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Hepcidin (HAMP) is synthesized in the liver. It is a key ironregulatory hormone that controls systemic iron homeostasis. Cereblon (CRBN) and Kruppel-like factor 15 (KLF15) are known to regulate diverse physiological functions. In this study, we investigated the role of CRBN on hepatic hepcidin gene expression and production under gluconeogenic stimuli. Fasted mice as well as forskolin (FSK)- and glucagon (GLU)-treated mice had reduced serum iron levels but increased expression levels of hepatic Crbn and Klf15 and hepcidin secretion. MicroRNA (miRNA) expression analysis of fasted and Ad-Crbninfected mice revealed significant reduction of microRNA-639 (miR-639). Hepatic overexpression of Crbn elevated hepcidin expression and production along with Klf15 gene expression, whereas knockdown of Crbn and Klf15 markedly decreased FSK- and fasting-mediated induction of hepcidin gene expression and its biosynthesis in mouse livers and primary hepatocytes. Moreover, expression of KLF15 significantly increased the activity of hepcidin reporter gene. It was exclusively dependent on the KLF15-binding site identified within the hepcidin gene promoter. Overall, this study demonstrates that CRBN and KLF15 are novel mediators of gluconeogenic signal-induced hepcidin gene expression and production. Thus, CRBN and KLF15 might be novel potential therapeutic targets to intervene metabolic dysfunction. [BMB Reports 2021; 54(4): 221-226].

Growth hormone (GH) is one of the critical factors in maintaining glucose metabolism. B-cell translocation gene 2 (BTG2) and yin yang 1 (YY1) are key regulators of diverse metabolic processes. In this study, we investigated the link between GH and BTG2–YY1 signaling pathway in glucose metabolism. GH treatment elevated the expression of hepatic Btg2 and Yy1 in primary mouse hepatocytes and mouse livers. Glucose production in primary mouse hepatocytes and serum blood glucose levels were increased during GH exposure. Overexpression of hepatic Btg2 and Yy1 induced key gluconeogenic enzymes phosphoenolpyruvate carboxykinase 1 (PCK1) and glucose-6 phosphatase (G6PC) as well as glucose production in primary mouse hepatocytes, whereas this phenomenon was markedly diminished by knockdown of Btg2 and Yy1. Here, we identified the YY1-binding site on the Pck1 and G6pc gene promoters using reporter assays and point mutation analysis. The regulation of hepatic gluconeogenic genes induced by GH treatment was clearly linked with YY1 recruitment on gluconeogenic gene promoters. Overall, this study demonstrates that BTG2 and YY1 are novel regulators of GH-dependent regulation of hepatic gluconeogenic genes and glucose production. BTG2 and YY1 may be crucial therapeutic targets to intervene in metabolic dysfunction in response to the GH-dependent signaling pathway.

Background: Nogo-A (Rtn 4A), a member of the reticulon 4 (Rtn4) protein family, is a neurite outgrowth inhibitor protein that is primarily expressed in the central nervous system (CNS). However, the role of Nogo-A in inflammatory mechanisms remains unclear. Therefore, in this study, we used Nogo-knockout (KO) mice to explore its potential role in the inflammatory process. Here, we investigated whether Nogo-A affects the inflammatory process through transcription factor C/EBP homologous protein (CHOP). Results: Our results demonstrated that Nogo-A, CHOP, and pro-inflammatory factors were activated in the following: notexin-induced muscle injury, in human Duchenne muscular dystrophy (DMD) patients, in dystrophin-deficient (mdx) mice, in differentiated C2C12 myoblast cells, and in lipopolysaccharide (LPS)-stimulated bone marrow-derived macrophages (BMDM). Moreover, we found that Nogo-KO BMDM exhibited lower migratory ability compared with wild type (WT) BMDM after LPS treatment. Conclusion: Our data demonstrated that the Nogo-A-CHOP signaling pathway regulated the inflammatory process in notexin-induced injured muscle, in mdx mice, in DMD patients, in differentiated C2C12 cells, and in LPS-stimulated BMDM. Taken together, these results suggest that Nogo-A plays a vital role in inflammatory processes, which resembles the pathological mechanisms observed in the CNS.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A 5 yr old, 184 kg, and 262 cm total length female bottlenose dolphin Tursiops truncatus was found dead in a display after bloody discharge from the blowhole was observed 3 h prior to death. Pathological examination revealed fibrinous bronchopneumonia with prominent areas of necrosis (sequestra) and numerous Gram-negative bacilli within alveoli and in blood vessels of the lungs and liver and between muscle fibers. The cause of death was attributed to septicemia. Often, cases of fibrinous bronchopneumonia are characterized by bacteremia in the latter stages of infection, resulting in the death of the animal. Septicemia likely accounts for the ecchymoses and petechiae noted on the spleen, pancreas, forestomach, lungs, visceral peritoneum, and small intestine. Additional lesions included hemothorax, stable red frothy fluid in the trachea, and lymphoid depletion in the spleen and lymph nodes. Pure growth of Morganella morganii was isolated from the lungs, blood, liver, and blowhole mucosa. Sequencing of 16s rRNA of the isolated bacteria showed more than 99.6% identity with M. morganii strain FDAARGOS_172. To our knowledge, this is the first report of fatal fibrinonecrotizing bronchopneumonia associated with M. morganii infection in a cetacean.

Here we describe the histological lesion of a viral fibro-papilloma in a hedgehog. After surgical removal from maxilla, the solitary swollen mass was round to oval, yellowish with rough surface and measuring 6×3×2mm approximately. The tumor mass was submitted to the laboratory of pathology, college of veterinary medicine, Kyungpook National University for pathological diagnosis. Pathological examination of the tumor was established, the tumor was described grossly and sample was trimmed, sectioned and routinely prepared for histopathological evaluation. The tumor mass was diagnosed as viral fibro-papilloma, as the histological picture showed characteristic features of warts caused by papillomaviruses. The tumor characterized by thickening of the stratum spinosum (acanthosis) and basale, koilocytosis, intra-nuclear inclusion bodies in keratinocytes and fibrosis of submucosa. Further, viral inclusion bodies were demonstrated by Machiavello stain giving red color to the nuclei. No lymphocytes that responsible for regression of the wart could be detected, suggesting the poor possibility of spontaneous regression of the tumor. Papillomatosis is a disease of young animals, but in our case the infected Hedgehog was 5 years old, that maybe due to an impaired immune system, which is also shown by absence of lymphocytes. To the best knowledge of the author, this case presents the first report of viral fibropapillomatosis in Hedgehog.

