NC64A. Unlike most other viruses, PBCV-1 encodes most, if not all, of the machinery required to glycosylate its major capsid protein (MCP). The structures of the four -linked glycans from the PBCV-1 MCP consist of nonasaccharides, and similar glycans are not found elsewhere in the three domains of life.