Glycogen Accumulation Research Articles

In Vivo Glucose Transporter-2 Regulation of Dorsomedial Versus Ventrolateral VMN Astrocyte Metabolic Sensor and Glycogen Metabolic Enzyme Gene Expression in Female Rat.

Astrocyte glycogenolysis shapes ventromedial hypothalamic nucleus (VMN) regulation of glucostasis in vivo. Glucose transporter-2 (GLUT2), a plasma membrane glucose sensor, controls hypothalamic primary astrocyte culture glycogen metabolism in vitro. In vivo gene silencing tools and single-cell laser-catapult-microdissection/multiplex qPCR techniques were used here to examine whether GLUT2 governs dorsomedial (VMNdm) and/or ventrolateral (VMNvl) VMN astrocyte metabolic sensor and glycogen metabolic enzyme gene profiles. GLUT2 gene knockdown diminished astrocyte GLUT2 mRNA in both VMN divisions. Hypoglycemia caused GLUT2 siRNA-reversible up-regulation of this gene profile in the VMNdm, but down-regulated VMNvl astrocyte GLUT2 transcription. GLUT2 augmented baseline VMNdm and VMNvl astrocyte glucokinase (GCK) gene expression, but increased (VMNdm) or reduced (VMNvl) GCK transcription during hypoglycemia. GLUT2 imposed opposite control, namely stimulation versus inhibition of VMNdm or VMNvl astrocyte 5'-AMP-activated protein kinase-alpha 1 and -alpha 2 gene expression, respectively. GLUT2 stimulated astrocyte glycogen synthase (GS) gene expression in each VMN division. GLUT2 inhibited transcription of the AMP-sensitive glycogen phosphorylase (GP) isoform GP-brain type (GPbb) in each site, yet diminished (VMNdm) or augmented (VMNvl) astrocyte GP-muscle type (GPmm) mRNA. GLUT2 enhanced VMNdm and VMNvl glycogen accumulation during euglycemia, and curbed hypoglycemia-associated VMNdm glycogen depletion. Results show that VMN astrocytes exhibit opposite, division-specific GLUT2 transcriptional responsiveness to hypoglycemia. Data document divergent GLUT2 control of GCK, AMPK catalytic subunit, and GPmm gene profiles in VMNdm versus VMNvl astrocytes. Ongoing studies seek to determine how differential GLUT2 regulation of glucose and energy sensor function and glycogenolysis in each VMN location may affect local neuron responses to hypoglycemia.

Global birth prevalence of Pompe disease: A systematic review and meta-analysis

BackgroundPompe disease, also known as Glycogen storage disease type II, is an autosomal recessive disorder caused by defects in alpha-glucosidase, resulting in abnormal glycogen accumulation. MethodsTo conduct a systematic review and meta-analysis of birth prevalence of Pompe disease, the MEDLINE and EMBASE databases were searched for original research articles on the epidemiology of Pompe disease from inception until July 01, 2024. Meta-analysis was performed to estimate global birth prevalence of Pompe disease. The funnel plot was used to describe potential publication bias. ResultsTwenty-two studies, screened out of 945 records, were included for data extraction. Studies that fulfilled inclusion criteria involved 15 areas/countries. Global birth prevalence of Pompe disease was 2.0 cases (95% CI: 1.5–2.4) per 100,000 live births. Global birth prevalence of infantile-onset Pompe disease was 1.0 cases (95% CI: 0.5–1.5) per 100,000 live births. Global birth prevalence of late-onset Pompe disease was 2.4 cases (95% CI: 1.8–3.0) per 100,000 live births. The main limitations are that no study was assessed as high-quality and approximately half of the studies were from Europe. ConclusionsQuantitative data on the global epidemiology of Pompe disease could be the fundamental to evaluate the global efforts on building a better world for Pompe disease patients.