Ascorbic acid (AA) is recognized as a free radical scavenger that protects cells from oxidative stress-induced damage. However, no studies have investigated the role of AA in acute alcoholic liver disease using senescence marker protein-30 (SMP30) knockout (KO) mice. SMP30 is a novel 34-kDa protein involved in AA biosynthesis. The present study aimed to elucidate the physiological functions of AA in acute ethanol-induced liver injury using SMP30 KO mice, which cannot synthesize AA in vivo. After a 4-week experimental period, mice were divided into six groups. The following three groups comprised the ethanol treatment groups: WT-E group (wild-type), KV-E group (AA-supplemented), and KT-E group (AA-deficient). Mice were exposed to an acute dose of ethanol (6 g ethanol/kg) administered by gavage once a day for three days. The other three control groups, namely, WT-C, KV-C, and KT-C control groups, received an equal volume of water via oral administration. Analysis of changes in body weight showed that mice in the KT-E group had significant loss of body weight compared to the control, KV-E, and WT-E groups. Behavioral analysis revealed that alcohol exposure significantly increased alcohol sensitivity in the KT-E group, whereas the WT-E, KV-E, and control groups developed ethanol tolerance. Aspartate transaminase (AST) levels in the KT-E group were significantly higher than those in the control, KV-E, and WT-E groups. The number of large and binucleated hepatocytes was significantly higher in the KT-E group than in the KV-E and WT-E groups. In addition, cytochrome P450 2E1 (CYP2E1) was over expressed in the central vein in the KT-E group when compared to the KV-E and WT-E groups. Our current findings indicate that AA supplementation in SMP30 KO mice can alleviate alcohol-induced liver damage by down regulating CYP2E1 expression. These results suggest that reduced CYP2E1 expression is a novel mechanism responsible for AA-induced reduction of ethanol-mediated oxidative stress.

Piperaceae plants consist of about 3600 species, of which about 2000 are Piper plants. Their habitat is distributed across pantropical regions. The representative plant is Piper nigrum, known as black pepper. These plants have been widely used in folk medicine in Korean traditional medicine. This review collected papers identifying and separating the amides obtained from these Piper plants, with a focus on Piper amides potential to control the production and growth of fungal strains that cause plant disease and their insecticidal properties against agricultural pests. Piper amide benefits include antiaflatoxigenic activities, antiparasitic activities, anticancer properties, antiplatelet activities, and anti-inflammatory activities, among other therapeutic properties for the treatment of human diseases. In addition, this review paper provides a total synthesis study on the mass production of Piper amides and their derivatives, with a formulation study for industrial use. This review paper is designed to help inform future studies on Piper amide applications.

In this study, the antimelanogenic activity of piperlongumine in murine B16F10 melanoma cells and zebrafish was investigated, and its mode of antimelanogenic action was elucidated using quantitative reverse transcription-polymerase chain reaction. A melanocyte-stimulating hormone (α-MSH, 200 nM) was used to induce melanin production in B16F10 melanoma cells, and kojic acid (200 μM) was used as a positive control. Piperlongumine had no inhibitory effects on cell growth at the treated concentrations (3 and 6 μM), and it significantly reduced total melanin production. Piperlongumine decreased the expression of Mitf, Tyr, Trp-1, and Trp-2 and tyrosinase activity was also dramatically reduced by the piper amide addition under α-MSH treatment. With these findings, zebrafish embryos were used to confirm antimelanogenic activity of piperlongumine, and it showed the potent antimelanogenic activity at the concentration of 1 μM. Altogether, piperlongumine has potent antimelanogenic activity, and these results support it as a candidate for natural depigmentation agent in a cosmetic and pharmaceutical industries.

Alcoholic liver disease is the most prevalent chronic liver disease. Melatonin is known to control many vital processes. Here, we explored a novel molecular mechanism by which melatonin-induced SIRT1 signaling protects against alcohol-mediated oxidative stress and liver injury. Gene expression profiles and metabolic changes were measured in liver specimens of mice and human subjects. Expression levels of Cb1r, Crbn, Btg2, Yy1, pro-inflammatory cytokines, and Cyp2e1 were significantly enhanced in chronic alcohol-challenged mice and human subjects. Levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), hepatic CYP2E1 protein, and reactive oxygen species (ROS) were elevated in alcohol-fed WT mice but not in Cb1r antagonist-treated, Crbn null, or Yy1-silenced mice. Importantly, alcohol-induced Yy1 and Cyp2e1 expression, ROS amount, and liver injury were markedly diminished by melatonin treatment and the transduction of Sirt1 in mice, whereas this phenomenon was prominently ablated by silencing of Sirt1. Notably, SIRT1 physically interacted with YY1 and attenuated YY1 occupancy on the Cyp2e1 gene promoter. Melatonin-SIRT1 signaling ameliorates alcohol-induced oxidative liver injury by disrupting the CRBN-YY1-CYP2E1 signaling pathway. The manipulation of CRBN-YY1-CYP2E1 signaling network by the melatonin-SIRT1 pathway highlights a novel entry point for treating alcoholic liver disease.

Alcohol consumption exacerbates alcoholic liver disease by attenuating the activity of AMP-activated protein kinase (AMPK). AMPK is activated by fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) agonist, and inhibited by direct interaction with cereblon (CRBN), a component of an E3 ubiquitin ligase complex. Based on these preliminary findings, we investigated that CRBN would be up-regulated in the liver by alcohol consumption and that CRBN deficiency would ameliorate hepatic steatosis and pro-inflammatory responses in alcohol-fed mice by increasing AMPK activity. Wild-type, CRBN and PPARα null mice were fed an alcohol-containing liquid diet and administered with fenofibrate. Gene expression profiles and metabolic changes were measured in the liver and blood of these mice. Expression of CRBN, cytochrome P450 2E1 (CYP2E1), lipogenic genes, pro-inflammatory cytokines, serum alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were increased in the Lieber–DeCarli alcohol-challenged mice. Fenofibrate attenuated the induction of CRBN and reduced hepatic steatosis and pro-inflammatory markers in these mice. Ablation of the gene encoding CRBN produced the same effect as fenofibrate. The increase in CRBN gene expression by alcohol and the reduction of CRBN expression by fenofibrate were negated in PPARα null mice. Fenofibrate increased the recruitment of PPARα on CRBN gene promoter in WT mice but not in PPARα null mice. Silencing of AMPK prevented the beneficial effects of fenofibrate. These results demonstrate that activation of PPARα by fenofibrate alleviates alcohol-induced hepatic steatosis and inflammation by reducing the inhibition of AMPK by CRBN. CRBN is a potential therapeutic target for the alcoholic liver disease.

Life-long regeneration of healthy muscle by cell transplantation is an ideal therapy for patients with degenerative muscle diseases. Yet, obtaining muscle stem cells from patients is very limited due to their exhaustion in disease condition. Thus, development of a method to obtain healthy myogenic stem cells is required. Here, we showed that the four transcription factors, Six1, Eya1, Esrrb, and Pax3, converts fibroblasts into induced myogenic stem cells (iMSCs). The iMSCs showed effective differentiation into multinucleated myotubes and also higher proliferation capacity than muscle derived stem cells both in vitro and in vivo. The iMSCs do not lose their proliferation capacity though the passaging number is increased. We further isolated CD106-negative and α7-integrin-positive iMSCs (sort-iMSCs) showing higher myogenic differentiation capacity than iMSCs. Moreover, genome-wide transcriptomic analysis of iMSCs and sort-iMSCs, followed by network analysis, revealed the genes and signaling pathways associated with enhanced proliferation and differentiation capacity of iMSCs and sort-iMSCs, respectively. The stably expandable iMSCs provide a new source for drug screening and muscle regenerative therapy for muscle wasting disease.

