B-cell translocation gene 2 regulates hepatic glucose homeostasis via induction of orphan nuclear receptor Nur77 in diabetic mouse model

Follicular fluid exosomes inhibit expression of BTG2 and promote glucose uptake in granulosa cells by delivering miR-21-5p

Glucose metabolism in granulosa cells (GCs) is essential for follicle development and oocyte maturation. Porcine follicular fluid exosomes promote the proliferation of porcine GCs and the synthesis of steroid hormones. However, their role in regulating glucose uptake in GCs is unclear. The objective of this study was to elucidate the effects of porcine follicular fluid exosomes on glucose uptake in porcine GCs and the intrinsic mechanisms involved. First, transcriptome sequencing revealed that glucose metabolism-related pathways were altered in GCs treated with follicular fluid exosomes. Next, in vitro culture experiments showed that glucose uptake was increased and the IRS1/AKT signaling pathway was activated in GCs after treatment with follicular fluid exosomes. Finally, miRNA sequencing of follicular fluid exosomes revealed that miR-21-5p was the most abundant miRNA. Subsequent investigations indicated that miR-21-5p promoted glucose uptake in GCs by targeting BTG2, which activated the IRS1/AKT signaling pathway. In conclusion, the findings of this study indicate that porcine follicular fluid exosomes promote glucose uptake in porcine GCs by delivering miR-21-5p, which inhibits the expression of BTG2, activating the IRS1/AKT signaling pathway.

The impact of vaccine-linked chemotherapy on liver health in a mouse model of chronic Trypanosoma cruzi infection

BACKGROUND

Chagas disease, chronic infection with Trypanosoma cruzi, mainly manifests as cardiac disease. However, the liver is important for both controlling parasite burdens and metabolizing drugs. Notably, high doses of anti-parasitic drug benznidazole (BNZ) causes liver damage. We previously showed that combining low dose BNZ with a prototype therapeutic vaccine is a dose sparing strategy that effectively reduced T. cruzi induced cardiac damage. However, the impact of this treatment on liver health is unknown. Therefore, we evaluated several markers of liver health after treatment with low dose BNZ plus the vaccine therapy in comparison to a curative dose of BNZ.

METHODOLOGY

Female BALB/c mice were infected with a bioluminescent T. cruzi H1 clone for approximately 70 days, then randomly divided into groups of 15 mice each. Mice were treated with a 25mg/kg BNZ, 25μg Tc24-C4 protein/ 5μg E6020-SE (Vaccine), 25mg/kg BNZ followed by vaccine, or 100mg/kg BNZ (curative dose). At study endpoints we evaluated hepatomegaly, parasite burden by quantitative PCR, cellular infiltration by histology, and expression of B-cell translocation gene 2(BTG2) and Peroxisome proliferator-activated receptor alpha (PPARα) by RT-PCR. Levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were quantified from serum.

RESULTS

Curative BNZ treatment significantly reduced hepatomegaly, liver parasite burdens, and the quantity of cellular infiltrate, but significantly elevated serum levels of ALT, AST, and LDH. Low BNZ plus vaccine did not significantly affect hepatomegaly, parasite burdens or the quantity of cellular infiltrate, but only elevated ALT and AST. Low dose BNZ significantly decreased expression of both BTG2 and PPARα, and curative BNZ reduced expression of BTG2 while low BNZ plus vaccine had no impact.

CONCLUSIONS

These data confirm toxicity associated with curative doses of BNZ and suggest that while dose sparing low BNZ plus vaccine treatment does not reduce parasite burdens, it better preserves liver health.

Enhancement of the SESN2-SHP cascade by melatonin ameliorates hepatic gluconeogenesis by inhibiting the CRBN-BTG2-CREBH signaling pathway

