Cannabinoid Receptor Type 1 (CB1R) Signaling Regulates Hepatic Gluconeogenesis via Induction of Endoplasmic Reticulum-bound Transcription Factor cAMP-responsive Element-binding Protein H (CREBH) in Primary Hepatocytes
mice; obesity; Biochemistry & Molecular Biology; risk-factors; er stress; activation; food-intake; dysregulation; endocannabinoid system; overweight patients; rimonabant
Activated cannabinoid 1 receptor (CB1R) signaling has been implicated in the development of phenotypes associated with fatty liver, insulin resistance, and impaired suppression of hepatic glucose output. Endoplasmic reticulum stress-associated liver-specific transcription factor CREBH is emerging as a critical player in various hepatic metabolic pathways and regulates hepatic gluconeogenesis in diet-induced obese settings. In this study, we elucidated the critical role of CREBH in mediating CB1R signaling to regulate glucose homeostasis in primary rat and human hepatocytes. mRNA and protein levels and glucose production were analyzed in primary rat and human hepatocytes. ChIP assays were performed together with various transcriptional analyses using standard techniques. CB1R activation by 2-arachidonoylglycerol (2-AG) specifically induced CREBH gene expression via phosphorylation of the JNK signaling pathway and c-Jun binding to the AP-1 binding site in the CREBH gene promoter. 2-AG treatment significantly induced hepatic gluconeogenic gene expression and glucose production in primary hepatocytes, and we demonstrated that the CREBH binding site mutant significantly attenuated 2-AG-mediated activation of the gluconeogenic gene promoter. Endogenous knockdown of CREBH led to ablation of 2-AG-induced gluconeogenic gene expression and glucose production, and the CB1R antagonist AM251 or insulin exhibited repression of CREBH gene induction and subsequently inhibited gluconeogenesis in both rat and human primary hepatocytes. These results demonstrate a novel mechanism of action of activated CB1R signaling to induce hepatic gluconeogenesis via direct activation of CREBH, thereby contributing to a better understanding of the endocannabinoid signaling mechanism involved in regulating the hepatic glucose metabolism.
Chanda D; Kim D K; Li T G; Kim Y H; Koo S H; Lee C H; Chiang J Y L; Choi H S
Journal of Biological Chemistry
2011
2011-08
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1074/jbc.M111.224352" target="_blank" rel="noreferrer noopener">10.1074/jbc.M111.224352</a>
Hepatic Cannabinoid Receptor Type 1 Mediates Alcohol-Induced Regulation of Bile Acid Enzyme Genes Expression Via CREBH
metabolism; Ohio; mice; Signaling; Signal transduction; liver; Homeostasis; transcription factor; Genes; exposure; Acids; er stress; endoplasmic-reticulum stress; Science & Technology - Other Topics; insulin-resistance; cholesterol 7-alpha-hydroxylase; human hepatocytes; Rodents; Bile acids; alcohol; element-binding protein; gene-expression; endocannabinoid system; bound; cb1 receptors; leptin resistance; Liver diseases; Diabetes mellitus; insulin-resistance; insulin; Fatty liver; hepatocytes; Sciences: Comprehensive Works; Alcohols; Bile; activation; Damage prevention; Deregulation; Muridae; Regulatory mechanisms (biology); RNA extraction; Synthesis
Bile acids concentration in liver is tightly regulated to prevent cell damage. Previous studies have demonstrated that deregulation of bile acid homeostasis can lead to cholestatic liver disease. Recently, we have shown that ER-bound transcription factor Crebh is a downstream effector of hepatic Cb1r signaling pathway. In this study, we have investigated the effect of alcohol exposure on hepatic bile acid homeostasis and elucidated the mediatory roles of Cb1r and Crebh in this process. We found that alcohol exposure or Cb1r-agonist 2-AG treatment increases hepatic bile acid synthesis and serum ALT, AST levels in vivo alongwith significant increase in Crebh gene expression and activation. Alcohol exposure activated Cb1r, Crebh, and perturbed bile acid homeostasis. Overexpression of Crebh increased the expression of key bile acid synthesis enzyme genes via direct binding of Crebh to their promoters, whereas Cb1r knockout and Crebh-knockdown mice were protected against alcohol-induced perturbation of bile acid homeostasis. Interestingly, insulin treatment protected against Cb1r-mediated Crebh-induced disruption of bile acid homeostasis. Furthermore, Crebh expression and activation was found to be markedly increased in insulin resistance conditions and Crebh knockdown in diabetic mice model (db/db) significantly reversed alcohol-induced disruption of bile acid homeostasis. Overall, our study demonstrates a novel regulatory mechanism of hepatic bile acid metabolism by alcohol via Cb1r-mediated activation of Crebh, and suggests that targeting Crebh can be of therapeutic potential in ameliorating alcohol-induced perturbation of bile acid homeostasis.
