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1.
Anaesthesiologie ; 73(5): 324-335, 2024 May.
Artigo em Alemão | MEDLINE | ID: mdl-38691128

RESUMO

BACKGROUND: The utilization of AI language models in education and academia is currently a subject of research, and applications in clinical settings are also being tested. Studies conducted by various research groups have demonstrated that language models can answer questions related to medical board examinations, and there are potential applications of these models in medical education as well. RESEARCH QUESTION: This study aims to investigate the extent to which current version language models prove effective for addressing medical inquiries, their potential utility in medical education, and the challenges that still exist in the functioning of AI language models. METHOD: The program ChatGPT, based on GPT 3.5, had to answer 1025 questions from the second part (M2) of the medical board examination. The study examined whether any errors and what types of errors occurred. Additionally, the language model was asked to generate essays on the learning objectives outlined in the standard curriculum for specialist training in anesthesiology and the supplementary qualification in emergency medicine. These essays were analyzed afterwards and checked for errors and anomalies. RESULTS: The findings indicated that ChatGPT was able to correctly answer the questions with an accuracy rate exceeding 69%, even when the questions included references to visual aids. This represented an improvement in the accuracy of answering board examination questions compared to a study conducted in March; however, when it came to generating essays a high error rate was observed. DISCUSSION: Considering the current pace of ongoing improvements in AI language models, widespread clinical implementation, especially in emergency departments as well as emergency and intensive care medicine with the assistance of medical trainees, is a plausible scenario. These models can provide insights to support medical professionals in their work, without relying solely on the language model. Although the use of these models in education holds promise, it currently requires a significant amount of supervision. Due to hallucinations caused by inadequate training environments for the language model, the generated texts might deviate from the current state of scientific knowledge. Direct deployment in patient care settings without permanent physician supervision does not yet appear to be achievable at present.


Assuntos
Anestesiologia , Inteligência Artificial , Medicina de Emergência , Anestesiologia/educação , Medicina de Emergência/educação , Humanos , Idioma , Currículo , Educação Médica/métodos
2.
Toxicol Lett ; 268: 58-62, 2017 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-28122263

RESUMO

In healthy organisms the metabolism of the trace element zinc is well balanced. If this balance becomes destroyed the free zinc level might increase and cause toxic effects. The present study demonstrates that under definite conditions zinc ions are able to inhibit the ATPase activity of neuron-specific KIF5A (kinesin-1). Correspondingly, the motility activity of KIF5A also decreased. The inhibition rates have been found to depend on the magnesium ion concentration. Lowering the magnesium concentration weakens the inhibition. In addition, also decreases of temperature or increasing the ATP concentration result in reduced inhibition. Zinc ion-mediated inhibition of KIF5A activity might be one molecular cause contributing to impaired transport processes within brain and other organs in cases of zinc dyshomeostasis.


Assuntos
Cloretos/toxicidade , Cinesinas/antagonistas & inibidores , Microtúbulos/efeitos dos fármacos , Moduladores de Tubulina/toxicidade , Compostos de Zinco/toxicidade , Trifosfato de Adenosina/metabolismo , Transporte Biológico/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Cinesinas/metabolismo , Cloreto de Magnésio/toxicidade , Microtúbulos/metabolismo , Temperatura
3.
J Med Chem ; 60(2): 749-766, 2017 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-28045256

RESUMO

We report here a series of 27 10-(4-phenylpiperazin-1-yl)methanones derived from tricyclic heterocycles which were screened for effects on tumor cell growth, inhibition of tubulin polymerization, and induction of cell cycle arrest. Several analogues, among them the 10-(4-(3-methoxyphenyl)piperazine-1-carbonyl)-10H-phenoxazine-3-carbonitrile (16o), showed excellent antiproliferative properties, with low nanomolar GI50 values (16o, mean GI50 of 3.3 nM) against a large number (93) of cancer cell lines. Fifteen compounds potently inhibited tubulin polymerization. Analysis of cell cycle by flow cytometry revealed that inhibition of tumor cell growth was related to an induction of G2/M phase cell cycle blockade. Western blotting and molecular docking studies suggested that these compounds bind efficiently to ß-tubulin at the colchicine binding site. Our studies demonstrate the suitability of the phenoxazine and phenothiazine core and also of the phenylpiperazine moiety for the development of novel and potent tubulin polymerization inhibitors.


