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Recently studied N-(β-d-glucopyranosyl)-3-aryl-1,2,4-triazole-5-carboxamides have proven to be low micromolar inhibitors of glycogen phosphorylase (GP), a validated target for the treatment of type 2 diabetes mellitus. Since in other settings, the bioisosteric replacement of the 1,2,4-triazole moiety with imidazole resulted in significantly more efficient GP inhibitors, in silico calculations using Glide molecular docking along with unbound state DFT calculations were performed on N-(β-d-glucopyranosyl)-arylimidazole-carboxamides, revealing their potential for strong GP inhibition. The syntheses of the target compounds involved the formation of an amide bond between per-O-acetylated β-d-glucopyranosylamine and the corresponding arylimidazole-carboxylic acids. Kinetics experiments on rabbit muscle GPb revealed low micromolar inhibitors, with the best inhibition constants (Kis) of ~3–4 µM obtained for 1- and 2-naphthyl-substituted N-(β-d-glucopyranosyl)-imidazolecarboxamides, 2b–c. The predicted protein–ligand interactions responsible for the observed potencies are discussed and will facilitate the structure-based design of other inhibitors targeting this important therapeutic target. Meanwhile, the importance of the careful consideration of ligand tautomeric states in binding calculations is highlighted, with the usefulness of DFT calculations in this regard proposed. [ABSTRACT FROM AUTHOR]

The study of the relationship between the activity and stability of enzymes under crowding conditions in the presence of osmolytes is important for understanding the functioning of a living cell. The effect of osmolytes (trehalose and betaine) on the secondary and tertiary structure and activity of muscle glycogen phosphorylase b (Ph b) under crowding conditions created by PEG 2000 and PEG 20000 was investigated using dynamic light scattering, differential scanning calorimetry, circular dichroism spectroscopy, fluorimetry and enzymatic activity assay. At 25 °C PEGs increased Ph b activity, but PEG 20000 to a greater extent. Wherein, PEG 20000 significantly destabilized its tertiary and secondary structure, in contrast to PEG 2000. Trehalose removed the effects of PEGs on Ph b , while betaine significantly reduced the activating effect of PEG 20000 without affecting the action of PEG 2000. Under heat stress at 48 °C, the protective effect of osmolytes under crowding conditions was more pronounced than at room temperature, and the Ph b activity in the presence of osmolytes was higher in these conditions than in diluted solutions. These results provide important insights into the complex mechanism, by which osmolytes affect the structure and activity of Ph b under crowding conditions. • PEG 2000 and especially PEG 20000 destabilized structure of Ph b and increased its enzymatic activity. • Trehalose completely removed destabilizing effects of both PEGs but betaine only partialy • When heated in the presence of osmolytes, Ph b activity under crowding conditions was higher than in dilute solutions. • Protective effect of osmolytes under crowding conditions was most noticeable under heat stress. [ABSTRACT FROM AUTHOR]

Drought stress is a common abiotic stress, and Lupinus polyphyllus presents strong adaptability, but its drought resistance mechanism has not been explored. This study used PEG-6000 to simulate drought stress, and the H2O2 content, O2− generation rate and MDA content were determined. Transcriptome sequencing and untargeted metabolome analyses were also carried out on an Iceland germplasm and American B germplasm under different drought stress durations. The results showed that the gene regulation range in the American B germplasm was greater, whether genes were upregulated or downregulated. And the number of genes in the American B germplasm was higher than that in the Iceland germplasm. Additionally, the Iceland germplasm produced less peroxide under PEG stress than the Iceland germplasm. The Iceland germplasm was more stable than the American B germplasm under PEG stress, which can be shown in two aspects: peroxide content and gene regulation quantity. Joint transcriptomics and metabolomics analysis showed that genes and metabolites related to secondary and carbon metabolism were mainly involved in the response of Lupinus polyphyllus to PEG-simulated drought stress. The metabolites mainly included phenylalanine, tyrosine, trans-2-hydroxycinnamate, starch synthase, 1,4-alpha glucan branching enzyme and glycogen phosphorylase, and genes mainly included COMT, F5H, REF1, CAD, UGT72E and TPS. These results provided genetic resources and a theoretical basis for further molecular breeding of Lupinus polyphyllus. [ABSTRACT FROM AUTHOR]

Glucagon rapidly and profoundly stimulates hepatic glucose production (HGP), but for reasons that are unclear, this effect normally wanes after a few hours, despite sustained plasma glucagon levels. This study characterized the time course of glucagonmediated molecular events and their relevance to metabolic flux in the livers of conscious dogs. Glucagon was either infused into the hepato-portal vein at a sixfold basal rate in the presence of somatostatin and basal insulin, or it was maintained at a basal level in control studies. In one control group, glucose remained at basal, whereas in the other, glucose was infused to match the hyperglycemia that occurred in the hyperglucagonemic group. Elevated glucagon caused a rapid (30 min) and largely sustained increase in hepatic cAMP over 4 h, a continued elevation in glucose-6-phosphate (G6P), and activation and deactivation of glycogen phosphorylase and synthase activities, respectively. Net hepatic glycogenolysis increased rapidly, peaking at 15 min due to activation of the cAMP/PKA pathway, then slowly returned to baseline over the next 3 h in line with allosteric inhibition by glucose and G6P. Glucagon's stimulatory effect on HGP was sustained relative to the hyperglycemic control group due to continued PKA activation. Hepatic gluconeogenic flux did not increase due to the lack of glucagon's effect on substrate supply to the liver. Global gene expression profiling highlighted glucagon-regulated activation of genes involved in cellular respiration, metabolic processes, and signaling, as well as downregulation of genes involved in extracellular matrix assembly and development. [ABSTRACT FROM AUTHOR]

This study investigated the antidiabetic effect of vanillin using in vitro, in silico, and in vivo experimental models. Type 2 diabetes (T2D) was induced in male Sprague-Dawley (SD) rats using fructose–streptozotocin (STZ), then orally administered low (150 mg/kg bodyweight) or high (300 mg/kg bodyweight) dose of vanillin for 5 weeks intervention period. Vanillin suppressed the levels of blood glucose, serum cholesterol, triglyceride, low-density lipoprotein cholesterol (LDL-c), alanine transaminase (ALT), aspartate transaminase (AST), creatinine, urea, uric acid, when elevated serum insulin, HDL-cholesterol, and concomitantly improved pancreatic β-cell function, glucose tolerance, and pancreatic morphology. It also elevated both serum and pancreatic tissue GSH level, SOD and catalase activities, and hepatic glycogen level, while depleting malondialdehyde level, α-amylase, lipase, acetylcholinesterase, ATPase, ENTPDase and 5′-nucleotidase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, and glycogen phosphorylase activities. The results indicate the potent antidiabetic effect of vanillin against T2D and its associated complications. [ABSTRACT FROM AUTHOR]

BACKGROUND: Some environmental enrichment methods, such as occupational enrichment (OE), can improve fish growth, but little is known about its effects on fillet quality. In this study, we evaluated the effects of OE using underwater currents on different aspects of fillet quality and muscle metabolism in rainbow trout (Oncorhynchus mykiss), before and after a handling procedure (fasting). The trout were placed in groups of 30 in separate tanks in three treatments for 30 days: no artificial currents (CON), randomly fired underwater currents (RFC), and continuous underwater currents (CUC). Additionally, half of the individuals in each treatment were fasted (5 days, 45.2 °C days). RESULTS: Slaughter weight, condition factor, and relative growth were lower in CON fish, indicating a positive effect of OE on growth. Rigor mortis, muscle pH, and muscle glycogen levels were similar among treatments, indicating no effect of OE on classical measures of fillet quality. However, significant differences were found regarding fillet colour and muscle enzymes. The fillets of RFC fish were more salmon‐pink in colour, which is favoured by consumers. Also, activity levels of pyruvate kinase and glycogen phosphorylase in muscle were significantly higher in CUC fish, probably due to increased energy demands, as pumps were on continually in that treatment. CONCLUSION: Overall, RFC fish seemed to have received enough stimulation to improve growth while not being excessive in terms of exhausting the animals (avoiding negative effects on muscle metabolism), whereas OE may have provided a hormetic effect, allowing fish to better adjust to fasting. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Glycogen metabolism is a form of crucial metabolic reprogramming in cells. PYGB, the brain-type glycogen phosphorylase (GP), serves as the rate-limiting enzyme of glycogen catabolism. Evidence is mounting for the association of PYGB with diverse human diseases. This review covers the advancements in PYGB research across a range of diseases, including cancer, cardiovascular diseases, metabolic diseases, nervous system diseases, and other diseases, providing a succinct overview of how PYGB functions as a critical factor in both physiological and pathological processes. We present the latest progress in PYGB in the diagnosis and treatment of various diseases and discuss the current limitations and future prospects of this novel and promising target. [ABSTRACT FROM AUTHOR]

