Transcription factor glucocorticoid modulatory element-binding protein 1 promotes hepatocellular carcinoma progression by activating Yes-associate protein 1

BACKGROUND Glucocorticoid modulatory element-binding protein 1(GMEB1),which has been identified as a transcription factor,is a protein widely expressed in various tissues.Reportedly,the dysregulation of GMEB1 is linked to the genesis and development of multiple cancers.AIM To explore GMEB1’s biological functions in hepatocellular carcinoma(HCC)and figuring out the molecular mechanism.METHODS GMEB1 expression in HCC tissues was analyzed employing the StarBase database.Immunohistochemical staining,Western blotting and quantitative realtime PCR were conducted to examine GMEB1 and Yes-associate protein 1(YAP1)expression in HCC cells and tissues.Cell counting kit-8 assay,Transwell assay and flow cytometry were utilized to examine HCC cell proliferation,migration,invasion and apoptosis,respectively.The JASPAR database was employed for predicting the binding site of GMEB1 with YAP1 promoter.Dual-luciferase reporter gene assay and chromatin immunoprecipitation-qPCR were conducted to verify the binding relationship of GMEB1 with YAP1 promoter region.RESULTS GMEB1 was up-regulated in HCC cells and tissues,and GMEB1 expression was correlated to the tumor size and TNM stage of HCC patients.GMEB1 overexpression facilitated HCC cell multiplication,migration,and invasion,and suppressed the apoptosis,whereas GMEB1 knockdown had the opposite effects.GMEB1 bound to YAP1 promoter region and positively regulated YAP1 expression in HCC cells.CONCLUSION GMEB1 facilitates HCC malignant proliferation and metastasis by promoting the transcription of the YAP1 promoter region.

AU-rich element-binding proteins in colorectal cancer

Trans-acting factors controlling mRNA fate are critical for the post-transcriptional regulation of inflammation-related genes, as well as for oncogene and tumor suppressor expression in human cancers. Among them, a group of RNA-binding proteins called "Adenylate-Uridylate-rich elements binding proteins"(AUBPs)control mRNA stability or translation through their binding to AU-rich elements enriched in the 3'UTRs of inflammation-and cancer-associated mRNA transcripts. AUBPs play a central role in the recruitment of target mRNAs into small cytoplasmic foci called Processing-bodies and stress granules(also known as P-body/SG). Alterations in the expression and activities of AUBPs and Pbody/SG assembly have been observed to occur with colorectal cancer(CRC)progression, indicating the significant role AUBP-dependent post-transcriptional regulation plays in controlling gene expression during CRC tumorigenesis.Accordingly, these alterations contribute to the pathological expression of many early-response genes involved in prostaglandin biosynthesis and inflammation,along with key oncogenic pathways. In this review, we summarize the current role of these proteins in CRC development. CRC remains a major cause of cancer mortality worldwide and, therefore, targeting these AUBPs to restore efficient post-transcriptional regulation of gene expression may represent an appealing therapeutic strategy.

Hippocampal expression of synaptic structural proteins and phosphorylated cAMP response element-binding protein in a rat model of vascular dementia induced by chronic cerebral hypoperfusion

The present study established a rat model of vascular dementia induced by chronic cerebral hypoperfusion through permanent ligation of bilateral common carotid arteries.At 60 days after modeling,escape latency and swimming path length during hidden-platform acquisition training in Morris water maze significantly increased in the model group.In addition,the number of accurate crossings over the original platform significantly decreased,hippocampal CA1 synaptophysin and growth-associated protein 43 expression significantly decreased,cAMP response element-binding protein expression remained unchanged,and phosphorylated cAMP response element-binding protein expression significantly decreased.Results suggested that abnormal expression of hippocampal synaptic structural protein and cAMP response element-binding protein phosphorylation played a role in cognitive impairment following chronic cerebral hypoperfusion.

Mechanisms of extracellular signal-regulated kinase/cAMP response element-binding protein/brain-derived neurotrophic factor signal transduction pathway in depressive disorder

The extracellular signal-regulated kinase/cAMP response element-binding protein/brain-derived neurotrophic factor signal transduction pathway plays an important role in the mechanism of action of antidepressant drugs and has dominated recent studies on the pathogenesis of depression. In the present review we summarize the known roles of extracellular signal-regulated kinase, cAMP response element-binding protein and brain-derived neurotrophic factor in the pathogenesis of depression and in the mechanism of action of antidepressant medicines. The extracellular signal-regulated kinase/cAMP response element-binding protein/brain-derived neurotrophic factor pathway has potential to be used as a biological index to help diagnose depression, and as such it is considered as an important new target in the treatment of depression.

