Search Results (35)

Background: The most common form of monogenic diabetes is maturity onset diabetes of the young (MODY). This study investigates the molecular basis of MODY type 2 (GCK-MODY) in a group of Italian patients, focusing on the functional characterization of a synonymous variant, c.579G>T (p.Gly193Gly), in the glucokinase gene (GCK). Methods: Clinical evaluation and genetic analysis, including whole exome sequencing and Sanger sequencing, were used to identify the variant in GCK, then functional studies using a minigene approach allowed the functional characterization. Results: This study identified the synonymous variant, along with a nonsense mutation, c.859C>T (p.Gln287Ter), in GCK in two Italian patients. Minigene approach demonstrated that the synonymous variant disrupts splicing at the exon 5 boundary, leading to a frameshift and premature stop codon. Similarly, the nonsense mutation also altered splicing, exacerbating the molecular defect. Conclusions: These findings highlight the importance of functional assays, particularly minigene studies, in interpreting the pathogenicity of synonymous and nonsense variants, especially in genes like GCK where splicing alterations can significantly impact protein function. This study underscores the clinical utility of targeted genetic screening for personalized diabetes management. Full article

Precision medicine starts with a precision diagnosis. Yet up to 80% of cases of monogenic diabetes, a form of diabetes characterized by mutations in a single gene, are either overlooked or misdiagnosed. A genetic test for monogenic diabetes does not always lead to a precise diagnosis, as novel variants are often classified as variants of unknown significance. Variant interpretation requires collation of a framework of evidence, including population, computational, and segregation data, and can be assisted by functional analysis. The inclusion of functional data can be challenging, depending on the number of benign and pathogenic variants available for benchmarking assays. Glucokinase is the rate-limiting step for glucose metabolism in the pancreatic beta-cell and governs the threshold for glucose-stimulated insulin release. Loss-of-function alleles in the glucokinase (GCK) gene are a cause of stable fasting hyperglycemia from birth and/or diabetes. In this study, we functionally characterized 25 variants identified during diagnostic testing or in exome sequencing studies. We assessed their kinetic characteristics, stability, and interaction with pharmacological and physiological regulators. We integrated our functional data with existing data from the ClinGen Monogenic Diabetes Variant Curation Expert Review panel using a gene-specific framework to assist variant classification. We show how functional evidence can aid variant classification, thus enabling diagnostic certainty. Full article

Background/Objectives: Compartmentalized glucose metabolism in the brain contributes to neuro-metabolic stability and shapes hypothalamic control of glucose homeostasis. Glucose transporter-2 (GLUT2) is a plasma membrane glucose sensor that exerts sex-specific control of hypothalamic astrocyte glucose and glycogen metabolism. Aging causes counterregulatory dysfunction. Methods: The current research used Western blot and HPLC–electrospray ionization–mass spectrometry to investigate whether aging affects the GLUT2-dependent hypothalamic astrocyte metabolic sensor, glycogen enzyme protein expression, and glycogen mass according to sex. Results: The data document GLUT2-dependent upregulated glucokinase (GCK) protein in glucose-deprived old male and female astrocyte cultures, unlike GLUT2 inhibition of this protein in young astrocytes. Glucoprivation of old male and female astrocytes caused GLUT2-independent downregulation of 5′-AMP-activated protein kinase (AMPK) protein, indicating loss of GLUT2 stimulation of this protein with age. This metabolic stress also caused GLUT2-dependent suppression of phospho-AMPK profiles in each sex, differing from GLUT2-mediated glucoprivic enhancement of activated AMPK in young male astrocytes and phospho-AMPK insensitivity to glucoprivation in young female cultures. GS and GP isoform proteins were refractory to glucoprivation of old male cultures, contrary to downregulation of these proteins in young glucose-deprived male astrocytes. Aging elicited a shift from GLUT2 inhibition to stimulation of male astrocyte glycogen accumulation and caused gain of GLUT2 control of female astrocyte glycogen. Conclusions: The outcomes document sex-specific, aging-related alterations in GLUT2 control of hypothalamic astrocyte glucose and ATP monitoring and glycogen mass and metabolism. These results warrant future initiatives to assess how these adjustments in hypothalamic astrocyte function may affect neural operations that are shaped by astrocyte–neuron metabolic partnership. Full article

