Genetic Analysis of Two Novel GPI Variants Disrupting H Bonds and Localization Characteristics of 55 Gene Variants Associated with Glucose-6-phosphate Isomerase Deficiency.

OBJECTIVE: Glucose-6-phosphate isomerase (GPI) deficiency is a rare hereditary nonspherocytic hemolytic anemia caused by GPI gene variants. This disorder exhibits wide heterogeneity in its clinical manifestations and molecular characteristics, often posing challenges for precise diagnoses using conventional methods. To this end, this study aimed to identify the novel variants responsible for GPI deficiency in a Chinese family. METHODS: The clinical manifestations of the patient were summarized and analyzed for GPI deficiency phenotype diagnosis. Novel compound heterozygous variants of the GPI gene, c.174C>A (p.Asn58Lys) and c.1538G>T (p.Trp513Leu), were identified using whole-exome and Sanger sequencing. The AlphaFold program and Chimera software were used to analyze the effects of compound heterozygous variants on GPI structure. RESULTS: By characterizing 53 GPI missense/nonsense variants from previous literature and two novel missense variants identified in this study, we found that most variants were located in exons 3, 4, 12, and 18, with a few localized in exons 8, 9, and 14. This study identified novel compound heterozygous variants associated with GPI deficiency. These pathogenic variants disrupt hydrogen bonds formed by highly conserved GPI amino acids. CONCLUSION: Early family-based sequencing analyses, especially for patients with congenital anemia, can help increase diagnostic accuracy for GPI deficiency, improve child healthcare, and enable genetic counseling.

Glucose phosphate isomerase deficiency demasked by whole-genome sequencing: a case report.

BACKGROUND: Glucose-6-phosphate isomerase deficiency is a rare genetic disorder causing hereditary nonspherocytic hemolytic anemia. It is the second most common glycolytic enzymopathy in red blood cells. About 90 cases are reported worldwide, with symptoms including chronic hemolytic anemia, jaundice, splenomegaly, gallstones, cholecystitis, and in severe cases, neurological impairments, hydrops fetalis, and neonatal death. CASE PRESENTATION: This paper details the case of the first Danish patient diagnosed with glucose-6-phosphate isomerase deficiency. The patient, a 27-year-old white female, suffered from lifelong anemia of unknown origin for decades. Diagnosis was established through whole-genome sequencing, which identified two GPI missense variants: the previously documented variant p.(Thr224Met) and a newly discovered variant p.(Tyr341Cys). The pathogenicity of these variants was verified enzymatically. CONCLUSIONS: Whole-genome sequencing stands as a potent tool for identifying hereditary anemias, ensuring optimal management strategies.

Production of D-glucaric acid with phosphoglucose isomerase-deficient Saccharomyces cerevisiae.

D-Glucaric acid is a potential biobased platform chemical. Previously mainly Escherichia coli, but also the yeast Saccharomyces cerevisiae, and Pichia pastoris, have been engineered for conversion of D-glucose to D-glucaric acid via myo-inositol. One reason for low yields from the yeast strains is the strong flux towards glycolysis. Thus, to decrease the flux of D-glucose to biomass, and to increase D-glucaric acid yield, the four step D-glucaric acid pathway was introduced into a phosphoglucose isomerase deficient (Pgi1p-deficient) Saccharomyces cerevisiae strain. High D-glucose concentrations are toxic to the Pgi1p-deficient strains, so various feeding strategies and use of polymeric substrates were studied. Uniformly labelled 13C-glucose confirmed conversion of D-glucose to D-glucaric acid. In batch bioreactor cultures with pulsed D-fructose and ethanol provision 1.3 g D-glucaric acid L-1 was produced. The D-glucaric acid titer (0.71 g D-glucaric acid L-1) was lower in nitrogen limited conditions, but the yield, 0.23 g D-glucaric acid [g D-glucose consumed]-1, was among the highest that has so far been reported from yeast. Accumulation of myo-inositol indicated that myo-inositol oxygenase activity was limiting, and that there would be potential to even higher yield. The Pgi1p-deficiency in S. cerevisiae provides an approach that in combination with other reported modifications and bioprocess strategies would promote the development of high yield D-glucaric acid yeast strains.

RHBDF1 deficiency suppresses melanoma glycolysis and enhances efficacy of immunotherapy by facilitating glucose-6-phosphate isomerase degradation via TRIM32.