Some acute exercise effects are influenced by postexercise (PEX) diet, and these diet-effects are attributed to differential glycogen resynthesis. However, this idea is challenging to test rigorously. Therefore, we devised a novel genetic model to modify muscle glycogen synthase 1 (GS1) expression in rat skeletal muscle with an adeno-associated virus (AAV) short hairpin RNA knockdown vector targeting GS1 (shRNA-GS1). Contralateral muscles were injected with scrambled shRNA (shRNA-Scr). Muscles from exercised (2-hour-swim) and time-matched sedentary (Sed) rats were collected immediately postexercise (IPEX), 5-hours-PEX (5hPEX), or 9-hours-PEX (9hPEX). Rats in 5hPEX and 9hPEX experiments were refed (RF) or not-refed (NRF) chow. Muscles were analyzed for glycogen, abundance of metabolic proteins (pyruvate dehydrogenase kinase 4, PDK4; peroxisome proliferator-activated receptor γ coactivator-1α, PGC1α; hexokinase II, HKII; glucose transporter 4, GLUT4), AMP-activated protein kinase phosphorylation (pAMPK), and glycogen metabolism-related enzymes (glycogen phosphorylase, PYGM; glycogen debranching enzyme, AGL; glycogen branching enzyme, GBE1). shRNA-GS1 versus paired shRNA-Scr muscles had markedly lower GS1 abundance. IPEX versus Sed rats had lower glycogen and greater pAMPK, and neither of these IPEX-values differed for shRNA-GS1 versus paired shRNA-Scr muscles. IPEX versus Sed groups did not differ for abundance of metabolic proteins, regardless of GS1 knockdown. Glycogen in RF-rats was lower for shRNA-GS1 versus paired shRNA-Scr muscles at both 5hPEX and 9hPEX. HKII protein abundance was greater for 5hPEX versus Sed groups, regardless of GS1 knockdown or diet, and despite differing glycogen levels. At 9hPEX, shRNA-GS1 versus paired shRNA-Scr muscles had greater PDK4 and PGC1α abundance within each diet group. However, the magnitude of PDK4 or PGC1α changes was similar in each diet group regardless of GS1 knockdown although glycogen differed between paired muscles only in RF-rats. In summary, we established a novel genetic approach to investigate the relationship between muscle glycogen and other exercise effects. Our results suggest that exercise-effects on abundance of several metabolic proteins did not uniformly correspond to differences in postexercise glycogen. [ABSTRACT FROM AUTHOR]

The androgen receptor (AR) plays an important role in male-dominant hepatocellular carcinoma, and specific acquired somatic mutations of AR have been observed in HCC patients. Our previous research have established the role of AR wild type as one of the key oncogenes in hepatocarcinogenesis. However, the role of hepatic acquired somatic mutations of AR remains unknown. In this study, we identify two crucial acquired somatic mutations, Q62L and E81Q, situated close to the N-terminal activation function domain-1 of AR. These mutations lead to constitutive activation of AR, both independently and synergistically with androgens, making them potent driver oncogene mutations. Mechanistically, these N-terminal AR somatic mutations enhance de novo lipogenesis by activating sterol regulatory element-binding protein-1 and promote glycogen accumulation through glycogen phosphorylase, brain form, thereby disrupting the AMPK pathway and contributing to tumorigenesis. Moreover, the AR mutations show sensitivity to the AMPK activator A769662. Overall, this study establishes the role of these N- terminal hepatic mutations of AR as highly malignant oncogenic drivers in hepatocarcinogenesis and highlights their potential as therapeutic targets for patients harboring these somatic mutations. Several mutations proximal to the activation function domain-1 in androgen receptor lead to its constitutive activation and drive the development of hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

Glycogen phosphorylase (GP) is biologically active as a dimer of identical subunits, each activated by phosphorylation of the serine-14 residue. GP exists in three interconvertible forms, namely GPa (di-phosphorylated form), GPab (mono-phosphorylated form), and GPb (non-phosphorylated form); however, information on GPab remains scarce. Given the prevailing view that the two GP subunits collaboratively determine their catalytic characteristics, it is essential to conduct GPab characterization to gain a comprehensive understanding of glycogenolysis regulation. Thus, in the present study, we prepared rabbit muscle GPab from GPb, using phosphorylase kinase as the catalyst, and identified it using a nonradioactive phosphate-affinity gel electrophoresis method. Compared with the half-half GPa/GPb mixture, the as-prepared GPab showed a unique AMP-binding affinity. To further investigate the intersubunit communication in GP, its catalytic site was probed using pyridylaminated-maltohexaose (a maltooligosaccharide-based substrate comprising the essential dextrin structure for GP; abbreviated as PA-0) and a series of specifically modified PA-0 derivatives (substrate analogs lacking part of the essential dextrin structure). By comparing the initial reaction rates toward the PA-0 derivative (Vderivative) and PA-0 (VPA-0), we demonstrated that the Vderivative/VPA-0 ratio for GPab was significantly different from that for the half-half GPa/GPb mixture. This result indicates that the interaction between the two GP subunits significantly influences substrate recognition at the catalytic sites, thereby providing GPab its unique substrate recognition profile. [ABSTRACT FROM AUTHOR]

Ionic liquid-catalysed oxygenation of quinoxalin-2(1H)-one utilizing aerobic oxygen as a green oxidant under visible light conditions at room temperature has been described. Various N-1-alkyl and aryl-substituted quinoxalin-2(1H)-ones provided good yields of the desired products. The ionic-liquid tetramethylammonium hydroxide (TMAH) employed is readily available and promotes the oxygenation under additive and base-free conditions. The present procedure illustrates the applicability at gram scale reactions and showcases the subsequent conversion of the target product into glycogen phosphorylase inhibitors. [ABSTRACT FROM AUTHOR]

Although the presence of glycogen in platelets was established in the 1960s, its importance to specific functions (i.e., activation, secretion, aggregation, and clot contraction) remains unclear. Patients with glycogen storage disease often present with increased bleeding and glycogen phosphorylase (GP) inhibitors, when used as treatments for diabetes, induce bleeding in preclinical studies suggesting some role for this form of glucose in hemostasis. In the present work, we examined how glycogen mobilization affects platelet function using GP inhibitors (CP316819 and CP91149) and a battery of ex vivo assays. Blocking GP activity increased glycogen levels in resting and thrombin-activated platelets and inhibited platelet secretion and clot contraction, with minimal effects on aggregation. Seahorse energy flux analysis and metabolite supplementation experiments suggested that glycogen is an important metabolic fuel whose role is affected by platelet activation and the availability of external glucose and other metabolic fuels. Our data shed light on the bleeding diathesis in glycogen storage disease patients and offer insights into the potential effects of hyperglycemia on platelets. [ABSTRACT FROM AUTHOR]

Diabetes contributes to the rising global death rate. Despite scientific advancements in understanding and managing diabetes, no single therapeutic agent has been identified to effectively treat and prevent its progression. Consequently, the exploration for new antidiabetic therapeutics continues. This study aimed to investigate the antidiabetic bioactive ethyl acetate fraction of F. lutea at the molecular level to understand the molecular interactions and ligand-protein binding. To do this, the fraction underwent column chromatography fractionation to yield five compounds: lupeol, stigmasterol, α-amyrin acetate, epicatechin, and epiafzelechin. These compounds were evaluated in vitro through α-glucosidase inhibition and glucose utilization assays in C2C12 muscle and H-4-11-E liver cells using standard methods. In silico analysis was conducted using molecular docking and ADMET studies. Epicatechin exhibited the most potent α-glucosidase inhibition (IC50 = 5.72 ± 2.7 µg/mL), while epiafzelechin stimulated superior glucose utilization in C2C12 muscle cells (33.35 ± 1.8%) and H-4-11-E liver cells (46.7 ± 1.2%) at a concentration of 250 µg/mL. The binding energies of the isolated compounds for glycogen phosphorylase (1NOI) and α-amylase (1OSE) were stronger (<−8.1) than those of the positive controls. Overall, all tested compounds exhibited characteristics indicative of their potential as antidiabetic agents; however, toxicity profiling predicted epiafzelechin and epicatechin as better alternatives. The ethyl acetate fraction and its compounds, particularly epiafzelechin, showed promise as antidiabetic agents. However, further comprehensive studies are necessary to validate these findings. [ABSTRACT FROM AUTHOR]

