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1.
NPJ Precis Oncol ; 8(1): 114, 2024 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-38783041

RESUMO

The proto-oncogene MYC encodes a nuclear transcription factor that has an important role in a variety of cellular processes, such as cell cycle progression, proliferation, metabolism, adhesion, apoptosis, and therapeutic resistance. MYC amplification is consistently observed in aggressive forms of several solid malignancies and correlates with poor prognosis and distant metastases. While the tumorigenic effects of MYC in patients with head and neck squamous cell carcinoma (HNSCC) are well known, the molecular mechanisms by which the amplification of this gene may confer treatment resistance, especially to immune checkpoint inhibitors, remains under-investigated. Here we present a unique case of a patient with recurrent/metastatic (R/M) HNSCC who, despite initial response to nivolumab-based treatment, developed rapidly progressive metastatic disease after the acquisition of MYC amplification. We conducted comparative transcriptomic analysis of this patient's tumor at baseline and upon progression to interrogate potential molecular processes through which MYC may confer resistance to immunotherapy and/or chemoradiation and used TCGA-HNSC dataset and an institutional cohort to further explore clinicopathologic features and key molecular networks associated with MYC amplification in HNSCC. This study highlights MYC amplification as a potential mechanism of immune checkpoint inhibitor resistance and suggest its use as a predictive biomarker and potential therapeutic target in R/M HNSCC.

2.
Am Soc Clin Oncol Educ Book ; 44(3): e433330, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38718318

RESUMO

The treatment for recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) with immune checkpoint inhibitors (anti-PD1) with or without chemotherapy has led to an improvement in survival. Yet, despite this therapeutic advancement, only 15%-19% of patients remain alive at four years, highlighting the poor survival and unmet need for improved therapies for this patient population. Some of the key evolving novel therapeutics beyond anti-PD1 in R/M HNSCC have included therapeutic vaccine therapies, bispecific antibodies/fusion proteins and multitargeted kinase inhibitors, and antibody-drug conjugates (ADCs). Multiple concurrent investigations of novel therapeutics for patients with R/M HNSCC beyond anti-PD(L)1 inhibition are currently underway with some promising early results. Beyond immune checkpoint inhibition, novel immunotherapeutic strategies including therapeutic vaccines ranging from targeting human papillomavirus-specific epitopes to personalized neoantigen vaccines are ongoing with some early efficacy signals and large, randomized trials. Other novel weapons including bispecific antibodies, fusion proteins, and multitargeted kinase inhibitors leverage multiple concurrent targets and modulation of the tumor microenvironment to harness antitumor immunity and inhibition of protumorigenic signaling pathways with emerging promising results. Finally, as with other solid tumors, ADCs remain a promising therapeutic intervention either alone or in combination with immunotherapy for patients with R/M HNSCC. With early enthusiasm across novel therapies in R/M HNSCC, results of larger randomized trials in R/M HNSCC are eagerly awaited.


Assuntos
Imunoterapia , Carcinoma de Células Escamosas de Cabeça e Pescoço , Humanos , Carcinoma de Células Escamosas de Cabeça e Pescoço/terapia , Carcinoma de Células Escamosas de Cabeça e Pescoço/imunologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/tratamento farmacológico , Imunoterapia/métodos , Neoplasias de Cabeça e Pescoço/terapia , Neoplasias de Cabeça e Pescoço/imunologia , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Antígeno B7-H1/antagonistas & inibidores , Inibidores de Checkpoint Imunológico/uso terapêutico , Terapia de Alvo Molecular , Metástase Neoplásica , Recidiva Local de Neoplasia , Vacinas Anticâncer/uso terapêutico
3.
Small ; 18(23): e2201982, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35567438

RESUMO

Mixed matrix materials (MMMs) hold great potential for membrane gas separations by merging nanofillers with unique nanostructures and polymers with excellent processability. In situ growth of the nanofillers is adapted to mitigate interfacial incompatibility to avoid the selectivity loss. Surprisingly, functional polymers have not been exploited to co-grow the nanofillers for membrane applications. Herein, in situ synergistic growth of crystalline zeolite imidazole framework-8 (ZIF-8) in polybenzimidazole (PBI), creating highly porous structures with high gas permeability, is demonstrated. More importantly, PBI contains benzimidazole groups (similar to the precursor for ZIF-8, i.e., 2-methylimidazole) and induces the formation of amorphous ZIFs, enhancing interfacial compatibility and creating highly size-discriminating bottlenecks. For instance, the formation of 15 mass% ZIF-8 in PBI improves H2 permeability and H2 /CO2 selectivity by ≈100% at 35 °C, breaking the permeability/selectivity tradeoff. This work unveils a new platform of MMMs comprising functional polymer-incorporated amorphous ZIFs with hierarchical nanostructures for various applications.

