Vitamin B12 responsive developmental and epileptic encephalopathy due to a novel mutation in the FUT2 gene: a case report.

BACKGROUND: Vitamin B12 deficiency is a recognised cause of neurological manifestations, including peripheral neuropathy, behavioural changes, and seizures. However, developmental and epileptic encephalopathy due to vitamin B12 deficiency is very rare. Here, we report an infant with vitamin B12-responsive developmental and epileptic encephalopathy due to a novel mutation in the fucosyltransferase 2 (FUT2) gene responsible for vitamin B12 absorption. CASE PRESENTATION: An 11-month-old girl of non-consanguineous parents presented with recurrent episodes of seizures since four months. Her seizures started as flexor epileptic spasms occurring in clusters resembling infantile epileptic spasms syndrome with hypsarrhythmia in the electroencephalogram. She was treated with multiple drugs, including high-dose prednisolone, vigabatrin, sodium valproate, levetiracetam and clobazam, without any response, and she continued to have seizures at 11 months. She had an early developmental delay with maximally achieving partial head control and responsive smile at four months. Her development regressed with the onset of seizure; at 11 months, her developmental age was below six weeks. On examination, she was pale and had generalised hypotonia with normal muscle power and reflexes. Her full blood count and blood picture revealed macrocytic anaemia with oval and round macrocytes. Bone marrow aspiration showed hypercellular marrow erythropoiesis with normoblastic and megaloblastic maturation. Due to the unusual association of refractory epilepsy and megaloblastic anaemia, a rare genetic disease of the vitamin B12 or folate pathways was suspected. The whole exome sequencing revealed a homozygous missense variant in exon 2 of the FUT2 gene associated with reduced vitamin B12 absorption and low plasma vitamin B12 levels, confirming the diagnosis of vitamin B12 deficiency related developmental and epileptic encephalopathy. She was started on intramuscular hydroxocobalamin, for which she showed a marked response with reduced seizure frequency. CONCLUSION: We report a novel variant in the FUT2 gene associated with vitamin B12-responsive developmental and epileptic encephalopathy and megaloblastic anaemia. This case report highlights the importance of timely genetic testing in children with refractory developmental and epileptic encephalopathy to identify treatable causes.

FUT6 Suppresses the Proliferation, Migration, Invasion, and Epithelial-Mesenchymal Transition of Esophageal Carcinoma Cells via the Epidermal Growth Factor Receptor/Extracellular Signal-Regulated Kinase Signaling Pathway.

Esophageal cancer (ESCA) is a high-incidence disease worldwide, of which the 5-year survival rate remains dismal since the cellular basis of ESCA remains largely unclear. Herein, we attempted to examine the manifestation of fucosyltransferase-6 (FUT6) in ESCA and the associated mechanisms. The GSE161533 dataset was used to analyze a crucial gene in ESCA. The expression of FUT6 was investigated in normal esophageal epithelial cells and ESCA cell lines. Following FUT6 knockdown or overexpression, cell proliferation, migration, invasion, and levels of epithelial­mesenchymal transition (EMT)-related and epidermal growth factor receptor (EGFR)/extracellular signal-regulated kinase (ERK) signaling pathway-related proteins were evaluated using CCK-8, Transwell, and Western blotting with antibodies against EGFR, p-EGFR, E-cadherin, Vimentin, N-cadherin, ERK1/2, and p-ERK1/2), respectively. EGF was administered to stimulate the EGFR/ERK signaling pathway, followed by the assessment of cellular activity. Database analysis revealed that FUT6 was downregulated in the ESCA cells. Our study indicated that FUT6 is suppressed in various ESCA cell lines. Moreover, cell proliferation, invasion, migration, and EMT-related protein levels were conspicuously enhanced or restrained by FUT6 disruption or overexpression. FUT6 overexpression suppressed the malignant activities of the cells when stimulated by EGF, including inhibition of cell growth, movement, invasion, and EMT advancement, as well the reduction the levels of EGFR/ERK pathway proteins. In conclusion, FUT6 can suppress the EGFR/ERK signaling pathway activated by EGF, leading to the potential attenuation of ESCA cell proliferation, invasion, migration, and EMT.

Interplay between de novo and salvage pathways of GDP-fucose synthesis.