Fibroblast growth factor 21 (FGF21) is a hormone that is vital for the regulation of metabolic homeostasis. In the present study, we report that Kruppel-like factor 15 (KLF15) is a novel mediator of b-cell translocation gene 2 (BTG2)-induced FGF21 biosynthesis. The expression levels of hepatic Fgf21, Btg2, and Klf15, and the production of serum FGF21 increased significantly in fasted and forskolin (FSK)-treated mice. The overexpression of Btg2 using an adenoviral delivery system elevated FGF21 production by upregulating Klf15 transcription. Interaction studies indicated that BTG2 was co-immunoprecipitated with KLF15 and recruited by the Fgf21 promoter. The disruption of hepatic Btg2 and Klf15 genes markedly attenuated the induction of Fgf21 expression and FGF21 biosynthesis in fasted mice. Similarly, the FSK-mediated induction of Fgf21 promoter activity was strikingly ablated by silencing of Btg2 and Klf15. Taken together, these findings suggest that KLF15 and BTG2 are mediators of fasting-induced hepatic FGF21 expression. Therefore, targeting BTG2 and KLF15 might be a therapeutically important strategy for combat metabolic dysfunction.

Vitamin C (L-ascorbic acid) is well known as a free radical scavenger that protects cells against damage from oxidative stress. Herein, we investigated the effects of vitamin C against diethylnitrosamine (DEN)-induced hepatotoxicity. Male wild-type (C57BL/6) and senescence marker protein-30 (Smp30) knockout (KO) mice were used and divided in the following four groups: WT group (n=15): Wild-type (WT) mice fed vitamin C-free diet with tap water; WV group (n=14): WT mice fed vitamin C-free diet with water supplemented with 1.5 g/kg vitamin C; KT group (n=12): Smp30 KO mice fed vitamin C-free diet with tap water; and KV group (n=13): Smp30 KO mice fed vitamin C-free diet with water supplemented with 1.5 g/kg vitamin C. A single intraperitoneal injection of DEN (5 mg/kg body weight) was injected in the second week during the experimental period. Mice were sacrificed after 17 weeks of treatment to investigate the effect of dietary vitamin C on DEN-induced hepatotoxicity. The results showed that vitamin C significantly increased the mean lifespan (p

Capsosiphon fulvescens (green seaweed) and Hizikia fusiforme (brown seaweed) are marine algae consumed as food supplements, especially in Japan, China and Korea, and are considered traditional medicinal tonics for certain ailments. The aim of this study was to investigate the possible inhibitory effects of dietary C. fulvescens and H. fusiforme on azoxymethane (AOM)-induced colorectal cancer (CRC) in rats. F344 male rats (5 weeks, 150 g) were divided into six groups as follows. Group 1: Injected with normal saline solution and fed control diet (untreated control). Group 2: Injected with AOM and fed control diet (treated control). Group 3: Injected with AOM and fed 1% C. fulvescens diet. Group 4: Injected with AOM and fed 2% C. fulvescens diet. Group 5: Injected with AOM and fed 2% H. fusiforme diet. Group 6: Injected with AOM and fed 6% H. fusiforme diet. Test animals received subcutaneous injections of AOM (15 mg/1 ml/kg body weight) once a week for 2 weeks to induce aberrant crypt foci (ACF) in treated control and experimental groups. We evaluated the effects of dietary C. fulvescens and H. fusiforme at two different dose levels: 1 and 2% C. fulvescens, and 2 and 6% H. fusiforme, on colonic carcinogenesis by AOM in rats. Our results suggest that body weights were not significantly different amongst groups. We found that feeding C. fulvescens and H. fusiforme with a control diet significantly (p

The authors wish to thank National Research Foundation (NRF) Singapore (grant WBS nos. R-265-000-399-281 and R-265-000-466-281) and King Abdullah University of Science & Technology (KAUST) (Project no. 7000000411) for financial support for MED plant.

Insulin-like growth factor (IGF)-binding protein-2 (IGFBP-2), one of the most abundant circulating IGFBPs, is known to attenuate the biological action of IGF-1. Although the effect of IGFBP-2 in preventing metabolic disorders is well known, its regulatory mechanism remains unclear. In the present study, we demonstrated the transcriptional regulation of the Igfbp-2 gene by peroxisome-proliferator-activated receptor (PPAR) α in the liver. During fasting, both Igfbp-2 and PPARα expression levels were increased. Wy14643, a selective PPARα agonist, significantly induced Igfbp-2 gene expression in primary cultured hepatocytes. However, Igfbp-2 gene expression in Pparα null mice was not affected by fasting or Wy14643. In addition, through transient transfection and chromatin immunoprecipitation assay in fasted livers, we determined that PPARα bound to the putative PPAR-responsive element between −511 bp and −499 bp on the Igfbp-2 gene promoter, indicating that the Igfbp-2 gene transcription is activated directly by PPARα. To explore the role of PPARα in IGF-1 signalling, we treated primary cultured hepatocytes with Wy14643 and observed a decrease in the number of IGF-1 receptors (IGF-1Rs) and in Akt phosphorylation. No inhibition was observed in the hepatocytes isolated from Pparα null mice. These results suggest that PPARα controls IGF-1 signalling through the up-regulation of hepatic Igfbp-2 transcription during fasting and Wy14643 treatment., Insulin-like growth factor (IGF)-binding protein-2 (IGFBP-2) is known to attenuate the biological action of IGF-1, but its regulatory mechanism remains unclear. We demonstrate the transcriptional regulation of the hepatic Igfbp-2 gene by peroxisome-proliferator-activated receptor (PPAR) α during fasting. We also show how PPARα controls IGF-1 signalling through IGFBP-2.

Capsosiphon fulvescens (green seaweed) and Hizikia fusiforme (brown seaweed) are marine algae consumed as food supplements, especially in Japan, China and Korea, and are considered traditional medicinal tonics for certain ailments. The aim of this study was to investigate the possible inhibitory effects of dietary C. fulvescens and H. fusiforme on azoxymethane (AOM)-induced colorectal cancer (CRC) in rats. F344 male rats (5 weeks, 150 g) were divided into six groups as follows. Group 1: Injected with normal saline solution and fed control diet (untreated control). Group 2: Injected with AOM and fed control diet (treated control). Group 3: Injected with AOM and fed 1% C. fulvescens diet. Group 4: Injected with AOM and fed 2% C. fulvescens diet. Group 5: Injected with AOM and fed 2% H. fusiforme diet. Group 6: Injected with AOM and fed 6% H. fusiforme diet. Test animals received subcutaneous injections of AOM (15 mg/1 ml/kg body weight) once a week for 2 weeks to induce aberrant crypt foci (ACF) in treated control and experimental groups. We evaluated the effects of dietary C. fulvescens and H. fusiforme at two different dose levels: 1 and 2% C. fulvescens, and 2 and 6% H. fusiforme, on colonic carcinogenesis by AOM in rats. Our results suggest that body weights were not significantly different amongst groups. We found that feeding C. fulvescens and H. fusiforme with a control diet significantly (p