4.
Sci Adv ; 8(10): eabl8160, 2022 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-35263122

RESUMO

Carbon molecular sieve (CMS) membranes prepared by carbonization of polymers containing strongly size-sieving ultramicropores are attractive for high-temperature gas separations. However, polymers need to be carbonized at extremely high temperatures (900° to 1200°C) to achieve sub-3.3 Å ultramicroporous channels for H2/CO2 separation, which makes them brittle and impractical for industrial applications. Here, we demonstrate that polymers can be first doped with thermolabile cross-linkers before low-temperature carbonization to retain the polymer processability and achieve superior H2/CO2 separation properties. Specifically, polybenzimidazole (PBI) is cross-linked with pyrophosphoric acid (PPA) via H bonding and proton transfer before carbonization at ≤600°C. The synergistic PPA doping and subsequent carbonization of PBI increase H2 permeability from 27 to 140 Barrer and H2/CO2 selectivity from 15 to 58 at 150°C, superior to state-of-the-art polymeric materials and surpassing Robeson's upper bound. This study provides a facile and effective way to tailor subnanopore size and porosity in CMS membranes with desirable molecular sieving ability.

5.
Br J Cancer ; 122(5): 726-732, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31919405

RESUMO

BACKGROUND: Previous studies suggest a protective role of physical activity in breast cancer risk, largely based on self-reported activity. We aimed to clarify this association by examining breast cancer risk in relation to self-reported physical activity, informed by accelerometer-based measures in a large subset of participants. METHODS: We analysed data from 47,456 premenopausal and 126,704 postmenopausal women in UK Biobank followed from 2006 to 2014. Physical activity was self-reported at baseline, and at resurvey in a subsample of 6443 participants. Accelerometer data, measured from 2013 to 2015, were available in 20,785 women. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated by using multivariable-adjusted Cox regression. RESULTS: A total of 3189 cases were diagnosed during follow-up (mean = 5.7 years). Women in the top compared with the bottom quartile of self-reported physical activity had a reduced risk of both premenopausal (RR 0.75; 95% CI 0.60-0.93) and postmenopausal breast cancer (RR 0.87; 95% CI 0.78-0.98), after adjusting for adiposity. In analyses utilising physical activity values assigned from accelerometer measurements, an increase of 5 milli-gravity was associated with a 21% (RR 0.79; 95% CI 0.66-0.95) reduction in premenopausal and a 16% (RR 0.84; 95% CI 0.73-0.96) reduction in postmenopausal breast cancer risk. CONCLUSIONS: Greater physical activity is associated with a reduction in breast cancer risk, which appears to be independent of any association it may have on risk through its effects on adiposity.


Assuntos
Neoplasias da Mama/epidemiologia , Exercício Físico , Acelerometria , Estudos de Coortes , Feminino , Humanos , Pessoa de Meia-Idade , Pós-Menopausa , Pré-Menopausa , Modelos de Riscos Proporcionais , Estudos Prospectivos , Risco , Autorrelato , Reino Unido/epidemiologia
7.
Am J Clin Nutr ; 110(2): 461-472, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31190054

