Affinity For Glucose Research Articles

Chemosensitive Properties of Electrochemically Synthesized Poly-3-Thienylboronic Acid: Conductometric Detection of Glucose and Other Diol-Containing Compounds under Electrical Affinity Control.

Due to the presence of the boronic acid moieties, poly-3-thienylboronic acid has an affinity for saccharides and other diol-containing compounds. Thin films of this novel chemosensitive polymer were synthesized electrochemically on the gold surface. The adhesion of the polymer was enhanced by the deposition of a monomolecular layer of thiophenol. The technology was used to fabricate conductometric sensors for glucose and other diol-containing compounds. Simultaneous two- and four-electrode conductivity measurements were performed. The chemical sensitivity to sorbitol, fructose, glucose, and ethylene glycol was studied at different pH and electrode potentials, and the corresponding binding constants were obtained. Depending on the electrode potential, the reciprocal values of the binding constants of glucose to poly-3-thienylboronic acid at neutral pH are in the range of 0.2 mM-1.0 mM. The affinity for glucose has been studied in buffer solutions and in solutions containing the major components of human blood. It was shown that the presence of human serum albumin increases the affinity of poly-3-thienylboronic acid for diol-containing compounds.

Phaseolus vulgaris STP13.1 is an H+-coupled monosaccharide transporter, present in source leaves and seed coats, with higher substrate affinity at depolarized potentials.

Sugar transport proteins (STPs) are high-affinity H+-coupled hexose symporters. Recently, the contribution of STP13 to bacterial and fungal pathogen resistance across multiple plant species has garnered significant interest. Quantitative PCR analysis of source leaves, developing embryos, and seed coats of Phaseolus vulgaris L. (common bean) revealed that PvSTP13.1 was expressed in source leaves and seed coats throughout seed development. In contrast, PvSTP13.1 transcripts were detected at exceedingly low levels in developing embryos. To characterize the transport mechanism, PvSTP13.1 was expressed in Xenopus laevis oocytes, and inward-directed currents were analyzed using two-electrode voltage clamping. PvSTP13.1 was shown to function as an H+-coupled monosaccharide symporter exhibiting a unique high affinity for hexoses and aldopentoses at depolarized membrane potentials. Specifically, of the 31 assessed substrates, which included aldohexoses, deoxyhexoses, fructose, 3-O-methyl-D-glucose, aldopentoses, polyols, glycosides, disaccharides, trisaccharides, and glucuronic acid, PvSTP13.1 displayed the highest affinity (K 0.5) for glucose (43 μM), mannose (92 μM), galactose (145 μM), fructose (224 μM), xylose (1.0mM), and fucose (3.7mM) at pH5.6 at a depolarized membrane potential of -40 mV. The results presented here suggest PvSTP13.1 contributes to retrieval of hexoses from the apoplasmic space in source leaves and coats of developing seeds.

Complete Glucose Electrooxidation Enabled by Coordinatively Unsaturated Copper Sites in Metal-Organic Frameworks.

The electrocatalytic oxidation of glucose plays a vital role in biomass conversion, renewable energy, and biosensors, but significant challenges remain to achieve high selectivity and high activity simultaneously. In this study, we present a novel approach for achieving complete glucose electrooxidation utilizing Cu-based metal-hydroxide-organic framework (Cu-MHOF) featuring coordinatively unsaturated Cu active sites. In contrast to traditional Cu(OH)2 catalysts, the Cu-MHOF exhibits a remarkable 40-fold increase in electrocatalytic activity for glucose oxidation, enabling exclusive oxidation of glucose into formate and carbonate as the final products. The critical role of open metal sites in enhancing the adsorption affinity of glucose and key intermediates was confirmed by control experiments and density functional theory simulations. Subsequently, a miniaturized nonenzymatic glucose sensor was developed showing superior performance with a high sensitivity of 214.7 μA mM-1 cm-2 , a wide detection range from 0.1 μM to 22 mM, and a low detection limit of 0.086 μM. Our work provides a novel molecule-level strategy for designing catalytically active sites and could inspire the development of novel metal-organic framework for next-generation electrochemical devices.

