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1.
ACS Appl Mater Interfaces ; 16(25): 31922-31935, 2024 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-38874539

RESUMO

Poly-l-lysine (PLL) and Matrigel, both classical coating materials for culture substrates in neural stem cell (NSC) research, present distinct interfaces whose effect on NSC behavior at cellular and molecular levels remains ambiguous. Our investigation reveals intriguing disparities: although both PLL and Matrigel interfaces are hydrophilic and feature amine functional groups, Matrigel stands out with lower stiffness and higher roughness. Based on this diversity, Matrigel surpasses PLL, driving NSC adhesion, migration, and proliferation. Intriguingly, PLL promotes NSC differentiation into astrocytes, whereas Matrigel favors neural differentiation and the physiological maturation of neurons. At the molecular level, Matrigel showcases a wider upregulation of genes linked to NSC behavior. Specifically, it enhances ECM-receptor interaction, activates the YAP transcription factor, and heightens glycerophospholipid metabolism, steering NSC proliferation and neural differentiation. Conversely, PLL upregulates genes associated with glial cell differentiation and amino acid metabolism and elevates various amino acid levels, potentially linked to its support for astrocyte differentiation. These distinct transcriptional and metabolic activities jointly shape the divergent NSC behavior on these substrates. This study significantly advances our understanding of substrate regulation on NSC behavior, offering novel insights into optimizing and targeting the application of these surface coating materials in NSC research.


Assuntos
Diferenciação Celular , Proliferação de Células , Colágeno , Combinação de Medicamentos , Laminina , Células-Tronco Neurais , Polilisina , Proteoglicanas , Polilisina/química , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/efeitos dos fármacos , Laminina/química , Laminina/farmacologia , Colágeno/química , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Proteoglicanas/química , Proteoglicanas/farmacologia , Animais , Adesão Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Camundongos
2.
J Hazard Mater ; 476: 134894, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38909463

RESUMO

Consumed VOCs are the compounds that have reacted to form ozone and secondary organic aerosol (SOA) in the atmosphere. An approach that can apportion the contributions of primary sources and reactions to the consumed VOCs was developed in this study and applied to hourly VOCs data from June to August 2022 measured in Shijiazhuang, China. The results showed that petrochemical industries (36.9 % and 51.7 %) and oxidation formation (20.6 % and 35.6 %) provided the largest contributions to consumed VOCs and OVOCs during the study period, whereas natural gas (5.0 % and 7.6 %) and the mixed source of liquefied petroleum gas and solvent use (3.1 % and 4.2 %) had the relatively low contributions. Compared to the non-O3 pollution (NOP) period, the contributions of oxidation formation, petrochemical industries, and the mixed source of gas evaporation and vehicle emissions to the consumed VOCs during the O3 pollution (OP) period increased by 2.8, 3.8, and 9.3 times, respectively. The differences in contributions of liquified petroleum gas and solvent use, natural gas, and combustion sources to consumed VOCs between OP and NOP periods were relatively small. Transport of petrochemical industries emissions from the southeast to the study site was the primary consumed pathway for VOCs emitted from petrochemical industries.

3.
J Gene Med ; 26(5): e3687, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38690623

RESUMO

BACKGROUND: Bones undergo a constant remodeling, a process involving osteoclast-mediated bone resorption and osteoblast-mediated bone formation, crucial for maintaining healthy bone mass. We previously observed that miR-185 depletion may promote bone formation by regulating Bgn expression and the BMP/Smad signaling pathway. However, the effects of miR-185-5p on the osteoclasts and bone remodeling have not been elucidated, warranting further exploration. METHODS: Tartrate-resistant acid phosphatase staining was utilized to assess the differentiation ability of bone marrow mononuclear macrophages (BMMs) from mmu-miR-185 gene knockout (KO) mice and wild-type (WT) mice. A reverse transcriptase-quantitative PCR was conducted to compare differences in miR-185-5p and osteoclast marker molecules, including Trap, Dcstamp, Ctsk and Nfatc1, between the KO group and WT group BMMs. Western blot analysis was employed to observe the expression of osteoclast marker molecules. A cell-counting kit-8 was used to analyze cell proliferation ability. Transwell experiments were conducted to detect cell migration. Dual-luciferase reporter assays were employed to confirm whether Btk is a downstream target gene of miR-185-5p. RESULTS: miR-185 depletion promoted osteoclast differentiation in bone marrow-derived monocytes/macrophages. Overexpression of miR-185-5p in RAW264.7 cells inhibited differentiation and migration of osteoclasts. Furthermore, Btk was identified as a downstream target gene of miR-185-5p, suggesting that miR-185-5p may inhibit osteoclast differentiation and migration by targeting Btk. CONCLUSIONS: miR-185 regulates osteoclasts differentiation, with overexpression of miR-185-5p inhibiting osteoclast differentiation and migration in vitro. Additionally, miR-185-5p may modulate osteoclastic differentiation and migration by regulating Btk expression.