Melatonin is involved in the regulation of various biological functions. Here, we explored a novel molecular mechanism by which the melatonin-induced sestrin2 (SESN2)-small heterodimer partner (SHP) signaling pathway protects against fasting- and diabetes-mediated hepatic glucose metabolism. Various key gene expression analyses were performed and multiple metabolic changes were assessed in liver specimens and primary hepatocytes of mice and human participants. The expression of the hepatic cereblon (CRBN) and b-cell translocation gene 2 (BTG2) genes was significantly increased in fasting mice, diabetic mice, and patients with diabetes. Overexpression of Crbn and Btg2 increased hepatic gluconeogenesis by enhancing cyclic adenosine monophosphate (cAMP)-responsive element-binding protein H (CREBH), whereas this phenomenon was prominently ablated in Crbn null mice and Btg2-silenced mice. Interestingly, melatonin-induced SESN2 and SHP markedly reduced hepatic glucose metabolism in diabetic mice and primary hepatocytes, and this protective effect of melatonin was strikingly reversed by silencing Sesn2 and Shp. Finally, the melatonin-induced SESN2-SHP signaling pathway inhibited CRBN- and BTG2-mediated hepatic gluconeogenic gene transcription via the competition of BTG2 and the interaction of CREBH. Mitigation of the CRBN-BTG2-CREBH axis by the melatonin-SESN2-SHP signaling network may provide a novel therapeutic strategy to treat metabolic dysfunction due to diabetes.

The impact of vaccine-linked chemotherapy on liver health in a mouse model of chronic Trypanosoma cruzi infection

Background

Chagas disease, chronic infection with Trypanosoma cruzi, mainly manifests as cardiac disease. However, the liver is important for both controlling parasite burdens and metabolizing drugs. Notably, high doses of anti-parasitic drug benznidazole (BNZ) causes liver damage. We previously showed that combining low dose BNZ with a prototype therapeutic vaccine is a dose sparing strategy that effectively reduced T. cruzi induced cardiac damage. However, the impact of this treatment on liver health is unknown. Therefore, we evaluated several markers of liver health after treatment with low dose BNZ plus the vaccine therapy in comparison to a curative dose of BNZ.

Methodology

Female BALB/c mice were infected with a bioluminescent T. cruzi H1 clone for approximately 70 days, then randomly divided into groups of 15 mice each. Mice were treated with a 25mg/kg BNZ, 25μg Tc24-C4 protein/5μg E6020-SE (Vaccine), 25mg/kg BNZ followed by vaccine, or 100mg/kg BNZ (curative dose). At study endpoints we evaluated hepatomegaly, parasite burden by quantitative PCR, cellular infiltration by histology, and expression of B-cell translocation gene 2(BTG2) and Peroxisome proliferator-activated receptor alpha (PPARα) by RT-PCR. Levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were quantified from serum.

Results

Curative BNZ treatment significantly reduced hepatomegaly, liver parasite burdens, and the quantity of cellular infiltrate, but significantly elevated serum levels of ALT, AST, and LDH. Low BNZ plus vaccine did not significantly affect hepatomegaly, parasite burdens or the quantity of cellular infiltrate, but only elevated ALT and AST. Low dose BNZ significantly decreased expression of both BTG2 and PPARα, and curative BNZ reduced expression of BTG2 while low BNZ plus vaccine had no impact.

Conclusions

These data confirm toxicity associated with curative doses of BNZ and suggest that the dose sparing low BNZ plus vaccine treatment better preserves liver health.

Proper regulation of β-adrenergic signal requires Btg2 gene for lipolysis and thermogenesis in response to starvation or cold acclimation in female mice

Mammals maintain constant body temperature in cold environment by activating thermogenesis via adrenergic/protein kinase A (PKA) signaling. B-cell translocation gene 2 (BTG2^/Tis21), induced by PKA signaling, regulates glucose and lipid metabolism in liver, yet its role in lipolysis and in thermogenesis is not explored. Here, Btg2-knockout (KO) mice failed to maintain body temperature under starvation, or in cold acclimation. And norepinephrine-induced thermogenic response was turned off earlier in the KO mice. Gender specifically, gonadal white adipose tissues (gWAT) of female-KO were very active in lipolysis in fed state, however, the fat degradation was diminished upon fasting or cold acclimation. Also, insulin sensitivity was increased in female-KO, but not in male-KO mice, along with the low bone mineral density and small brown adipose tissues (BAT). In the mechanistic aspect, expressions of UCP1 and lipases (LPL, ATGL, HSL) in gWAT of female-KO mice were significantly reduced in response to adrenergic signals. Here, we present some data that Btg2 gene is essential for properly respond to β-adrenergic signals, and plays as a negative regulator of insulin signaling in female mice.