As next-generation sequencing develops, there are significant associations between glucokinase regulatory protein (GCKR) variants and many diseases, especially metabolic diseases. However, there is a lack of solid descriptions and summaries of how GCKR variants lead to diseases and a lack of successful translations of drugs targeting this molecular variant. We searched literature datasets, mainly including PubMed and Web of Science, with “GCKR” or “GKRP”, “Variants”, “Hypertriglyceridemia”, “NAFLD”, and “Metabolic diseases” as the search terms. Our review firstly introduces the biological function of the GCKR gene and its encoding protein GKRP and then describes the GCKR variants in different diseases, such as hypertriglyceridemia and NAFLD, revealing that GCKR/GKPR is strongly associated with metabolic diseases. GKPR might be a potential target for T2D and other metabolic diseases. One drug for interfering with the GCK-GKRP complex has been developed and has shown its effectiveness in preclinical studies, with some possible side effects. More and more different-structured drugs should be developed to improve side effects, and more clinical trials should be carried out to determine the best intervention window and timing points to improve prognosis. Taken together, these insights show that GCKR/GKRP is significantly associated with many metabolic diseases via its complex metabolism system and is a potential target in many metabolic diseases. Full article

Background: Dietary consumption of insulinogenic amino acids (IAA) is known to contribute to the development of insulin resistance. It remains to be studied whether dietary IAA restriction improves glucose metabolism and insulin sensitivity and whether this improvement is related to alterations in glucose metabolism in peripheral tissues. The objective of this study was to examine the effect of IAA restriction on glucose metabolism in a piglet model. Methods: Following the acclimation period, thirty-two seven-day-old male piglets were randomly assigned into one of three groups for three weeks as follows (n = 10–11/group): (1) NR (control): basal diet without IAA restriction; (2) R50: basal diet with IAA restricted by 50%; (3) R75: basal diet with IAA restricted by 75%. IAA were alanine (Ala), arginine (Arg), isoleucine (Ile), leucine (Leu), lysine (Lys), threonine (Thr), phenylalanine (Phe), and valine (Val) as suggested by previous studies. Thermal images, body weight, and growth parameters were recorded weekly, oral glucose tolerance tests were performed on week 2 of the study, and blood and tissue samples were collected on week 3 after a meal test. Results: R75 improved glucose tolerance and, together with R50, reduced blood insulin concentration and homeostatic model assessment for insulin resistance (HOMA-IR) value, which is suggestive of improved insulin sensitivity following IAA restriction. R75 increased thermal radiation and decreased adipocyte number in white adipose tissue (WAT). R75 had a greater transcript of glucose transporter 1 (GLUT1), phosphofructokinase, liver type (PFKL), and pyruvate kinase, liver, and RBC (PKLR) in the liver and glucokinase (GCK) in WAT indicating a higher uptake of glucose in the liver and greater glycolysis in both liver and WAT. R75 increased the mRNA abundance of insulin receptor substrate 1 (IRS1) and protein kinase B (AKT1) in skeletal muscle suggestive of enhanced insulin signaling. Further, R75 had a higher mRNA of fibroblast growth factor 21 (FGF-21) in both the liver and hypothalamus and its upstream molecules such as activating transcription factor 4 (ATF4) and inhibin subunit beta E (INHBE) which may contribute to increased energy expenditure and improved glucose tolerance during IAA restriction. Conclusions: IAA restriction improves glucose tolerance and insulin sensitivity in piglets while not reducing body weight, likely through improved hepatic glycolysis and insulin signaling in skeletal muscle, and induced FGF-21 signaling in both the liver and hypothalamus. Full article

