scholarly journals Glucagon and lipid interactions in the regulation of hepatic AMPK signaling and expression of PPARα and FGF21 transcripts in vivo

2010 ◽  
Vol 299 (4) ◽  
pp. E607-E614 ◽  
Author(s):  
Eric D. Berglund ◽  
Li Kang ◽  
Robert S. Lee-Young ◽  
Clinton M. Hasenour ◽  
Daniel G. Lustig ◽  
...  
Keyword(s):  
Whole Body ◽  
Fibroblast Growth Factor 21 ◽  
Peroxisome Proliferator ◽  
Glucagon Receptor ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ampk Signaling ◽  
Downstream Target ◽  
Amp Activated Protein Kinase ◽  
Fgf21 Expression

Hepatic glucagon action increases in response to accelerated metabolic demands and is associated with increased whole body substrate availability, including circulating lipids. The hypothesis that increases in hepatic glucagon action stimulate AMP-activated protein kinase (AMPK) signaling and peroxisome proliferator-activated receptor-α (PPARα) and fibroblast growth factor 21 (FGF21) expression in a manner modulated by fatty acids was tested in vivo. Wild-type ( gcgr+/+) and glucagon receptor-null ( gcgr−/−) littermate mice were studied using an 18-h fast, exercise, and hyperglucagonemic-euglycemic clamps plus or minus increased circulating lipids. Fasting and exercise in gcgr+/+, but not gcgr−/− mice, increased hepatic phosphorylated AMPKα at threonine 172 (p-AMPKThr172) and PPARα and FGF21 mRNA. Clamp results in gcgr+/+ mice demonstrate that hyperlipidemia does not independently impact or modify glucagon-stimulated increases in hepatic AMP/ATP, p-AMPKThr172, or PPARα and FGF21 mRNA. It blunted glucagon-stimulated acetyl-CoA carboxylase phosphorylation, a downstream target of AMPK, and accentuated PPARα and FGF21 expression. All effects were absent in gcgr−/− mice. These findings demonstrate that glucagon exerts a critical regulatory role in liver to stimulate pathways linked to lipid metabolism in vivo and shows for the first time that effects of glucagon on PPARα and FGF21 expression are amplified by a physiological increase in circulating lipids.

scholarly journals In Vivo Analysis of miR-34a Regulated Glucose Metabolism Related Genes in Megalobrama amblycephala

2018 ◽  
Vol 19 (8) ◽  
pp. 2417 ◽  
Author(s):  
Ling-Hong Miao ◽  
Yan Lin ◽  
Xin Huang ◽  
Wen-Jing Pan ◽  
Qun-Lan Zhou ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Target Genes ◽  
Enrichment Analysis ◽  
Janus Kinase ◽  
Megalobrama Amblycephala ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ampk Signaling ◽  
Downstream Target

The Megalobrama amblycephala (M. amblycephala) is one of the most important economic freshwater fish in China. The molecular mechanism under the glucose intolerance responses which affects the growth performance and feed utilization is still confused. miR-34a was reported as a key regulator in the glucose metabolism, but how did the miR-34a exert its function in the metabolism of glucose/insulin in M. amblycephala was still unclear. In this study, we intraperitoneally injected the miR-34a inhibitor (80 nmol/100 g body weight) into M. amblycephala (fed with high starch diet, 45% starch) for 12 h, and then analyzed the gene expression profiling in livers by RNA-seq. The results showed that miR-34a expression in M. amblycephala livers was inhibited by injection of miR-34a inhibitor, and a total of 2212 differentially expressed genes (DEGs) were dysregulated (including 1183 up- and 1029 downregulated DEGs). Function enrichment analysis of DEGs showed that most of them were enriched in the peroxisome proliferator-activated receptor (PPAR), insulin, AMP-activated protein kinase (AMPK) and janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathways, which were all associated with the glucose/lipid metabolic and biosynthetic processes. In addition, we examined and verified the differential expression levels of some genes involved in AMPK signaling pathway by qRT-PCR. These results demonstrated that the inhibition of miR-34a might regulate glucose metabolism in M. amblycephala through downstream target genes.

scholarly journals Glucocorticoids Regulate the Metabolic Hormone FGF21 in a Feed-Forward Loop