Complete Glucose Electrooxidation Enabled by Coordinatively Unsaturated Copper Sites in Metal–Organic Frameworks

AbstractThe electrocatalytic oxidation of glucose plays a vital role in biomass conversion, renewable energy, and biosensors, but significant challenges remain to achieve high selectivity and high activity simultaneously. In this study, we present a novel approach for achieving complete glucose electrooxidation utilizing Cu‐based metal‐hydroxide‐organic framework (Cu‐MHOF) featuring coordinatively unsaturated Cu active sites. In contrast to traditional Cu(OH)2 catalysts, the Cu‐MHOF exhibits a remarkable 40‐fold increase in electrocatalytic activity for glucose oxidation, enabling exclusive oxidation of glucose into formate and carbonate as the final products. The critical role of open metal sites in enhancing the adsorption affinity of glucose and key intermediates was confirmed by control experiments and density functional theory simulations. Subsequently, a miniaturized nonenzymatic glucose sensor was developed showing superior performance with a high sensitivity of 214.7 μA mM−1 cm−2, a wide detection range from 0.1 μM to 22 mM, and a low detection limit of 0.086 μM. Our work provides a novel molecule‐level strategy for designing catalytically active sites and could inspire the development of novel metal–organic framework for next‐generation electrochemical devices.

Differential expression of HIF1A and its downstream target VEGFA in the main subtypes of renal cell carcinoma and their impact on patient survival.

Renal cell carcinoma (RCC) represents around 3% of all cancers, with the most frequent histological types being clear-cell RCC (ccRCC), followed by papillary (pRCC) and chromophobe (chRCC). Hypoxia-inducible factors (HIFs), which promote the expression of various target genes, including vascular endothelial growth factor (VEGF) and the high- affinity glucose transporter 1, have an important role in the pathogenesis of RCC. This study investigated the immunohistochemical expression of HIF-1α and VEGF-A, showing significantly higher HIF-1α nuclear expression in pRCC compared to ccRCC, while there was no significant difference in VEGF-A protein expression between the analyzed histological RCC subtypes. The quantitative reverse transcription polymerase chain reaction for HIF1A showed no statistical difference between histological types. Data from publicly available RNA sequencing databases were analyzed and showed that, compared to healthy kidney tissue, VEGFA was significantly up-regulated in ccRCC and significantly down-regulated in pRCC. The comparison between histological subtypes of RCC revealed that VEGFA was significantly up-regulated in ccRCC compared to both pRCC and chRCC. There was no statistically significant difference in survival time between HIF1A high- and low-expression groups of patients. As for VEGFA expression, pRCC patients with low expression had a significantly higher survival rate compared to patients with high VEGFA expression.

