Ying Yang 1 Research Articles

TMEM17 Promotes Tumor Progression in Glioblastoma by Activating the PI3K/AKT Pathway.

Glioblastoma (GBM) is a highly aggressive and fast-growing brain tumor, characterized by rapid progression, a very poor prognosis, and a high likelihood of recurrence. Thus, effective new therapeutic targets are urgently needed. Transmembrane proteins (TMEMs) have pro-cancer effects on multiple cancer types, but the mechanisms underlying the effects of TMEM17, particularly its role in GBM, remain unclear. We conducted bioinformatics analyses and immunohistochemistry to evaluate the role of TMEM17 in a variety of cancer types. Functional assays were conducted included the Cell Counting Kit-8 assay, annexin V-FITC/PI double staining, 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, wound healing assay, transwell invasion assay, and dual luciferase assay. We found that TMEM17 is associated with a poor prognosis in GBM. Prognostic analyses confirmed that high TMEM17 expression predicted poorer survival, establishing its significance as an independent prognostic factor. Functional assays demonstrated that silencing TMEM17 in GBM cell lines inhibited proliferation and invasion, and induced apoptosis, underscoring its role in tumor aggressiveness. From a mechanistic perspective, we discovered that the Ying Yang 1 (YY1) transcription factor can bind to the promoter of TMEM17, regulating its upregulation. Regarding downstream mechanisms, knocking down TMEM17 inhibited the phosphoinositide 3-kinase/AKT pathway. These findings suggest that TMEM17 plays a significant role in GBM and may be a potential therapeutic target for this cancer. These data prove that TMEM17 plays a key role in the regulation of GBM and has great potential as a clinical therapeutic target for GBM.

CircRNA-0015004 act as a ceRNA to promote RCC2 expression in hepatocellular carcinoma

Although circular RNAs (circRNA) have been demonstrated to modulate tumor initiation and progression, their roles in the proliferation of hepatocellular carcinoma (HCC) are still poorly understood. Based on the analysis of GEO data (GSE12174), hsa-circRNA-0015004 (circ-0015004) was screened and validated in 80 sets of HCC specimens. Subcellular fractionation analysis was designed to determine the cellular location of circ-0015004. Colony formation and cell counting kit-8 were performed to investigate the role of circ-0015004 in HCC. Dual-luciferase reporter gene assays, RNA immunoprecipitation and chromatin immunoprecipitation were employed to verify the interaction among circ-0015004, miR-330-3p and regulator of chromatin condensation 2 (RCC2). The expression level of circ-0015004 was significantly upregulated in HCC cell lines and HCC tissues. HCC patients with higher circ-0015004 levels displayed shorter overall survival, and higher tumor size and TNM stage. Moreover, knockdown of circ-0015004 significantly reduced HCC cell proliferation in vitro and inhibited the growth of HCC in nude mice. Mechanistic studies revealed that circ-0015004 could upregulate the expression of RCC2 by sponging miR-330-3p, thereby promoting HCC cell proliferation. Furthermore, we identified that Ying Yang 1 (YY1) could function as an important regulator of circ-0015004 transcription. This study systematically demonstrated the novel regulatory signaling of circ-0015004/miR-330-3p/RCC2 axis in promoting HCC progression, providing insight into HCC diagnosis and treatment from bench to clinic.

YY1/miR-140-5p/Jagged1/Notch axis mediates cartilage progenitor/stem cells fate reprogramming in knee osteoarthritis.