Assuntos
Antineoplásicos/farmacologia , Oxazinas/farmacologia , Fenotiazinas/farmacologia , Piperazinas/farmacologia , Moduladores de Tubulina/farmacologia , Alquilantes/farmacologia , Antineoplásicos/química , Etilenodiaminas/farmacologia , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Humanos , Células K562 , Simulação de Acoplamento Molecular , Oxazinas/química , Fenotiazinas/química , Piperazinas/química , Polimerização , Relação Quantitativa Estrutura-Atividade , Tubulina (Proteína)/química , Tubulina (Proteína)/metabolismo , Moduladores de Tubulina/química
4.
Curr Protoc Cytom ; 77: 12.43.1-12.43.44, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27367288

RESUMO

High-content analysis (HCA) converts raw light microscopy images to quantitative data through the automated extraction, multiparametric analysis, and classification of the relevant information content. Combined with automated high-throughput image acquisition, HCA applied to the screening of chemicals or RNAi-reagents is termed high-content screening (HCS). Its power in quantifying cell phenotypes makes HCA applicable also to routine microscopy. However, developing effective HCA and bioinformatic analysis pipelines for acquisition of biologically meaningful data in HCS is challenging. Here, the step-by-step development of an HCA assay protocol and an HCS bioinformatics analysis pipeline are described. The protocol's power is demonstrated by application to focal adhesion (FA) detection, quantitative analysis of multiple FA features, and functional annotation of signaling pathways regulating FA size, using primary data of a published RNAi screen. The assay and the underlying strategy are aimed at researchers performing microscopy-based quantitative analysis of subcellular features, on a small scale or in large HCS experiments. © 2016 by John Wiley & Sons, Inc.


Assuntos
Adesões Focais/metabolismo , Ensaios de Triagem em Larga Escala/métodos , Animais , Automação , Células COS , Contagem de Células , Chlorocebus aethiops , Processamento de Imagem Assistida por Computador , Interferência de RNA , Software , Coloração e Rotulagem , Frações Subcelulares/metabolismo
5.
Chem Res Toxicol ; 28(6): 1275-81, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-25871777

RESUMO

It is commonly accepted that aluminum ions may initiate the development of diverse diseases, including neurological disorders. So far, our knowledge of the molecular mechanisms of the interaction of aluminum with defined cellular structures has been still fragmentary. As functional key tasks of neuronal cells essentially depend on the activity of kinesin, we wanted to find out whether this motor protein represents a molecular target for aluminum. We demonstrate that aluminum ions inhibit (IC50 ∼50 µM) the ATPase of the neuron-specific kinesin KIF5A. The ATPase-active center itself, which is located in the kinesin motor domain, does not seem to be directly affected by aluminum. Our results suggest that inhibition is preferentially caused by aluminum binding to some sequence within the kinesin stalk leading to a conformational state of the kinesin molecule, similar to those described in cases of kinesin autoinhibition caused by motor domain-tail binding. Because of the relative high sequence conservation of mammalian kinesin-1 (to which KIF5A belongs), we assume that also in non-neuronal cells the intracellular transport can be affected by aluminum ions.


Assuntos
Alumínio/farmacologia , Cinesinas/antagonistas & inibidores , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Cinesinas/metabolismo , Relação Estrutura-Atividade , Suínos
6.
Arch Toxicol ; 89(4): 565-72, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24853401

RESUMO

Copper is a trace element required to maintain essential life processes. In healthy organisms, copper metabolism is well balanced. If this balance is destroyed, the cellular level of free copper might increase and cause toxic effects. So far, the molecular mechanisms of copper intoxication are understood only partly. The present study revealed that the kinesin-dependent transport system is strongly affected by copper(II) ions. Both the microtubules, along which kinesin moves, and the kinesin itself were found to be the target structures of copper ions: Microtubule formation was suppressed by copper ions (IC50 26-70 µM) apparently chiefly by inhibition of binding of microtubule-associated proteins to tubulin. This inhibition could be widely compensated by the microtubule-stabilising agent paclitaxel. In addition, copper ions strongly inhibited the ATPase activity of neuron-specific kinesin KIF5A. At final KIF5A concentration of 112 nM, an IC50 of 1.3 µM was determined. Correspondingly, the motility activity of KIF5A, measured as velocity of microtubules gliding across a kinesin-covered surface, was blocked. The effects of copper ions on microtubules and on KIF5A are suggested to contribute to impaired transport processes within brain and other organs in cases of copper ion surplus.


