Publications by authors named "Luisa Sturiale"

66 Publications

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

iScience 2021 Apr 18;24(4):102323. Epub 2021 Mar 18.

CNR, Institute for Polymers, Composites and Biomaterials, IPCB, 95126 Catania, Italy.

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. Serum transferrin isoelectric focusing showed a surprising N-glycosylation pattern consisting on hyposialylation, as well as remarkable hypersialylation. Mass spectrometry-based glycomic analyses of individual serum glycoproteins enabled to unveil hypersialylated complex N-glycans comprising up to two sialic acids per antenna. Further advanced MS analysis showed the additional sialic acid is bonded through an α2-6 linkage to the peripheral N-acetylglucosamine residue.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.isci.2021.102323DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8050382PMC
April 2021

SLC37A4-CDG: Second patient.

JIMD Rep 2021 Mar 6;58(1):122-128. Epub 2021 Jan 6.

Department of Pediatrics Center for Metabolic Diseases, University Hospitals Leuven Leuven Belgium.

Recently, a disorder caused by the heterozygous de novo c.1267C>T (p.R423*) substitution in has been described. This causes mislocalization of the glucose-6-phosphate transporter to the Golgi leading to a congenital disorder of glycosylation type II (SLC37A4-CDG). Only one patient has been reported showing liver disease that improved with age and mild dysmorphism. Here we report the second patient with a type II CDG caused by the same heterozygous de novo c.1267C>T (p.R423*) mutation thereby confirming the pathogenicity of this variant and expanding the clinical picture with type 1 diabetes, severe scoliosis, and membranoproliferative glomerulonephritis. Additional clinical and biochemical data provide further insight into the mechanism and prognosis of SLC37A4-CDG.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jmd2.12195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7932867PMC
March 2021

Mass spectrometry glycophenotype characterization of ALG2-CDG in Argentinean patients with a new genetic variant in homozygosis.

Glycoconj J 2021 Apr 1;38(2):191-200. Epub 2021 Mar 1.

Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Santísima Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, X5014AKN, Córdoba, Argentina.

Human ALG2 encodes an α 1,3mannosyltransferase that catalyzes the first steps in the synthesis of N-glycans in the endoplasmic reticulum. Variants in ALG2cause a congenital disorder of glycosylation (CDG) known as ALG2-CDG. Up to date, nine ALG2-CDG patients have been reported worldwide. ALG2-CDG is a rare autosomal recessive inherited disorder characterized by neurological involvement, convulsive syndrome of unknown origin, axial hypotonia, and mental and motor regression. In this study, we used MALDI-TOF MS to define both total serum protein and transferrin (Tf) N-glycan phenotypes in three ALG2-CDG patients carrying a c.752G > T, p.Arg251Leu ALG2 missense variant in homozygous state, as determined by exome sequencing. Comparing it to control samples, we have observed Tf under-occupancy of glycosylation site(s) typical of a defective N-glycan assembly and the occurrence of oligomannose and hybrid type N-glycans. Moreover, we have observed a slight oligomannose accumulation in total serum glyco-profiles. The increased heterogeneity of serum N-glycome in the studied patients suggests a marginal disarrangement of the glycan processing in ALG2-CDG. Previous studies reported on slightly increased concentrations of abnormal serum N-glycans in CDG-I due to defects in the mannosylation steps of dolichol-linked oligosaccharide biosynthesis. This preliminary work aims at considering serum N-glycan accumulation of high mannosylated glycoforms, such as oligomannose and hybrid type N-glycans, as potential diagnostic signals for ALG2-CDG patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10719-021-09976-wDOI Listing
April 2021

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

Cerebellum 2021 Feb 22. Epub 2021 Feb 22.

Child Neurology and Psychiatry Section, Department of Clinical and Experimental Medicine, University of Catania, Policlinico, Via Santa Sofia 78, 95123, Catania, Italy.

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). MRI biometry of the cerebellum and the brainstem were performed in 23 patients (11 males; aged 5 months-18 years) and 19 control subjects with equal gender and age distributions. The average total ADL score was 15.3 ± 8.5 (range 3-32 out of 36 indicating severe functional disability), representing variable functional outcome in PMM2-CDG patients. Total ADL scores were significantly correlated with NCRS (r = 0.55, p < 0.001) and BARS scores (r = 0.764; p < 0.001). Severe intellectual disability, peripheral neuropathy, and severe PMM2 variants were all significantly associated with worse functional outcome. Higher ADL scores were significantly associated with decreased diameters of cerebellar vermis (r = 0.347; p = 0.004), hemispheres (r = 0.436; p = 0.005), and brainstem, particularly the mid-pons (r = 0.64; p < 0.001) representing the major radiological predictor of functional disability score in multivariate regression analysis. We show that cerebellar syndrome severity, cognitive level, peripheral neuropathy, and genotype correlate with ADL used to quantify disease-related deficits in PMM2-CDG. Brainstem involvement should be regarded among functional outcome predictors in patients with cerebellar atrophy caused by PMM2-CDG.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s12311-021-01242-xDOI Listing
February 2021

Tear N-glycomics in vernal and atopic keratoconjunctivitis.