Osteoarthritis is a multifactorial disease characterized by cartilage degeneration, while cartilage progenitor/stem cells (CPCs) are responsible for endogenous cartilage repair. However, the relevant regulatory mechanisms of CPCs fate reprogramming in OA are rarely reported. Recently, we observed fate disorders in OA CPCs and found that microRNA-140-5p (miR-140-5p) protects CPCs from fate changes in OA. This study further mechanistically investigated the upstream regulator and downstream effectors of miR-140-5p in OA CPCs fate reprogramming. As a result, luciferase reporter assay and validation assays revealed that miR-140-5p targets Jagged1 and inhibits Notch signaling in human CPCs, and the loss-/gain-of-function experiments and rescue assays discovered that miR-140-5p improves OA CPCs fate, but this effect can be counteracted by Jagged1. Moreover, increased transcription factor Ying Yang 1 (YY1) was associated with OA progression, and YY1 could disturb CPCs fate via transcriptionally repressing miR-140-5p and enhancing the Jagged1/Notch signaling. Finally, the relevant changes and mechanisms of YY1, miR-140-5p, and Jagged1/Notch signaling in OA CPCs fate reprogramming were validated in rats. Conclusively, this study identified a novel YY1/miR-140-5p/Jagged1/Notch signaling axis that mediates OA CPCs fate reprogramming, wherein YY1 and Jagged1/Notch signaling exhibits an OA-stimulative role, and miR-140-5p plays an OA-protective effect, providing attractive targets for OA therapeutics.

Breaking boundaries: Pan BETi disrupt 3D chromatin structure, BD2-selective BETi are strictly epigenetic transcriptional regulators.

Bromodomain and extraterminal proteins (BETs) are more than just epigenetic regulators of transcription. Here we highlight a new role for the BET protein BRD4 in the maintenance of higher order chromatin structure at Topologically Associating Domain Boundaries (TADBs). BD2-selective and pan (non-selective) BET inhibitors (BETi) differentially support chromatin structure, selectively affecting transcription and cell viability. Using RNA-seq and BRD4 ChIP-seq, the differential effect of BETi treatment on the transcriptome and BRD4 chromatin occupancy of human aortic endothelial cells from diabetic patients (dHAECs) stimulated with TNFα was evaluated. Chromatin decondensation and DNA fragmentation was assessed by immunofluorescence imaging and quantification. Key dHAEC findings were verified in proliferating monocyte-like THP-1 cells using real time-PCR, BRD4 co-immunoprecipitation studies, western blots, proliferation and apoptosis assays. We discovered that 1) BRD4 co-localizes with Ying-Yang 1 (YY1) at TADBs, critical chromatin structure complexes proximal to many DNA repair genes. 2) BD2-selective BETi enrich BRD4/YY1 associations, while pan-BETi do not. 3) Failure to support chromatin structures through BRD4/YY1 enrichment inhibits DNA repair gene transcription, which induces DNA damage responses, and causes widespread chromatin decondensation, DNA fragmentation, and apoptosis. 4) BD2-selective BETi maintain high order chromatin structure and cell viability, while reducing deleterious pro-inflammatory transcription. BRD4 plays a previously unrecognized role at TADBs. BETi differentially impact TADB stability. Our results provide translational insight for the development of BETi as therapeutics for a range of diseases including CVD, chronic kidney disease, cancer, and COVID-19.

BAP1 and YY1 regulate expression of death receptors in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare, aggressive, and incurable cancer arising from the mesothelial lining of the pleura, with few available treatment options. We recently reported that loss of function of the nuclear deubiquitinase BRCA1-associated protein 1 (BAP1), a frequent event in MPM, is associated with sensitivity to tumor necrosis factor–related apoptosis-inducing ligand (TRAIL)–mediated apoptosis. As a potential underlying mechanism, here we report that BAP1 negatively regulates the expression of TRAIL receptors: death receptor 4 (DR4) and death receptor 5 (DR5). Using tissue microarrays of tumor samples from MPM patients, we found a strong inverse correlation between BAP1 and TRAIL receptor expression. BAP1 knockdown increased DR4 and DR5 expression, whereas overexpression of BAP1 had the opposite effect. Reporter assays confirmed wt-BAP1, but not catalytically inactive BAP1 mutant, reduced promoter activities of DR4 and DR5, suggesting deubiquitinase activity is required for the regulation of gene expression. Co-immunoprecipitation studies demonstrated direct binding of BAP1 to the transcription factor Ying Yang 1 (YY1), and chromatin immunoprecipitation assays revealed BAP1 and YY1 to be enriched in the promoter regions of DR4 and DR5. Knockdown of YY1 also increased DR4 and DR5 expression and sensitivity to TRAIL. These results suggest that BAP1 and YY1 cooperatively repress transcription of TRAIL receptors. Our finding that BAP1 directly regulates the extrinsic apoptotic pathway will provide new insights into the role of BAP1 in the development of MPM and other cancers with frequent BAP1 mutations.