HNF4α-CDKL3 axis restricts MASLD progression by targeting FoxO1 via non-canonical phosphorylation

Background and Aims: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a worldwide disease with a broad spectrum of symptoms. Though being mild at early stages, further development of MASLD causes steatohepatitis, cirrhosis, liver cancers and accompanied diabetes. Discovery of the critical regulators in MASLD progression hold great values in both basic and translational medicine. Approach and Results: Herein, we identified Cyclin-dependent kinase like 3 (CDKL3) as a primary guardian against MASLD progression. Mice with liver-specific Cdkl3 ablation developed severe MASLD-related hepatic inflammation, fibrosis and diabetes. Mechanism-wise, CDKL3 directly phosphorylates FoxO1 on an unconventional site for the ubiquitination-dependent degradation of FoxO1, thereby remarkably alleviating glycogen and lipid accumulation and essentially preventing the onset of higher MASLD stages. Moreover, hepatic CDKL3 is a direct target gene of HNF4α. HNF4α is inhibited during MASLD, which led to diminished CDKL3 expression. The CDKL3-mediated crosstalk of HNF4α and FoxO1 hence forms a feedback loop in MASLD progression. Conclusions: We unearthed an alternative but critical regulatory path of FoxO1 by HNF4α-CDKL3 axis. CDKL3 serves as a guardian against MASLD and also may function as a prognosis indicator of FoxO1 inhibitor in MASLD treatment.

Gastrodin ameliorates diabetic nephropathy by activating the AMPK/Nrf2 pathway.

Diabetic nephropathy (DN) is a leading cause of end-stage kidney failure, contributing to elevated morbidity and mortality rates in individuals with diabetes. Despite its potential renoprotective effects, the molecular mechanism by which gastrodin (GSTD) impacts DN remains unclear. To investigate this, mice were initially induced with DN via intraperitoneal streptozotocin (STZ) injection (50mg/kg) and subsequently treated with varying doses of GSTD (5, 10, 20mg/kg). Furthermore, the potential molecular mechanism of GSTD in mitigating DN was explored in vivo in conjunction with compound C, an inhibitor of 5'-AMP-activated protein kinase (AMPK). Subsequently, the blood weight, fasting blood glucose levels, and renal injury markers of DN-afflicted mice were assessed. Additionally, renal tissues were subjected to quantitative reverse-transcriptase-polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) to evaluate inflammatory factor levels, colorimetric assays to measure renal malondialdehyde (MDA) levels, and immunoblotting analysis to examine AMPK/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. The results demonstrated that a 6-week GSTD regimen effectively improved metabolic manifestations associated with DN, including reductions in fasting blood glucose levels, 24-hour urine output, renal indices, amelioration of glomerular histopathological abnormalities, diminished glycogen accumulation, and fibrosis. Furthermore, DN-afflicted renal tissues exhibited decreased MDA levels and elevated expression of AMPK/Nrf2 pathway-associated proteins. The beneficial effects of GSTD on DN and its protein modulation were reversed upon co-intervention with compound C. Together, our findings imply that GSTD improves DN by activating the AMPK/Nrf2 pathway, thereby mitigating STZ-induced renal damage, inflammatory responses, and oxidative stress.

Clinical analysis and follow-up results of 25 children with glycogen storage disease

Objective: To investigate the clinical characteristics, genetic characteristics and follow-up of hepatic glycogen accumulation in order to further improve the prognosis of children with hepatic glycogen accumulation. Methods: Clinical data of hospitalized children diagnosed with hepatic glycogen accumulation disease in the Department of gastroenterology, Children's Hospital Affiliated to Capital Institute of Pediatrics from January 2010 to April 2023 were collected and retrospectively analyzed. The results of laboratory examination and gene sequencing were analyzed, and the patients with more than 3 cases (n) were grouped according to the genetic results: Group 1 was type Ⅰ (n=8), group 2 was type Ⅲ (n=5), and group 3 was type Ⅸ a (n=8). The growth, development and prognosis of the children were followed up, and the related clinical characteristics of pediatric hepatic glycogen accumulation were summarized. Results: A total of 25 children with hepatic accumulation of glycogen were included in the study, including 15 males and 10 females. The mean age of diagnosis was (29.1±13.5) months. There were 12 cases (48%) with varying degrees of hypoglycemia, and 2 cases (8%) with severe hypoglycemia. There were 19 cases with height retardation (76%), 4 cases with anemia (16%), 3 cases with proteinuria (12%), and 1 case with cholestasis (4%). The genetic results showed that there were 4 cases of type Ⅰ a (16%), 4 cases of type Ⅰ b (16%), 1 case of type Ⅱ (4%), 5 cases of type Ⅲ (20%), 2 cases of type Ⅳ (8%), 1 case of type Ⅵ (4%), and 8 cases of type Ⅸ (32%). By analyzing the three subgroups, there were statistically significant differences in uric acid and triglyceride (P<0.05), while there were no statistically significant differences in aminotransferase levels, fasting blood glucose, lactic acid, cholesterol and low density lipoprotein levels (P>0.05). The height-specific age Z scores of the three groups were compared, which were -2.86±1.62, -1.46±1.06 and -1.83±0.98, respectively. After at least 1 year of follow-up, the growth and development of groups 2 and 3 were significantly improved compared with group 1 (P<0.05), and the Z scores were -2.28±1.07, 0.20±1.54 and 0.10±1.44. After more than 1 year of follow-up, all the children with type IX had stopped using raw corn starch and had normal transaminase. 4 patients with type Ia were taking raw corn starch orally regularly. Aminotransferase, uric acid and lactic acid were normal, and hypoglycemia was detected among them.Among the 4 cases of type Ⅰb, 1 case had recurrent respiratory and intestinal infections, and 2 cases had Crohn's disease.4 cases of type Ⅲ had stopped using raw corn starch and adopted high protein and low carbohydrate diet. The aminotransferase was normal except for high creatine kinase. One case of type Ⅵ died of liver failure.2 cases were type Ⅳ, 1 died and 1 had a slightly elevated transaminase level. Conclusion: When it is found that the children have liver enlargement, elevated aminotransferase, fasting hypoglycemia, and backward growth and development, it is necessary to be vigilant about liver glycogen accumulation.Clinical manifestations, biochemical indicators combined with genetic examination are helpful for the diagnosis of hepatic glycogen accumulation. Meanwhile, nutritional management is targeted according to the metabolic characteristics of different subtypes, and attention is paid to growth and development.