Allergy 2021 Feb 14. Epub 2021 Feb 14.

Department of Neuroscience, Ophthalmology Unit, University of Padua, Padua, Italy.

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. Released N-glycans were purified, permethylated, and analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry and tandem mass spectrometry (MALDI-TOF MS and MALDI-TOF MS/MS).

Results: More than 150 complex N-glycans, including highly fucosylated biantennary, triantennary, tetra-antennary, and bisecting species, were observed in our spectra. Three distinct patterns for CTRL, VKC, and AKC patients were identified in terms of relative intensities for some N-glycans structures. Major variations involved bisecting and hyperfucosylated glycoforms. The most intense ions were associated with species at m/z 1907.0 (asialo, agalacto, bisected, biantennary structure-NGA2B) in CTRL MS profiles, at m/z 2605.3 and 2966.5 in VKC, and at m/z 2792.4 in AKC corresponding to a well-known biantennary, disialylated N-glycan. Several peaks were associated with structures bearing one or two Lewis X epitopes. Structures were confirmed by MS/MS analysis. Quantitative differences among the three groups were statistically significant.

Conclusions: Tear MS profiles are rich in specific glycoforms, particularly those with a high fucosylation degree, indicating both core and peripheral decoration. Tear N-glycome analysis provided important information for a better comprehension of VKC and AKC alterations at the molecular level.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/all.14775DOI Listing
February 2021

SLC35A2-CDG: Novel variant and review.

Mol Genet Metab Rep 2021 Mar 30;26:100717. Epub 2021 Jan 30.

Unit for Multidisciplinary Research in Biomedicine, ICBAS, UP, Porto, Portugal.

encodes the X-linked transporter that carries uridine diphosphate (UDP)-galactose from the cytosol to the lumen of the Golgi apparatus and the endoplasmic reticulum. Pathogenic variants have been associated to a congenital disorder of glycosylation (CDG) with epileptic encephalopathy as a predominant feature. Among the sixty five patients described so far, a strong gender bias is observed as only seven patients are males. This work is a review and reports a SLC35A2-CDG in a male without epilepsy and with growth deficiency associated with decreased serum IGF1, minor neurological involvement, minor facial dysmorphism, and camptodactyly of fingers and toes. Sequence analysis revealed a hemizygosity for a novel variant: c.233A > G (p.Lys78Arg) in SLC35A2. Further analysis of SLC35A2 sequence by comparing both orthologous and paralogous positions, revealed that not only the variant found in this study, but also most of the reported mutated positions are conserved in SLC35A2 orthologous, and many even in the paralogous SLC35A1 and SLC35A3. This is strong evidence that replacements at these positions will have a critical pathological effect and may also explain the gender bias observed among SLC35A2-CDG patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ymgmr.2021.100717DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7851840PMC
March 2021

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

Angew Chem Int Ed Engl 2021 04 22;60(18):10023-10031. Epub 2021 Mar 22.

Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.

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. faecalis LPS might be used as a safe adjuvant. In this study, we characterized the structure of both the lipooligosaccharide (LOS) and LPS from A. faecalis. We synthesized three lipid A molecules with different degrees of acylation by an efficient route involving the simultaneous introduction of 1- and 4'-phosphates. Hexaacylated A. faecalis lipid A showed moderate agonistic activity towards TLR4-mediated signaling and the ability to elicit a discrete interleukin-6 release in human cell lines and mice. It was thus found to be the active principle of the LOS/LPS and a promising vaccine adjuvant candidate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.202012374DOI Listing
April 2021

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

Glycoconj J 2021 Apr 11;38(2):201-211. Epub 2020 Sep 11.

CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy.

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. Since most derivatization techniques are notoriously time-consuming, some commercial analytical kits have been developed to speed up N-deglycosylation and N-glycan labelling of glycoproteins of pharmaceutical and biological interest such as monoclonal antibodies (mAbs). We exploited the analytical capabilities of RapiFluor-MS (RFMS) to perform, by a slightly modified protocol, a detailed N-glycan characterization of total serum and single serum glycoproteins from specific patients with CDG (MAN1B1-CDG, ALG12-CDG, MOGS-CDG, TMEM199-CDG). This strategy, accomplished by Hydrophilic Interaction Chromatography (HILIC)-UPLC-ESI-MS separation of the RFMS derivatized N-glycans, allowed us to uncover structural details of patients serum released N-glycans, thus extending the current knowledge on glycan profiles in these individual glycosylation diseases. The applied methodology enabled to differentiate in some cases either structural isomers and isomers differing in the linkage type. All the here reported applications demonstrated that RFMS method, coupled to HILIC-UPLC-ESI-MS, represents a sensitive high throughput approach for serum N-glycome analysis and a valuable option for glycan detection and separation particularly for isomeric species.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10719-020-09947-7DOI Listing
April 2021

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

Glycoconj J 2019 12 16;36(6):461-472. Epub 2019 Sep 16.

CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy.