Melanoma is a dangerous form of skin cancer, making it important to investigate new mechanisms and approaches to enhance the effectiveness of treatment. Here, we establish a positive correlation between the human rhomboid family-1 (RHBDF1) protein and melanoma malignancy. We demonstrate that the melanoma RHBDF1 decrease dramatically inhibits tumor growth and the development of lung metastases, which may be related to the impaired glycolysis. We show that RHBDF1 function is essential to the maintenance of high levels of glycolytic enzymes, especially glucose-6-phosphate isomerase (GPI). Additionally, we discover that the E3 ubiquitin ligase tripartite motif-containing 32 (TRIM32) mediates the K27/K63-linked ubiquitination of GPI and the ensuing lysosomal degradation process. We prove that the multi-transmembrane domain of RHBDF1 is in competition with GPI, preventing the latter from interacting with NCL1-HT2A-LIN41 (NHL) domain of TRIM32. We also note that the mouse RHBDF1's R747 and Y799 are crucial for competitive binding and GPI protection. Artificially silencing the Rhbdf1 gene in a mouse melanoma model results in declined lactic acid levels, elevated cytotoxic lymphocyte infiltration, and improved tumor responsiveness to immunotherapy. These results provide credence to the hypothesis that RHBDF1 plays a significant role in melanoma regulation and suggest that blocking RHBDF1 may be an efficient technique for reestablishing the tumor immune microenvironment (TIME) in melanoma and halting its progression.

High-resolution melting (HRM)-based detection of polymorphisms in the malic enzyme and glucose-6-phosphate isomerase genes for Leishmania infantum genotyping.

BACKGROUND: Leishmaniasis is a zoonotic disease endemic in the Mediterranean region where Leishmania infantum is the causative agent of human and canine infection. Characterization of this parasite at the subspecies level can be useful in epidemiological studies, to evaluate the clinical course of the disease (e.g. resistant strains, visceral and cutaneous forms of leishmaniasis) as well as to identify infection reservoirs. Multilocus enzyme electrophoresis (MLEE), a method currently recognized as the reference method for characterizing and identifying strains of Leishmania, is cumbersome and time-consuming and requires cultured parasites. These disadvantages have led to the development of other methods, such as multilocus microsatellite typing (MLMT) and multilocus sequence typing (MLST), for typing Leishmania parasites; however, these methods have not yet been applied for routine use. In this study, we first used MLST to identify informative polymorphisms on single-copy genes coding for metabolic enzymes, following which we developed two rapid genotyping assays based on high-resolution melting (HRM) analysis to explore these polymorphisms in L. infantum parasites. METHODS: A customized sequencing panel targeting 14 housekeeping genes was designed and MLST analysis was performed on nine L. infantum canine and human strains/isolates. Two quantitative real-time PCR-HRM assays were designed to analyze two informative polymorphisms on malic enzyme (ME) and glucose-6-phosphate isomerase (GPI) genes (390T/G and 1831A/G, respectively). The two assays were applied to 73 clinical samples/isolates from central/southern Italy and Pantelleria island, and the results were confirmed by DNA sequencing in a subset of samples. RESULTS: The MLST analysis, together with sequences available in the Genbank database, enabled the identification of two informative polymorphisms on the genes coding for ME and GPI. The fast screening of these polymorphisms using two HRM-based assays in 73 clinical samples/isolates resulted in the identification of seven genotypes. Overall, genotype 1 (sequence type 390T/1831G) was the most highly represented (45.2%) in the overall sample and correlated with the most common L. infantum zymodemes (MON-1, MON-72). Interestingly, in Pantelleria island, the most prevalent genotype (70.6%) was genotype 6 (sequence type 390T/1831A). CONCLUSIONS: Applying our HRM assays on clinical samples allowed us to identify seven different genotypes without the need for parasite isolation and cultivation. We have demonstrated that these assays could be used as fast, routine and inexpensive tools for epidemiological surveillance of L. infantum or for the identification of new infection reservoirs.

The novel compound heterozygous variants identified in a Chinese family with glucose phosphate isomerase deficiency and pathogenicity analysis.