Assuntos
Tirosina Quinase da Agamaglobulinemia , Diferenciação Celular , Movimento Celular , Camundongos Knockout , MicroRNAs , Osteoclastos , Animais , MicroRNAs/genética , MicroRNAs/metabolismo , Osteoclastos/metabolismo , Osteoclastos/citologia , Diferenciação Celular/genética , Movimento Celular/genética , Camundongos , Tirosina Quinase da Agamaglobulinemia/metabolismo , Tirosina Quinase da Agamaglobulinemia/genética , Proliferação de Células/genética , Regulação da Expressão Gênica , Macrófagos/metabolismo , Transdução de Sinais , Osteogênese/genética
4.
Mater Today Bio ; 20: 100658, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37214553

RESUMO

Bilirubin, an open chain tetrapyrrole, has powerful antioxidant, anti-inflammatory, immuno-suppressive, metabolic-modulating and anti-proliferative activities. Bilirubin is a natural molecule that is produced and metabolized within the human body, making it highly biocompatible and well suited for clinical use. However, the use of bilirubin has been hampered by its poor water solubility and instability. With advanced construction strategies, bilirubin-derived nanoparticles (BRNPs) have not only overcome the disadvantages of bilirubin but also enhanced its therapeutic effects by targeting damaged tissues, passing through physiological barriers, and ensuring controlled sustained release. We review the mechanisms underlying the biological activities of bilirubin, BRNP preparation strategies and BRNP applications in various disease models. Based on their superior performance, BRNPs require further exploration of their efficacy, biodistribution and long-term biosafety in nonhuman primate models that recapitulate human disease to promote their clinical translation.

5.
Front Cell Neurosci ; 17: 1136250, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37025700

RESUMO

In the past several decades, bilirubin has attracted great attention for central nervous system (CNS) toxicity in some pathological conditions with severely elevated bilirubin levels. CNS function relies on the structural and functional integrity of neural circuits, which are large and complex electrochemical networks. Neural circuits develop from the proliferation and differentiation of neural stem cells, followed by dendritic and axonal arborization, myelination, and synapse formation. The circuits are immature, but robustly developing, during the neonatal period. It is at the same time that physiological or pathological jaundice occurs. The present review comprehensively discusses the effects of bilirubin on the development and electrical activity of neural circuits to provide a systematic understanding of the underlying mechanisms of bilirubin-induced acute neurotoxicity and chronic neurodevelopmental disorders.

6.
Small ; 19(34): e2301516, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37086123

RESUMO

Proton exchange membrane water electrolyzer (PEMWE) is a green hydrogen production technology that can be coupled with intermittent power sources such as wind and photoelectric power. To achieve cost-effective operations, low noble metal loading on the anode catalyst layer is desired. In this study, a catalyst with RuO2 nanorods coated outside SnO2 nanocubes is designed, which forms continuous networks and provides high conductivity. This allows for the reduction of Ru contents in catalysts. Furthermore, the structure evolutions on the RuO2 surface are carefully investigated. The etched RuO2 surfaces are seen as the consequence of Co leaching, and theoretical calculations demonstrate that it is more effective in driving oxygen evolution. For electrochemical tests, the catalysts with 23 wt% Ru exhibit an overpotential of 178 mV at 10 mA cm-2 , which is much higher than most state-of-art oxygen evolution catalysts. In a practical PEMWE, the noble metal Ru loading on the anode side is only 0.3 mg cm-2 . The cell achieves 1.61 V at 1 A cm-2 and proper stability at 500 mA cm-2 , demonstrating the effectiveness of the designed catalyst.