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. ALG12-CDG is a severe multisystem disease associated with low to deficient serum immunoglobulins and recurrent infections. We thoroughly investigated the glycophenotype in a patient with novel ALG12 variants and immunodeficiency. We analyzed serum native transferrin, as first line test for CDG and we profiled serum IgG and total serum N-glycans by a combination of consolidated (N-glycan analysis by MALDI MS) and innovative mass spectrometry-based protocols, such as GlycoWorks RapiFluor N-glycan analysis coupled with LC-ESI MS. Intact serum transferrin showed, as expected for a CDG type I defect, underoccupancy of N-glycosylation sites. Surprisingly, total serum proteins and IgG N-glycans showed some specific changes, consisting in accumulating amounts of definite high-mannose and hybrid structures. As a whole, ALG12-CDG behaves as a dual CDG (CDG-I and II defects) and it is associated with distinct, abnormal glycosylation of total serum and IgG N-glycans. Glycan profiling of target glycoproteins may endorse the molecular defect unraveling the complex clinical phenotype of CDG patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10719-019-09890-2DOI Listing
December 2019

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

Methods Mol Biol 2019 ;2044:255-272

CNR, Istituto per i Polimeri, Compositi e i Biomateriali Catania, Catania, Italy.

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. The analysis of permethylated N-glycans by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and MALDI-TOF MS/MS allowed us to identify specific glyco-structures and also to distinguish between isobaric N-glycans.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/978-1-4939-9706-0_16DOI Listing
May 2020

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

Carbohydr Res 2019 Jul 6;481:43-51. Epub 2019 Jun 6.

Department of Life Sciences, University of Trieste, Via L. Giorgieri 1, Bdg C11, 34127, Trieste, Italy. Electronic address:

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. The conjugation reaction uses the reducing end residue 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) of the core to which the O-antigen chain is bound (OAg-core). OAg-core chains are cleaved from the lipid A directly in the fermentation broth by mild acid treatment. Kdo has been reported to undergo structural changes under these conditions and therefore the Kdo at the reducing end was thoroughly analysed to verify its structural integrity. For this purpose, low molecular mass OAg-core chains extracted from S. Typhimurium wild type bacteria and core oligosaccharides extracted from S. Typhimurium bacteria mutated not to produce O-antigen repeats were characterized by GLC-MS, MALDI-TOF-MS and NMR spectroscopy. Moreover, a combination of H-H and H-C experiments confirmed the linkage positions, sequence and structure of the octasaccharide core with 5-linked Kdo present at the reducing end in its native structure: α-GlcpNAc-(1→2)-α-Glcp-(1→2)-α-Galp-(1→3)-[α-Galp-(1→6)]-α-Glcp-(1→3)-[α-Hepp-(1→7)]-α-Hepp-(1→3)-α-Hepp-(1→5)-Kdo.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carres.2019.05.014DOI Listing
July 2019

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

Hum Mutat 2019 07 24;40(7):908-925. Epub 2019 Apr 24.

Department of Metabolic Medicine, The Royal Children's Hospital, Melbourne, Parkville, Victoria, Australia.

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. Surprisingly, most affected individuals do not show abnormalities in serum transferrin N-glycosylation, a common biomarker for most types of CDG. Here we present data characterizing 30 individuals and add 26 new variants, the single largest study involving SLC35A2-CDG. The great majority of these individuals had normal transferrin glycosylation. In addition, expanding the molecular and clinical spectrum of this rare disorder, we developed a robust and reliable biochemical assay to assess SLC35A2-dependent UDP-galactose transport activity in primary fibroblasts. Finally, we show that transport activity is directly correlated to the ratio of wild-type to mutant alleles in fibroblasts from affected individuals.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/humu.23731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6661012PMC
July 2019

Biophysical Approaches to Solve the Structures of the Complex Glycan Shield of Chloroviruses.

Adv Exp Med Biol 2018;1104:237-257

Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE, USA.

The capsid of Paramecium bursaria chlorella virus (PBCV-1) contains a heavily glycosylated major capsid protein, Vp54. The capsid protein contains four glycans, each N-linked to Asn. The glycan structures are unusual in many aspects: (1) they are attached by a β-glucose linkage, which is rare in nature; (2) they are highly branched and consist of 8-10 neutral monosaccharides; (3) all four glycoforms contain a dimethylated rhamnose as the capping residue of the main chain, a hyper-branched fucose residue and two rhamnose residues ''with opposite absolute configurations; (4) the four glycoforms differ by the nonstoichiometric presence of two monosaccharides, L-arabinose and D-mannose ; (5) the N-glycans from all of the chloroviruses have a strictly conserved core structure; and (6) these glycans do not resemble any structures previously reported in the three domains of life.The structures of these N-glycoforms remained elusive for years because initial attempts to solve their structures used tools developed for eukaryotic-like systems, which we now know are not suitable for this noncanonical glycosylation pattern. This chapter summarizes the methods used to solve the chlorovirus complex glycan structures with the hope that these methodologies can be used by scientists facing similar problems.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/978-981-13-2158-0_12DOI Listing
July 2019

Hypoacylated LPS from Foodborne Pathogen Induces Moderate TLR4-Mediated Inflammatory Response in Murine Macrophages.

Front Cell Infect Microbiol 2018 27;8:58. Epub 2018 Feb 27.

Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia.

