Mus musculus
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ABSTRACT:
PROVIDER: PRJNA352756 | ENA |
REPOSITORIES: ENA
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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: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: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:Pancreas volume or mass varies more than 3-fold among adult humans. The heterogeneity is likely the result of genetics, diseases, and nutrition. Dietary protein intake and blood amino acid levels are known to affect pancreas mass, but the underlying mechanism is not well understood. The goal of this study is to determine how increased blood amino acid level (hyperaminoacidemia) induces pancreas expansion.Multiple complementary mouse and zebrafish models were used to study the impact of hyperaminoacidemia on pancreatic mass, acinar cell size and proliferation. Blood amino acid levels were manipulated by dietary protein content, or by pharmacologic or genetic interruption of glucagon signaling (IGS). The activation of mammalian target of rapamycin complex 1 (mTORC1) and Yes-associated protein 1 (YAP) were determined by pS6 and YAP staining. Sirolimus administration in mice and knockdown of solute carrier family 38 member 5b (slc38a5b) and yap/taz in zebrafish were used to determine the role of mTORC1, SLC38A5 and YAP/TAZ in acinar cell proliferation and pancreas expansion. We found that the IGS-induced pancreas expansion was the result of acinar cell proliferation and hypertrophy. Hyperaminoacidemia was the likely mediator as pancreas expansion was blunted by a low protein diet in mice and by knocking down the most highly expressed amino acid transporter gene, slc38a5b, in zebrafish lacking both glucagon receptor genes (gcgr-/-). In GCGR-Ab treated mice, inhibition of mTORC1 attenuated both hyperplasia and hypertrophy of acinar cells. There was a gene expression signature of YAP activation in acinar cells, consistent with increased YAP-expressing acinar cells in GCGR-Ab treated mice and increased fraction of acinar cells with nuclear YAP1 in gcgr-/- zebrafish. Knocking down yap1 or taz decreased mTORC1 activity and acinar cell hyperplasia and hypertrophy in gcgr-/- zebrafish. Hyperaminoacidemia leads to acinar cell proliferation and hypertrophy via activation of both mTORC1 and YAP pathways. The study discovered a previously unrecognized role of the YAP/Taz pathway in hyperaminoacidemia-induced acinar cell hypertrophy and hyperplasia.
2024-03-30 | GSE243695 | GEO
Project description:Glucagon receptor (GCGR) is a potential target for diabetes therapy. Several emerging GCGR antagonism-based therapies are under pre-clinical and clinical development. However, the GCGR antagonism as well as GCGR deficient animal accompanied with α-cell hyperplasia and hyperglucagonemia, which may limit the application of GCGR antagonism. To better understand the physiological changes in the α cells during the GCGR disruption, we performed the single cell sequencing of α cells isolated from control and gcgr-/- zebrafish. We found that α cells in gcgr-/- zebrafish dramatically increased glucagon (both gcga and gcgb) expression, we also found that several transcriptional factors that regulate glucagon expression were also increased. Based on the sequencing data, we further experimentally confirmed that gcgr-/- up-regulated glucagon mRNA level by in situ hybridization, and the gcgr-/- increased glucagon promoter activity indicated by reporter line Tg(gcga: GFP). Moreover, our results also revealed that α cells increased glucagon granule population and glucagon level in gcgr-/- zebrafish. These data suggested that hyperglucagonemia in the organism of GCGR antagonism not only contributed by the α-cell hyperplasia but also contributed by the increased glucagon expression and secretion from α cells. Our study provided more comprehensive understanding of physiological changes of α-cell during the GCGR disruption.
2022-10-26 | GSE179894 | GEO
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: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: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: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