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1.
J Clin Med ; 12(10)2023 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-37240494

RESUMO

OBJECTIVE: Little research has evaluated trends in psychotropic prescribing and polypharmacy in primary care patients, especially those with dementia. We sought to examine this in Australia from 2011 to 2020 using the primary care dataset, MedicineInsight. METHODS: Ten consecutive serial cross-sectional analyses were performed to evaluate the proportion of patients aged 65 years or more, with a recorded diagnosis of dementia, who were prescribed psychotropic medications within the first six months of each year from 2011 to 2020. This proportion was compared with propensity score-matched control patients without dementia. RESULTS: Before matching, 24,701 patients (59.2% females) with, and 72,105 patients (59.2% females) without, a recorded diagnosis of dementia were included. In 2011, 42% (95% confidence interval [CI] 40.5-43.5%) of patients in the dementia group had at least one recorded prescription of a psychotropic medication, which declined to 34.2% (95% CI 33.3-35.1%; p for trend < 0.001) by 2020. However, it remained unchanged for matched controls (36% [95% CI 34.6-37.5%] in 2011 and 36.7% [95% CI 35.7-37.6%] in 2020). The greatest decline in the dementia groups by medication class was for antipsychotics (from 15.9% [95% CI 14.8-17.0%] to 8.8% [95% CI 8.2-9.4%]; p for trend < 0.001). During this period, the prevalence of psychotropic polypharmacy (use of two or more individual psychotropics) also decreased from 21.7% (95% CI 20.5-22.9%) to 18.1% (95% CI 17.4-18.9%) in the dementia groups, and slightly increased from 15.2% (95% CI 14.1-16.3%) to 16.6% (95% CI 15.9-17.3%) in the matched controls. CONCLUSIONS: The decline in psychotropic prescribing, particularly antipsychotics, in Australian primary care patients with dementia is encouraging. However, psychotropic polypharmacy still occurred in almost one in five patients with dementia at the end of the study period. Programs focused on encouraging further reductions in the use of multiple psychotropic drugs in patients with dementia are recommended, particularly in rural and remote regions.

2.
Methods Mol Biol ; 2587: 427-453, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36401042

RESUMO

The CRISPR-Cas9 system has quickly become the standard tool for genome editing. To deliver this system to target cells, adeno-associated virus (AAV) vectors are commonly used. In fact, AAV vectors have been utilized to deliver the CRISPR-Cas9 system to induce genomic exon skipping and restore the dystrophin protein in various Duchenne muscular dystrophy model animals. Despite the high transduction efficiency, AAV vector-mediated delivery has several limitations, such as the packaging size, prolonged overexpression of Cas9, immunogenicity against the AAV capsid, and the risk of integrating a part of the AAV genomic sequence into the host cell. To overcome these issues, we have recently engineered a transient delivery system utilizing VSV-G pseudotyped extracellular vesicles (EVs) termed NanoMEDIC (nanomembrane-derived extracellular vesicles for the delivery of macromolecular cargo). NanoMEDIC utilizes an HIV-derived Gag protein to package Cas9 protein and gRNA into EVs. The Cas9 and Gag proteins are fused to a heterodimerizer and conditionally dimerized by the addition of an inducible chemical ligand to recruit Cas9 protein into EVs. sgRNA is packaged into EVs through an HIV-derived RNA packaging signal and is subsequently released by two self-cleaving ribozymes. Utilizing these features, NanoMEDIC can achieve highly efficient packaging of the Cas9 protein and gRNA for genome editing into a variety of target cells and in vivo. Here, we describe a step-by-step protocol, including the gRNA-expressing vector construction and large-scale NanoMEDIC production, for in vivo genome editing.