Toll-like receptor 4 (TLR4) initiates immune response against Gram-negative bacteria upon specific recognition of lipid A moiety of lipopolysaccharide (LPS), the major component of their cell wall. Some natural differences between LPS variants in their ability to interact with TLR4 may lead to either insufficient activation that may not prevent bacterial growth, or excessive activation which may lead to septic shock. In this study we evaluated the biological activity of LPS isolated from pathogenic strain of , the most widespread bacterial cause of foodborne diarrhea in humans. With the help of hydrophobic chromatography and MALDI-TOF mass spectrometry we showed that LPS from a strain O2A consists of both hexaacyl and tetraacyl forms. Since such hypoacylation can result in a reduced immune response in humans, we assessed the activity of LPS from in mouse macrophages by measuring its capacity to activate TLR4-mediated proinflammatory cytokine and chemokine production, as well as NFκB-dependent reporter gene transcription. Our data support the hypothesis that LPS acylation correlates with its bioactivity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fcimb.2018.00058DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5835049PMC
March 2019

CSF N-Glycomics Using MALDI MS Techniques in Alzheimer's Disease.

Methods Mol Biol 2018 ;1750:75-91

CNR, Istituto per i Polimeri, Compositi e i Biomateriali Catania, Catania, Italy.

In this chapter, we present the methodology currently applied in our laboratory for the structural elucidation of the cerebrospinal fluid (CSF) N-glycome. N-glycans are released from denatured carboxymethylated glycoproteins by digestion with peptide-N-glycosidase F (PNGase F) and purified using both C18 Sep-Pak and porous graphitized carbon (PGC) HyperSep™ Hypercarb™ solid-phase extraction (SPE) cartridges. The glycan pool is subsequently permethylated to increase mass spectrometry sensitivity. Molecular assignments are performed through matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) analysis considering either the protein N-linked glycosylation pathway or MALDI TOF MS/MS data. Each stage has been optimized to obtain high-quality mass spectra in reflector mode with an optimal signal-to-noise ratio up to m/z 4800. This method has been successfully adopted to associate specific N-glycome profiles to the early and the advanced phases of Alzheimer's disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/978-1-4939-7704-8_5DOI Listing
February 2019

The Very Long Chain Fatty Acid (C:25OH) Linked to the Lipid A Is Important for the Fitness of the Photosynthetic Strain ORS278 and the Establishment of a Successful Symbiosis with Legumes.

Front Microbiol 2017 21;8:1821. Epub 2017 Sep 21.

Institut de Recherche pour le Développement, LSTM, UMR IRD, SupAgro, INRA, Université de Montpellier, CIRADMontpellier, France.

In rhizobium strains, the lipid A is modified by the addition of a very long-chain fatty acid (VLCFA) shown to play an important role in rigidification of the outer membrane, thereby facilitating their dual life cycle, outside and inside the plant. In strains, the lipid A is more complex with the presence of at least two VLCFAs, one covalently linked to a hopanoid molecule, but the importance of these modifications is not well-understood. In this study, we identified a cluster of VLCFA genes in the photosynthetic strain ORS278, which nodulates plants in a Nod factor-independent process. We tried to mutate the different genes of the VLCFA gene cluster to prevent the synthesis of the VLCFAs, but only one mutant in the gene encoding an acyltransferase was obtained. Structural analysis of the lipid A showed that LpxXL is involved in the transfer of the C:25OH VLCFA to the lipid A but not in the one of the C30:29OH VLCFA which harbors the hopanoid molecule. Despite maintaining the second VLCFA, the ability of the mutant to cope with various stresses (low pH, high temperature, high osmolarity, and antimicrobial peptides) and to establish an efficient nitrogen-fixing symbiosis was drastically reduced. In parallel, we investigated whether the BRADO0045 gene, which encodes a putative acyltransferase displaying a weak identity with the apo-lipoprotein -acyltransferase Lnt, could be involved in the transfer of the C:29OH VLCFA to the lipid A. Although the mutant exhibited phenotypes similar to the mutant, no difference in the lipid A structure was observed from that in the wild-type strain, indicating that this gene is not involved in the modification of lipid A. Our results advance our knowledge of the biosynthesis pathway and the role of VLCFAs-modified lipid A in free-living and symbiotic states of strains.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fmicb.2017.01821DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5613085PMC
September 2017

The lipopolysaccharide core oligosaccharide of plays a critical role in maintaining a proper gut symbiosis with the bean bug .