7.
Nanotechnology ; 33(19)2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-35090146

RESUMO

Rational design is essential in the synthesis of electrocatalysts for the oxygen reduction reaction (ORR). Herein, we introduced zeolitic imidazolate framework-8 (ZIF-8) and polyvinyl pyrrolidone (PVP) into the electrospinning process of the polyacrylonitrile (PAN) and hemin to increase the active site loading and exposed active area of the final product with empty bead-like structures. In this method, ZIF-8 acts as a carbon skeleton to provide a rich microporous structure that can support active sites, and as a nitrogen dopant to improve nitrogen contents. PVP changes the properties of the spinning solution, adjusts the fiber morphology, and to increase the exposed area of active sites as a pore former. The obtained Fe-N-C ORR catalyst delivered a half-wave potential (E1/2) of 0.924 V in a 0.1 M KOH solution and 0.77 V in a 0.1 M HClO4solution. A homemade zinc air battery with power density of 236 mW cm-2demonstrated the excellent performance of the catalyst under working conditions.

8.
ACS Appl Mater Interfaces ; 13(30): 35856-35864, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34292710

RESUMO

The electrochemical production of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (ORR) can realize the customer-oriented onsite synthesis of H2O2 in a green and sustainable method. The ongoing challenge that needs to be solved is the fabrication of robust electrocatalysts of excellent performance. In this work, C60 was selected as a precursor due to its uniform structure and abundant pentagon rings. Thanks to the strong interaction between C60 and thiophene, after heteromolecule assembly in the liquid reaction and subsequent reconstruction of the carbon topological structure in solid calcination, C60 was successfully transformed into polyhedral carbon micro-nano shells (PCMNS) with an effective pore structure for the first time, which exhibited excellent capacity for production of H2O2 via two-electron ORR, especially in neutral media. In addition to the high onset potential (0.49 V vs reversible hydrogen electrode (RHE)) and low Tafel slope (72 mV dec-1), its selectivity reached >90% within the potential range of 0.30-0.45 V and maintained >80% after constant potential electrolysis for 10 h. The yield rate of H2O2 was 1102.5 mmol gcat-1 h-1, determined by an H-type electrolytic cell, which was one of the highest values of metal-free carbon-based ORR electrocatalysts ever reported. Such excellent two-electron ORR performance of PCMNS was attributed to its abundant accessible active sites and hierarchical pore structures.

9.
Cell Death Dis ; 12(7): 622, 2021 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-34135314

RESUMO

Accumulated evidence shows that OGT-mediated O-GlcNAcylation plays an important role in response to DNA damage repair. However, it is unclear if the "eraser" O-GlcNAcase (OGA) participates in this cellular process. Here, we examined the molecular mechanisms and biological functions of OGA in DNA damage repair, and found that OGA was recruited to the sites of DNA damage and mediated deglycosylation following DNA damage. The recruitment of OGA to DNA lesions is mediated by O-GlcNAcylation events. Moreover, we have dissected OGA using deletion mutants and found that C-terminal truncated OGA including the pseudo HAT domain was required for the recruitment of OGA to DNA lesions. Using unbiased protein affinity purification, we found that the pseudo HAT domain was associated with DNA repair factors including NONO and the Ku70/80 complex. Following DNA damage, both NONO and the Ku70/80 complex were O-GlcNAcylated by OGT. The pseudo HAT domain was required to recognize NONO and the Ku70/80 complex for their deglycosylation. Suppression of the deglycosylation prolonged the retention of NONO at DNA lesions and delayed NONO degradation on the chromatin, which impaired non-homologus end joining (NHEJ). Collectively, our study reveals that OGA-mediated deglycosylation plays a key role in DNA damage repair.


