Massive Expansion of Functional Human iPSC-derived Cardiomyocytes by Concomitant Glycogen Synthase Kinase-3 Beta Inhibition and Removal of Cell-Cell Contact
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ABSTRACT: Massive Expansion of Functional Human iPSC-derived Cardiomyocytes by Concomitant Glycogen Synthase Kinase-3 Beta Inhibition and Removal of Cell-Cell Contact
Project description:Modulating signaling pathways including Wnt and Hippo can induce cardiomyocyte proliferation in vivo. Applying these signaling modulators to human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in vitro can expand CMs only to modest extent (< 5-fold). Here, we demonstrate massive expansion of hiPSC-CMs in vitro (i.e. 100-250-fold) by glycogen synthase kinase-3β (GSK-3β) inhibition using CHIR99021 and concurrent removal of cell-cell contact. We show GSK-3β inhibition suppresses CM maturation while contact removal prevents CMs from cell cycle exit. Remarkably, contact removal enabled 10-to-25-times greater expansion beyond GSK-3β inhibition alone. Mechanistically, cell cycle re-activation required both LEF/TCF activity and AKT phosphorylation, but it was independent from Yes associated protein (YAP) activity. Engineered heart tissues from expanded hiPSC-CMs showed the comparable contractility to those from unexpanded hiPSC-CMs, demonstrating uncompromised cellular functionality after expansion. In sum, we uncovered a molecular interplay that enables massive expansion hiPSC-CMs for large-scale drug screening and tissue engineering.
Project description:Anterior tibialis removed from 3-month old muscle glycogen synthase WT or knockout mouse. RNA was extracted using GibcoBRL TRIzol Reagent and a Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 5ug of total RNA. GSM40057-GSM40063 AND GSM40956. Liver removed from 3-month old muscle glycogen synthase WT or knockout mouse. RNA was extracted using GibcoBRL TRIzol Reagent and a Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 10ug of total RNA. GSM40064-GSM40071. Medial gastrocnemius removed from 3-month old muscle glycogen synthase WT or knockout mouse. RNA was extracted using GibcoBRL TRIzol Reagent and a Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 5ug of total RNA. GSM40072-GSM40079. Medial gastrocnemius removed from 8-month old muscle glycogen synthase WT or overexpressing mouse. RNA was extracted using GibcoBRL TRIzol Reagent and a Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 5ug of total RNA. GSM40080-GSM40089 Keywords: other
Project description:Anterior tibialis removed from 3-month old muscle glycogen synthase WT or knockout mouse. RNA was extracted using GibcoBRL TRIzol Reagent and a Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 5ug of total RNA. GSM40057-GSM40063 AND GSM40956. Liver removed from 3-month old muscle glycogen synthase WT or knockout mouse. RNA was extracted using GibcoBRL TRIzol Reagent and a Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 10ug of total RNA. GSM40064-GSM40071. Medial gastrocnemius removed from 3-month old muscle glycogen synthase WT or knockout mouse. RNA was extracted using GibcoBRL TRIzol Reagent and a Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 5ug of total RNA. GSM40072-GSM40079. Medial gastrocnemius removed from 8-month old muscle glycogen synthase WT or overexpressing mouse. RNA was extracted using GibcoBRL TRIzol Reagent and a Quiagen RNeasy kit. Targets were produced using standard Affymetrix procedures from about 5ug of total RNA. GSM40080-GSM40089
Project description:In this study, we aimed at uncovering the molecular mechanisms underlying POMC neuron sensory activation and the mediated behavioral and metabolic processes. Unexpectedly, we found that glycogen metabolism is rapidly engaged in POMC neurons upon sensory food perception. Genetic deletion of glycogen synthase, the sole enzyme able to make glycogen in vivo, in POMC neurons impedes food-related sensory activation while causing impairments in food awareness, short-term food intake and insulin release. These perturbations associate with whole-body metabolic defects, including overweight and insulin resistance, that are exacerbated by high-dense diets or ageing. Collectively, our study identifies glycogen metabolism as an unanticipated mechanistic driver of POMC neuron sensory activation and provides paradigm-shift evidences of the importance of neuronal glycogen for physiology.