GDP-fucose is synthesised via two pathways: de novo and salvage. The first uses GDP-mannose as a substrate, and the second uses free fucose. To date, these pathways have been considered to work separately and not to have an influence on each other. We report the mutual response of the de novo and salvage pathways to the lack of enzymes from a particular route of GDP-fucose synthesis. We detected different efficiencies of GDP-fucose and fucosylated structure synthesis after a single inactivation of enzymes of the de novo pathway. Our study demonstrated the unequal influence of the salvage enzymes on the production of GDP-fucose by enzymes of the de novo biosynthesis pathway. Simultaneously, we detected an elevated level of one of the enzymes of the de novo pathway in the cell line lacking the enzyme of the salvage biosynthesis pathway. Additionally, we identified dissimilarities in fucose uptake between cells lacking TSTA3 and GMDS proteins.

H Antigen expression modulates epidermal Keratinocyte Integrity and differentiation.

BACKGROUND: ABO blood group antigens (ABH antigens) are carbohydrate chains glycosylated on epithelial and red blood cells. Recent findings suggest reduced ABH expression in psoriasis and atopic dermatitis, a chronic inflammatory skin disease with retained scale. H antigen, a precursor for A and B antigens, is synthesized by fucosyltransferase 1 (FUT1). Desmosomes, critical for skin integrity, are known to require N-glycosylation for stability. We investigate the impact of H antigens, a specific type of glycosylation, on desmosomes in keratinocytes. METHOD: Primary human keratinocytes were transfected with FUT1 siRNA or recombinant adenovirus for FUT1 overexpression. Cell adhesion and desmosome characteristics and their underlying mechanisms were analyzed. RESULT: The knockdown of FUT1, responsible for H2 antigen expression in the skin, increased cell-cell adhesive strength and desmosome size in primary cultured keratinocytes without altering the overall desmosome structure. Desmosomal proteins, including desmogleins or plakophilin, were upregulated, suggesting enhanced desmosome assembly. Reduced H2 antigen expression via FUT1 knockdown led to increased keratinocyte differentiation, evidenced by elevated expression of differentiation markers. Epidermal growth factor receptor (EGFR) has been described to be associated with FUT1 and promotes cell migration and differentiation. The effects of FUT1 knockdown were recapitulated by an EGFR inhibitor concerning desmosomal proteins and cellular differentiation. Further investigation demonstrated that the FUT1 knockdown reduced EGFR signaling by lowering the levels of EGF ligands rather than directly regulating EGFR activity. Moreover, FUT1 overexpression reversed the effects observed in FUT1 knockdown, resulting in the downregulation of desmosomal proteins and differentiation markers while increasing both mRNA and protein levels of EGFR ligands. CONCLUSION: The expression level of FUT1 in the epidermis appears to influence cell-cell adhesion and keratinocyte differentiation status, at least partly through regulation of H2 antigen and EGFR ligand expression. These observations imply that the fucosylation of the H2 antigen by FUT1 could play a significant role in maintaining the molecular composition and regulation of desmosomes and suggest a possible involvement of the altered H2 antigen expression in skin diseases, such as psoriasis and atopic dermatitis.

FUT2 promotes colorectal cancer metastasis by reprogramming fatty acid metabolism via YAP/TAZ signaling and SREBP-1.

Colorectal cancer (CRC) ranks as the second most lethal cancer worldwide because of its high rate of metastasis, and approximately 20% of CRC patients have metastases at initial diagnosis. Metabolic reprogramming, a hallmark of cancer cells, has been implicated in the process of metastasis. We previously demonstrated that fucosyltransferase 2 (FUT2) promotes the malignancy of CRC cells, however, the underlying mechanisms remain unclear. Here, bioinformatic analysis revealed that FUT2 is associated with the malignant phenotype and fatty acid metabolism in CRC. FUT2 knockdown decreased glucose uptake and de novo fatty acid synthesis, which in turn inhibited the proliferation and metastasis of CRC cells. Mechanistically, FUT2 promotes YAP1 nuclear translocation and stabilizes mSREBP-1 by fucosylation, thus promoting de novo fatty acid synthesis in CRC cells. In summary, this study demonstrates that FUT2 promotes the proliferation and metastasis of CRC cells by reprogramming fatty acid metabolism via YAP/TAZ signaling and SREBP-1, indicating that FUT2 might be a potential target for developing therapeutic strategies against CRC.