Tubular glycogen accumulation in acute kidney injury associated with red yeast rice supplement

Tubular glycogen accumulation in acute kidney injury associated with red yeast rice supplement

First-in-Human Evaluation of Safety, Pharmacokinetics and Muscle Glycogen Lowering of a Novel Glycogen Synthase 1 Inhibitor for the Treatment of Pompe Disease.

Pompe disease is a rare glycogen storage disease caused by mutations in the enzyme acid α-glucosidase (GAA) resulting in pathological accumulation of glycogen in muscle tissues leading to progressive weakness and respiratory dysfunction. Enzyme replacement therapy (ERT) with GAA is currently the sole treatment option for patients with Pompe disease. ERT burdens patients with frequent intravenous infusions while insufficiently halting disease progression due to incomplete ERT skeletal muscle distribution. Glycogen synthase 1 (GYS1) has been proposed as a substrate reduction therapy (SRT) target for Pompe disease. Here, we report results from the first-in-human study of the orally available GYS1 inhibitor MZE001 in healthy subjects. In 88 participants, MZE001 was well-tolerated up to a single dose of 480 mg BID and multiple doses of 720 mg BID for 10 days. Noncompartmental analysis determined that the half-life and Ctrough concentrations of MZE001 could provide efficacious exposures with once or twice daily oral dosing. Change from baseline of peripheral blood mononuclear cell (PBMC) glycogen, which correlated with muscle glycogen levels in preclinical models, was significantly reduced dose-dependently following 10 days of MZE001 treatment in healthy subjects. A muscle biopsy sub-study demonstrated that 10 days of MZE001 (480 mg BID) dosing safely and substantially lowered muscle glycogen stores in healthy adults. This correlated with the PBMC exposure response and supports the use of PBMC glycogen reduction as a surrogate for muscle response, and MZE001 potential for development as the first oral substrate reduction therapy for patients with Pompe disease.

Glycogenesis and glyconeogenesis from glutamine, lactate and glycerol support human macrophage functions.

Macrophages fight infection and ensure tissue repair, often operating at nutrient-poor wound sites. We investigated the ability of human macrophages to metabolize glycogen. We observed that the cytokines GM-CSF and M-CSF plus IL-4 induced glycogenesis and the accumulation of glycogen by monocyte-derived macrophages. Glyconeogenesis occurs in cells cultured in the presence of the inflammatory cytokines GM-CSF and IFNγ (M1 cells), via phosphoenolpyruvate carboxykinase 2 (PCK2) and fructose-1,6-bisphosphatase 1 (FBP1). Enzyme inhibition with drugs or gene silencing techniques and 13C-tracing demonstrate that glutamine (metabolized by the TCA cycle), lactic acid, and glycerol were substrates of glyconeogenesis only in M1 cells. Tumor-associated macrophages (TAMs) also store glycogen and can perform glyconeogenesis. Finally, macrophage glycogenolysis and the pentose phosphate pathway (PPP) support cytokine secretion and phagocytosis regardless of the availability of extracellular glucose. Thus, glycogen metabolism supports the functions of human M1 and M2 cells, with inflammatory M1 cells displaying a possible dependence on glyconeogenesis.

