Explore the vast range of titles available.

Two brothers with an undefined congenital disorder of glycosylation were found to have phosphoglucomutase 1 deficiency, which has previously been described as a glycogen storage disorder. Supplementation with galactose improves protein glycosylation in this disease. Protein N-glycosylation is a ubiquitous process in all organ systems. During N-glycosylation, glycan precursors are assembled from monosaccharide units and then covalently attached to asparagine residues in the nascent peptide chain of a protein (Figure 1). The protein-bound glycans undergo further processing to generate mature glycoproteins. Genetic defects in protein N-glycosylation, designated as congenital disorders of glycosylation, lead to multisystem disorders. Mutations of genes involved in N-glycosylation may affect either the biosynthesis of the glycan precursor (congenital disorder of glycosylation type I [CDG-I]) or the processing of the glycan after its attachment to the protein (congenital disorder of glycosylation type . . .

Triple-negative breast cancer (TNBC) is characterized by a pronounced hypoxic tumor microenvironment, with cancer-associated fibroblasts (CAFs) serving as the predominant cellular component and playing crucial roles in regulating tumor progression. However, the mechanism by which CAFs affect the biological behavior of tumor cells in hypoxic environment remain elusive. This study employed a bead-based multiplex immunoassay to analyze a panel of cytokines/chemokines and identified colony stimulating factor 3 (CSF3) as a significantly elevated component in the secretome of hypoxic CAFs. We found that CSF3 promoted the invasive behavior of TNBC cells by activating the downstream signaling pathway of its receptor, CSF3R. RNA sequencing analysis further revealed that phosphoglucomutase 2-like 1 (PGM2L1) is a downstream target of the CSF3/CSF3R signaling, enhancing the glycolysis pathway and providing energy to support the malignant phenotype of breast cancer. In vivo, we further confirmed that CSF3 promotes TNBC progression by targeting PGM2L1. These findings suggest that targeting CSF3/CSF3R may represent a potential therapeutic approach for TNBC.

The placenta plays an essential role facilitating nutrient, gas and waste exchange between the maternal and fetal systems for optimal fetal growth. When placental development is impaired and the placenta dysfunctional, serious pregnancy complications such as fetal growth restriction and preeclampsia may arise. Previously, phosphoglucomutase-5 (PGM5) transcripts were found to be highly elevated in the blood of patients whose pregnancies were complicated by fetal growth restriction and preeclampsia. As both conditions feature placental insufficiency, here we aimed to characterise PGM5 levels in the healthy and dysfunctional placenta. PGM5 expression was detectable in all placental samples across gestation, in cases of preterm preeclampsia, fetal growth restriction and controls. PGM5 mRNA expression was significantly downregulated in the pathological placentas compared to controls, but PGM5 protein production was not dysregulated. Isolated cytotrophoblast and placental explant tissue exposed to hypoxia (modelling placental dysfunction) demonstrated significantly increased PGM5 expression, but again did not change protein levels. Silencing PGM5 expression under hypoxic conditions in primary cytotrophoblast did not alter anti-angiogenic sFLT-1 secretion but increased expression of multiple genes associated with cell growth, apoptosis and oxidative stress, whilst also increasing cell viability. Expression of PGM5 in all placental samples assessed suggests that PGM5 has functions in the placenta. However, further investigation could be performed to explore the discrepancies in protein and mRNA expression, as well as the precise function of PGM5 in the placenta, and whether altered PGM5 levels may be important for placental development.