RESUMO

BACKGROUND: There may be differences in hematological parameters between meat-eaters and vegetarians. OBJECTIVE: The aim of this study was to perform cross-sectional analyses of hematological parameters by diet group in a large cohort in the United Kingdom. METHODS: A complete blood count was carried out in all UK Biobank participants at recruitment (2006-2010). We examined hemoglobin, red and white blood cell counts, and platelet counts and volume in regular meat eaters (>3 times/wk of red/processed meat consumption, n = 212,831), low meat eaters (n = 213,092), poultry eaters (n = 4815), fish eaters (n = 10,042), vegetarians (n = 6548), and vegans (n = 398) of white ethnicity and meat eaters (n = 3875) and vegetarians (n = 1362) of British Indian ethnicity. RESULTS: In both white and British Indian populations, compared with regular meat eaters (or meat eaters in Indians), the other diet groups had up to 3.7% lower age-adjusted hemoglobin concentrations (difference not significant in white vegan women) and were generally more likely to have anemia (e.g., 8.7% of regular meat eaters compared with 12.8% of vegetarians in white premenopausal women; P < 0.05 after Bonferroni correction). In the white population, compared with regular meat eaters, all other diet groups had lower age- and sex-adjusted total white cells, neutrophils, lymphocytes, monocytes, and eosinophils (P-heterogeneity < 0.001 for all), but basophil counts were similar across diet groups; in British Indians, there was no significant difference in any of the white blood cell counts by diet group. Compared with white regular meat eaters, the low meat eaters, poultry eaters, fish eaters, and vegans had significantly lower platelet counts and higher platelet volume, whereas vegetarians had higher counts and lower volume. Compared with British Indian meat eaters, vegetarians had higher platelet count and lower volume. CONCLUSIONS: In the UK Biobank, people with low or no red meat intake generally had lower hemoglobin concentrations and were slightly more likely to be anemic. The lower white blood cell counts observed in low and non-meat eaters, and differences in mean platelet counts and volume between diet groups, warrant further investigation. This observational study was registered at http://www.isrctn.com/ as ISRCTN10125697.


Assuntos
Anemia/epidemiologia , Povo Asiático , Dieta/classificação , Carne , Vegetarianos , População Branca , Anemia/etiologia , Estudos de Coortes , Estudos Transversais , Dieta Vegetariana , Comportamento Alimentar , Humanos , Prevalência , Reino Unido/epidemiologia , Veganos
8.
BMJ Open ; 9(1): e024206, 2019 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-30700478

RESUMO

OBJECTIVES: Previous studies of the association between physical activity and adiposity are largely based on physical activity and body mass index (BMI) from questionnaires, which are prone to inaccurate and biased reporting. We assessed the associations of accelerometer-measured and questionnaire-measured physical activity with BMI, waist circumference and body fat per cent measured by bioelectrical impedance and dual-energy X-ray absorptiometry (DXA). DESIGN: Cross-sectional analysis of UK Biobank participants. SETTING: UK Biobank assessment centres. PARTICIPANTS: 78 947 UK Biobank participants (35 955 men and 42 992 women) aged 40-70 at recruitment, who had physical activity measured by both questionnaire and accelerometer. MAIN OUTCOME MEASURES: BMI, waist circumference and body fat per cent measured by bioelectrical impedance. RESULTS: Greater physical activity was associated with lower adiposity. Women in the top 10th of accelerometer-measured physical activity had a 4.8 (95% CI 4.6 to 5.0) kg/m2 lower BMI, 8.1% (95% CI 7.8% to 8.3%) lower body fat per cent and 11.9 (95% CI 11.4 to 12.4) cm lower waist circumference. Women in the top 10th of questionnaire-measured physical activity had a 2.5 (95% CI 2.3 to 2.7) kg/m2 lower BMI, 4.3% (95% CI 4.0% to 4.5%) lower body fat per cent and 6.4 (95% CI 5.9 to 6.9) cm lower waist circumference, compared with women in the bottom 10th. The patterns were similar in men and also similar to body fat per cent measured by DXA compared with impedance. CONCLUSION: Our findings of approximately twofold stronger associations between physical activity and adiposity with objectively measured than with self-reported physical activity emphasise the need to incorporate objective measures in future studies.