Chanda D; Kim Y H; Li T; Misra J; Kim D K; Kim J R; Kwon J; Jeong W I; Ahn S H; Park T S; Koo S H; Chiang J Y L; Lee C H; Choi H S
PLOS ONE
2013
2013-07
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1371/journal.pone.0068845" target="_blank" rel="noreferrer noopener">10.1371/journal.pone.0068845</a>
Fenofibrate Differentially Regulates Plasminogen Activator Inhibitor-1 Gene Expression via Adenosine Monophosphate-Activated Protein Kinase-Dependent Induction of Orphan Nuclear Receptor Small Heterodimer Partner
cells; binding; complex; fibrosis; Gastroenterology & Hepatology; promoter; beta; mechanisms; pai-1; shp; smad3
Plasminogen activator inhibitor type I (PAI-1) is a marker of the fibrinolytic system and serves as a possible predictor for hepatic metabolic syndromes. Fenofibrate, a peroxisome proliferator-activated receptor alpha (PPAR alpha) agonist, is a drug used for treatment of hyperlipidemia. Orphan nuclear receptor small heterodimer partner (SHP) plays a key role in transcriptional repression of crucial genes involved in various metabolic pathways. In this Study, we show that fenofibrate increased SHP gene expression in cultured liver cells and in the normal and diabetic mouse liver by activating the adenosine monophosphate-activated protein kinase (AMPK signaling pathway in a PPAR alpha-independent manner. Administration of transforming growth factor beta (TGF-beta) or a methionine-deficient and choline-deficient (MCD) diet to induce the progressive fibrosing steatohepatitis model in C57BL/6 mice was significantly reversed by fenofibrate via AMPK-mediated induction of SHP gene expression with a dramatic decrease in PAI-1 messenger RNA (mRNA) and protein expression along with other fibrotic marker genes. No reversal was observed in SHP null mice treated with fenofibrate. Treatment with another PPAR alpha agonist, WY14643, showed contrasting effects on these marker gene expressions in wild-type and SHP null mice, demonstrating the specificity of fenofibrate in activating AMPK signaling. Fenofibrate exhibited a differential inhibitory pattern on PAI-1 gene expression depending on the transcription factors inhibited by SHP. Conclusion: By demonstrating that a PPAR alpha-independent fenofibrate-AMPK-SHP regulatory cascade can play a key role in PAI-1 gene down-regulation and reversal of fibrosis, our study suggests that various AMPK activators regulating SHP might provide a novel pharmacologic option in ameliorating hepatic metabolic syndromes. (HEPATOLOGY 2009;50:880-892.)