Assuntos
Encéfalo/metabolismo , Cobre/química , Cinesinas/química , Microtúbulos/química , Animais , Química Encefálica , Cobre/metabolismo , Eletroforese em Gel de Poliacrilamida , Escherichia coli/genética , Cinesinas/genética , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Paclitaxel/farmacologia , Ligação Proteica , Transporte Proteico , Suínos , Transfecção , Moduladores de Tubulina/farmacologia
7.
PLoS One ; 9(8): e103976, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25133820

RESUMO

Swiprosin-1/EFhd2 (EFhd2) is a cytoskeletal Ca2+ sensor protein strongly expressed in the brain. It has been shown to interact with mutant tau, which can promote neurodegeneration, but nothing is known about the physiological function of EFhd2 in the nervous system. To elucidate this question, we analyzed EFhd2-/-/lacZ reporter mice and showed that lacZ was strongly expressed in the cortex, the dentate gyrus, the CA1 and CA2 regions of the hippocampus, the thalamus, and the olfactory bulb. Immunohistochemistry and western blotting confirmed this pattern and revealed expression of EFhd2 during neuronal maturation. In cortical neurons, EFhd2 was detected in neurites marked by MAP2 and co-localized with pre- and post-synaptic markers. Approximately one third of EFhd2 associated with a biochemically isolated synaptosome preparation. There, EFhd2 was mostly confined to the cytosolic and plasma membrane fractions. Both synaptic endocytosis and exocytosis in primary hippocampal EFhd2-/- neurons were unaltered but transport of synaptophysin-GFP containing vesicles was enhanced in EFhd2-/- primary hippocampal neurons, and notably, EFhd2 inhibited kinesin mediated microtubule gliding. Therefore, we found that EFhd2 is a neuronal protein that interferes with kinesin-mediated transport.


Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Cinesinas/metabolismo , Neuritos/metabolismo , Animais , Transporte Axonal , Células Cultivadas , Hipocampo/citologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transporte Proteico , Sinaptossomos/metabolismo
8.
Toxicol Lett ; 224(3): 356-61, 2014 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-24239783

RESUMO

The anterograde vesicle transport within neurons critically depends on microtubules and on the activity of kinesin. The present study demonstrates that cadmium ions inhibit the in vitro assembly of microtubules from tubulin, whereby at high cadmium levels (∼500 µM) unstructured protein aggregates were formed. Cadmium ions also significantly lower both the ATPase and motility activity of neuron-specific kinesin KIF5A in concentration-dependent manner. For the inhibition of KIF5A ATPase activity, an IC50 value of 10.4±1.5 µM was determined. Inhibition could be widely compensated by addition of EGTA, but not by addition of thiols. The inhibitory effect of cadmium on KIF5A was considerably weakened by increasing ATP concentration. As nucleoside triphosphate binding is known to be accompanied by conformational changes within the kinesin motor domain, it might be suggested that these changes protect the motor domain against cadmium. The effects of cadmium ions on the kinesin-microtubule motility generating system are considered to contribute to the development of neuronal disorders caused by cadmium intoxication.


Assuntos
Cloreto de Cádmio/toxicidade , Cinesinas/fisiologia , Adenosina Trifosfatases/metabolismo , Animais , Transporte Axonal/efeitos dos fármacos , Intoxicação por Cádmio/patologia , Movimento Celular/efeitos dos fármacos , Sistema Livre de Células , Humanos , Cinesinas/metabolismo , Microtúbulos/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Compostos de Sulfidrila/farmacologia , Suínos , Tubulina (Proteína)/metabolismo
9.
Mol Cancer Ther ; 12(11): 2425-35, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23939374