Akebia trifoliata fruit is prone to crack after ripening, but little is known about the mechanism underlying the cracking process. This study integrated transcriptomic and metabolomic data, revealing significant changes in 398 metabolites and 8414 genes during ripening and cracking, mainly impacting cell-wall metabolism. Multi-omics joint analysis indicated that genes related to polygalacturonase, pectate lyase, α-amylase, and glycogen phosphorylase were up-regulated after cracking, degrading cell wall and starch. Concurrently, diminished photosynthetic metabolism and heightened phenylpropanoid metabolism suggested alterations in cuticle structure, potentially impacting cell-wall robustness. Numerous auxin and abscisic acid signaling-related genes were expressed, and we assume that they contributed to the promoting peel growth. These alterations collectively might compromise peel strength and elevate expanding pressure, potentially leading to A. trifoliata cracking. Transcription factors, predominantly ethylene response factors and helix-loop-helix family members, appeared to regulate these metabolic shifts. These findings provide valuable insights into A. trifoliata cracking mechanisms; however, direct experimental validation of these assumptions is necessary to strengthen these conclusions and expedite their commercial utilization. [ABSTRACT FROM AUTHOR]

Xu and colleagues recently revealed the critical role of Cryptosporidium 's feeder organelle in nutrient uptake, showcasing the parasite's ability to harness glucose and glucose-6-phosphate from host cells. This illuminates the sophisticated energy metabolism and survival strategies of the parasite, highlighting potential therapeutic targets. [ABSTRACT FROM AUTHOR]

Inhibition of glycogen breakdown blocks memory formation in young animals, but it stimulates the maintenance of the long‐term potentiation, a cellular mechanism of memory formation, in hippocampal slices of old animals. Here, we report that a 2‐week treatment with glycogen phosphorylase inhibitor BAY U6751 alleviated memory deficits and stimulated neuroplasticity in old mice. Using the 2‐Novel Object Recognition and Novel Object Location tests, we discovered that the prolonged intraperitoneal administration of BAY U6751 improved memory formation in old mice. This was accompanied by changes in morphology of dendritic spines in hippocampal neurons, and by "rejuvenation" of hippocampal proteome. In contrast, in young animals, inhibition of glycogen degradation impaired memory formation; however, as in old mice, it did not alter significantly the morphology and density of cortical dendritic spines. Our findings provide evidence that prolonged inhibition of glycogen phosphorolysis improves memory formation of old animals. This could lead to the development of new strategies for treatment of age‐related memory deficits. [ABSTRACT FROM AUTHOR]

Cyperus conglomeratus has been utilized in traditional medicine as an emollient, diuretic, analgesic, anthelmintic, and for other diseases. Furthermore, several biological activities have been reported for the plant extract and the isolated metabolites. The chromatographic investigation of an ethyl acetate extract of the aerial parts led to the isolation of three aurone derivatives (1–3) from the plant for the first time. Their structures were identified as aureusidin (1), aureusidin-4-methyl ether (2), and 5-methyl aureusidin (3) using 1D and 2D NMR techniques, along with mass spectrometry. The compounds were tested for their inhibitory activities against enzymes vital in metabolic diseases, especially diabetes, such as α-amylase, α-glucosidase, and glycogen phosphorylase. The results were expressed as percentage inhibition. The inhibitory activity of aurones against the tested enzymes was also analyzed by computational docking studies to provide a rational explanation for the observed results. The tested compounds formed stable interactions in terms of hydrogen bonding and hydrophobic interaction with the active site residues of the tested enzymes, and the results are in agreement with those of the in vitro antidiabetic activity. The compounds were also evaluated for their ability to support the growth and viability of beneficial bacteria in terms of prebiotic activities using two species, Lacticaseibacillus paracasei and Lacticaseibacillus rhamnosus, through the determination of prebiotic activity scores (Pscore). The findings of this study showed that C. conglomeratus is a potential natural source of bioactive agents. There is, however, a need for in vivo testing to evaluate this plant's efficacy for developing new drug entities in the future. [ABSTRACT FROM AUTHOR]

The present study was conducted to investigate the effects of high dietary carbohydrate levels on growth performance, enzyme activities, and gene expressions related to liver glucose metabolism and the intestinal microbiota of Lateolabrax maculatus juveniles. Two experimental diets with levels of carbohydrates (20% and 30%, named the NCD group and the HCD group, respectively) were designed to feed L. maculatus (initial weight 9.45 ± 0.03 g) for 56 days. The results showed that, compared with the NCD group, the condition factor (CF) was significantly elevated in the HCD group (p < 0.05). The plasma advanced glycosylation end products (AGEs), glycated serum protein (GSP), total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and glutamate aminotransferase (AST) were significantly higher in the HCD group than those in the NCD group (p < 0.05). The intestinal lipase, chymotrypsin, and α-amylase in the HCD group were significantly higher than those in the NCD group (p < 0.05). The liver superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and catalase (CAT) were significantly lower in the HCD group than in the NCD group (p < 0.05). The liver malondialdehyde (MDA) and hexokinase (HK) levels were significantly higher than those in the NCD group (p < 0.05). In the histopathological findings, liver cells in the HCD group appeared to have many vacuoles, and the number of lipid droplets increased. Compared with the NCD group, the relative expression of liver glucokinase (GK) and glycogen synthetase kinase-3 (GSK3β) genes in the HCD group was significantly increased (p < 0.05), while the relative expression of phosphoenolpyruvate carboxykinase (PEPCK) and glycogen phosphorylase (GP) genes in the HCD group was significantly reduced (p < 0.05). High-throughput 16S rRNA gene sequencing showed that high dietary carbohydrate intake changed the composition and structure of the intestinal microbiota. At the phylum level of the intestinal microbiota, high dietary carbohydrates decreased the relative abundance of Firmicutes and increased the relative abundance of Proteobacteria and Bacteroidetes. At the genus level of the intestinal microbiota, high carbohydrates decreased the relative abundance of Bacillus and increased the relative abundance of Photobacterium and Paraclostridium. From the results of this experiment on L. maculatus, high carbohydrates led to increased condition factor and liver glycogen, lipid deposition, decreased antioxidant capacity of the liver, increased relative abundance of harmful intestinal microorganisms, and disrupted glucose metabolism. [ABSTRACT FROM AUTHOR]

Lactate is an important metabolic substrate for sustaining brain energy requirements when glucose supplies are limited. Recurring exposure to hypoglycemia (RH) raises lactate levels in the ventromedial hypothalamus (VMH), which contributes to counterregulatory failure. However, the source of this lactate remains unclear. The current study investigates whether astrocytic glycogen serves as the major source of lactate in the VMH of RH rats. By decreasing the expression of a key lactate transporter in VMH astrocytes of RH rats, we reduced extracellular lactate concentrations, suggesting excess lactate was locally produced from astrocytes. To determine whether astrocytic glycogen serves as the major source of lactate, we chronically delivered either artificial extracellular fluid or 1,4-dideoxy-1,4-imino-d-arabinitol to inhibit glycogen turnover in the VMH of RH animals. Inhibiting glycogen turnover in RH animals prevented the rise in VMH lactate and the development of counterregulatory failure. Lastly, we noted that RH led to an increase in glycogen shunt activity in response to hypoglycemia and elevated glycogen phosphorylase activity in the hours following a bout of hypoglycemia. Our data suggest that dysregulation of astrocytic glycogen metabolism following RH may be responsible, at least in part, for the rise in VMH lactate levels. Article Highlights: Astrocytic glycogen serves as the major source of elevated lactate levels in the ventromedial hypothalamus (VMH) of animals exposed to recurring episodes of hypoglycemia. Antecedent hypoglycemia alters VMH glycogen turnover. Antecedent exposure to hypoglycemia enhances glycogen shunt activity in the VMH during subsequent bouts of hypoglycemia. In the immediate hours following a bout of hypoglycemia, sustained elevations in glycogen phosphorylase activity in the VMH of recurrently hypoglycemic animals contribute to sustained elevations in local lactate levels. [ABSTRACT FROM AUTHOR]

