Ontology highlight
ABSTRACT:
PROVIDER: PRJNA281885 | ENA |
REPOSITORIES: ENA
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Project description:Decreasing glucagon action lowers blood glucose and may be a useful therapeutic approach for diabetes. However, interrupted glucagon signaling in mice leads to hyperglucagonemia and α-cell hyperplasia. We show using islet transplantation, mouse and zebrafish models, an in vitro islet culture assay that a hepatic-derived, circulating factor in mice with interrupted glucagon signaling stimulates α-cell proliferation, which was dependent on mTOR signaling and the FoxP transcription factors. α-cells of transplanted human islets also proliferated in response to this signal in mice. A combination of liver transcriptomics and serum fractionation with proteomics/metabolomics found changes in hepatic gene expression relating to amino acid catabolism predicting the observed increase in serum amino acid levels. Amino acid concentrations that mimicked the levels in mice with interrupted glucagon signaling, specifically L-glutamine, stimulated α-cell proliferation. These results indicate a hepatic-α-islet cell axis where glucagon regulates serum amino acid availability and L-glutamine regulates α-cell proliferation via mTOR-dependent nutrient sensing.
2017-03-31 | GSE89035 | GEO
Project description:Objective: Activation of the liver glucagon receptor (GCGR) promotes amino acid catabolism, which provides substrate for glucose production. Inhibition of the receptor downregulates hepatic amino acid catabolism, leading to increases in circulating amino acid levels. Amino acids serve as a potent growth factor for pancreatic alpha cells, where glucagon is produced. Thus, GCGR inhibition-induced hyperaminoacidemia causes alpha cell hyperplasia. This liver-alpha cell feedback loop, mediated by glucagon and amino acids, has been demonstrated across species, including humans. This study was designed to delineate hepatic signaling molecules that lie downstream of GCGR and mediate the liver-alpha cell loop. Methods: We used AAV8-shRNA to knock down GCGR signaling molecules, the G-coupled protein GNAS and two GNAS downstream effectors, PKA and EPAC2 (RAPGEF4), in the liver of diet-induced obese (DIO) mice. We monitored plasma amino acid and blood glucose levels and conducted pancreas histology to derive alpha and beta cell mass. We performed liver RNA-sequencing to assess expression of glucose and amino acid metabolism genes. To examine the contribution of PKA in changes associated with GCGR inhibition, we knocked down PRKAR1A, a major inhibitory subunit of PKA, to activate PKA in liver of mice administered with GCGR blocking or control antibody. Results: Comparable suppression of hepatic amino acid catabolism gene expressions, increases in plasma amino acid levels and alpha cell hyperplasia were observed in mice with hepatic knockdown of GCGR, GNAS, and PKA. Hepatic EPAC2 knockdown did not affect amino acid metabolism or alpha cell mass in mice. Mice with hepatic PKA activation alone developed hypoaminoacidemia, hypoglucagonemia and reduced alpha cell mass. Administering GCGR blocking antibody to the mice did not alter the abnormalities. Conclusions: Hepatic PKA activation in mice fully overrides the effect of GCGR inhibition on amino acids and alpha cells. In the liver, GCGR signals through PKA to control amino acid metabolism and pancreatic alpha cell mass. Hepatic PKA plays a critical role in the liver-alpha cell loop, mediated by circulating glucagon and amino acids.
2025-05-30 | GSE268864 | GEO
Project description:Glucagon supports glucose homeostasis by stimulating hepatic gluconeogenesis, in part by promoting the uptake and conversion of amino acids into gluconeogenic precursors. Genetic disruption or pharmacologic inhibition of glucagon signaling results in elevated plasma amino acids, and compensatory glucagon hypersecretion involving expansion of pancreatic α-cell mass. Regulation of pancreatic α- and β-cell growth has drawn a lot of attention because of potential therapeutic implications. Recent findings indicate that hyperaminoacidemia triggers pancreatic α-cell proliferation via an mTOR-dependent pathway. We confirm and extend these findings by demonstrating that glucagon pathway blockade selectively increases expression of the sodium-coupled neutral amino acid transporter Slc38a5 in a subset of highly proliferative α-cells, and that Slc38a5 is critical for the pancreatic response to glucagon pathway blockade; most notably, mice deficient in Slc38a5 exhibit markedly decreased α-cell hyperplasia to glucagon pathway blockade-induced hyperaminoacidemia. These results show that Slc38a5 is a key component of the feedback circuit between glucagon receptor signaling in the liver and amino acid-dependent regulation of pancreatic α-cell mass in mice.
2017-05-01 | GSE89636 | GEO
Project description:Glucagon supports glucose homeostasis by stimulating hepatic gluconeogenesis, in part by promoting the uptake and conversion of amino acids into gluconeogenic precursors. Genetic disruption or pharmacologic inhibition of glucagon signaling results in elevated plasma amino acids and compensatory glucagon hypersecretion involving expansion of pancreatic a cell mass. Recent findings indicate that hyperaminoacidemia triggers pancreatic a cell proliferation via an mTOR-dependent pathway. We confirm and extend these findings by demonstrating that glucagon pathway blockade selectively increases expression of the sodium-coupled neutral amino acid transporter Slc38a5 in a subset of highly proliferative a cells and that Slc38a5 controls the pancreatic response to glucagon pathway blockade; most notably, mice deficient in Slc38a5 exhibit markedly decreased a cell hyperplasia to glucagon pathway blockade-induced hyperaminoacidemia. These results show that Slc38a5 is a key component of the feedback circuit between glucagon receptor signaling in the liver and amino-acid-dependent regulation of pancreatic a cell mass in mice.