J Biol Chem 2017 11 25;292(47):19226-19237. Epub 2017 Sep 25.

the Global Research Laboratory, College of Pharmacy, Pusan National University, Busan 46241, South Korea,

Lipopolysaccharide, the outer cell-wall component of Gram-negative bacteria, has been shown to be important for symbiotic associations. We recently reported that the lipopolysaccharide O-antigen of enhances the initial colonization of the midgut of the bean bug, However, the midgut-colonizing symbionts lack the O-antigen but display the core oligosaccharide on the cell surface. In this study, we investigated the role of the core oligosaccharide, which directly interacts with the host midgut, in the symbiosis. To this end, we generated the core oligosaccharide mutant strains, Δ, Δ, Δ and Δ and determined the chemical structures of their oligosaccharides, which exhibited different compositions. The symbiotic properties of these mutant strains were compared with those of the wild-type and O-antigen-deficient Δ strains. Upon introduction into via the oral route, the core oligosaccharide mutant strains exhibited different rates of colonization of the insect midgut. The symbiont titers in fifth-instar insects revealed significantly reduced population sizes of the inner core oligosaccharide mutant strains Δ and Δ These two strains also negatively affected host growth rate and fitness. Furthermore, individuals colonized with the Δ and Δ strains were vulnerable to septic bacterial challenge, similar to insects without a symbiont. Taken together, these results suggest that the core oligosaccharide from symbionts plays a critical role in maintaining a proper symbiont population and in supporting the beneficial effects of the symbiont on its host in the symbiosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.M117.813832DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5702664PMC
November 2017

Structure of the Lipopolysaccharide from the sp. ORS285 Mutant Strain.

ChemistryOpen 2017 08 12;6(4):541-553. Epub 2017 Jun 12.

Department of Chemical Sciences University of Naples Federico II Via Cinthia 4 80126 Naples Italy.

The importance of the outer membrane and of its main constituent, lipopolysaccharide, in the symbiosis between rhizobia and leguminous host plants has been well studied. Here, the first complete structural characterization of the entire lipopolysaccharide from an O-chain-deficient ORS285 mutant is achieved by a combination of chemical analysis, NMR spectroscopy, MALDI MS and MS/MS. The lipid A structure is shown to be consistent with previously reported lipid A, that is, a heterogeneous blend of penta- to hepta-acylated species carrying a nonstoichiometric hopanoid unit and possessing very-long-chain fatty acids ranging from 26:0(25-OH) to 32:0(31-OH). The structure of the core oligosaccharide region, fully characterized for the first time here, is revealed to be a nonphosphorylated linear chain with methylated sugar residues, with a heptose residue exclusively present in the outer core region, and with the presence of two singly substituted 3-deoxy-d--oct-2-ulosonic acid (Kdo) residues, one of which is located in the outer core region. The lipid A moiety is linked to the core moiety through an uncommon 4-substituted Kdo unit.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/open.201700074DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5542761PMC
August 2017

The Lipid A from Rhodopseudomonas palustris Strain BisA53 LPS Possesses a Unique Structure and Low Immunostimulant Properties.

Chemistry 2017 Mar 22;23(15):3637-3647. Epub 2016 Dec 22.

Department of Chemical Sciences, University of Naples, Federico II, via Cinthia 4, 80126, Naples, Italy.

The search for novel lipid A analogues from any biological source that can act as antagonists, displaying inhibitory activity towards the production of pro-inflammatory cytokines, or as immunomodulators in mammals, is a very topical issue. To this aim, the structure and immunological properties of the lipopolysaccharide lipid A from the purple nonsulfur bacterium Rhodopseudomonas palustris strain BisA53 have been determined. This lipid A displays a unique structural feature, with a non-phosphorylated skeleton made up of the tetrasaccharide Manp-α-(1→4)-GlcpN3N-β-1→6-GlcpN3N-α-(1→1)-α-GalpA, and four primary amide-linked 14:0(3-OH) and, as secondary O-acyl substituents, a 16:0 and the very long-chain fatty acid 26:0(25-OAc), appended on the GlcpN3N units. This lipid A architecture is definitely rare, so far identified only in the genus Bradyrhizobium. Immunological tests on both murine bone-marrow-derived and human monocyte-derived macrophages revealed an extremely low immunostimulant capability of this LPS lipid A.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.201604379DOI Listing
March 2017

Structural Relationship of the Lipid A Acyl Groups to Activation of Murine Toll-Like Receptor 4 by Lipopolysaccharides from Pathogenic Strains of Burkholderia mallei, Acinetobacter baumannii, and Pseudomonas aeruginosa.

Front Immunol 2015 23;6:595. Epub 2015 Nov 23.

Engelhardt Institute of Molecular Biology, Russian Academy of Sciences , Moscow , Russia ; Biological Faculty, Lomonosov Moscow State University , Moscow , Russia.

Toll-like receptor 4 (TLR4) is required for activation of innate immunity upon recognition of lipopolysaccharide (LPS) of Gram-negative bacteria. The ability of TLR4 to respond to a particular LPS species is important since insufficient activation may not prevent bacterial growth while excessive immune reaction may lead to immunopathology associated with sepsis. Here, we investigated the biological activity of LPS from Burkholderia mallei that causes glanders, and from the two well-known opportunistic pathogens Acinetobacter baumannii and Pseudomonas aeruginosa (causative agents of nosocomial infections). For each bacterial strain, R-form LPS preparations were purified by hydrophobic chromatography and the chemical structure of lipid A, an LPS structural component, was elucidated by HR-MALDI-TOF mass spectrometry. The biological activity of LPS samples was evaluated by their ability to induce production of proinflammatory cytokines, such as IL-6 and TNF, by bone marrow-derived macrophages. Our results demonstrate direct correlation between the biological activity of LPS from these pathogenic bacteria and the extent of their lipid A acylation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fimmu.2015.00595DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4655328PMC
December 2015

N-Linked Glycans of Chloroviruses Sharing a Core Architecture without Precedent.