The high conservation of the three subtypes of glycogen phosphorylase (GP) presents significant challenges for specific inhibitor studies targeting GP. Our prior screening revealed that compound 1 exhibited unequal inhibitory activity against the three GP subtypes, with a noticeable effect against brain GP (PYGB). The commercially available ingliforib demonstrated potent inhibitory activity specifically against liver GP (PYGL). To guide the further design and screening of high-specificity inhibitors, the possible reasons for the differential inhibitory activity of two compounds against different GP subtypes were analyzed, with ingliforib as a reference, through molecular docking and molecular dynamics simulations. Initially, the study predicted the binding modes of ligands with the three GP receptor subtypes using molecular docking. Subsequently, this was validated by molecular dynamics experiments, and possible amino acid residues that had important interactions were explored. The strong correlation between the calculated interaction free energies and experimental inhibitory activity implied the reasonable binding conformations of the compounds. These findings offer insight into the different inhibitory activity of compound 1 and ingliforib against all three GP subtypes and provide guidance for the design of specific target molecules that regulate subtype selectivity. [ABSTRACT FROM AUTHOR]

Entamoeba histolytica is a parasitic protozoan that causes diarrheal disease in approximately 100 million people worldwide every year. E. histolytica has two forms, the growing trophozoite and the infectious cyst. Trophozoites colonizing the large intestine form cysts that are released into the environment. The ingestion of the cysts in contaminated food and water continues the disease cycle. Here, we investigated the role of glycogen in trophozoite growth and encystation. Glycogen is thought to provide precursors for the synthesis of chitin, a major component of the protective cyst wall. We propose that glycogen also serves as an energy source during metabolic adaptation to different nutrient environments. We examined the role of glycogen in E. histolytica by analyzing the growth and encystation of RNAi strains with reduced expression of the single gene-encoding glycogen synthase (GYS) or two of three genes encoding glycogen phosphorylase (PYG). The GYS RNAi strain had a greatly reduced glycogen accumulation, and both the GYS and PYG RNAi strains exhibited reduced growth in the glucose-poor medium. Both RNAi strains also showed reduced cyst production. Our results suggest glycogen synthesis and degradation are vital to the growth and adaptation of E. histolytica to a low-glucose environment such as that encountered in the large intestine. [ABSTRACT FROM AUTHOR]

Temperature is an important factor that conditions the physiological responses of fish, generating a stressful condition when in non-ideal parameters. Thus, the objective was to evaluate metabolic aspects in the muscle of fish Astyanax lacustris submitted to thermal shock. The specimens were subjected to 2, 6, 12, 24, 48, and 96 h of exposure to 15 °C and 31 1 °C, with their respective controls 23 °C. At 15 °C there was a reduction in glycogenolysis in the initial periods indicated by changes in glycogen phosphorylase (GP), pyruvate and lactate. Subsequently, there was an increase in GP activity, pyruvate levels and hexokinase activity in the next time periods, suggesting an increase in energy demand. At 31 °C there was observed low need for the protein metabolism, indicated by reduction in the activity of aspartate aminotransferase and alanine aminotransferase. At 15 °C, initial periods show an increase in glutathione reductase activity and an increase in carbonylated protein levels, indicating induction of oxidative stress for muscle. At 31 °C, there was a punctual increase in reduced glutathione levels at 24 h. In addition, the integrated biomarker response index proved to be a good ally in the evaluation of a set of biomarkers, corroborating the results observed by the biomarkers individually. Thus, it is possible to conclude that the acute thermal shock affects the metabolism of A. lacustris muscle, which undergoes rearrangements to deal with temperature, where 15 °C is more stressful than 31 °C. [Display omitted] • Glycogenolysis occurs at the initial time (2 h) of thermal shock at 15 °C. • Protein damage at 15 °C suggests muscle oxidative stress in Astyanax lacustris. • Thermal shock affects muscle metabolism with 15 °C more stressful than 31 °C. • IBR index analyses corroborate the individual enzymatic changes of the metabolic pathways. [ABSTRACT FROM AUTHOR]

The importance of studying the structural stability of proteins is determined by the structure–function relationship. Protein stability is influenced by many factors among which are freeze–thaw and thermal stresses. The effect of trehalose, betaine, sorbitol and 2-hydroxypropyl-β-cyclodextrin (HPCD) on the stability and aggregation of bovine liver glutamate dehydrogenase (GDH) upon heating at 50 °C or freeze–thawing was studied by dynamic light scattering, differential scanning calorimetry, analytical ultracentrifugation and circular dichroism spectroscopy. A freeze–thaw cycle resulted in the complete loss of the secondary and tertiary structure, and aggregation of GDH. All the cosolutes suppressed freeze–thaw- and heat-induced aggregation of GDH and increased the protein thermal stability. The effective concentrations of the cosolutes during freeze–thawing were lower than during heating. Sorbitol exhibited the highest anti-aggregation activity under freeze–thaw stress, whereas the most effective agents stabilizing the tertiary structure of GDH were HPCD and betaine. HPCD and trehalose were the most effective agents suppressing GDH thermal aggregation. All the chemical chaperones stabilized various soluble oligomeric forms of GDH against both types of stress. The data on GDH were compared with the effects of the same cosolutes on glycogen phosphorylase b during thermal and freeze–thaw-induced aggregation. This research can find further application in biotechnology and pharmaceutics. [ABSTRACT FROM AUTHOR]

Background: Glycogen storage disease type VI (GSD VI) is a rare disease in which liver glycogen metabolism is impaired by mutations in the glycogen phosphorylase L (PYGL). This study aimed to examine the clinical features, genetic analyses, and long-term outcomes of patients with GSD VI in Korea. Methods: From January 2002 to November 2022, we retrospectively reviewed patients diagnosed with GSD VI using a gene panel at Seoul National University Hospital. We investigated the clinical profile, liver histology, molecular diagnosis, and long-term outcomes of patients with GSD VI. Results: Five patients were included in the study. The age at onset was 18–30 months (median, 21 months), and current age was 3.7–17 years (median, 11 years). All patients showed hepatomegaly, elevated liver transaminase activity, and hypertriglyceridaemia. Hypercholesterolaemia and fasting hypoglycaemia occurred in 60% and 40% of patients, respectively. Ten variants of PYGL were identified, of which six were novel: five missense (p.[Gly607Val], p.[Leu445Pro], p.[Gly695Glu], p.[Val828Gly], p.[Tyr158His]), and one frameshift (p.[Arg67AlafsTer34]). All patients were treated with a high-protein diet, and four also received corn starch. All patients showed improved liver function tests, hypertriglyceridaemia, hepatomegaly, and height z score. Conclusions: The GSD gene panel is a useful diagnostic tool for confirming the presence of GSD VI. Genetic heterogeneity was observed in all patients with GSD VI. Increased liver enzyme levels, hypertriglyceridaemia, and height z score in patients with GSD VI improved during long-term follow-up. [ABSTRACT FROM AUTHOR]

Purpose: Derangements of liver transcriptional factors and enzymes have important implications in diabetes-induced related complications. Hence, this study which consists of two experimental phases was aimed at evaluating the possible underlying molecular mechanisms of intermittent fasting (IF), exercise starvation and honey in streptozotocin (STZ)-mediated liver damage in diabetic rats. Methods: The diabetic rats were treated orally with distilled water (0.5 ml/kg), IF, starvation and honey at 1 g/kg body weight in the non-diabetic phase for four (4) weeks. After STZ injections, four (4) weeks of IF, exercise, starvation, and honey therapy were used as interventions prior to a biochemical evaluation of the liver. Results: IF and exercise greatly decreased liver transcription factor (resistin, SREBP-1c), inflammatory cytokines/enzyme (TNF-α, IL-6, IL-1ß, MPO) as well as oxidative and nitrergic stress with correspondence increased liver PPAR-γ, IL-10, SOD, CAT and GSH in diabetic rats unlike starvation and honey regimen relative to diabetic controls. Furthermore, IF and exercise significantly improved hepatic glycogen synthase and decreased glycogen phosphorylase in diabetic rats compared to the diabetic control group, but starvation and honey therapy had no such influence. IF and exercise strategically reduces STZ-induced liver metabolic disorder via through modulation of liver transcriptional factors and inhibition of pro-inflammatory cytokines, oxido-nitrergic and adipokine signaling pathway. [ABSTRACT FROM AUTHOR]