Helicobacter pylori, a gram-negative bacterium, is the causative agent of gastric disorders and gastric cancer in the human stomach. Vacuolating cytotoxin A (VacA) is among the multi-effect protein toxins released by H. pylori that enables its persistence in the human stomach.To evaluate the effect of anti-VacA egg yolk immunoglobulin (anti-VacA IgY) on H. pylori infection, a highly specific anti-VacA IgY was produced from egg yolks of hens immunized with a mixture of two purified recombinant VacAs. Female C57BL/6 mice were supplemented anti-VacA IgY daily with drinking water for 2 weeks before and 4 weeks after H. pylori ATCC 43504 inoculation. Anti-VacA IgY recognized both native and denatured structures of VacA by enzyme-linked immunosorbent assay and immunoblotting analyses, respectively.Oral administration of anti-VacA IgYs significantly (p .05) reduced the serum levels of anti-H. pylori antibodies compared to those in the H. pylori-infected, untreated group. The reduction in the immune response was accompanied by a significant (p .05) decrease in eosinophilic infiltration of the stomach in anti-VacA IgY treated group compared to other groups. Concomitantly, H. pylori-induced histological changes and H. pylori antigen-positivity in gastric tissues were decreased significantly (p .05) in anti-VacA IgY treated group similar to the control group.Oral administration of anti-VacA IgY is correlated with a protective effect against H. pylori colonization and induced histological changes in gastric tissues. Our experimental study has proved that it is expected to be a new drug candidate of Hp infection by further study.

B-cell translocation gene 2 (BTG2) is a member of an emerging gene family that is involved in cellular functions. In this study, we demonstrate that BTG2 regulates glucose homeostasis via upregulation of Nur77 in diabetic mice. Hepatic BTG2 gene expression was elevated by fasting and forskolin. Overexpression of Btg2 increased the expression of hepatic gluconeogenic genes and blood glucose output and subsequently impaired glucose and insulin tolerance. Upregulation of the transcriptional activity of Nur77, gluconeogenic genes, and glucose production by forskolin was observed by Btg2 transduction, but not in Btg2 knockdown. BTG2-stimulated glucose production and glucose-6-phosphatase promoter activity were attenuated by dominant-negative Nur77. Coimmunoprecipitation and chromatin immunoprecipitation assays showed that BTG2 induced Nur77 occupancy on the glucose-6-phosphatase promoter via a physical interaction. Btg2 gene expression was increased in streptozotocin-treated and db/db mice. Finally, impairment of glucose homeostasis, such as the increase of blood glucose, glucose intolerance, and insulin intolerance, was elevated in diabetic mice, whereas this phenomenon was abolished in knockdown of Btg2. Together, these data suggest that BTG2 participates in the regulation of hepatic glucose homeostasis, which means that BTG2 might serve as a potential therapeutic target for combating metabolic dysfunction.

In response to microbial infection, expression of the defensin-like peptide hepcidin (encoded by Hamp) is induced in hepatocytes to decrease iron release from macrophages. To elucidate the mechanism by which Salmonella enterica var. Typhimurium (S. typhimurium), an intramacrophage bacterium, alters host iron metabolism for its own survival, we examined the role of nuclear receptor family members belonging to the NR3B subfamily in mouse hepatocytes. Here, we report that estrogen-related receptor γ (ERRγ, encoded by Esrrg) modulates the intramacrophage proliferation of S. typhimurium by altering host iron homeostasis, and we demonstrate an antimicrobial effect of an ERRγ inverse agonist. Hepatic ERRγ expression was induced by S. typhimurium-stimulated interleukin-6 signaling, resulting in an induction of hepcidin and eventual hypoferremia in mice. Conversely, ablation of ERRγ mRNA expression in liver attenuated the S. typhimurium-mediated induction of hepcidin and normalized the hypoferremia caused by S. typhimurium infection. An inverse agonist of ERRγ ameliorated S. typhimurium-mediated hypoferremia through reduction of ERRγ-mediated hepcidin mRNA expression and exerted a potent antimicrobial effect on the S. typhimurium infection, thereby improving host survival. Taken together, these findings suggest an alternative approach to control multidrug-resistant intracellular bacteria by modulating host iron homeostasis.

Small heterodimer partner interacting leucine zipper protein (SMILE) has been identified as a nuclear corepressor of the nuclear receptor (NRs) family. Here, we examined the role of SMILE in the regulation of nuclear receptor liver X receptor (LXRα)-mediated sterol regulatory element binding protein-1c (SREBP-1c) gene expression. We found that SMILE inhibited T0901317 (T7)-induced transcriptional activity of LXRα, which functions as a major regulator of lipid metabolism by inducing SREBP-1c, fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC) gene expression. Moreover, we demonstrated that SMILE physically interacts with LXRα and represses T7-induced LXRα transcriptional activity by competing with coactivator SRC-1. Adenoviral overexpression of SMILE (Ad-SMILE) attenuated fat accumulation and lipogenic gene induction in the liver of T7 administered or of high fat diet (HFD)-fed mice. Furthermore, we investigated the mechanism by which ursodeoxycholic acid (UDCA) inhibits LXRα-induced lipogenic gene expression. Interestingly, UDCA treatment significantly increased SMILE promoter activity and gene expression in an adenosine monophosphate-activated kinase-dependent manner. Furthermore, UDCA treatment repressed T7-induced SREBP-1c, FAS, and ACC protein levels, whereas knockdown of endogenous SMILE gene expression by adenovirus SMILE shRNA (Ad-shSMILE) significantly reversed UDCA-mediated repression of SREBP-1c, FAS, and ACC protein levels. Collectively, these results demonstrate that UDCA activates SMILE gene expression through adenosine monophosphate-activated kinase phosphorylation, which leads to repression of LXRα-mediated hepatic lipogenic enzyme gene expression.

Glyceollin has been shown to have antidiabetic properties, although its molecular mechanism is not known. Here, we have investigated the metabolic effects of glyceollin in animal models of insulin resistance and in endoplasmic reticulum (ER) stress-responsive muscle cells. db/db mice were treated with glyceollin for 4weeks and triglycerides, total cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) levels were measured. Glyceollin reduced serum insulin and triglycerides and increased HDL levels in db/db mice. Furthermore, glyceollin caused a significant improvement in glucose homeostasis without altering body weight and food intake in db/db mice. In muscle cells, glyceollin increased the activity of AMP-activated protein kinase (AMPK) as well as cellular glucose uptake. Fatty acid oxidation was also increased. In parallel, phosphorylation of acetyl-CoA carboxylase (ACC) at Ser-79 was increased, consistent with decreased ACC activity. An insulin-resistant state was induced by exposing cells to 5μg/ml of tunicamycin as indicated by decreased insulin-mediated tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and glucose uptake. Inhibition of insulin-mediated tyrosine phosphorylation of IRS-1 and glucose uptake under ER stress was prevented by glyceollin. Strikingly, glyceollin reduced ER stress-induced, c-Jun NH2-terminal kinase activation and subsequently increased insulin signaling via stimulation of AMPK activity in L6 myotubes. Pharmacologic inhibition or knockdown of Ca(2+)/calmodulin-dependent protein kinase kinase blocked glyceollin-increased AMPK phosphorylation and insulin sensitivity under ER stress conditions. Taken together, these results indicate that glyceollin-mediated enhancement of insulin sensitivity under ER stress conditions is predominantly accomplished by activating AMPK, thereby having beneficial effects on hyperglycemia and insulin resistance.