Knockdown of Ketohexokinase Versus Inhibition of Its Kinase Activity Exert Divergent Effects on Fructose Metabolism.

Excessive fructose intake is a risk factor for the development of obesity and its complications. Targeting ketohexokinase (KHK), the first enzyme of fructose metabolism, has been investigated for the management of MASLD. We compared the effects of systemic, small molecule inhibitor of KHK enzymatic activity to hepatocyte-specific, GalNAc-siRNA mediated knockdown of KHK in mice on a HFD. We measured KHK enzymatic activity, extensively quantified glycogen accumulation, performed RNAseq analysis, and enumerated hepatic metabolites using mass spectrometry. Both KHK siRNA and KHK inhibitor led to an improvement in liver steatosis, however, via substantially different mechanisms. KHK knockdown decreased the de novo lipogenesis pathway, whereas the inhibitor increased the fatty acid oxidation pathway. Moreover, KHK knockdown completely prevented hepatic fructolysis and improved glucose tolerance. Conversely, the KHK inhibitor only partially reduced fructolysis, but it also targeted triokinase, mediating the third step of fructolysis. This leads to the accumulation of fructose-1 phosphate, resulting in glycogen accumulation, hepatomegaly, and impaired glucose tolerance. Overexpression of wild-type, but not kinase-dead KHK in cultured hepatocytes increased hepatocyte injury and glycogen accumulation when treated with fructose. The differences between KHK inhibition and knockdown are, in part, explained by the kinase-dependent and independent effects of KHK on hepatic metabolism.

MRNA-seq-based analysis predicts: AEG-1 is a therapeutic target and immunotherapy biomarker for pan-cancer, including OSCC.

The aberrant expression of AEG-1 is significantly correlated with tumorigenesis, development, neurodegeneration and inflammation. However, the relationship between AEG-1 expression and immune infiltration in OSCC, as well as other tumor types, has yet to be comprehensively analyzed. The expression levels, prognostic and clinicopathological characteristics, mutation patterns and methylation landscapes of AEG-1 in various tumors were obtained from multiple databases, including TIMER, GEPIA, HPA, TCGA, UALCAN, cBioPortal, SMART and TISIDB, in addition to single-cell RNA-seq data. The integration of these datasets facilitated the elucidation of the relationships among pan-cancer cellular heterogeneity, immune infiltration and AEG-1 expression levels. In vitro experiments created AEG-1 overexpressing cell lines, and mRNA-seq analyzed AEG-1-related differential genes in OSCC. RT-PCR validated these findings in vivo using xenograft tumors. Tumor cell lines were developed to study AEG-1's effects through H&E, Masson, and PAS staining. Immunohistochemistry examined AEG-1-related gene expression patterns. Our analysis demonstrated that AEG-1 is highly expressed across various cancer types and is associated with tumor grade and patient prognosis. Additionally, AEG-1 amplification was observed in multiple cancers. Notably, we identified a significant elevation of AEG-1 expression in OSCC, which strongly correlated with patient prognosis and immune infiltration. Through mRNA-seq analysis of differentially expressed genes and immune-related gene sets, we identified a strong correlation between AEG-1 and immune infiltration markers such as LCP2, CD247, HLA-DPA1, HLA-DRA, HLA-DRB1, CIITA and CD74 in OSCC. Additionally, AEG-1 was found to regulate Th1/Th2 immune homeostasis, promote glycogen accumulation, and contribute to tumor fibrosis. In conclusion, AEG-1 significantly correlates with prognosis and immune infiltration across various cancer types and holds potential as a novel prognostic immune biomarker for OSCC. This finding may facilitate the identification of patients who are most likely to benefit from adjuvant immunotherapy.

Gluconeogenesis and glycogenolysis required in metastatic breast cancer cells.