Considerable evidence confirms the importance of Cyp26a1 to all-trans-retinoic acid (RA) homeostasis during embryogenesis. In contrast, despite its presence in postnatal liver as a potential major RA catabolizing enzyme and its acute sensitivity to induction by RA, some data suggested that Cyp26a1 contributes only marginally to endogenous RA homeostasis postnatally. We report reevaluation of a conditional Cyp26a1 knockdown in the postnatal mouse. The current results show that Cyp26a1 mRNA in WT mouse liver increases 16-fold upon refeeding after a fast, accompanied by an increased rate of RA elimination and a 41% decrease in the RA concentration. In contrast, Cyp26a1 mRNA in the refed homozygotic knockdown reached only 2% of its extent in WT during refeeding, accompanied by a slower rate of RA catabolism and no decrease in liver RA, relative to fasting. Refed homozygous knockdown mice also had decreased Akt1 and 2 phosphorylation and pyruvate dehydrogenase kinase 4 (Pdk4) mRNA and increased glucokinase (Gck) mRNA, glycogen phosphorylase (Pygl) phosphorylation, and serum glucose, relative to WT. Fasted homozygous knockdown mice had increased glucagon/insulin relative to WT. These data indicate that Cyp26a1 participates prominently in moderating the postnatal liver concentration of endogenous RA and contributes essentially to glucoregulatory control. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effects of cortisol on the regulation of the glycogen metabolism biomarkers glycogen synthase (GS) and glycogen phosphorylase (GP) in the glycogen-rich cells of the gills of tilapia (Oreochromis mossambicus). In the gills of tilapia, GP, GS, and glycogen were immunocytochemically colocalized in a specific group of glycogen-rich cells adjacent to the gills' main ionocytes and mitochondria-rich cells. Cortisol plays a vital role in the regulation of physiological functions in animals, including energy metabolism, respiration, immune response, and ion regulation. However, no studies have elucidated the mechanisms regulating cortisol and glycogen-rich cells in the gills. Therefore, we treated tilapia larvae with exogenous cortisol and a glucocorticoid receptor (GR) antagonist to investigate the regulatory mechanisms between cortisol and glycogen-rich cells in the gills. Our results showed that cortisol promoted the expression of gill glycogen phosphorylase isoform (GPGG) mRNA via GR, whereas the GS gene expression remained unaffected. We also found that GR mRNA was colocalized with some glycogen-rich cells in the gills, further confirming our hypothesis that cortisol directly acts on glycogen-rich cells in the gills of tilapia and regulates glycogen metabolism by promoting GPGG mRNA expression. [ABSTRACT FROM AUTHOR]

Glycogen phosphorylase (GP) is a key regulator of glucose levels and, with that, an important target for the discovery of novel treatments against type 2 diabetes. β-d-Glucopyranosyl derivatives have provided some of the most potent GP inhibitors discovered to date. In this regard, C-β-d-glucopyranosyl azole type inhibitors proved to be particularly effective, with 2- and 4-β-d-glucopyranosyl imidazoles among the most potent designed to date. His377 backbone C=O hydrogen bonding and ion–ion interactions of the protonated imidazole with Asp283 from the 280s loop, stabilizing the inactive state, were proposed as crucial to the observed potencies. Towards further exploring these features, 4-amino-3-(β-d-glucopyranosyl)-5-phenyl-1H-pyrazole (3) and 3-(β-d-glucopyranosyl)-4-guanidino-5-phenyl-1H-pyrazole (4) were designed and synthesized with the potential to exploit similar interactions. Binding assay experiments against rabbit muscle GPb revealed 3 as a moderate inhibitor (IC50 = 565 µM), but 4 displayed no inhibition at 625 µM concentration. Towards understanding the observed inhibitions, docking and post-docking molecular mechanics—generalized Born surface area (MM-GBSA) binding free energy calculations were performed, together with Monte Carlo and density functional theory (DFT) calculations on the free unbound ligands. The computations revealed that while 3 was predicted to hydrogen bond with His377 C=O in its favoured tautomeric state, the interactions with Asp283 were not direct and there were no ion–ion interactions; for 4, the most stable tautomer did not have the His377 backbone C=O interaction and while ion–ion interactions and direct hydrogen bonding with Asp283 were predicted, the conformational strain and entropy loss of the ligand in the bound state was significant. The importance of consideration of tautomeric states and ligand strain for glucose analogues in the confined space of the catalytic site with the 280s loop in the closed position was highlighted. [ABSTRACT FROM AUTHOR]

Type 2 diabetes (T2D) is associated with obesity and declining β-cells. L-glutamine has been implicated in the amelioration of T2D by virtue of its incretin secretagogue property while, there are mixed reports on pitavastatin's adiponectin potentiating ability. We aimed to investigate the effect of pitavastatin (P), L-glutamine (LG), and combination (P + LG) on glycemic control and β-cell regeneration in a high-fat diet (HFD) + streptozotocin (STZ)-induced T2D mouse model. C57BL6/J mice treated with HFD + STZ were divided into four groups: diabetes control (HFD + STZ), P, LG, and P + LG, while the control group (NCD) was fed with the normal-chow diet. Significant amelioration was observed in the combination therapy as compared to monotherapies in respect of (i) insulin resistance, glucose intolerance, lipid profile, adiponectin levels, and mitochondrial complexes I, II, and III activities, (ii) reduced phosphoenolpyruvate carboxykinase, glucose 6-phophatase, glycogen phosphorylase, and GLUT2 transcript levels with increased glycogen content in the liver, (iii) restoration of insulin receptor 1β, pAkt/Akt, and AdipoR1 protein levels in skeletal muscle, and (iv) significant increase in islet number due to β-cell regeneration and reduced β-cell death. L-glutamine and pitavastatin in combination can ameliorate T2D by inducing β-cell regeneration and regulating glucose homeostasis. [ABSTRACT FROM AUTHOR]

There are increasing concerns on the rising cases of diabetes mellitus with type 2 diabetes (T2D) being of major interest as well as the cost of its treatment. Plant phenolic compounds are natural and potent antioxidants that have been widely reported for their antidiabetic activities properties, one of which is ferulic acid. The effect of ferulic acid (FA) on major diabetogenic activities and pancreatic architecture linked to T2D was investigated in T2D rats. T2D was induced in male Sprague–Dawley rats using the fructose‐streptozotocin model. Diabetic rats were treated with FA at 150 or 300 mg/kg bodyweight (bw). Normal control consisted of rats administered with food and water, while diabetic control consisted of untreated diabetic rats. Metformin was used as the standard drug. The rats were humanely sacrificed after 5 weeks of treatment. Their blood, liver, and pancreas were collected for analysis. Total glycogen content and carbohydrate metabolic enzymes activities were analyzed in the liver, while the pancreas and serum from blood were analyzed for oxidative stress biomarkers, purinergic and cholinergic enzyme activities, and amylase and lipase activities. The pancreatic tissue was further subjected to microscopic and histological examinations. FA caused a significant (p < 0.05) decrease in blood glucose level, with concomitant increase in serum insulin level. Treatment with FA also led to elevated levels of GSH, HDL‐c, SOD, and catalase activities, while concomitantly suppressing malondialdehyde, cholesterol, triglyceride, LDL‐c, NO, ALT, AST, creatinine, urea, and uric acid levels, acetylcholinesterase, ATPase, ENTPDase, 5′‐nucleotidase, lipase, glycogen phosphorylase, glucose‐6‐phosphatase, and fructose‐1,6‐biphosphatase activities. Histology analysis revealed an intact pancreatic morphology in FA‐treated diabetic rats. While transmission electron microscopy (TEM) analysis revealed an intact pancreatic ultrastructure and increased number of insulin granules in β‐cells. Taken together, these results portray that the antidiabetic potentials of ferulic acid involves modulation of major diabetogenic activities and maintenance of the pancreatic ultrastructure architecture. [ABSTRACT FROM AUTHOR]

Glycogen is a polymerized form of glucose that serves as an energy reserve in all types of organisms. In animals glycogen synthesis and degradation, especially in liver and skeletal muscle, are regulated by hormonal and physiological signals that reciprocally control the opposing activities of glycogen synthase and glycogen phosphorylase. These enzymes are under allosteric control by binding of metabolites (e.g., ATP, AMP, G6P) and covalent control by reversible phosphorylation by kinase and phosphatase all assembled together on glycogen. More than 50 years ago Edmond Fischer and colleagues showed "flash activation" of phosphorylase in glycogen particles. This involved transient and extensive inhibition of protein phosphatase but even today the phenomenon is not understood. Phosphatase regulation is known to rely on regulatory subunits including glycogen binding subunits that serve as scaffolds, binding catalytic subunit, glycogen, and substrates. This tribute article to Edmond Fischer highlights his thoughts and ideas about the transient inhibition of phosphorylase phosphatase during flash activation of phosphorylase and speculates that phosphatase regulation in glycogen particles might involve a/b hybrids of phosphorylase. [ABSTRACT FROM AUTHOR]