Angew Chem Int Ed Engl 2016 Jan 19;55(2):654-8. Epub 2015 Nov 19.

Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583-0900 (USA).

N-glycosylation is a fundamental modification of proteins and exists in the three domains of life and in some viruses, including the chloroviruses, for which a new type of core N-glycan is herein described. This N-glycan core structure, common to all chloroviruses, is a pentasaccharide with a β-glucose linked to an asparagine residue which is not located in the typical sequon N-X-T/S. The glucose is linked to a terminal xylose unit and a hyperbranched fucose, which is in turn substituted with a terminal galactose and a second xylose residue. The third position of the fucose unit is always linked to a rhamnose, which is a semiconserved element because its absolute configuration is virus-dependent. Additional decorations occur on this core N-glycan and represent a molecular signature for each chlorovirus.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.201509150DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4836869PMC
January 2016

CSF N-glycoproteomics for early diagnosis in Alzheimer's disease.

J Proteomics 2016 Jan 9;131:29-37. Epub 2015 Oct 9.

Institute for Polymers, Composites and Biomaterials-CNR, Via P. Gaifami 18, 95126 Catania, Italy. Electronic address:

This work aims at exploring the human CSF (Cerebrospinal fluid) N-glycome by MALDI MS techniques, in order to assess specific glycosylation pattern(s) in patients with Alzheimer's disease (n:24) and in subjects with mild cognitive impairment (MCI) (n:11), these last as potential AD patients at a pre-dementia stage. For comparison, 21 healthy controls were studied. We identified a group of AD and MCI subjects (about 40-50% of the studied sample) showing significant alteration of CSF N-glycome profiling, consisting of a decrease in the overall sialylation degree and an increase in species bearing bisecting GlcNAc. Noteworthy, all the MCI patients that converted to AD within the clinical follow-up, had an abnormal CSF glycosylation profile. Based on the studied cohort, CSF glycosylation changes may occur before an AD clinical onset. Previous studies specifically focused on the key role of glycosyltransferase GnT-III on AD-pathogenesis, addressing the patho-mechanism to specific sugar modification of BACE-1 glycoprotein with bisecting GlcNAc. Our patients addressed protein N-glycosylation changes at an early phase of the whole biomolecular misregulation on AD, pointing to CSF N-glycome analyses as promising tool to enhance early detection of AD and also suggesting alternative therapeutics target molecules, such as specific glyco-enzymes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jprot.2015.10.006DOI Listing
January 2016

Insect Gut Symbiont Susceptibility to Host Antimicrobial Peptides Caused by Alteration of the Bacterial Cell Envelope.

J Biol Chem 2015 Aug 26;290(34):21042-21053. Epub 2015 Jun 26.

Global Research Laboratory, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea. Electronic address:

The molecular characterization of symbionts is pivotal for understanding the cross-talk between symbionts and hosts. In addition to valuable knowledge obtained from symbiont genomic studies, the biochemical characterization of symbionts is important to fully understand symbiotic interactions. The bean bug (Riptortus pedestris) has been recognized as a useful experimental insect gut symbiosis model system because of its cultivatable Burkholderia symbionts. This system is greatly advantageous because it allows the acquisition of a large quantity of homogeneous symbionts from the host midgut. Using these naïve gut symbionts, it is possible to directly compare in vivo symbiotic cells with in vitro cultured cells using biochemical approaches. With the goal of understanding molecular changes that occur in Burkholderia cells as they adapt to the Riptortus gut environment, we first elucidated that symbiotic Burkholderia cells are highly susceptible to purified Riptortus antimicrobial peptides. In search of the mechanisms of the increased immunosusceptibility of symbionts, we found striking differences in cell envelope structures between cultured and symbiotic Burkholderia cells. The bacterial lipopolysaccharide O antigen was absent from symbiotic cells examined by gel electrophoretic and mass spectrometric analyses, and their membranes were more sensitive to detergent lysis. These changes in the cell envelope were responsible for the increased susceptibility of the Burkholderia symbionts to host innate immunity. Our results suggest that the symbiotic interactions between the Riptortus host and Burkholderia gut symbionts induce bacterial cell envelope changes to achieve successful gut symbiosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.M115.651158DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4543662PMC
August 2015

Determination of the structure of the O-antigen and the lipid A from the entomopathogenic bacterium Pseudomonas entomophila lipopolysaccharide along with its immunological properties.

Carbohydr Res 2015 Aug 1;412:20-7. Epub 2015 May 1.