GLUT1 Overexpression Enhances 19-28z CAR-T Cell Expansion and Metabolic Fitness

The tumor microenvironment presents many obstacles to effective CAR T cell therapy. One of these obstacles is glucose competition from tumor and myeloid cells to the detriment of CAR T cells. We hypothesize here that CAR T cells with elevated levels of glucose transporter are better fit under such conditions, which will result in improved therapeutic efficacy. We overexpressed either GLUT1 or GLUT3 in CD19-targeted CAR T cells engineered with a clinically validated CAR (19-28z). GLUT1 is ubiquitously expressed in tissues and GLUT3 has a higher affinity for glucose. Upon in vitro antigen stimulation, 1928z-GLUT1 and 1928z-GLUT3 showed greater enrichment of CAR+ T cells and underwent more cell divisions than control 1928z-LNGFR under glucose-limiting conditions. In repetitive antigen stimulation assays, 1928z-GLUT1 expanded significantly more than 1928z-LNGFR cells in 10 mM or 5 mM glucose medium. Surprisingly, 1928z-GLUT3 CAR T cells faired markedly less well than 1928z-LNGFR controls, associated with reduced viability of 1928z-GLUT3 CAR T cells after 2 or 3 exposures to antigen. In the NALM6 acute lymphoblastic leukemia model, low-dose CAR T cell treatment with 1928z-LNGFR and 1928z-GLUT3 did not curtail rapid tumor progression, while 1928z-GLUT1 CAR T cells significantly increased survival. More abundant CAR+ T cells were found in the bone marrow and spleen of 1928z-GLUT1-treated mice. Interestingly, we observed consistent increases in CD62L+CD45RA+ Tscm population in 1928z-GLUT1 cells, including both CD8 and CD4 T cells. We flow-sorted CAR T cells from treated mice and performed SMARTer RNA-seq. GLUT1, but not GLUT3, significantly upregulated TCF7 and genes encoding glycolytic enzymes and electron transport chain, indicating that GLUT1 overexpression enhances both glycolysis and oxidative phosphorylation. To further test GLUT1-CAR-T function in tumor lines with high levels of glucose transporter, we generated a renal cell carcinoma (RCC) patient-derived xenograft (PDX) with ectopic expression of human CD19. CAR-T cells were repetitively stimulated with the RCC PDX under titrated glucose concentrations. 1928z-GLUT1 significantly improved CAR T cell viability compared to 1928z-LNGFR in low glucose conditions. The expansion of GLUT1 CAR-T cells in 10 mM and 5 mM glucose also surpassed that of LNGFR CAR-T cells. In vivo, 1928z-GLUT1-treated mice showed significantly less tumor burden than 1928z-LNGFR-treated mice. Overall, we developed a novel strategy for enhancing the metabolic fitness of 1928z CAR-T cells by constitutively overexpressing GLUT1. GLUT1 but not GLUT3 enhances glycolysis and oxidative phosphorylation in CAR-T cells, which sustains T-cell expansion and increases therapeutic efficacy. This strategy is under investigation with other CAR formats.

Glucokinase Variant Proteins Are Resistant to Fasting-Induced Uridine Diphosphate Glucose-Dependent Degradation in Maturity-Onset Diabetes of the Young Type 2 Patients.

We previously reported that glucokinase undergoes ubiquitination and subsequent degradation, a process mediated by cereblon, particularly in the presence of uridine diphosphate glucose (UDP-glucose). In this context, we hereby present evidence showcasing the resilience of variant glucokinase proteins of maturity-onset diabetes of the young type 2 (MODY2) against degradation and, concomitantly, their influence on insulin secretion, both in cell lines and in the afflicted MODY2 patient. Hence, glucose-1-phodphate promotes UDP-glucose production by UDP-glucose pyrophosphorylase 2; consequently, UDP-glucose-dependent glucokinase degradation may occur during fasting. Next, we analyzed glucokinase variant proteins from MODY2 or persistent hyperinsulinemic hypoglycemia in infancy (PHHI). Among the eleven MODY2 glucokinase-mutated proteins tested, those with a lower glucose-binding affinity exhibited resistance to UDP-glucose-dependent degradation. Conversely, the glucokinaseA456V-mutated protein from PHHI had a higher glucose affinity and was sensitive to UDP-glucose-dependent degradation. Furthermore, in vitro studies involving UDP-glucose-dependent glucokinase variant proteins and insulin secretion during fasting in Japanese MODY2 patients revealed a strong correlation and a higher coefficient of determination. This suggests that UDP-glucose-dependent glucokinase degradation plays a significant role in the pathogenesis of glucose-homeostasis-related hereditary diseases, such as MODY2 and PHHI.