Type 2 diabetes (T2D) is a prevalent chronic disease in the Korean population, influenced by lifestyle, dietary habits, and genetics. This study aimed to identify the effects of food intake and genetic factors on T2D progression in Korean adults using a multi-state illness-death model. We analyzed three transition models: normal glucose tolerance (NGT) to prediabetes (PD), NGT to T2D, and PD to T2D. We first identified dietary patterns significantly associated with each transition, using multivariate Cox proportional hazards models. Then, we assessed the impact of single-nucleotide polymorphisms (SNPs) on each transition, incorporating these dietary patterns as covariates. Our analysis revealed significant associations between the identified dietary patterns and the risk of PD and T2D incidence among individuals with NGT. We also identified novel genetic variants associated with disease progression: two SNPs (rs4607517 in Glucokinase [GCK] and rs758982 in Calcium/Calmodulin-Dependent Protein Kinase II Beta [CAMK2B]) in the NGT to PD model, and eight SNPs in the NGT to T2D model, including variants in the Zinc Finger Protein 106 (ZNF106), PTOV1 Extended AT-Hook Containing Adaptor Protein (PTOV1), Proprotein Convertase Subtilisin/Kexin Type 2 (PCSK2), Forkhead Box D2 (FOXD2), Solute Carrier Family 38 Member 7 (SLC38A7), and Neuronal Growth Regulator 1 (NEGR1) genes. Functional annotation analysis using ANNOVAR revealed that rs4607517 (GCK) and rs59595912 (PTOV1) exhibited high Combined Annotation-Dependent Depletion (CADD) and Deleterious Annotation of Genetic Variants using Neural Networks (DANN) scores, suggesting potential pathogenicity and providing a functional basis for their association with T2D progression. Integrating dietary and genetic factors with a multi-state model, this comprehensive approach offers valuable insights into T2D development and highlights potential targets for prevention and personalized interventions. Full article

Background/Objectives: Our lab has previously reported that Grifola frondosa (maitake mushroom) GF5000 has antidiabetic potential owing to its ability to improve insulin resistance. This study aimed to gain insight into the system-level hypoglycemic mechanisms of GF5000 using transcriptomics, proteomics, and network pharmacology. This study provides new insights into the hypoglycemic mechanisms of GF5000, identifying key molecular targets involved in mitigating insulin resistance in T2DM. Methods: Liver protein and gene expression in normal control (NC), diabetic control (DC), and GF5000-treated (GF5000) rats were analyzed via iTRAQ and RNA-seq. The relationships between differentially expressed genes (DEGs), differentially expressed proteins (DEPs), and type 2 diabetes (T2DM) disease targets were studied using Metascape and the Cytoscape GeneMANIA plug-in. Results: One hundred and fifty-two DEGs and sixty-two DEPs were identified; twenty DEGs/DEPs exhibited the same trend in mRNA and protein expression levels when comparing the GF5000 vs. DC groups. The Metascape analysis revealed that the T2DM disease targets included four DEGs—Gck, Scd, Abcb4, and Cyp3a9—and two DEPs—glucokinase and acetyl-CoA carboxylase 2. A Cytoscape–GeneMANIA analysis of thirteen DEGs/DEPs related to T2DM showed that Apoa1/Apolipoprotein A-I, Gckr/glucokinase regulatory protein, and Gck/glucokinase had the highest connectivity and centrality in the topological network. The qPCR results confirmed that GF5000 increased the mRNA expression of GCK in GCK-knockdown HepG2 cells. Conclusions: These results provide theoretical evidence for the use of GF5000 as a potential active nutritional ingredient for the prevention and treatment of T2DM. Our findings suggest that GF5000 targets multiple pathways implicated in T2DM, offering a multi-faceted approach to disease management and prevention. Full article