RESUMO

The human androgen receptor plays a major role in the development and progression of prostate cancer and represents a well-established drug target. All clinically approved androgen receptor antagonists possess similar chemical structures and exhibit the same mode of action on the androgen receptor. Although initially effective, resistance to these androgen receptor antagonists usually develops and the cancer quickly progresses to castration-resistant and metastatic states. Yet even in these late-stage patients, the androgen receptor is critical for the progression of the disease. Thus, there is a continuing need for novel chemical classes of androgen receptor antagonists that could help overcome the problem of resistance. In this study, we implemented and used the synergetic combination of virtual and experimental screening to discover a number of new 10-benzylidene-10H-anthracen-9-ones that not only effectively inhibit androgen receptor transcriptional activity, but also induce almost complete degradation of the androgen receptor. Of these 10-benzylidene-10H-anthracen-9-one analogues, a lead compound (VPC-3033) was identified that showed strong androgen displacement potency, effectively inhibited androgen receptor transcriptional activity, and possesses a profound ability to cause degradation of androgen receptor. Notably, VPC-3033 exhibited significant activity against prostate cancer cells that have already developed resistance to the second-generation antiandrogen enzalutamide (formerly known as MDV3100). VPC-3033 also showed strong antiandrogen receptor activity in the LNCaP in vivo xenograft model. These results provide a foundation for the development of a new class of androgen receptor antagonists that can help address the problem of antiandrogen resistance in prostate cancer.


Assuntos
Antagonistas de Receptores de Andrógenos/química , Antagonistas de Receptores de Andrógenos/farmacologia , Antracenos/química , Antracenos/farmacologia , Compostos de Benzilideno/química , Compostos de Benzilideno/farmacologia , Neoplasias de Próstata Resistentes à Castração/metabolismo , Receptores Androgênicos/metabolismo , Antagonistas de Receptores de Andrógenos/metabolismo , Antagonistas de Receptores de Andrógenos/uso terapêutico , Animais , Antracenos/metabolismo , Antracenos/uso terapêutico , Benzamidas , Compostos de Benzilideno/metabolismo , Compostos de Benzilideno/uso terapêutico , Sítios de Ligação/efeitos dos fármacos , Linhagem Celular Tumoral , Bases de Dados Factuais , Modelos Animais de Doenças , Células HeLa , Humanos , Masculino , Camundongos Nus , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Nitrilas , Feniltioidantoína/análogos & derivados , Feniltioidantoína/uso terapêutico , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/genética , Receptores Androgênicos/genética , Ensaios Antitumorais Modelo de Xenoenxerto
10.
J Biol Chem ; 288(30): 21742-54, 2013 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-23744071

RESUMO

Early α-synuclein (α-Syn)-induced alterations are neurite pathologies resulting in Lewy neurites. α-Syn oligomers are a toxic species in synucleinopathies and are suspected to cause neuritic pathology. To investigate how α-Syn oligomers may be linked to aberrant neurite pathology, we modeled different stages of α-Syn aggregation in vitro and investigated the interplay of α-Syn aggregates with proteins involved in axonal transport. The interaction of wild type α-Syn (WTS) and α-Syn variants (E57K, A30P, and aSyn(30-110)) with kinesin, tubulin, and the microtubule (MT)-associated proteins, MAP2 and Tau, is stronger for multimers than for monomers. WTS seeds but not α-Syn oligomers significantly and dose-dependently reduced Tau-promoted MT assembly in vitro. In contrast, MT gliding velocity across kinesin-coated surfaces was significantly decreased in the presence of α-Syn oligomers but not WTS seeds or fibrils (aSyn(30-110) multimers). In a human dopaminergic neuronal cell line, mild overexpression of the oligomerizing E57K α-Syn variant significantly impaired neurite network morphology without causing profound cell death. In accordance with these findings, MT stability, neuritic kinesin, and neuritic kinesin-dependent cargoes were significantly reduced by the presence of α-Syn oligomers. In summary, different α-Syn species act divergently on the axonal transport machinery. These findings provide new insights into α-Syn oligomer-driven neuritic pathology as one of the earliest events in synucleinopathies.


Assuntos
Neurônios Dopaminérgicos/metabolismo , Cinesinas/metabolismo , Microtúbulos/metabolismo , alfa-Sinucleína/metabolismo , Linhagem Celular , Sobrevivência Celular/genética , Proteínas do Citoesqueleto/metabolismo , Neurônios Dopaminérgicos/patologia , Eletroforese em Gel de Poliacrilamida , Humanos , Microscopia de Fluorescência , Proteínas Associadas aos Microtúbulos/metabolismo , Mutação , Neuritos/metabolismo , Neuritos/patologia , Ligação Proteica , Multimerização Proteica , Tubulina (Proteína)/metabolismo , alfa-Sinucleína/química , alfa-Sinucleína/genética , Proteínas tau/metabolismo
11.
Bioorg Med Chem ; 19(14): 4183-91, 2011 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-21705223