SAT163 Title: Adult-onset Hyperinsulinemic Hypoglycemia Due To An Activating Mutation In Glucokinase

Abstract Disclosure: S. Vaid: None. R. Ghosh: None. H. Elenius: None. C. Cochran: None. R. Chang: None. N. Nilubol: None. R. Muniyappa: None. Introduction: Glucokinase (GK), the key β-cell glucose sensor, determines the threshold for glucose-stimulated insulin secretion. Activating mutations of GK are infrequent causes (prevalence of 1.2%) of congenital hyperinsulinemic hypoglycemia (HH). Adult-onset of severe hypoglycemia due to GK-HH is extremely rare. Clinical Case: A 26-year-old well-nourished female (BMI, 27 kg/m2) with a recent history of dizziness, tremulousness, fatigue, sweating, and hunger, associated with weight gain presented for further workup. Hypoglycemia was noted, and Whipple's triad was confirmed. She had no family history of endocrine disease or hypoglycemia. Supervised fasting promptly produced symptomatic hypoglycemia with hyperinsulinemia. Laboratory studies revealed a low glucose level at 44 mg/dL; a plasma insulin level at 93 μIU/mL (<3 μIU/ml); a C-peptide level at 8.1 ng/mL (<0.6 ng/mL); pro-insulin at 266 pmol/L (<5 pmol/L); and beta-hydroxybutyrate <2.7 mmol/L. IGF2/IGF-1 ratio was 3.1 (<10) and renal and liver function was normal. Interestingly, a mixed meal also provoked significant hypoglycemia within an hour of consumption of a meal. Urine for sulfonylurea screen was negative, and so were anti-insulin antibodies. Imaging of the pancreas with computed tomography (CT), magnetic resonance imaging (MRI), and endoscopic ultrasound revealed a 1.2x0.8cm nodule on the superior margin of the body of the pancreas. 68Ga-DOTATATE​​ PET/CT (targeting somatostatin receptors) showed mild uptake coinciding with the nodule on the CT scan. Arteriography with calcium stimulation and venous sampling (ASVS) was non-localizing. The patient subsequently underwent laparoscopic exploration with intraoperative ultrasound (IOUS) of the pancreas followed by the enucleation of the pancreatic nodule. Histopathology of the nodule revealed a normal pancreatic tissue with no evidence of a neuroendocrine tumor. Change to multiple small meals, addition of cornstarch to diet, continuous blood glucose monitoring (CGM), diazoxide (70 mg oral, three times a day), and monthly octreotide LAR (30 mg) has allowed the patient to avoid hypoglycemia. Genetic testing by analysis of the genes known to cause hypoglycemia revealed a heterozygous GCK variant [c.1367C>T (p.Ala456Val), which was predicted to be a pathological mutation. This mutation is known to increase affinity for glucose, which leads to exaggerated insulin secretion. Conclusion: Our study highlights that in adults with non-insulinoma pancreatogenous hypoglycemia, genetic causes of HH should be considered in the differential diagnosis. Presentation: Saturday, June 17, 2023

Nanozymes based on octahedral platinum nanocrystals with {111} surface facets: glucose oxidase mimicking activity in electrochemical sensors

The ability of shape-controlled octahedral Pt nanoparticles to act as nanozyme mimicking glucose oxidase enzyme is reported. Extended {111} particle surface facets coupled with a size comparable to natural enzymes and easy-to-remove citrate coating give high affinity for glucose, comparable to the enzyme as proven by the steady-state kinetics of glucose electrooxidation. The easy and thorough removal of the citrate coating, demonstrated by X-ray photoelectron spectroscopy analysis, allows a highly stable deposition of the nanozymes on the electrode. The glucose electrochemical detection (at −0.2 V vs SCE) shows a linear response between 0.36 and 17 mM with a limit of detection of 110 μM. A good reproducibility has been achieved, with an average relative standard deviation (RSD) value of 9.1% (n = 3). Similarly, a low intra-sensor variability has been observed, with a RSD of 6.6% (n = 3). Moreover, the sensor shows a long-term stability with reproducible performances for at least 2 months (RSD: 7.8%). Tests in saliva samples show the applicability of Pt nanozymes to commercial systems for non-invasive monitoring of hyperglycemia in saliva, with recoveries ranging from 92 to 98%.Graphical

A Closed Loop Stimuli-Responsive Concanavalin A-Loaded Chitosan-Pluronic Hydrogel for Glucose-Responsive Delivery of Short-Acting Insulin Prototyped in RIN-5F Pancreatic Cells.