BACKGROUND AND AIMS: Glucose phosphate isomerase (GPI) deficiency is an extremely rare autosomal recessive disorder caused by mutations in the GPI gene. In this research, the proband displaying typical manifestations of haemolytic anaemia and his family members were recruited to analyse the pathogenicity of the detected variants. METHODS: Peripheral blood samples were collected from the family members and genomic DNA was extracted and targeted for capture and sequencing. The effect of the candidate pathogenic variants on splicing was further investigated using the minigene splicing system. The computer simulation was also used for further analysis of the detected data. RESULTS: The proband carried the compound heterozygous variants c.633 + 3 A > G and c.295G > T in the GPI gene, which have never been reported before. In the genealogy, co-segregation of the mutant genotype with the phenotype was established. The minigene study showed that intronic mutations resulted in abnormal pre-mRNA splicing. Specifically, the two aberrant transcripts: r.546_633del and r.633 + 1_633 + 2insGT were transcribed by the minigene plasmid expressing the c.633 + 3 A > G variant. The missense mutation c.295G > T in exon 3 resulted in altering glycine at codon 87 to cysteine which was predicted to be pathogenic in an in silico analysis. Deeper analyses revealed that the Gly87Cys missense mutation led to steric hindrance. Compared to the wild-type, the mutation G87C led to a significant increase in intermolecular forces. CONCLUSION: Overall, the novel compound heterozygous variants in the GPI gene contributed to the etiology of the disease. Genetic testing can assist in the diagnosis. The novel gene variants identified in the present study has further expanded the mutational spectrum of GPI deficiency, which can better guide family counselling.

A Novel Glucose-6-Phosphate Isomerase Exists in Chicken Breast Meat: A Selenium-Containing Enzyme that Should Be Re-recognized Through New Eyes.

Glucose-6-phosphate isomerase (GPI) is a highly conserved glycolytic enzyme in nature, and less information was available for GPI from hens. In this study a newly discovered selenocysteine (Sec)-containing GPI in common chicken breast meat was first isolated, purified and identified. Data about LC-MS/MS, FTIR and Se species analyses show that the molecular weight of the enzyme is 62,091 Da and only one Sec is inserted at the 403rd position in the highly conserved primary domain SIS_PGI with sugar conversion function. The enzyme shows excellent activity against hydroxyl radicals as vitamin C (Vc) in vitro. It is deduced that the Sec-containing GPI in the chicken meat may depend on Sec in its molecular structure to resist reactive oxygen species (ROS) stress produced by the accompanying biochemical reactions in cells, to protect its stability and maintain its efficient function that catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate in the critical glycolytic pathway.

Cytosolic phosphoglucose isomerase is essential for microsporogenesis and embryogenesis in Arabidopsis.

Phosphoglucose isomerase (PGI) catalyzes the interconversion of fructose-6-phosphate and glucose-6-phosphate, which impacts cell carbon metabolic flow. Arabidopsis (Arabidopsis thaliana) contains two nuclear PGI genes respectively encoding plastidial PGI1 and cytosolic PGI (cPGI). The loss of PGI1 impairs the conversion of F6P of the Calvin-Benson cycle to G6P for the synthesis of transitory starch in leaf chloroplasts. Since cpgi knockout mutants have not yet been obtained, they are thought to be lethal. The cpgi lethality can be rescued by expressing CaMV 35S promoter (p35S)-driven cPGI; however, the complemented line is completely sterile due to pollen degeneration. Here, we generated a cpgi mutant expressing p35S::cPGI-YFP in which YFP fluorescence in developing anthers was undetectable specifically in the tapetum and in pollen, which could be associated with male sterility. We also generated RNAi-cPGI knockdown lines with strong cPGI repression in floral buds that exhibited reduced male fertility due to the degeneration of most pollen. Histological analyses indicated that the synthesis of intersporal callose walls was impaired, causing microsporocytes to fail to separate haploid daughter nuclei to form tetrads, which might be responsible for subsequent pollen degeneration. We successfully isolated cpgi knockout mutants in the progeny of a heterozygous cpgi mutant floral-dipped with sugar solutions. The rescued cpgi mutants exhibited diminished young vegetative growth, reduced female fertility, and impaired intersporal callose wall formation in a meiocyte, and, thus, male sterility. Collectively, our data suggest that cPGI plays a vital role in carbohydrate partitioning, which is indispensable for microsporogenesis and early embryogenesis.

Three amino acid substitutions contributing to thermostability of phosphoglucose isomerase in the Glanville fritillary butterfly.