Human milk oligosaccharides are associated with maternal genetics and respiratory health of human milk-fed children.

Breastfeeding provides many health benefits, but its impact on respiratory health remains unclear. This study addresses the complex and dynamic nature of the mother-milk-infant triad by investigating maternal genomic factors regulating human milk oligosaccharides (HMOs), and their associations with respiratory health among human milk-fed infants. Nineteen HMOs are quantified from 980 mothers of the CHILD Cohort Study. Genome-wide association studies identify HMO-associated loci on chromosome 19p13.3 and 19q13.33 (lowest P = 2.4e-118), spanning several fucosyltransferase (FUT) genes. We identify novel associations on chromosome 3q27.3 for 6'-sialyllactose (P = 2.2e-9) in the sialyltransferase (ST6GAL1) gene. These, plus additional associations on chromosomes 7q21.32, 7q31.32 and 13q33.3, are replicated in the independent INSPIRE Cohort. Moreover, gene-environment interaction analyses suggest that fucosylated HMOs may modulate overall risk of recurrent wheeze among preschoolers with variable genetic risk scores (P < 0.01). Thus, we report novel genetic factors associated with HMOs, some of which may protect the respiratory health of children.

The contribution of fucosyltransferases to cancer biology.

Fucosyltransferases are enzymes that transfer L-fucose residues from a donor substrate to target molecules. These enzymes are encoded by genes known as FUTs (FUT1 to FUT-11), along with POFUT1 and 2. Changes in FUT expression have a significant role in cancer development and malignancy. This review delves into the biochemistry and biological functions of FUTs and their contributions to cancer. Broadly, FUTs play roles in cancer tumorigenesis, survival, and metastasis. Interactions between fucosylated glycans and various molecules associated with cancer, such as E-selectins and the epidermal growth factor receptor (EGFR), offer alternative pathways for cancer development. The review also highlights FUTs as potential biomarkers for cancer prognosis and diagnosis, along with their application as targets for therapy.

Chemo-sensory loss and FUT2 gene in COVID-19 infected Iraqi dentists.

OBJECTIVE: Aim: To find any association between specific ABO blood groups and FUT2 secretory status and COVID-19 in a sample of Iraqi dentists. PATIENTS AND METHODS: Materials and Methods: For each participant, a questionnaire including demography, COVID-19 status, blood grouping, and RH factor, with chemo-sensitive symptoms was recorded. The saliva samples were collected and DNA was extracted from leukocytes. Sequencing of molecular detection of the FUT2 gene by real-time PCR and the data was done, whilst drawing the phylogenetic tree. RESULTS: Results: Out of 133, most of the dentists were female 61%, most were just under 35 years of age. The most participants in this study were predominantly with blood group O (40%), followed by B, A, and AB, with (90%) of them were RH+. All blood grouping and RH factor were high significantly associated with COVID-19 infection and its frequency (p<0.001). A significant association between smell dysfunction and infected blood group A and RH+ (p =0.044, 0.038) while taste dysfunction was negatively and significantly correlated with AB group (r=-0.73; p=0.008). The FUT2 secretor showed a significant association with COVID-19 infection and frequency. The majority of COVID-19-infected participants experienced a significant loss of both smell and taste with fast recovery within 2 weeks. CONCLUSION: Conclusions: The COVID-19 infection susceptibility and reinfection are associated with FUT2 secretory status and greatly associated to olfactory and gustatory sense loss.

Bifidobacterium longum and microbiome maturation modify a nutrient intervention for stunting in Zimbabwean infants.