The optimal treatment of diabetes (in particular, type 1 diabetes-T1D) remains a challenge. Closed-loop systems (implants/inserts) provide significant advantages for glucose responsivity and providing real-time sustained release of rapid-acting insulin. Concanavalin A (ConA), a glucose affinity agent, has been used to design closed-loop insulin delivery systems but not without significant risk of leakage of ConA from the matrices and poor mechanical strength of the hydrogels impacting longevity and control of insulin release. Therefore, this work focused on employing a thermoresponsive co-forming matrix between Pluronic F-127 (PL) and structurally robust chitosan (CHT) via EDC/NHS coupling (i.e., covalent linkage of -NH2 from CHT and ConA to the -COOH of PL). The system was characterized for its chemical structure stability and integrity (FTIR, XRD and TGA), injectability, rheological parameters and hydrogel morphology (Texture Analysis, Elastosens TM Bio2 and SEM). The prepared hydrogels demonstrated shear-thinning for injectability with a maximum force of 4.9 ± 8.3 N in a 26G needle with sol-gel transitioning from 25 to 38 °C. The apparent yield stress value of the hydrogel was determined to be 67.47 Pa. The insulin loading efficiency within the hydrogel matrix was calculated to be 46.8%. Insulin release studies revealed glucose responsiveness in simulated glycemic media (4 and 10 mg/mL) over 7 days (97%) (305 nm via fluorescence spectrophotometry). The MTT studies were performed over 72 h on RIN-5F pancreatic cells with viability results >80%. Results revealed that the thermoresponsive hydrogel is a promising alternative to current closed-loop insulin delivery systems.

Kinetic, genomic, and physiological analysis reveals diversity in the ecological adaptation and metabolic potential of Brachybacterium equifaecis sp. nov. isolated from horse feces.

Brachybacterium species have been identified in various ecological niches and belong to the family Dermabacteriaceae within the phylum Actinobacteria. In this study, we isolated a novel Brachybacterium equifaecis JHP9 strain from horse feces and compared its kinetic, biochemical, and genomic features with those of other Brachybacterium strains. Moreover, comparative genomic analysis using publicly available Brachybacterium genomes was performed to determine the properties involved in their ecological adaptation and metabolic potential. Novel species delineation was determined phylogenetically through 16S rRNA gene similarity (up to 97.9%), average nucleotide identity (79.5-82.5%), average amino acid identity (66.7-75.8%), and in silico DNA-DNA hybridization (23.7-27.9) using closely related strains. This study also presents the first report of the kinetic properties of Brachybacterium species. Most of the Brachybacterium strains displayed high oxygen (K m(app) =1.6-24.2 µM) and glucose (K m(app) =0.73-1.22 µM) affinities, which may manifest niche adaptations. Various carbohydrate metabolisms under aerobic and anaerobic conditions, antibiotic resistance, mobile genetic elements, carbohydrate-active enzymes, lactic acid production, and the clustered regularly interspaced short palindromic repeats-Cas and bacteriophage exclusion systems were observed in the genotypic and/or phenotypic properties of Brachybacterium species, suggesting their genome flexibility, defense mechanisms, and adaptability. Our study contributes to the knowledge of the kinetic, physiological, and genomic properties of Brachybacterium species, including the novel JHP9 strain, which advocates for their tolerant and thriving nature in various environments, leading to their ecological adaptation. IMPORTANCE Basic physiological and genomic properties of most of the Brachybacterium isolates have been studied; however, the ability of this bacterium to adapt to diverse environments, which may demonstrate its role in niche differentiation, is to be identified yet. Therefore, here, we explored cellular kinetics, metabolic diversity, and ecological adaptation/defensive properties of the novel Brachybacterium strain through physiological and comparative genomic analysis. In addition, we presented the first report examining Brachybacterium kinetics, indicating that all strains of Brachybacterium, including the novel one, have high oxygen and glucose affinity. Furthermore, the comparative genomic analysis also revealed that the novel bacterium contains versatile genomic properties, which provide the novel bacterium with significant competitive advantages. Thus, in-depth genotypic and phenotypic analysis with kinetic properties at the species level of this genus is beneficial in clarifying its differential characteristics, conferring the ability to inhabit diverse ecological niches.