Analyzing the genetic architecture of hereditary forms of diabetes in different populations is a critical step toward optimizing diagnostic and preventive algorithms. This requires consideration of regional and population-specific characteristics, including the spectrum and frequency of pathogenic variants in targeted genes. As part of this study, we used a custom-designed NGS panel to screen for mutations in 28 genes associated with the pathogenesis of hereditary diabetes mellitus in 506 unrelated patients from Russia. The study identified 180 pathogenic or likely pathogenic variants across 13 genes (GCK, HNF1A, HNF1B, HNF4A, ABCC8, INS, INSR, KCNJ11, PAX4, PDX1, ZFP57, BLK, WFS1), representing 46.44% of the analyzed cohort (235 individuals). The glucokinase gene (GCK) had the highest number of identified variants, with 111 variants detected in 161 patients, 20 of which were identified for the first time. In the tissue-specific transcription factor genes HNF1A, HNF4A, and HNF1B, 34 variants were found in 38 patients, including 13 that were previously unreported. Seventeen variants were identified in the ABCC8 gene, which encodes the ATP-binding cassette transporter 8 of subfamily C, each found in a different patient; four of these were novel discoveries. Nine pathogenic or likely pathogenic variants were identified in the insulin gene (INS) and its receptor gene (INSR), including four previously unreported variants. Additionally, we identified 10 previously unreported variants in six other genes among 11 patients. Variants in the genes GCK, HNF1A, HNF1B, HNF4A, ABCC8, INS, and INSR were the main contributors to the genetic pathogenesis of hereditary diabetes mellitus in the Russian cohort. These findings enhance our understanding of the molecular mechanisms underlying the disease and provide a solid basis for future studies aimed at improving diagnostic accuracy and advancing personalized therapeutic strategies. This knowledge provides a foundation for developing region-specific genetic testing algorithms and personalized therapeutic strategies, which are critical for future initiatives in precision medicine. Full article

Dark tea has great potential in regulating glycolipid metabolism, and theabrownin (TB) is considered to be the characteristic and bioactive constituent of dark tea. This study evaluated the ability of TB1 (fermented for 7 days) and TB2 (fermented for 14 days) isolated from dark tea to reverse insulin resistance (IR) in HepG2 cells. The results indicated that TB significantly ameliorated oxidative stress by improving mitochondrial function. In addition, TB improved glycogen synthesis and glucose consumption, and inhibited gluconeogenesis and fatty acid synthesis, by regulating GSK3β (Glycogen synthase kinase 3β), G6Pase (Glucose-6-phosphatase), GCK (Glucokinase), PEPCK1 (Phosphoenolpyruvate carboxy kinase 1), SREBP-1C (sterol regulatory element-binding protein 1C), FASN (fatty acid synthase), and ACC (Acetyl-CoA carboxylase). Additionally, the results of Western blot and real-time PCR experiments demonstrated that TB modulated glucolipid metabolism through the IRS-1 (Insulin receptor substrate 1)/PI3K (phosphatidylinositol-3 kinase)/Akt (protein kinase B) signaling pathway. Treatment with the PI3K inhibitor demonstrated a favorable correlation between PI3K activation and TB action on glycolipid metabolism. Notably, we observed that TB2 had a greater effect on improving insulin resistance compared with TB1, which, due to its prolonged fermentation time, increased the degree of oxidative polymerization of TB. Full article