A nonsense mutation in cereblon (CRBN) causes a mild type of mental retardation in humans. An earlier study showed that CRBN negatively regulates the functional activity of AMP-activated protein kinase (AMPK) in vitro by binding directly to the α1-subunit of the AMPK complex. However, the in vivo role of CRBN was not studied. For elucidation of the physiological functions of Crbn, a mouse strain was generated in which the Crbn gene was deleted throughout the whole body. In Crbn-deficient mice fed a normal diet, AMPK in the liver showed hyperphosphorylation, which indicated the constitutive activation of AMPK. Since Crbn-deficient mice showed significantly less weight gain when fed a high-fat diet and their insulin sensitivity was considerably improved, the functions of Crbn in the liver were primarily investigated. These results provide the first in vivo evidence that Crbn is a negative modulator of AMPK, which suggests that Crbn may be a potential target for metabolic disorders of the liver.

Background and Purpose Endoplasmic reticulum (ER) stress has been implicated in the pathogeneses of insulin resistance and type 2 diabetes, and extracellular signal-regulated kinase (ERK) antagonist is an insulin sensitizer that can restore muscle insulin responsiveness in both tunicamycin-treated muscle cells and type 2 diabetic mice. The present study was undertaken to determine whether the chemical or genetic inhibition ER stress pathway targeting by ERK results in metabolic benefits in muscle cells.

Alcoholic liver disease is a major cause of chronic liver disease worldwide, and cannabinoid receptor type 1 (CB1R) is involved in a diverse metabolic diseases. B-cell translocation gene 2 (BTG2) and yin yang 1 (YY1) are a potent regulator of biological conditions. Melatonin plays a crucial role in regulating diverse physiological functions and metabolic homeostasis. MicroRNAs are key regulators of various biological processes. Herein, we demonstrate that melatonin improves bile acid synthesis in the liver of alcohol-fed mice by controlling miR-497 expression. The level of bile acid and the expression of Cb1r, Btg2, Yy1, and bile acid synthetic enzymes were significantly elevated in the livers of Lieber-DeCarli alcohol-fed mice. The overexpression of Btg2 enhanced Yy1 gene expression and bile acid production, whereas disrupting the CB1R-BTG2-YY1 cascade protected against the bile acid synthesis caused by alcohol challenge. We identified an alcohol-mediated YY1 binding site on the cholesterol 7α-hydroxylase (Cyp7a1) gene promoter using promoter deletion analysis and chromatin immunoprecipitation assays. Notably, melatonin attenuated the alcohol-stimulated induction of Btg2, Yy1 mRNA levels and bile acid production by promoting miR-497. Overexpression of a miR-497 mimic dramatically diminished the increase of Btg2 and Yy1 gene expression as well as bile acid production by alcohol, whereas this phenomenon was reversed by miR-497 inhibitor. These results demonstrate that the upregulation of miR-497 by melatonin represses alcohol-induced bile acid synthesis by attenuating the BTG2-YY1 signaling pathway. The melatonin-miR497 signaling network may provide novel therapeutic targets for the treatment of hepatic metabolic dysfunction caused by the alcohol-dependent pathway.

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 wild-type 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.

Growth hormone (GH) is a counter-regulatory hormone that plays an important role in preventing hypoglycemia during fasting. Because inhibition of the pyruvate dehydrogenase complex (PDC) by pyruvate dehydrogenase kinase 4 (PDK4) conserves substrates for gluconeogenesis, we tested whether GH increases PDK4 expression in liver by a signaling pathway sensitive to inhibition by metformin. The effects of GH and metformin were determined in the liver of wild-type, small heterodimer partner (SHP)-, PDK4-, and signal transducer and activator of transcription 5 (STAT5)-null mice. Administration of GH in vivo increased PDK4 expression via a pathway dependent on STAT5 phosphorylation. Metformin inhibited the induction of PDK4 expression by GH via a pathway dependent on AMP-activated protein kinase (AMPK) and SHP induction. The increase in PDK4 expression and PDC phosphorylation by GH was reduced in STAT5-null mice. Metformin decreased GH-mediated induction of PDK4 expression and metabolites in wild-type but not in SHP-null mice. In primary hepatocytes, dominant-negative mutant-AMPK and SHP knockdown prevented the inhibitory effect of metformin on GH-stimulated PDK4 expression. SHP directly inhibited STAT5 association on the PDK4 gene promoter. Metformin inhibits GH-induced PDK4 expression and metabolites via an AMPK-SHP–dependent pathway. The metformin-AMPK-SHP network may provide a novel therapeutic approach for the treatment of hepatic metabolic disorders induced by the GH-mediated pathway.

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.

The amount of acoustic data gathered from the acoustic data gathering system is increased dramatically as the acoustic data gathering system become various and highly effective. It is needed to transmit this acoustic data to analysis environment for precise analysis. In this gathering/analysis system, it is also needed the stable transmitting as well as highly perfect security. But the existing system using the conveying method needs a lot of time. In case of using networks, the low speed networking vulnerable in the stable transmitting and the information security is impossible to materialize. In this paper, I would like to propose a transmitting and management system sending a massive gathering acoustic data in the unsecurity and low speed networking environment. The implemented system is to transmit the acoustic data safely in low speed networking environment and secure the acoustic data from various threats.

SHP (small heterodimer partner; NR0B2) is an atypical orphan NR (nuclear receptor) that functions as a transcriptional co-repressor by interacting with a diverse set of NRs and transcriptional factors. HNF-6 (hepatocyte nuclear factor-6) is a key regulatory factor in pancreatic development, endocrine differentiation and the formation of the biliary tract, as well as glucose metabolism. In this study, we have investigated the function of SHP as a putative repressor of HNF-6. Using transient transfection assays, we have shown that SHP represses the transcriptional activity of HNF-6. Confocal microscopy revealed that both SHP and HNF-6 co-localize in the nuclei of cells. SHP physically interacted with HNF-6 in protein–protein association assays in vitro . EMSAs (electrophoretic mobility-shift assays) and ChIP (chromatin immunoprecipitation) assays demonstrated that SHP inhibits the DNA-binding activity of HNF-6 to an HNF-6-response element consensus sequence, and the HNF-6 target region of the endogenous G6Pase (glucose 6-phosphatase) promoter respectively. Northern blot analysis of HNF-6 target genes in cells infected with adenoviral vectors for SHP and SHP siRNAs (small inhibitory RNAs) indicated that SHP represses the expression of endogenous G6Pase and PEPCK (phosphoenolpyruvate carboxykinase). Our results suggest that HNF-6 is a novel target of SHP in the regulation of gluconeogenesis. Abbreviations: Ad-SHP, adenoviral vector encoding full-length human SHP; Ad-siSHP, adenoviral vector encoding SHP siRNA; AF domain, activation function domain; AR, androgen receptor; CBP, CREB (cAMP-response-element-binding protein)-binding protein; ChIP, chromatin immunoprecipitation; CMV, cytomegalovirus; DBD, DNA-binding domain; DMEM, Dulbecco's modified Eagle's medium; ECL, enhanced chemiluminescence; EMSA, electrophoretic mobility-shift assay; ER, oestrogen receptor; FBS, fetal bovine serum; G6Pase, glucose 6-phosphatase; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; GR, glucocorticoid receptor; GST, glutathione transferase; HA, haemaglutinin; HDAC, histone deacetylase; HEK-293 cells, human embryonic kidney-293 cells; HEK-293T cells, HEK-293 cells expressing the large T-antigen of SV40 (simian virus 40); HNF, hepatocyte nuclear factor; LBD, ligand-binding domain; MOI, multiplicity of infection; NR, nuclear receptor; OATP, organic anion transporting polypeptide; PEPCK, phosphoenolpyruvate carboxykinase; PKA, protein kinase A; PGC, PPARγ co-activator; PPAR, peroxisome-proliferator-activated receptor; RT–PCR, reverse transcription–PCR; SHP, small heterodimer partner; siRNA, small inhibitory RNA; TNT, transcription and translation