RESUMO

A novel series of phenylimino-10H-anthracen-9-ones and 9-(phenylhydrazone)-9,10-anthracenediones were synthesized and evaluated for interaction with tubulin and for cytotoxicity against a panel of human tumor cell lines. The 10-(3-hydroxy-4-methoxy-phenylimino)-10H-anthracen-9-one 15h and its dichloro analog 16b were identified as potent inhibitors of tumor cell growth (16b, IC(50) K562 0.11 µM), including multidrug resistant phenotypes. Compound 15h had excellent activity as an inhibitor of tubulin polymerization. Concentration-dependent cell cycle analyzes by flow cytometry confirmed that KB/HeLa cells treated by 15h and 16b were arrested in the G2/M phases of the cell cycle. In competition experiments, 15h strongly displaced radiolabeled colchicine from its binding site on tubulin, showing IC(50) values similar to that of colchicine. The results obtained demonstrate that the antiproliferative activity is related to the inhibition of tubulin polymerization.


Assuntos
Antracenos/farmacologia , Antineoplásicos/farmacologia , Microtúbulos/efeitos dos fármacos , Bases de Schiff/farmacologia , Tubulina (Proteína)/metabolismo , Antracenos/síntese química , Antracenos/química , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Estrutura Molecular , Bases de Schiff/síntese química , Bases de Schiff/química , Estereoisomerismo , Relação Estrutura-Atividade
12.
J Med Chem ; 54(12): 4247-63, 2011 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-21563750

RESUMO

A total of 53 N-benzoylated phenoxazines and phenothiazines, including their S-oxidized analogues, were synthesized and evaluated for antiproliferative activity, interaction with tubulin, and cell cycle effects. Potent inhibitors of multiple cancer cell lines emerged with the 10-(4-methoxybenzoyl)-10H-phenoxazine-3-carbonitrile (33b, IC(50) values in the range of 2-15 nM) and the isovanillic analogue 33c. Seventeen compounds strongly inhibited tubulin polymerization with activities higher than or comparable to those of the reference compounds such as colchicine. Concentration-dependent flow cytometric studies revealed that inhibition of K562 cell growth was associated with an arrest in the G2/M phases of the cell cycle, indicative of mitotic blockade. Structure-activity relationship studies showed that best potencies were obtained with agents bearing a methoxy group placed para at the terminal phenyl ring and a 3-cyano group in the phenoxazine. A series of analogues highlight not only the phenoxazine but also the phenothiazine structural scaffold as valuable pharmacophores for potent tubulin polymerization inhibitors, worthy of further investigation.


Assuntos
Antineoplásicos/síntese química , Oxazinas/síntese química , Fenotiazinas/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Biopolímeros , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Especificidade de Órgãos , Oxazinas/química , Oxazinas/farmacologia , Fenotiazinas/química , Fenotiazinas/farmacologia , Relação Estrutura-Atividade , Tubulina (Proteína)/química , Moduladores de Tubulina/síntese química , Moduladores de Tubulina/química , Moduladores de Tubulina/farmacologia
13.
Eur J Med Chem ; 45(8): 3420-38, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20537765

RESUMO

A novel series of 1,5- and 1,8-disubstituted 10-benzylidene-10H-anthracen-9-ones and 10-(2-oxo-2-phenylethylidene)-10H-anthracen-9-ones was synthesized to assess the substituent effects on biological activity. The 3-hydroxy-2,4-dimethoxy-benzylidene analogue 16 h displayed strong antiproliferative activity against several tumor cell lines, including multi-drug resistant phenotypes. Flow cytometric studies showed that KB/HeLa cells treated by elected compounds were arrested in the G2/M phases of the cell cycle. Among the compounds tested for inhibition of tubulin polymerization, 14 compounds proved to be exceptionally active with IC(50) values < 1 microM. In the 1,5-dichloro-derived series of benzylideneanthracenones, E/Z isomers were separated and biological effects were monitored. We found that the olefinic geometry had no significant effect on biological activity. Furthermore, the E isomeric 1,5-dichloro-substituted phenacylidenes entirely proved to be more potent inhibitors of tubulin polymerization than the recently described 10-(2-oxo-2-phenylethylidene)-10H-anthracen-9-ones. In conclusion, the present study improves understanding of the action of anthracenone-based tubulin polymerization inhibitors and contributes to the design of further potent anti-tubulin drugs.


