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1.
ACS Appl Mater Interfaces ; 11(43): 39722-39727, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31609103

RESUMO

Electrochemical CO2 reduction (ECR) to highly value-added products is regarded as a promising way to capture and utilize atmospheric CO2. While the large overpotential and low selectivity largely hinder its practical application, it is highly desirable to design promising catalysts for efficient ECR catalysis. Herein, we have designed a series of core/shell Ag/(Amorphous-Sn(IV)) (Ag/(A-Sn(IV))) nanoparticles (NPs) as highly active and selective catalysts for ECR. Precise amorphous shell tuning of Ag/(A-Sn(IV)) NPs reveals that Ag/(A-Sn(IV)) NPs exhibit volcano-like activity and selectivity toward ECR as a function of the thickness of amorphous shells. The ultrathin amorphous shell not only effectively suppressed the hydrogen evolution reaction (HER) to increase the ECR activity but also converted the ECR product from CO to HCOOH as the applied voltage increased. As a consequence, the optimized core/shell Ag75/(A-Sn(IV))25 NPs show outstanding performance with a CO faradaic efficiency (FE) of 88.0% and a partial current density of 7.9 mA/cm2 at -0.7 V and a HCOOH FE of 75.1% and a partial current density of 13.4 mA/cm2 at -0.9 V. It also exhibited negligible change in current density and FE of the main products after a 12 h reaction. Theoretical calculation further confirmed that the regulation of the shell thickness effectively inhibited the HER and enhanced ECR with a 0.6 nm shell thickness of Ag/(A-Sn(IV)) NPs exhibiting the best activity.

2.
Angew Chem Int Ed Engl ; 58(51): 18604-18609, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31535425

RESUMO

The (photo)electrochemical N2 reduction reaction (NRR) provides a favorable avenue for the production of NH3 using renewable energy in mild operating conditions. Understanding and building an efficient catalyst with high NH3 selectivity represents an area of intense interest for the early stages of development for NRR. Herein, we introduce a CoOx layer to tune the local electronic structure of Au nanoparticles with positive valence sites for boosting conversion of N2 to NH3 . The catalysts, possessing high average oxidation states (ca. 40 %), achieve a high NH3 yield rate of 15.1 µg cm-2 h-1 and a good faradic efficiency of 19 % at -0.5 V versus reversible hydrogen electrode. Experimental results and simulations reveal that the ability to tune the oxidation state of Au enables the control of N2 adsorption and the concomitant energy barrier of NRR. Altering the Au oxidation state provides a unique strategy for control of NRR in the production of valuable NH3 .

3.
Angew Chem Int Ed Engl ; 58(41): 14578-14583, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31410914

RESUMO

Sb-based nanocomposites are attractive anode materials for batteries as they exhibit large theoretical capacity and impressive working voltage. However, tardy potassium ion diffusion characteristics, unstable Sb/electrolyte interphase, and huge volume variation pose a challenge, hindering their practical use for potassium-ion batteries (PIBs). Now, a simple robust strategy is presented for uniformly impregnating ultrasmall Sb nanocrystals within carbon nanofibers containing an array of hollow nanochannels (denoted u-Sb@CNFs), resolving the issues above and yielding high-performance PIBs. u-Sb@CNFs can be directly employed as an anode, thereby dispensing with the need for conductive additives and binders. Such a judiciously crafted u-Sb@CNF-based anode renders a set of intriguing electrochemical properties, representing large charge capacity, unprecedented cycling stability, and outstanding rate performance. A reversible capacity of 225 mAh g-1 is retained after 2000 cycles at 1 A g-1 .

4.
Chem Commun (Camb) ; 55(16): 2285-2288, 2019 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-30694288

RESUMO

Herein, we report a heterogeneous single iron atom catalyst exhibiting excellent peroxidase, oxidase and catalase enzyme-like activities (defined as single atom enzymes, SAEs), exceeding those of Fe3O4 nanozymes by a factor of 40. Our findings open up a new family of artificial materials that mimic natural enzymes.