Temperature is one of the most important environmental factors that affect organisms, especially ectotherms, due to its effects on protein stability. Understanding the general rules that govern thermostability changes in proteins to adapt high-temperature environments is crucial. Here, we report the amino acid substitutions of phosphoglucose isomerase (PGI) related to thermostability in the Glanville fritillary butterfly (Melitaea cinxia, Lepidoptera: Nymphalidae). The PGI encoded by the most common allele in M. cinxia in the Chinese population (G3-PGI), which is more thermal tolerant, is more stable under heat stress than that in the Finnish population (D1-PGI). There are 5 amino acid substitutions between G3-PGI and D1-PGI. Site-directed mutagenesis revealed that the combination of amino acid substitutions of H35Q, M49T, and I64V may increase PGI thermostability. These substitutions alter the 3D structure to increase the interaction between 2 monomers of PGI. Through molecular dynamics simulations, it was found that the amino acid at site 421 is more stable in G3-PGI, confining the motion of the α-helix 420-441 and stabilizing the interaction between 2 PGI monomers. The strategy for high-temperature adaptation through these 3 amino acid substitutions is also adopted by other butterfly species (Boloria eunomia, Aglais urticae, Colias erate, and Polycaena lua) concurrent with M. cinxia in the Tianshan Mountains of China, i.e., convergent evolution in butterflies.

Glucose 6 Phosphate Isomerase Deficiency, a Rare Hemolytic Anemia Misdiagnosed as Hereditary Spherocytosis.

Hereditary hemolytic anemias are a heterogenous group of disorders that include membranopathies, enzymopathies, and hemoglobinopathies. Genetic testing is helpful in the diagnostic workup when the clinical and laboratory workup is not conclusive. Here, we present a case of a 21-month-old female who was initially diagnosed with hereditary spherocytosis based on the presence of a variant of unknown significance in the SPTB gene. Further genetic workup revealed a homozygous glucose 6 phosphate isomerase mutation and the patient was ultimately diagnosed with glucose 6 phosphate isomerase deficiency.

Using phosphoglucose isomerase-deficient (pgi1Δ) Saccharomyces cerevisiae to map the impact of sugar phosphate levels on D-glucose and D-xylose sensing.

BACKGROUND: Despite decades of engineering efforts, recombinant Saccharomyces cerevisiae are still less efficient at converting D-xylose sugar to ethanol compared to the preferred sugar D-glucose. Using GFP-based biosensors reporting for the three main sugar sensing routes, we recently demonstrated that the sensing response to high concentrations of D-xylose is similar to the response seen on low concentrations of D-glucose. The formation of glycolytic intermediates was hypothesized to be a potential cause of this sensing response. In order to investigate this, glycolysis was disrupted via the deletion of the phosphoglucose isomerase gene (PGI1) while intracellular sugar phosphate levels were monitored using a targeted metabolomic approach. Furthermore, the sugar sensing of the PGI1 deletants was compared to the PGI1-wildtype strains in the presence of various types and combinations of sugars. RESULTS: Metabolomic analysis revealed systemic changes in intracellular sugar phosphate levels after deletion of PGI1, with the expected accumulation of intermediates upstream of the Pgi1p reaction on D-glucose and downstream intermediates on D-xylose. Moreover, the analysis revealed a preferential formation of D-fructose-6-phosphate from D-xylose, as opposed to the accumulation of D-fructose-1,6-bisphosphate that is normally observed when PGI1 deletants are incubated on D-fructose. This may indicate a role of PFK27 in D-xylose sensing and utilization. Overall, the sensing response was different for the PGI1 deletants, and responses to sugars that enter the glycolysis upstream of Pgi1p (D-glucose and D-galactose) were more affected than the response to those entering downstream of the reaction (D-fructose and D-xylose). Furthermore, the simultaneous exposure to sugars that entered upstream and downstream of Pgi1p (D-glucose with D-fructose, or D-glucose with D-xylose) resulted in apparent synergetic activation and deactivation of the Snf3p/Rgt2p and cAMP/PKA pathways, respectively. CONCLUSIONS: Overall, the sensing assays indicated that the previously observed D-xylose response stems from the formation of downstream metabolic intermediates. Furthermore, our results indicate that the metabolic node around Pgi1p and the level of D-fructose-6-phosphate could represent attractive engineering targets for improved D-xylose utilization.

GPI: An indicator for immune infiltrates and prognosis of human breast cancer from a comprehensive analysis.