Chanda D; Lee C H; Kim Y H; Noh J R; Kim D K; Park J H; Hwang J H; Lee M R; Jeong K H; Lee I K; Kweon G R; Shong M; Oh G T; Chiang J Y L; Choi H S
Hepatology
2009
2009-09
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1002/hep.23049" target="_blank" rel="noreferrer noopener">10.1002/hep.23049</a>
Hepatocyte Growth Factor Family Negatively Regulates Hepatic Gluconeogenesis via Induction of Orphan Nuclear Receptor Small Heterodimer Partner in Primary Hepatocytes
signaling pathway; mice; hyperglycemia; Biochemistry & Molecular Biology; gene-expression; promoter; activated protein-kinase; insulin; diabetic-nephropathy; hepg2 liver-cells; upstream
Hepatic gluconeogenesis is tightly balanced by opposing stimulatory (glucagon) and inhibitory (insulin) signaling pathways. Hepatocyte growth factor (HGF) is a pleiotropic growth factor that mediates diverse biological processes. In this study, we investigated the effect of HGF and its family member, macrophage-stimulating factor (MSP), on hepatic gluconeogenesis in primary hepatocytes. HGF and MSP significantly repressed expression of the key hepatic gluconeogenic enzyme genes, phosphoenolpyruvate carboxykinase (PEPCK), and glucose-6-phosphatase (Glc-6-Pase) and reduced glucose production. HGF and MSP activated small heterodimer partner (SHP) gene promoter and induced SHP mRNA and protein levels, and the effect of HGF and MSP on SHP gene expression was demonstrated to be mediated via activation of the AMP-activated protein kinase (AMPK) signaling pathway. We demonstrated that upstream stimulatory factor-1 (USF-1) specifically mediated HGF effect on SHP gene expression, and inhibition of USF-1 by dominant negative USF-1 significantly abrogated HGF-mediated activation of the SHP promoter. Elucidation of the mechanism showed that USF-1 bound to E-box-1 in the SHP promoter, and HGF increased USF-1 DNA binding on the SHP promoter via AMPK and DNA-dependent protein kinase-mediated pathways. Adenoviral overexpression of USF-1 significantly repressed PEPCK and Glc-6-Pase gene expression and reduced glucose production. Knockdown of endogenous SHP expression significantly reversed this effect. Finally, knockdown of SHP or inhibition of AMPK signaling reversed the ability of HGF to suppress hepatocyte nuclear factor 4 alpha-mediated up-regulation of PEPCK and Glc-6-Pase gene expression along with the HGF- and MSP-mediated suppression of gluconeogenesis. Overall, our results suggest a novel signaling pathway through HGF/AMPK/USF-1/SHP to inhibit hepatic gluconeogenesis.
Chanda D; Li T G; Song K H; Kim Y H; Sim J G; Lee C H; Chiang J Y L; Choi H S
Journal of Biological Chemistry
2009
2009-10
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1074/jbc.M109.022244" target="_blank" rel="noreferrer noopener">10.1074/jbc.M109.022244</a>
Orphan Nuclear Receptor Small Heterodimer Partner Negatively Regulates Growth Hormone-mediated Induction Of Hepatic Gluconeogenesis Through Inhibition Of Signal Transducer And Activator Of Transcription 5 (stat5) Transactivation
ampk; ataxia-telangiectasia; atm; Biochemistry & Molecular Biology; expression; Glucose; glucose-6-phosphatase gene; involvement; metformin; protein kinase; shp
Growth hormone (GH) is a key metabolic regulator mediating glucose and lipid metabolism. Ataxia telangiectasia mutated (ATM) is a member of the phosphatidylinositol 3-kinase superfamily and regulates cell cycle progression. The orphan nuclear receptor small heterodimer partner (SHP: NR0B2) plays a pivotal role in regulating metabolic processes. Here, we studied the role of ATM on GH-dependent regulation of hepatic gluconeogenesis in the liver. GH induced phosphoenolpyruvate carboxykinase (PEPCK) and glucose 6-phosphatase gene expression in primary hepatocytes. GH treatment and adenovirus-mediated STAT5 overexpression in hepatocytes increased glucose production, which was blocked by a JAK2 inhibitor, AG490, dominant negative STAT5, and STAT5 knockdown. We identified a STAT5 binding site on the PEPCK gene promoter using reporter assays and point mutation analysis. Up-regulation of SHP by metformin-mediated activation of the ATM-AMP-activated protein kinase pathway led to inhibition of GH-mediated induction of hepatic gluconeogenesis, which was abolished by an ATM inhibitor, KU-55933. Immunoprecipitation studies showed that SHP physically interacted with STAT5 and inhibited STAT5 recruitment on the PEPCK gene promoter. GH-induced hepatic gluconeogenesis was decreased by either metformin or Ad-SHP, whereas the inhibition by metformin was abolished by SHP knockdown. Finally, the increase of hepatic gluconeogenesis following GH treatment was significantly higher in the liver of SHP null mice compared with that of wildtype mice. Overall, our results suggest that the ATM-AMP-activated protein kinase-SHP network, as a novel mechanism for regulating hepatic glucose homeostasis via a GH-dependent pathway, may be a potential therapeutic target for insulin resistance.