Assuntos
Materiais Biomiméticos/química , Compostos Férricos/química , Nanoestruturas/química , Peroxidase/metabolismo , Catálise , Concentração de Íons de Hidrogênio , Modelos Moleculares , Conformação Molecular
5.
Angew Chem Int Ed Engl ; 58(4): 1019-1024, 2019 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-30479055

RESUMO

Electrocatalysis is dominated by reaction at the solid-liquid-gas interface; surface properties of electrocatalysts determine the electrochemical behavior. The surface charge of active sites on catalysts modulate adsorption and desorption of intermediates. However, there is no direct evidence to bridge surface charge and catalytic activity of active sites. Defects (active sites) were created on a HOPG (highly oriented pyrolytic graphite) surface that broke the intrinsic sp2 -hybridization of graphite by plasma, inducing localization of surface charge onto defective active sites, as shown by scanning ion conductance microscopy (SICM) and Kelvin probe force microscopy (KPFM). An electrochemical test revealed enhanced intrinsic activity by the localized surface charge. DFT calculations confirmed the relationship between surface charge and catalytic activity. This work correlates surface charge and catalytic activity, providing insights into electrocatalytic behavior and guiding the design of advanced electrocatalysts.

6.
Nat Commun ; 9(1): 4933, 2018 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-30467320

RESUMO

While engineering the phase and structure of electrocatalysts could regulate the performance of many typical electrochemical processes, its importance to the carbon dioxide electroreduction has been largely unexplored. Herein, a series of phase and structure engineered copper-tin dioxide catalysts have been created and thoroughly exploited for the carbon dioxide electroreduction to correlate performance with their unique structures and phases. The copper oxide/hollow tin dioxide heterostructure catalyst exhibits promising performance, which can tune the products from carbon monoxide to formic acid at high faradaic efficiency by simply changing the electrolysis potentials from -0.7 VRHE to -1.0 VRHE. The excellent performance is attributed to the abundant copper/tin dioxide interfaces involved in the copper oxide/hollow tin dioxide heterostructure during the electrochemical process, decreasing the reaction free-energies for the formation of COOH* species. Our work reported herein emphasizes the importance of phase and structure modulating of catalysts for enhancing electrochemical CO2 reduction and beyond.

7.
J Am Chem Soc ; 140(38): 12256-12262, 2018 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-30169028

RESUMO

Direct production of H2 from photocatalytic water splitting is a potential solution to environmental pollution and energy crisis, and tremendous efforts have been made to seek efficient photocatalysts that can split pure water (pH = 7) under visible light irradiation. Herein, by means of systematic density functional theory (DFT) computations, we demonstrated that the two-dimensional (2D) PdSeO3 monolayer is a promising candidate. The mechanical exfoliation of PdSeO3 monolayer from its bulk phase is experimentally feasible due to the rather small cleavage energy of ∼0.42 J/m2. Remarkably, PdSeO3 monolayer is semiconducting with a moderate indirect band gap of 2.84 eV, and its valence and conduction bands perfectly engulf the redox potentials of water. In particular, water oxidation and hydrogen reduction half reactions can both occur readily on the different active sites of PdSeO3 monolayer under the potentials solely provided by photogenerated electrons and holes. As PdSeO3 monolayer also has rather pronounced optical absorption in the visible and ultraviolet regions of the solar spectrum, it could be utilized as a highly efficient photocatalyst for splitting pure water into H2 and O2 in a stoichiometric amount of 2:1 without using sacrificial reagents or cocatalysts.

8.
Oncol Lett ; 16(4): 4361-4366, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30214570

RESUMO

Expression level of messenger RNA (mRNA) of cold shock domain protein A intronless pseudogene (CSDAP1) in lung cancer tissues was studied. Fresh pathological specimens collected from 317 patients with primary lung cancer through surgical resection from January 2007 to January 2012 were selected. Reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis were used to detect the transcription and translation of CSDAP1 in lung cancer tissues and cancer-adjacent normal tissues, and the results were analyzed in combination with clinicopathological features and prognosis of lung cancer. Among 317 lung cancer specimens, 105 cases (33.1%) had high expression of CSDAP1. Among 138 cases of pulmonary adenocarcinoma, 59 cases had high expression of CSDAP1, and the high expression rate was 42.8%. Among 170 cases of lung squamous cell carcinoma, 46 cases had high expression of CSDAP1, and the high expression rate was 27.5% (P<0.05). Three cases of large cell carcinoma and 9 cases of small cell carcinoma had extremely low expression or had no expression of CSDAP1. Among the 127 lung cancer patients with regional lymph node metastasis, 53 cases (41.7%) had high expression of CSDAP1, while among the 190 lung cancer patients without regional lymph node metastasis, 52 cases (27.4%) had high expression of CSDAP1 (P<0.05). The results also revealed that the expression of CSDAP1 was also related to tumor-node-metastasis (TNM) staging of lung cancer. One-year, three-year and five-year survival rates of lung cancer patients who had no expression of CSDAP1 were relatively high (P<0.05). The results suggested that CSDAP1 may play an important role in the occurrence, development and judgement of prognosis of lung cancer.