2015 ◽  
Vol 29 (2) ◽  
pp. 213-223 ◽  
Author(s):  
Rucha Patel ◽  
Angie L. Bookout ◽  
Lilia Magomedova ◽  
Bryn M. Owen ◽  
Giulia P. Consiglio ◽  
...  
Keyword(s):  
Primary Cultures ◽  
Fibroblast Growth Factor 21 ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Peroxisome Proliferator Activated Receptor ◽  
Feed Forward ◽  
Feed Forward Loop ◽  
Corticosterone Secretion ◽  
Fgf21 Expression

Abstract Hormones such as fibroblast growth factor 21 (FGF21) and glucocorticoids (GCs) play crucial roles in coordinating the adaptive starvation response. Here we examine the interplay between these hormones. It was previously shown that FGF21 induces corticosterone levels in mice by acting on the brain. We now show that this induces the expression of genes required for GC synthesis in the adrenal gland. FGF21 also increases corticosterone secretion from the adrenal in response to ACTH. We further show that the relationship between FGF21 and GCs is bidirectional. GCs induce Fgf21 expression in the liver by acting on the GC receptor (GR). The GR binds in a ligand-dependent manner to a noncanonical GR response element located approximately 4.4 kb upstream of the Fgf21 transcription start site. The GR cooperates with the nuclear fatty acid receptor, peroxisome proliferator-activated receptor-α, to stimulate Fgf21 transcription. GR and peroxisome proliferator-activated receptor-α ligands have additive effects on Fgf21 expression both in vivo and in primary cultures of mouse hepatocytes. We conclude that FGF21 and GCs regulate each other's production in a feed-forward loop and suggest that this provides a mechanism for bypassing negative feedback on the hypothalamic-pituitary-adrenal axis to allow sustained gluconeogenesis during starvation.

PGC-1α is required for AICAR-induced expression of GLUT4 and mitochondrial proteins in mouse skeletal muscle

2010 ◽  
Vol 299 (3) ◽  
pp. E456-E465 ◽  
Author(s):  
Lotte Leick ◽  
Joachim Fentz ◽  
Rasmus S. Biensø ◽  
Jakob G. Knudsen ◽  
Jacob Jeppesen ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Whole Body ◽  
Peroxisome Proliferator ◽  
Hexokinase Ii ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ampk Signaling ◽  
Downstream Target ◽  
Mrna Content ◽  
Cyt C

We tested the hypothesis that repeated activation of AMP-activated protein kinase (AMPK) induces mitochondrial and glucose membrane transporter mRNA/protein expression via a peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α)-dependent mechanism. Whole body PGC-1α-knockout (KO) and littermate wild-type (WT) mice were given either single or repeated subcutaneous injections of the AMPK activator AICAR or saline. Skeletal muscles were removed either 1 or 4 h after the single AICAR treatment or 24 h after the last injection following repeated AICAR treatment. Repeated AICAR treatment increased GLUT4, cytochrome (cyt) c oxidase I, and (cyt) c protein expression ∼10–40% relative to saline in white muscles of WT but not of PGC-1α-KO mice, whereas fatty acid translocase/CD36 (FAT/CD36) protein expression was unaffected by AICAR treatment in both genotypes. GLUT4, cyt c, and FAT/CD36 mRNA content increased 30–60% 4 h after a single AICAR injection relative to saline in WT, and FAT/CD36 mRNA content decreased in PGC-1α-KO mice. One hour after a single AICAR treatment, phosphorylation of AMPK and the downstream target acetyl-coenzyme A carboxylase increased in all muscles investigated independent of genotype, indicating normal AICAR-induced AMPK signaling in the absence of PGC-1α. The hexokinase II (HKII) mRNA and protein response was similar in muscles of WT and PGC-1α-KO mice after single and repeated AICAR treatments, respectively, confirming that HKII is regulated independently of PGC-1α in response to AICAR. In conclusion, here we provide genetic evidence for a role of PGC-1α in AMPK-mediated regulation of mitochondrial and glucose membrane transport protein expression in skeletal muscle.

scholarly journals Adipocyte PHLPP2 inhibition prevents obesity-induced fatty liver