Kim Y D; Li T G; Ahn S W; Kim D K; Lee J M; Hwang S L; Kim Y H; Lee C H; Lee I K; Chiang J Y L; Choi H S
Journal of Biological Chemistry
2012
2012-10
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1074/jbc.M112.339887" target="_blank" rel="noreferrer noopener">10.1074/jbc.M112.339887</a>
Ampk-dependent Repression Of Hepatic Gluconeogenesis Via Disruption Of Creb Center Dot Crtc2 Complex By Orphan Nuclear Receptor Small Heterodimer Partner
activated protein-kinase; binding-protein; Biochemistry & Molecular Biology; creb coactivator crtc2; gene-expression; insulin; metformin; phosphorylation; shp; torc2; transcriptional activity
Orphan nuclear receptor small heterodimer partner (SHP) plays a key role in transcriptional repression of gluconeogenic enzyme gene expression. Here, we show that SHP inhibited protein kinase A-mediated transcriptional activity of cAMP-response element-binding protein (CREB), a major regulator of glucose metabolism, to modulate hepatic gluconeogenic gene expression. Deletion analysis of phosphoenolpyruvate carboxykinase (PEPCK) promoter demonstrated that SHP inhibited forskolin-mediated induction of PEPCK gene transcription via inhibition of CREB transcriptional activity. In vivo imaging demonstrated that SHP inhibited CREB-regulated transcription coactivator 2 (CRTC2)-mediated cAMP-response element-driven promoter activity. Furthermore, overexpression of SHP using adenovirus SHP decreased CRTC2-dependent elevations in blood glucose levels and PEPCK or glucose-6-phosphatase (G6Pase) expression in mice. SHP and CREB physically interacted and were co-localized in vivo. Importantly, SHP inhibited both wild type CRTC2 and S171A (constitutively active form of CRTC2) coactivator activity and disrupted CRTC2 recruitment on the PEPCK gene promoter. In addition, metformin or overexpression of a constitutively active form of AMPK (Ad-CA-AMPK) inhibited S171A-mediated PEPCK and G6Pase gene expression, and hepatic glucose production and knockdown of SHP partially relieved the metformin- and Ad-CA-AMPK-mediated repression of hepatic gluconeogenic enzyme gene expression in primary rat hepatocytes. In conclusion, our results suggest that a delayed effect of metformin-mediated induction of SHP gene expression inhibits CREB-dependent hepatic gluconeogenesis.
Lee J M; Seo W Y; Song K H; Chanda D; Kim Y D; Kim D K; Lee M W; Ryu D; Kim Y H; Noh J R; Lee C H; Chiang J Y L; Koo S H; Choi H S
Journal of Biological Chemistry
2010
2010-10
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1074/jbc.M110.134890" target="_blank" rel="noreferrer noopener">10.1074/jbc.M110.134890</a>