Adipose mesenchymal stem cell-derived exosomal microRNAs ameliorate polycystic ovary syndrome by protecting against metabolic disturbances

Polycystic ovary syndrome (PCOS) is the most common endocrine and metabolic disorder in women of childbearing age. Adipose mesenchymal stem cells (AMSCs) secrete cytokines involved in the regulation of metabolism and immunity. However, it remains unclear whether exosomes secreted by AMSCs (AMSC-EXOs) can rescue the polycystic phenotype and metabolic dysfunction in PCOS ovaries. Here, we show that AMSC-EXOs can protect against metabolic disturbances, ameliorate ovarian polycystic, and improve fertility in a rat model of PCOS. AMSC-EXOs inhibited the expression of B-cell translocation gene 2 by transferring miR-21-5p to the livers of rats with PCOS, thus activating the IRS1/AKT pathway and increasing hepatic metabolism. The role of AMSC-EXOs in transferring miRNAs to the liver to improve metabolic dysfunction in PCOS and reproduction by rescuing a non-coding RNA pathway was also discovered. This study provides a theoretical basis for the use of rat adipose stem cells and their secreted exosomes to treat PCOS.

Exogenous insulin promotes the expression of B-cell translocation gene 1 and 2 in chicken pectoralis

B-cell translocation genes (BTG) have been proved to play important roles in carbohydrate metabolism through modifying insulin homeostasis and glucose metabolism. This study, therefore, was conducted to investigate the effects of exogenous insulin on the expression of BTG1 and BTG2 in chickens. Twenty-four-day-old broilers and layers were fasted for 16 h and randomly assigned to insulin treatment group (subcutaneously injected with 5 IU/kg body weight) or control group (received an equivalent volume of phosphate-buffered saline). Blood glucose concentration was measured, and it showed that the blood glucose concentrations in the layers were significantly (P < 0.05) higher than that in the broilers under fasting state. Response to exogenous insulin, the blood glucose concentrations were greatly reduced in both breeds. Of note, the blood glucose concentration restored to 62% of the basal state at 240 min (P < 0.05) after insulin stimulation in layers, whereas it was still in low level until 240 min in broilers (under fast state). Tissue profiling revealed that both BTG1 and BTG2 were abundantly expressed in the skeletal muscles of broilers. A negative correlation was observed between blood glucose and BTG1 (ρ = −0.289, P = 0.031) /BTG2 (ρ = −0.500, P < 0.001) in pectoralis, and BTG1 (ρ = −0.462, P < 0.001) in pancreas. As blood glucose decreased due to exogenous insulin administration (under fast state), the expression of both BTG1 and BTG2 notably upregulated in birds’ pectoralis at 120 min and/or 240 min, meanwhile pancreas BTG1 was also upregulated. Re-feeding at 120 min elevated the blood glucose and reduced the expression of BTG genes in pectoralis generally. In addition, the change of BTG1 and BTG2 expression showed distinct difference between layers and broilers at 120 min and 240 min after insulin stimulation in pectoralis, pancreas and heart tissue; even after re-feeding at 120 min, BTG2 expression at 240 min after insulin injection was downregulated in the pectoralis of layers, while it was upregulated in that broilers. Collectively, these results indicated that response to exogenous insulin, chicken blood glucose exhibited breed-specific dynamic change, and meanwhile the expressions of both BTG1 and BTG2 genes in chickens were significantly altered by exogenous insulin in a breed- and tissue-specific manner. BTG1 and BTG2 genes may negatively regulate bird's blood glucose by promoting the glucose uptake corporately in pectoralis, and through regulating the insulin secretion in pancreas (especially BTG1).