Hepcidin is a peptide hormone secreted in the liver and plays a key role in maintaining iron homeostasis. Here, we demonstrate that B-cell translocation gene 2 (BTG2) is a key player in hepatic hepcidin regulation via induction of Yin Yang 1 (YY1). Hepatic hepcidin gene expression significantly enhanced by fasting states and glucagon exposure led to induction of gluconeogenic gene expression, and elevated serum hepcidin production in mice. Notably, overexpression of BTG2 using adenoviral system (Ad-BTG2) significantly elevated serum hepcidin levels via a significant induction of YY1 gene transcription. Immunoprecipitation studies demonstrated that BTG2 physically interacted with YY1 and recruited on the hepcidin gene promoter. Finally, ablation of hepatic BTG2 gene by gene silencing markedly attenuated the elevation of serum hepcidin production along with YY1 and hepcidin mRNA expression in fasting state. Likewise, forskolin (FSK)-stimulated hepcidin promoter activity was dramatically disrupted by endogenous BTG2 knockdown. Overall, our current study provides a novel molecular mechanism of BTG2-mediated induction of hepcidin gene expression, thereby contributing to a better understanding of the hepatic hepcidin production involved in iron homeostasis.

The orphan receptor small heterodimer partner (SHP; NROB2) is a transcriptional repressor that inhibits nuclear receptor signaling in diverse metabolic pathways. Here, we report that SHP−/− mice exhibited hypoinsulinemia with age, which was associated with increased peripheral insulin sensitivity and increased response of isolated islets to glucose stimulation, yet maintain normal levels of blood glucose. Deficiency in SHP function resulted in up-regulation of glucose transporter 4 mRNA and glucose uptake in muscles, and overexpression of SHP in C2C12 cells inhibited both basal and peroxisomal proliferator-activated receptor γ (PPARγ) coactivator-1α-stimulated glucose transporter 4 expression and glucose uptake. SHP−/− hepatocytes showed markedly decreased basal glucose production in cultures, and SHP−/− livers had increased glycogen stores and were more sensitive to insulin inhibition of glucose output, which were concomitant with decreased expression for PPARγ1, fatty acid translocase, glucose-6-phospha...

Vascular inflammation induced by the proinflammatory cytokine/NF-kappaB pathway is one of the key mechanisms in the development of neointimal hyperplasia. Accumulating evidence suggests that a recently identified chemokine, fractalkine, is involved in arterial inflammation and atherogenesis. However, no study has examined the expression of neointimal fractalkine and the effects of pharmacological agents on this process. The purposes of this study were to measure neointimal fractalkine expression in the rat carotid artery following balloon injury and to determine if alpha-lipoic acid (ALA) inhibits fractalkine expression and neointimal hyperplasia. Balloon injury of the rat carotid artery induced fractalkine expression in the medial as well as neointimal regions. ALA inhibited this expression and consequently prevented neoinitmal hyperplasia in a balloon-injured rat carotid artery. Additionally, ALA inhibited TNF-alpha-stimulated fractalkine expression in cultured vascular smooth muscle cells (VSMCs), a process which is mediated through the NF-kappaB pathway. In addition to fractalkine, ALA successfully inhibited TNF-alpha-stimulated expression of vascular cell adhesion molecule-1 and monocyte chemotactic protein-1 in cultured VSMCs. These data suggest that the cytokine-fractalkine system is involved in the pathogenesis of restenosis. The present study supports the possibility that ALA, which inhibits the NF-kappaB/fractalkine pathway, may be used to prevent neointimal hyperplasia after angioplasty or stenting.

We have investigated the temperature dependence of the intermolecular force between poly( N -isopropylacrylamide) (PNiPAM) grafted surface and bovine serum albumin (BSA) in phosphate buffer (pH 7.4) using atomic force microscopy at the nanonewton scale. These observations show that the interaction force is nearly zero below the phase transition temperature of PNiPAM and that it increases steeply during the phase transition. Since the PNiPAM chains are grafted onto the aminosilane ( γ -aminopropyltriethoxysilane)-treated silicon wafer, we measured the force–distance curve of BSA-immobilized tips for the bare and the aminosilane-treated silicon wafer. These surfaces show no temperature dependence and their values are different from those of the PNiPAM-grafted surfaces at 30 °C. The results indicate that the measured adhesion force is between the PNiPAM-grafted surface and the BSA-immobilized tip. Our studies on the intermolecular force between other surfaces (CH 3 - and COOH-terminated self-assembled monolayers) and the BSA-immobilized tip indicate that the variation in the intermolecular force between the PNiPAM surface and BSA with temperature can be attributed to the changes in the properties of the PNiPAM chains. From consideration of the PNiPAM phase transition mechanism, it is speculated that the intermolecular force between the PNiPAM-grafted surface and BSA would be affected by changes in the arrangement of the bound water molecules around the PNiPAM chain and by changes in the conformation (i.e., in the chain mobility) of the PNiPAM chain during the phase transition.

This report describes a novel method for preparing a thermally responsive poly(N-isopropylacrylamide) (PNiPAM) monolayer on a gold surface, and demonstrates the function of this monolayer in aqueous media. Thiol (–SH) terminated PNiPAM was synthesized by UV polymerization followed by hydrolysis, and a monolayer of this polymer (2.84±0.2 nm) was prepared on a gold substrate by simply dipping a precleaned gold plate into an aqueous solution of the PNiPAM. Cyclic voltametry and atomic force microscopy studies showed that the gold surface was well covered by the PNiPAM chains, and X-ray photoelectron spectroscopic data showed that this monolayer was chemisorbed on the gold surface. Studies of the water contact angle, protein interaction, and protein adsorption on the PNiPAM monolayer demonstrated that this monolayer shows a temperature dependence of the interfacial properties in aqueous media.

