M6A-eCLIP sequencing in mouse alpha cell line aTC1-6 cells with Scramble or Mettl14 KD
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE279020 | GEO | 2026/07/08
REPOSITORIES: GEO
Similar Datasets
Project description:Glucagon is secreted from pancreatic α-cells, and hypersecretion (hyperglucagonemia) contributes to diabetic hyperglycemia. Molecular heterogeneity in hyperglucagonemia is poorly investigated. By screening human plasma by high-resolution-proteomics, we identified several glucagon variants among which proglucagon 1-61 (PG 1-61) appears to be the most abundant form. PG 1-61 was secreted in obese subjects before and as well after gastric bypass surgery with protein and fat as the main drivers for secretion before surgery, but glucose after. Studies in hepatocytes and in β-cells demonstrated that PG 1-61 dose-dependently increased levels of cAMP, through the glucagon receptor, and increased insulin secretion and protein levels of enzymes regulating glycogenolysis and gluconeogenesis. As a consequence, PG 1-61 increased blood glucose and plasma insulin and decreased plasma levels of amino acids in vivo. Glucagon variants, such as PG 1-61, may contribute to glucose regulation by stimulating hepatic glucose production and insulin secretion.
2017-10-20 | PXD005677 | Pride
Project description:Inappropriate glucagon secretion deteriorates glycemic control in type 1 and type 2 diabetes. While insulin is known to regulate glucagon secretion via its receptor in alpha cells, the role of downstream proteins and signaling pathways underlying the actions of insulin are not fully defined. Using in vivo (knockout) and in vitro (knockdown) studies targeting insulin receptor substrate (IRS) proteins, we compared the relative roles of IRS1 versus IRS2 in regulating alpha cell function. Alpha cell-specific IRS1 knock out (alpha IRS1KO) mice exhibit glucose intolerance and inappropriate glucagon suppression during glucose-tolerance tests. In contrast, alpha cell-specific IRS2 knock outs (alpha IRS2KO) manifest normal glucose tolerance and suppression of glucagon secretion after glucose administration. Alpha cell lines with stable knockdown of IRS1 (alpha IRS1KD) are unable to repress glucagon mRNA expression and exhibit reduction in phosphorylation of AKT. However, glucagon mRNA expression was suppressed in response to insulin stimulation in a stable IRS2 knock down alpha cell line (alpha IRS2KD). Alpha IRS1KD cells also display suppressed global protein translation including glucagon, impaired cytoplasmic Ca2+ response and mitochondrial function. These data argue for IRS1 as a dominant regulator of pancreatic alpha cell function.
2021-04-07 | GSE130329 | GEO
Project description:Hyglucagonemia is a hallmark of diabetes caused by dysregulation of glucagon secretion by pancreatic alpha-cells. Although glucose sensing and insulin signaling are well-established regulators, the pathways governing glucagon secretion are not fully understood. Recent evidences suggest that insulin-degrading enzyme (IDE) regulates glucagon secretion through an unknown pathway. We aimed to ascertain the molecular mechanisms downstream of IDE, directing our efforts toward the relationship between IDE and the primary cilium. IDE was not localized to primary cilium of alpha-cells, but IDE deficiency resulted in impaired ciliogenesis. Consistent with lower levels of the insulin receptor (IR), the counterregulatory effect of insulin on glucagon secretion was reduced in IDE-deficient alpha-cells. Two cellular models of ciliary dysfunction (ARL13B-KD and IFT88-KD) resulted in impaired glucagon secretion, as well as a failure of insulin to suppress glucagon secretion in alpha-cells. Importantly, IDE, ciliary markers (AcTubulin, ARL13B) and IR levels were diminished in conditions of physiological glucagon repression. In conclusion, IDE is a mechanistic link between glucose levels and the primary cilium, which regulates glucagon secretion in alpha-cells.