Genomic insights into metabolic flux in hummingbirds.

Hummingbirds are very well adapted to sustain efficient and rapid metabolic shifts. They oxidize ingested nectar to directly fuel flight when foraging but have to switch to oxidizing stored lipids derived from ingested sugars during the night or long-distance migratory flights. Understanding how this organism moderates energy turnover is hampered by a lack of information regarding how relevant enzymes differ in sequence, expression, and regulation. To explore these questions, we generated a chromosome-scale genome assembly of the ruby-throated hummingbird (A. colubris) using a combination of long- and short-read sequencing, scaffolding it using existing assemblies. We then used hybrid long- and short-read RNA sequencing of liver and muscle tissue in fasted and fed metabolic states for a comprehensive transcriptome assembly and annotation. Our genomic and transcriptomic data found positive selection of key metabolic genes in nectivorous avian species and deletion of critical genes (SLC2A4, GCK) involved in glucostasis in other vertebrates. We found expression of a fructose-specific version of SLC2A5 putatively in place of insulin-sensitive SLC2A5, with predicted protein models suggesting affinity for both fructose and glucose. Alternative isoforms may even act to sequester fructose to preclude limitations from transport in metabolism. Finally, we identified differentially expressed genes from fasted and fed hummingbirds, suggesting key pathways for the rapid metabolic switch hummingbirds undergo.

Reversible Recognition-Based Boronic Acid Probes for Glucose Detection in Live Cells and Zebrafish.

Glucose, a critical source of energy, directly determines the homeostasis of the human body. However, due to the lack of robust imaging probes, the mechanism underlying the changes of glucose homeostasis in the human body remains unclear. Herein, diboronic acid probes with good biocompatibility and high sensitivity were synthesized based on an ortho-aminomethylphenylboronic acid probe, phenyl(di)boronic acid (PDBA). Significantly, by introducing the water-solubilizing group -CN directly opposite the boronic acid group and -COOCH3 or -COOH groups to the β site of the anthracene in PDBA, we obtained the water-soluble probe Mc-CDBA with sensitive response (F/F0 = 47.8, detection limit (LOD) = 1.37 μM) and Ca-CDBA with the highest affinity for glucose (Ka = 4.5 × 103 M-1). On this basis, Mc-CDBA was used to identify glucose heterogeneity between normal and tumor cells. Finally, Mc-CDBA and Ca-CDBA were used for imaging glucose in zebrafish. Our research provides a new strategy for designing efficient boronic acid glucose probes and powerful new tools for the evaluation of glucose-related diseases.

Iron effects localization of Ght5 in fission yeast.

Iron is an essential cofactor for eukaryotic cells, as well as a toxic metal under certain conditions. On the other hand, glucose is the preferred energy and carbon source by most organisms and is an important signaling molecule in the regulation of biological processes. In Schizosaccharomyces pombe, the Ght5 hexose transporter, known as a high affinity glucose transporter, is required for cell proliferation in the low glucose condition. In this study, it is aimed to investigate the effects of iron stress on the Ght5 hexose transporter under glucose repression and derepression conditions. The effect of iron stress on the expression profile of the ght5 gene was analyzed by RT-qPCR and western blot. The localization of the Ght5-mNeongreen fusion protein examined with confocal microscopy. As a result, it was revealed that iron stress had an inhibitory effect on ght5 expression, and it altered Ght5 localization on the cell surface causing accumulation in the cytoplasm.

