Search Results (12)

Rafiq syndrome (RAFQS) is a rare autosomal recessive disorder that is classified as a type II congenital disorder of glycosylation (CDG-II), and caused by MAN1B1 gene mutation. To date, 24 pathogenic MAN1B1 mutations have been reported in association with MAN1B1-CDG. However, the underlying pathogenic mechanisms remain poorly understood. In this study, we recruited a consanguineous family from Pakistan with multiple affected individuals exhibiting mild facial dysmorphism, developmental delay, and intellectual disability. Utilizing exome sequencing and homozygosity mapping, we identified a novel MAN1B1 mutation (c.772_775del) that co-segregated with RAFQS in this family. Analysis of public single-cell transcriptomic data revealed that MAN1B1 is predominantly expressed in dorsal progenitors and intermediate excitatory neurons during human brain development. Knockdown of Man1b1 in primarily cultured mouse excitatory neurons disrupted axon growth, dendrite formation, and spine maturation, and could not be rescued by truncated variants identified in the family. Furthermore, in utero, electroporation experiments revealed that Man1b1 knockdown in the murine cortex impaired neural stem cells’ proliferation and differentiation, as well as cortical neuron migration. Collectively, these findings elucidate a critical role for MAN1B1 in the etiology of RAFQS and demonstrate that loss-of-function mutation in MAN1B1 disrupt neuro-developmental processes, providing mechanistic insights into the pathogenesis of this disorder. Full article

Autism Spectrum Disorder (ASD) is a complex condition with a multifactorial aetiology including both genetic and epigenetic factors. MicroRNAs (miRNAs) play a role in ASD and may influence metabolic pathways. Glycosylation (the glycoconjugate synthesis pathway) is a necessary process for the optimal development of the central nervous system (CNS). Congenital Disorders of Glycosylation (CDGs) (CDGs) are linked to over 180 genes and are predominantly associated with neurodevelopmental disorders (NDDs) including ASD. From a literature search, we considered 64 miRNAs consistently deregulated in ASD patients (ASD-miRNAs). Computational tools, including DIANA-miRPath v3.0 and TarBase v8, were employed to investigate the potential involvement of ASD-miRNAs in glycosylation pathways. A regulatory network constructed through miRNet 2.0 revealed the involvement of these miRNAs in targeting genes linked to glycosylation. Protein functions were further validated through the Human Protein Atlas. A total of twenty-five ASD-miRNAs were identified, including nine miRNAs that were differentially expressed in cells or brain tissue in ASD patients and associated with glycosylation pathways, specifically protein N- and O-glycosylation and glycosaminoglycan biosynthesis (heparan sulfate). A number of CDG genes and/or ASD-risk genes, including DOLK, GALNT2, and EXT1, were identified as targets, along with validated interactions involving four key miRNAs (hsa-miR-423-5p, hsa-miR-30c-5p, hsa-miR-195-5p, and hsa-miR-132-5p). B4GALT1, an ASD susceptibility gene, emerged as a central regulatory hub, reinforcing the link between glycosylation and ASD. In sum, the evidence presented here supports the hypothesis that ASD-miRNAs mediate the epigenetic regulation of glycosylation, thus unveiling possible novel patho-mechanisms underlying ASD. Full article

Carotenoids from different sources have different structures and functions, and their dietary components benefit the health of various organisms. The effects of halophilic Archaea-derived C50 carotenoids on poultry egg quality and gut microbiota remain largely unexplored. In this study, we isolated a carotenoid-secreting strain of Halalkalicoccus paucihalophilus, TRM89021, from the Pamir Plateau. We characterized the carotenoid pigments produced by this strain; the major components were bacterioruberin and its derivatives. The effects of these carotenoids on the egg quality and cecal microbiota composition of hens were investigated. Compared to the basal diet group (BDG), supplementation with carotenoids in the carotenoids-supplemented diet group (CDG) resulted in significantly lower a* and b* scores at week 5 and lower b* scores and Haugh units at week 2, while egg strength and weight were higher. CDG also showed increased yolk antioxidant capacity, higher glutathione peroxidase levels, and significantly lower catalase levels (p < 0.05). Plasma analysis revealed elevated total bilirubin and aspartate aminotransferase levels, along with reduced inorganic phosphorus levels in the CDG (p < 0.05). No significant differences in cecal microbiota diversity were observed between the groups at any taxonomic level. This result suggests that halophilic archaea-derived carotenoids have the potential to be used as natural feed supplements to improve egg quality. Our study provides a theoretical basis for applying archaea-derived carotenoids in poultry diets. Full article