Knockout of Nur77 Leads to Amino Acid, Lipid, and Glucose Metabolism Disorders in Zebrafish

Orphan nuclear receptor Nur77 has been reported to be implicated in a diverse range of metabolic processes, including carbohydrate metabolism and lipid metabolism. However, the detailed mechanism of Nur77 in the regulation of metabolic pathway still needs to be further investigated. In this study, we created a global nur77 knockout zebrafish model by CRISPR/Cas9 technique, and then performed whole-organism RNA sequencing analysis in wildtype and nur77-deficient zebrafish to dissect the genetic changes in metabolic-related pathways. We found that many genes involved in amino acid, lipid, and carbohydrate metabolism changed by more than twofold. Furthermore, we revealed that nur77^-/- mutant displayed increased total cholesterol (TC) and triglyceride (TG), alteration in total amino acids, as well as elevated glucose. We also demonstrated that the elevated glucose was not due to the change of glucose uptake but was likely caused by the disorder of glycolysis/gluconeogenesis and the impaired β-cell function, including downregulated insb expression, reduced β-cell mass, and suppressed insulin secretion. Importantly, we also verified that targeted expression of Nur77 in the β cells is sufficient to rescue the β-cell defects in global nur77^-/- larvae zebrafish. These results provide new information about the global metabolic network that Nur77 signaling regulates, as well as the role of Nur77 in β-cell function.

Growth hormone promotes hepatic gluconeogenesis by enhancing BTG2-YY1 signaling pathway

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.

Identification of the Differentially Expressed Genes Involved in the Synergistic Neurotoxicity of an HIV Protease Inhibitor and Methamphetamine

BACKGROUND

The abuse of psychostimulants such as methamphetamine (METH) is common in human immunodeficiency virus (HIV)-infected individuals. Acquired immunodeficiency syndrome (AIDS) patients taking METH and antiretroviral drugs could suffer severe neurologic damage and cognitive impairment.

OBJECTIVE

To reveal the underlying neuropathologic mechanisms of an HIV protease inhibitor (PI) combined with METH, growth-inhibition tests of dopaminergic cells and RNA sequencing were performed.

METHODS

A combination of METH and PI caused more growth inhibition of dopaminergic cells than METH alone or a PI alone. Furthermore, we identified differentially expressed gene (DEG) patterns in the METH vs. untreated cells (1161 genes), PI vs. untreated cells (16 genes), METH-PI vs. PI (3959 genes), and METH-PI vs. METH groups (14 genes).

RESULTS

The DEGs in the METH-PI co-treatment group were verified in the brains of a mouse model using quantitative polymerase chain reaction and were involved mostly in the regulatory functions of cell proliferation and inflammation.

CONCLUSION

Such identification of key regulatory genes could facilitate the study of their neuroprotective potential in the users of METH and PIs.

Function of Nr4a Orphan Nuclear Receptors in Proliferation, Apoptosis and Fuel Utilization Across Tissues

The Nr4a family of nuclear hormone receptors is composed of three members-Nr4a1/Nur77, Nr4a2/Nurr1 and Nr4a3/Nor1. While currently defined as ligandless, these transcription factors have been shown to regulate varied processes across a host of tissues. Of particular interest, the Nr4a family impinge, in a tissue dependent fashion, on cellular proliferation, apoptosis and fuel utilization. The regulation of these processes occurs through both nuclear and non-genomic pathways. The purpose of this review is to provide a balanced perspective of the tissue specific and Nr4a family member specific, effects on cellular proliferation, apoptosis and fuel utilization.

B-cell translocation gene 2 enhances fibroblast growth factor 21 production by inducing Kruppel-like factor 15

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.

Screening for insulin-independent pathways that modulate glucose homeostasis identifies androgen receptor antagonists

Pathways modulating glucose homeostasis independently of insulin would open new avenues to combat insulin resistance and diabetes. Here, we report the establishment, characterization, and use of a vertebrate ‘insulin-free’ model to identify insulin-independent modulators of glucose metabolism. insulin knockout zebrafish recapitulate core characteristics of diabetes and survive only up to larval stages. Utilizing a highly efficient endoderm transplant technique, we generated viable chimeric adults that provide the large numbers of insulin mutant larvae required for our screening platform. Using glucose as a disease-relevant readout, we screened 2233 molecules and identified three that consistently reduced glucose levels in insulin mutants. Most significantly, we uncovered an insulin-independent beneficial role for androgen receptor antagonism in hyperglycemia, mostly by reducing fasting glucose levels. Our study proposes therapeutic roles for androgen signaling in diabetes and, more broadly, offers a novel in vivo model for rapid screening and decoupling of insulin-dependent and -independent mechanisms.