Dipartimento di Agraria, Via Università 100, 80055 Portici, NA, Italy. Electronic address:

The structure and the immunology of the lipopolysaccharide (LPS) of Pseudomonas entomophila, an entomopathogenic bacterium isolated from the fruit fly Drosophila melanogaster, was characterized. The O-antigen portion was established and resulted to be built up of a repetitive unit constituted by four monosaccharide residues, all L configured, all deoxy at C-6 and with an acetamido function at C-2: →3)-α-l-FucNAc-(1→4)-α-l-FucNAc-(1→3)-α-l-FucNAc-(1→3)-β-l-QuiNAc-(1→ The structural analysis of lipid A, showed a mixture of different species. The diphosphorylated glucosamine backbone carries six fatty acids consistent with the composition C10:0 3(OH), C12:0 2(OH) and C12:0 3(OH), whereas other species differs by the number of phosphates and/or of fatty acids. The immunology experiments demonstrated that the LPS structure of P. entomophila displayed a low ability to engage the TLR4-mediated signaling correlated to a significant antagonistic activity toward hexa-acylated LPS structures.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carres.2015.04.017DOI Listing
August 2015

Covalently linked hopanoid-lipid A improves outer-membrane resistance of a Bradyrhizobium symbiont of legumes.

Nat Commun 2014 Oct 30;5:5106. Epub 2014 Oct 30.

Dipartimento di Scienze Chimiche, Complesso Universitario Monte Sant'Angelo, Università di Napoli Federico II, Via Cintia 4, Napoli I-80126, Italy.

Lipopolysaccharides (LPSs) are major components of the outer membrane of Gram-negative bacteria and are essential for their growth and survival. They act as a structural barrier and play an important role in the interaction with eukaryotic hosts. Here we demonstrate that a photosynthetic Bradyrhizobium strain, symbiont of Aeschynomene legumes, synthesizes a unique LPS bearing a hopanoid covalently attached to lipid A. Biophysical analyses of reconstituted liposomes indicate that this hopanoid-lipid A structure reinforces the stability and rigidity of the outer membrane. In addition, the bacterium produces other hopanoid molecules not linked to LPS. A hopanoid-deficient strain, lacking a squalene hopene cyclase, displays increased sensitivity to stressful conditions and reduced ability to survive intracellularly in the host plant. This unusual combination of hopanoid and LPS molecules may represent an adaptation to optimize bacterial survival in both free-living and symbiotic states.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/ncomms6106DOI Listing
October 2014

Thermophiles as potential source of novel endotoxin antagonists: the full structure and bioactivity of the lipo-oligosaccharide from Thermomonas hydrothermalis.

Chembiochem 2014 Sep 29;15(14):2146-55. Epub 2014 Aug 29.

Dipartimento di Scienze Chimiche, Università di Napoli "Federico II", Complesso Universitario Monte S.Angelo, Via Cintia 4, 80126 Napoli (Italy).

Thermomonas hydrothermalis is a Gram-negative thermophilic bacterium that is able to live at 50 °C. This ability is attributed to chemical modifications, involving those to bacterial cell-wall components, such as proteins and (glyco)lipids. As the main component of the outer membrane of Gram-negative bacteria, lipopolysaccharides (LPSs) are exposed to the environment, thus they can undergo structural chemical changes to allow thermophilic bacteria to live at their optimal growth temperature. Furthermore, as one of the major target of the eukaryotic innate immune system, LPS elicits host immune response in a structure-dependent mode; thus the uncommon chemical features of thermophilic bacterial LPSs might exert a different biological action on the innate immune system-an antagonistic effect, as shown in studies of LPS structure-activity relationship in the ongoing research into antagonist LPS candidates. Here, we report the complete structural and biological activity analysis of the lipo-oligosaccharide isolated from Thermomonas hydrothermalis, achieved by a multidisciplinary approach (chemical analysis, NMR, MALDI MS and cellular immunology). We demonstrate a tricky and interesting structure combined with a very interesting effect on human innate immunity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cbic.201402233DOI Listing
September 2014

Persistent cystic fibrosis isolate Pseudomonas aeruginosa strain RP73 exhibits an under-acylated LPS structure responsible of its low inflammatory activity.

Mol Immunol 2015 Feb 22;63(2):166-75. Epub 2014 May 22.

Dipartimento di Scienze Chimiche, Università di Napoli "Federico II", Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126 Napoli, Italy. Electronic address:

Pseudomonas aeruginosa, the major pathogen involved in lethal infections in cystic fibrosis (CF) population, is able to cause permanent chronic infections that can persist over the years. This ability to chronic colonize CF airways is related to a series of adaptive bacterial changes involving the immunostimulant lipopolysaccharide (LPS) molecule. The structure of LPSs isolated from several P. aeruginosa strains showed conserved features that can undergo chemical changes during the establishment of the chronic infection. In the present paper, we report the elucidation of the structure and the biological activity of the R-LPS (lipooligosaccharide, LOS) isolated from the persistent CF isolate P. aeruginosa strain RP73, in order to give further insights in the adaptation mechanism of the pathogen in the CF environment. The complete structural analysis of P. aeruginosa RP73 LOS was achieved by chemical analyses, NMR spectroscopy and MALDI MS spectrometry, while the assessment of the biological activity was attained testing the in vivo pro-inflammatory capacity of the isolated LOS molecule. While a typical CF LPS is able to trigger a high immune response and production of pro-inflammatory molecules, this P. aeruginosa RP73 LOS showed to possess a low pro-inflammatory capacity. This was possible due to a singular chemical structure possessing an under-acylated lipid A very similar to the LPS of P. aeruginosa found in chronic lung diseases such as bronchiectstasis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.molimm.2014.04.004DOI Listing
February 2015

MAN1B1 deficiency: an unexpected CDG-II.