9.
Mediators Inflamm ; 2018: 9031452, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29887758

RESUMO

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is closely associated with airway inflammation including monocytes, lymphocytes, and neutrophils. Monocytes play an essential role in the pathogenesis of chronic obstructive pulmonary disease (COPD). To elucidate the association of circulating monocyte alteration with AECOPD, we analyzed monocyte subpopulation in the peripheral blood of 16 healthy volunteers and 22 AECOPD patients at the stages of admission and remission after clinical therapy. We found a dramatic increase of a previously unreported population of large size circulating atypical monocytes (A Mo) in AECOPD patients, characterized by higher forward scatter and lower side scatter values than the typical monocytes (T Mo) which were observed predominantly in healthy individuals. Further analysis showed that A Mo expressed higher levels of CD16, intercellular adhesion molecule 1 (ICAM-1), and chemotactic protein-1 receptor-2 (CCR2) than T Mo. In contrast, the expression of class II antigen (HLA-DR) by A Mo was lower than T Mo. More importantly, we observed that the percentage of circulating A Mo among total monocytes correlated with the length of hospital stay (time to remission) and disease duration. The data suggest that circulating A Mo might have the potential to serve as a biomarker in the diagnosis and prognosis of AECOPD.


Assuntos
Inflamação/metabolismo , Monócitos/citologia , Monócitos/metabolismo , Doença Pulmonar Obstrutiva Crônica/imunologia , Doença Pulmonar Obstrutiva Crônica/metabolismo , Idoso , Feminino , Citometria de Fluxo , Antígenos HLA-DR/metabolismo , Humanos , Molécula 1 de Adesão Intercelular/metabolismo , Masculino , Pessoa de Meia-Idade , Doença Pulmonar Obstrutiva Crônica/patologia , Receptores CCR2/metabolismo
10.
Angew Chem Int Ed Engl ; 57(28): 8691-8696, 2018 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-29771458

RESUMO

The oxygen evolution reaction (OER) is an ideal model to study the relationship between the activity and the surface properties of catalysts. Defect engineering has been extensively developed to tune the electrocatalytic activity for OER. Compared to the anion vacancies in metal oxides, cation vacancies are more challenging to selectively generate, and the insight into the structure and activity of cation vacancies-rich catalysts are lacked. Herein, using SnCoFe perovskite hydroxide as a precursor, abundant Sn vacancies on the surface were preferentially produced by Ar plasma. Sn vacancies could be preferentially produced as confirmed by the X-ray absorption spectra, probably owing to the lower lattice energy and weaker chemical bonds of Sn(OH)4 . The Sn vacancies promoted the exposure of active CoFe sites, resulting in an amorphous surface layer, modulated the conductivity, and thus enhanced the OER performance.

11.
Angew Chem Int Ed Engl ; 57(31): 9660-9664, 2018 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-29660248

RESUMO

Despite wide applications of bimetallic electrocatalysis in oxygen evolution reaction (OER) owing to their superior performance, the origin of the improved performance remains elusive. The underlying mechanism was explored by designing and synthesizing a series of stable metal-organic frameworks (MOFs: NNU-21-24) based on trinuclear metal carboxylate clusters and tridentate carboxylate ligands. Among the examined stable MOFs, NNU-23 exhibits the best OER performance; particularly, compared with monometallic MOFs, all the bimetallic MOFs display improved OER activity. DFT calculations and experimental results demonstrate that introduction of the second metal atom can improve the activity of the original atom. The proposed model of bimetallic electrocatalysts affecting their OER performance can facilitate design of efficient bimetallic catalysts for energy storage and conversion, and investigation of the related catalytic mechanisms.