Assuntos
Antracenos/química , Antracenos/farmacologia , Compostos de Benzilideno/química , Multimerização Proteica/efeitos dos fármacos , Tubulina (Proteína)/química , Tubulina (Proteína)/metabolismo , Antracenos/síntese química , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Estrutura Quaternária de Proteína
14.
Eur J Med Chem ; 45(8): 3354-64, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20546980

RESUMO

A series of anthracenone-based oxime ethers and -esters were synthesized in order to evaluate their antiproliferative activity. Several investigated compounds displayed strong antiproliferative activity against K562 leukemia cells and proved to be strong inhibitors of tubulin polymerization. In this context, anthracenone-based oxime ethers and -esters are considered to contribute to the development of novel antiproliferative drugs, based on tubulin interaction.


Assuntos
Antracenos/química , Oximas/química , Oximas/farmacologia , Multimerização Proteica/efeitos dos fármacos , Tubulina (Proteína)/química , Tubulina (Proteína)/metabolismo , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Células K562 , Oximas/síntese química , Estrutura Quaternária de Proteína
15.
J Org Chem ; 75(11): 3867-70, 2010 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-20459073

RESUMO

The first synthesis of 2,6-aceanthrylenedione (6), a cyclic vinylog of anthraquinone and a useful starting material for the synthesis of 1-phenylaceanthrylene-2,6-diones such as 7, 8, and 9, is described. (10-Oxo-10H-anthracen-9-ylidene) acetyl chloride (5) cyclizes intramolecularly at room temperature in the presence of AlCl(3) to give 6. We found that 6 is a cytotoxic compound that inhibits tubulin polymerization.


Assuntos
Antracenos/química , Antraquinonas/síntese química , Ciclização , Moduladores de Tubulina
16.
Biochem Biophys Res Commun ; 395(4): 490-5, 2010 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-20399751

RESUMO

During movement along microtubules, kinesin usually follows a track parallel to the axis of a single protofilament. The question arises what happens when kinesin encounters blockages. The present study describes the movement of kinesin labeled by 20-nm gold beads along immobilized microtubules artificially decorated with blocking proteins. To guarantee that exactly the kinesin-binding sites were occupied and to avoid steric effects exerted by large molecules, the KIF5A motor domain was used for blocking. After binding, the blockages were irreversibly cross-linked to the microtubules to make them non-exchangeable. Under such conditions, kinesin movement became a non-continuous one. As a rule, after temporary stopping the kinesin moved on without being released from the microtubule. The results strongly suggest a bypassing mechanism based on the postulation that kinesin changes to and continues movement along a neighbouring protofilament. Bypassing is considered to ensure an efficient long-distance transport of cellular cargoes by kinesins.


Assuntos
Citoesqueleto de Actina/metabolismo , Cinesinas/metabolismo , Microtúbulos/metabolismo , Animais , Humanos , Transporte Proteico , Proteínas Recombinantes/metabolismo
17.
Anal Biochem ; 397(1): 67-72, 2010 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-19825359

RESUMO

Microtubules represent cytoplasmic structures that are indispensable for the maintenance of cell morphology and motility generation. Due to their regular structural organization, microtubules have become of great interest for preparation of in vitro nanotransport systems. However, tubulin, the major building protein of microtubules, is a thermolabile protein and is usually stored at -80 degrees C to preserve its conformation and polymerization properties. Here we describe a novel method for freeze-drying of assembly-competent tubulin in the presence of a nonreducing sugar trehalose. Even after prolonged storage at ambient temperature, rehydrated tubulin is capable of binding antimitotic drugs and assembling to microtubules that bind microtubule-associated proteins in the usual way. Electron microscopy confirmed that rehydrated tubulin assembles into normal microtubules that are able to generate motility by interaction with the motor protein kinesin in a cell-free environment. Freeze-drying also preserved preformed microtubules. Rehydrated tubulin and microtubules can be used for preparation of diverse in vitro and in vivo assays as well as for preparation of bionanodevices.