Assuntos
Acelerometria , Tecido Adiposo/diagnóstico por imagem , Composição Corporal , Exercício Físico , Obesidade/epidemiologia , Autorrelato , Absorciometria de Fóton , Adulto , Idoso , Índice de Massa Corporal , Estudos Transversais , Impedância Elétrica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Sobrepeso/epidemiologia , Inquéritos e Questionários , Reino Unido/epidemiologia , Circunferência da Cintura
9.
Pract Radiat Oncol ; 8(4): e239-e248, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29960625

RESUMO

PURPOSE: In patients with non-small cell lung cancer (NSCLC) who undergo trimodality therapy (chemoradiation followed by surgical resection), it is unknown whether limiting preoperative radiation dose to the uninvolved lung reduces postsurgical morbidity. This study evaluated whether radiation fall-off dose parameters to the contralateral lung that is unaffected by NSCLC are associated with postoperative complications in NSCLC patients treated with trimodality therapy. METHODS AND MATERIALS: We retrospectively reviewed NSCLC patients who underwent trimodality therapy between March 2008 and October 2016, with available restored digital radiation plans. Fischer's exact test was used to assess associations between patient and treatment characteristics and the development of treatment-related toxicity. Spearman rank correlation was used to measure the strength of association between dosimetric parameters. RESULTS: Forty-six patients were identified who received trimodality therapy with intensity modulated radiation (median, 59.4 Gy; range, 45-70) and concurrent platinum doublet chemotherapy, followed by surgical resection. The median age was 64.9 years (range, 45.6-81.6). The median follow-up time was 1.9 years (range, 0.3-8.4). Twenty-four (52.2%) patients developed any-grade pulmonary toxicity and 14 (30.4%) patients developed grade 2+ pulmonary toxicity. There was an increased incidence of any-grade pulmonary toxicity in patients with contralateral lung volume receiving at least 20 Gy (V20) ≥7% compared with <7% (90%, n = 9 vs 41.7%, n = 15; P = .01). Similarly, contralateral lung V10 ≥20% was associated with an increased rate of any-grade pulmonary toxicity compared with V10 <20% (80%, n = 12 vs 38.7%, n = 12; P = .01). Pneumonectomy/bilobectomy was associated with grade 2+ pulmonary toxicity (P = .04). CONCLUSIONS: Patients who received a higher radiation fall-off dose volume parameter (V20 ≥7% and V10 ≥20%) to the contralateral uninvolved lung had a higher incidence of any-grade postoperative pulmonary toxicity. Limiting radiation fall-off dose to the uninvolved lung may be an important modifiable radiation parameter in limiting postoperative toxicity in trimodality patients.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/terapia , Pneumopatias/etiologia , Neoplasias Pulmonares/terapia , Lesões por Radiação/etiologia , Dosagem Radioterapêutica , Idoso , Idoso de 80 Anos ou mais , Carcinoma Pulmonar de Células não Pequenas/mortalidade , Carcinoma Pulmonar de Células não Pequenas/cirurgia , Terapia Combinada , Feminino , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/cirurgia , Masculino , Pessoa de Meia-Idade , Pneumonectomia/efeitos adversos , Período Pós-Operatório , Cuidados Pré-Operatórios/métodos , Radioterapia de Intensidade Modulada , Estudos Retrospectivos , Resultado do Tratamento
10.
Int J Cancer ; 143(5): 1037-1046, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-29569713

RESUMO

Body size is an important modifiable risk factor for postmenopausal breast cancer. However, it remains unclear whether direct measures of fat mass are better indicators of risk than anthropometric measures, or whether central adiposity may contribute to risk beyond overall adiposity. We analyzed data from 162,691 postmenopausal women in UK Biobank followed from 2006 to 2014. Body size was measured by trained technicians. Multivariable-adjusted Cox regression was used to estimate relative risks. Analyses were stratified by age at recruitment, region and socioeconomic status, and adjusted for family history of breast cancer, age at menarche, age at first birth, parity, age at menopause, previous hormone replacement therapy use, smoking, alcohol intake, height, physical activity and ethnicity. We observed 2,913 incident invasive breast cancers during a mean 5.7 years of follow-up. There was a continuous increase in risk of postmenopausal breast cancer with increasing adiposity, across all measures. The point estimate, comparing women in the top (median 37.6 kg) to bottom (median 17.6 kg) quartile of body fat mass was 1.70 (95% confidence interval 1.52-1.90). The magnitudes of the associations between per SD increase in BMI and body fat mass with breast cancer risk were similar, suggesting impedance measures of fat were not substantially better indicators of risk than anthropometric measures. After adjusting for body fat mass, the associations between anthropometric measures of central adiposity and breast cancer risk were attenuated. The magnitude of risk, across all measures of adiposity, was greater in women who had been postmenopausal for 12 or more years.