Assuntos
Antígenos de Neoplasias/metabolismo , Núcleo Celular/enzimologia , Dano ao DNA , Reparo do DNA por Junção de Extremidades , Proteínas de Ligação a DNA/metabolismo , Histona Acetiltransferases/metabolismo , Hialuronoglucosaminidase/metabolismo , Autoantígeno Ku/metabolismo , Processamento de Proteína Pós-Traducional , Proteínas de Ligação a RNA/metabolismo , Antígenos de Neoplasias/genética , Linhagem Celular Tumoral , Núcleo Celular/genética , Núcleo Celular/efeitos da radiação , Proliferação de Células , Proteínas de Ligação a DNA/genética , Glicosilação , Células HEK293 , Histona Acetiltransferases/genética , Humanos , Hialuronoglucosaminidase/genética , Autoantígeno Ku/genética , Domínios Proteicos , Proteínas de Ligação a RNA/genética , Especificidade por Substrato
10.
Lab Chip ; 21(12): 2398-2406, 2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-33960344

RESUMO

COVID-19 is a new strain of highly contagious coronavirus, and at present, more than 221.4 million people have been infected with this virus, and the death toll exceeds 2793398. Early and fast detection of COVID-19 from infected individuals is critical to limit its spreading. Here, we report an innovative approach to detect the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N) protein by combining DNA/RNA oligomers as aptamers and a graphene oxide (GO) coated optical microfiber as a sensor system. The DNA/RNA aptamers can effectively capture the SARS-CoV-2 N protein in vitro, with the GO coated optical microfiber aptasensor for real-time monitoring of the SARS-CoV-2 N protein. Due to the extremely high surface-to-volume ratio and excellent optical and biochemical properties of the GO surface layer, the fixing effect of the microfiber surface is significantly improved and the lowest limit of detection (LOD) is 6.25 × 10-19 M. Furthermore, in order to prove the feasibility of this sensing method in clinical applications, we use this sensor to detect the N protein mixed in fetal bovine serum (FBS) samples. The experimental results show that the biosensor can quickly and effectively detect the N protein (1 × 10-9 M) in a complex sample matrix within 3 minutes. These findings suggest that this approach can be utilized for quantitative monitoring of coronavirus particles due to its high sensitivity, which can help to quickly exclude patients who do not have the infection. Collectively, the optical microfiber sensor system could be expected to become an important platform for the diagnosis of coronavirus due to its simple detection scheme and easy miniaturization.


Assuntos
COVID-19 , Grafite , Humanos , Limite de Detecção , SARS-CoV-2
11.
Nanotechnology ; 32(30)2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33862613

RESUMO

The utilization of earth abundant iron and nitrogen doped carbon as a precious-metal-free electrocatalyst for oxygen reduction reaction (ORR) significantly depends on the rational design and construction of desired Fe-Nxmoieties on carbon substrates, which however remains an enormous challenge. Herein a typical nanoporous nitrogen-rich single atom Fe-N/C electrocatalyst on carbon nanotube (NR-CNT@FeN-PC) was successfully prepared by using CNT as carbon substrate, polyaniline (PANI) and dicyandiamine (DCD) as binary nitrogen sources and silica-confinement-assisted pyrolysis, which not only facilitate rich N-doping for the inhibition of the Fe agglomeration and the formation of single atom Fe-Nxsites in carbon matrix, but also generate more micropores for enlarging BET specific surface area (up to 1500 m2·g-1). Benefiting from the advanced composition, nanoporous structure and surface hydrophilicity to guarantee the sufficient accessible active sites for ORR, the NR-CNT@FeN-PC catalyst under optimized conditions delivers prominent ORR performance with a half-wave potential (0.88 V versus RHE) surpass commercial Pt/C catalyst by 20 mV in alkaline electrolyte. When assembled in a home-made Zn-air battery device as cathodic catalyst, it achieved a maximum output power density of 246 mW·cm-2and a specific capacity of 719 mA·h·g-1Znoutperformed commercial Pt/C catalyst, holding encouraging promise for the application in metal-air batteries.

12.
J Mol Cell Biol ; 12(2): 113-124, 2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-31152661

RESUMO

p53 is a key transcription factor to regulate gene transcription. However, the molecular mechanism of chromatin-associated p53 on gene transcription remains elusive. Here, using unbiased protein affinity purification, we found that the RNF20/40 complex associated with p53 on the chromatin. Further analyses indicated that p53 mediated the recruitment of the RNF20/40 complex to p53 target gene loci including p21 and PUMA loci and regulated the transcription of p21 and PUMA via the RNF20/40 complex-dependent histone H2B ubiquitination (ubH2B). Lacking the RNF20/40 complex suppressed not only ubH2B but also the generation of the mature mRNA of p21 and PUMA. Moreover, ubH2B was recognized by the ubiquitin-binding motif of pre-mRNA processing splicing factor 8 (PRPF8), a subunit in the spliceosome, and PRPF8 was required for the maturation of the mRNA of p21 and PUMA. Our study unveils a novel p53-dependent pathway that regulates mRNA splicing for tumor suppression.


