Effect of glucokinase regulatory protein (GCKR)-rs1260326 on gene expression in human liver organoids
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE213932 | GEO | 2022/10/13
REPOSITORIES: GEO
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Project description:BackgroundGlucokinase (GCK) plays an important role in the regulation of carbohydrate metabolism. In the liver, phosphorylation of glucose to glucose-6-phosphate by GCK is the first step for both glycolysis and glycogen synthesis. However, some vertebrate species are deficient in GCK activity in the liver, despite containing GCK genes that appear to be compatible with function in their genomes. Glucokinase regulatory protein (GCKR) is the most important post-transcriptional regulator of GCK in the liver; it participates in the modulation of GCK activity and location depending upon changes in glucose levels. In experimental models, loss of GCKR has been shown to associate with reduced hepatic GCK protein levels and activity.Methodology/principal findingsGCKR genes and GCKR-like sequences were identified in the genomes of all vertebrate species with available genome sequences. The coding sequences of GCKR and GCKR-like genes were identified and aligned; base changes likely to disrupt coding potential or splicing were also identified.Conclusions/significanceGCKR genes could not be found in the genomes of 9 vertebrate species, including all birds. In addition, in multiple mammalian genomes, whereas GCKR-like gene sequences could be identified, these genes could not predict a functional protein. Vertebrate species that were previously reported to be deficient in hepatic GCK activity were found to have deleted (birds and lizard) or mutated (mammals) GCKR genes. Our results suggest that mutation of the GCKR gene leads to hepatic GCK deficiency due to the loss of the stabilizing effect of GCKR.
| S-EPMC3613411 | biostudies-literature
Project description:ObjectiveRecent studies in European populations have reported a reciprocal association of glucokinase regulatory protein (GCKR) gene with triglyceride versus fasting plasma glucose (FPG) levels and type 2 diabetes risk. GCKR is a rate-limiting factor of glucokinase (GCK), which functions as a key glycolytic enzyme for maintaining glucose homeostasis. We examined the associations of two common genetic polymorphisms of GCKR and GCK with metabolic traits in healthy Chinese adults and adolescents.Research design and methodsTwo single nucleotide polymorphisms (SNPs), rs780094 at GCKR and rs1799884 at GCK, were genotyped in 600 healthy adults and 986 healthy adolescents. The associations of these SNPs with metabolic traits were assessed by linear regression adjusted for age, sex, and/or BMI. We also tested for the epistasis between these two SNPs and performed a meta-analysis among European and Asian populations.ResultsThe T-allele of GCKR rs780094 was associated with increased triglycerides (P = 5.4 x 10(-7)), while the A-allele of GCK rs1799884 was associated with higher FPG (P = 3.1 x 10(-7)). A novel interaction effect between the two SNPs on FPG was also observed (P = 0.0025). Meta-analyses strongly supported the additive effects of the two SNPs on FPG and triglycerides, respectively. CONCLUSIONS;- In support of the intimate relationship between glucose and lipid metabolisms, GCKR and GCK genetic polymorphisms interact to increase FPG in healthy adults and adolescents. These risk alleles may contribute to increased diabetes risk in subjects who harbor other genetic or environmental/lifestyle risk factors.
| S-EPMC2646078 | biostudies-literature
Project description:Recently, the single nucleotide polymorphism (SNP) identified as rs1260326, in the glucokinase regulatory protein (GCKR), was associated with hypertriglyceridemia in adults. Because accumulation of triglycerides in hepatocytes represents the hallmark of steatosis, we aimed to investigate whether this variant might be associated with fatty liver (hepatic fat content, HFF%). Moreover, because recently rs738409 in the PNPLA3 and rs2854116 in the APOC3 were associated with fatty liver, we explored how the GCKR SNP and these two variants jointly influence hepatosteatosis. We studied 455 obese children and adolescents (181 Caucasians, 139 African Americans, and 135 Hispanics). All underwent an oral glucose tolerance test and fasting lipoprotein subclasses measurement by proton nuclear magnetic resonance. A subset of 142 children underwent a fast gradient magnetic resonance imaging to measure the HFF%. The rs1260326 was associated with elevated triglycerides (Caucasians P = 0.00014; African Americans P = 0.00417), large very low-density lipoprotein (VLDL) (Caucasians P = 0.001; African Americans, P = 0.03), and with fatty liver (Caucasians P = 0.034; African Americans P = 0.00002; and Hispanics P = 0.016). The PNPLA3, but not the APOC3 rs2854116 SNP, was associated with fatty liver but not with triglyceride levels. There was a joint effect between the PNPLA3 and GCKR SNPs, explaining 32% of HFF% variance in Caucasians (P = 0.00161), 39.0% in African Americans (P = 0.00000496), and 15% in Hispanics (P = 0.00342).The rs1260326 in GCKR is associated with hepatic fat accumulation along with large VLDL and triglyceride levels. GCKR and PNPLA3 act together to convey susceptibility to fatty liver in obese youths.