Project description:Glucocorticoids (GCs) bind to the glucocorticoid receptor (GR) to regulate diverse biological functions from cell growth to apoptosis. Drugs that mimic their action are the most commonly prescribed therapeutic agents in the world and are currently used for the treatment of many diseases including asthma, autoimmune disorders, and some cancers. However, the mechanisms by which one hormone, via one receptor, modulates such diverse biological functions remain unclear. We hypothesized that epigenetic alteration to the GR may contribute to its signaling diversity, and here we demonstrate that Glycogen Synthase Kinase-3-beta phosphorylates GR on Serine 404 in a glucocorticoid-dependent manner. U-2 OS cells expressing a mutant GR that is incapable of Ser404 phosphorylation have enhanced global transcriptional responses, stronger NF-kappaB transrepression, and enhanced cell death in response to dexamethasone. Conversely, presence of Ser404 phosphorylation on the GR inhibits glucocorticoid-dependent NF-kappaB transrepression and cell death of these osteoblasts. Collectively, our results describe a novel convergence point of the GSK-3-beta pathway with the GR resulting in altered glucocorticoid regulated signaling. Our results also provide a mechanism by which the phosphorylation status of Ser404 in GR can dictate how cells will ultimately respond to GCs. Keywords: Glucocorticoid Receptor; GSK-3-beta; NF-kappaB Transrepression; Phosphorylation
Project description:Glycogenin is considered essential for glycogen synthesis as it acts as a primer for the initiation of the polysaccharide. In this study, we challenge this notion and demonstrate that glycogen can be synthesized in vivo in the absence of glycogenin. Glycogenin-deficient mice (Gyg KO) accumulate high amounts of the polysaccharide in skeletal and cardiac striated muscles. This glycogen shows no covalently bound protein, thereby indicating that no protein primer is essential for glycogen synthesis. Gyg KO mice show lower resting energy expenditure and lesser resistance when subjected to endurance exercise than control animals, which can be attributed to a switch of oxidative myofibers toward glycolytic metabolism. This switch is caused by the over-accumulation of glycogen, since mice overexpressing glycogen synthase specifically in skeletal muscle show a similar metabolic alteration. These results may explain the muscular defects of GSD XV patients, who show high glycogen accumulation in striated muscles.
Project description:Glycogen and lipid are major storage forms of energy that are tightly regulated by hormones and metabolic signals. Here, we evaluate the role of the glycogenic scaffolding protein PTG/R5 in energy homeostasis. We demonstrate that feeding mice a high-fat diet (HFD) increases hepatic glycogen, corresponding to increased PTG levels, increased activity of the mechanistic target of rapamycin complex 1 (mTORC1) and induced expression of sterol regulatory element binding protein 1c (SREBP1c). PTG promoter activity was increased by activation of mTORC1 and SREBP1, and PTG and glycogen levels were augmented in mice and cells in which mTORC1 is constitutively active. HFD-dependent increases in hepatic glycogen were prevented by deletion of the PTG gene in mice. Interestingly, PTG knockout mice fed HFD exhibited improved liver steatosis and decreased lipid levels in muscle, in coordination with decreased glycogen, suggesting possible crosstalk between glycogen and lipid stores in the overall control of energy metabolism. Together, these data suggest that transcriptional regulation of PTG by dietary and nutritional cues has profound effects on energy storage and metabolism.fi RNA-Seq analysis was used to characterize hepatic diet-associated gene expression changes between wild-type and PTG KO mice. Mice were maintained on a normal chow diet or a high-fat diet as indicated. 2-3 biological replicates per genotype/diet.