Assuntos
Splicing de RNA/genética , RNA Mensageiro/metabolismo , Transcrição Gênica/genética , Proteína Supressora de Tumor p53/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Regulação Neoplásica da Expressão Gênica , Células HCT116 , Humanos , Células K562 , Domínios e Motivos de Interação entre Proteínas , Interferência de RNA , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Proteína Supressora de Tumor p53/química , Proteína Supressora de Tumor p53/genética , Ubiquitina-Proteína Ligases/química , Ubiquitina-Proteína Ligases/genética , Ubiquitinação/genética
13.
Nat Commun ; 10(1): 170, 2019 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-30622280

RESUMO

The original version of this Article contained an error in the author affiliations. Xiaochun Yu was incorrectly associated with College of Life Sciences, Hebei University, Baoding 071000 Hebei, China.This has now been corrected in both the PDF and HTML versions of the Article.

14.
Materials (Basel) ; 12(2)2019 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-30669561

RESUMO

This paper proposes a simple reactive melt infiltration process to improve the mechanical properties of silicon carbide (SiC) ceramics. SiC matrix composites were infiltrated by Al⁻Si (10 wt.%)⁻xTi melts at 900 °C for 4 h. The effects of Ti addition on the microstructure and mechanical properties of the composites were investigated. The results showed that the three-point bending strength, fracture toughness (by single-edge notched beam test), and fracture toughness (by Vickers indentation method) of the SiC ceramics increased most by 34.3%, 48.5%, and 128.5%, respectively, following an infiltration with the Al⁻Si (10 wt.%)⁻Ti (15 wt.%) melt. A distinct white reaction layer mainly containing a Ti3Si(Al)C2 phase was formed on the surface of the composites infiltrated by Al alloys containing Ti. Ti⁻Al intermetallic compounds were scattered in the inner regions of the composites. With the increase in the Ti content (from 0 to 15 wt.%) in the Al alloy, the relative contents of Ti3Si(Al)C2 and Ti⁻Al intermetallic compounds increased. Compared with the fabricated composite infiltrated by an Al alloy without Ti, the fabricated composites infiltrated by Al alloys containing Ti showed improved overall mechanical properties owing to formation of higher relative content Ti3Si(Al)C2 phase and small amounts of Ti⁻Al intermetallic compounds.

15.
Nat Commun ; 9(1): 2689, 2018 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-30002377

RESUMO

53BP1 performs essential functions in DNA double-strand break (DSB) repair and it was recently reported that Tudor interacting repair regulator (TIRR) negatively regulates 53BP1 during DSB repair. Here, we present the crystal structure of the 53BP1 tandem Tudor domain (TTD) in complex with TIRR. Our results show that three loops from TIRR interact with 53BP1 TTD and mask the methylated lysine-binding pocket in TTD. Thus, TIRR competes with histone H4K20 methylation for 53BP1 binding. We map key interaction residues in 53BP1 TTD and TIRR, whose mutation abolishes complex formation. Moreover, TIRR suppresses the relocation of 53BP1 to DNA lesions and 53BP1-dependent DNA damage repair. Finally, despite the high-sequence homology between TIRR and NUDT16, NUDT16 does not directly interact with 53BP1 due to the absence of key residues required for binding. Taken together, our study provides insights into the molecular mechanism underlying TIRR-mediated suppression of 53BP1-dependent DNA damage repair.