Plasma Membrane Calcium ATPase Regulates Stoichiometry of CD4+ T-Cell Compartments.

Immune responses involve mobilization of T cells within naïve and memory compartments. Tightly regulated Ca2+ levels are essential for balanced immune outcomes. How Ca2+ contributes to regulating compartment stoichiometry is unknown. Here, we show that plasma membrane Ca2+ ATPase 4 (PMCA4) is differentially expressed in human CD4+ T compartments yielding distinct store operated Ca2+ entry (SOCE) profiles. Modulation of PMCA4 yielded a more prominent increase of SOCE in memory than in naïve CD4+ T cell. Interestingly, downregulation of PMCA4 reduced the effector compartment fraction and led to accumulation of cells in the naïve compartment. In silico analysis and chromatin immunoprecipitation point towards Ying Yang 1 (YY1) as a transcription factor regulating PMCA4 expression. Analyses of PMCA and YY1 expression patterns following activation and of PMCA promoter activity following downregulation of YY1 highlight repressive role of YY1 on PMCA expression. Our findings show that PMCA4 adapts Ca2+ levels to cellular requirements during effector and quiescent phases and thereby represent a potential target to intervene with the outcome of the immune response.

The role of molecular mechanism of Ten-Eleven Translocation2 (TET2) family proteins in pathogenesis of cardiovascular diseases (CVDs).

Cardiovascular disease (CVD) is one of the most common diseases worldwide. The underlying pathogenesis of the disease has not yet been determined, but many factors have been identified. Tet methylcytosine dioxygenase 2 (TET2) is one of the epigenetic factors involved in regulating many genes. Therefore, based on the studies shown, this factor plays an important role in preventing the occurrence of CVD. TET2 has been shown to increase angiogenesis by expressing Robo4. It also increases the activity of Matrix metalloproteinases (MMPs) and stimulates the secretion of Vascular endothelial growth factor angiogenesis. On the other hand, it has been shown that TET2 regulates the expression of several genes and the development of the heart during the embryonic period due to its oxygenating role. TET2 has been shown to regulates the expression of the genes such as Ying Yang1 (YY1), Sox9b, Inhbaa and many other genes that ultimately lead to the differentiation of cardiomyocytes. On the other hand, it has been shown that some Long non coding RNA and MicroRNAs reduce TET2 expression and CVD. Finally, it is concluded that inducing TET2 expression can be a good therapeutic strategy to prevent or improve CVD.

Adenosine Receptor A1-A2a Heteromers Regulate EAAT2 Expression and Glutamate Uptake via YY1-Induced Repression of PPARγ Transcription.

Adenosine receptors A1 (A1AR) and A2a (A2aAR) play an important role in regulating glutamate uptake to avoid glutamate accumulation that causes excitotoxicity in the brain; however, the precise mechanism of the effects of A1AR and A2aAR is unclear. Herein, we report that expression of the A1AR protein in the astrocyte membrane and the level of intracellular glutamate were decreased, while expression of the A2aR protein was elevated in cells exposed to oxygen-glucose deprivation (OGD) conditions. Coimmunoprecipitation (Co-IP) experiments showed that A1AR interacts with A2aAR under OGD conditions. The activation of A1AR and inactivation of A2aAR by 2-chloro-N6-cyclopentyladenosine (CCPA) and SCH58251, respectively, partly reversed OGD-mediated glutamate uptake dysfunction, elevated EAAT2, and PPARγ protein levels, and suppressed the expression of Ying Yang 1 (YY1). Both the silencing of YY1 and the activation of PPARγ upregulated EAAT2 expression. Moreover, YY1 silencing elevated the PPARγ level under both normal and OGD conditions. Histone deacetylase (HDAC)1 was found to interact with YY1, and HDAC1 silencing improved PPARγ promoter activity. Taken together, our findings suggest that A1AR-A2aAR heteromers regulate EAAT2 expression and glutamate uptake through the YY1-mediated recruitment of HDAC1 to the PPARγ promoter region.