Bis (3′,5′)-cyclic diguanylic acid (c-di-GMP) is a ubiquitous second messenger that controls several metabolic pathways in bacteria. In Streptomyces, c-di-GMP is associated with morphological differentiation, which is related to secondary metabolite production. In this study, we identified and characterized a diguanylate cyclase (DGC), CdgB, from Streptomyces diastatochromogenes 1628, which may be involved in c-di-GMP synthesis, through genetic and biochemical analyses. To further investigate the role of CdgB, the cdgB-deleted mutant strain Δ-cdgB and the cdgB-overexpressing mutant strain O-cdgB were constructed by genetic engineering. A phenotypic analysis revealed that the O-cdgB colonies exhibited reduced mycelium formation, whereas the Δ-cdgB colonies displayed wrinkled surfaces and shriveled mycelia. Notably, O-cdgB demonstrated a significant increase in the toyocamycin (TM) yield by 47.3%, from 253 to 374 mg/L, within 10 days. This increase was accompanied by a 6.7% elevation in the intracellular concentration of c-di-GMP and a higher transcriptional level of the toy cluster within four days. Conversely, Δ-cdgB showed a lower c-di-GMP concentration (reduced by 6.2%) in vivo and a reduced toyocamycin production (decreased by 28.9%, from 253 to 180 mg/L) after 10 days. In addition, S. diastatochromogenes 1628 exhibited a slightly higher inhibitory effect against Fusarium oxysporum f. sp. cucumerinum and Rhizoctonia solani compared to Δ-cdgB, but a lower inhibition rate than that of O-cdgB. The results imply that CdgB provides a foundational function for metabolism and the activation of secondary metabolism in S. diastatochromogenes 1628. Full article

As important livestock species, pigs provide essential meat resources for humans, so understanding the genetic evolution behind their domestic history could help with the genetic improvement of domestic pigs. This study aimed to investigate the evolution of convergence and divergence under selection in European and Asian domestic pigs by using public genome-wide data. A total of 164 and 108 candidate genes (CDGs) were obtained from the Asian group (wild boar vs. domestic pig) and the European group (wild boar vs. domestic pig), respectively, by taking the top 5% of intersected windows of a pairwise fixation index (FST) and a cross population extended haplotype homozygosity test (XPEHH). GO and KEGG annotated results indicated that most CDGs were related to reproduction and immunity in the Asian group. Conversely, rich CDGs were enriched in muscle development and digestion in the European group. Eight CDGs were subjected to parallel selection of Eurasian domestic pigs from local wild boars during domestication. These CDGs were mainly involved in olfactory transduction, metabolic pathways, and progesterone-mediated oocyte maturation. Moreover, 36 and 18 haplotypes of INPP5B and TRAK2 were identified in this study, respectively. In brief, this study did not only improve the understanding of the genetic evolution of domestication in pigs, but also provides valuable CDGs for future breeding and genetic improvement of pigs. Full article

A Ni-based powder composed of NiSiB + 60% WC was deposited onto a structural-steel substrate using two methods: laser cladding (LC) and plasma powder transferred arc welding (PPTAW). The resulting surface layers were analyzed and compared. Both methods resulted in the precipitation of secondary WC phases in the solidified matrix, but the PPTAW clad exhibited a dendritic microstructure. The microhardness of the clads prepared by both methods was similar, but the PPTAW clad showed higher resistance to abrasive wear compared to the LC clad. The thickness of the transition zone (TZ) was thin for both methods, with a coarse-grain heat-affected zone (CGHAZ) and peninsula-like macrosegregations observed in clads from both methods. The PPTAW clad showed a unique cellular–dendritic growth solidification (CDGS) and a type-II boundary at the TZ attributed to its thermal cycles. While both methods resulted in metallurgical bonding of the clad to the substrate, the LC method exhibited a lower dilution coefficient. The LC method also resulted in a larger HAZ with higher hardness compared to the HAZ of the PPTAW clad. The findings of this study indicate that both methods are promising for antiwear applications due to their wear-resistant properties and metallurgical bonding to the substrate. The PPTAW clad may be particularly useful in applications that require higher resistance to abrasive wear, while the LC method may be advantageous in applications that require lower dilution and larger HAZ. Full article