The role of cholesterol in modifying the lipid-lowering effects of Fuzhuan brick-tea in Caenorhabditis elegans via SBP-1/SREBP

Fuzhuan brick-tea(FZT)has long been consumed for its supposed weight loss and lipid-lowering benefi ts.In this study,we show that the regulation of fat storage in Caenorhabditis elegans from a water extract of FZT was affected by cholesterol levels.We found that FZT signifi cantly decreased fat storage under normal cholesterol levels or in a cholesterol-free diet,while lipid accumulation was increased for a high cholesterol diet.Moreover,this mechanism may involve the conserved sterol regulatory element-binding protein(SREBP)/mediator-15(MDT-15)signaling pathway and the nuclear hormone receptor NHR-80.In addition,lipid synthesis-related genes inhibited by FZT were partially affected by a cholesterol-free diet.Thus,our fi ndings suggested that the potential lipid-lowering effects of FZT may depend on the cholesterol level,which may help to improve the consumption of FZT.

Effect of Tiantai No.1 (天泰1号) on β-Amyloid-induced Neurotoxicity and NF-κ B and cAMP Responsive Element-binding Protein

Objective： To investigate the effect and molecular mechanism of Tiantai No.1 （天泰1号）, a compound Chinese herbal preparation, for the prevention and reduction of neurotoxicity induced by betaamyloid peptides （Abeta） in vitro and its effects on nuclear factor-κB （NF-κB） and cAMP responsive element-binding protein （CREB） pathways using the gene transfection technique. Methods： B104 neuronal cells were used to examine the effects of Tiantai No.1 on lowering the neurotoxicity induced by Abeta. The cells were pre-treated with Tiantai No.1 at doses of 50, 100,150, or 200μg/mL respectively for 3 days and co-treated with Tiantai No.1 and beta-amyloid peptidel-40 （Aβ 1-40, 10 μmol/L） for 48 h or post-treated with Tiantai No.1 for 48 h after the cells were exposed to beta-amyloid peptides25-35 （Aβ 25-35） for 8 h. In gene transfection assays, cells were treated with Tiantai No.1 at 50 μg/mL and 150μg/mL for 5 days or co-treated with Tiantai No.1 and A 13 1-40 （5 μmo/L） for 3 days after electroporation for the evaluation of NF- κB and CREB expression. Results： Pre-treating and co-treating B104 neuronal cells with Tiantai No.1 lowered the neurotoxicity induced by Abeta, and post-treating with Tiantai No.1 reduced or blocked B104 neuronal apoptotic death induced by Abeta （P〈0.05, P〈0.01）. With a dose-dependent relationship, the same treatments increased the expression of NF-κB or CREB in B104 neuronal cells （P〈0.05, P〈0.01）. Meanwhile, Tiantai No.1 reduced Aβ-40 induced inhibition on NF-κB expression （P〈0.01）. Conclusions： Tiantai No.1 can protect neurons against the neurotoxicity induced by Abeta. The neuroprotective mechanisms may be associated with the activation of NF-κB and cAMP cellular signal pathways.

PPARα activator irbesartan suppresses the proliferation of endometrial carcinoma cells via SREBP1 and ARID1A

Endometrial carcinoma(EMC)is associated with obesity;however,the underlying mechanisms have not yet been elucidated.Peroxisome proliferator-activated receptor alpha(PPARα)is a nuclear receptor that is involved in lipid,glucose,and energy metabolism.PPARαreportedly functions as a tumor suppressor through its effects on lipid metabolism;however,the involvement of PPARαin the development of EMC remains unclear.The present study demonstrated that the immunohistochemical expression of nuclear PPARαwas lower in EMC than in normal endometrial tissues,suggesting the tumor suppressive nature of PPARα.A treatment with the PPARαactivator,irbesartan,inhibited the EMC cell lines,Ishikawa and HEC1A,by down-regulating sterol regulatory element-binding protein 1(SREBP1)and fatty acid synthase(FAS)and up-regulating the tumor suppressor genes p21 and p27,antioxidant enzymes,and AT-rich interaction domain 1A(ARID1A).These results indicate the potential of the activation of PPARαas a novel therapeutic approach against EMC.