Inhibition of PHLDA2 transcription by DNA methylation and YY1 in goat placenta.

Pleckstrin homology-like domain family A member 2 (PHLDA2) is essential for placental development in mammals. This study was conducted to investigate transcriptional regulation of goat PHLDA2 in the placenta. Real-time PCR and Western blot analyses showed different expression of the PHLDA2 in goat placentas during gestation with highest expression at 30 and 45days post coitus (P<0.05). Luciferase reporter assays demonstrated the highest promoter activity in the region of -1023/+20 (P<0.05). A CpG island was defined within -631/+379 region, where lower level of CpG-methylation was detected with bisulfite sequencing PCR in the placenta than that in the spleen and liver (P<0.05). Meanwhile, in vitro experiments showed that 5-AzaC enhanced the gene expression in a dose-dependent manner. Site-directed mutation in vitro demonstrated that transcription factor Ying-yang 1 (YY1) had an inhibitory effect on the PHLDA2 expression, and the inhibition was further confirmed with overexpression and siRNA constructs of YY1. ChIP and RE-ChIP analyses further identified the binding of YY1 to the PHLDA2 promoter by interaction with histone deacetylase 1 (HDAC1) and HDAC3. This study uncovers the negative regulation of the CpG-methylation and YY1 on goat PHLDA2 expression. YY1 prefers binding to CpG-methylation sequences, and inhibits goat PHLDA2 expression via recruiting HDAC1 and 3.

MicroRNA-140 impedes DNA repair by targeting FEN1 and enhances chemotherapeutic response in breast cancer.

An increased DNA repair capacity is associated with drug resistance and limits the efficacy of chemotherapy in breast cancers. Flap endonuclease 1 (FEN1) participates in various DNA repair pathways and contributes to cancer progression and drug resistance in chemotherapy. Inhibition of FEN1 serves as a potent strategy for cancer therapy. Here, we demonstrate that microRNA-140 (miR-140) inhibits FEN1 expression via directly binding to its 3' untranslated region, leading to impaired DNA repair and repressed breast cancer progression. Overexpression of miR-140 sensitizes breast cancer cells to chemotherapeutic agents and overcomes drug resistance in breast cancer. Notably, ectopic expression of FEN1 abates the effects of miR-140 on DNA damage and the chemotherapy response in breast cancer cells. Furthermore, the transcription factor/repressor Ying Yang 1 (YY1) directly binds to the miR-140 promoter and activates miR-140 expression, which is attenuated in doxorubicin resistance. Our results demonstrate that miR-140 acts as a tumor suppressor in breast cancer by inhibiting FEN1 to repress DNA damage repair and reveal miR-140 to be a new anti-tumorigenesis factor for adjunctive breast cancer therapy. This novel mechanism will enhance the treatment effect of chemotherapy in breast cancer.

FAM3C-YY1 axis is essential for TGFβ-promoted proliferation and migration of human breast cancer MDA-MB-231 cells via the activation of HSF1.

