Project description:A greater understanding of the glucose homeostasis mediated by glucagon-like peptide-1 (GLP-1) will facilitate the development of novel glucose-lowering treatments. Here we show that improved glucose metabolism in hypothyroid mice after treatment of T3, the active form of thyroid hormone (TH), is accompanied with increased GLP-1 production and insulin secretion. Treatment of a GLP-1 receptor antagonist is able to attenuate the observed T3 effect on insulin and glucose levels, suggesting that GLP-1 is critically involved in the regulation of glucose homeostasis by T3. By using a mouse model lacking hepatic TH receptor β (TRβ) and a liver-specific TRβ-selective agonist, we demonstrate that TRβ-mediated hepatic TH signalling is not only required for the regulation of GLP-1 production by T3 but also the insulinotropic and glucose-lowering effects of T3. Accordingly, administration of the liver-targeted TRβ-selective agonist is capable of increasing GLP-1 and insulin levels and alleviating hyperglycemia in diet-induced obesity. Mechanistically, through suppressing CYP8B1 expression, T3 shapes the bile acid (BA) composition and increases the levels of Farnesoid X receptor (FXR)-antagonistic BAs, thereby potentiating the GLP-1 production and insulin secretion by repressing intestinal FXR signalling. Consistently, correlations between the T3 levels and either GLP-1 or FXR-antagonistic BA levels can be observed in euthyroid human subjects. Thus, our study reveals a previously undescribed role of hepatic TH signalling in glucose homeostasis through the regulation of GLP-1 production via BA-mediated FXR antagonism, which will underpin the development of novel therapeutics.
Project description:A greater understanding of the glucose homeostasis mediated by glucagon-like peptide-1 (GLP-1) will facilitate the development of novel glucose-lowering treatments. Here we show that improved glucose metabolism in hypothyroid mice after treatment of T3, the active form of thyroid hormone (TH), is accompanied with increased GLP-1 production and insulin secretion. Treatment of a GLP-1 receptor antagonist is able to attenuate the observed T3 effect on insulin and glucose levels, suggesting that GLP-1 is critically involved in the regulation of glucose homeostasis by T3. By using a mouse model lacking hepatic TH receptor β (TRβ) and a liver-specific TRβ-selective agonist, we demonstrate that TRβ-mediated hepatic TH signalling is not only required for the regulation of GLP-1 production by T3 but also the insulinotropic and glucose-lowering effects of T3. Accordingly, administration of the liver-targeted TRβ-selective agonist is capable of increasing GLP-1 and insulin levels and alleviating hyperglycemia in diet-induced obesity. Mechanistically, through suppressing CYP8B1 expression, T3 shapes the bile acid (BA) composition and increases the levels of Farnesoid X receptor (FXR)-antagonistic BAs, thereby potentiating the GLP-1 production and insulin secretion by repressing intestinal FXR signalling. Consistently, correlations between the T3 levels and either GLP-1 or FXR-antagonistic BA levels can be observed in euthyroid human subjects. Thus, our study reveals a previously undescribed role of hepatic TH signalling in glucose homeostasis through the regulation of GLP-1 production via BA-mediated FXR antagonism, which will underpin the development of novel therapeutics.
Project description:Illuminating the mechanisms controlling glucose homeostasis may deepen our understanding of the pathogenesis of T2DM and provide new therapeutic strategies for T2DM in future. As reported, Dyrk1b is a pleiotropic protein and its genetic mutations associate with blood glucose levels. Yet, the role of Dyrk1b in glucose metabolism is not well understood. Herein, we find that hepatic Dyrk1b overexpression in mice impairs the glucose tolerance and insulin resistance, whereas global Dyrk1b deficiency improves glucose metabolism of mcie. Dyrk1b overexpression in vitro blunts insulin signalling and glucose uptake. Collectively, our study uncovers a novel link between hepatic Dyrk1b and whole body glucose homeostasis.