BACKGROUND: Small-quantity lipid-based nutrient supplements (SQ-LNS), which has been widely tested to reduce child stunting, has largely modest effects to date, but the mechanisms underlying these modest effects are unclear. Child stunting is a longstanding indicator of chronic undernutrition and it remains a prevalent public health problem. The infant gut microbiome may be a key contributor to stunting; and mother and infant fucosyltransferase (FUT) phenotypes are important determinants of infant microbiome composition. METHODS: We investigated whether mother-infant FUT status (n = 792) and infant gut microbiome composition (n = 354 fecal specimens from 172 infants) modified the impact of an infant and young child feeding (IYCF) intervention, that included SQ-LNS, on stunting at age 18 months in secondary analysis of a randomized trial in rural Zimbabwe. FINDINGS: We found that the impact of the IYCF intervention on stunting was modified by: (i) mother-infant FUT2+/FUT3- phenotype (difference-in-differences -32.6% [95% CI: -55.3%, -9.9%]); (ii) changes in species composition that reflected microbiome maturation (difference-in-differences -68.1% [95% CI: -99.0%, -28.5%); and (iii) greater relative abundance of B. longum (differences-in-differences 49.1% [95% CI: 26.6%, 73.6%]). The dominant strains of B. longum when the intervention started were most similar to the proficient milk oligosaccharide utilizer subspecies infantis, which decreased with infant age and differed by mother-infant FUT2+/FUT3- phenotypes. INTERPRETATION: These findings indicate that a persistently "younger" microbiome at initiation of the intervention reduced its benefits on stunting in areas with a high prevalence of growth restriction. FUNDING: Bill and Melinda Gates Foundation, UK DFID/Aid, Wellcome Trust, Swiss Agency for Development and Cooperation, US National Institutes of Health, UNICEF, and Nutricia Research Foundation.

Terminal α1,2-fucosylation of glycosphingolipids by FUT1 is a key regulator in early cell-fate decisions.

The embryonic cell surface is rich in glycosphingolipids (GSLs), which change during differentiation. The reasons for GSL subgroup variation during early embryogenesis remain elusive. By combining genomic approaches, flow cytometry, confocal imaging, and transcriptomic data analysis, we discovered that α1,2-fucosylated GSLs control the differentiation of human pluripotent cells (hPCs) into germ layer tissues. Overexpression of α1,2-fucosylated GSLs disrupts hPC differentiation into mesodermal lineage and reduces differentiation into cardiomyocytes. Conversely, reducing α1,2-fucosylated groups promotes hPC differentiation and mesoderm commitment in response to external signals. We find that bone morphogenetic protein 4 (BMP4), a mesodermal gene inducer, suppresses α1,2-fucosylated GSL expression. Overexpression of α1,2-fucosylated GSLs impairs SMAD activation despite BMP4 presence, suggesting α-fucosyl end groups as BMP pathway regulators. Additionally, the absence of α1,2-fucosylated GSLs in early/late mesoderm and primitive streak stages in mouse embryos aligns with the hPC results. Thus, α1,2-fucosylated GSLs may regulate early cell-fate decisions and embryo development by modulating cell signaling.

RIP3 regulates doxorubicin-induced intestinal mucositis via FUT2-mediated α-1,2-fucosylation.

OBJECTIVE: Intestinal mucositis is one of the common side effects of anti-cancer chemotherapy. However, the molecular mechanisms involved in mucositis development remain incompletely understood. In this study, we investigated the function of receptor-interacting protein kinase 3 (RIP3/RIPK3) in regulating doxorubicin-induced intestinal mucositis and its potential mechanisms. METHODS: Intestinal mucositis animal models were induced in mice for in vivo studies. Rat intestinal cell line IEC-6 was used for in vitro studies. RNA­seq was used to explore the transcriptomic changes in doxorubicin-induced intestinal mucositis. Intact glycopeptide characterization using mass spectrometry was applied to identify α-1,2-fucosylated proteins associated with mucositis. RESULTS: Doxorubicin treatment increased RIP3 expression in the intestine and caused severe intestinal mucositis in the mice, depletion of RIP3 abolished doxorubicin-induced intestinal mucositis. RIP3-mediated doxorubicin-induced mucositis did not depend on mixed lineage kinase domain-like (MLKL) but on α-1,2-fucosyltransferase 2 (FUT2)-catalyzed α-1,2-fucosylation on inflammation-related proteins. Deficiency of MLKL did not affect intestinal mucositis, whereas inhibition of α-1,2-fucosylation by 2-deoxy-D-galactose (2dGal) profoundly attenuated doxorubicin-induced inflammation and mucositis. CONCLUSIONS: RIP3-FUT2 pathway is a central node in doxorubicin-induced intestinal mucositis. Targeting intestinal RIP3 and/or FUT2-mediated α-1,2-fucosylation may provide potential targets for preventing chemotherapy-induced intestinal mucositis.

Correlation of FUT3 and FUT6 Gene Polymorphisms With Helicobacter pylori Infection.