| S-EPMC3288435 | biostudies-literature
Project description:Hypertriglyceridemia is a risk factor for cardiovascular disease. Variation in the apolipoprotein A5 (APOA5) and glucokinase regulatory protein (GCKR) genes has been associated with fasting plasma triacylglycerol.We investigated the combined effects of the GCKR rs780094C-->T, APOA5 -1131T-->C, and APOA5 56C-->G single nucleotide polymorphisms (SNPs) on fasting triacylglycerol in several independent populations and the response to a high-fat meal and fenofibrate interventions.We used a cross-sectional design to investigate the association with fasting triacylglycerol in 8 populations from America, Asia, and Europe (n = 7,730 men and women) and 2 intervention studies in US whites (n = 1,061) to examine postprandial triacylglycerol after a high-fat meal and the response to fenofibrate. We defined 3 combined genotype groups: 1) protective (homozygous for the wild-type allele for all 3 SNPs); 2) intermediate (any mixed genotype not included in groups 1 and 3); and 3) risk (carriers of the variant alleles at both genes).Subjects within the risk group had significantly higher fasting triacylglycerol and a higher prevalence of hypertriglyceridemia than did subjects in the protective group across all populations. Moreover, subjects in the risk group had a greater postprandial triacylglycerol response to a high-fat meal and greater fenofibrate-induced reduction of fasting triacylglycerol than did the other groups, especially among persons with hypertriglyceridemia. Subjects with the intermediate genotype had intermediate values (P for trend <0.001).SNPs in GCKR and APOA5 have an additive effect on both fasting and postprandial triacylglycerol and contribute to the interindividual variability in response to fenofibrate treatment.
| S-EPMC2647710 | biostudies-literature
Project description:Glucokinase (GCK) is responsible for maintaining glucose homeostasis in the human body. Dysfunction or misregulation of GCK causes hyperinsulinemia, hypertriglyceridemia, and type 2 diabetes. In the liver, GCK is regulated by interaction with the glucokinase regulatory protein (GKRP), a 68 kDa polypeptide that functions as a competitive inhibitor of glucose binding to GCK. Formation of the mammalian GCK-GKRP complex is stimulated by fructose 6-phosphate and antagonized by fructose 1-phosphate. Here we report the crystal structure of the mammalian GCK-GKRP complex in the presence of fructose 6-phosphate at a resolution of 3.50 Å. The interaction interface, which totals 2060 Å(2) of buried surface area, is characterized by a small number of polar contacts and substantial hydrophobic interactions. The structure of the complex reveals the molecular basis of disease states associated with impaired regulation of GCK by GKRP. It also offers insight into the modulation of complex stability by sugar phosphates. The atomic description of the mammalian GCK-GKRP complex provides a framework for the development of novel diabetes therapeutic agents that disrupt this critical macromolecular regulatory unit.
| S-EPMC3859847 | biostudies-literature
Project description:Glucokinase (GCK) is the rate-limiting enzyme of liver glucose metabolism. Through protein-protein interactions, glucokinase regulatory protein (GCKR) post-transcriptionally regulates GCK function in the liver, and causes its nuclear localization. However the role of GCK in regulating GCKR localization is unknown. In the present study, using in vitro and in vivo models, we examined the levels of GCK and GCKR, and their subcellular localization. We found that total cellular levels of GCKR did not vary in the in vivo models, but its subcellular localization did. In animals with normal levels of GCK, GCKR is mainly localized to the nuclei of hepatocytes. In seven-day old rats and liver-specific Gck gene knockout mice (animals that lack or have reduced levels of GCK protein), GCKR was found primarily in the cytoplasm. The interaction of GCK with GCKR was further examined using in vitro models where we varied the levels of GCK and GCKR. Varying the level of GCK protein had no effect on total cellular GCKR protein levels. Taken together, our results indicate that GCK is important for the localization of GCKR to the nucleus and raises the possibility that GCKR may have functions in addition to those regulating GCK activity in the cytoplasm.