Metabolic adaptability, including glucose metabolism, enables cells to survive multiple stressful environments. Glycogen may serve as a critical storage depot to provide a source of glucose during times of metabolic demand during the metastatic cascade; therefore, understanding glycogen metabolism is critical. Our goal was to determine mechanisms driving glycogen accumulation and its role in metastatic (MCF10CA1a) compared to nonmetastatic (MCF10A-ras) human breast cancer cells. 13C6-glucose flux analysis in combination with inhibitors of the gluconeogenic pathway via phosphoenolpyruvate carboxykinase (PCK), the anaplerotic enzyme pyruvate carboxylase (PC), and the rate-limiting enzyme of the pentose phosphate pathway (PPP) glucose 6-phosphate dehydrogenase (G6PD). To determine the requirement of glycogenolysis for migration or survival in extracellular matrix (ECM) detached conditions, siRNA inhibition of glycogenolysis (liver glycogen phosphorylase, PYGL) or glycophagy (lysosomal enzyme α-acid glucosidase, GAA) enzymes was utilized. Metastatic MCF10CA1a cells had 20-fold greater glycogen levels compared to non-metastatic MCF10A-ras cells. Most glucose incorporated into glycogen of the MCF10CA1a cells was in the five 13C-containing glucose (M+5) instead of the expected M+6 glycogen-derived glucose moiety, which occurs through direct glucose conversion to glycogen. Furthermore, 13C6-glucose in glycogen was quickly reduced (~50%) following removal of 13C-glucose. Incorporation of 13C6-glucose into the M+5 glucose in the glycogen stores was reduced by inhibition of PCK, with additional contributions from flux through the PPP. Further, inhibition of PC reduced total glycogen content. However, PCK inhibition increased total unlabeled glucose accumulation into glycogen, suggesting an alternative pathway to glycogen accumulation. Inhibition of the rate-limiting steps in glycogenolysis (PYGL) or glycophagy (GAA) demonstrated that both enzymes are necessary to support MCF10CA1a, but not MCF10A-ras, cell migration. GAA inhibition, but not PYGL, reduced viability of MCF10CA1a cells, but not MCF10A-ras, in ECM detached conditions. Our results indicate that increased glycogen accumulation is primarily mediated through the gluconeogenesis pathway and that glycogen utilization is required for both migration and ECM detached survival of metastatic MCF10CA1a cells. These results suggest that glycogen metabolism may play an important role in the progression of breast cancer metastasis.

In vivo mapping of postprandial hepatic glucose metabolism using dynamic magnetic resonance spectroscopy combined with stable isotope flux analysis in Roux-en-Y gastric bypass adults and non-operated controls: A case-control study.

Roux-en-Y gastric bypass (RYGB) surgery alters postprandial glucose profiles, causing post-bariatric hypoglycaemia (PBH) in some individuals. Due to the liver's central role in glucose homeostasis, hepatic glucose handling might differ in RYGB-operated patients with PBH compared to non-operated healthy controls (HC). We enrolled RYGB-operated adults with PBH and HCs (n = 10 each). Participants ingested 60 g of [6,6'-2H2]-glucose (d-glucose) after an overnight fast. Deuterium metabolic imaging (DMI) with interleaved 13C magnetic resonance spectroscopy was performed before and until 150 min post-d-glucose intake, with frequent blood sampling to quantify glucose enrichment and gluco-regulatory hormones until 180 min. Glucose fluxes were assessed by mathematical modelling. Outcome trajectories were described using generalized additive models. In RYGB subjects, the hepatic d-glucose signal increased early, followed by a decrease, whereas HCs exhibited a gradual increase and consecutive stabilization. Postprandial hepatic glycogen accumulation and the suppression of endogenous glucose production were lower in RYGB patients than in HCs, despite higher insulin exposure, indicating lower hepatic insulin sensitivity. The systemic rate of ingested d-glucose was faster in RYGB, leading to a higher, earlier plasma glucose peak and increased insulin secretion. Postprandial glucose disposal increased in RYGB patients, without between-group differences in peripheral insulin sensitivity. Exploiting DMI with stable isotope flux analysis, we observed distinct postprandial hepatic glucose trajectories and parameters of glucose-insulin homeostasis in RYGB patients with PBH versus HCs. Despite altered postprandial glucose kinetics and higher insulin exposure, there was no evidence of impaired hepatic glucose uptake or output predisposing to PBH in RYGB patients.