PLoS Genet 2013 12;9(12):e1003989. Epub 2013 Dec 12.

Center for Human Genetics, University of Leuven, Leuven, Belgium.

Congenital disorders of glycosylation (CDG) are a group of rare metabolic diseases, due to impaired protein and lipid glycosylation. In the present study, exome sequencing was used to identify MAN1B1 as the culprit gene in an unsolved CDG-II patient. Subsequently, 6 additional cases with MAN1B1-CDG were found. All individuals presented slight facial dysmorphism, psychomotor retardation and truncal obesity. Generally, MAN1B1 is believed to be an ER resident alpha-1,2-mannosidase acting as a key factor in glycoprotein quality control by targeting misfolded proteins for ER-associated degradation (ERAD). However, recent studies indicated a Golgi localization of the endogenous MAN1B1, suggesting a more complex role for MAN1B1 in quality control. We were able to confirm that MAN1B1 is indeed localized to the Golgi complex instead of the ER. Furthermore, we observed an altered Golgi morphology in all patients' cells, with marked dilatation and fragmentation. We hypothesize that part of the phenotype is associated to this Golgi disruption. In conclusion, we linked mutations in MAN1B1 to a Golgi glycosylation disorder. Additionally, our results support the recent findings on MAN1B1 localization. However, more work is needed to pinpoint the exact function of MAN1B1 in glycoprotein quality control, and to understand the pathophysiology of its deficiency.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pgen.1003989DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3861123PMC
August 2014

Intracellular Shigella remodels its LPS to dampen the innate immune recognition and evade inflammasome activation.

Proc Natl Acad Sci U S A 2013 Nov 28;110(46):E4345-54. Epub 2013 Oct 28.

Dipartimento di Biologia e Biotecnologie C. Darwin and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza-Università di Roma, 00185 Rome, Italy.

LPS is a potent bacterial effector triggering the activation of the innate immune system following binding with the complex CD14, myeloid differentiation protein 2, and Toll-like receptor 4. The LPS of the enteropathogen Shigella flexneri is a hexa-acylated isoform possessing an optimal inflammatory activity. Symptoms of shigellosis are produced by severe inflammation caused by the invasion process of Shigella in colonic and rectal mucosa. Here we addressed the question of the role played by the Shigella LPS in eliciting a dysregulated inflammatory response of the host. We unveil that (i) Shigella is able to modify the LPS composition, e.g., the lipid A and core domains, during proliferation within epithelial cells; (ii) the LPS of intracellular bacteria (iLPS) and that of bacteria grown in laboratory medium differ in the number of acyl chains in lipid A, with iLPS being the hypoacylated; (iii) the immunopotential of iLPS is dramatically lower than that of bacteria grown in laboratory medium; (iv) both LPS forms mainly signal through the Toll-like receptor 4/myeloid differentiation primary response gene 88 pathway; (v) iLPS down-regulates the inflammasome-mediated release of IL-1β in Shigella-infected macrophages; and (vi) iLPS exhibits a reduced capacity to prime polymorfonuclear cells for an oxidative burst. We propose a working model whereby the two forms of LPS might govern different steps of the invasive process of Shigella. In the first phases, the bacteria, decorated with hypoacylated LPS, are able to lower the immune system surveillance, whereas, in the late phases, shigellae harboring immunopotent LPS are fully recognized by the immune system, which can then successfully resolve the infection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1303641110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3832022PMC
November 2013

Mutations in SLC35A3 cause autism spectrum disorder, epilepsy and arthrogryposis.

J Med Genet 2013 Nov 12;50(11):733-9. Epub 2013 Sep 12.

Monique and Jacques Roboh, Department of Genetic Research, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.

Background: The heritability of autism spectrum disorder is currently estimated at 55%. Identification of the molecular basis of patients with syndromic autism extends our understanding of the pathogenesis of autism in general. The objective of this study was to find the gene mutated in eight patients from a large kindred, who suffered from autism spectrum disorder, arthrogryposis and epilepsy.

Methods And Results: By linkage analysis and exome sequencing, we identified deleterious mutations in SLC35A3 in these patients. SLC35A3 encodes the major Golgi uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) transporter. In Golgi vesicles isolated from patient fibroblasts the transport of the respective nucleotide sugar was significantly reduced causing a massive decrease in the content of cell surface expressed highly branched N-glycans and a concomitant sharp increase of lower branched glycoforms.

Conclusions: Spontaneous mutation in SLC35A3 has been discovered in cattle worldwide, recapitulating the human phenotype with arthrogryposis and additional skeletal defects known as Complex Vertebral Malformation syndrome. The skeletal anomalies in the mutant cattle and in our patients, and perhaps even the neurological symptoms are likely the consequence of the lack of high-branched N-glycans and the concomitant abundance of lower-branched glycoforms at the cell surface. This pattern has previously been associated with growth arrest and induction of differentiation. With this study, we add SLC35A3 to the gene list of autism spectrum disorders, and underscore the crucial importance of UDP-GlcNAc in the regulation of the N-glycan branching pathway in the Golgi apparatus.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/jmedgenet-2013-101753DOI Listing
November 2013