Diabetes is a disease that affects the ability of the body to control the level of sugar in the blood. Individuals with diabetes are unable to make a hormone called insulin – which normally stimulates certain cells to absorb sugar from the blood – or their cells are less able to respond to this hormone. Most treatments for diabetes involve replacing the lost insulin or boosting the hormone’s activity in the body. However, these treatments can also cause individuals to gain weight or become more resistant to insulin, making it harder to control blood sugar levels.

In addition to insulin, several other factors regulate the levels of sugar in the blood and some of them may operate independently of insulin. However, little is known about such factors because it is impractical to carry out large-scale screens to identify drugs that target them in humans or mice, which are often used as experimental models for human biology.

To overcome this challenge, Mullapudi et al. turned to another animal known as the zebrafish and generated mutant fish that lack insulin. The mutant zebrafish had similar problems with regulating sugar levels as those observed in humans and mice with diabetes. This observation suggests that insulin is just as important in zebrafish as it is in humans and other mammals.

The mutant zebrafish did not survive into adulthood, and so Mullapudi et al. transplanted healthy tissue into the zebrafish to allow them to produce enough insulin to survive. These adult zebrafish produced many offspring that still carried the insulin mutation. Mullapudi et al. used these mutant offspring to screen over 2,000 drugs for their ability to decrease blood sugar levels in the absence of insulin. The screen identified three promising candidate drugs, including a molecule that interferes with a receptor for a signal known as androgen.

These findings will help researchers investigate new ways to treat diabetes. In the future, the screening approach developed by Mullapudi et al. could be adapted to search for new drugs to treat other human metabolic conditions.

Lack of 17β-estradiol reduces sensitivity to insulin in the liver and muscle of male mice

The importance of estrogens for glucose homeostasis has been demonstrated by clinical, pharmacological, and experimental studies. Male mice lacking the aromatase gene (ArKO mice), which encodes an enzyme involved in estrogen synthesis, develop glucose- and insulin-intolerance. However, it remains unclear whether insulin signaling is actually impaired in the liver and muscle of ArKO mice. We examined the effects of estrogen-deficiency on insulin signaling by quantifying phosphorylation levels of protein kinase B (Akt) in the liver and muscle and by examining the expression levels of insulin-target genes in the liver. Insulin administration enhanced phosphorylation levels of Akt in the liver and muscle of wild-type (WT) mice, ArKO mice, and ArKO mice supplemented with 17β-estradiol (E2), but insulin was less effective in ArKO mice. Gene expression analysis revealed that alterations induced by insulin in WT liver were also observed in ArKO liver, but the degree of altered expression in a subset of genes was smaller in ArKO mice than in WT mice. E2 supplementation improved the insulin responses of some genes in ArKO mice. Thus, these findings suggest that insulin signaling in the liver and muscle of ArKO mice is less efficient than in WT mice, which contributes to whole-body glucose intolerance in ArKO mice.

PPARα-Target Gene Expression Requires TIS21/BTG2 Gene in Liver of the C57BL/6 Mice under Fasting Condition

The TIS21/BTG2/PC3 gene belongs to the antiproliferative gene (APRO) family and exhibits tumor suppressive activity. However, here we report that TIS21 controls lipid metabolism, rather than cell proliferation, under fasting condition. Using microarray analysis, whole gene expression changes were investigated in liver of TIS21 knockout (TIS21-KO) mice after 20 h fasting and compared with wild type (WT). Peroxisome proliferator-activated receptor alpha (PPARα) target gene expression was almost absent in contrast to increased lipid synthesis in the TIS21-KO mice compared to WT mice. Immunohistochemistry with hematoxylin and eosin staining revealed that lipid deposition was focal in the TIS21-KO liver as opposed to the diffuse and homogeneous pattern in the WT liver after 24 h starvation. In addition, cathepsin E expression was over 10 times higher in the TIS21-KO liver than that in the WT, as opposed to the significant reduction of thioltransferase in both adult and fetal livers. At present, we cannot account for the role of cathepsin E. However, downregulation of glutaredoxin 2 thioltransferase expression might affect hypoxic damage in the TIS21-KO liver. We suggest that the TIS21/BTG2 gene might be essential to maintain energy metabolism and reducing power in the liver under fasting condition.