Stress granules in colorectal cancer:Current knowledge and potential therapeutic applications

Stress granules(SGs)represent important non-membrane cytoplasmic compartments,involved in cellular adaptation to various stressful conditions(e.g.,hypoxia,nutrient deprivation,oxidative stress).These granules contain several scaffold proteins and RNA-binding proteins,which bind to mRNAs and keep them translationally silent while protecting them from harmful conditions.Although the role of SGs in cancer development is still poorly known and vary between cancer types,increasing evidence indicate that the expression and/or the activity of several key SGs components are deregulated in colorectal tumors but also in pre-neoplastic conditions(e.g.,inflammatory bowel disease),thus suggesting a potential role in the onset of colorectal cancer(CRC).It is therefore believed that SGs formation importantly contributes to various steps of colorectal tumorigenesis but also in chemoresistance.As CRC is the third most frequent cancer and one of the leading causes of cancer mortality worldwide,development of new therapeutic targets is needed to offset the development of chemoresistance and formation of metastasis.Abolishing SGs assembly may therefore represent an appealing therapeutic strategy to re-sensitize colon cancer cells to anti-cancer chemotherapies.In this review,we summarize the current knowledge on SGs in colorectal cancer and the potential therapeutic strategies that could be employed to target them.

Entacapone promotes hippocampal neurogenesis in mice

Entacapone,a catechol-O-methyltransferase inhibitor,can strengthen the therapeutic effects of levodopa on the treatment of Parkinson’s disease.However,few studies are reported on whether entacapone can affect hippocampal neurogenesis in mice.To investigate the effects of entacapone,a modulator of dopamine,on proliferating cells and immature neurons in the mouse hippocampal dentate gyrus,60 mice(7 weeks old)were randomly divided into a vehicle-treated group and the groups treated with 10,50,or 200 mg/kg entacapone.The results showed that 50 and 200 mg/kg entacapone increased the exploration time for novel object recognition.Immunohistochemical staining results revealed that after entacapone treatment,the numbers of Ki67-positive proliferating cells,doublecortin-positive immature neurons,and phosphorylated cAMP response element-binding protein(pCREB)-positive cells were significantly increased.Western blot analysis results revealed that treatment with tyrosine kinase receptor B(TrkB)receptor antagonist significantly decreased the exploration time for novel object recognition and inhibited the expression of phosphorylated TrkB and brain-derived neurotrophic factor(BDNF).Entacapone treatment antagonized the effects of TrkB receptor antagonist.These results suggest that entacapone treatment promoted hippocampal neurogenesis and improved memory function through activating the BDNF-TrkB-pCREB pathway.This study was approved by the Institutional Animal Care and Use Committee of Seoul National University(approval No.SNU-130730-1)on February 24,2014.

Recent advances in research on natural product inhibitors of SREBPs

Sterol regulatory element-binding proteins(SREBPs)are a class of cholesterol-sensitive transcription factors that play important roles in lipid metabolism.Natural product inhibitors of SREBPs have been shown to inhibit the synthesis of free fatty acids and cholesterol,promote the burning of brown fat,and relieve insulin resistance by inhibiting different links during the synthesis,cleavage,and transport of SREBPs,thereby improving obesity,diabetes,atherosclerosis,and other metabolic diseases and disorders.There are numerous Chinese herbal medicines with verified efficacy in the treatment of metabolic diseases,including Coptis chinensis Franch.and Pueraria peduncularis Grah.for diabetes,Pueraria peduncularis Grah.,Epimedium brevicornum Maxim.,and Panax ginseng C.A.Meyer for osteoporosis,and Nelumbo nucifera Gaertn.and Poria cocos(Schw.)Wolf.for obesity.Present-day research on the mechanisms underlying the activity of traditional Chinese medicine has indicated that certain chemical components of these traditional preparations can be used to treat metabolic diseases by inhibiting SREBPs.Progress in the research on natural product SREBP inhibitors is continuing apace,and the mechanisms of action of certain small molecules have become well established.In this study,we review recent progress in the research on natural small-molecule inhibitors of SREBPs,including flavonoids,saponins,triterpenoids,and alkaloids,which we hope will provide a useful reference for future research and development of drugs for the treatment of metabolic diseases.