The aim of this study was to investigate the disruptions of metabolic pathways induced by bisphenol A (BPA) and explore the potential therapeutic intervention provided by resveratrol (RSV) in mitigating these disruptions through the modulation of biochemical pathways. Wistar albino rats were divided into three groups: group 1 served as the control, group 2 received 70 mg/Kg of BPA, and group 3 received 70 mg/kg of BPA along with 100 mg/Kg of RSV. After the treatment period, various biomarkers and gene expressions were measured to assess the effects of BPA and the potential protective effects of RSV. The results revealed that BPA exposure significantly increased the serum levels of α-amylase, α-glucosidase, G6PC, insulin, HbA1c, HMG-CoA reductase, FFAs, TGs, DPP-4, MDA, and proinflammatory cytokines such as TNF-α and IL-6. Concurrently, BPA exposure led to a reduction in the levels of antioxidant enzymes such as catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD), as well as GLUT4 and HDL cholesterol. However, the administration of RSV along with BPA significantly ameliorated these alterations in the biomarker levels induced through BPA exposure. RSV treatment effectively reduced the elevated levels of α-amylase, α-glucosidase, G6PC, insulin, HbA1c, HMG-CoA reductase, FFAs, TGs, DPP-4, MDA, and proinflammatory cytokines, while increasing the levels of antioxidant enzymes, GLUT4, and HDL cholesterol. Furthermore, BPA exposure suppressed the mRNA expression of glucokinase (GCK), insulin-like growth factor 1 (IGF-1), and glucose transporter 2 (GLUT2) and up-regulated the mRNA expression of uncoupling protein 2 (UCP2), which are all critical biomarkers involved in glucose metabolism and insulin regulation. In contrast, RSV treatment effectively restored the altered mRNA expressions of these biomarkers, indicating its potential to modulate transcriptional pathways and restore normal metabolic function. In conclusion, the findings of this study strongly suggest that RSV holds promise as a therapeutic intervention for BPA-induced metabolic disorders. By mitigating the disruptions in various metabolic pathways and modulating gene expressions related to glucose metabolism and insulin regulation, RSV shows potential in restoring normal metabolic function and counteracting the adverse effects induced by BPA exposure. However, further research is necessary to fully understand the underlying mechanisms and optimize the dosage and duration of RSV treatment for maximum therapeutic benefits. Full article

Hexokinases (HKs) convert hexose sugars to hexose-6-phosphate, thus trapping them inside cells to meet the synthetic and energetic demands. HKs participate in various standard and altered physiological processes, including cancer, primarily through the reprogramming of cellular metabolism. Four canonical HKs have been identified with different expression patterns across tissues. HKs 1–3 play a role in glucose utilization, whereas HK 4 (glucokinase, GCK) also acts as a glucose sensor. Recently, a novel fifth HK, hexokinase domain containing 1 (HKDC1), has been identified, which plays a role in whole-body glucose utilization and insulin sensitivity. Beyond the metabolic functions, HKDC1 is differentially expressed in many forms of human cancer. This review focuses on the role of HKs, particularly HKDC1, in metabolic reprogramming and cancer progression. Full article

Glucokinase-maturity onset diabetes of the young (GCK-MODY) is a kind of rare diabetes with low incidence of vascular complications caused by GCK gene inactivation. This study aimed to investigate the effects of GCK inactivation on hepatic lipid metabolism and inflammation, providing evidence for the cardioprotective mechanism in GCK-MODY. We enrolled GCK-MODY, type 1 and 2 diabetes patients to analyze their lipid profiles, and found that GCK-MODY individuals exhibited cardioprotective lipid profile with lower triacylglycerol and elevated HDL-c. To further explore the effects of GCK inactivation on hepatic lipid metabolism, GCK knockdown HepG2 and AML-12 cell models were established, and in vitro studies showed that GCK knockdown alleviated lipid accumulation and decreased the expression of inflammation-related genes under fatty acid treatment. Lipidomic analysis indicated that the partial inhibition of GCK altered the levels of several lipid species with decreased saturated fatty acids and glycerolipids including triacylglycerol and diacylglycerol, and increased phosphatidylcholine in HepG2 cells. The hepatic lipid metabolism altered by GCK inactivation was regulated by the enzymes involved in de novo lipogenesis, lipolysis, fatty acid β-oxidation and the Kennedy pathway. Finally, we concluded that partial inactivation of GCK exhibited beneficial effects in hepatic lipid metabolism and inflammation, which potentially underlies the protective lipid profile and low cardiovascular risks in GCK-MODY patients. Full article