Pituitary NR4A1 is negatively regulated by thyroid hormone without direct binding of thyroid hormone receptors on the gene

We previously reported that TRH stimulated pituitary TSHβ gene expression via an immediate increase in NR4A1 in thyrotrophs. We demonstrated that NR4A1 mRNA levels are regulated by thyroid hormone. Pituitary NR4A1 mRNA levels were decreased in mice injected with L-T4. NR4A1 promoter activity was increased by the overexpression of TRβs, and these increases were decreased by T3, and the -27∼+152 bp region was responsible for these changes in vitro. An EMSA showed the lack of TRβs-isoforms binding, and a ChIP assay demonstrated the recruitment of TRβs and NCoR in the -147∼+148 bp region in the absence of T3, whereas T3 induced their release. Experiments on the overexpression and knockdown of NCoR, and using the mutant TRs supported the involvement of NCoR in the TR-induced stimulation. These results demonstrate that thyroid hormone down-regulated basal NR4A1 mRNA levels in the pituitary, and the direct binding of TR was not required.

Regulatory effects of berberine on microRNome in Cancer and other conditions

Berberine (BBR) is an isoquinoline alkaloid found in different plant families such as Berberidaceae, Ranunculaceae, and Papaveraceae. BBR is well-known for its anti-inflammatory, lipid-modifying, anticancer, anti-diabetic, antibacterial, antiparasitic and fungicide activities. Multiple pharmacological actions of BBR stem from different molecular targets of this phytochemical. MicroRNAs (miRs) are single-stranded, evolutionary conserved, small non-coding RNA molecules with a length of 19-23 nucleotides that are involved in RNA silencing and post-transcriptional regulation of gene expression through binding to the 3'-untranslated region (3'UTR) of target mRNA. MiRs emerged as important regulatory elements in almost all biological processes like cell proliferation, apoptosis, differentiation and organogenesis, and numerous human diseases such as cancer and diabetes. BBR was shown to regulate the expression of miRs in several diseases. Here, we reviewed the target miRs of BBR and the relevance of their modulation for the potential treatment of serious human diseases like multiple myeloma, hepatocellular carcinoma, colorectal cancer, gastric cancer, ovarian cancer and glioblastoma. The role of miR regulation in the putative anti-diabetic effects of BBR is discussed, as well.

Melatonin ameliorates alcohol-induced bile acid synthesis by enhancing miR-497 expression

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.

PCK1 expression is correlated with the plasma glucose level in the duck

Phosphoenolpyruvate carboxykinase 1 (soluble) (PCK1) is a key gene in gluconeogenesis and glyceroneogenesis. Although its functions have been extensively studied in mice, bats and humans, little is known in ducks. Here, PCK1 functions were studied using a duck domestication model and a 48-h fasting experiment. We found PCK1 expression significantly decreased in two breeds of domestic ducks (Jinyun Pockmark ducks and Cherry Valley ducks) as compared with wild ducks (Anas platyrhynchos). Simultaneously, plasma levels of glucose, triglycerides and free fatty acid in domestic ducks were lower than in wild ducks. When compared with fed ducks, the plasma triglyceride level was observed to be significantly decreased, while the glucose and free fatty acid levels remained constant in 48-h fasting ducks. The expression analysis of gluconeogenic genes revealed that fructose-1,6-bisphosphatase genes (FBP1 and FBP2) and the glucose-6-phosphatase gene (G6PC2) were not changed, whereas PCK1 was significantly upregulated. In addition, the reported regulators of PCK1, including forkhead box A2 (FOXA2) gene and orphan nuclear receptor NR4A family genes (NR4A1, NR4A2 and NR4A3), exhibited similar expression levels between 48-h fasting ducks and fed ducks, suggesting that PCK1 is not regulated by these genes in the duck under fasting conditions. In conclusion, PCK1 expression may affect plasma levels of glucose, triglycerides and free fatty acid during the duck domestication process. This work demonstrates for the first time in duck that PCK1 is a key gene in maintaining plasma glucose homeostasis during fasting and that the upregulated expression of PCK1 may be responsible for constant plasma free fatty acid level by the glyceroneogenesis process.