Sodium acetate promotes fat synthesis by suppressing TATA element modulatory factor 1 in bovine mammary epithelial cells

Short-chain fatty acids are important nutrients that regulate milk fat synthesis.They regulate milk syn-thesis via the sterol regulatory element binding protein 1(SREBP1)pathway;however,the details are still unknown.Here,the regulation and mechanism of sodium acetate(SA)in milk fat synthesis in bovine mammary epithelial cells(BMECs)were assessed.BMECs were treated with SA supplementation(SAþ)or without SA supplementation(SA-),and milk fat synthesis and activation of the SREBP1 pathway were increased(P=0.0045;P=0.0042)by SAþand decreased(P=0.0068;P=0.0031)by SA-,respectively.Overexpression or inhibition of SREBP1 demonstrated that SA promoted milk fat synthesis(P=0.0045)via the SREBP1 pathway.Overexpression or inhibition of TATA element modulatory factor 1(TMF1)demon-strated that TMF1 suppressed activation of the SREBP1 pathway(P=0.0001)and milk fat synthesis(P=0.0022)activated by SAþ.Overexpression or inhibition of TMF1 and SREBP1 showed that TMF1 suppressed milk fat synthesis(P=0.0073)through the SREBP1 pathway.Coimmunoprecipitation analysis revealed that TMF1 interacted with SREBP1 in the cytoplasm and suppressed the nuclear localization of SREBP1(P=0.0066).The absence or presence of SA demonstrated that SA inhibited the expression of TMF1(P=0.0002)and the interaction between TMF1 and SREBP1(P=0.0001).Collectively,our research sug-gested that TMF1 was a new negative regulator of milk fat synthesis.In BMECs,SA promoted the SREBP1 pathway and milk fat synthesis by suppressing TMF1.This study enhances the current understanding of the regulation of milk fat synthesis and provides new scientific data for the regulation of milk fat synthesis.

Mori Cortex extract ameliorates nonalcoholic fatty liver disease( NAFLD) and insulin resistance in high-fat-diet/streptozotocininduced type 2 diabetes in rats

Nonalcoholic fatty liver disease(NAFLD) and type 2 Diabetes Mellitus(T2 DM) are highly prevalent diseases and are closely associated, with NAFLD being present in the majority of T2 DM patients. In Asian traditional medicine, Mori Cortex is widely used for the treatment of diabetes and hyperlipidemia. However, whether it has a therapeutic effect on T2 DM associated with NAFLD is still unknown. The present study showed that the oral treatment with Mori Cortex extract(MCE; 10 g·kg-1·d-1) lowered the blood lipid levels and reversed insulin resistance(IR) in high fat-diet/streptozotocin-induced type 2 diabetes in rats. The expression levels of sterol receptor element-binding protein-1 c(SREBP-1 c) and carbohydrate-responsive element binding protein(Ch REBP), which are involved in steatosis in NAFLD rats, were measured in the liver samples. MCE decreased the protein and m RNA expression levels of SREBP-1 c and Ch REBP. In conclusion, down-regulation of SREBP-1 c and Ch REBP might contribute to the protective effect of MCE on hepatic injury and IR in the rats with T2 DM associated with NAFLD.

Activation of glycine site and GluN2B subunit of NMDA receptors is necessary for ERK/CREB signaling cascade in rostral anterior cingulate cortex in rats:Implications for affective pain

Objective The rostral anterior cingulate cortex （rACC） is implicated in processing the emotional component of pain. N-methyl-D-aspartate receptors （NMDARs） are highly expressed in the rACC and mediate painrelated affect by activating a signaling pathway that involves cyclic adenosine monophosphate （cAMP）/protein ki- nase A （PKA） and/or extracellular regulated kinase （ERK）/cAMP-response element-binding protein （CREB）. The present study investigated the contributions of the NMDAR glycine site and GluN2B subunit to the activation of ERK and CREB both in vitro and in vivo in rat rACC. Methods Immunohistochemistry and Western blot analy- sis were used to separately assess the expression of phospho-ERK （pERK） and phospho-CREB （pCREB） in vitro and in vivo. Double immunostaining was also used to determine the colocalization of pERK and pCREB. Results Both bath application of NMDA in brain slices in vitro and intraplantar injection of formalin into the rat hindpaw in vivo induced significant up-regulation of pERK and pCREB in the rACC, which was inhibited by the NMDAR antago- nist DL-2-amino-5-phospho-novaleric acid. Selective blockade of the NMDAR GluN2B subunit and the glycine- binding site, or degradation of endogenous D-serine, a co-agonist for the glycine site, significantly decreased the up- regulation of pERK and pCREB expression in the rACC. Further, the activated ERK predominantly colocalized with CREB. Conclusion Either the glycine site or the GluN2B subunit of NMDARs participates in the phosphorylation of ERK and CREB induced by bath application of NMDA in brain slices or hindpaw injection of 5% formalin in rats, and these might be fundamental molecular mechanisms underlying pain affect.