Assuntos
Liofilização/métodos , Trealose/química , Tubulina (Proteína)/metabolismo , Colchicina/química , Colchicina/metabolismo , Cinesinas/metabolismo , Microtúbulos/química , Microtúbulos/metabolismo , Estabilidade Proteica , Temperatura , Tubulina (Proteína)/química , Tubulina (Proteína)/ultraestrutura
18.
J Nanosci Nanotechnol ; 9(12): 6858-65, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19908690

RESUMO

Co-factors control the GTP-induced assembly of tubulin protein into a variety of superstructures with defined geometry at the nanometre scale: microtubules, macrotubes, sheets, or spirals/rings. We report the Zn2+ ion-induced assembly of tubulin protein into sheet-like or tubular structures. Free functional groups of amino acids on the surface of the protein biopolymer provide nucleation sites for further deposition of small metal nanoparticles. This study describes the synthesis of metal particle--protein hybrids by a two-step chemical process that directs metal nanoparticle nucleation at specific surface sites by applying these tubulin assemblies as biotemplates. The hybrids are characterized by transmission electron microscopy (TEM) and scanning force microscopy (SFM). The present study demonstrates the potential and general applicability of tubulin assemblies as tools for the nanofabrication of nanoparticle arrays exhibiting various geometries.


Assuntos
Cristalização/métodos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Paládio/química , Tubulina (Proteína)/química , Tubulina (Proteína)/ultraestrutura , Zinco/química , Temperatura Alta , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Nanotecnologia/métodos , Tamanho da Partícula , Propriedades de Superfície
19.
J Med Chem ; 52(5): 1284-94, 2009 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-19220018

RESUMO

A series of 10-(2-oxo-2-phenylethylidene)-10H-anthracen-9-ones were synthesized and evaluated for interactions with tubulin and for antiproliferative activity against a panel of human and rodent tumor cell lines. The 4-methoxy analogue 17b was most potent, displaying IC(50) values ranging from 40 to 80 nM, including multidrug resistant phenotypes, and had excellent activity as an inhibitor of tubulin polymerization (IC(50) = 0.52 microM). Concentration-dependent flow cytometric studies showed that KB/HeLa cells treated with 17b were arrested in the G2/M phases of the cell cycle (EC(50) = 90 nM). In competition experiments, 17b strongly displaced [(3)H]-colchicine from its binding site in the tubulin. The results obtained demonstrate that the antiproliferative activity is related to the inhibition of tubulin polymerization.


Assuntos
Antracenos/síntese química , Moduladores de Tubulina/síntese química , Antracenos/química , Antracenos/farmacologia , Ligação Competitiva , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Colchicina/metabolismo , Resistência a Múltiplos Medicamentos , Resistencia a Medicamentos Antineoplásicos , Ensaios de Seleção de Medicamentos Antitumorais , Fase G2/efeitos dos fármacos , Humanos , Ligação Proteica , Relação Estrutura-Atividade , Tubulina (Proteína)/metabolismo , Moduladores de Tubulina/química , Moduladores de Tubulina/farmacologia
20.
J Mol Biol ; 382(1): 127-35, 2008 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-18640125

RESUMO

Despite the high level of similarity in structural organisation of their motor domains and, consequently, in the mechanism of motility generation, kinesin-5 moves about 25-fold slower than conventional kinesin (kinesin-1). To elucidate the structural motifs contributing to velocity regulation, we expressed a set of Eg5- and KIF5A-based chimeric proteins with interchanged native neck linker and neck elements. Among them, the chimera consisting of the Eg5 catalytic core (residues 1-357) fused to the KIF5A linker and neck (residues 326-450) displayed increased velocity compared to the Eg5 control protein. This is the first evidence that the velocity of the slow-moving motor Eg5 can be elevated by insertion of neck linker and neck elements taken from a fast-moving motor. Whereas the complementary chimera composed of the KIF5A core (1-325) and the Eg5 linker and neck (358-513) was found to be immotile, insertion of the first half-KIF5A linker into this chimera restored motility. Our results indicate that the neck linker and the neck are involved not only in motility generation in general and in determination of movement direction, but also in velocity regulation.


Assuntos
Cinesinas/química , Cinesinas/metabolismo , Adenosina Trifosfatases/metabolismo , Transporte Biológico , Fenômenos Biomecânicos , Cristalografia por Raios X , Humanos , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes/metabolismo
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