2017-06-21 | GSE90116 | GEO
Project description:Glucagon is a key regulator of glucose homeostasis, amino acid catabolism, and lipid metabolism. Glucagon receptor knock-out (GcgrKO) mice have slightly reduced blood glucose levels whereas plasma levels of amino acids are vastly increased reflecting disruption of hepatic amino acid catabolism. To dissect the molecular mechanisms underlying this effect, RNA sequencing of livers from male GcgrKO mice and wild-type littermates were performed. The mice were 10 weeks of age and were subjected to a short-term fast of 4 h before anesthesia with 2.5% isoflurane.
2022-10-11 | E-MTAB-12060 | biostudies-arrayexpress
Project description:Chronic glucagon receptor activation with a long-acting glucagon analogue increases amino acid catabolism, and to dissect the molecular mechanism underlying this effect, RNA sequencing of liver biopsies from female mice treated for eight weeks with GCGA or PBS were performed.
2022-10-11 | E-MTAB-12040 | biostudies-arrayexpress
Project description:Chronic glucagon receptor inhibition with a glucagon receptor antibody decreases amino acid catabolism and ureagenesis, while increasing plasma triglyceride concentrations, plasma very-low density lipoprotein cholesterol concentrations, and liver triglyceride concentrations. To dissect the molecular mechanism underlying these effects, RNA sequencing of liver biopsies from female mice treated for eight weeks with the glucagon receptor antibody, REGN1193, or a control antibody, REGN1945, were performed.
2022-10-09 | E-MTAB-12048 | biostudies-arrayexpress
Project description:Glucagon has recently been found to modulate liver fat content, in addition to its role in regulating gluconeogenesis. However, the precise mechanisms by which glucagon signaling synchronizes glucose and lipid metabolism in the liver remain poorly understood. By employing chemical and genetic approaches, we demonstrate that inhibiting the androgen receptor (AR) impairs the ability of glucagon to stimulate gluconeogenesis and lipid catabolism in primary hepatocytes and female mice. Notably, AR expression in the liver of female mice is up to three times higher than that in their male littermates, accounting for the more pronounced response to glucagon in females. Mechanistically, hepatic AR promotes energy metabolism and enhances lipid breakdown for liver glucose production in response to glucagon treatment through the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α)/estrogen-related receptor alpha (ERRα)-mitochondria axis. Overall, our findings highlight the crucial role of hepatic AR in mediating glucagon signaling and the sexual dimorphism in hepatic glucagon sensitivity.
2025-01-01 | GSE261197 | GEO
Project description:Glucagon has recently been found to modulate liver fat content, in addition to its role in regulating gluconeogenesis. However, the precise mechanisms by which glucagon signaling synchronizes glucose and lipid metabolism in the liver remain poorly understood. By employing chemical and genetic approaches, we demonstrate that inhibiting the androgen receptor (AR) impairs the ability of glucagon to stimulate gluconeogenesis and lipid catabolism in primary hepatocytes and female mice. Notably, AR expression in the liver of female mice is up to three times higher than that in their male littermates, accounting for the more pronounced response to glucagon in females. Mechanistically, hepatic AR promotes energy metabolism and enhances lipid breakdown for liver glucose production in response to glucagon treatment through the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α)/estrogen-related receptor alpha (ERRα)-mitochondria axis. Overall, our findings highlight the crucial role of hepatic AR in mediating glucagon signaling and the sexual dimorphism in hepatic glucagon sensitivity.
2025-01-01 | GSE236551 | GEO
Project description:Glutarate is an intermediate of amino acid catabolism and an important metabolite for reprogramming T cell immunity, exerting its effects by inhibition of histone demethylase enzymes or through glutarylation. However, how distinct glutarate modifications are regulated is unclear. Here, we uncover a deglutarylation pathway that couples amino acid catabolism to tricarboxylic acid (TCA) cycle function. By examining how glutarate can form conjugates with lipoate, an essential mitochondrial modification for the TCA cycle, we find that Alpha Beta Hydrolase Domain 11 (ABHD11) protects against the formation of glutaryl-lipoyl adducts. Mechanistically, ABHD11 acts as a thioesterase to selectively remove glutaryl adducts from lipoate, maintaining integrity of the TCA cycle. Functionally, ABHD11 influences the metabolic reprogramming of human T cells, increasing central memory T cell formation and attenuating oxidative phosphorylation. These results uncover ABHD11 as a selective deglutarylating enzyme and highlight that targeting ABHD11 offers a potential approach to metabolically reprogramme cytotoxic T cells.
2025-05-23 | GSE292544 | GEO