Background: Osteoporosis (OP) is a major and growing public health problem characterized by decreased bone mineral density and destroyed bone microarchitecture. Previous studies found that Lycium Chinense Mill (LC) has a potent role in inhibiting bone loss. Kukoamine A (KuA), a bioactive compound extract from LC was responsible for the anti-osteoporosis effect. This study aimed to investigate the anti-osteoporosis effect of KuA isolated from LC in treating OP and its potential molecular mechanism. Method: In this study, network pharmacology and molecular docking were investigated firstly to find the active ingredients of LC such as KuA, and the target genes of OP by the TCMSP platform. The LC-OP-potential Target gene network was constructed by the STRING database and network maps were built by Cytoscape software. And then, the anti-osteoporotic effect of KuA in OVX-induced osteoporosis mice and MC3T3-E1 cell lines were investigated and the potential molecular mechanism including inflammation level, cell apoptosis, and oxidative stress was analyzed by dual-energy X-ray absorptiometry (DXA), micro-CT, ELISA, RT-PCR, and Western Blotting. Result: A total of 22 active compounds were screened, and we found KuA was identified as the highest active ingredient. Glycogen Phosphorylase (PYGM) was the target gene associated with a maximum number of active ingredients of LC and regulated KuA. In vivo, KuA treatment significantly increased the bone mineral density and improve bone microarchitecture for example increased BV/TV, Tb.N and Tb.Th but reduced Tb.Sp in tibia and lumber 4. Furthermore, KuA increased mRNA expression of osteoblastic differentiation-related genes in OVX mice and protects against OVX-induced cell apoptosis, oxidative stress level and inflammation level. In vitro, KuA significantly improves osteogenic differentiation and mineralization in cells experiment. In addition, KuA also attenuated inflammation levels, cell apoptosis, and oxidative stress level. Conclusion: The results suggest that KuA could protect against the development of OP in osteoblast cells and ovariectomized OP model mice and these found to provide a better understanding of the pharmacological activities of KuA again bone loss. [ABSTRACT FROM AUTHOR]

Glycogen and starch metabolism require the initial synthesis of glucose-1-phosphate (G1P) from glucose-6-phosphate (G6P), a reaction catalysed by the bi-directional enzyme phosphoglucomutase (PGM). Keywords: Cyanobacteria; glycogen; phosphoglucomutase; starch; Synechocystis EN Cyanobacteria glycogen phosphoglucomutase starch Synechocystis 1293 1296 4 03/15/23 20230313 NES 230313 Phosphoglucomutase (PGM) has recently gained attention as a key regulatory point in the metabolism of carbon storage compounds. Overexpression of PGM/PMM reverted the metabolite concentrations to the wild-type levels, confirming that the increased levels of G1P and G6P in the PGM mutant were caused by the low phosphoglucomutase activity of PGM/PMM. In I Synechocystis i , two enzymes are capable of carrying out the phosphoglucomutase reaction: Sll0726 (PGM), which is responsible for 99% of the phosphoglucomutase activity, and Slr1334 (PGM/PMM). [Extracted from the article]

Background: Artificial microbial consortia composed of heterotrophic and photoautotrophic organisms represent a unique strategy for converting light energy and carbon dioxide into high-value bioproducts. Currently, the types of desired bioproducts are still limited, and microbial fitness benefit rendered by paired partner generally needs to be intensified. Exploring novel artificial microbial consortia at a laboratory scale is an essential step towards addressing this unmet need. This study aimed to conduct and analyze an artificial consortium composed of cyanobacterium Synechococcus elongatus FL130 with the filamentous fungus Aspergillus nidulans TWY1.1 for producing fungi-derived secondary metabolite of polyketide neosartoricin B. Results: Polyketide-producing A. nidulans TWY1.1 substantially ameliorated the growth and the survival of sucrose-secreting cyanobacterium S. elongatus FL130 in salt-stressed environments. Besides sucrose, comparable amounts of other carbohydrates were released from axenically cultured FL130 cells, which could be efficiently consumed by TWY1.1. Relative to axenically cultured FL130, less glycogen was accumulated in FL130 cells co-cultured with TWY1.1, and the glycogen phosphorylase gene catalyzing the first step for glycogen degradation had two-fold expression. Different from axenically cultured filamentous fungi, abundant vacuoles were observed in fungal hyphae of TWY1.1 co-cultured with cyanobacterium FL130. Meanwhile, FL130 cells displayed a characteristic pattern of interacting with its heterotrophic partner, densely dispersing along certain hyphae of TWY1.1. Finally, polyketide neosartoricin B was produced from TWY1.1 in FL130-TWY1.1 co-cultures, which was tightly adjusted by nitrogen level. Conclusion: Overall, the results thoroughly proved the concept of pairing cyanobacteria with filamentous fungi to build artificial consortia for producing fungi-derived biomolecules. [ABSTRACT FROM AUTHOR]

Brain-type glycogen phosphorylase (PYGB) inhibitors are recognized as prospective drugs for treating ischemic brain injury. We previously reported compound 1 as a novel glycogen phosphorylase inhibitor with brain-protective properties. In this study, we validated whether PYGB could be used as the therapeutic target for hypoxic-ischemic diseases and investigated whether compound 1 exerts a protective effect against astrocyte hypoxia/reoxygenation (H/R) injury by targeting PYGB. A gene-silencing strategy was initially applied to downregulate PYGB proteins in mouse astrocytes, which was followed by a series of cellular experiments with compound 1. Next, we compared relevant indicators that could prove the protective effect of compound 1 on brain injury, finding that after PYGB knockdown, compound 1 could not obviously alleviate astrocytes H/R injury, as evidenced by cell viability, which was not significantly improved, and lactate dehydrogenase (LDH) leakage rate, intracellular glucose content, and post-ischemic reactive oxygen species (ROS) level, which were not remarkably reduced. At the same time, cellular energy metabolism did not improve, and the degree of extracellular acidification was not downregulated after administration of compound 1 after PYGB knockdown. In addition, it could neither significantly increase the level of mitochondrial aerobic energy metabolism nor inhibit the expression of apoptosis-associated proteins. The above results indicate that compound 1 could target PYGB to exert its protective effect against cellular H/R injury in mouse astrocytes. Simultaneously, we further demonstrated that PYGB could be an efficient therapeutic target for ischemic-hypoxic diseases. This study provides a new reference for further in-depth study of the action mechanism of the efficacy of compound 1. [ABSTRACT FROM AUTHOR]

Cardiovascular abnormalities have been reported as a major contributor of diabetic mortality. The protective effect of ferulic acid on diabetic cardiomyopathy in fructose‐streptozotocin induced type 2 diabetes (T2D) rat model was elucidated in this study. Type 2 diabetic rats were treated by oral administration of low (150 mg/kg b.w) and high (300 mg/kg b.w) doses of ferulic acid. Metformin was used as the antidiabetic drug. Rats were humanely euthanized after 5 weeks of treatment, and their blood and hearts were collected. Induction of T2D depleted the levels of reduced glutathione, glycogen, and HDL‐cholesterol and the activities of superoxide dismutase, catalase, ENTPDase, and 5′nucleotidase. It simultaneously triggered increase in the levels of malondialdehyde, total cholesterol, triglyceride, LDL‐cholesterol, creatinine kinase‐MB as well as activities of acetylcholinesterase, angiotensin converting enzyme (ACE), ATPase, glucose‐6‐phopsphatase, fructose‐1,6‐bisphophatase, glycogen phosphorylase, and lipase. T2D induction further revealed an obvious degeneration of cardiac muscle morphology. However, treatment with ferulic acid markedly reversed the levels and activities of these biomarkers with concomitant improvement in myocardium structural morphology, which had favorable comparison with the standard drug, metformin. Additionally, T2D induction led to the depletion of 40%, 75%, and 33% of fatty acids, fatty esters, and steroids, respectively, with concomitant generation of eicosenoic acid, gamolenic acid, and vitamin E. Ferulic acid treatment restored eicosanoic acid, 2‐hydroxyethyl ester, with concomitant generation of 6‐octadecenoic acid, (Z)‐, cis‐11‐eicosenoic acid, tridecanedioic acid, octadecanoic acid, 2‐hydroxyethyl ester, ethyl 3‐hydroxytridecanoate, dipalmitin, cholesterol isocaproate, cholest‐5‐ene, 3‐(1‐oxobuthoxy)‐, cholesta‐3,5‐diene. These results suggest the cardioprotective potential of ferulic acid against diabetic cardiomyopathy. [ABSTRACT FROM AUTHOR]