Glucose-6-phosphate isomerase (GPI) plays an important part in gluconeogenesis and glycolysis through the interconversion of d-glucose-6-phosphate and d-fructose-6-phosphate, and its clinical significance still remains unclear in breast cancer (BRCA). We analyzed the expressions of GPI in BRCA patients to determine prognostic values. Our results showed that the expression levels of GPI were upregulated in BRCA patients, and a high GPI expression is correlated with poor overall survival (OS) in BRCA. At the same time, a high GPI expression is correlated with poor clinicopathological characteristics, such as stage III, over 60 years old, N3, HER2 negative, and estrogen receptor (ER) positive. Further analysis of the influence of GPI on the prognosis of BRCA suggested that 50 genes and 10 proteins were positively correlated with GPI, and these genes and proteins were mainly involved in cell cycle signaling pathways. In addition, in this study, we observed that GPI was closely related to N 6-methyladenosine (m6A) RNA methylation modification and immune cell infiltration and ferroptosis-related gene expression in BRCA, and there was a difference in m6A RNA methylation alterations, immune cell infiltration, and ferroptosis-related gene expression between the high GPI expression group and the low GPI expression group. Finally, we found that GPI in BRCA had 2.6% gene alterations, and BRCA patients with gene alteration of GPI had a poor prognosis in disease-free survival (DFS). Altogether, our work strongly suggested that GPI may serve as a new prognostic biomarker for BRCA patients.

A structural basis for the functional differences between the cytosolic and plastid phosphoglucose isomerase isozymes.

Phosphoglucose isomerase (PGI) catalyzes the interconversion between glucose-6-phosphate (G6P) and fructose-6-phosphate (F6P), thereby regulating sucrose synthesis in plant cells. In general, plants contain a pair of PGI isozymes located in two distinct compartments of the cell (cytosol and plastid) with differences in both the primary structure and the higher-order structure. Previously, we showed that the activity of cytosolic PGI (PGIc) is more robust (activity, thermal stability, substrate turnover rate, etc.) than that of the plastid counterpart (PGIp) in multiple organisms, including wheat, rice, and Arabidopsis. The crystal structures of apoTaPGIc (an isotype cytosol PGIc in Triticum aestivum), TaPGIc-G6P complex, and apoTaPGIp (an isotype plastid PGIp in Triticum aestivum) were first solved in higher plants, especially in crops. In this study, we detailed the structural characteristics related to the biochemical properties and functions of TaPGIs in different plant organelles. We found that the C-terminal domains (CTDs) of TaPGIc and TaPGIp are very different, which affects the stability of the dimerized enzyme, and that Lys213TaPGIc/Lys193TaPGIp and its surrounding residues at the binding pocket gateway may participate in the entrance and exit of substrates. Our findings provide a good example illuminating the evolution of proteins from primary to higher structures as a result of physical barriers and adaptation to the biochemical environment.

Co-culture with osteoblasts up-regulates glycolysis of chondrocytes through MAPK/HIF-1 pathway.

It is well recognized that the neighbor location between cartilage layer and subchondral bone facilitates the intercellular communication and material exchange. However, the evidence that demonstrates the influence of direct communication between cartilage and subchondral bone on their cell behaviors are still partially unknown. In the current study, we established a co-culture system of chondrocytes and osteoblasts aiming to explore the changes of intracellular metabolism of chondrocytes induced by osteoblasts. By using lactate assay kit, RNA sequencing, qRT-PCR and western blot, we found that osteoblasts enhanced the glycolysis in chondrocytes by characterizing the changes of lactate secretion and cytoplasmic expression, and gene expressions including glucose-6-phosphate isomerase 1 (Gpi1), phosphofructokinase, liver type (Pfkl), lactate dehydrogenase A (Ldha), aldolase, fructose-bisphosphate C (Aldoc), phosphoglycerate kinase 1 (Pgk1), glyceraldehyde-3-phosphate dehydrogenase (Gapdh) and triosephosphate isomerase 1 (Tpi1). The enhanced glycolysis might be due to the activation of HIF-1 signaling and its downstream target, pyruvate dehydrogenase kinase1 (PDK1), by qRT-PCR, western blot and immunofluorescence. We also detected the up-regulation of ERK and p38/MAPK upstream signaling in chondrocytes induced by osteoblasts by western blot and immunofluorescence. The enhanced glycolysis in chondrocytes induced by osteoblasts could help us to better understand the intracellular metabolic mechanism of chondrocytes and cartilage disease occurrence.

