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1.
Proc Natl Acad Sci U S A ; 119(6)2022 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-35110412

RESUMO

The pentose phosphate pathway is a major source of NADPH for oxidative stress resistance in cancer cells but there is limited insight into its role in metastasis, when some cancer cells experience high levels of oxidative stress. To address this, we mutated the substrate binding site of glucose 6-phosphate dehydrogenase (G6PD), which catalyzes the first step of the pentose phosphate pathway, in patient-derived melanomas. G6PD mutant melanomas had significantly decreased G6PD enzymatic activity and depletion of intermediates in the oxidative pentose phosphate pathway. Reduced G6PD function had little effect on the formation of primary subcutaneous tumors, but when these tumors spontaneously metastasized, the frequency of circulating melanoma cells in the blood and metastatic disease burden were significantly reduced. G6PD mutant melanomas exhibited increased levels of reactive oxygen species, decreased NADPH levels, and depleted glutathione as compared to control melanomas. G6PD mutant melanomas compensated for this increase in oxidative stress by increasing malic enzyme activity and glutamine consumption. This generated a new metabolic vulnerability as G6PD mutant melanomas were more dependent upon glutaminase than control melanomas, both for oxidative stress management and anaplerosis. The oxidative pentose phosphate pathway, malic enzyme, and glutaminolysis thus confer layered protection against oxidative stress during metastasis.


Assuntos
Glucosefosfato Desidrogenase/metabolismo , Glutamina/metabolismo , Melanoma/metabolismo , Estresse Oxidativo/fisiologia , Animais , Humanos , Camundongos , Camundongos Endogâmicos NOD , NADP/metabolismo , Oxirredução , Via de Pentose Fosfato/fisiologia , Espécies Reativas de Oxigênio/metabolismo
2.
J Anim Ecol ; 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38946701

RESUMO

Among migratory vertebrates, high levels of fidelity to non-breeding sites during adulthood are common. If occupied sites vary in quality, strong site fidelity can have profound consequences for individual fitness and population demography. Given the prevalence of adult site fidelity, the regions of the non-breeding range to which juveniles first migrate, and the scale of any subsequent movements, are likely to be pivotal in shaping distributions and demographic processes across population ranges. However, inherent difficulties in tracking migratory individuals through early life mean that opportunities to quantify juvenile settlement and movements across non-breeding ranges, and the mechanisms involved, are extremely rare. Through long-term, range-wide resightings of hundreds of colour-marked individuals from their first migration to adulthood and the application of state-space models, we quantify levels of juvenile and adult regional-scale movements and distances at different life stages across the whole non-breeding distribution range in a migratory shorebird, the Black-tailed Godwit (Limosa limosa islandica). We show that the probability of individuals changing non-breeding regions (seven historical wintering regions spanning the Western Europe range) at all ages is very low (mean movement probability = 10.9% from first to subsequent winter, and 8.3% from first adult winter to later winters). Movement between regions was also low between autumn and winter of the same year for both juveniles (mean movement probability = 17.0%) and adults (10.4%). The great majority of non-breeding movements from the first autumn to adulthood were within regions and less than 100 km. The scarcity of regional-scale non-breeding movements from the first autumn to adulthood means that the factors influencing where juveniles settle will be key determinants of non-breeding distributions and of the rate and direction of changes in distributions.

3.
J Drugs Dermatol ; 23(5): 311-315, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38709695

RESUMO

PURPOSE: In this review article, we sought to elucidate how the social determinants of health, including socioeconomic status, education, neighborhood or physical environment, access to healthcare, and race/ethnicity, affect the likelihood of receiving immunotherapy, a novel and expensive treatment for melanoma.  Methods: The PubMed database was queried up to May 2023, for studies pertaining to health disparities in melanoma, including studies examining the utilization of immunotherapy agents for the treatment of melanoma across various social determinants of health. RESULTS: Disparities in the utilization of immunotherapy exist across various social determinants. A total of 10 studies were found to report on disparities in receipt of immunotherapy. These studies reported an association between insurance status, education level, socioeconomic status, as well as proximity to a cancer research center, and a lower likelihood of receiving immunotherapy. CONCLUSION: As the number of novel immunotherapy drugs grows, it is important to understand the various disparities affecting the delivery of immunotherapy across social determinants. The findings from this study can help to drive public health policy aimed at addressing inequities in the treatment of melanoma as well as other cancers.    J Drugs Dermatol. 2024;23(5):311-315. doi:10.36849/JDD.7803.