Assuntos
Adiposidade , Bancos de Espécimes Biológicos/estatística & dados numéricos , Neoplasias da Mama/etiologia , Obesidade/complicações , Pós-Menopausa , Adulto , Idoso , Índice de Massa Corporal , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Fatores de Risco , Relação Cintura-Quadril
11.
J Nutr Sci ; 7: e6, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29430297

RESUMO

UK Biobank is an open access prospective cohort of 500 000 men and women. Information on the frequency of consumption of main foods was collected at recruitment with a touchscreen questionnaire; prior to examining the associations between diet and disease, it is essential to evaluate the performance of the dietary touchscreen questionnaire. The objectives of the present paper are to: describe the repeatability of the touchscreen questionnaire in participants (n 20 348) who repeated the assessment centre visit approximately 4 years after recruitment, and compare the dietary touchscreen variables with mean intakes from participants (n 140 080) who completed at least one of the four web-based 24-h dietary assessments post-recruitment. For fish and meat items, 90 % or more of participants reported the same or adjacent category of intake at the repeat assessment visit; for vegetables and fruit, and for a derived partial fibre score (in fifths), 70 % or more of participants were classified into the same or adjacent category of intake (κweighted > 0·50 for all). Participants were also categorised based on their responses to the dietary touchscreen questionnaire at recruitment, and within each category the group mean intake of the same food group or nutrient from participants who had completed at least one web-based 24-h dietary assessment was calculated. The comparison showed that the dietary touchscreen variables, available on the full cohort, reliably rank participants according to intakes of the main food groups.

12.
BMJ Open ; 7(3): e011843, 2017 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-28341684

RESUMO

OBJECTIVES: The objective of this study was to examine if, in the general population, physically active adults have less body fat after taking body mass index (BMI) into account. DESIGN: A cross-sectional analysis of participants recruited into UK Biobank in 2006-2010. SETTING: UK Biobank assessment centres throughout the UK. PARTICIPANTS: 119 230 men and 140 578 women aged 40-69 years, with complete physical activity information, and without a self-reported long-term illness, disability or infirmity. EXPOSURES: Physical activity measured as excess metabolic equivalent (MET)-hours per week, estimated from a combination of walking, and moderate and vigorous physical activity. BMI from measured height and weight. MAIN OUTCOME MEASURE: Body fat percentage estimated from bioimpedance. RESULTS: BMI and body fat percentage were highly correlated (r=0.85 in women; r=0.79 in men), and both were inversely associated with physical activity. Compared with <5 excess MET-hours/week at baseline, ≥100 excess MET-hours/week were associated with a 1.1 kg/m2 lower BMI (27.1 vs 28.2 kg/m2) and 2.8 percentage points lower body fat (23.4% vs 26.3%) in men, and 2.2 kg/m2 lower BMI (25.6 vs 27.7 kg/m2) and 4.0 percentage points lower body fat (33.9% vs 37.9%) in women. For a given BMI, greater physical activity was associated with lower average body fat percentage (for a BMI of 22.5-24.99 kg/m2: 2.0 (95% CI 1.8 to 2.2), percentage points lower body fat in men and 1.8 (95% CI 1.6 to 2.0) percentage points lower body fat in women, comparing ≥100 excess MET-hours per week with <5 excess MET-hours/week). CONCLUSIONS: In this sample of middle-aged adults, drawn from the general population, physical activity was inversely associated with BMI and body fat percentage. For people with the same BMI, those who were more active had a lower body fat percentage.


Assuntos
Tecido Adiposo , Índice de Massa Corporal , Exercício Físico , Adulto , Idoso , Estudos de Coortes , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Reino Unido
13.
Ann Epidemiol ; 25(6): 406-413.e6, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25749558