Background Phosphoglucomutase 3 deficiency (PGM3 deficiency) is a rare congenital disorder of glycosylation classically associated with severe immunodeficiency, skeletal abnormalities, and neurodevelopmental impairment. However, emerging evidence suggests that PGM3 deficiency may also present with attenuated or milder clinical phenotypes. In this study, we describe patients with a novel PGM3 variant exhibiting a less severe immunological and clinical presentation, thereby expanding the known phenotypic spectrum of PGM3 deficiency. Methods Demographic-data and Wechsler Intelligence Scale for Children profiles were evaluated alongside laboratory data, including complete blood cell counts, lymphocyte subsets, serum immunoglobulin levels, vaccine antibody titers, and lymphocyte cytokine profiles. Whole exome sequencing was conducted, and phospho-flow assays were utilized for the analysis of p-STATs. Results Five patients with a mild form of PGM3 deficiency were described, exhibiting a Hyper-IgE Syndrome phenotype without severe skeletal dysplasia or dysmorphism, with the exception of one patient displaying very mild skeletal dysplasia and three patients exhibiting mild to moderate intellectual disability. All patients demonstrated an increase in Natural Killer T cells and a decrease in B cells, alongside an increase in activated CD4 + T cells (CD45RO+), a decrease in naïve CD4 + and CD8 + T cells (CD45RA+ CCR7+), and an increase in TEMRA CD8 + T cells (CD45RA+CCR7–). Functional analysis of all patients revealed impaired PGM3 function, as evidenced by decreased surface expression of gp130 and p-STAT3. Conclusion Defective glycosylation in PGM3 deficiency leads to reduced gp130 expression and attenuated gp130-dependent STAT3 phosphorylation. The resulting cellular features partially overlap with those observed in STAT3 loss-of-function and gp130 deficiency, supporting a shared signaling mechanism while remaining clinically distinct.

In solid tumors, hypoxia can trigger aberrant expression of transcription factors and genes, resulting in abnormal biological functions such as altered energetic pathways in cancer cells. Glucose metabolism is an important part of this phenomenon, which is associated with changes in the functional expression of transporters and enzymes involved in the glycolysis pathway. The latter phenomenon can finally lead to the lactate accumulation and pH dysregulation in the tumor microenvironment and subsequently further invasion and metastasis of cancer cells. Having capitalized on the computational modeling, in this study, for the first time, we aimed to investigate the effects of hypoxia-induced factor-1 (HIF-1) mediated hypoxia on the magnitude of functional expression of all the enzymes and transporters involved in the glycolysis process. The main objective was to establish a quantitative relationship between the hypoxia intensity and the intracellular lactate levels and determine the key regulators of the glycolysis pathway. This model clearly showed an increase in the lactate concentration during the oxygen depletion. The proposed model also predicted that the phosphofructokinase-1 and phosphoglucomutase enzymes might play the most important roles in the regulation of the lactate production.

Phosphoglucomutase (EC 5.4.2.2., PGM), a key enzyme of glycogenolysis and glycogenesis, catalyzes the interconversion of glucose 1-phosphate and glucose 6-phosphate, whereas phosphomannomutase (EC 5.4.2.8., PMM) transfers the phosphate group from the 1′ to the 6′, or from the 6′ to the 1′ position in mannose phosphate. However, in the hyperthermophilic archaeon Thermococcus kodakarensis, a single gene, Tk1108, encodes a protein with both PGM and PMM activities. Here, we report biophysical analysis and the 2.45 Å resolution cryo-EM structure of this novel enzyme. Our results demonstrate a specific arrangement of the four subunits in the quaternary structure, displaying a distinct catalytic cleft required for the bifunctional activity at extremely high temperatures. To the best of our knowledge, this is the first biophysical characterization and cryo-EM structure elucidation of a thermostable, bifunctional PGM/PMM.

Sugars act as signaling molecules, whose signal transduction pathways may lead to the activation or inactivation of gene expression. Whole-genome transcript profiling reveals that the flavonoid and anthocyanin biosynthetic pathways are strongly up-regulated following sucrose (Suc) treatment. Besides mRNA accumulation, Suc affects both flavonoid and anthocyanin contents. We investigated the effects of sugars (Suc, glucose, and fructose) on genes coding for flavonoid and anthocyanin biosynthetic enzymes in Arabidopsis (Arabidopsis thaliana). The results indicate that the sugar-dependent up-regulation of the anthocyanin synthesis pathway is Suc specific. An altered induction of several anthocyanin biosynthetic genes, consistent with in vivo sugar modulation of mRNA accumulation, is observed in the phosphoglucomutase Arabidopsis mutant accumulating high levels of soluble sugars.