Among cyclic di-nucleotides (CDN), both cyclic di-AMP (CDA) and di-GMP (CDG) are promising adjuvants and immune modulators. These molecules are not only able to induce profuse antibody production but also predominant T helper 1 and cytotoxic CD8 T lymphocytes (CTL) responses, which enable their use for vaccination against intracellular pathogens as well as in cancer immunotherapy. However, for their successful translation into the clinic, a comprehensive understanding of CDN mode of action is still essential. Consistent with evidence in the literature, we show here that IFN-α/β (Type I IFN) is crucial for CDG-mediated B cell activation. We recently determined the key role of type I IFN signaling for CDA-mediated enhancement of immunogenicity. Based on the biological activities of type I IFN, in this study, we hypothesized that it might also be required for CTL induction by CDG. We disclose here the mode of action of type I IFN signaling in CDG-mediated cross-presentation and subsequent CTL generation. Full article

Rafiq syndrome (RAFQS) is a congenital disorder of glycosylation (CDG) that is caused by mutations in the MAN1B1 gene and characterized by impaired protein and lipid glycosylation. RAFQS is characterized by a delay in intellectual and motor development, facial and other dysmorphism, truncal obesity, behavior problems, and hypotonia. We describe a Russian patient with delayed intellectual and motor development, a lack of speech, disorientation in space and time, impaired attention and memory, and episodes of aggression. Screening for lysosomal, amino acid, organic acid, and mitochondrial disorders was normal. The patient was referred for the targeted sequencing of the “Hereditary Metabolic Disorders” panel. The genetic testing revealed two heterozygous pathogenic variants in the MAN1B1 gene: the previously reported c.1000C > T (p.Arg334Cys) and the novel c.1065 + 1 G > C. Thus, the patient’s clinical picture and genetic analysis confirmed RAFQS in the patient. Full article

Congenital disorders of glycosylation (CDG), inherited metabolic diseases caused by defects in glycosylation, are characterized by a high frequency of intellectual disability (ID) and various clinical manifestations. Two siblings with ID, dysmorphic features, and epilepsy were examined using mass spectrometry of serum transferrin, which revealed a CDG type 2 pattern. Whole-exome sequencing showed that both patients were homozygous for a novel pathogenic variant of MAN1B1 (NM_016219.4:c.1837del) inherited from their healthy parents. We conducted a HPLC analysis of sialylated N-linked glycans released from total plasma proteins and characterized the α1,2-mannosidase I activity of the lymphocyte microsome fraction. The accumulation of monosialoglycans was observed in MAN1B1-deficient patients, indicating N-glycan-processing defects. The enzymatic activity of MAN1B1 was compromised in patient-derived lymphocytes. The present patients exhibited unique manifestations including early-onset epileptic encephalopathy and cerebral infarction. They also showed coagulation abnormalities and hypertransaminasemia. Neither sibling had truncal obesity, which is one of the characteristic features of MAN1B1-CDG. Full article

Inflammation is a defense mechanism that protects the body from infections. However, chronic inflammation causes damage to body tissues. Thus, controlling inflammation and investigating anti-inflammatory mechanisms are keys to preventing and treating inflammatory diseases, such as sepsis and rheumatoid arthritis. In continuation with our work related to the discovery of bioactive natural products, a polyphenol, catechin-7,4′-O-digallate (CDG), was isolated from Woodfordia uniflora, which has been used as a sedative and remedy for skin infections in the Dhofar region of Oman. Thus far, no study has reported the anti-inflammatory compounds derived from W. uniflora and the mechanisms underlying their action. To investigate the effects of CDG on the regulation of inflammation, we measured the reduction in nitric oxide (NO) production following CDG treatment in immortalized mouse Kupffer cells (ImKCs). CDG treatment inhibited NO production through the downregulation of inducible nitric oxide synthase expression in lipopolysaccharide (LPS)-stimulated ImKCs. The anti-inflammatory effects of CDG were mediated via the inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation, an important inflammatory-response-associated signaling pathway. Moreover, CDG treatment has regulated the expression of pro-inflammatory cytokines, such as IL-6 and IL-1β. These results suggested the anti-inflammatory action of CDG in LPS-stimulated ImKCs. Full article