3D Bioprinting of Pig Macrophages and Human Cells Discovered the P2Y14 Receptor as a Mediator of Xenogenic Immune Responses

ABSTRACT Background The survival rate of pig lung xenotransplantation (PLXTx) recipients is severely limited by intense xenogenic immune responses, necessitating further insights into xenogeneic immunity and the development of models to study the PLXTx immune response. Methods We identified regulators of PLXTx immune response Using Gene ontology analysis. We assessed the metabolic changes and protein levels in 3D4/31 pig alveolar macrophages (PAMs) through flow cytometry and immunoblotting. To induce a xenogenic immune response, we co-cultured 3D4/31-PAMs with A549 human alveolar epithelial cells and evaluated cytokine expression using qRT-PCR. Results Gene ontology analysis identified STAT1 and alveolar macrophages as contributors to lung autoimmunity and transplant rejection. In 3D4/31-PAMs, phorbol myristate acetate-induced glycogen accumulation and cyclooxygenase-2 expression were inhibited by the P2Y14 inhibitor PPTN. Co-culturing 3D4/31-PAMs with A549 human alveolar epithelial cells via 3D bioprinting resulted in a more pronounced inflammatory response than 2D co-culture, with increased expression of genes related to the P2Y14 cascade and inflammation. This inflammatory gene expression was prevented by PPTN treatment. Conclusion Based on these results, we propose alginate bioprinting as an in vitro model for PLXTx and suggest that P2Y14 is a key regulator of xenogeneic immune responses in PAMs.

Vitamin D3 mitigates myopathy and metabolic dysfunction in rats with metabolic syndrome: the potential role of dipeptidyl peptidase-4.

Metabolic syndrome is associated with vitamin D3 deficiency. This work aims to examine the efficacy of vitamin D3 in inhibiting MetS-induced myopathy and to determine whether the beneficial effects of vitamin D3 are mediated by the inhibition of dipeptidyl peptidase-4 (DPP-4). An in silico study investigated the potential effectiveness of vitamin D3 on the inhibition of the DPP-4 enzyme. An in vitro assay of the DPP-4 inhibitory effect of vitamin D3 was performed. In vivo and over 12 weeks, both diet (with 3% salt) and drinking water (with 10% fructose) were utilized to induce MetS. In the seventh week, rats received either vitamin D3, vildagliptin, a combination of both, or vehicles. Serum lipids, adipokines, glycemic indices, and glucagon-like peptide-1 (GLP-1), muscular glucose transporter type-4 (GLUT-4) content, DPP-4, adenosine monophosphate kinase (AMPK) activities, and Sudan Black B-stained lipids were assessed. Muscular reactive oxygen species (ROS), caspase-3, and desmin immunostaining were used to determine myopathy. MetS-induced metabolic dysfunction was ameliorated by vitamin D3, which also reduced intramuscular glycogen and lipid accumulation. This is demonstrated by the attenuation of MetS-induced myopathy by vitamin D3, decreased oxidative stress, increased desmin immuno-expression, and caspase-3 activity. Our in silico data demonstrated that vitamin D3 is capable of inhibiting DPP-4, which is further supported by biochemical findings. Vitamin D3 increased serum GLP-1, muscular AMPK activity, and GLUT-4 content, whereas the levels of muscular ROS were decreased in MetS. Vildagliptin and its combination with vitamin D3 yielded comparable results. It is suggested that the DPP-4 inhibitory potential of vitamin D3 is responsible for the amelioration of MetS-induced metabolic changes and myopathy.

Cold Exposure Alleviates T2DM Through Plasma-Derived Extracellular Vesicles.

Anecdotal reports have praised the benefits of cold exposure, exemplified by activities like winter swimming and cold water immersion. Cold exposure has garnered acclaim for its potential to confer benefits and potentially alleviate diabetes. We posited that systemic cold temperature (CT, 4-8°C) likely influences the organism's blood components through ambient temperature, prompting our investigation into the effects of chronic cold exposure on type 2 diabetic (T2DM) mice and our initial exploration of how cold exposure mitigates the incidence of T2DM. The effects of CT (4-8°C) or room temperature (RT, 22-25°C) on T2DM mice were investigated. Mice blood and organ specimens were collected for fully automated biochemical testing, ELISA, HE staining, immunohistochemistry, and immunofluorescence. Glucose uptake was assessed using flow cytometry with 2-NBDG. Changes in potential signaling pathways such as protein kinase B (AKT), phosphorylated AKT (p-AKT), insulin receptor substrates 1 (IRS1), and phosphorylated IRS1 (p-IRS1) were evaluated by Western blot. CT or CT mice plasma-derived extracellular vesicles (CT-EVs) remarkably reduced blood glucose levels and improved insulin sensitivity in T2DM mice. This treatment enhanced glucose metabolism, systemic insulin sensitivity, and insulin secretion function while promoting glycogen accumulation in the liver and muscle. Additionally, CT-EVs treatment protected against the streptozocin (STZ)-induced destruction of islets in T2DM mice by inhibiting β-cell apoptosis. CT-EVs also shielded islets from destruction and increased the expression of p-IRS1 and p-AKT in adipocytes and hepatocytes. In vitro experiments further confirmed its pro-insulin sensitivity effect. Our data indicate that cold exposure may have a potentially beneficial effect on the development of T2DM, mainly through the anti-diabetic effect of plasma-derived EVs released during cold stimulation. This phenomenon could significantly contribute to understanding the lower prevalence of diabetes in colder regions.