12.
Small ; 14(17): e1800136, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29611304

RESUMO

Intrinsically inferior electrocatalytic activity of NiFe layered double hydroxides (LDHs) nanosheets is considered as a limiting factor to inhibit the electrocatalytic properties for oxygen evolution reaction (OER). Proper defect engineering to tune the surface electronic configuration of electrocatalysts may significantly improve the intrinsic activity. In this work, the selective formation of cation vacancies in NiFe LDHs nanosheets is successfully realized. The as-synthesized NiFe LDHs-VFe and NiFe LDHs-VNi electrocatalysts show excellent activity for OER, mainly attributed to the introduction of rich iron or nickel vacancies in NiFe LDHs nanosheets, which efficiently tune the surface electronic structure increasing the adsorbing capacity of OER intermediates. Density functional theory (DFT) computational results also further indicate that the OER catalytic performance of NiFe LDHs can be pronouncedly improved by introducing Fe or Ni vacancies.

13.
World J Surg Oncol ; 16(1): 60, 2018 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-29558957

RESUMO

BACKGROUND: The anti-cancer role of metformin has been reported in many different kinds of solid tumors, but how it affects non-small cell lung cancer (NSCLC) is currently elusive. The aim of this study was to investigate the influence of metformin treatment on diabetic NSCLC. METHODS: Two hundred fifty-five patients of diabetic NSCLC receiving therapy in our hospital from 2014 to 2016 were enrolled in our study. The information on clinical diagnosis, pathology, and prognosis as well as the influence of metformin in diabetic NSCLC were collected and assessed. Univariate and multivariate analytical techniques were applied to explore how metformin affect the survival of NSCLC. RESULTS: One hundred fifty of the 255 diabetic NSCLC patients took metformin. The median overall survival time (OST) and disease-free survival time (DFST) were significantly prolonged with metformin treatment compared to without metformin treatment (OST 25.0 vs 11.5 months, p = 0.005; DFST 15.6 vs 8.5 months, p = 0.010). Multivariate analysis indicated that metformin treatment could be used to predict the long-term outcome of diabetic NSCLC independently (HR = 0.588, 95% CI 0.466-0.895, p = 0.035). CONCLUSION: Our study revealed that the metformin could help in improving the final outcome of NSCLC patients with diabetes in the long term and thus could be applied to treat NSCLC.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/patologia , Carcinoma de Células Escamosas/patologia , Diabetes Mellitus Tipo 2/fisiopatologia , Neoplasias Pulmonares/patologia , Metformina/uso terapêutico , Recidiva Local de Neoplasia/patologia , Idoso , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/epidemiologia , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/epidemiologia , Feminino , Seguimentos , Humanos , Hipoglicemiantes/uso terapêutico , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/epidemiologia , Masculino , Invasividade Neoplásica , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/epidemiologia , Prognóstico , Estudos Retrospectivos , Taxa de Sobrevida
14.
Spectrochim Acta A Mol Biomol Spectrosc ; 173: 817-821, 2017 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-27810773

RESUMO

Carbon dots (CDs) are raising a substantial amount of attention owing to their many unique and novel physicochemical properties. Herein one-pot synthesized CDs, to the best of our knowledge, were first served as the robust nanoprobe for detection tannic acid (TA) based on resonance Rayleigh scattering technique. The as-prepared CDs can combine with TA via hydrogen bond, resulting in remarkable enhancement of scattering signal with no changes in the fluorescence of CDs. Therefore, a novel protocol for TA determination was established and this strategy allowed quantitative detection of TA in the linear range of 0.2-10.0µmolL-1 with an excellent detection limit of 9.0nmolL-1. Moreover, the CDs based nanoprobe can be applied to the determination of TA in water sample with satisfactory results. Our study can potentially influence our current views on CDs and particularly impressive and offers new insights into application of CDs beyond the traditional understanding of CDs.