| S-EPMC4425023 | biostudies-literature
Project description:Cervical cancer (CC) is a complex disease. Many factors contribute to the tumourigenesis and progression of CC neoplasms. Here, we analysed transcriptomic differences and simulated tumour progression to explore the pathogenesis of CC. RNA-seq was performed to analyse the transcriptomic differences among normal tissue (NC), paracarcinoma tissue (TP), and primary tumour tissue (TT). Pseudo-time analysis was performed to simulate tumour progression. RT-qPCR and immunohistochemistry were used to analyse the expression of ISG15. Cell proliferation, wound healing, and Transwell assays were used to verify the effect of ISG15 on HeLa cells. The RT-qPCR and immunohistochemistry results indicated that ISG15 had significantly higher expression in TT. We observed an increasing trend of ISG15 expression from NC to TP to TT, which suggests that elevated expression of ISG15 was closely associated with malignant evolution in CC tissues. HeLa cell experiments showed that ISG15-siRNA inhibited cell proliferation and invasion. Our study verifies that ISG15 is upregulated in and positively associated with the development of CC. ISG15 may act as an oncogene in the tumourigenesis of CC.
2022-01-02 | GSE192804 | GEO
Project description:Glucokinase (GK), mainly expressed in the liver and pancreatic β-cells, is critical for maintaining glucose homeostasis. GK expression and kinase activity, respectively, are both modulated at the transcriptional and post-translational levels. Post-translationally, GK is regulated by binding the glucokinase regulatory protein (GKRP), resulting in GK retention in the nucleus and its inability to participate in cytosolic glycolysis. Although hepatic GKRP is known to be regulated by allosteric mechanisms, the precise details of modulation of GKRP activity, by post-translational modification, are not well known. Here, we demonstrate that GKRP is acetylated at Lys5 by the acetyltransferase p300. Acetylated GKRP is resistant to degradation by the ubiquitin-dependent proteasome pathway, suggesting that acetylation increases GKRP stability and binding to GK, further inhibiting GK nuclear export. Deacetylation of GKRP is effected by the NAD(+)-dependent, class III histone deacetylase SIRT2, which is inhibited by nicotinamide. Moreover, the livers of db/db obese, diabetic mice also show elevated GKRP acetylation, suggesting a broader, critical role in regulating blood glucose. Given that acetylated GKRP may affiliate with type-2 diabetes mellitus (T2DM), understanding the mechanism of GKRP acetylation in the liver could reveal novel targets within the GK-GKRP pathway, for treating T2DM and other metabolic pathologies.
| S-EPMC4664969 | biostudies-literature
Project description:The glucokinase regulatory protein (GKRP) is a competitive inhibitor of glucokinase (GCK), triggering its localization to the hepatocyte nucleus upon glucose deprivation. Here we establish the kinetic mechanism of GKRP action by analyzing its association with a genetically encoded, fluorescent variant of human GCK. Our results demonstrate that binding of GKRP to GCK involves two steps, formation of an initial encounter complex followed by conformational equilibration between two GKRP-GCK states. Fructose 6-phosphate, a known enhancer of GKRP action, promotes formation of the initial encounter complex via a 2.6-fold increase in kon and stabilizes the complex through a 60-fold decrease in koff.
| S-EPMC7140980 | biostudies-literature
Project description:Glucokinase (GK) is a monomeric allosteric enzyme and plays a pivotal role in blood glucose homeostasis. GK is regulated by GK regulatory protein (GKRP), and indirectly by allosteric effectors of GKRP. Despite the critical roles of GK and GKRP, the molecular basis for the allosteric regulation mechanism of GK by GKRP remains unclear. We determined the crystal structure of Xenopus GK and GKRP complex in the presence of fructose-6-phosphate at 2.9 Å. GKRP binds to a super-open conformation of GK mainly through hydrophobic interaction, inhibiting the GK activity by locking a small domain of GK. We demonstrate the molecular mechanism for the modulation of GK activity by allosteric effectors of GKRP. Importantly, GKRP releases GK in a sigmoidal manner in response to glucose concentration by restricting a structural rearrangement of the GK small domain via a single ion pair. We find that GKRP acts as an allosteric switch for GK in blood glucose control by the liver.
| S-EPMC3690866 | biostudies-literature