Hereditary nonspherocytic hemolytic anemia caused by glucose-6-phosphate isomerase (GPI) deficiency in a Chinese patient: a case report.

BACKGROUND: Glucose phosphate isomerase (GPI) deficiency is a rare autosomal recessive disorder that causes hereditary nonspherocytic hemolytic anemia (HNSHA). Homozygous or compound heterozygous mutation of the GPI gene on chromosome 19q13 is the cause of GPI deficiency. Fifty-seven GPI mutations have been reported at the molecular level. CASE PRESENTATION: A 5-month-old boy was presented with repeated episodes of jaundice after birth. He suffered from moderate hemolytic anemia (hemoglobin levels ranging from 62 to 91 g/L) associated with macrocytosis, reticulocytosis, neutropenia, and hyperbilirubinemia. Whole-exome sequencing showed that he has a missense mutation c.301G > A (p.Val101Met) in exon 4 and a frameshift mutation c.812delG (p.Gly271Glufs*131) in exon 10. Mutation p.Gly271Glufs*131 is a novel frameshift null mutation in GPI deficiency. CONCLUSION: In a patient with recurrent jaundice since birth, mutations in the GPI gene associated with HNSHA should be evaluated. The c.812delG (p.Gly271Glufs*131) variant may be a novel mutation of the GPI gene. Compound heterozygous mutations c.301G > A (p.Val101Met) and c.812delG (p.Gly271Glufs*131) are not relevant to neurological impairment.

Phosphoglucose Isomerase Is Important for Aspergillus fumigatus Cell Wall Biogenesis.

Aspergillus fumigatus is a devastating opportunistic fungal pathogen causing hundreds of thousands of deaths every year. Phosphoglucose isomerase (PGI) is a glycolytic enzyme that converts glucose-6-phosphate to fructose-6-phosphate, a key precursor of fungal cell wall biosynthesis. Here, we demonstrate that the growth of A. fumigatus is repressed by the deletion of pgi, which can be rescued by glucose and fructose supplementation in a 1:10 ratio. Even under these optimized growth conditions, the Δpgi mutant exhibits severe cell wall defects, retarded development, and attenuated virulence in Caenorhabditis elegans and Galleria mellonella infection models. To facilitate exploitation of A. fumigatus PGI as an antifungal target, we determined its crystal structure, revealing potential avenues for developing inhibitors, which could potentially be used as adjunctive therapy in combination with other systemic antifungals. IMPORTANCE Aspergillus fumigatus is an opportunistic fungal pathogen causing deadly infections in immunocompromised patients. Enzymes essential for fungal survival and cell wall biosynthesis are considered potential drug targets against A. fumigatus. PGI catalyzes the second step of the glycolysis pathway, linking glycolysis and the pentose phosphate pathway. As such, PGI has been widely considered as a target for metabolic regulation and therefore a therapeutic target against hypoxia-related diseases. Our study here reveals that PGI is important for A. fumigatus survival and exhibit pleiotropic functions, including development, cell wall glucan biosynthesis, and virulence. We also solved the crystal structure of PGI, thus providing the genetic and structural groundwork for the exploitation of PGI as a potential antifungal target.

Osteoblasts induce glucose-derived ATP perturbations in chondrocytes through noncontact communication.

Cartilage and subchondral bone communicate with each other through material and signal exchanges. However, direct evidence provided by experimental studies on their interactions is insufficient. In the present study, we establish a noncontact co-culture model with a transwell chamber to explore the energetic perturbations in chondrocytes influenced by osteoblasts. Our results indicate that osteoblasts induce more ATP generation in chondrocytes through an energetic shift characterized by enhanced glycolysis and impaired mitochondrial tricarboxylic acid cycle. Enhanced glycolysis is shown by an increase of secreted lactate and the upregulation of glycolytic enzymes, including glucose-6-phosphate isomerase (Gpi), liver type ATP-dependent 6-phosphofructokinase (Pfkl), fructose-bisphosphate aldolase C (Aldoc), glyceraldehyde-3-phosphate dehydrogenase (Gapdh), triosephosphate isomerase (Tpi1), and phosphoglycerate kinase 1 (Pgk1). Impaired mitochondrial tricarboxylic acid cycle is characterized by the downregulation of cytoplasmic aspartate aminotransferase (Got1) and mitochondrial citrate synthase (Cs). Osteoblasts induce the activation of Akt and P38 signaling to mediate ATP perturbations in chondrocytes. This study may deepen our understanding of the maintenance of metabolic homeostasis in the bone-cartilage unit.

