Dataset Information

GLP-1 receptor signalling promotes ?-cell glucose metabolism via mTOR-dependent HIF-1? activation.

ABSTRACT: Glucagon-like peptide-1 (GLP-1) promotes insulin secretion from pancreatic ?-cells in a glucose dependent manner. Several pathways mediate this action by rapid, kinase phosphorylation-dependent, but gene expression-independent mechanisms. Since GLP-1-induced insulin secretion requires glucose metabolism, we aimed to address the hypothesis that GLP-1 receptor (GLP-1R) signalling can modulate glucose uptake and utilization in ?-cells. We have assessed various metabolic parameters after short and long exposure of clonal BRIN-BD11 ?-cells and rodent islets to the GLP-1R agonist Exendin-4 (50?nM). Here we report for the first time that prolonged stimulation of the GLP-1R for 18?hours promotes metabolic reprogramming of ?-cells. This is evidenced by up-regulation of glycolytic enzyme expression, increased rates of glucose uptake and consumption, as well as augmented ATP content, insulin secretion and glycolytic flux after removal of Exendin-4. In our model, depletion of Hypoxia-Inducible Factor 1 alpha (HIF-1?) impaired the effects of Exendin-4 on glucose metabolism, while pharmacological inhibition of Phosphoinositide 3-kinase (PI3K) or mTOR completely abolished such effects. Considering the central role of glucose catabolism for stimulus-secretion coupling in ?-cells, our findings suggest that chronic GLP-1 actions on insulin secretion include elevated ?-cell glucose metabolism. Moreover, our data reveal novel aspects of GLP-1 stimulated insulin secretion involving de novo gene expression.

SUBMITTER: Carlessi R

PROVIDER: S-EPMC5454020 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

GLP-1 receptor signalling promotes β-cell glucose metabolism via mTOR-dependent HIF-1α activation.

Carlessi Rodrigo R Chen Younan Y Rowlands Jordan J Cruzat Vinicius F VF Keane Kevin N KN Egan Lauren L Mamotte Cyril C Stokes Rebecca R Gunton Jenny E JE Bittencourt Paulo Ivo Homem de PIH Newsholme Philip P

Scientific reports 20170601 1

Glucagon-like peptide-1 (GLP-1) promotes insulin secretion from pancreatic β-cells in a glucose dependent manner. Several pathways mediate this action by rapid, kinase phosphorylation-dependent, but gene expression-independent mechanisms. Since GLP-1-induced insulin secretion requires glucose metabolism, we aimed to address the hypothesis that GLP-1 receptor (GLP-1R) signalling can modulate glucose uptake and utilization in β-cells. We have assessed various metabolic parameters after short and l ...[more]

PMID: 28572610

Similar Datasets

Project description:BackgroundEpithelial-mesenchymal transition (EMT) of mesothelial cells is a key step in the peritoneal fibrosis (PF). Recent evidence indicates that signal transducer and activator of transcription 3 (STAT3) might mediate the process of renal fibrosis, which could induce the expression of hypoxia-inducible factor-1α (HIF-1α). Here, we investigated the effect of STAT3 activation on HIF-1α expression and the EMT of mesothelial cells, furthermore the role of pharmacological blockade of STAT3 in the process of PF during peritoneal dialysis (PD) treatment.MethodsFirstly, we investigated the STAT3 signaling in human peritoneal mesothelial cells (HPMCs) from drained PD effluent. Secondly, we explored the effect of STAT3 signaling activation on the EMT and the expression of HIF-1α in human mesothelial cells (Met-5A) induced by high glucose. Finally, peritoneal fibrosis was induced by daily intraperitoneal injection with peritoneal dialysis fluid (PDF) so as to explore the role of pharmacological blockade of STAT3 in this process.ResultsCompared with the new PD patient, the level of phosphorylated STAT3 was up-regulated in peritoneal mesothelial cells from long-term PD patients. High glucose (60 mmol/L) induced over-expression of Collagen I, Fibronectin, α-SMA and reduced the expression of E-cadherin in Met-5A cells, which could be abrogated by STAT3 inhibitor S3I-201 pretreatment as well as by siRNA for STAT3. Furthermore, high glucose-mediated STAT3 activation in mesothelial cells induced the expression of HIF-1α and the profibrotic effect of STAT3 signaling was alleviated by siRNA for HIF-1α. Daily intraperitoneal injection of high-glucose based dialysis fluid (HG-PDF) induced peritoneal fibrosis in the mice, accompanied by the phosphorylation of STAT3. Immunostaining showed that phosphorylated STAT3 was expressed mostly in α-SMA positive cells in the peritoneal membrane induced by HG-PDF. Administration of S3I-201 prevented the progression of peritoneal fibrosis, angiogenesis, macrophage infiltration as well as the expression of HIF-1α in the peritoneal membrane induced by high glucose.ConclusionsTaken together, these findings identified a novel mechanism linking STAT3/HIF-1α signaling to peritoneal fibrosis during long-term PD treatment. It provided the first evidence that pharmacological inhibition of STAT3 signaling attenuated high glucose-mediated mesothelial cells EMT as well as peritoneal fibrosis.