Maturity Onset Diabetes of the Young (MODY) is a monogenic form of diabetes mellitus (DM) that accounts for around 2–5% of all types of diabetes. Autosomal dominant inheritance in pathogenic variations of 14 genes related to β-cell functions can lead to monogenic types of diabetes. In Italy, GCK/MODY is the most frequent form and it is caused by mutations of the glucokinase (GCK). Patients with GCK/MODY usually have stable mild fasting hyperglycaemia with mildly elevated HbA1c levels and rarely need pharmacological treatment. Molecular analysis of the GCK coding exons was carried out by Sanger sequencing in eight Italian patients. All the probands were found to be heterozygous carriers of a pathogenic gross insertion/deletion c.1279_1358delinsTTACA; p.Ser426_Ala454delinsLeuGln. It was previously described for the first time by our group in a large cohort of Italian GCK/MODY patients. The higher levels of HbA1c (6.57% vs. 6.1%), and the higher percentage of patients requiring insulin therapy (25% vs. 2%) compared to the previously studied Italian patients with GCK/MODY, suggest that the mutation discovered could be responsible for a clinically worse form of GCK/MODY. Moreover, as all the patients carrying this variant share an origin from the same geographic area (Liguria), we postulate a possible founder effect and we propose to name it the “pesto” mutation. Full article

This study aimed to investigate the effects of perfluorooctanesulfonic acid (PFOS) exposure on glucose-stimulated insulin secretion (GSIS) of rat insulinoma (INS-1) cells and the potential protective effects of procyanidins (PC). The effects of PFOS and/or PC on GSIS of INS-1 cells were investigated after 48 h of exposure (protein level: insulin; gene level: glucose transporter 2 (Glut2), glucokinase (Gck), and insulin). Subsequently, the effects of exposure on the intracellular reactive oxygen species (ROS) activity were measured. Compared to the control group, PFOS exposure (12.5, 25, and 50 μM) for 48 h had no significant effect on the viability of INS-1 cells. PFOS exposure (50 μM) could reduce the level of insulin secretion and reduce the relative mRNA expression levels of Glut2, Gck, and insulin. It is worth noting that PC could partially reverse the damaging effect caused by PFOS. Significantly, there was an increase in ROS after exposure to PFOS and a decline after PC intervention. PFOS could affect the normal physiological function of GSIS in INS-1 cells. PC, a plant natural product, could effectively alleviate the damage caused by PFOS by inhibiting ROS activity. Full article

Maturity-onset diabetes of the young (MODY) is a rare form of non-autoimmune diabetes with an autosomal dominant inheritance. To date, 14 genes have been reported as genetic basis of MODY. GCK gene, encoding the glucokinase enzyme, was the first MODY gene to be identified. GCK heterozygous inactivating variants cause the GCK-MODY or MODY2 subtype. However, partial or whole gene deletions have been rarely identified, showing it to be a rare cause of GCK-MODY. We reported the molecular evaluation of a Ukrainian patient with clinical diagnosis of MODY2. We performed the Next generation sequencing of the clinical exome using the Clinical Exome Solution^® kit (SOPHiA Genetics), followed by the design of a 14 genes virtual panel related to the suggestive diagnosis of MODY. Bioinformatics analysis was performed using the SOPHiA DDM platform (SOPHiA Genetics). The SALSA MLPA kit for MODY (MRC-Holland) was used for relative quantification of GCK exons. From the molecular evaluation, no pathogenic sequence variants were detected in the investigated genes. Copy Number Variation analysis was able to identify a large deletion involving the last three exons of the GCK gene. This result was confirmed by MLPA. To the best of our knowledge, the identified rearrangement has never been reported in the literature. Full article