Project description:Glycogen and lipid are major storage forms of energy that are tightly regulated by hormones and metabolic signals. Here, we evaluate the role of the glycogenic scaffolding protein PTG/R5 in energy homeostasis. We demonstrate that feeding mice a high-fat diet (HFD) increases hepatic glycogen, corresponding to increased PTG levels, increased activity of the mechanistic target of rapamycin complex 1 (mTORC1) and induced expression of sterol regulatory element binding protein 1c (SREBP1c). PTG promoter activity was increased by activation of mTORC1 and SREBP1, and PTG and glycogen levels were augmented in mice and cells in which mTORC1 is constitutively active. HFD-dependent increases in hepatic glycogen were prevented by deletion of the PTG gene in mice. Interestingly, PTG knockout mice fed HFD exhibited improved liver steatosis and decreased lipid levels in muscle, in coordination with decreased glycogen, suggesting possible crosstalk between glycogen and lipid stores in the overall control of energy metabolism. Together, these data suggest that transcriptional regulation of PTG by dietary and nutritional cues has profound effects on energy storage and metabolism.fi
Project description:Background: Heart failure involves metabolic alterations including increased glycolysis despite unchanged or decreased glucose oxidation. The mitochondrial pyruvate carrier (MPC) regulates pyruvate entry into the mitochondrial matrix, and cardiac deletion of the MPC in mice causes heart failure. How MPC deletion results in heart failure is unknown. Methods: We performed targeted metabolomics and isotope tracing in wildtype (fl/fl) and cardiac-specific Mpc2-/- (CS-Mpc2-/-) hearts after in vivo injection of 13C-glucose. Cardiac glycogen was measured biochemically and by transmission electron microscopy. Cardiac glucose uptake of 2-deoxyglucose was measured and western blotting performed to analyze insulin signaling and enzymatic regulators of glycogen synthesis and degradation. Isotope tracing and glycogen analysis was also performed in hearts from mice fed either low-fat diet or a ketogenic diet previously shown to reverse the heart failure in CS-Mpc2-/- mice. Cardiac glycogen was also assessed in mice infused with angiotensin-II that were fed either low-fat or ketogenic diet. Results: Failing CS-Mpc2-/- hearts contained normal levels of ATP and phosphocreatine, suggesting their heart failure is not caused by energetic stress. These hearts displayed increased enrichment from 13C-glucose and increased glycolytic metabolite pool sizes. 13C enrichment and pool size was also increased for the glycogen intermediate UDP-glucose, as well as increased enrichment of the glycogen pool. Glycogen levels were increased ~6-fold in the failing CS-Mpc2-/- hearts, and glycogen granules were easily detected by electron microscopy. This increased glycogen synthesis occurred despite enhanced inhibitory phosphorylation of glycogen synthase and reduced expression of the priming enzyme glycogenin-1. In young, non-failing CS-Mpc2-/- hearts, increased glycolytic 13C enrichment occurred, but glycogen levels remained low and unchanged compared to fl/fl hearts. Feeding a ketogenic diet to CS-Mpc2-/- mice reversed the heart failure and normalized the cardiac glycogen and glycolytic metabolite accumulation. Cardiac glycogen levels were also elevated in mice infused with angiotensin II, and both the cardiac hypertrophy and glycogen levels were improved by ketogenic diet. Conclusions: Our results indicate that loss of MPC in the heart increases glycolytic metabolism and ultimately glycogen accumulation and heart failure, while a ketogenic diet can reverse both the glycogen accumulation and heart failure. We conclude that maintaining mitochondrial pyruvate import and metabolism is critical for the heart, unless cardiac pyruvate metabolism is dramatically reduced by consumption of a ketogenic diet.
Project description:Embryonic and epiblast stem cells in pre-and post-implantation embryos are characterized by their naïve and primed states, respectively, which represent distinct phases of pluripotency. Thus, the cellular transition from naïve to primed pluripotency recapitulates a drastic metabolic and cellular remodeling after implantation to adapt to changes in extracellular conditions. Here, we found that inhibition of Ampk occurred during naïve transition with two conventional inhibitors (2i) of the Mek1 and Gsk3 pathways. The accumulation of glycogen due to the inhibition of Gsk3 was responsible for Ampk inhibition, which accounted for high de novo fatty acid synthesis in naïve embryonic stem cells (ESCs). The knockout of glycogen synthase 1 (Gys1) in naïve ESCs (GKO), resulting in a drastic glycogen loss, led to a robust Ampk activation and lowered the level of fatty acids. GKO lost the cellular characteristics of naïve ESCs and rapidly transitioned to a primed state. The characteristics of GKO were restored by the simultaneous knockout of Ampk. These findings suggest that glycogen in naïve ESCs within the blastocyst may act as a signaling molecule for the timely activation of Ampk, thus ultimately contributing to the transition to the epiblast stage.