2026-03-23 | PXD065342 | Pride
Project description:Aim: To investigate the compensatory role of α-cell-derived paracrine signaling through glucagon and GLP-1 receptors in maintaining β-cell function when insulin secretion is compromised. Methods: A β-cell-specific Nox4 knockout mouse (Nox4βKO), which displays defective glucose-stimulated insulin secretion, was used to assess adaptive changes in pancreatic islets. We analyzed islet composition, hormone secretion dynamics, receptor expression profiles, and downstream signaling pathways. Methodologies included immunocytochemistry, flow cytometry, RNA sequencing, cAMP assays, and functional insulin/glucagon secretion assays using both isolated islets and pancreatic slices across different glucose levels and receptor-modulating conditions. Results: Prediabetic Nox4βKO islets showed increased α-cell numbers, expansion of bihormonal cells, and elevated production of glucagon and GLP-1. Receptor profiling revealed a shift in receptor usage: whereas GLP-1R dominated in wild-type islets, GCGR signaling gained prominence in Nox4βKO islets. This restructuring appears to reflect an adaptive response to emerging β-cell dysfunction. Functional assays demonstrated that insulin secretion in prediabetic islets became increasingly reliant on glucagon-driven activation of GLP-1R and cAMP-dependent pathways. Transcriptomic and signaling data confirmed enhanced expression of cAMP-related intermediates and calcium-handling components, indicating partial preservation of insulin secretory capacity despite underlying defects. Conclusion: α-cell remodeling and flexible engagement of glucagon and GLP-1 receptors act as key compensatory mechanisms that help maintain insulin secretion during early β-cell stress. The context-dependent reordering of intra-islet receptor dominance highlights a coordinated multicellular adaptation in prediabetes and suggests that targeting intra-islet endocrine crosstalk may help preserve β-cell function in prediabetes and early type 2 diabetes.
2026-05-15 | GSE319574 | 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: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:Postoperative insulin resistance refers to the phenomenon that the body’s glucose uptake stimulated by insulin is reduced due to stress effects such as trauma or the inhibitory effect of insulin on liver glucose output is weakened after surgery.
There is a clear link between postoperative insulin resistance and poor perioperative prognosis. Therefore, exploring interventions to reduce postoperative stress insulin resistance, stabilize postoperative blood glucose, and reduce postoperative complications are clinical problems that need to be solved urgently. In recent years, research on branched-chain amino acids and metabolic diseases has become a hot spot. Studies have found that in the rat model, preoperatively given a high branched-chain amino acid diet can inhibit postoperative insulin resistance and stabilize blood glucose levels. This research plan is to try to add branched-chain amino acids before surgery to observe the occurrence of postoperative insulin resistance in patients.
| 2744698 | ecrin-mdr-crc
Project description:Dysregulated α-cell function contributes to the onset and progression of diabetes. Here, we report that the treatment with imeglimin, an anti-diabetes drug, prevents glucagon release and promotes α-to-β cell transdifferentiation through direct action on α-cells. Mechanistically, imeglimin reduces Gsα expression to attenuate EPAC2-mediated glucagon secretion induced by glucose or GIP in an insulin-independent fashion. MafB expression is downregulated by imeglimin to make α-cell transdifferentiate to β-cell. Imeglimin also upregulates CHOP expression, which partly contributes to the reduction in both Gsα and MafB expression to reduce glucagon secretion and induce α-cell dedifferentiation, without alteration of protein translation. Those pleiotropic effects of imeglimin on glucagon secretion and α-cell identity can be recapitulated by mouse models of diabetes in vivo. These data implicate the imeglimin-mediated regulation of α-cell plasticity as a novel component in diabetes therapy to correct islet functions.
2025-07-29 | GSE255447 | GEO
Project description:Appropriate glucagon secretion from pancreatic alpha cells in response to hypoglycemia is an important component of maintaining glucose homeostasis. Dysregulated glucagon secretion leads to the delayed recovery from a hypoglycemic attack in type 1 diabetes patients which can be lethal. Although elucidating the precise mechanism of glucagon secretion in hypoglycemia is warranted, the underlying mechanism remains poorly understood.The present study provides evidence of the role of autophagy in glucagon secretion in hypoglycemia by demonstrating that autophagy regulates adrenergic stimulation of glucagon secretion downstream of beta2 adrenergic receptor. First, from the analyses of T1D human islets and the published database of scRNA-seq of T1D human alpha cells, we described autophagy pathways altered in T1D alpha cells. Second, we generated alpha cell-specific Atg7KO mice (alphaAtg7KO) and clarified that the lack of autophagy in alpha cells impairs the reactive glucagon secretion in acute hypoglycemia. Third, to interrogate the molecular mechanism of autophagy-mediated glucagon regulation, we analyzed top genes downregulated inT1D and T2D alpha cells and found the expression of beta2 adrenergic receptor showed significant down-regulation in T1D alpha cells. We confirmed the decreased expression of beta2 adrenergic receptor in alpha cells of the T1D pancreas section, the islets of alphaAtg7KO mice, and a murine alpha cell line with stable knockdown of Atg7. Furthermore, in vivo and ex vivo studies of alphaAtg7KO mice exhibited that lack of autophagy led to the loss of stimulatory effect of beta2-adrenergic signaling on glucagon secretion. Finally, we established the Atg7 knockdown model in sorted human alpha cells and confirmed the effect of autophagy on the expression of the beta2 adrenergic receptor. Together, our study provides novel insights into the regulatory role of autophagy in glucagon secretion in response to hypoglycemia and provides therapeutic options to achieve stable glycemic control in T1D patients.
2024-03-31 | GSE171352 | 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