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
KyeongJin Kim ◽  
Jin Ku Kang ◽  
Young Hoon Jung ◽  
Sang Bae Lee ◽  
Raffaela Rametta ◽  
...  
Keyword(s):  
Fatty Liver ◽  
Whole Body ◽  
Acid Oxidation ◽  
Chow Diet ◽  
Peroxisome Proliferator ◽  
Obese Mice ◽  
Ph Domain ◽  
Peroxisome Proliferator Activated Receptor

AbstractIncreased adiposity confers risk for systemic insulin resistance and type 2 diabetes (T2D), but mechanisms underlying this pathogenic inter-organ crosstalk are incompletely understood. We find PHLPP2 (PH domain and leucine rich repeat protein phosphatase 2), recently identified as the Akt Ser473 phosphatase, to be increased in adipocytes from obese mice. To identify the functional consequence of increased adipocyte PHLPP2 in obese mice, we generated adipocyte-specific PHLPP2 knockout (A-PHLPP2) mice. A-PHLPP2 mice show normal adiposity and glucose metabolism when fed a normal chow diet, but reduced adiposity and improved whole-body glucose tolerance as compared to Cre- controls with high-fat diet (HFD) feeding. Notably, HFD-fed A-PHLPP2 mice show increased HSL phosphorylation, leading to increased lipolysis in vitro and in vivo. Mobilized adipocyte fatty acids are oxidized, leading to increased peroxisome proliferator-activated receptor alpha (PPARα)-dependent adiponectin secretion, which in turn increases hepatic fatty acid oxidation to ameliorate obesity-induced fatty liver. Consistently, adipose PHLPP2 expression is negatively correlated with serum adiponectin levels in obese humans. Overall, these data implicate an adipocyte PHLPP2-HSL-PPARα signaling axis to regulate systemic glucose and lipid homeostasis, and suggest that excess adipocyte PHLPP2 explains decreased adiponectin secretion and downstream metabolic consequence in obesity.

scholarly journals High Sugar Intake and Development of Skeletal Muscle Insulin Resistance and Inflammation in Mice: A Protective Role for PPAR-δAgonism

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Elisa Benetti ◽  
Raffaella Mastrocola ◽  
Mara Rogazzo ◽  
Fausto Chiazza ◽  
Manuela Aragno ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Signaling Pathways ◽  
Gastrocnemius Muscle ◽  
Metabolic Diseases ◽  
Whole Body ◽  
Intercellular Adhesion Molecule ◽  
Fibroblast Growth Factor 21 ◽  
Peroxisome Proliferator ◽  
Intercellular Adhesion Molecule 1 ◽  
Peroxisome Proliferator Activated Receptor

Peroxisome Proliferator Activated Receptor (PPAR)-δagonists may serve for treating metabolic diseases. However, the effects of PPAR-δagonism within the skeletal muscle, which plays a key role in whole-body glucose metabolism, remain unclear. This study aimed to investigate the signaling pathways activated in the gastrocnemius muscle by chronic administration of the selective PPAR-δagonist, GW0742 (1 mg/kg/day for 16 weeks), in male C57Bl6/J mice treated for 30 weeks with high-fructose corn syrup (HFCS), the major sweetener in foods and soft-drinks (15% wt/vol in drinking water). Mice fed with the HFCS diet exhibited hyperlipidemia, hyperinsulinemia, hyperleptinemia, and hypoadiponectinemia. In the gastrocnemius muscle, HFCS impaired insulin and AMP-activated protein kinase signaling pathways and reduced GLUT-4 and GLUT-5 expression and membrane translocation. GW0742 administration induced PPAR-δupregulation and improvement in glucose and lipid metabolism. Diet-induced activation of nuclear factor-κB and expression of inducible-nitric-oxide-synthase and intercellular-adhesion-molecule-1 were attenuated by drug treatment. These effects were accompanied by reduction in the serum concentration of interleukin-6 and increase in muscular expression of fibroblast growth factor-21. Overall, here we show that PPAR-δactivation protects the skeletal muscle against the metabolic abnormalities caused by chronic HFCS exposure by affecting multiple levels of the insulin and inflammatory cascades.