15.
J Sci Food Agric ; 97(8): 2569-2574, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27714818

RESUMO

BACKGROUND: Using a norfloxacin (NFLX)-Nd3+ -cetyltrimethylammonium bromide (CTAB) system for the detection of NFLX, a simple and sensitive method based on fluorescence enhancement was developed. RESULTS: In pH 7.0 buffer solution, NFLX reacted with Nd3+ to form a complex, which resulted in fluorescence enhancement of NFLX, and the maximum emission peak shifted from 415 nm for NFLX to 450 nm for NFLX-Nd3+ . Moreover, the fluorescence intensity increased further when the surfactant CTAB was added to NFLX-Nd3+ . Under the optimum conditions, the fluorescence intensity of the NFLX-Nd3+ -CTAB system was linearly correlated with the NFLX concentration in the range 0.038-10 µmol L-1 , with a correlation coefficient (R2 ) of 0.9997. The detection limit (3σ/k) was 0.021 µmol L-1 , indicating that this method can be applied to detect trace NFLX levels. The mechanism of fluorescence enhancement is discussed. The method was used to detect NFLX in fish and chicken samples with satisfactory results. CONCLUSION: The present results indicate that this method has the potential for fast and real-time determination of NFLX in food samples © 2016 Society of Chemical Industry.


Assuntos
Antibacterianos/análise , Resíduos de Drogas/análise , Resíduos de Drogas/isolamento & purificação , Contaminação de Alimentos/análise , Carne/análise , Norfloxacino/análise , Espectrometria de Fluorescência/métodos , Animais , Galinhas , Peixes
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 167: 106-110, 2016 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-27262658

RESUMO

Fluorescent carbon dots was prepared by heating N-(2-hydroxyethyl)ethylene diaminetriacetic acid in air. The carbon dots were not only highly soluble in water but also uniform in size, and possessed strong blue fluorescence and excitation wavelength-dependent emission properties with the maximum excitation and emission wavelength at 366nm and 423nm, respectively. Food colorant sunset yellow whose excitation and emission wavelength at 303nm and 430nm could selectively quench the fluorescence of carbon dots, efficient fluorescent resonance energy transfer between the carbon dots and sunset yellow is achieved. This was exploited to design a method for the determination of sunset yellow in the concentration range from 0.3 to 8.0µmolL(-1), with a limit of detection (3σ/k) of 79.6nmolL(-1). Furthermore the fluorimetric detection method was established and validated for sunset yellow in soft drinks samples with satisfactory results.


Assuntos
Compostos Azo/análise , Carbono/química , Bebidas Gaseificadas/análise , Transferência Ressonante de Energia de Fluorescência/métodos , Corantes Fluorescentes/química , Corantes de Alimentos/análise , Pontos Quânticos/química , Análise de Alimentos/métodos , Limite de Detecção , Pontos Quânticos/ultraestrutura
17.
J Org Chem ; 81(7): 3023-30, 2016 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-26959867

RESUMO

Highly enantioselective Friedel-Crafts C2-alkylation reactions of 3-substituted indoles with α,ß-unsaturated esters and nitroalkenes were developed using chiral Lewis acids as catalysts, which afforded chiral indole derivatives bearing C2-benzylic stereogenic centers in good to excellent yields (up to 99%) and enantioselectivities (up to 96% ee).

18.
Spectrochim Acta A Mol Biomol Spectrosc ; 161: 95-100, 2016 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-26963730

RESUMO

Based on L-tryptophan-Pd(II) system, a sensitive and selective fluorimetric assay for the quantification of ceftriaxone (CTRX) had been developed. The experimental results showed that in pH 4.0 Britton-Robinson (BR) buffer medium, the fluorescence of L-tryptophan (L-Trp) (λex/λem=276 nm/352 nm) could be efficiently quenched by Pd(II). When CTRX was added to the mixed solution of the L-tryptophan and Pd(II), the fluorescence of L-Trp recovered. The reaction mechanism and the reasons for the fluorescence recovery were also discussed. Pd(II) reacted with L-Trp to form a 1:1 chelate complex, and then, after CTRX was added in L-Try-Pd(II) system, the ligand exchange reaction occurred between L-Trp and CTRX, which resulted in the fluorescence recovery. Under the optimized experimental conditions, the recovered fluorescence intensities at 352 nm showed excellent linear relationship with the concentration of CTRX over the range of 6.0 × 10(-8)-2.4 × 10(-)(6) mol L(-1) (0.040-1.59 µg mL(-1)). The correlation coefficient (R) was 0.9997 and the detection limit was 1.8 × 10(-8) mol L(-1) (11.9 ng mL(-1)). Furthermore, the assay had been applied to determine trace amount of CTRX human urine samples with satisfactory results.