Assuntos
Vesículas Extracelulares , Infecções por HIV , Animais , Proteína 9 Associada à CRISPR/genética , Sistemas CRISPR-Cas/genética , Éxons/genética , Vesículas Extracelulares/genética , Genômica , Infecções por HIV/genética , Ribonucleoproteínas/genética , RNA Guia de Sistemas CRISPR-Cas/genética
3.
JMIR Serious Games ; 8(4): e23734, 2020 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-33315016

RESUMO

BACKGROUND: Numerous mobile health (mHealth) apps have been developed to support smokers attempting to quit smoking. Although these apps have been reported to be successful, only modest improvements in the quit rate have been measured. It has been proposed that efforts to improve user engagement and retention may improve the quit rate further. Owing to the high cost of smoking-related disease, it is considered worthwhile to pursue even small improvements. OBJECTIVE: The aim of this study was to test a novel smartphone app that leverages premium currency strategies developed by the mobile games industry in an attempt to improve engagement and retention with a smoking cessation intervention. METHODS: We designed and developed a smoking cessation app called "Quittr" in line with previously developed smoking cessation mHealth apps. In addition to this established framework, we added a stand-alone fully featured city-building clicker-style game called "Tappy Town," and a premium virtual currency called "QuitCoins." The user earns QuitCoins for using the app in a way that contributes positively toward their quit attempt, and they can redeem these coins in Tappy Town for bonuses. To establish whether these features improved engagement and retention, we ran a 5-month randomized controlled trial where the intervention group had the full app with the extra games features, while the control group had the standard app only. Recruitment was performed via web-based advertising. Participants (N=175) had no direct contact with the researchers or other support staff. RESULTS: No significant differences in terms of engagement, retention, or smoking outcomes were found between the control and intervention groups. However, survey data indicated that the majority of the participants valued Tappy Town (10/17, 59%) and the QuitCoins rewards system (13/17, 77%). Usage data also suggested that Tappy Town was widely played and was generally appealing to users (mean total time spent in app, control group: 797 seconds vs intervention group: 3502 seconds, P<.001). Analysis of the results suggests that users in the intervention group may have been negatively affected by the aspects of the chosen design, and some theories were explored to explain this unexpected outcome. CONCLUSIONS: Although the novel features of the Quittr app failed to improve the key outcomes measured in this study, there were enough positive indications to warrant further exploration of the concept. Additional research will be required to identify and correct any design flaws that may have adversely affected our participants before a follow-up study can be completed. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Register ACTRN12617000491369; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=372661&isReview=true.

4.
Biochem Biophys Res Commun ; 505(4): 1097-1102, 2018 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-30316514

RESUMO

The delivery of mRNA is advantageous over DNA delivery as it is transient and does not carry the risk of genomic DNA integration. However, there are currently few efficient mRNA delivery options available, especially for hard-to-transfect cell types, and thus new delivery methods are needed. To this end, we have established a novel mRNA delivery system utilizing chimeric virus-like particles (VLPs). We generated a novel VLP by fusing protein G of Vesicular stomatitis virus (VSV-G) with a ribosomal protein L7Ae of Archeoglobus fulgidus. This system allowed the efficient delivery of EGFP mRNA which was independent from the presence of BoxC/D motif in the mRNA sequence. Our VSVG-L7Ae VLP system demonstrated high transduction efficacy in hard-to-transfect cell lines, such as human induced pluripotent stem cells (iPS cells) and monocytes. In summary, this platform may serve as an efficient and transient transgene delivery tool for an mRNA of interest.


Assuntos
Técnicas de Transferência de Genes , Glicoproteínas de Membrana/química , RNA Mensageiro/genética , Proteínas Ribossômicas/química , Proteínas do Envelope Viral/química , Células HEK293 , Humanos
5.
Support Care Cancer ; 26(9): 3233-3239, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29627861

RESUMO

INTRODUCTION: The previously reported Patients' Experience of LIving with CANcer-associated thrombosis (PELICAN) identified several areas of unmet clinical and support need for cancer patients diagnosed with venous thromboembolism (VTE) in the UK. It is not known whether such experiences are restricted to one particular country's healthcare system and culture. We therefore undertook an evaluation of patients' experience of cancer-associated thrombosis (CAT) within a Spanish setting. METHODS: Twenty consecutive Spanish patients with CAT were interviewed about their experiences of living with CAT as per the previous PELICAN study. Where possible, spouses were interviewed in conjunction. Semi-structured interviews were audio recorded, transcribed and translated into English. Transcripts were coded using Nvivo software and data were analysed using framework analysis. A pragmatic approach was undertaken to allow explication of the potential cultural and operational differences that were not apparent in the UK dataset. RESULTS: Several commonalities between the UK and Spanish patients were identified including the traumatic nature of the experience, the need for information and adaptive behaviors through ritualisation. Within the major themes lay new themes as follows. (1) The traumatic experience of CAT impacted on the family dynamic with respect to discussions within the family unit and support needs of individuals other than the patient. It also had a profound impact on the patient's concept of self with increased awareness of their mortality and seriousness of the cancer. (2) The need for information extended to the family as well as the patients. This was needed at the point of CAT diagnosis as well as an opportunity to later address unanswered questions. (3) Adaptive behaviors were common with similar ritualisations seen in the UK patients. CONCLUSION: The distress experienced by patients with CAT is not isolated to the UK alone but is similar in Spanish patients as well. The patient information provided regarding LMWH injections is important, but there is a need to for patients and their families to be given additional information about CAT itself and future prognosis. CAT also has a profound impact on the patient's family who has similar support needs. It appears that there are several commonalities between UK and Spanish patients, as well as specific local issues. This study justifies expansion of the sampling to other countries.