The plasma membrane glucose transporter-2 (GLUT2) monitors brain cell uptake of the critical nutrient glucose, and functions within astrocytes of as-yet-unknown location to control glucose counter-regulation. Hypothalamic astrocyte-neuron metabolic coupling provides vital cues to the neural glucostatic network. Current research utilized an established hypothalamic primary astrocyte culture model along with gene knockdown tools to investigate whether GLUT2 imposes sex-specific regulation of glucose/energy sensor function and glycogen metabolism in this cell population. Data show that GLUT2 stimulates or inhibits glucokinase (GCK) expression in glucose-supplied versus -deprived male astrocytes, but does not control this protein in female. Astrocyte 5'-AMP-activated protein kinaseα1/2 (AMPK) protein is augmented by GLUT2 in each sex, but phosphoAMPKα1/2 is coincidently up- (male) or down- (female) regulated. GLUT2 effects on glycogen synthase (GS) diverges in the two sexes, but direction of this control is reversed by glucoprivation in each sex. GLUT2 increases (male) or decreases (female) glycogen phosphorylase-brain type (GPbb) protein during glucoprivation, yet simultaneously inhibits (male) or stimulates (female) GP-muscle type (GPmm) expression. Astrocyte glycogen accumulation is restrained by GLUT2 when glucose is present (male) or absent (both sexes). Outcomes disclose sex-dependent GLUT2 control of the astrocyte glycolytic pathway sensor GCK. Data show that glucose status determines GLUT2 regulation of GS (both sexes), GPbb (female), and GPmm (male), and that GLUT2 imposes opposite control of GS, GPbb, and GPmm profiles between sexes during glucoprivation. Ongoing studies aim to investigate molecular mechanisms underlying sex-dimorphic GLUT2 regulation of hypothalamic astrocyte metabolic-sensory and glycogen metabolic proteins, and to characterize effects of sex-specific astrocyte target protein responses to GLUT2 on glucose regulation. [ABSTRACT FROM AUTHOR]

The purpose of this study was to see how chrysin and/or bone marrow-derived mesenchymal stem cells (BM-MSCs) affected streptozotocin (STZ)/nicotinamide (NA)-induced diabetic rats as an animal model of type 2 diabetes mellitus (T2DM). Male Wistar rats were given a single intraperitoneal (i.p.) injection of 60 mg STZ/kg bodyweight (bw) 15 min after an i.p. injection of NA (120 mg/kg bw) to induce T2DM. The diabetic rats were given chrysin orally at a dose of 100 mg/kg bw every other day, BM-MSCs intravenously at a dose of 1 × 106 cells/rat/week, and their combination for 30 days after diabetes induction. The rats in the diabetic group displayed impaired oral glucose tolerance and a decrease in liver glycogen content and in serum insulin, C-peptide, and IL-13 levels. They also had significantly upregulated activities in terms of liver glucose-6-phosphatase and glycogen phosphorylase and elevated levels of serum free fatty acids, IL-1β, and TNF-α. In addition, the diabetic rats exhibited a significant elevation in the adipose tissue resistin protein expression level and a significant decrease in the expression of adiponectin, insulin receptor-beta subunit, insulin receptor substrate-1, and insulin receptor substrate-2, which were associated with a decrease in the size of the pancreatic islets and in the number of β-cells and insulin granules in the islets. The treatment of diabetic rats with chrysin and/or BM-MSCs significantly improved the previously deteriorated alterations, with chrysin combined with BM-MSCs being the most effective. Based on these findings, it can be concluded that combining chrysin with BM-MSCs produced greater additive therapeutic value than using them separately in NA/STZ-induced T2DM rats. [ABSTRACT FROM AUTHOR]

Although the presence of glycogen in platelets was established in the 1960s, its importance to specific functions (i.e., activation, secretion, aggregation, and clot contraction) remains unclear. Patients with glycogen storage disease often present with increased bleeding and glycogen phosphorylase (GP) inhibitors, when used as treatments for diabetes, induce bleeding in preclinical studies suggesting some role for this form of glucose in hemostasis. In the present work, we examined how glycogen mobilization affects platelet function using GP inhibitors (CP316819 and CP91149) and a battery of ex vivo assays. Blocking GP activity increased glycogen levels in resting and thrombin-activated platelets and inhibited platelet secretion and clot contraction, with minimal effects on aggregation. Seahorse energy flux analysis and metabolite supplementation experiments suggested that glycogen is an important metabolic fuel whose role is affected by platelet activation and the availability of external glucose and other metabolic fuels. Our data shed light on the bleeding diathesis in glycogen storage disease patients and offer insights into the potential effects of hyperglycemia on platelets. What did we know? Activated platelets transition from a low-energy-requiring, resting state to a high-energy-demanding state. Platelet glycogen is degraded upon activation. Glycogen storage disorders and glycogen phosphorylase inhibitors are associated with bleeding. What did we discover? Glycogen turnover occurs in resting platelets and its degradation is important for platelet functions. Glycogen phosphorylase inhibitors block secretion and clot contraction of which the latter can be reversed with alternative metabolic fuels. Glucose derived from glycogen may be routed through TCA/OxPhos versus aerobic glycolysis. What is the impact? Glycogen breakdown contributes to the high energy requirements of platelet function. Our work offers insights into potential energy sources in activated platelets. [ABSTRACT FROM AUTHOR]

Formation and accumulation of protein aggregates adversely affect intracellular processes in living cells and are negative factors in the production and storage of protein preparations. Chemical chaperones can prevent protein aggregation, but this effect is not universal and depends on the target protein structure and kinetics of its aggregation. We studied the effect of betaine (Bet) and lysine (Lys) on thermal aggregation of muscle glycogen phosphorylase b (Phb) at 48°C (aggregation order, n = 0.5), UV-irradiated Phb (UV-Phb) at 37°C (n = 1), and apo-form of Phb (apo-Phb) at 37°C (n = 2). Using dynamic light scattering, differential scanning calorimetry, and analytical ultracentrifugation, we have shown that Bet protected Phb and apo-Phb from aggregation, but accelerated the aggregation of UV-Phb. At the same time, Lys prevented UV-Phb and apo-Phb aggregation, but increased the rate of Phb aggregation. The mechanisms of chemical chaperone action on the tertiary and quaternary structures and kinetics of thermal aggregation of the target proteins are discussed. Comparison of the effects of chemical chaperones on the proteins with different aggregation kinetics provides more complete information on the mechanism of their action. [ABSTRACT FROM AUTHOR]

In this paper, we studied the structure, expression and function of black carp insulin gene. The complete Mylopharyngodon piceus insulin (Mp-Ins) gene is 1,965 bp long and includes a 1,499 bp 5'-untranslated region (UTR), a 139 bp 3' -UTR with a poly(A) tail, and an open reading frame (ORF) of 327 bp. The predicted molecular weight of the recombinant Mp-Ins(rMp-Ins) protein is 11.87 kDa. The mRNA expression of Mp-Ins is upregulated in the brain and liver. After the injection of rMp-Ins, Mp-Ins mRNA transcript abundance was significantly upregulated in the liver. The rMp-Ins protein could inhibit the concentration of glycogen phosphorylase (GP), growth hormone (GH), fatty acid synthase (FAS), and insulin-like growth factors-1 (IGF-1), and it also signifi- cantly increased the concentration of PI3K. Additionally, the injection of rMp-Ins did not have a significant impact on the glucose-6-phosphatase (G6Pase) content in blood. In situ hybridization results showed that the positive signal of the Mp-Ins gene was mainly concentrated in the cell nucleus of brain tissue and the cell membrane of liver tissue and muscle tissue. Together, these results demonstrated that Mp-Ins plays an important role in growth and metabolism in M. piceus. [ABSTRACT FROM AUTHOR]

Fish can go through periods of feed deprivation, either due to natural causes influenced by temperature or management techniques in animal production, affecting their energy metabolism differently, depending on the duration of fasting in days and water temperature. This study showed the effect of different days of fasting before slaughter in rainbow trout by analyzing the intermediary metabolic enzymes in the muscle and liver. For this purpose, a non-fasting group was compared with trout that fasted for 5, 10, and 20 days (55, 107, and 200 degree days (°C d), respectively). A first phase of increased activity of enzymes involved in glycolysis was observed, increasing hexokinase enzyme activity in muscle and pyruvate kinase enzyme activity in muscle and liver. As the fasting days progressed, enzymes involved in the gluconeogenic and glycogenolytic pathways in the liver such as lactate dehydrogenase and glycogen phosphorylase increased their activity regarding the no fasted group. After 20 days of fasting (200 °C d), lipogenic and protein related enzyme activity depletion was observed, leading to significant changes in energy metabolism. Therefore, prolonged fasting with high degree days duration may compromise the energy supply for the vital development of rainbow trout. [ABSTRACT FROM AUTHOR]