Assuntos
Antibacterianos/urina , Ceftriaxona/urina , Complexos de Coordenação/química , Corantes Fluorescentes/química , Paládio/química , Triptofano/química , Fluorescência , Humanos , Limite de Detecção , Espectrometria de Fluorescência/métodos
19.
Environ Monit Assess ; 187(11): 658, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26427844

RESUMO

In the present study, a novel triple-wavelength overlapping resonance Rayleigh scattering (TWO-RRS) method had been well established to detect perfluorooctane sulfonate (PFOS). We found that crystal violet (CV) could react with PFOS to form 1:1 ion-association complex by electrostatic attraction and hydrophobic effect over a wide pH range (5.0∼11.0) in less than 60 s. The complexes would further self-aggregated into nanoparticles [CV-PFOS]n. Based on this phenomenon, not only the absorption and Raman spectra were changed but also the resonance Rayleigh scattering (RRS) intensities were significantly enhanced. And three new RRS peaks located at 327, 492, and 654 nm were clearly observed, respectively. At the same time, it was found that both the enhanced single-wavelength resonance Rayleigh scattering (SW-RRS) and TWO-RRS intensities against the concentration of PFOS showed an excellent correlation. The detection limits for the three single peaks were 27.4 nmol L(-1) (13.7 µg L(-1), 327 nm), 27.5 nmol L(-1) (13.8 µg L(-1), 492 nm), and 31.4 nmol L(-1) (15.7 µg L(-1), 654 nm), and for TWO-RRS method was 5.9 nmol L(-1) (3.0 µg L(-1)). Moreover, it could be applied to determine PFOS water samples successfully.


Assuntos
Ácidos Alcanossulfônicos/química , Fluorcarbonetos/química , Bioensaio , Monitoramento Ambiental , Interações Hidrofóbicas e Hidrofílicas , Espalhamento de Radiação
20.
Cell Cycle ; 14(12): 1823-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25945611

RESUMO

p53 tumor-suppressor gene is a master transcription factor which controls cell cycle progression and apoptosis. killin was discovered as one of the p53 target genes implicated in S-phase control coupled to cell death. Due to its extreme proximity to pten tumor-suppressor gene on human chromosome 10, changes in epigenetic modification of killin have also been linked to Cowden syndrome as well as other human cancers. Previous studies revealed that Killin is a high-affinity DNA-binding protein with preference to single-stranded DNA, and it inhibits DNA synthesis in vitro and in vivo. Here, co-localization studies of RFP-Killin with either GFP-PCNA or endogenous single-stranded DNA binding protein RPA during S-phase show that Killin always adopts a mutually exclusive punctuated nuclear expression pattern with the 2 accessory proteins in DNA replication. In contrast, when cells are not in S-phase, RFP-Killin largely congregates in the nucleolus where rRNA transcription normally occurs. Both of these cell cycle specific localization patterns of RFP-Killin are stable under high salt condition, consistent with Killin being tightly associated with nucleic acids within cell nuclei. Together, these cell biological results provide a molecular basis for Killin in competitively inhibiting the formation of DNA replication forks during S-phase, as well as potentially negatively regulate RNA synthesis during other cell cycle phases.


Assuntos
Ciclo Celular , Replicação do DNA , DNA/biossíntese , Regulação da Expressão Gênica , RNA/biossíntese , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo , Animais , Células COS , Nucléolo Celular/metabolismo , Cromossomos/genética , DNA de Cadeia Simples/genética , Epigênese Genética , Humanos , Proteínas Luminescentes/metabolismo , Microscopia de Fluorescência , Plasmídeos/metabolismo , Antígeno Nuclear de Célula em Proliferação/metabolismo , Fase S , Proteína Supressora de Tumor p53/genética
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