BACKGROUND: Helicobacter pylori infection is a significant pathogen in gastrointestinal diseases. Previous studies have identified single-nucleotide polymorphisms (SNPs) are factors associated with H. pylori infection. Notably, Leb and Sialyl-Lex antigens, regulated by the FUT3 and FUT6 genes, play a crucial role in H. pylori infection. This study aimed to investigate the correlation between FUT3 and FUT6 gene polymorphisms and H. pylori infection in the Han population of northern China. MATERIALS AND METHODS: An immunoturbidimetric assay was employed to detect H. pylori infection, categorizing subjects into infected and noninfected groups. Gene variants were identified through sequencing. Finally, FUT3 and FUT6 gene polymorphisms were analyzed to assess their association with H. pylori infection. RESULTS: The frequency of the T allele (rs778805) and the G allele (rs61147939) in the infection group was significantly higher than that in the noninfection group (63.4% vs. 55.1%, p = 0.045; 55.2% vs. 47.0%, p = 0.042, respectively). In the infection group, the frequency of the AA genotype (rs3745635) in the recessive model, the TT genotype (rs778805) in the recessive model, and the GG genotype (rs61147939) in the recessive model were significantly higher than the noninfection group (5.8% vs. 2.3%, p = 0.042; 41.9% vs. 29.3%, p = 0.022; 34.9% vs. 20.5%, p = 0.0068, respectively). The frequency of the A13 haplotype and the A13/A13 diplotype of the FUT6 gene was significantly higher in the infection group than in the noninfection group (55.56% vs. 46.32%, p = 0.019; 34.94% vs. 20.30%, p = 0.045, respectively). The rs778805-rs17855739-rs28362459-rs3745635 combination was identified as the best interaction model (p < 0.05). CONCLUSIONS: This study suggests that FUT3 and FUT6 gene polymorphisms are significantly associated with H. pylori infection in the Han Chinese from northern China.

Association of fucosyltransferase 2 gene polymorphism with the susceptibility to norovirus infection in Han Chinese population.

Fucosyltransferase 2 (FUT2) gene, which regulates the formation of Histoblood group antigens, could determine the human susceptibility to norovirus. This study aimed to investigate the correlation between FUT2 gene polymorphism and susceptibility to norovirus gastroenteritis in Han Chinese population. A total of 212 children patients with acute gastroenteritis were enrolled. The stool and serum samples were collected respectively. We used the qPCR method to detect the norovirus infection status from the stool samples, and we used serum samples to detect the FUT2 polymorphism. A case-control study was conducted to investigate the three common SNPs polymorphisms (rs281377, rs1047781, and rs601338) of FUT2 gene with sanger sequencing method. The results indicated that the homozygous genotypes and mutant allele of rs1047781 (A385T) would downgrade the risk of norovirus gastroenteritis in Chinese Han population (AA vs. TT, odds ratio [OR] = 0.098, 95% confidence interval [CI] = 0.026-0.370, p = 0.001; AA + AT vs. TT, OR = 0.118. 95% CI = 0.033-0.424, p = 0.001; A vs. T, OR = 0.528, 95% CI = 0.351-0.974, p = 0.002). There were no significant difference of rs281377 (C357T) and rs601338 (G428A) polymorphisms between norovirus positive and norovirus negative groups (p > 0.05). The haplotype T-T-G was less susceptible (OR = 0.49, 95% CI = 0.31-0.79, p = 0.0034) to norovirus infection compared to other haplotypes. Our results investigated the relationship between the FUT2 gene polymorphisms and norovirus susceptibility in Han Chinese population, and firstly revealed that children with homozygous genotypes and mutant alleles of FUT2 rs1047781 (A385T) were less susceptible to norovirus gastroenteritis.

Analysis of endogenous NOTCH1 from POFUT1 S162L patient fibroblasts reveals the importance of the O-fucose modification on EGF12 in human development.