RESUMO

PURPOSE: Physical activity is thought to protect against obesity, but the evidence is limited and few large studies of this topic have direct, objective measures of several different anthropometric variables. We examined the association of self-reported physical activity with measures of total and central adiposity. METHODS: Our cross-sectional study included 38,201 premenopausal and 94,592 postmenopausal healthy women aged 40 to 70 years in UK Biobank, recruited from 2006 to 2010. RESULTS: Means for total and vigorous physical activity were 31.3 (SD, 30.8) and 9.7 (SD, 14.8) metabolic equivalent h/wk, respectively, for premenopausal and 34.4 (SD, 33.1) and 8.9 (SD, 15.6) metabolic equivalent h/wk, respectively, for postmenopausal women. Multiple linear regression models showed that in both premenopausal and postmenopausal women, body mass index, body fat mass and percentage, trunk fat mass and percentage, waist and hip circumference, and waist-to-hip ratio were lower in women with higher physical activity (P < .0001). Within each category of total physical activity, a larger proportion of vigorous physical activity was associated with lower adiposity (P < .0001). CONCLUSIONS: These findings support the roles of a physically active lifestyle and vigorous exercise in maintaining healthy body size and composition. Higher exercise intensity may be associated with lower adiposity, beyond the influence of exercise frequency and duration.


Assuntos
Composição Corporal , Tamanho Corporal , Exercício Físico , Adiposidade , Adulto , Idoso , Índice de Massa Corporal , Estudos Transversais , Feminino , Humanos , Modelos Lineares , Pessoa de Meia-Idade , Pós-Menopausa , Pré-Menopausa , Reino Unido , Relação Cintura-Quadril
14.
Guang Pu Xue Yu Guang Pu Fen Xi ; 34(5): 1383-7, 2014 May.
Artigo em Chinês | MEDLINE | ID: mdl-25095443

RESUMO

To satisfy the requirement of high speed, real-time and mass data storage etc. for RX anomaly detection of hyperspectral image data, the present paper proposes a solution of multi-DSP parallel processing system for hyperspectral image based on CPCI Express standard bus architecture. Hardware topological architecture of the system combines the tight coupling of four DSPs sharing data bus and memory unit with the interconnection of Link ports. On this hardware platform, by assigning parallel processing task for each DSP in consideration of the spectrum RX anomaly detection algorithm and the feature of 3D data in the spectral image, a 4DSP parallel processing technique which computes and solves the mean matrix and covariance matrix of the whole image by spatially partitioning the image is proposed. The experiment result shows that, in the case of equivalent detective effect, it can reach the time efficiency 4 times higher than single DSP process with the 4-DSP parallel processing technique of RX anomaly detection algorithm proposed by this paper, which makes a breakthrough in the constraints to the huge data image processing of DSP's internal storage capacity, meanwhile well meeting the demands of the spectral data in real-time processing.

15.
Am J Physiol Cell Physiol ; 300(5): C1055-64, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21228318

RESUMO

Gap junction channels, which are made of connexins, are critical for intercellular communication, a function that may be disrupted in a variety of diseases. We studied the consequences of two cataract-associated mutations at adjacent positions at the first extracellular boundary in human connexin50 (Cx50), W45S and G46V. Both of these mutants formed gap junctional plaques when they were expressed in HeLa cells, suggesting that they trafficked to the plasma membrane properly. However, their functional properties differed. Dual two-microelectrode voltage-clamp studies showed that W45S did not form functional intercellular channels in paired Xenopus oocytes or hemichannel currents in single oocytes. When W45S was coexpressed with wild-type Cx50, the mutant acted as a dominant negative inhibitor of wild-type function. In contrast, G46V formed both functional gap junctional channels and hemichannels. G46V exhibited greatly enhanced currents compared with wild-type Cx50 in the presence of physiological calcium concentrations. This increase in hemichannel activity persisted when G46V was coexpressed with wild-type lens connexins, consistent with a dominant gain of hemichannel function for G46V. These data suggest that although these two mutations are in adjacent amino acids, they have very different effects on connexin function and cause disease by different mechanisms: W45S inhibits gap junctional channel function; G46V reduces cell viability by forming open hemichannels.


Assuntos
Catarata/genética , Conexinas/genética , Proteínas do Olho/genética , Mutação , Animais , Sequência de Bases , Cálcio/fisiologia , Catarata/fisiopatologia , Conexinas/fisiologia , Fenômenos Eletrofisiológicos/genética , Proteínas do Olho/fisiologia , Feminino , Junções Comunicantes/genética , Junções Comunicantes/fisiologia , Células HeLa , Humanos , Dados de Sequência Molecular , Técnicas de Patch-Clamp , Xenopus laevis
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