Assuntos
Proteínas de Transporte/metabolismo , Quebras de DNA de Cadeia Dupla , Reparo do DNA , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/metabolismo , Ligação Competitiva , Proteínas de Transporte/química , Proteínas de Transporte/genética , Cristalografia por Raios X , DNA/genética , DNA/metabolismo , Dano ao DNA , Células HEK293 , Histonas/metabolismo , Humanos , Lisina/metabolismo , Metilação , Mutação , Ligação Proteica , Proteínas de Ligação a RNA , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/química , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/genética
16.
Cell Death Dis ; 9(6): 578, 2018 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-29784961

RESUMO

Sarcodon imbricatus, a rare medicinal and edible fungus, has various pharmacological bioactivities. We investigated the effects of S. imbricatus polysaccharides (SIPS) on hematopoietic function and identified the underlying mechanisms using in vitro experiments with CHRF, K562, and bone marrow mononuclear cells (BMMNCs) and in vivo experiments with a mouse model of cyclophosphamide-induced hematopoietic dysfunction. We found that SIPS induced proliferation and differentiation of CHRF and K562 cells and upregulated the expression of hematopoietic-related proteins, including p90 ribosomal S6 kinases (RSK1p90), c-Myc, and ETS transcription factor, in the two cell lines. After 28 days of treatment, SIPS enhanced the bodyweight and thymus indices of the mice, alleviated enlargement of the spleen and liver, and contributed to the recovery of peripheral blood to normal levels. More importantly, the percentages of B lymphocytes and hematopoietic stem cells or hematopoietic progenitor cells were significantly elevated in bone marrow. Based on an antibody chip analysis and enzyme-linked immunosorbent assay, SIPS were found to successfully regulate 12 cytokines to healthy levels in serum and spleen. The cytokines included the following: interleukins 1Ra, 2, 3, 4, 5, and 6, tumor necrosis factor α, interferon-γ, granulocyte colony-stimulating factor (G-CSF) and macrophage colony-stimulating factor (M-CSF), C-C motif chemokine1, and monocyte chemoattractant protein-1. Moreover, SIPS upregulated the phosphorylation levels of janus kinase 2 (JAK2) and the signal transducer and activator of transcription 3 (STAT3) in the spleen, and similar results were validated in CHRF cells, K562 cells, and BMMNCs. The data indicate that SIPS activated the JAK2/STAT3 pathway, possibly by interactions among multiple cytokines, particularly G-CSF. We found that SIPS was remarkably beneficial to the bone marrow hematopoietic system, and we anticipate that it could improve myelosuppression induced by long-term radiotherapy or chemotherapy.


Assuntos
Ciclofosfamida/toxicidade , Fungos/química , Fator Estimulador de Colônias de Granulócitos/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Janus Quinase 2/metabolismo , Polissacarídeos/farmacologia , Fator de Transcrição STAT3/metabolismo , Animais , Peso Corporal/efeitos dos fármacos , Células da Medula Óssea/citologia , Células da Medula Óssea/efeitos dos fármacos , Células da Medula Óssea/metabolismo , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Citocinas/sangue , Hematopoese/efeitos dos fármacos , Células-Tronco Hematopoéticas/efeitos dos fármacos , Humanos , Células K562 , Masculino , Camundongos Endogâmicos BALB C , Transdução de Sinais/efeitos dos fármacos , Baço/metabolismo
17.
Biochem Biophys Res Commun ; 484(1): 40-44, 2017 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-28109884

RESUMO

YfeX from Escherichia coli O157 is a bacterial dye-decolorizing peroxidase that represents both dye-decoloring activity and typical peroxidase activity. We reported the crystal structure of YfeX bound to heme at 2.09 Å resolution. The YfeX monomer resembles a ferredoxin-like fold and contains two domains. The three conserved residues surrounding the heme group are His215, Asp143 and Arg232. His215 functions as the proximal axial ligand of the heme iron atom. Biochemical data show that the catalytic significance of the conserved Asp143 and Arg232 depends on the substrate types and that YfeX may adopt various catalytic mechanisms toward divergent substrates. In addition, it is observed that an access tunnel spans from the protein molecular surface to the heme distal region, it serves as the passageway for the entrance and binding of the H2O2.