Background Extracellular signal-regulated kinases 1/2 (ERK1/2) make important contributions to allergic responses via their regulation of degranulation, eicosanoid production, and cytokine expression by mast cells, yet the mechanisms underlying their positive effects on FceRI-dependent signaling are not fully understood. Recently, we reported that mast cell activation and anaphylaxis are negatively regulated by AMP-activated protein kinase (AMPK). However, little is known about the relationship between ERK1/2-mediated positive and the AMPK-mediated negative regulation of FceRI signaling in mast cells. Objective We investigated possible interactions between ERK1/2 and AMPK in the modulation of mast cell signaling and anaphylaxis. Methods Wild-type or AMPK α 2 −/− mice, or bone marrow–derived mast cells obtained from these mice, were treated with either chemical agents or small interfering RNAs that modulated the activity or expression of ERK1/2 or AMPK to evaluate the functional interplay between ERK1/2 and AMPK in FceRI-dependent signaling. Results The ERK1/2 pathway inhibitor U0126 and the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside similarly inhibited FceRI-mediated mast cell signals in vitro and anaphylaxis in vivo . ERK1/2-specific small interfering RNA also mimicked this effect on FceRI signals. Moreover, AMPK α 2 knockdown or deficiency led to increased FceRI-mediated mast cell activation and anaphylaxis that were insensitive to U0126 or activator 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside, suggesting that the suppression of FceRI signals by the inhibition of the ERK1/2 pathway relies largely on AMPK activation. ERK1/2 controlled AMPK activity by regulating its subcellular translocation. Conclusions ERK1/2 ablated the AMPK-dependent negative regulatory axis, thereby activating FceRI signals in mast cells.

Low molecular weight fucoidan (LMWF) is widely used to treat metabolic disorders, but its physiologic effects have not been well determined. In the present study, we investigated the metabolic effects of LMWF in obese diabetic mice (leptin receptor–deficient db/db mice) and the underlying molecular mechanisms involved in endoplasmic reticulum (ER) stress-responsive L6 myotubes. The effect of LMWF-mediated AMP-activated protein kinase (AMPK) activation on insulin resistance via regulation of the ER stress-dependent pathway was examined in vitro and in vivo. In db/db mice, LMWF markedly reduced serum glucose, triglyceride, cholesterol, and low-density lipoprotein levels, and gradually reduced body weights by reducing lipid parameters. Furthermore, it effectively ameliorated glucose homeostasis by elevating glucose tolerance. In addition, the phosphorylation levels of AMPK and Akt were markedly reduced by ER stressor, and subsequently, glucose uptake and fatty acid oxidation were also reduced. However, these adverse effects of ER stress were significantly ameliorated by LMWF. Finally, in L6 myotubes, LMWF markedly reduced the ER stress-induced upregulation of the mammalian target of rapamycin–p70S61 kinase network and subsequently improved the action of insulin via AMPK stimulation. Our findings suggest that AMPK activation by LMWF could prevent metabolic diseases by controlling the ER stress-dependent pathway and that this beneficial effect of LMWF provides a potential therapeutic strategy for ameliorating ER stress-mediated metabolic dysfunctions.

The aim of the present study was to determine the effect of Tanshinone IIA (Tan IIA) on endoplasmic reticulum (ER) stress-induced insulin resistance in L6 myotubes and db/db mice. ER stress markers, RNA-activated protein kinase-like ER resident kinase (PERK), JNK, and AMPK activity were determined in tunicamycin-treated L6 myotubes. Insulin resistance was monitored using glucose uptake assays in vitro and blood glucose levels in vivo. Tan IIA clearly suppressed the phosphorylations of PERK and JNK and potentiated insulin-mediated Akt phosphorylation as well as glucose uptake via AMPK activation under ER stress. Furthermore, these effects are completely abrogated by siRNA-mediated knockdown of AMPK or LKB1. In addition, Tan IIA reduced blood glucose levels and body weights in db/db mice without altering food intake. These findings suggest that Tan IIA enhances insulin sensitivity and improves glucose metabolic disorders by increasing AMPK activity and attenuating ER stress-induced insulin resistance.

Cyclic AMP (cAMP) induces steroidogenic enzyme gene expression and stimulates testosterone production in Leydig cells. Phosphoenolpyruvate carboxykinase (PEPCK) is expressed in Leydig cells, but its role has not been defined. In this study, we found that PEPCK and glucose-6-phosphatase (Glc-6-Pase) are increased significantly following cAMP treatment of mouse Leydig cells. Moreover, cAMP treatment increased recruitment of the cAMP-response element-binding transcription factor and decreased recruitment of the corepressor DAX-1 on the pepck promoter. Furthermore, cAMP induced an increase in ATP that correlated with a decrease in phospho-AMP-activated protein kinase (AMPK). In contrast, knockdown or inhibition of PEPCK decreased ATP and increased phospho-AMPK. Treatment with an AMPK activator or overexpression of the constitutively active form of AMPK inhibited cAMP-induced steroidogenic enzyme promoter activities and gene expression. Liver receptor homolog-1 (LRH-1) was involved in cAMP-induced steroidogenic enzyme gene expression but was inhibited by AMPK activation in Leydig cells. Additionally, inhibition or knockdown of PEPCK and Glc-6-Pase decreased cAMP-mediated induction of steroidogenic enzyme gene expression and steroidogenesis. Finally, pubertal mouse (8-week-old) testes and human chorionic gonadotropin-induced prepubertal mouse testes showed increased PEPCK and Glc-6-Pase gene expression. Taken together, these results suggest that induction of PEPCK and Glc-6-Pase by cAMP plays an important role in Leydig cell steroidogenesis.

Hepatic gluconeogenesis is mediated by the network of transcriptional factors and cofactors. Here, we show that B-cell translocation gene-2 (BTG2) plays a crucial cofactor in hepatic gluconeogenesis via upregulation of the cyclic AMP (cAMP) response element binding (CREB) in hepatocytes. cAMP/dexamethasone (Dex) significantly increased BTG2 and other gluconeogenic genes such as Nur77, phosphoenolpyruvate carboxykinase (PEPCK), and glucose-6-phosphatase (G6Pase) in hepatocytes. In contrast, insulin treatment completely blocks their expressions. Interestingly, overexpression of BTG2 using adenoviral system (Ad-BTG2) significantly elevated hepatic glucose production via the increase of transcriptional activity and gene expression of CREB, PEPCK, and G6Pase in hepatocytes, suggesting that BTG2 is the key player on hepatic glucose production. Physiological interaction studies demonstrated that BTG2 correlated CREB recruitment on the PEPCK gene promoter via a direct interaction. Finally, knockdown of endogenous BTG2 expression markedly inhibits the cAMP/Dex-induced transcriptional activity of gluconeogenic genes and glucose production in hepatocytes. Overall, the present study provides us with a novel molecular mechanism of BTG2-mediated induction of hepatic gluconeogenesis and suggests that BTG2 plays an important role in hepatic glucose metabolism.