First person – Monica Shukla

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Disease Models &amp; Mechanisms, helping researchers promote themselves alongside their papers. Monica Shukla is first author on ‘ Neuromuscular junction dysfunction in Lafora disease’, published in DMM. Monica is a PhD scholar in the lab of Professor S. Ganesh at the Indian Institute of Technology, Kanpur, India, investigating the influence of aberrant glycogen accumulation in neurodegenerative disorders, emphasising its effects on both the brain and muscles, and exploring how mitigating glycogen levels could alleviate the associated disease phenotype.

Time and dose selective glucose metabolism for glucose homeostasis and energy conversion in the liver.

Hepatic glucose metabolism serves dual purposes: maintaining glucose homeostasis and converting glucose into energy sources; however, the underlying mechanisms are unclear. We quantitatively measured liver metabolites, gene expression, and phosphorylated insulin signaling molecules in mice orally administered varying doses of glucose, and constructed a transomic network. Rapid phosphorylation of insulin signaling molecules in response to glucose intake was observed, in contrast to the more gradual changes in gene expression. Glycolytic and gluconeogenic metabolites and expression of genes involved in glucose metabolism including glucose-6-phosphate, G6pc, and Pck1, demonstrated high glucose dose sensitivity. Whereas, glucokinase expression and glycogen accumulation showed low glucose dose sensitivity. During the early phase after glucose intake, metabolic flux was geared towards glucose homeostasis regardless of the glucose dose but shifted towards energy conversion during the late phase at higher glucose doses. Our research provides a comprehensive view of time- and dose-dependent selective glucose metabolism.

Dang-Gui-Bu-Xue decoction against diabetic nephropathy via modulating the carbonyl compounds metabolic profile and AGEs/RAGE pathway

BackgroundDang-Gui-Bu-Xue decoction (DBD) is a traditional Chinese medicine prescription clinically employed for diabetic nephropathy (DN). However, the components and pharmacological mechanisms of DBD against DN remain incompletely understood. PurposeTo clarify the beneficial effect of DBD on DN and to explore its nephroprotective effect's probable mechanism and the main components. MethodsA diabetic mice model was established by feeding a high-fat diet (HFD) and intraperitoneal injections of streptozotocin (STZ, 40 mg‧kg-1). Subsequently, the mice were maintained on a HFD and administered with DBD. The benefits of DBD against DN were comprehensively assessed by monitoring energy and water intake, blood glucose and lipids, renal functions and pathological status. The UPLC-MS/MS was measured to detect chemical constituents in DBD and absorbed components in DBD-treated plasma under physiological and pathological states. Network pharmacology was employed to forecast the probable pathways of DBD intervention in DN, with subsequent validation of these predictions through testing biochemical parameters, anti-glycation and ELISA assays, immunofluorescence, immunohistochemistry, and western blotting. Then, a chemical derivatization method paired with UPLC-MS/MS analysis was performed to detect the carbonyl compounds in renal tissue. Finally, the main components of DBD against DN were screened by anti-glycation and MTT assays. ResultsDBD regulated energy and water intakes, glucose and lipid metabolism disorders, renal dysfunction, glomerular filtration rate, renal interstitial glycogen accumulation and fibrosis in HFD/STZ-induced DN mice. A total of 129 distinct chemical constituents in DBD were characterized, of which 28 were detected in the DBD-treated plasma under a pathological state. The network pharmacological results suggested AGEs/RAGE and its downstream pathway may be a potential pathway for DBD intervention in DN. Further experiments confirmed that DBD reduced renal oxidative stress by modulating the AGEs/RAGE pathway. Moreover, 21 differential carbonyl compounds were detected between normal and DN mice, and DBD significantly modulated 16. Ultimately, seven components were screened out in DBD, which may be the main components of DBD regulating carbonyl compounds metabolic profile and AGEs/RAGE pathway. ConclusionOur findings suggested for the first time that DBD could regulate the carbonyl compounds metabolic profile and AGEs/RAGE signaling pathway to ameliorate DN.