The NR4A subfamily of nuclear receptors: potential new therapeutic targets for the treatment of inflammatory diseases

INTRODUCTION

Prolonged inflammatory response contributes to the pathogenesis of chronic disease-related disturbances. Among nuclear receptors (NRs), the orphan NR4A subfamily, which includes Nur77 (NR4A1), Nurr1 (NR4A2) and NOR1 (NR4A3), has recently emerged as a therapeutic target for the treatment of inflammation. Areas covered: This review focuses on the capacity of NR4A receptors to counter-regulate the development of the inflammatory response, with a special focus on the molecular transrepression mechanisms. Expert opinion: Recent studies have highlighted the role of NR4A receptors as significant regulators of the inflammatory response. NR4A receptors are rapidly induced by inflammatory stimuli, thus suggesting that they are required for the initiation of inflammation. Nevertheless, NR4A anti-inflammatory properties indicate that this acute regulation could be a protective reaction aimed at resolving inflammation in the later stages. Therefore, NR4A receptors are involved in a negative feedback mechanism to maintain the inflammatory balance. However, the underlying mechanisms are not entirely clear. Only a small number of NR4A-target genes have been identified, and the transcriptional repression mechanisms are only beginning to emerge. Despite further research is needed to fully understand the role of NR4A receptors in inflammation, these NRs should be considered as targets for new therapeutic approaches to inflammatory diseases.

Nur77-deficiency in bone marrow-derived macrophages modulates inflammatory responses, extracellular matrix homeostasis, phagocytosis and tolerance

Background

The nuclear orphan receptor Nur77 (NR4A1, TR3, or NGFI-B) has been shown to modulate the inflammatory response of macrophages. To further elucidate the role of Nur77 in macrophage physiology, we compared the transcriptome of bone marrow-derived macrophages (BMM) from wild-type (WT) and Nur77-knockout (KO) mice.

Results

In line with previous observations, SDF-1α (CXCL12) was among the most upregulated genes in Nur77-deficient BMM and we demonstrated that Nur77 binds directly to the SDF-1α promoter, resulting in inhibition of SDF-1α expression. The cytokine receptor CX3CR1 was strongly downregulated in Nur77-KO BMM, implying involvement of Nur77 in macrophage tolerance. Ingenuity pathway analyses (IPA) to identify canonical pathways regulation and gene set enrichment analyses (GSEA) revealed a potential role for Nur77 in extracellular matrix homeostasis. Nur77-deficiency increased the collagen content of macrophage extracellular matrix through enhanced expression of several collagen subtypes and diminished matrix metalloproteinase (MMP)-9 activity. IPA upstream regulator analyses discerned the small GTPase Rac1 as a novel regulator of Nur77-mediated gene expression. We identified an inhibitory feedback loop with increased Rac1 activity in Nur77-KO BMM, which may explain the augmented phagocytic activity of these cells. Finally, we predict multiple chronic inflammatory diseases to be influenced by macrophage Nur77 expression. GSEA and IPA associated Nur77 to osteoarthritis, chronic obstructive pulmonary disease, rheumatoid arthritis, psoriasis, and allergic airway inflammatory diseases.

Conclusions

Altogether these data identify Nur77 as a modulator of macrophage function and an interesting target to treat chronic inflammatory disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2469-9) contains supplementary material, which is available to authorized users.

Nuclear receptor 4A (NR4A) family - orphans no more

The orphan nuclear receptors NR4A1, NR4A2 and NR4A3 are immediate early genes induced by multiple stressors, and the NR4A receptors play an important role in maintaining cellular homeostasis and disease. There is increasing evidence for the role of these receptors in metabolic, cardiovascular and neurological functions and also in inflammation and inflammatory diseases and in immune functions and cancer. Despite the similarities of NR4A1, NR4A2 and NR4A3 and their interactions with common cis-genomic elements, they exhibit unique activities and cell-/tissue-specific functions. Although endogenous ligands for NR4A receptors have not been identified, there is increasing evidence that structurally-diverse synthetic molecules can directly interact with the ligand binding domain of NR4A1 and act as agonists or antagonists, and ligands for NR4A2 and NR4A3 have also been identified. Since NR4A receptors are key factors in multiple diseases, there are opportunities for the future development of NR4A ligands for clinical applications in treating multiple health problems including metabolic, neurologic and cardiovascular diseases, other inflammatory conditions, and cancer.

B-cell translocation gene 2 promotes hepatic hepcidin production via induction of Yin Yang 1

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.