Assuntos
Coleta de Dados/métodos , Neoplasias/complicações , Trombose/etiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/patologia , Espanha , Trombose/patologia
6.
JMIR Serious Games ; 4(2): e19, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-27908844

RESUMO

BACKGROUND: Smoking is recognized as the largest, single, preventable cause of death and disease in the developed world. While the majority of smokers report wanting to quit, and many try each year, smokers find it difficult to maintain long-term abstinence. Behavioral support, such as education, advice, goal-setting, and encouragement, is known to be beneficial in improving the likelihood of succeeding in a quit attempt, but it remains difficult to effectively deliver this behavioral support and keep the patient engaged with the process for a sufficient duration. In an attempt to solve this, there have been numerous mobile apps developed, yet engagement and retention have remained key challenges that limit the potential effectiveness of these interventions. Video games have been clearly linked with the effective delivery of health interventions, due to their capacity to increase motivation and engagement of players. OBJECTIVE: The objective of this study is to describe the design and development of a smartphone app that is theory-driven, and which incorporates gaming characteristics in order to promote engagement with content, and thereby help smokers to quit. METHODS: Game design and development was informed by a taxonomy of motivational affordances for meaningful gamified and persuasive technologies. This taxonomy describes a set of design components that is grounded in well-established psychological theories on motivation. RESULTS: This paper reports on the design and development process of Quittr, a mobile app, describing how game design principles, game mechanics, and game elements can be used to embed education and support content, such that the app actually requires the user to access and engage with relevant educational content. The next stage of this research is to conduct a randomized controlled trial to determine whether the additional incentivization game features offer any value in terms of the key metrics of engagement-how much content users are consuming, how many days users are persisting with using the app, and what proportion of users successfully abstain from smoking for 28 days, based on user-reported data and verified against a biochemical baseline using cotinine tests. CONCLUSIONS: We describe a novel, and theoretically-informed mobile app design approach that has a broad range of potential applications. By using the virtual currency approach, we remove the need for the game to comprehensively integrate the healthy activity as part of its actual play mechanics. This opens up the potential for a wide variety of health problems to be tackled through games where no obvious play mechanic presents itself. The implications of this app are that similar approaches may be of benefit in areas such as managing chronic conditions (diabetes, heart disease, etc), treating substance abuse (alcohol, illicit drugs, etc), diet and exercise, eating disorders (anorexia, bulimia, and binge eating), and various phobias.

7.
Int J Mol Sci ; 16(10): 24751-71, 2015 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-26501275

RESUMO

Programmable nucleases, such as zinc finger nucleases (ZFNs), transcription activator like effector nucleases (TALENs), and clustered regularly interspersed short palindromic repeats associated protein-9 (CRISPR-Cas9), hold tremendous potential for applications in the clinical setting to treat genetic diseases or prevent infectious diseases. However, because the accuracy of DNA recognition by these nucleases is not always perfect, off-target mutagenesis may result in undesirable adverse events in treated patients such as cellular toxicity or tumorigenesis. Therefore, designing nucleases and analyzing their activity must be carefully evaluated to minimize off-target mutagenesis. Furthermore, rigorous genomic testing will be important to ensure the integrity of nuclease modified cells. In this review, we provide an overview of available nuclease designing platforms, nuclease engineering approaches to minimize off-target activity, and methods to evaluate both on- and off-target cleavage of CRISPR-Cas9.


Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Endonucleases/genética , Mutagênese/genética , Animais , Engenharia Genética , Humanos
8.
J Virol ; 85(19): 9726-36, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21775448

RESUMO

APOBEC1 (A1) is a cytidine deaminase involved in the regulation of lipids in the small intestine. Herpes simplex virus 1 (HSV-1) is a ubiquitous pathogen that is capable of infecting neurons in the brain, causing encephalitis. Here, we show that A1 is induced during encephalitis in neurons of rats infected with HSV-1. In cells stably expressing A1, HSV-1 infection resulted in significantly reduced virus replication compared to that in control cells. Infectivity could be restored to levels comparable to those observed for control cells if A1 expression was silenced by specific A1 short hairpin RNAs (shRNA). Moreover, cytidine deaminase activity appeared to be essential for this inhibition and led to an impaired accumulation of viral mRNA transcripts and DNA copy numbers. The sequencing of viral gene UL54 DNA, extracted from infected A1-expressing cells, revealed G-to-A and C-to-T transitions, indicating that A1 associates with HSV-1 DNA. Taken together, our results demonstrate a model in which A1 induction during encephalitis in neurons may aid in thwarting HSV-1 infection.


Assuntos
Citidina Desaminase/imunologia , Citidina Desaminase/metabolismo , DNA/metabolismo , Encefalite por Herpes Simples/imunologia , Encefalite por Herpes Simples/virologia , Herpesvirus Humano 1/crescimento & desenvolvimento , Herpesvirus Humano 1/patogenicidade , Desaminase APOBEC-1 , Animais , DNA Viral/metabolismo , Modelos Animais de Doenças , Neurônios/imunologia , Neurônios/virologia , RNA Viral/metabolismo , Ratos , Doenças dos Roedores/imunologia , Doenças dos Roedores/virologia , Análise de Sobrevida , Virulência , Replicação Viral
9.
Antiviral Res ; 87(2): 213-22, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20470829

RESUMO

Dengue virus (DENV), an emerging pathogen from the Flaviviridae family with neither vaccine nor antiviral treatment available, causes a serious worldwide public health threat. In theory, there are several ways by which small molecules could inhibit the replication cycle of DENV. Here, we show that the nucleoside analogue beta-d-2'-ethynyl-7-deaza-adenosine inhibits representative strains of all four serotypes of DENV with an EC(50) around or below 1microM. Using membrane-associated native replicase complex as well as recombinant RNA polymerase from each DENV serotype in enzymatic assays, we provide evidence that beta-d-2'-ethynyl-7-deaza-adenosine triphosphate (2'E-7D-ATP) targets viral replication at the polymerase active site by competing with the natural nucleotide substrate with an apparent K(i) of 0.060+/-0.016microM. In single-nucleotide incorporation experiments, the catalytic efficiency of 2'E-7D-ATP is 10-fold lower than for natural ATP, and the incorporated nucleotide analogue causes immediate chain termination. A combination of bioinformatics and site-directed mutagenesis demonstrates that 2'E-7D-ATP is equipotent across all serotypes because the nucleotide binding site residues are conserved in dengue virus. Overall, beta-d-2'-ethynyl-7-deaza-adenosine provides a promising scaffold for the development of inhibitors of dengue virus polymerase.


Assuntos
Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/farmacologia , Antivirais/farmacologia , RNA Polimerases Dirigidas por DNA/antagonistas & inibidores , Vírus da Dengue/enzimologia , Inibidores Enzimáticos/farmacologia , Animais , Antivirais/química , Sítios de Ligação , Linhagem Celular , Biologia Computacional , Sequência Conservada , Cricetinae , Inibidores Enzimáticos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mutagênese Sítio-Dirigida
10.
J Biol Chem ; 283(14): 9488-96, 2008 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-18268020