Using the AKAR3-EV biosensor to assess Sch9p- and PKA-signalling in budding yeast.

Budding yeast uses the TORC1-Sch9p and cAMP-PKA signalling pathways to regulate adaptations to changing nutrient environments. Dynamic and single-cell measurements of the activity of these cascades will improve our understanding of the cellular adaptation of yeast. Here, we employed the AKAR3-EV biosensor developed for mammalian cells to measure the cellular phosphorylation status determined by Sch9p and PKA activity in budding yeast. Using various mutant strains and inhibitors, we show that AKAR3-EV measures the Sch9p- and PKA-dependent phosphorylation status in intact yeast cells. At the single-cell level, we found that the phosphorylation responses are homogenous for glucose, sucrose, and fructose, but heterogeneous for mannose. Cells that start to grow after a transition to mannose correspond to higher normalized Förster resonance energy transfer (FRET) levels, in line with the involvement of Sch9p and PKA pathways to stimulate growth-related processes. The Sch9p and PKA pathways have a relatively high affinity for glucose (K0.5 of 0.24 mM) under glucose-derepressed conditions. Lastly, steady-state FRET levels of AKAR3-EV seem to be independent of growth rates, suggesting that Sch9p- and PKA-dependent phosphorylation activities are transient responses to nutrient transitions. We believe that the AKAR3-EV sensor is an excellent addition to the biosensor arsenal for illuminating cellular adaptation in single yeast cells.

Efficient conversion of glucose to 5-hydroxymethylfurfural by multi-functionalized γ-Al2O3 beads

Multi-functionalized γ-Al2O3 beads with glucose affinity, suitable hydrophobicity and the synergistic effect of Lewis acid and Brønsted acid were constructed.

A clinical mutation in glucokinase causing maturity-onset diabetes in the young type 2 increases enzyme activity.

Glucokinase (GCK) is the pancreatic β-cell glucose sensor, and its kinetics are key to that purpose. A slow transition step, displayed as non-hyperbolic kinetics, and a low affinity for glucose characterize GCK. Mutations in GCK associated with maturity-onset diabetes of the young type 2 (MODY2) previously describedreduce the functionality of the human pancreatic β-cell, leading to diabetic clinical phenotypes. We present a kinetic characterization of the G448D mutation identified in a MODY2 patient, which is one of the first mutations to exhibit increased functionality. This mutant displays increased activity, high affinity for both Mg2+ -ATP and glucose, hyperbolic kinetics and increased phosphorylation potential. Hyperbolic kinetics and assays in the presence of glycerol indicate that G448D lacks the slow transition step crucial for the pancreatic β-cell glucose sensor function.

High-Linearity Hydrogel-Based Capacitive Sensor Based on Con A-Sugar Affinity and Low-Melting-Point Metal.

Continuous glucose monitoring (CGM) plays an important role in the treatment of diabetes. Affinity sensing based on the principle of reversible binding to glucose does not produce intermediates, and the specificity of concanavalin A (Con A) to glucose molecules helps to improve the anti-interference performance and long-term stability of CGM sensors. However, these affinity glucose sensors have some limitations in their linearity with a large detection range, and stable attachment of hydrogels to sensor electrodes is also challenging. In this study, a capacitive glucose sensor with high linearity and a wide detection range was proposed based on a glucose-responsive DexG–Con A hydrogel and a serpentine coplanar electrode made from a low-melting-point metal. The results show that within the glucose concentration range of 0–20 mM, the sensor can achieve high linearity (R2 = 0.94), with a sensitivity of 33.3 pF mM−1, and even with the larger glucose concentration range of 0–30 mM the sensor can achieve good linearity (R2 = 0.84). The sensor also shows resistance to disturbances of small molecules, good reversibility, and long-term stability. Due to its low cost, wide detection range, high linearity, good sensitivity, and biocompatibility, the sensor is expected to be used in the field of continuous monitoring of blood glucose.