NOTCH1 is a transmembrane receptor interacting with membrane-tethered ligands on opposing cells that mediate the direct cell-cell interaction necessary for many cell fate decisions. Protein O-fucosyltransferase 1 (POFUT1) adds O-fucose to Epidermal Growth Factor (EGF)-like repeats in the NOTCH1 extracellular domain, which is required for trafficking and signaling activation. We previously showed that POFUT1 S162L caused a 90% loss of POFUT1 activity and global developmental defects in a patient; however, the mechanism by which POFUT1 contributes to these symptoms is still unclear. Compared to controls, POFUT1 S162L patient fibroblast cells had an equivalent amount of NOTCH1 on the cell surface but showed a 60% reduction of DLL1 ligand binding and a 70% reduction in JAG1 ligand binding. To determine if the reduction of O-fucose on NOTCH1 in POFUT1 S162L patient fibroblasts was the cause of these effects, we immunopurified endogenous NOTCH1 from control and patient fibroblasts and analyzed O-fucosylation using mass spectral glycoproteomics methods. NOTCH1 EGF8 to EGF12 comprise the ligand binding domain, and O-fucose on EGF8 and EGF12 physically interact with ligands to enhance affinity. Glycoproteomics of NOTCH1 from POFUT1 S162L patient fibroblasts showed WT fucosylation levels at all sites analyzed except for a large decrease at EGF9 and the complete absence of O-fucose at EGF12. Since the loss of O-fucose on EGF12 is known to have significant effects on NOTCH1 activity, this may explain the symptoms observed in the POFUT1 S162L patient.

BMSCs promote alveolar epithelial cell autophagy to reduce pulmonary fibrosis by inhibiting core fucosylation modifications.

BACKGROUND: Idiopathic pulmonary fibrosis (PF) is a chronic progressive interstitial lung disease characterized by alveolar epithelial cell (AEC) injury and fibroblast activation. Inadequate autophagy in AECs may result from the activation of several signaling pathways following AEC injury, with glycoproteins serving as key receptor proteins. The core fucosylation (CF) modification in glycoproteins is crucial. Mesenchymal stem cells derived from bone marrow (BMSCs) have the ability to regenerate damaged tissue and treat PF. This study aimed to elucidate the relationship and mechanism of interaction between BMSCs, CF modification, and autophagy in PF. METHODS: C57BL/6 male mice, AEC-specific FUT8 conditional knockout (CKO) mice, and MLE12 cells were administered bleomycin (BLM), FUT8 siRNA, and mouse BMSCs, respectively. Experimental techniques including tissue staining, Western blotting, immunofluorescence, autophagic flux detection, and flow cytometry were used in this study. RESULTS: First, we found that autophagy was inhibited while FUT8 expression was elevated in PF mice and BLM-induced AEC injury models. Subsequently, CKO mice and MLE12 cells transfected with FUT8 siRNA were used to demonstrate that inhibition of CF modification induces autophagy in AECs and mitigates PF. Finally, mouse BMSCs were used to demonstrate that they alleviate the detrimental autophagy of AECs by inhibiting CF modification and decreasing PF. CONCLUSIONS: Suppression of CF modification enhanced the suppression of AEC autophagy and reduced PF in mice. Additionally, through the prevention of CF modification, BMSCs can assist AECs deficient in autophagy and partially alleviate PF.

Genetic variation of FUT3 gene in the Han population from Northern China.

BACKGROUND AND OBJECTIVES: The FUT3 gene encodes α(1,3/1,4)-fucosyltransferase, which is a crucial enzyme in the synthesis of Lewis antigens. FUT3 gene variants show race-specific differences. In this study, we conducted a systematic sequence analysis of the FUT3 coding sequence. The objective was to explore genetic variations of the FUT3 gene within the Han population of Northern China. MATERIALS AND METHODS: A cohort of 313 blood donors was recruited for the study. The coding sequence of the FUT3 gene was amplified using polymerase chain reaction, followed by sequencing and haplotype construction. RESULTS: Twelve single nucleotide variations (SNVs) were identified within the coding sequence of the FUT3 gene. Notably, the c.59 T > G site exhibited the highest mutation frequency of 43.13%, followed by the c.508G > A and c.1067 T > A sites with mutation frequencies of 27.48% and 16.93%, respectively. Le was the most common haplotype, accounting for 67.57% of the cases, and Le/Le was the most common diplotype, accounting for 46.33% of the cases. The study also highlighted a significant difference in mutation frequencies of FUT3 gene between the Han Chinese of Northern China and the Dai of Xishuangbanna, China, but not the Han Chinese in Beijing in the North and the Southern Han Chinese, emphasising that Han Chinese in Northern China are genetically most distant from Europeans and closest to East Asians. CONCLUSIONS: Our study characterises FUT3 gene variations in Han Chinese from Northern China, and provides basic genetic data for genetics, forensic medicine, and genotyping of Lewis blood groups.