RESUMO

Retinoic acid-inducible gene I (RIG-I) is a cytosolic receptor that recognizes viral RNA and activates the interferon-mediated innate antiviral response. To understand the mechanism of signal activation at the receptor level, we cloned, expressed, and purified human RIG-I containing the two caspase activation and recruitment domains (CARDs) followed by the C-terminal helicase domain. We found that recombinant RIG-I is a functional protein that interacts with double-stranded RNA with substantially higher affinity as compared with single-stranded RNA structures unless they contain a 5'-triphosphate group. Viral RNA binding to RIG-I stimulates the velocity of ATP hydrolysis by 33-fold, which at the cellular level translates into a 43-fold increase of interferon-beta expression. In contrast, the isolated ATPase/helicase domain is constitutively activated while also retaining its RNA ligand binding properties. These results support the recent model by which RIG-I signaling is autoinhibited in the absence of RNA by intra-molecular interactions between the CARDs and the C terminus. Based on pH profile and metal ion dependence experiments, we propose that the active site of RIG-I cannot efficiently accommodate divalent cations under the RNA-free repressed conformation. Overall, these results show a direct correlation between RNA binding and ATPase enzymatic function leading to signal transduction and suggest that a tight control of ATPase activity by the CARDs prevents RIG-I signaling in the absence of viral RNA.


Assuntos
Adenosina Trifosfatases/metabolismo , RNA Viral/metabolismo , Proteínas de Ligação a RNA/metabolismo , Receptores do Ácido Retinoico/metabolismo , Transdução de Sinais/fisiologia , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/imunologia , Caspases/genética , Caspases/imunologia , Caspases/metabolismo , Cátions Bivalentes/imunologia , Cátions Bivalentes/metabolismo , Linhagem Celular , Ativação Enzimática/fisiologia , Humanos , Imunidade Inata/fisiologia , Interferon beta/genética , Interferon beta/imunologia , Interferon beta/metabolismo , Metais/imunologia , Metais/metabolismo , Estrutura Terciária de Proteína/fisiologia , RNA Viral/genética , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/imunologia , Receptores do Ácido Retinoico/genética , Receptores do Ácido Retinoico/imunologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/metabolismo , Viroses/enzimologia , Viroses/genética , Viroses/imunologia , Viroses/metabolismo
11.
Proteins ; 63(1): 136-43, 2006 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-16435370

RESUMO

It has been suggested that the stability of a beta-peptide helical fold is affected by the interplay between the electrical charge of terminal groups and the dipole due to the helical conformation, the so-called charge-dipole stabilization; the numerical simulations presented herein test that suggestion. The motions of two beta-peptide oligomers, each of which has been shown by NMR spectroscopy to fold into a different helical conformation, have been simulated. The simulated motions bear out empirical observations as to the effect of chemical protection of terminal groups on the stability of beta-peptide helical folds and they support the hypothesis of charge-dipole stabilization.


Assuntos
Peptídeos/química , Proteômica/métodos , Espectrofotometria/métodos , Simulação por Computador , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Modelos Químicos , Modelos Moleculares , Conformação Molecular , Dados de Sequência Molecular , Oligopeptídeos , Biossíntese Peptídica , Fragmentos de Peptídeos , Conformação Proteica , Desnaturação Proteica , Dobramento de Proteína , Estrutura Secundária de Proteína , Software , Termodinâmica , Fatores de Tempo
12.
J Biol Chem ; 279(35): 37153-62, 2004 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-15210722

RESUMO

Epidermal growth factor receptor (EGFR) controls cell growth and has a key role in tumorigenic processes. The extent of EGFR signaling is tightly regulated by post-transcriptional modifications leading to down-regulation of the levels of the receptor. Previous studies from our laboratory demonstrated that the reactive oxidant hydrogen peroxide activates the EGFR, yet, without down-regulation of the receptor levels, which results in prolonged receptor signaling. In the present study we examined the role of the E3 ligase c-Cbl, as a possible link between oxidative stress, EGFR signaling, and tumorigenic responses. First, we ectopically expressed a mutant EGFR (Tyr-1045 --> Phe) in cells lacking endogenous receptor, to determine whether the lack of phosphorylation at this site is the cause for EGFR retention at the membrane under oxidative stress, as we have previously suggested. Our findings suggest that abrogation of tyrosine 1045 phosphorylation alone is not enough to retain the EGFR at the plasma membrane under oxidative stress. Second, through the use of the Src inhibitor PP1, our findings establish EGFR movement out of the early endosomes as the exact location where c-Cbl-mediated ubiquitinylation is essential for EGFR trafficking. Finally, our studies substantiate the findings that c-Cbl-mediated ubiquitinylation is needed for degradation, but not for internalization of the EGFR in both transfection-dependent Chinese hamster ovary cells and transfection-independent A549 lung epithelial cells. These findings only begin to explain the features seen under oxidative stress, but they yield a greater understanding of the role of c-Cbl in EGFR trafficking.