LIPINs have been reported to perform important roles in the regulation of intracellular lipid levels. Their mutations induce lipodystrophy, myoglobinuria, and inflammatory disorders. Recently, the phosphatidic acid phosphatase function of LIPINs has been associated with the perturbation of hepatic insulin receptor signaling via the diacylglycerol-mediated stimulation of PKCϵ activity. Here, we report that nuclear estrogen-related receptor (ERR) γ is a novel transcriptional regulator of LIPIN1. Overexpression of ERRγ significantly increased LIPIN1 expression in primary hepatocytes, whereas the abolition of ERRγ gene expression attenuated the expression of LIPIN1. Deletion and mutation analyses of the LIPIN1 promoter showed that ERRγ exerts its effect on the transcriptional regulation of LIPIN1 via ERRE1 of the LIPIN1 promoter, as confirmed by ChIP assay. We also determined that the gene transcription of LIPIN1 by ERRγ is controlled by the competition between PGC-1α and small heterodimer partner. Additionally, ERRγ leads to the induction of hepatic LIPIN1 expression and diacylglycerol production in vivo. Finally, an inverse agonist of ERRγ, GSK5182, restores the impaired insulin signaling induced by LIPIN1-mediated PKCϵ activation. Our findings indicate that the selective control of ERRγ transcriptional activity by its specific inverse agonist could provide a novel therapeutic approach to the amelioration of impaired hepatic insulin signaling induced by LIPIN1-mediated PKCϵ activation.

Metformin is an oral anti-diabetic drug of the biguanide class that is commonly used to treat type 2 diabetes mellitus. This study examined the molecular mechanism for the action of metformin on osteoblast differentiation. Metformin-induced mRNA expression of the osteogenic genes and small heterodimer partner (SHP) in MC3T3E1 cells were determined by RT-PCR and real-time PCR. Metformin increased significantly the expression of the key osteogenic genes, such as alkaline phosphatase (ALP), osteocalcin (OC) and bone sialoprotein (BSP) as well as SHP. Transient transfection assays were performed in MC3T3E1 cells to confirm the effects of metformin on SHP, OC and Runx2 promoter activities. Metformin increased the transcription of the SHP and OC genes, and the metformin effect was inhibited by dominant negative form of AMPK (DN-AMPK) or compound C (an inhibitor of AMPK). The adenoviral overexpression of SHP increased significantly the level of ALP staining and OC production. However, metformin did not have any significant effect on osteogenic gene expression, ALP staining and activity, and OC production in SHP null (SHP-/-) primary calvarial cells. Moreover, upstream stimulatory factor-1 (USF-1) specifically mediated metformin-induced SHP gene expression. In addition, metformin-induced AMPK activation increased the level of Runx2 mRNA and protein. However, USF-1 and SHP were not involved in metformin-induced Runx2 expression. Transient transfection and chromatin immunoprecipitation assays confirmed that metformin-induced SHP interacts physically and forms a complex with Runx2 on the osteocalcin gene promoter in MC3T3E1 cells. These results suggest that metformin may stimulate osteoblast differentiation through the transactivation of Runx2 via AMPK/USF-1/SHP regulatory cascade in mouse calvaria-derived cells.

Fatty liver is common in obese subjects with insulin resistance. Hepatic expression of sterol regulatory element binding protein-1c (SREBP-1c), which plays a major role in hepatic steatosis, is regulated by multiple factors, including insulin, adenosine monophosphate–activated protein kinase (AMPK), liver X receptors (LXRs), and specificity protein 1. Alpha-lipoic acid (ALA), a naturally occurring antioxidant, has been shown to decrease lipid accumulation in skeletal muscle by activating AMPK. Here we show that ALA decreases hepatic steatosis and SREBP-1c expression in rats on a high fat diet or given an LXR agonist. ALA increased AMPK phosphorylation in the liver and in cultured liver cells, and dominant-negative AMPK partially prevented ALA-induced suppression of insulin-stimulated SREBP-1c expression. ALA also inhibited DNA-binding activity and transcriptional activity of both specificity protein 1 and LXR. Conclusion: These results show that ALA prevents fatty liver disease through multiple mechanisms, and suggest that ALA can be used to prevent the development and progression of nonalcoholic fatty liver disease in patients with insulin resistance. (HEPATOLOGY 2008.)

Bisphenol A bis (2,3-dihydroxypropyl) ether (BADGE.2H(2)O) is a component of commercial liquid epoxy resins commonly used in the food-packing industry and in dental sealants. There is evidence that it has significant estrogenic activity. Nur77 plays a crucial role in the regulation of certain genes involved in LH-mediated steroidogenesis in testicular Leydig cells. It was previously demonstrated that Bisphenol A (BPA) stimulates Nur77 gene induction and steroidogenesis. In this study, we investigated the effects of BADGE.2H(2)O on Nur77 gene expression and steroidogenesis. Northern blot analysis showed that it increased the expression of Nur77 mRNA and protein, and transient transfection assays demonstrated that it increased the promoter activity and transactivation of Nur77. It also increased the expression of certain steroidogenic genes, such as StAR and 3 beta-HSD. Finally, over-expression of a dominant negative Nur77 cDNA via adenoviral infection reduced BADGE.2H(2)O-mediated progesterone biosynthesis. These results indicate that BADGE.2H(2)O disrupts testicular steroidogenesis by increasing Nur77 gene expression.

The highly developed endoplasmic reticulum (ER) structure of pancreatic β-cells is a key factor in β-cell function. Here we examined whether ER stress-induced activation of activating transcription factor (ATF)-6 impairs insulin gene expression via up-regulation of the orphan nuclear receptor small heterodimer partner (SHP; NR0B2), which has been shown to play a role in β-cell dysfunction. We examined whether ER stress decreases insulin gene expression, and this process is mediated by ATF6. A small interfering RNA that targeted SHP was used to determine whether the effect of ATF6 on insulin gene expression is mediated by SHP. We also measured the expression level of ATF6 in pancreatic islets in Otsuka Long Evans Tokushima Fatty rats, a rodent model of type 2 diabetes. High glucose concentration (30 mmol/liter glucose) increased ER stress in INS-1 cells. ER stress induced by tunicamycin, thapsigargin, or dithiotreitol decreased insulin gene transcription. ATF6 inhibited insulin promoter activity, whereas X-box binding protein-1 and ATF4 did not. Adenovirus-mediated overexpression of active form of ATF6 in INS-1 cells impaired insulin gene expression and secretion. ATF6 also down-regulated pancreatic duodenal homeobox factor-1 and RIPE3b1/MafA gene expression and repressed the cooperative action of pancreatic duodenal homeobox factor-1, RIPE3b1/MafA, and β-cell E box transactivator 2 in stimulating insulin transcription. The ATF6-induced suppression of insulin gene expression was associated with up-regulation of SHP gene expression. Finally, we found that expression of ATF6 was increased in the pancreatic islets of diabetic Otsuka Long Evans Tokushima Fatty rats, compared with their lean, nondiabetic counterparts, Long-Evans Tokushima Otsuka rats. Collectively, this study shows that ER stress-induced activation of ATF6 plays an important role in the development of β-cell dysfunction.