Project description:Elucidation of the mechanisms controlling glucose homeostasis may deepen our understanding of the pathogenesis of T2DM and provide new therapeutic strategies for T2DM in the future. As reported, Dyrk1b is a pleiotropic protein and its genetic mutations are associated with blood glucose levels. However, the role of Dyrk1b in glucose metabolism is not well understood. Herein, we find that hepatic Dyrk1b overexpression in mice impairs the glucose tolerance and insulin resistance, whereas global Dyrk1b deficiency improves glucose metabolism of mcie. Dyrk1b overexpression in vitro blunts insulin signalling and glucose uptake. Collectively, our study uncovers a novel link between hepatic Dyrk1b and whole body glucose homeostasis.
Project description:Adropin is a multifunctional peptide hormone encoded by the ENHO (energy homeostasis associated) gene. It plays a role in mechanisms related to increased adiposity, insulin resistance, as well as glucose and lipid metabolism. The low adropin levels are strongly associated with obesity independent insulin resistance. On the other hand, overexpression or exogenous administration of adropin improves glucose homeostasis. The multidirectional, adropin-related effects associated with the regulation of metabolism in humans also appear to be attributable to the effects of this peptide on the activity of various elements of the endocrine system including adrenal cortex. Therefore, the main purpose of the present study was to investigate the effect of adropin on proliferation and secretory activity in the human HAC15 adrenal carcinoma cell line. We also found that HAC15 cells treated with adropin presented significantly higher proliferation levels than untreated cells. Based on whole transcriptome study and research involving transforming growth factor (TGF)-β type I receptor kinase inhibitor we demonstrated that attenuation of steroidogenesis caused by adropin is mediated by the TGF-β signalling pathway likely to act through transactivation mechanism.
Project description:Illuminating the mechanisms controlling glucose homeostasis may deepen our understanding of the pathogenesis of T2DM and provide new therapeutic strategies for T2DM in future. As reported, Dyrk1b is a pleiotropic protein and its genetic mutations associate with blood glucose levels. Yet, its role in glucose metabolism remains to be established. Herein, we invetigate the role of Dyrk1b in glucose metabolism and the underlying mechanisms. We find that hepatic Dyrk1b overexpression in mice impairs the glucose tolerance and insulin resistance, whereas global Dyrk1b deficiency improves glucose metabolism of mcie. Dyrk1b overexpression in vitro blunts insulin signalling and glucose uptake. Quantitative proteomic analyses further reveal that Wbp2 is a putative target of Dyrk1b. Importantly, hepatic Wbp2 restoration rescues the glucose homeostasis in Dyrk1b overexpression mice. Additionally, ATAC-seq analyses indicate Dyrk1b’s role in remodelling hepatic chromatin landscape. Collectively, our study uncovers a novel link between hepatic Dyrk1b and whole body glucose homeostasis via modulation of hepatic Wbp2 expression.
Project description:Bile acids (BAs), via the nuclear receptor FXR, regulate a complex transcriptional program to maintain fat, glucose, and protein metabolism. The mTORC1 signalling pathway integrates diverse nutrient/hormonal signals into FXR-related metabolic outputs, raising the question whether these transcriptional and posttranslational cascades are intertwined to maintain cellular homeostasis. Human HepG2 cells were treated with LXR agonist (GW3965), FXR agonist (GW4064) alone or combined with mTORC1 inhibitor Torin 1 (TOI), or combined with glucose/glutamine starved media (GLUST).
Project description:<p>TThe IRAS Family Study was a family study designed to examine the genetic and epidemiologic basis of glucose homeostasis traits and abdominal adiposity. Briefly, self-reported Mexican pedigrees were recruited in San Antonio, TX and San Luis Valley, CO. Probands with large families were recruited from the initial non-family-based IRAS Study, which was modestly enriched for impaired glucose tolerance and T2D. GUARDIAN includes 1,024 individuals in 88 pedigrees from the IRAS Family Study. Insulin sensitivity was obtained by FSIGT.</p>
Project description:NPY signalling via osteoblastic Y1 receptors has been shown to control bone mass but also contributes significantly to the control of whole-body insulin secretion and glucose homeostasis in mice through the release of novel factor(s) which are different from the previously implicated osteocalcin. We used microarrays to identify novel endocrine factors regulated by Y1 receptors and involved in the regulation of bone mass and whole-body homeostasis.
Project description:Research on the pathogenesis of diabetic nephropathy focuses on regional immune regulation, homeostasis regulation of glucose and lipid metabolism, epigenetic regulation, and immune-metabolic interactions.