Assuntos
Endossomos/metabolismo , Receptores ErbB/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Western Blotting , Células CHO , Linhagem Celular Tumoral , Cricetinae , Regulação para Baixo , Humanos , Peróxido de Hidrogênio/química , Microscopia de Fluorescência , Modelos Biológicos , Mutação , Estresse Oxidativo , Fenilalanina/química , Fosfoproteínas Fosfatases/metabolismo , Testes de Precipitina , Transporte Proteico , Proteínas Proto-Oncogênicas c-cbl , Processamento Pós-Transcricional do RNA , Transdução de Sinais , Transfecção , Tirosina/química , Ubiquitina/metabolismo
13.
Am J Physiol Lung Cell Mol Physiol ; 284(6): L1082-92, 2003 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12576296

RESUMO

Ceramide, the basic structural unit of sphingolipids, controls the balance between cell growth and death by inducing apoptosis. We have previously shown that accumulation of ceramide, triggered by hydrogen peroxide (H(2)O(2)) or by short-chain ceramide analogs, induces apoptosis of lung epithelial cells. Here we elucidate the link between caspase-3 activation, at the execution phase, and ceramide accumulation, at the commitment phase of apoptosis in A549 human lung adenocarcinoma cells. The induction of ceramide accumulation by various triggers of ceramide generation, such as H(2)O(2), C(6)-ceramide, or UDP-glucose-ceramide glucosyltransferase inhibitor dl-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, triggered the activation of caspase-3. This ceramide elevation also induced the cleavage of the death substrate poly(ADP-ribose) polymerase and was followed by apoptotic cell death. Ceramide-mediated apoptosis was blocked by a general caspase inhibitor, Boc-d-fluoromethylketone, and by overexpression of the antiapoptotic protein Bcl-2. Notably, overexpression of Bcl-2 reduced the basal cellular levels of ceramide and prevented the induction of ceramide generation by C(6)-ceramide, which implies ceramide generation as a possible target for the antiapoptotic effects of Bcl-2.


Assuntos
Adenocarcinoma , Apoptose/fisiologia , Caspases/metabolismo , Ceramidas/metabolismo , Neoplasias Pulmonares , Apoptose/efeitos dos fármacos , Caspase 3 , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Inibidores Enzimáticos/farmacologia , Expressão Gênica , Humanos , Peróxido de Hidrogênio/farmacologia , Morfolinas/farmacologia , Oxidantes/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/genética , Células Tumorais Cultivadas
15.
J Biol Chem ; 277(34): 31214-9, 2002 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-12063263

RESUMO

Activation of the epidermal growth factor (EGF) receptor by its ligand, EGF, rapidly enhances receptor internalization and degradation, which desensitizes receptor signaling. In contrast, we have shown previously that exposure to oxidative stress in the form of hydrogen peroxide (H(2)O(2)) activated the EGF receptor but that the levels of activated receptors did not decline, which resulted in prolonged receptor signaling. This study provides mechanistic insights into these different modes of EGF receptor activation. Here we demonstrate that the pattern of receptor tyrosine phosphorylation induced by H(2)O(2) differs from that induced by its ligand, EGF. Importantly, H(2)O(2) generates a receptor with negligible phosphorylation at tyrosine 1045, the major docking site for the ubiquitin ligase c-Cbl. As a result, H(2)O(2)-activated receptors fail to recruit c-Cbl and do not undergo ubiquitination and endocytosis. In summary, H(2)O(2) stimulation results in an activated receptor uncoupled from normal down-regulation, a process that may contribute to oxidant-mediated tumorigenesis.


Assuntos
Receptores ErbB/metabolismo , Estresse Oxidativo , Proteínas Proto-Oncogênicas/fisiologia , Ubiquitina-Proteína Ligases , Regulação para Baixo , Fator de Crescimento Epidérmico/farmacologia , Receptores ErbB/análise , Glucose Oxidase/farmacologia , Humanos , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/farmacologia , Fosforilação , Proteínas Proto-Oncogênicas c-cbl , Tirosina/metabolismo , Ubiquitina/metabolismo
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