Background: Myocardial ischemia, the most common kind of cardiovascular disease, and the leading cause of mortality worldwide. It is caused mostly by cardiac muscle necrosis caused by an abrupt coronary artery occlusion. Smoking and obesity are two major risk factors for myocardial infarction. Chest pain and dyspnea are common symptoms caused by a reduction in blood flow to the myocardium. Objective: glycogen (GP) modulates glucose metabolism by mobilizing intracellular glycogen. Heart and brain tissues express it, which generates energy during muscle contraction. Myocardial ischemia activates Glycogen phosphorylase BB, which promotes glycogen breakdown. Subjects and Methods: A case-control study was used in this investigation. These investigations comprise 160 Iraqi volunteers ranging in age from 25 to 75 years (50 with ST-elevation, 50 without ST-elevation, and 60 in the normal healthy control group). Results: Glycogen phosphorylase BB (GPBB) Activity by spectrophotometer technique. There were significant differences in GPBB activity among the groups the mean of GPBB for Control (3.25± 0.97) was significantly smaller than for both STEMI (12.54± 2.85), p < .001 and non ST-elevation myocardial infarction (NSTEMI) (6.51± 0.73), p < .001. The mean of GPBB for ST-elevation myocardial infarction (STEMI) (12.54± 2.88) was significantly larger than for NSTEMI (6.51± 0.73), p < .001. A significant negative correlation was observed between GPBB and high sensitive troponin I (hs-troponin I) and a negative correlation was observed between GPBB and TC in the NSTEMI group. Conclusion: higher serum glycogen phosphorylase levels with higher troponin I levels were both observed in myocardial infarction patients and there was a significant correlation between them. [ABSTRACT FROM AUTHOR]

Astrocyte glycogen is a critical metabolic variable that affects hypothalamic control of glucostasis. Glucocorticoid hormones regulate peripheral glycogen, but their impact on hypothalamic glycogen is not known. A hypothalamic astrocyte primary culture model was used to investigate the premise that glucocorticoids impose sex-dimorphic independent and interactive control of glycogen metabolic enzyme protein expression and glycogen accumulation. The glucocorticoid receptor (GR) agonist dexamethasone (DEX) down-regulated glycogen synthase (GS), glycogen phosphorylase (GP)–brain type (GPbb), and GP–muscle type (GPmm) proteins in glucose-supplied male astrocytes, but enhanced these profiles in female. The catecholamine neurotransmitter norepinephrine (NE) did not alter these proteins, but amplified DEX inhibition of GS and GPbb in male or abolished GR stimulation of GPmm in female. In both sexes, DEX and NE individually increased glycogen content, but DEX attenuated the magnitude of noradrenergic stimulation. Glucoprivation suppressed GS, GPbb, and GPmm in male, but not female astrocytes, and elevated or diminished glycogen in these sexes, respectively. Glucose-deprived astrocytes exhibit GR-dependent induced glycogen accumulation in both sexes, and corresponding loss (male) or attenuation (female) of noradrenergic-dependent glycogen build-up. Current evidence for GR augmentation of hypothalamic astrocyte glycogen content in each sex, yet divergent effects on glycogen enzyme proteins infers that glucocorticoids may elicit opposite adjustments in glycogen turnover in each sex. Results document GR modulation of NE stimulation of glycogen accumulation in the presence (male and female) or absence (female) of glucose. Outcomes provide novel proof that astrocyte energy status influences the magnitude of GR and NE signal effects on glycogen mass. [ABSTRACT FROM AUTHOR]

Glycerol and aquaporin 9 (aquaglyceroporin) are known to be involved in freeze tolerance in the Japanese tree frog Hyla japonica. However, the regulatory mechanisms of freeze tolerance in this species have not been fully elucidated. In the present study, we focused on the inter‐ and intracellular dynamics of glucose to analyze the role of glucose and glucose‐related proteins such as transporter and metabolic enzymes in freeze tolerance. Serum glucose concentrations were compared among the frogs that were nonhibernating, hibernating, and thawed after freezing at −4°C for 6 hr. Serum concentrations of glucose in thawed frogs were significantly higher than those in hibernating and nonhibernating, active frogs. Periodic acid–Schiff staining showed that the accumulation of glycogen in the hepatocytes increased before hibernation and decreased after freezing and thawing. Quantitative RT‐PCR analysis using the liver showed that, compared with active frogs, the type 2 glucose transporter gene (glut2) was upregulated in frozen frogs, the liver glycogen phosphorylase gene (pygl) was upregulated in frozen or thawed frogs, and the type 2 glycogen synthase gene (gys2) was upregulated in hibernating frogs. Immunohistochemistry of liver sections showed that, compared with nonhibernating frogs, Glut2 proteins were clearly increased most likely on the plasma membrane of hepatocytes in hibernating frogs and further increased by freezing, then decreased after thawing. These results suggest the possibility that glucose acts as a cryoprotectant in H. japonica. [ABSTRACT FROM AUTHOR]

The purpose of this review is to summarize drugs containing an azoloazine moiety and exhibiting antidiabetic activity. The review includes azoloazines active against dipeptidyl peptidase-4, α-glucosidase, and glycogen phosphorylase acting as PPARγ and GPR119 receptor agonists, as well as those inhibiting advanced glycation. [ABSTRACT FROM AUTHOR]

Glycosylidene-spiro-morpholin(on)es are scarcely described skeletons in the literature. In this work, we have systematically explored the synthetic routes towards such morpholinones based on the reactions of O-peracylated hept-2-ulopyranosonamide derivatives of D-gluco and D-galacto configuration. Koenigs–Knorr type glycosylation of 2-chloroethanol, allylic and propargylic alcohols by (glyculosylbromide)onamides furnished the expected glycosides. The 2-chloroethyl glycosides were ring closed to the corresponding spiro-morpholinones by treatment with K2CO3. The (allyl glyculosid)onamides gave diastereomeric mixtures of spiro-5-hydroxymorpholinones by ozonolysis and 5-iodomethylmorpholinones under iodonium ion mediated conditions. The ozonolytic method has not yet been known for the construction of morpholine rings, therefore, it was also extended to O-allyl mandelamide. The 5-hydroxymorpholinones were subjected to oxidation and acid catalyzed elimination reactions to give the corresponding morpholine-3,5-dions and 5,6-didehydro-morpholin-3-ones, respectively. Base induced elimination of the 5-iodomethylmorpholinones gave 5-methyl-2H-1,4-oxazin-3(4H)-ones. O-Acyl protecting groups of all of the above compounds were removed under Zemplén conditions. Some of the D-gluco configured unprotected compounds were tested as inhibitors of glycogen phosphorylase, but showed no significant effect. [ABSTRACT FROM AUTHOR]

McArdle disease is a rare autosomal recessive disorder caused by mutations in the PYGM gene. This gene encodes for the skeletal muscle isoform of glycogen phosphorylase (myophosphorylase), the first enzyme in glycogenolysis. Patients with this disorder are unable to obtain energy from their glycogen stored in skeletal muscle, prompting an exercise intolerance. Currently, there is no treatment for this disease, and the lack of suitable in vitro human models has prevented the search for therapies against it. In this article, we have established the first human iPSC-based model for McArdle disease. For the generation of this model, induced pluripotent stem cells (iPSCs) from a patient with McArdle disease (harbouring the homozygous mutation c.148C>T; p.R50* in the PYGM gene) were differentiated into myogenic cells able to contract spontaneously in the presence of motor neurons and generate calcium transients, a proof of their maturity and functionality. Additionally, an isogenic skeletal muscle model of McArdle disease was created. As a proof-of-concept, we have tested in this model the rescue of PYGM expression by two different read-through compounds (PTC124 and RTC13). The developed model will be very useful as a platform for testing drugs or compounds with potential pharmacological activity. [ABSTRACT FROM AUTHOR]

Motor neurons in the spinal cord are essential for movement. During the embryonic period, developing motor neurons store glycogen to protect against hypoglycemic and hypoxic stress. However, the mechanisms by which glycogen metabolism is regulated in motor neurons remain unclear. We herein investigated the transcriptional regulation of genes related to glycogen metabolism in the developing spinal cord. We focused on the regulatory mechanism of glycogen synthase (Gys1) and glycogen phosphorylase brain isoform (PygB), which play central roles in glycogen metabolism, and found that the transcription factor STAT3 regulated the expression of Gys1 and PygB via cis‐regulatory promoter sequences in the developing spinal cord. These results suggest that STAT3 is important for the regulation of glycogen metabolism during motor neuron development. [ABSTRACT FROM AUTHOR]