scholarly journals Hyperthyroidism Evokes Myocardial Ceramide Accumulation

2015 ◽  
Vol 35 (2) ◽  
pp. 755-766 ◽  
Author(s):  
Agnieszka Mikłosz ◽  
Bartłomiej Łukaszuk ◽  
Adrian Chabowski ◽  
Filip Rogowski ◽  
Krzysztof Kurek ◽  
...  
Keyword(s):  
Peroxisome Proliferator ◽  
Cardiac Physiology ◽  
Peroxisome Proliferator Activated Receptor ◽  
Sphingosine 1 Phosphate ◽  
Male Wistar Rats ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Cpt I ◽  
Amp Activated Protein Kinase ◽  
Ceramide Accumulation

Background: Thyroid hormones (THs) are key regulators of cardiac physiology as well as modulators of different cellular signals including the sphingomyelin/ceramide pathway. The objective of this study was to examine the effect of hyperthyroidism on the metabolism of sphingolipids in the muscle heart. Methods: Male Wistar rats were treated for 10 days with triiodothyronine (T3) at a dose of 50µg/100g of body weight. Animals were then anaesthetized and samples of the left ventricle were excised. Results: We have demonstrated that prolonged, in vivo, T3 treatment increased the content of sphinganine (SFA), sphingosine (SFO), ceramide (CER) and sphingomyelin (SM), but decreased the level of sphingosine-1-phosphate (S1P) in cardiac muscle. Accordingly, the changes in sphingolipids content were accompanied by a lesser activity of neutral sphingomyelinase and without significant changes in ceramidases activity. Hyperthyroidism also induced activation of AMP-activated protein kinase (AMPK) with subsequently increased expression of mitochondrial proteins: cytochrome c oxidase IV (COX IV), β-hydroxyacyl-CoA dehydrogenase (β-HAD), carnityne palmitoyltransferase I (CPT I) and nuclear peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α). Conclusions: We conclude that prolonged T3 treatment increases sphingolipids metabolism which is reflected by higher concentration of SFA and CER in heart muscle. Furthermore, hyperthyroidism-induced increase in heart sphingomyelin (SM) concentration might be one of the mechanisms underlying maintenance of CER at relatively low level by its conversion to SM together with decreased S1P content.

Chronic rosiglitazone treatment restores AMPKα2 activity in insulin-resistant rat skeletal muscle

2006 ◽  
Vol 290 (2) ◽  
pp. E251-E257 ◽  
Author(s):  
Sarah J. Lessard ◽  
Zhi-Ping Chen ◽  
Matthew J. Watt ◽  
Michael Hashem ◽  
Julianne J. Reid ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Zucker Rats ◽  
Control Group ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ampk Signaling ◽  
Palmitate Oxidation ◽  
Insulin Resistant ◽  
Obese Zucker Rats

Rosiglitazone (RSG) is an insulin-sensitizing thiazolidinedione (TZD) that exerts peroxisome proliferator-activated receptor-γ (PPARγ)-dependent and -independent effects. We tested the hypothesis that part of the insulin-sensitizing effect of RSG is mediated through the action of AMP-activated protein kinase (AMPK). First, we determined the effect of acute (30–60 min) incubation of L6 myotubes with RSG on AMPK regulation and palmitate oxidation. Compared with control (DMSO), 200 μM RSG increased ( P < 0.05) AMPKα1 activity and phosphorylation of AMPK (Thr172). In addition, acetyl-CoA carboxylase (Ser218) phosphorylation and palmitate oxidation were increased ( P < 0.05) in these cells. To investigate the effects of chronic RSG treatment on AMPK regulation in skeletal muscle in vivo, obese Zucker rats were randomly allocated into two experimental groups: control and RSG. Lean Zucker rats were treated with vehicle and acted as a control group for obese Zucker rats. Rats were dosed daily for 6 wk with either vehicle (0.5% carboxymethylcellulose, 100 μl/100 g body mass), or 3 mg/kg RSG. AMPKα1 activity was similar in muscle from lean and obese animals and was unaffected by RSG treatment. AMPKα2 activity was ∼25% lower in obese vs. lean animals ( P < 0.05) but was normalized to control values after RSG treatment. ACC phosphorylation was decreased with obesity ( P < 0.05) but restored to the level of lean controls with RSG treatment. Our data demonstrate that RSG restores AMPK signaling in skeletal muscle of insulin-resistant obese Zucker rats.