Core fucosylation within the Fc-FcγR degradation pathway promotes enhanced IgG levels via exogenous L-fucose.

α1,6-Fucosyltransferase (Fut8) is the enzyme responsible for catalyzing core fucosylation. Exogenous L-fucose upregulates fucosylation levels through the GDP-fucose salvage pathway. This study investigated the relationship between core fucosylation and immunoglobulin G (IgG) amounts in serum utilizing WT (Fut8+/+), Fut8 heterozygous knockout (Fut8+/-), and Fut8 knockout (Fut8-/-) mice. The IgG levels in serum were lower in Fut8+/- and Fut8-/- mice compared with Fut8+/+ mice. Exogenous L-fucose increased IgG levels in Fut8+/- mice, while the ratios of core fucosylated IgG versus total IgG showed no significant difference among Fut8+/+, Fut8+/-, and Fut8+/- mice treated with L-fucose. These ratios were determined by Western blot, lectin blot, and mass spectrometry analysis. Real-time PCR results demonstrated that mRNA levels of IgG Fc and neonatal Fc receptor, responsible for protecting IgG turnover, were similar among Fut8+/+, Fut8+/-, and Fut8+/- mice treated with L-fucose. In contrast, the expression levels of Fc-gamma receptor Ⅳ (FcγRⅣ), mainly expressed on macrophages and neutrophils, were increased in Fut8+/- mice compared to Fut8+/+ mice. The effect was reversed by administrating L-fucose, suggesting that core fucosylation primarily regulates the IgG levels through the Fc-FcγRⅣ degradation pathway. Consistently, IgG internalization and transcytosis were suppressed in FcγRⅣ-knockout cells while enhanced in Fut8-knockout cells. Furthermore, we assessed the expression levels of specific antibodies against ovalbumin and found they were downregulated in Fut8+/- mice, with potential recovery observed with L-fucose administration. These findings confirm that core fucosylation plays a vital role in regulating IgG levels in serum, which may provide insights into a novel mechanism in adaptive immune regulation.

Application of the CRISPR/Cas9 Gene Editing Method for Modulating Antibody Fucosylation in CHO Cells.

Genetic engineering plays an essential role in the development of cell lines for biopharmaceutical manufacturing. Advanced gene editing tools can improve both the productivity of recombinant cell lines as well as the quality of therapeutic antibodies. Antibody glycosylation is a critical quality attribute for therapeutic biologics because the glycan patterns on the antibody fragment crystallizable (Fc) region can alter its clinical efficacy and safety as a therapeutic drug. As an example, recombinant antibodies derived from Chinese hamster ovary (CHO) cells are generally highly fucosylated; the absence of α1,6-fucose significantly enhances antibody-dependent cell-mediated cytotoxicity (ADCC) against cancer cells. This chapter describes a protocol applying clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (Cas9) approach with different formats to disrupt the α-1,6-fucosyltransferase (FUT8) gene and subsequently inhibit α-1,6 fucosylation on antibodies expressed in CHO cells.

Combinatorial Engineering of Escherichia coli for Enhancing 3-Fucosyllactose Production.

3-Fucosyllactose (3-FL) is an important fucosylated human milk oligosaccharide (HMO) with biological functions such as promoting immunity and brain development. Therefore, the construction of microbial cell factories is a promising approach to synthesizing 3-FL from renewable feedstocks. In this study, a combinatorial engineering strategy was used to achieve efficient de novo 3-FL production in Escherichia coli. α-1,3-Fucosyltransferase (futM2) from Bacteroides gallinaceum was introduced into E. coli and optimized to create a 3-FL-producing chassis strain. Subsequently, the 3-FL titer increased to 5.2 g/L by improving the utilization of the precursor lactose and down-regulating the endogenous competitive pathways. Furthermore, a synthetic membraneless organelle system based on intrinsically disordered proteins was designed to spatially regulate the pathway enzymes, producing 7.3 g/L 3-FL. The supply of the cofactors NADPH and GTP was also enhanced, after which the 3-FL titer of engineered strain E26 was improved to 8.2 g/L in a shake flask and 10.8 g/L in a 3 L fermenter. In this study, we developed a valuable approach for constructing an efficient 3-FL-producing cell factory and provided a versatile workflow for other chassis cells and HMOs.