MicroRNAs-mediated regulation of glucose transporter (GLUT) expression in glioblastoma.

Current knowledge about the role of microRNAs (miRNAs) in tumor glucose metabolism is growing, and a number of studies regularly confirm the impact miRNAs can have on glucose metabolism reprogramming in tumors. However, there remains a lack of understanding of the broader perspective on the role of miRNAs in energy reprogramming in glioblastoma. An important role in the metabolism of glucose is played by carrier proteins that ensure its transmembrane movement. Carrier proteins in mammalian cells are glucose transporters (GLUTs). In total, 12 types of GLUTs are distinguished, differing in localization, affinity for glucose and ability to regulate. The fact of increased consumption of glucose in tumors compared to non-proliferating normal tissues is known. Tumor cells need glucose to ensure their survival and growth, so the type of transport proteins like GLUT are critical for them. Previous studies have shown that GLUT-1 and GLUT-3 may play an important role in the development of some types of malignant tumors, including glioblastoma. In addition, there is evidence of how GLUT-1 and GLUT-3 expression is regulated by miRNAs in glioblastoma. Thus, the aim of this study is to highlight the role of specific miRNAs in modulating GLUT levels in order to take into account the use of miRNAs expression modulators as a useful strategy to increase the sensitivity of glioblastoma to current therapies.

Comprehensive identification of sugar transporters in the Malus spp. genomes reveals their potential functions in sugar accumulation in apple fruits

• 130 sugar transporter genes were identified in the updated apple genome GDDH13 v1.1. • 57 ST genes were expressed in the cultivar Greensleeves, and 59 in the cultivar Fuji. • MdHT14.1 could transport glucose and fructose, while MdSUT2.1/2.2 and MdSWEET15.2 could transport sucrose. • Overexpression MdVGT1 or MdpGlcT2.1 in apple fruits significantly increased glucose, while overexpression of MdSUT2.1 increased sucrose or of MdSOT1 increased sorbitol. The transport of sugar across membranes is essential for maintaining cellular sugar homeostasis and metabolic balance in plant cells, but there is limited information about the sugar transporter family in economically important fleshy fruits. Here, 130 sugar transporter genes were identified in the updated apple genome (GDDH13 v1.1). The sugar transporter (ST) genes clustered into ten subfamilies. The apple ST genes mapped to all 17 apple chromosomes and had experienced whole-genome duplication (WGD)/segmental duplication and tandem duplication during the process of apple domestication. Expression profiles of the STs were analyzed in different tissues and during the stages of fruit development. In Malus × domestica , 57 ST genes were expressed in the cultivar ‘Greensleeves’, and 59 in ‘Fuji’. Different ST genes were highly expressed in mature leaves, shoot tips, young fruits, and mature fruits, indicating their divergent functions in different tissues. Heterologous expression experiments in yeast strains lacking STs indicated that MdHT14.1 is the sugar transporter with the highest affinity for glucose and fructose, while MdSUT2.1/2.2 and MdSWEET15.2 had the highest affinity for sucrose. Transient overexpression in apple fruits of MdVGT1 and MdpGlcT2.1 significantly increased glucose concentration, while overexpression of MdSUT2.1 increased sucrose level or of MdSOT1 increased sorbitol concentration. This study demonstrated the expansion and functional divergence of the sugar transporter gene family in domesticated apple and will enable further investigation of the molecular mechanisms of sugar transport and metabolism in apple and other important fleshy fruit crops.