Assuntos
Arginina/metabolismo , Ácido Aspártico/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Cor , Escherichia coli O157/metabolismo , Proteínas de Escherichia coli/metabolismo , Calorimetria , Domínio Catalítico , Proteínas de Transporte de Cátions/química , Cristalografia por Raios X , Proteínas de Escherichia coli/química , Heme/metabolismo , Peróxido de Hidrogênio/metabolismo , Especificidade por Substrato
18.
Protein Pept Lett ; 24(2): 181-187, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-27894248

RESUMO

Peptidoglycan (PG) is an essential component of the cell wall, and undergoes reconstruction by various PG hydrolases during cell growth, development and division. The murein- tripeptide (Mtp) amidase MpaA belongs to PG hydrolase family and is responsible for cleaving the γ-D-Glumeso- Dap amide bond in the Mtp released during PG turnover. The current paper reports the crystal structure of MpaA from Escherichia coli (E. coli) O157 at 2.6 Å resolution. The asymmetric unit consists of two protein molecules and each monomer represents the common α/ß fold of metallocarboxypeptidases (MCP). The Tyr133-Asp143 loop appears to mediate the entrance and binding of the substrate into the active groove. A structural comparison of MpaA with its homologue from Vibrio harveyi showed that MpaA has narrower active pocket entrance with a smaller surface opening, which is determined by the Val204-Thr211 loop. The reported structure provides a starting point for the molecular mechanism of MpaA in a significant human pathogen.


Assuntos
Clonagem Molecular/métodos , Endopeptidases/química , Endopeptidases/genética , Escherichia coli O157/enzimologia , Domínio Catalítico , Cristalografia por Raios X , Endopeptidases/metabolismo , Escherichia coli O157/química , Escherichia coli O157/genética , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Modelos Moleculares , Peptidoglicano , Ligação Proteica , Estrutura Secundária de Proteína
19.
FEBS Lett ; 590(8): 1262-9, 2016 04.
Artigo em Inglês | MEDLINE | ID: mdl-27001440

RESUMO

EcL-DER, the aspartate/glutamate racemase from the pathogen Escherichia coli O157, exhibits racemase activity for l-aspartate and l-glutamate. This study reports the crystal structures of apo-EcL-DER, the EcL-DER-l-aspartate and the EcL-DER-d-aspartate complexes. The EcL-DER structure contains two domains, forming pseudo-mirror symmetry in the active site. A unique catalytic pair consisting of Thr(83) and Cys(197) exists in the active site. The characteristic conformations of l-Asp and d-Asp in the active site provide a straight structural evidence for the racemization mechanism of EcL-DER. In addition, the diversity of catalytic pairs implies that PLP-independent amino acid racemases adopt various catalytic mechanisms and are classified into different subgroups.


Assuntos
Isomerases de Aminoácido/química , Escherichia coli O157/enzimologia , Isomerases de Aminoácido/metabolismo , Sequência de Aminoácidos , Biocatálise , Domínio Catalítico , Cristalografia por Raios X , Estereoisomerismo , Especificidade por Substrato
20.
Int J Clin Exp Med ; 8(3): 4533-8, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26064380

RESUMO

Surgery entails radical resection, neck dissection and tongue reconstruction has been commonly used in treatment of T2 and T3 tongue squamous cell carcinoma. Although lateral upper arm free flap (LUFF) and radial forearm free flap (RFFF) are similar in texture and thickness, significant differences can be noticed in the donor-site function and surgical demands. In the treatment of T2 and T3 tongue cancer, the choice of either LUFF or RFFF is still not defined.We aim to investigatethe long-term QOL of patients with moderate tongue defect and reconstruction with LUFF or RFFF, based on which to provide clinical suggestion for tongue reconstructions.Sixty-five patients (T2 or T3 stage, 42 underwent tongue reconstruction with RFFF and 23 with LUFF) treated at the Department of Oral and Maxillofacial Surgery, Hospital of Stomatology, Sun Yat-Sen University from January 2005 to June 2009 were included. The QOL of each patient was determined using the questionnaire designed based on the University of Washington Quality-of-Life (UW-QOL, version 4). The questionnaire was accomplished by a qualified medical staff blinded to the study after telephone communication with each patient. Statistical analysis showed that no significant difference was noticed in the long-term QOL of patients with tongue cancer after tongue reconstruction using LUFF or RFFF, respectively, indicating that similar QOLs were obtained in the long-term follow-up of patients with tongue cancer (T2 or T3 stages) using LUFF and RFFF for reconstruction.

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