Family with sequence similarity three member C (FAM3C) (interleukin‐like EMT inducer [ILEI]), heat shock factor 1 (HSF1) and Ying‐Yang 1 (YY1) have been independently reported to be involved in the pathogenesis of various cancers. However, whether they are coordinated to trigger the development of cancer remains unknown. This study determined the role and mechanism of YY1 and HSF1 in FAM3C‐induced proliferation and migration of breast cancer cells. In human MDA‐MB‐231 breast cancer cell line, transforming growth factor‐β (TGFβ) up‐regulated FAM3C, HSF1 and YY1 expressions. FAM3C overexpression promoted the proliferation and migration of MDA‐MB‐231 cells with YY1 and HSF1 up‐regulation, whereas FAM3C silencing exerted the opposite effects. FAM3C inhibition repressed TGFβ‐induced HSF1 activation, and proliferation and migration of breast cancer cells. YY1 was shown to directly activate HSF1 transcription to promote the proliferation and migration of breast cancer cells. YY1 silencing blunted FAM3C‐ and TGFβ‐triggered activation of HSF1‐Akt‐Cyclin D1 pathway, and proliferation and migration of breast cancer cells. Inhibition of HSF1 blocked TGFβ‐, FAM3C‐ and YY1‐induced proliferation and migration of breast cancer cells. YY1 and HSF1 had little effect on FAM3C expression. Similarly, inhibition of HSF1 also blunted FAM3C‐ and TGFβ‐promoted proliferation and migration of human breast cancer BT‐549 cells. In human breast cancer tissues, FAM3C, YY1 and HSF1 protein expressions were increased. In conclusion, FAM3C activated YY1‐HSF1 signalling axis to promote the proliferation and migration of breast cancer cells. Furthermore, novel FAM3C‐YY1‐HSF1 pathway plays an important role in TGFβ‐triggered proliferation and migration of human breast cancer MDA‐MB‐231 cells.

Transcription Factor Yin Yang 1 Involves in Insulin Resistance-Polycystic Ovarian Syndrome by Regulating Sex Hormone Synthesis and Wnt/β-Catenin Signaling Pathway

Polycystic ovary syndrome (PCOS) is a common metabolic disorder affecting up to 15% of reproductive-aged women. Insulin resistance (IR) is considered to be the main cause of PCOS since it disrupts both the endocrine system to affect normal ovulate and induces hyperandrogenism. Therefore, to understand the underlying mechanisms on specific pathogenesis of IR is critical for IR-PCOS treatment. Here we discovered that transcriptional factor Yingyang 1 (YY1) was elevated in IR-PCOS patients comparing to non-IR-PCOS patients, and YY1 expression level highly correlated to multiple clinical characteristics of IR-PCOS patients. We confirmed this finding in an IR-PCOS rat model, in which high YY1 expression and abnormal expressions of several other key molecules were related to IR and sex hormone synthesis. To further explore the transcriptome changes and more detailed mechanisms on how YY1 contributed to IR-PCOS, a high-throughput RNA-sequencing was performed and analyzed. Knock-down of YY1 in COV434 cells affected multiple signaling pathways including endocrine, metabolic, progesterone and oocyte maturation. Among these, 18 genes tightly related to IR were identified. Collectively, our data clearly showed transcriptional factor YY1 is critical for developing IR-PCOS by regulating multiple metabolic and endocrine pathways. Funding: These studies were supported by the National Natural Science Foundation of China (Grant No. 81560245). Declaration of Interest: The authors have no conflicts of interest to declare. Ethical Approval: All procedures were approved by Ethics Committee of the first affiliated hospital of Guangxi medical University and The Third Affiliated Hospital of Sun Yat-sen University. The clinical data are acquired from medical record system and informed consents were approved and signed by each recruited patient.

C/EBPβ and YY1 bind and interact with Smad3 to modulate lipopolysaccharide-induced amelotin gene transcription in mouse gingival epithelial cells.

Junctional epithelium (JE) develops from reduced enamel epithelium during tooth formation and is critical for the maintenance of healthy periodontal tissue through ensuring appropriate immune responses and the rapid turnover of gingival epithelial cells. We have previously shown a relationship between inflammatory cytokines and expression of JE‐specific genes, such as amelotin (AMTN), in gingival epithelial cells. Here, we elucidated the effects of Porphyromonas gingivalis‐derived lipopolysaccharide (Pg LPS) on Amtn gene transcription and the interaction of transcription factors. To determine the molecular basis of transcriptional regulation of the Amtn gene by Pg LPS, we performed real‐time PCR and carried out luciferase assays using a mouse Amtn gene promoter linked to a luciferase reporter gene in mouse gingival epithelial GE1 cells. Gel mobility shift and chromatin immunoprecipitation assays were performed to identify response elements bound to LPS‐induced transcription factors. Next, we analyzed protein levels of the LPS‐induced transcription factors and the interaction of transcription factors by western blotting and immunoprecipitation. LPS increased Amtn mRNA levels and elevated luciferase activities of constructs containing regions between −116 and −238 of the mouse Amtn gene promoter. CCAAT/enhancer‐binding protein (C/EBP) 1–, C/EBP2– and Ying Yang 1 (YY1)–nuclear protein complexes were increased by LPS treatment. Furthermore, we identified LPS‐modulated interactions with C/EBPβ, YY1 and Smad3. These results demonstrate that Pg LPS regulates Amtn gene transcription via binding of C/EBPβ–Smad3 and YY1–Smad3 complexes to C/EBP1, C/EBP2 and YY1 response elements in the mouse Amtn gene promoter.

Transcriptional regulation of human amelotin gene by interleukin-1β.

One of the major causes of tooth loss is chronic inflammation of the periodontium, the tissues surrounding the tooth. Amelotin (AMTN) is a tooth enamel protein which is expressed in maturation‐stage ameloblasts and also in the internal basal lamina of junctional epithelium, a unique epithelial structure attached to the tooth surface which protects against the constant microbiological challenge to the periodontium. Localization of AMTN suggests that its function could be involved in the dentogingival attachment. The purpose of this study was to investigate the effect of interleukin‐1β (IL‐1β) on AMTN gene transcription in human gingival epithelial Ca9‐22 cells. IL‐1β increased AMTN mRNA and protein levels at 3 h, and the levels reached maximum at 6 and 12 h. IL‐1β induced luciferase activities of human AMTN gene promoter constructs (−211, −353, −501, −769, and −950AMTN), but these activities were partially inhibited in −353AMTN constructs that included 3‐bp mutations in CCAAT/enhancer binding protein 1 (C/EBP1), C/EBP2, and Ying Yang 1 (YY1) elements. Transcriptional activities induced by IL‐1β were abrogated by protein kinase A (PKA), tyrosine kinase, mitogen‐activated protein kinase kinase (MEK1/2), and phosphatidylinositol 3‐kinase (PI3K) inhibitors. Gel shift and ChIP assays showed that IL‐1β increased C/EBPβ binding to C/EBP1 and C/EBP2, and YY1 binding to YY1 elements after 3 h, and that these DNA–protein interactions were inhibited by PKA, tyrosine kinase, MEK1/2, and PI3K inhibitors. These results demonstrated that IL‐1β increases AMTN gene transcription in human gingival epithelial cells mediated through C/EBP1, C/EBP2, and YY1 elements in the human AMTN gene promoter.

Tumor necrosis factor-α stimulates human amelotin gene transcription in gingival epithelial cells.

Amelotin (AMTN) is an enamel protein that is localized in the basal lamina of ameloblasts in their maturation stage and the internal basal lamina of junctional epithelium (JE) and it is suggested that AMTN could be involved in the dentogingival attachment. To elucidate the transcriptional regulation of human AMTN gene in inflamed gingiva, we have analyzed the effect of tumor necrosis factor-α (TNF-α) on the expression of AMTN gene in Ca9-22 and Sa3 human gingival epithelial cells. Total RNAs were extracted from Ca9-22 and Sa3 cells after stimulation by TNF-α (10ng/ml). AMTN mRNA and protein levels were measured by real-time PCR and Western blotting. Transient transfection analyses were completed using the various lengths of human AMTN gene promoter constructs with or without TNF-α. Gel mobility shift and chromatin immunoprecipitation assays were performed to investigate the transcription factors bindings to the human AMTN gene promoter by TNF-α. TNF-α (10ng/ml) increased AMTN mRNA and protein levels after 12h. TNF-α induced luciferase activities of human AMTN gene promoter constructs (- 211AMTN, - 353AMTN, and - 501AMTN). TNF-α-induced luciferase activities were partially inhibited in the mutation - 353AMTN constructs that included 3-bp mutations in CCAAT enhancer-binding protein 1 (C/EBP1), C/EBP2 and Ying Yang 1 (YY1) elements. Transcriptional activities induced by TNF-α were inhibited by protein kinase A, Src-tyrosine kinase, MEK1/2, p38 kinase, NF-κB, and PI3-kinase inhibitors. Gel shift assays showed that TNF-α increased nuclear proteins binding to two types of C/EBP elements (C/EBP1 and C/EBP2) and YY1 element. The results of the chromatin immunoprecipitation assays showed that C/EBPβ binding to C/EBP1 and C/EBP2, and YY1 binding to YY1 were increased by TNF-α. These findings demonstrated that TNF-α stimulates AMTN gene transcription in human gingival epithelial cells via C/EBP1, C/EBP2, and YY1 elements in the human AMTN gene promoter.

Arundic Acid Increases Expression and Function of Astrocytic Glutamate Transporter EAAT1 Via the ERK, Akt, and NF-κB Pathways.

Glutamate is the major excitatory neurotransmitter in the brain, but excessive synaptic glutamate must be removed to prevent excitotoxic injury and death. Two astrocytic glutamate transporters, excitatory amino acid transporter (EAAT) 1 and 2, play a major role in eliminating excess glutamate from the synapse. Dysregulation of EAAT1 contributes to the pathogenesis of multiple neurological disorders, such as Alzheimer's disease (AD), ataxia, traumatic brain injuries, and glaucoma. In the present study, we investigated the effect of arundic acid on EAAT1 to determine its efficacy in enhancing the expression and function of EAAT1, and its possible mechanisms of action. The studies were carried out in human astrocyte H4 cells as well as in human primary astrocytes. Our findings show that arundic acid upregulated EAAT1 expression at the transcriptional level by activating nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Arundic acid increased astrocytic EAAT1 promoter activity, messenger RNA (mRNA)/protein levels, and glutamate uptake, while pharmacological inhibition of NF-κB or mutation on NF-κB binding sites in the EAAT1 promoter region abrogated these effects. Arundic acid increased NF-κB reporter activity and induced NF-κB nuclear translocation as well as its bindings to the EAAT1 promoter. Furthermore, arundic acid activated the Akt and ERK signaling pathways to enhance EAAT1 mRNA/protein levels. Finally, arundic acid attenuated manganese-induced decrease in EAAT1 expression by inhibiting expression of the transcription factor Ying Yang 1 (YY1). These results demonstrate that arundic acid increases the expression and function of EAAT1 via the Akt, ERK, and NF-κB signaling pathways, and reverses Mn-induced EAAT1 repression by inhibiting the Mn-induced YY1 activation.

Adult-onset hyperinsulinaemic hypoglycaemia in clinical practice: diagnosis, aetiology and management

ObjectiveIn adults with hyperinsulinaemic hypoglycaemia (HH), in particular those with insulinoma, the optimal diagnostic and management strategies remain uncertain. Here, we sought to characterise the biochemical and radiological assessment, and clinical management of adults with HH at a tertiary centre over a thirteen-year period.DesignClinical, biochemical, radiological and histological data were reviewed from all confirmed cases of adult-onset hyperinsulinaemic hypoglycaemia at our centre between 2003 and 2016. In a subset of patients with stage I insulinoma, whole-exome sequencing of tumour DNA was performed.ResultsTwenty-nine patients were identified (27 insulinoma, including 6 subjects with metastatic disease; 1 pro-insulin/GLP-1 co-secreting tumour; 1 activating glucokinase mutation). In all cases, hypoglycaemia (glucose ≤2.2 mmol/L) was achieved within 48 h of a supervised fast. At fast termination, subjects with stage IV insulinoma had significantly higher insulin, C-peptide and pro-insulin compared to those with insulinoma staged I–IIIB. Preoperative localisation of insulinoma was most successfully achieved with EUS. In two patients with inoperable, metastatic insulinoma, peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE rapidly restored euglycaemia and lowered fasting insulin. Finally, in a subset of stage I insulinoma, whole-exome sequencing of tumour DNA identified the pathogenic Ying Yang-1 (YY1) somatic mutation (c.C1115G/p.T372R) in one tumour, with all tumours exhibiting a low somatic mutation burden.ConclusionOur study highlights, in particular, the utility of the 48-h fast in the diagnosis of insulinoma, EUS for tumour localisation and the value of PRRT therapy in the treatment of metastatic disease.

The potential role of neuroinflammation and transcription factors in Parkinson disease

Parkinson disease (PD) is a neurodegenerative disorder characterized by dopaminergic neurons affected by inflammatory processes. Post-mortem analyses of brain and cerebrospinal fluid from PD patients show the accumulation of proinflammatory cytokines, confirming an ongoing neuroinflammation in the affected brain regions. These inflammatory mediators may activate transcription factors-notably nuclear factor κB, Ying-Yang 1 (YY1), fibroblast growth factor 20 (FGF20), and mammalian target of rapamycin (mTOR)-which then regulate downstream signaling pathways that in turn promote death of dopaminergic neurons through death domain-containing receptors. Dopaminergic neurons are vulnerable to oxidative stress and inflammatory attack. An increased level of inducible nitric oxide synthase observed in the substantia nigra and striatum of PD patients suggests that both cytokine-and chemokine-induced toxicity and inflammation lead to oxidative stress that contributes to degeneration of dopaminergic neurons and to disease progression. Lipopolysaccharide activation of microglia in the proximity of dopaminergic neurons in the substantia nigra causes their degeneration, and this appears to be a selective vulnerability of dopaminergic neurons to inflammation. In this review, we will look at the role of various transcription factors and signaling pathways in the development of PD.

The microRNA-635 suppresses tumorigenesis in non-small cell lung cancer.

The microRNAs represent a class of noncoding RNAs with short length and play diverse roles in many biological processes. Despite tremendous effects have been devoted, the role of miR-635 in non-small cell lung cancer (NSCLC) remains elusive. Here we report a potential tumor suppressive function of miR-635 in NSCLC. By microRNA screening based on invasion assays, we identified series of functional miRNAs. The miR-635 was then identified as a potent inhibitor of cell invasion and differentially expressed in normal and cancerous tissues. We further confirmed that Ying Yang 1 (YY1) may be the direct target of miR-635 as miR-635 transfection can significantly decrease endogenous YY1 expression which can mimic the effect of siRNA-mediated YY1 knockdown. Meanwhile, both miR-635 transfection and YY1 silencing can attenuate NSCLC cell invasion. In addition, miR-635 transfection can also significantly inhibit the growth of xenograft tumors. Taken together, our results have suggested a novel tumor suppressive role for miR-635 in NSCLC.

YY1 plays an essential role at all stages of B-cell differentiation

Ying Yang 1 (YY1) is a ubiquitously expressed transcription factor shown to be essential for pro-B-cell development. However, the role of YY1 in other B-cell populations has never been investigated. Recent bioinformatics analysis data have implicated YY1 in the germinal center (GC) B-cell transcriptional program. In accord with this prediction, we demonstrated that deletion of YY1 by Cγ1-Cre completely prevented differentiation of GC B cells and plasma cells. To determine if YY1 was also required for the differentiation of other B-cell populations, we deleted YY1 with CD19-Cre and found that all peripheral B-cell subsets, including B1 B cells, require YY1 for their differentiation. Transitional 1 (T1) B cells were the most dependent upon YY1, being sensitive to even a half-dosage of YY1 and also to short-term YY1 deletion by tamoxifen-induced Cre. We show that YY1 exerts its effects, in part, by promoting B-cell survival and proliferation. ChIP-sequencing shows that YY1 predominantly binds to promoters, and pathway analysis of the genes that bind YY1 show enrichment in ribosomal functions, mitochondrial functions such as bioenergetics, and functions related to transcription such as mRNA splicing. By RNA-sequencing analysis of differentially expressed genes, we demonstrated that YY1 normally activates genes involved in mitochondrial bioenergetics, whereas it normally down-regulates genes involved in transcription, mRNA splicing, NF-κB signaling pathways, the AP-1 transcription factor network, chromatin remodeling, cytokine signaling pathways, cell adhesion, and cell proliferation. Our results show the crucial role that YY1 plays in regulating broad general processes throughout all stages of B-cell differentiation.