Cloning and characterization of phosphoglucose isomerase in Lentinula edodes.

Phosphoglucose isomerase (PGI) is a key enzyme that participates in polysaccharide synthesis, which is responsible for the interconversion of glucose-6-phosphate (G-6-P) and fructose-6-phosphate (F-6-P), but there is little research focusing on its role in fungi, especially in higher basidiomycetes. The pgi gene was cloned from Lentinula edodes and named lepgi. Then, the lepgi-silenced strains were constructed by RNA interference. In this study, we found that lepgi-silenced strains had significantly less biomass than the wild-type (WT) strain. Furthermore, the extracellular polysaccharide (EPS) and intracellular polysaccharide (IPS) levels increased 1.5- to 3-fold and 1.5-fold, respectively, in lepgi-silenced strains. Moreover, the cell wall integrity in the silenced strains was also altered, which might be due to changes in the compounds and structure of the cell wall. The results showed that compared to WT, silencing lepgi led to a significant decrease of approximately 40% in the ß-1,3-glucan content, and there was a significant increase of 2-3-fold in the chitin content. These findings provide support for studying the biological functions of lepgi in L. edodes.

Clinical, laboratory, and mutational profile of children with glucose phosphate isomerase deficiency: a single centre report.

Glucose phosphate isomerase (GPI) deficiency is an autosomal recessive condition with mutations in the GPI gene on chromosome 19q13.1. Patients present with congenital non-spherocytic hemolytic anemia, and occasionally intellectual disability. In this study, we describe the clinical, hematological and biochemical parameters in the largest single-center cohort consisting of 17 GPI-deficient cases. Demographic and clinical data were noted, and red cell enzyme activity levels were estimated. Mutation analysis was done by single-stranded-conformation polymorphism, restriction-fragment length polymorphism and Sanger's sequencing of exon 12 of the GPI gene. The male-to-female ratio was 0.7:1, median age at diagnosis was 5.0 years, 82.3% of patients had severe neonatal jaundice, and 13.3% had subtle neurological manifestations. Median Hb and MCV levels were 6.3 g/dl and 130.2 fl. Splenectomized patients required fewer transfusions. Sixteen of 17 patients had the pathogenic c.1040G > A (p.Arg347His) homozygous mutation in exon12 of the GPI gene, and one had the pathogenic c.1414C > T(p.Arg472Cys) homozygous mutation in exon 16. In summary, we report that neonatal jaundice, macrocytosis and high prevalence of p.Arg347His variant were predominant in GPI deficiency with prominent lack of neurological manifestations, and we emphasize the benefits of splenectomy and the need for genetic counseling.

Incidence and severity of G6PI-induced arthritis are not increased in genetically distinct mouse strains upon aging.

BACKGROUND: The incidence of rheumatoid arthritis is correlated with age. In this study, we analyzed the association of the incidence and severity of glucose-6-phosphate isomerase (G6PI)-induced arthritis with age in two different mouse strains. METHODS: Young and very old mice from two different arthritis-susceptible wild-type mouse strains were analyzed after a single subcutaneous injection of G6PI s.c. The metabolism and the function of synoviocytes were analyzed in vitro, the production of bioactive lipid mediators by myeloid cells and synoviocytes was assessed in vitro and ex vivo by UPLC-MS-MS, and flow cytometry was used to verify age-related changes of immune cell composition and function. RESULTS: While the severity of arthritis was independent from age, the onset was delayed in old mice. Old mice showed common signs of immune aging like thymic atrophy associated with decreased CD4+ effector T cell numbers. Despite its decrease, the effector T helper (Th) cell compartment in old mice was reactive and functionally intact, and their Tregs exhibited unaltered suppressive capacities. In homeostasis, macrophages and synoviocytes from old mice produced higher amounts of pro-inflammatory cyclooxygenase (COX)-derived products. However, this functional difference did not remain upon challenge in vitro nor upon arthritis reactions ex vivo. CONCLUSION: While old mice show a higher baseline of inflammatory functions, this does not result in increased reaction towards self-antigens in arthritis-susceptible mouse strains. Together, our data from two different mouse strains show that the susceptibility for G6PI-induced arthritis is not age-dependent.