Project description:Background: The management of aggressive and progressive metastatic papillary thyroid cancer (PTC) is very difficult. An inverse relationship between radioiodine and F-18 fluorodeoxyglucose (FDG) uptake (''flip-flop'' phenomenon) is described for invasive PTC during dedifferentiation. However, no satisfactory biologic explanation for this phenomenon. Hypoxia is an important microenvironmental factor that promotes cancer progression and glycolysis. The Hippo-YAP is a highly conserved tumor suppressor pathway and contributes to cancer metabolic reprogramming. Thus, we investigated the underlying molecular mechanisms of glucose/iodine metabolic reprogramming in PTC, focusing on the tumor hypoxia microenvironment and Hippo-YAP signaling. Methods: Immunohistochemistry staining was conducted to evaluate the expressions of hypoxia-inducible factor 1α (HIF-1α), yes-associated protein (YAP), glucose transporters 1 (GLUT1) and sodium iodine symporter (NIS) in matched PTC and the adjacent noncancerous tissues. PTC cell lines were cultured under normoxic (20% O2) and hypoxic (1% O2) conditions and the glycolysis level and NIS expression were measured. Further, we characterized the molecular mechanism of glucose/iodine metabolic reprogramming in PTC cell. Finally, we validated the results in vivo by establishing subcutaneous xenografts in nude mice. Results: The expression levels of HIF1-α, YAP and GLUT1 were upregulated in PTC tissues and YAP expression was positively associated with HIF-1α, GLUT1 and TNM stages. Meanwhile, the expression of NIS was negatively correlated with YAP. Further, in vitro studies indicated that hypoxia-induced YAP activation was critical for accelerating glycolysis and reducing NIS expression in PTC cells. Inhibition of YAP had the opposite effects in vitro and tumorigenicity in vivo. Hypoxia inhibited the Hippo signaling pathway resulting in the inactivation of YAP phosphorylation, further promoting the nuclear localization of YAP in PTC cells. The mechanism is that hypoxic stress promoted YAP binding to HIF-1α in the nucleus and maintained HIF-1α protein stability. The YAP/HIF-1α complex bound and directly activated the GLUT1 transcription to accelerate glycolysis. Meanwhile, HIF-1α/YAP signaling might indirectly reduce the expression of NIS by promoting the output of MAPK signaling. In vivo studies confirmed the YAP-mediated reprogramming of glucose/iodine metabolism promoted PTC progression. Conclusions: Collectively, our data revealed a novel regulatory mechanism of the glucose/iodine metabolic program rewritten by HIF-1α/YAP signaling in PTC. Inhibition of HIF-1α/YAP signaling alone or in combination with other potential markers may effectively combat aggressive PTC.

Dataset Information

GLP-1 receptor signalling promotes ?-cell glucose metabolism via mTOR-dependent HIF-1? activation.

Publications

GLP-1 receptor signalling promotes β-cell glucose metabolism via mTOR-dependent HIF-1α activation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets