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1.
Cell Rep ; 30(4): 1235-1245.e4, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31995761

RESUMO

DNA-protein crosslinks (DPCs) are a frequent form of DNA lesion and are strongly inhibitive in diverse DNA transactions. Despite recent developments, the biochemical detection of DPCs remains a limiting factor for the in-depth mechanistic understanding of DPC repair. Here, we develop a sensitive and versatile assay, designated ARK, for the quantitative analysis of DPCs in cells. ARK uses sequential chaotropic and detergent-based isolation of DPCs and substantially enhances sample purity, resulting in a 5-fold increase in detection sensitivity and a 10-fold reduction in background reading. We validate the ARK assay with genetic mutants with established deficiencies in DPC repair and demonstrate its robustness by using common DPC-inducing reagents, including formaldehyde, camptothecin, and etoposide. In addition, we show that the Fanconi anemia pathway contributes to the repair of DPCs. Thus, ARK is expected to facilitate various studies aimed at understanding both fundamental biology and translational applications of DNA-protein crosslink repair.

2.
Aging (Albany NY) ; 12(2): 1186-1200, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31958320

RESUMO

Exposure to particulate matter (PM) is associated with increased incidence of respiratory diseases. The present study aimed to investigate the roles of fibroblast growth factor 10 (FGF10) in PM-induced lung injury. Mice were intratracheally instilled with FGF10 or phosphate-buffered saline at one hour before instillation of PM for two consecutive days. In addition, the anti-inflammatory impact of FGF10 in vitro and its effect on the high-mobility group box 1 (HMGB1)-toll-like receptor 4 (TLR4) pathway was investigated. It was found that PM exposure is associated with increased inflammatory cell infiltration into the lung and increased vascular protein leakage, while FGF10 pretreatment attenuated both of these effects. FGF10 also decreased the PM-induced expression of interleukin (IL)-6, IL-8, tumor necrosis factor-α and HMGB1 in murine bronchoalveolar lavage fluid and in the supernatants of human bronchial epithelial cells exposed to PM. FGF10 exerted anti-inflammatory and cytoprotective effects by inhibiting the HMGB1-TLR4 pathway. These results indicate that FGF10 may have therapeutic values for PM-induced lung injury.

3.
DNA Repair (Amst) ; 87: 102803, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31991288

RESUMO

DNA damage response (DDR) is critically important for cell survival, genome maintenance, and its defect has been exploited therapeutically in cancer treatment. Many DDR-targeting agents have been generated and have entered the clinic and/or clinical trials. In order to provide a global and unbiased view of DDR network, we designed a focused CRISPR library targeting 365 DDR genes and performed CRISPR screens on the responses to several DDR inhibitors and DNA-damaging agents in 293A cells. With these screens, we determined responsive pathways enriched under treatment with different types of small-molecule agents. Additionally, we showed that POLE3/4-deficient cells displayed enhanced sensitivity to an ATR inhibitor, a PARP inhibitor, and camptothecin. Moreover, by performing DDR screens in isogenic TP53 wild-type and TP53 knock-out cell lines, our results suggest that the performance of our CRISPR DDR dropout screens is independent of TP53 status. Collectively, our findings indicate that CRISPR DDR screens can be used to identify potential targets of small-molecule drugs and reveal that TP53 status does not affect the outcome of these screens.

4.
Life Sci ; 243: 117323, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31954160

RESUMO

AIMS: Circular RNAs (circRNAs) have been emerged as novel regulators in multiple tumorigenesis, including melanoma. CircRNA_0084043 was recently demonstrated to be deregulated in human melanoma cells. Nevertheless, its role and mechanism are largely unrevealed in melanoma. MATERIALS AND METHODS: Expression of circ_0084043, miRNA (miR)-429 and tribbles homolog 2 (TRIB2) was detected using reverse transcription-quantitative PCR quantitative PCR (RT-qPCR) and western blotting. Cell proliferation, apoptosis, migration and invasion were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry and transwell assays, respectively. The activation of Wnt/ß-catenin pathway was evaluated by western blotting. The target binding among circ_0084043, miR-429 and TRIB2 was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation. In vivo, mice xenograft model was generated to investigate tumor growth. KEY FINDINGS: Expression of circ_0084043 and TRIB2 was upregulated in human melanoma tissues and cell lines. Both circ_0084043 knockdown and TRIB2 silencing could decrease cell proliferation, migration and invasion, but facilitate apoptosis in A375 and SK-MEL-28 cells. Furthermore, TRIB2 restoration partially abrogated the tumor-suppressive role of circ_0084043 knockdown in melanoma cells in vitro. Then, we verified that circ_0084043 positively and physically controlled TRIB2 expression through sponging miR-429. Besides, expression of ß-catenin, c-Myc and cyclinD1 was inhibited in A375 and SK-MEL-28 cells when circ_0084043 was knocked down, accompanied with increased miR-429 and decreased TRIB2. Notably, circ_0084043 downregulation impeded tumor growth of A375 cells in vivo. SIGNIFICANCE: Knockdown of circ_0084043 suppressed the malignant development of melanoma presumably through modulating miR429/TRIB2 axis and inactivating Wnt/ß-catenin signaling pathway.

5.
Mol Cell Proteomics ; 2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31900314

RESUMO

Adenosine monophosphate-activated protein kinase (AMPK) is an obligate heterotrimer that consists of a catalytic subunit (α) and two regulatory subunits (ß and γ). AMPK is a key enzyme in the regulation of cellular energy homeostasis. It has been well studied and is known to function in many cellular pathways. However, the interactome of AMPK has not yet been systematically established, although protein-protein interaction is critically important for protein function and regulation. Here, we used tandem-affinity purification, coupled with mass spectrometry (TAP-MS) analysis, to determine the interactome of AMPK and its functions. We conducted a TAP-MS analysis of all seven AMPK subunits. We identified 138 candidate high-confidence interacting proteins(HCIPs) of AMPK, which allowed us to build an interaction network of AMPK complexes. Five candidate AMPK-binding proteins were experimentally validated, underlining the reliability of our dataset. Furthermore, we demonstrated that AMPK acts with a strong AMPK-binding protein, Artemis, in non-homologous end joining. Collectively, our study established the first AMPK interactome and uncovered a new function of AMPK in DNA repair.

6.
Acupunct Med ; : acupmed2016011263, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31996011

RESUMO

OBJECTIVE: The aim of this study was to investigate the effect of electroacupuncture (EA) on recovery from acute sciatic nerve crush injury and the expression of pS6 in rats. METHODS: A total of 108 adult male Sprague-Dawley rats were randomly divided into control, model, EA and EA+rapamycin (EA+Rapa) groups. 28 rats were allocated to undergo measurement of sciatic functional index (SFI); one rat in the EA+Rapa group was unsuccessfully modelled and excluded because of an anaesthetic problem. The remaining 80 rats were allocated to undergo Western blot detection of S6 ribosomal protein (pS6, ser240/244). The model was created by mechanical clamping of the sciatic nerve stem. EA stimulation at GB30 and ST36 for 15 min separately was applied once daily for rats in the EA and EA+Rapa groups. For rats in the EA+Rapa group, rapamycin, a mammalian target of rapamycin (mTor) pathway inhibitor, was injected intramuscularly (1 mg/kg/day) near the site of crush injury in the sciatic nerve and an equivalent amount of dimethyl sulfoxide was injected in the other three groups every other day. After treatment for 7, 14, 28 and 42 days post-operation, the SFI of 27 rats was obtained to evaluate recovery of motor function and five rats from each group per stage were used for Western blot detection of pS6. RESULTS: The SFI values showed that EA could significantly promote recovery of the injured sciatic nerve but rapamycin hindered the therapeutic effect of EA. Moreover, immunoblotting indicated that EA improved the expression of pS6 in the area of the sciatic nerve crush injury and local injection of rapamycin near the injured sciatic nerve decreased its expression. The pS6 level correlated with the extent of recovery of the injury. CONCLUSIONS: This study indicated that EA may activate the mTOR signalling pathway to enhance expression of pS6 and facilitate recovery following sciatic nerve crush injury.

7.
EMBO J ; 39(1): e102406, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31782549

RESUMO

The Hippo pathway, which plays a critical role in organ size control and cancer, features numerous WW domain-based protein-protein interactions. However, ~100 WW domains and 2,000 PY motif-containing peptide ligands are found in the human proteome, raising a "WW-PY" binding specificity issue in the Hippo pathway. In this study, we have established the WW domain binding specificity for Hippo pathway components and uncovered a unique amino acid sequence required for it. By using this criterion, we have identified a WW domain-containing protein, STXBP4, as a negative regulator of YAP. Mechanistically, STXBP4 assembles a protein complex comprising α-catenin and a group of Hippo PY motif-containing components/regulators to inhibit YAP, a process that is regulated by actin cytoskeleton tension. Interestingly, STXBP4 is a potential tumor suppressor for human kidney cancer, whose downregulation is correlated with YAP activation in clear cell renal cell carcinoma. Taken together, our study not only elucidates the WW domain binding specificity for the Hippo pathway, but also reveals STXBP4 as a player in actin cytoskeleton tension-mediated Hippo pathway regulation.

8.
Bioresour Technol ; 297: 122417, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31759856

RESUMO

This study evaluates the effect of replacement of N2 with CO2 as atmosphere in catalytic pyrolysis of waste lignocellulosics with acidic and metal-modified zeolites, respectively, on the 16 EPA priority pollutant polycyclic aromatic hydrocarbons (PAHs) in bio-oils. By coupling solid phase extraction pretreatment with single ion monitoring detection, it is found that the replacement alleviates PAHs in bio-oil concerning synchronously abating the 16 PAHs with low, medium and high molecular weights, and the benzo[a]pyrene equivalent toxicity of bio-oil decreases. Meanwhile, CO2 decreases the content of small oxygenates, e.g. furans, ketones, acids, and increases phenolics and aromatics affording more stable and valuable bio-oils. Moreover, CO2 enhances carbon conversion efficiency, especially in combination with Fe-modified zeolite, which presents a synergistic effect. This study indicates the practical application of CO2 as an atmosphere in catalytic pyrolysis to improve the bio-oil quality by suppressing PAHs formation and adjusting compound constituent.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , Atmosfera , Dióxido de Carbono , Nitrogênio , Pirólise
9.
Phytochemistry ; 170: 112216, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31841782

RESUMO

Hyperelodiones A-C, three undescribed monoterpenoid polyprenylated acylphloroglucinols possessing 6/6/6 fused tricyclic core, were isolated from Hypericum elodeoides Choisy. Their gross structures were elucidated by HRESIMS and NMR data. The absolute configurations of hyperelodiones A-C were assigned by their calculated and compared electronic circular dichroism (ECD) spectra combined with their common biosynthetic origin. A fluorescence quenching assay suggested that hyperelodiones A-C could bind to RXRα-LBD, whereas hyperelodione C showed the strongest interaction with a KD of 12.81 µΜ. In addition, hyperelodiones A-C dose-dependently inhibited RXRα transactivation and the growth of HeLa and MCF-7 cells. Among them, hyperelodione C showed the most potent inhibitory activities and dose-dependent PARP cleavage. Molecular docking results suggested that hyperelodione C showed a different interaction mode compared with hyperelodione A and hyperelodione B. Thus, hyperelodione C can be considered as a promising lead compound for cancer therapy, which can bind to RXRα-LBD and induce HeLa and MCF-7 cell apoptosis.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Hypericum/química , Monoterpenos/farmacologia , Compostos Fitoquímicos/farmacologia , Receptor X Retinoide alfa/antagonistas & inibidores , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Células HeLa , Humanos , Células MCF-7 , Conformação Molecular , Simulação de Acoplamento Molecular , Monoterpenos/química , Monoterpenos/isolamento & purificação , Compostos Fitoquímicos/química , Compostos Fitoquímicos/isolamento & purificação , Receptor X Retinoide alfa/metabolismo , Relação Estrutura-Atividade , Células Tumorais Cultivadas
10.
Methods Mol Biol ; 2082: 87-104, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31849010

RESUMO

An immense amount of observable diversity exists for all traits and across global populations. In the post-genomic era, equipped with efficient sequencing capabilities and better genotyping methods, we are now able to more fully appreciate how regulation of gene expression is consequential to one's genotypes in coding and non-coding DNA. The identification of genetic loci that contribute to quantifiable variation in genetic expression is critical in further improving our understanding of the biological regulation of complex traits. Expression quantitative traits loci (eQTLs) mapping studies have provided a powerful suite of techniques for genome wide analysis to detect these regulatory effects. However, a typical eQTL analysis relies on a large number of samples with many genetic variants to achieve robust power and significance for detection. With this in mind, eQTL analysis brings about distinct computational and statistical challenges that require advanced methodological development to overcome. In recent years, many statistical and machine learning methods for eQTL analysis have been developed with the ability to provide a more complex perspective towards the identification of relationships between genetic variation and genetic expression. In this chapter, we provide a comprehensive review of statistical and machine learning methods. We will present various machine learning methods based upon regularization terms and several other statistical analysis methods. Finally, we will discuss prior knowledge integration and hyperparameter optimization.

11.
RNA Biol ; : 1-14, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31885317

RESUMO

Emerging evidence has suggested that long noncoding RNAs (lncRNAs) play an essential role in the tumorigenesis of multiple types of cancer including gastric cancer (GC). However, the potential biological roles and regulatory mechanisms of lncRNA in response to cisplatin, which may be involved in cisplatin resistance, have not been fully elucidated. In this study, we identified a novel lncRNA, cisplatin resistance-associated lncRNA (CRAL), that was downregulated in cisplatin-resistant GC cells, impaired cisplatin-induced DNA damage and cell apoptosis and thus contributed to cisplatin resistance in GC cells. Furthermore, the results indicated that CRAL mainly resided in the cytoplasm and could sponge endogenous miR-505 to upregulate cylindromatosis (CYLD) expression, which further suppressed AKT activation and led to an increase in the sensitivity of gastric cancer cells to cisplatin in vitro and in preclinical models. Moreover, a specific small molecule inhibitor of AKT activation, MK2206, effectively reversed the cisplatin resistance in GC caused by CRAL deficiency. In conclusion, we provide the first evidence that a novel lncRNA, CRAL, could function as a competing endogenous RNA (ceRNA) to reverse GC cisplatin resistance via the miR-505/CYLD/AKT axis, which suggests that CRAL could be considered a potential predictive biomarker and therapeutic target for cisplatin resistance in gastric cancer.

12.
J Cell Physiol ; 235(3): 2687-2697, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31541465

RESUMO

This study was conducted to evaluate the influence of DNA methylation of metastasis suppressor 1 (MTSS1) on prostate cancer (PCa) progression. Forty-nine paired PCa tissue samples and normal tissue samples from The Cancer Genome Atlas were analyzed. Methylome analysis, CpG island arrays and Hierarchical clustering were used to analyze methylation profiles of PCa tissues. MTSS1 methylation level was detected by methylation-specific PCR. Relative messenger RNA and the expression level of MTSS1 protein were identified by quantitative real-time PCR (qRT-PCR) and western blot analysis. The migration, invasion, proliferation, and cell cycle were detected separately by wound-healing assay, transwell chamber assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and flow cytometry. The roles of MTSS1 in PCa progression were demonstrated in vivo by tumor formation assays in nude mice. MTSS1 expression was decreased in PCa tissues in comparison with paired adjacent normal prostate tissues. Compared to the methylation of MTSS1 in normal prostate tissues based on the MethHC website, the MTSS1 in PCa tissues was hypermethylated. The expression of MTSS1 detected by qRT-PCR and western blot analysis was found to be downregulated in PCa cells and tissues. The reduced expression of MTSS1 by small interfering RNA-MTSS1 was recovered by 5-aza-2'-deoxycytidine treatment. Besides, MTSS1 demethylation inhibited migration, invasion, and proliferation of PCa cells, and induced cell cycle to be arrested at G0/G1 phase. Furthermore, it was shown by tumor xenograft assay that MTSS1 inhibited the growth of tumor in vivo. Hypermethylated MTSS1 promoted PCa cells migration, invasion, and proliferation, and suppressed cell cycle arrest at the G0/G1 phase.

13.
Org Lett ; 21(24): 9924-9928, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31789042

RESUMO

The regioselective synthesis of fullerene bis-adducts remains challenging because it produces large amounts of regioisomers. Novel nontethered cis-1 and cis-2 bis(benzofuro)[60]fullerene derivatives were directly synthesized with high regioselectivity by using chlorofullerene C60Cl6 as a precursor. Their structures were determined via spectroscopic data and single-crystal X-ray analysis. A nucleophilic addition elimination mechanism was proposed to elucidate the formation of highly regioselective cis-1 and cis-2 bis-adducts. The potential application of these bis(benzofuro)[60]fullerene derivatives as stabilizers in propellants was also investigated.

14.
Am J Transl Res ; 11(11): 6977-6988, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31814901

RESUMO

Chronic respiratory disorders are some of the most frequent and severe chronic diseases in China. Epidemiological research has shown that particulate matter (PM) is a risk factor and is closely correlated to the progression of numerous respiratory diseases. Fibroblast growth factor 10 (FGF10) is a mesenchymal-epithelial signaling messenger essential for the development and environmental stability of several tissues. Nevertheless, its role in PM-induced airway inflammation remains unclear. The present study aimed to explore the mechanisms underlying the FGF10-related slowing of lung injury and inflammation in vivo and in vitro, as well as the therapeutic potential of these phenomena. Mice were intraperitoneally injected with a vehicle (PBS) or FGF10 (0.5 mg/kg) at one hour before intratracheal treatment with vehicle (PBS) or PM (4 mg/kg) for two consecutive days. Human airway epithelial BEAS-2B cells were exposed to a vehicle (PBS) or FGF10 (10 ng/ml) in vitro at one hour prior to incubation with a vehicle or PM (200 ug/ml) for 24 hours. Then, the impact on inflammatory molecules was investigated. In vivo, it was found that FGF10 diminished the inflammatory cell aggregation and reduced the apoptosis. Interestingly, in the PM group, the level of FGF10 increased in the bronchoalveolar lavage fluid (BALF). However, the pre-treatment with FGF10 markedly impaired the PM-induced increase in IL-6, IL-8, TNF-α and PGE2 levels in BALF and the cell supernatant. In conclusion, the present findings indicate that FGF10 attenuates PM-induced airway inflammation by inhibiting apoptosis and inflammation. This may be exploited for the prevention and management of PM-induced airway inflammation.

15.
Cell Biol Toxicol ; 2019 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-31884678

RESUMO

Particulate matter (PM) is an environmental pollutant closely associated with human airway inflammation. However, the molecular mechanisms of PM-related airway inflammation remains to be fully elucidated. It is known that COX-2/PGE2 play key roles in the pathogenesis of airway inflammation. Filaggrin is a transmembrane protein contributing to tight junction barrier function. As such, Filaggrin prevents leakage of transported solutes and is therefore necessary for the maintenance of epithelial integrity. The objective of the present study was to investigate the regulatory mechanisms of COX-2/PGE2 and Filaggrin upon PM exposure both in vivo and in vitro. C57BL/6 mice received intratracheal instillation of PM for two consecutive days. In parallel, human bronchial epithelial cells (HBECs) were exposed to PM for 24 h. PM exposure resulted in airway inflammation together with upregulation of COX-2/PGE2 and downregulation of Filaggrin in mouse lungs. Corresponding dysregulation of COX-2/PGE2 and Filaggrin was also observed in HBECs subjected to PM. PM exposure led to the phosphorylation of ERK, JNK, and PI3K signaling pathways in a time-dependent manner, while blockade of PI3K with the specific molecular inhibitor LY294002 partially reversed the dysregulation of COX-2/PGE2 and Filaggrin. Moreover, pretreatment of HBECs with NS398, a specific molecular inhibitor of COX-2, and AH6809, a downstream PGE2 receptor inhibitor, reversed the downregulation of Filaggrin upon PM exposure. Taken together, these data demonstrated that the PI3K signaling pathway upregulated COX-2 as well as PGE2 and acted as a pivotal mediator in the downregulation of Filaggrin.

16.
Comput Math Methods Med ; 2019: 9108108, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31781290

RESUMO

In recent years, functional brain network topological features have been widely used as classification features. Previous studies have found that network node scale differences caused by different network parcellation definitions significantly affect the structure of the constructed network and its topological properties. However, we still do not know how network scale differences affect the classification accuracy, performance of classification features, and effectiveness of the feature selection strategy using P values in terms of the machine learning method. This study used five scale parcellations, involving 90, 256, 497, 1003, and 1501 nodes. Three local properties of resting-state functional brain networks were selected (degree, betweenness centrality, and nodal efficiency), and the support vector machine method was used to construct classifiers to identify patients with major depressive disorder. We analyzed the impact of the five scales on classification accuracy. In addition, the effectiveness and redundancy of features obtained by the different scale parcellations were compared. Finally, traditional statistical significance (P value) was verified as a feature selection criterion. The results showed that the feature effectiveness of different scales was similar; in other words, parcellation with more regions did not provide more effective discriminative features. Nevertheless, parcellation with more regions did provide a greater quantity of discriminative features, which led to an improvement in the accuracy of the classification. However, due to the close distance between brain regions, the redundancy of parcellation with more regions was also greater. The traditional P value feature selection strategy is feasible with different scales, but our analysis showed that the traditional P < 0.05 threshold was too strict for feature selection. This study provides an important reference for the selection of network scales when applying topological properties of brain networks to machine learning methods.

17.
Clin Lab ; 65(11)2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31710439

RESUMO

BACKGROUND: Although many advances have been made in the field of molecular biology, new approaches are still required to reveal the molecular mechanisms underlying the pathogenesis of rectal cancer and identify specific diagnostic and therapeutic targets. METHODS: Here, we determined the expression profiles of lncRNA, mRNA, and microRNA (miRNA) in rectal cancer, and constructed the lncRNA-mRNA-miRNA ceRNA networks to identify the hub lncRNAs, mRNAs, and miRNAs involved in this cancer. Moreover, survival analysis was performed to identify survival-related genes. RESULTS: A total of 69 DElncRNAs, 32 DEmiRNAs, and 84 DEmRNAs were included in the ceRNA network. Based on the ceRNA principle, lncRNA ADAMTS9-AS2 was predicted to regulate the expression of FOXF2 gene through competitive binding to miR-182. The result of log-rank test showed that three lncRNAs, five mRNAs, and one miRNA were associated with survival of rectal adenocarcinoma patients and multivariate Cox regression analysis identified four lncRNA signatures as prognostic factors. CONCLUSIONS: These findings add to our understanding on the molecular mechanisms underlying the pathogenesis of rectal cancer and reveal potential diagnostic and therapeutic targets.

18.
Sci Adv ; 5(10): eaax6366, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31633027

RESUMO

Alternative lengthening of telomeres (ALT) is known to use homologous recombination (HR) to replicate telomeric DNA in a telomerase-independent manner. However, the detailed process remains largely undefined. It was reported that nuclear receptors COUP-TFII and TR4 are recruited to the enriched GGGTCA variant repeats embedded within ALT telomeres, implicating nuclear receptors in regulating ALT activity. Here, we identified a function of nuclear receptors in ALT telomere maintenance that involves a direct interaction between COUP-TFII/TR4 and FANCD2, the key protein in the Fanconi anemia (FA) DNA repair pathway. The COUP-TFII/TR4-FANCD2 complex actively induces the DNA damage response by recruiting endonuclease MUS81 and promoting the loading of the PCNA-POLD3 replication complex in ALT telomeres. Furthermore, the COUP-TFII/TR4-mediated ALT telomere pathway does not require the FA core complex or the monoubiquitylation of FANCD2, key steps in the canonical FA pathway. Thus, our findings reveal that COUP-TFII/TR4 regulates ALT telomere maintenance through a novel noncanonical FANCD2 pathway.

19.
Gut ; 2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31582403

RESUMO

OBJECTIVE: N6-methyladenosine (m6A) RNA methylation and its associated methyltransferase METTL3 are involved in tumour initiation and progression via the regulation of RNA function. This study explored the biological function and clinical significance of METTL3 in gastric cancer (GC). DESIGN: The prognostic value of METTL3 expression was evaluated using tissue microarray and immunohistochemical staining analyses in a human GC cohort. The biological role and mechanism of METTL3 in GC tumour growth and liver metastasis were determined in vitro and in vivo. RESULTS: The level of m6A RNA was significantly increased in GC, and METTL3 was the main regulator involved in the abundant m6A RNA modification. METTL3 expression was significantly elevated in GC tissues and associated with poor prognosis. Multivariate Cox regression analysis revealed that METTL3 expression was an independent prognostic factor and effective predictor in human patients with GC. Moreover, METTL3 overexpression promoted GC proliferation and liver metastasis in vitro and in vivo. Mechanistically, P300-mediated H3K27 acetylation activation in the promoter of METTL3 induced METTL3 transcription, which stimulated m6A modification of HDGF mRNA, and the m6A reader IGF2BP3 then directly recognised and bound to the m6A site on HDGF mRNA and enhanced HDGF mRNA stability. Secreted HDGF promoted tumour angiogenesis, while nuclear HDGF activated GLUT4 and ENO2 expression, followed by an increase in glycolysis in GC cells, which was correlated with subsequent tumour growth and liver metastasis. CONCLUSIONS: Elevated METTL3 expression promotes tumour angiogenesis and glycolysis in GC, indicating that METTL3 expression is a potential prognostic biomarker and therapeutic target for human GC.

20.
ACS Omega ; 4(13): 15600-15614, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31572861

RESUMO

The implementation of fuel cell deployment requires efficient conversion of fuels into hydrogen in a distributed energy system. Fortunately, continuous flow and microreactor technology provide unique opportunities for the portable production of hydrogen. This study focuses on determining the operation space for a thermally integrated methane reforming system, thereby providing a theoretical basis for the design and optimization of such systems. The steam-methane reforming over rhodium coupled with methane combustion over platinum in a thermally integrated microchannel reactor arranged with rectangular-shaped protuberances was studied numerically in order to improve its operability and stability. Computational fluid dynamic simulations were carried out with detailed reaction mechanisms to identify conditions for the maximum hydrogen yield and the highest output power. Various operating lines were presented, and various performance metrics were evaluated accordingly. The results indicated that the efficient production of hydrogen is made possible through improving transport performance for highly active catalysts. The flow disturbance elements designed for the reactor are of great benefit to intensification of the reforming process. There exists a trade-off between fuel utilization and output power. Autothermal operation advantages from improved transport performance in small physical dimensions were demonstrated for the system, but careful thermal management is always necessary to ensure its efficient and stable operation. The thermal conductivity of the wall separating the exothermic and endothermic reactions plays a significant role in determining the performance of the system. Highly active catalysts are required to intensify the overall reforming process and to achieve efficient thermal management. Adjustment of fluid velocities can serve as a convenient means to achieve efficient operation of the system.

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