scholarly journals Tfe3 and Tfeb Transcriptionally Regulate Peroxisome Proliferator-Activated Receptor γ2 Expression in Adipocytes and Mediate Adiponectin and Glucose Levels in Mice

2017 ◽  
Vol 37 (15) ◽  
Author(s):  
Nunciada Salma ◽  
Jun S. Song ◽  
Akinori Kawakami ◽  
Suprabha P. Devi ◽  
Mehdi Khaled ◽  
...  
Keyword(s):  
Transcriptional Control ◽  
Regulatory Region ◽  
Whole Body ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Fed State ◽  
Glucose Levels ◽  
E Boxes

ABSTRACT Members of the MiT transcription factor family are pivotal regulators of several lineage-selective differentiation programs. We show that two of these, Tfeb and Tfe3, control the regulator of adipogenesis, peroxisome proliferator-activated receptor γ2 (Pparγ2). Knockdown of Tfeb or Tfe3 expression during in vitro adipogenesis causes dramatic downregulation of Pparγ2 expression as well as adipogenesis. Additionally, we found that these factors regulate Pparγ2 in mature adipocytes. Next, we demonstrated that Tfeb and Tfe3 act directly by binding to consensus E-boxes within the Pparγ transcriptional regulatory region. This transcriptional control also exists in vivo, as we discovered that wild-type mice in the fed state increased their expression of Tfe3, Tf3b, and Pparγ in white adipose tissue. Furthermore, Tfe3 knockout (Tfe3KO) mice in the fed state failed to upregulate Pparγ and the adiponectin gene, a Pparγ-dependent gene, confirming the in vivo role for Tfe3. Lastly, we found that blood glucose is elevated and serum adiponectin levels are suppressed in the Tfe3KO mice, indicating that the Tfe3/Tfeb/Pparγ2 axis may contribute to whole-body energy balance. Thus, we offer new insights into the upstream regulation of Pparγ by Tfe3/Tf3b and propose that targeting these transcription factors may offer opportunities to complement existing approaches for the treatment of diseases that have dysregulated energy metabolism.

scholarly journals Effect of taurine intervention on oleic acid-induced primary hepatocyte steatosis in orange-spotted grouper (Epinephelus coioides)

2021 ◽  
pp. 43-43
Author(s):  
Ruyi Xiao ◽  
Hanmo Feng ◽  
Xingjian Niu ◽  
Fakai Bai ◽  
Jidan Ye
Keyword(s):  
Oleic Acid ◽  
Fatty Acid ◽  
Peroxisome Proliferator ◽  
Epinephelus Coioides ◽  
High Fat ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ampk Signaling ◽  
Hepatocyte Steatosis ◽  
Amp Activated Protein Kinase ◽  
First Time

Examination of the molecular mechanism of taurine regulation of lipid metabolism in fish is limited. In this study, an oleic acid (OA)-induced hepatocyte steatosis model of orange-spotted grouper (Epinephelus coioides) was established for the first time. The model was used to test the effect of taurine on steatosis hepatocytes in Control, High-fat (0.4 mM OA) and Taurine (0.4 mM OA + 2 mM taurine) experimental groups of fish. Hepatocyte samples were subjected to transcriptome analysis. A total of 99634 unigenes was assembled, 69982 unigenes were annotated and 1831 differentially expressed genes (DEGs) in Control vs High-fat group, and 526 DEGs in the High-fat vs Taurine group were identified, of which 824 DEGs (Control vs High-fat) and 237 DEGs (High-fat vs Taurine) were observed to be upregulated, and 1007 DEGs (Control vs High-fat) and 289 DEGs (High-fat vs Taurine) were downregulated after taurine intervention. These genes are involved in peroxisome proliferator-activated receptor (PPAR) and 5' AMP-activated protein kinase (AMPK) signaling pathways, fatty acid elongation, primary bile acid biosynthesis, glycerophospholipid and glycerolipid metabolism. The findings provide new clues in understanding the regulatory role of taurine in lipid and fatty acid metabolism of fish. It is hoped that the obtained results will help in the design of feed formulations to improve grouper growth from the perspective of aquaculture nutrition.

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