Chondroitin Sulfate from Halaelurus burgeri Skin Inhibits Hepatic Endoplasmic Reticulum Stress and Inflammation, and Regulates Gut Microbiota.

Previous study has demonstrated the chemical structure of chondroitin sulfate (CHS) from Halaelurus burgeri skin and its effects on insulin resistance. However, the precise impact of this phenomenon on endoplasmic reticulum (ER) stress and inflammation, which contribute to insulin resistance, remains unclear. This study is to investigate the impact of CHS on ER stress, inflammatory response and signaling, and gut microbiota in high-fat diet (HFD)-fed mice. HFD-fed C57BL/6J mice receive dietary gavage intervention of CHS for 18 weeks. Blood, liver tissue, and feces are harvested for further investigation. Results show that CHS inhibits ER stress, accompanied by lowered blood glucose, nitric oxide (NO), reactive oxygen (ROS), and free fatty acids (FFA) levels, and increases hepatic glycogen accumulation. Moreover, hepatic inflammation is improved by CHS treatment via inactivation of Toll-like receptor 4 (TLR4) signaling and its downstream c-jun N-terminal kinase (JNK) and nuclear factor kappa B (NFκB) pathways. Additionally, CHS regulates gut microbiota, particularly the decline in the Firmicutes to Bacteroidetes ratio. CHS also lowers fecal lipopolysaccharide and elevates several fecal short chain fatty acids. These findings suggest that CHS from H. burgeri skin may be an alternative functional food supplement for anti-ER stress, anti-inflammtion, and regulation of gut microbiota.

Glycogen synthase activity in Candida albicans is partly controlled by the functional ortholog of Saccharomyces cerevisiae Gac1p.

To adapt to various host microenvironments, the human fungal pathogen Candida albicans possesses the capacity to accumulate and store glycogen as an internal carbohydrate source. In the model yeast Saccharomyces cerevisiae, ScGlc7p and ScGac1p are the serine/threonine type 1 protein phosphatase catalytic and regulatory subunits that control glycogen synthesis by altering the phosphorylation state of the glycogen synthase Gsy2p. Despite recent delineation of the glycogen synthesis pathway in C. albicans, the molecular events driving synthase activation are currently undefined. In this study, using a combination of microbiologic and genetic techniques, we determined that the protein encoded by uncharacterized gene C1_01140C, and not the currently annotated C. albicans Gac1p, is the major regulatory subunit involved in glycogen synthesis. C1_01140Cp contains a conserved GVNK motif observed across multiple starch/glycogen-binding proteins in various species, and alanine substitution of each residue in this motif significantly impaired glycogen accumulation in C. albicans. Fluorescent protein tagging and microscopy indicated that C1_01140Cp-GFPy colocalized with CaGlc7p-tdTomato and CaGsy1p-tdTomato accordingly. Co-immunoprecipitation assays further confirmed that C1_01140Cp associates with CaGlc7p and CaGsy1p during glycogen synthesis. Lastly, c1_01140cΔ/Δ exhibited colonization defects in a murine model of vulvovaginal candidiasis. Collectively, our data indicate that uncharacterized C1_01140Cp is the functional ortholog of the PPP1R subunit ScGac1p in C. albicans.IMPORTANCEThe capacity to synthesize glycogen offers microbes metabolic flexibility, including the fungal pathogen Candida albicans. In Saccharomyces cerevisiae, dephosphorylation of glycogen synthase by the ScGlc7p-containing phosphatase is a critical rate-limiting step in glycogen synthesis. Subunits, including ScGac1p, target ScGlc7p to α-1,4-glucosyl primers for efficient ScGsy2p synthase activation. However, this process in C. albicans had not been delineated. Here, we show that the C. albicans genome encodes for two homologous phosphatase-binding subunits, annotated CaGac1p and uncharacterized C1_01140Cp, both containing a GVNK motif required for polysaccharide affinity. Surprisingly, loss of CaGac1p only moderately reduced glycogen accumulation, whereas loss of C1_01140Cp ablated it. Fluorescence microscopy and co-immunoprecipitation approaches revealed that C1_01140Cp associates with CaGlc7p and CaGsy1p during glycogen synthesis. Moreover, C1_01140Cp contributed to fungal fitness at the vaginal mucosa during murine vaginitis. Therefore, this work demonstrates that glycogen synthase regulation is conserved in C. albicans and C1_01140Cp is the functional ortholog of ScGac1p.