Hypolipidemic effect of SIPI-7623,a derivative of an extract from oriental wormwood,through farnesoid X receptor antagonism

Farnesoid X receptor(FXR) is a member of the nuclear receptor superfamily of ligand-activated transcription factors.As a metabolic regulator,FXR plays key roles in bile acid and cholesterol metabolism and lipid and glucose homeostasis.Therefore,FXR is a potential drug target for several metabolic syndromes,especially those related to lipidemia disorders.In the present study,we identified small molecule SIPI-7623,a derivative of an extract from Oriental wormwood(Artemisia capillaris),and found that it specifically upregulated the expression of cholesterol-7-alpha-hydroxylase(CYP7 A1),downregulated the expression of sterol-regulatory element-binding protein 1 c(SREBP-1 c) in the liver,and inhibited the expression of ileal bile acid binding-protein(IBABP) in the ileum of rats.We found that inhibition of FXR by SIPI-7623 decreased the level of cholesterol and triglyceride.SIPI-7623 reduced the levels of cholesterol and triglyceride in in vitro Hep G2 cell models,ameliorated diet-induced atherosclerosis,and decreased the serum lipid content on rats and rabbits model of atherosclerosis in vivo.Furthermore,SIPI-7623 decreased the extent of atherosclerotic lesions.Our resutls demonstrated that antagonism of the FXR pathway can be employed as a therapeutic strategy to treat metabolic diseases such as hyperlipidemia and atherosclerosis.In conclusion,SIPI-7623 could be a promising lead compound for development of drugs to treat hyperlipidemia and atherosclerosis.

Nutrient mTORC1 signaling contributes to hepatic lipid metabolism in the pathogenesis of non-alcoholic fatty liver disease

Energy metabolism is maintained by the complex homeostatic system in multiple cells and organs involving“nutrient signaling”or“nutrient sensor”.Overnutrient-induced chronic metabolic diseases,as the hallmarks of the 21st century’s public health,are growing threat worldwide.In the past two decades,non-alcoholic fatty liver disease(NAFLD)has emerged as the most prevalent form of chronic liver dis-ease,affecting globally,and increases the risk of incident obesity,type 2 diabetes,and insulin resistance.NAFLD begins with the excessive triglyceride accumulation in hepatocytes,and develops to hepatocel-lular steatosis with inflammation(non-alcoholic steatohepatitis,NASH),fibrosis,cirrhosis,and ultimately hepatocellular carcinoma(HCC).The liver is the central mediator of lipid metabolism by regulation of fatty acid(FA)uptake,manufacture,store,export,and oxidation in response to physiological fluctuations of nutrient.Sterol regulatory element-binding protein c(SREBP-1c)-mediated de novo lipogenesis(DNL)is an important nutritional regulator in biosynthesis of FAs and triglyceride in the liver.Mechanistic target of rapamycin complex 1(mTORC1),as a central hub of nutrient signaling,controls cellular metabolism and growth mainly via increasing anabolic processes and inhibiting catabolic processes in response to physiological fluctuations of nutrient.mTORC1 activation contributes to regulation of DNL by increasing SREBP1 transcription,which contributes to NAFLD pathogenesis and accelerates NAFLD-related HCC development.In this review,we provide the comprehensive understanding of the molec-ular mechanism of SREBPs and autophagy to control hepatic lipid homeostasis under nutrient availability in physiological and pathophysiological states,and highlight how nutrient mTORC1 signaling coordi-nately to integrate the lipid metabolic regulation and therapeutic targets in NAFLD and HCC.