Growth is driven by newly fixed carbon in the light, but at night it depends on reserves, like starch, that are laid down in the light. Unless plants coordinate their growth with diurnal changes in the carbon supply, they will experience acute carbon starvation during the night. Protein synthesis represents a major component of cellular growth. Polysome loading was investigated during the diurnal cycle, an extended night, and low CO₂ in Arabidopsis (Arabidopsis ihaliana) Columbia (Col-0) and in the starchless phosphoglucomutase (pgm) mutant. In Col-0, polysome loading was 60% to 70% in the light, 40% to 45% for much of the night, and less than 20% in an extended night, while in pgm, it fell to less than 25% early in the night. Quantification of ribosomal RNA species using quantitative reverse transcription-polymerase chain reaction revealed that polysome loading remained high for much of the night in the cytosol, was strongly light dependent in the plastid, and was always high in mitochondria. The rosette sucrose content correlated with overall and with cytosolic polysome loading. Ribosome abundance did not show significant diurnal changes. However, compared with Col-0, pgm had decreased and increased abundance of plastidic and mitochondrial ribosomes, respectively. Incorporation of label from ¹³CO₂ into protein confirmed that protein synthesis continues at a diminished rate in the dark. Modeling revealed that a decrease in polysome loading at night is required to balance protein synthesis with the availability of carbon from starch breakdown. Costs are also reduced by using amino acids that accumulated in the previous light period. These results uncover a tight coordination of protein synthesis with the momentary supply of carbon.

Penetration resistance represents the first level of plant defense against phytopathogenic fungi. Here, we report that the starch-deficient Arabidopsis thaliana phosphoglucomutase (pgm) mutant has impaired penetration resistance against the hemibiotrophic fungus Colletotrichum higginsianum. We could not determine any changes in leaf cutin and epicuticular wax composition or indolic glucosinolate levels, but detected complex alterations in the cell wall monosaccharide composition of pgm. Notably, other mutants deficient in starch biosynthesis (adg1) or mobilization (sex1) had similarly affected cell wall composition and penetration resistance. Glycome profiling analysis showed that both overall cell wall polysaccharide extractability and relative extractability of specific pectin and xylan epitopes were affected in pgm, suggesting extensive structural changes in pgm cell walls. Screening of mutants with alterations in content or modification of specific cell wall monosaccharides indicated an important function of pectic polymers for penetration resistance and hyphal growth of C. higginsianum during the biotrophic interaction phase. While mutants with affected pectic rhamnogalacturonan-I (mur8) were hypersusceptible, penetration frequency and morphology of fungal hyphae were impaired on pmr5 pmr6 mutants with increased pectin levels. Our results reveal a strong impact of starch metabolism on cell wall composition and suggest a link between carbohydrate availability, cell wall pectin and penetration resistance.

The precise control of multiple heterologous enzyme expression levels in one Escherichia coli strain is important for cascade biocatalysis, metabolic engineering, synthetic biology, natural product synthesis, and studies of complexed proteins. We systematically investigated the co-expression of up to four thermophilic enzymes (i.e., α-glucan phosphorylase (αGP), phosphoglucomutase (PGM), glucose 6-phosphate dehydrogenase (G6PDH), and 6-phosphogluconate dehydrogenase (6PGDH)) in E. coli BL21(DE3) by adding T7 promoter or T7 terminator of each gene for multiple genes in tandem, changing gene alignment, and comparing one or two plasmid systems. It was found that the addition of T7 terminator after each gene was useful to decrease the influence of the upstream gene. The co-expression of the four enzymes in E. coli BL21(DE3) was demonstrated to generate two NADPH molecules from one glucose unit of maltodextrin, where NADPH was oxidized to convert xylose to xylitol. The best four-gene co-expression system was based on two plasmids (pET and pACYC) which harbored two genes. As a result, apparent enzymatic activities of the four enzymes were regulated to be at similar levels and the overall four-enzyme activity was the highest based on the formation of xylitol. This study provides useful information for the precise control of multi-enzyme-coordinated expression in E. coli BL21(DE3).