Asparagine-linked glycosylation, also known as N-linked glycosylation is an essential and highly conserved post-translational protein modification that occurs in all three domains of life. This modification is essential for specific molecular recognition, protein folding, sorting in the endoplasmic reticulum, cell–cell communication, and stability. Defects in N-linked glycosylation results in a class of inherited diseases known as congenital disorders of glycosylation (CDG). N-linked glycosylation occurs in the endoplasmic reticulum (ER) lumen by a membrane associated enzyme complex called the oligosaccharyltransferase (OST). In the central step of this reaction, an oligosaccharide group is transferred from a lipid-linked dolichol pyrophosphate donor to the acceptor substrate, the side chain of a specific asparagine residue of a newly synthesized protein. The prokaryotic OST enzyme consists of a single polypeptide chain, also known as single subunit OST or ssOST. In contrast, the eukaryotic OST is a complex of multiple non-identical subunits. In this review, we will discuss the biochemical and structural characterization of the prokaryotic, yeast, and mammalian OST enzymes. This review explains the most recent high-resolution structures of OST determined thus far and the mechanistic implication of N-linked glycosylation throughout all domains of life. It has been shown that the ssOST enzyme, AglB protein of the archaeon Archaeoglobus fulgidus, and the PglB protein of the bacterium Campylobactor lari are structurally and functionally similar to the catalytic Stt3 subunit of the eukaryotic OST enzyme complex. Yeast OST enzyme complex contains a single Stt3 subunit, whereas the human OST complex is formed with either STT3A or STT3B, two paralogues of Stt3. Both human OST complexes, OST-A (with STT3A) and OST-B (containing STT3B), are involved in the N-linked glycosylation of proteins in the ER. The cryo-EM structures of both human OST-A and OST-B complexes were reported recently. An acceptor peptide and a donor substrate (dolichylphosphate) were observed to be bound to the OST-B complex whereas only dolichylphosphate was bound to the OST-A complex suggesting disparate affinities of two OST complexes for the acceptor substrates. However, we still lack an understanding of the independent role of each eukaryotic OST subunit in N-linked glycosylation or in the stabilization of the enzyme complex. Discerning the role of each subunit through structure and function studies will potentially reveal the mechanistic details of N-linked glycosylation in higher organisms. Thus, getting an insight into the requirement of multiple non-identical subunits in the N-linked glycosylation process in eukaryotes poses an important future goal. Full article

High concentrations of Na⁺ or [Co(NH₃)₆]³⁺ can induce the B to Z conformational transition in alternating (dC-dG) oligo and polynucleotides. The use of short DNA oligomers (dC-dG)₄ and (dm⁵C-dG)₄ as models can allow a thermodynamic characterization of the transition. Both form right handed double helical structures (B-DNA) in standard phosphate buffer with 115 mM Na⁺ at 25 °C. However, at 2.0 M Na⁺ or 200 μM [Co(NH₃)₆]³⁺, (dm⁵C-dG)₄ assumes a left handed double helical structure (Z-DNA) while the unmethylated (dC-dG)₄ analogue remains right handed under those conditions. We have previously demonstrated that the enthalpy of the transition at 25 °C for either inducer can be determined using isothermal titration calorimetry (ITC). Here, ITC is used to investigate the linkages between temperature, water activity and DNA conformation. We found that the determined enthalpy for each titration varied linearly with temperature allowing determination of the heat capacity change (ΔC_p) between the initial and final states. As expected, the ΔC_p values were dependent upon the cation (i.e., Na⁺ vs. [Co(NH₃)₆]³⁺) as well as the sequence of the DNA oligomer (i.e., methylated vs. unmethylated). Osmotic stress experiments were carried out to determine the gain or loss of water by the oligomer induced by the titration. The results are discussed in terms of solvent accessible surface areas, electrostatic interactions and the role of water. Full article