Assuntos
Acessibilidade aos Serviços de Saúde , Disparidades em Assistência à Saúde , Imunoterapia , Melanoma , Neoplasias Cutâneas , Determinantes Sociais da Saúde , Humanos , Melanoma/terapia , Imunoterapia/métodos , Disparidades em Assistência à Saúde/estatística & dados numéricos , Neoplasias Cutâneas/terapia , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Classe Social
4.
J Anim Ecol ; 91(7): 1416-1430, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35385132

RESUMO

Changes in phenology and distribution are being widely reported for many migratory species in response to shifting environmental conditions. Understanding these changes and the situations in which they occur can be aided by understanding consistent individual differences in phenology and distribution and the situations in which consistency varies in strength or detectability. Studies tracking the same individuals over consecutive years are increasingly reporting migratory timings to be a repeatable trait, suggesting that flexible individual responses to environmental conditions may contribute little to population-level changes in phenology and distribution. However, how this varies across species and sexes, across the annual cycle and in relation to study (tracking method, study design) and/or ecosystem characteristics is not yet clear. Here, we take advantage of the growing number of publications in movement ecology to perform a phylogenetic multilevel meta-analysis of repeatability estimates for avian migratory timings to investigate these questions. Of 2,433 reviewed studies, 54 contained suitable information for meta-analysis, resulting in 177 effect sizes from 47 species. Individual repeatability of avian migratory timings averaged 0.414 (95% confidence interval: 0.3-0.5) across landbirds, waterbirds and seabirds, suggesting consistent individual differences in migratory timings is a common feature of migratory systems. Timing of departure from the non-breeding grounds was more repeatable than timings of arrival at or departure from breeding grounds, suggesting that conditions encountered on migratory journeys and outcome of breeding attempts can influence individual variation. Population-level shifts in phenology could arise through individual timings changing with environmental conditions and/or through shifts in the numbers of individuals with different timings. Our findings suggest that, in addition to identifying the conditions associated with individual variation in phenology, exploring the causes of between-individual variation will be key in predicting future rates and directions of changes in migratory timings. We therefore encourage researchers to report the within- and between- individual variance components underpinning the reported repeatability estimates to aid interpretation of migration behaviour. In addition, the lack of studies in the tropics means that levels of repeatability in less strongly seasonal environments are not yet clear.


Assuntos
Migração Animal , Ecossistema , Animais , Aves , Filogenia , Estações do Ano
5.
Nutr Health ; 28(3): 389-400, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35108144

RESUMO

Background: Having low-income limits one's ability to purchase foods that are high in nutritional value (e.g. vegetables and fruits (V/F)). Higher V/F intake is associated with less diet-related chronic disease. Food pharmacy programs are potential solutions to providing V/F to low-income populations with or at-risk for chronic disease. Aim: This systematic review aimed to determine the effect of food pharmacy programs, including interventions targeting populations at-risk for chronic disease. Methods: We searched Pubmed and Google Scholar databases for studies reporting on food pharmacy interventions and outcomes (hemoglobin A1c, body mass index (BMI), V/F intake, and blood pressure). We calculated pooled mean differences using a random-effects model. Seventeen studies met our inclusion criteria; 13 studies used a pre/post study design, three used a randomized controlled trial, and one was a post-survey only. Results: We found that the pooled mean daily servings of V/F (0.77; 95% CI: 0.30 to 1.24) was higher and BMI (-0.40; 95% CI: -0.50 to -0.31) was lower with food pharmacy interventions We did not find any differences in the pooled mean differences for hemoglobin A1c or systolic blood pressure. Conclusion: Findings posit that food pharmacy programs delivered to primarily low-income individuals with comorbidities may be a promising solution to improving V/F intake and possibly overall diet in these populations.


Assuntos
Doença Crônica , Dieta , Gerenciamento Clínico , Frutas , Hemoglobinas Glicadas , Humanos , Pobreza , Prescrições , Ensaios Clínicos Controlados Aleatórios como Assunto , Verduras
6.
Int J Cancer ; 148(3): 713-722, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-32700797

RESUMO

We assessed the frequency that oncology drugs approved by the U.S. Food and Drug Administration (FDA) based on a single-arm study when there is already evidence of existing and available treatments. For this, we conducted a retrospective cross-sectional analysis of FDA-approved oncology drugs based on a single-arm study. All FDA announcements for all oncology drugs approved from May 2014 through June 2019 on a single-arm trial were included. We then performed a systematic search in PubMed, looking for studies on other drugs for the same indication as the FDA drug approval. For the 60 indications, we found 38 instances (63%) of existing therapies being used for the same indication. Of those, we found that 20 drugs were approved based upon a response rate lower than response rates of existing therapies in the same indication. Among oncology drugs that were FDA-approved based on a single-arm study, we found evidence of existing, available therapies being used for the same indication as the FDA-approved drug in the majority of indications (63%), and in one-third of all indications, the response rates for existing therapies were numerically better than the FDA-approved drug. These results suggest that there are inconsistencies in the standards set for oncology drug approvals, and many uncontrolled trials leading to drug approvals could have contemporary controls for which equipoise exists.


Assuntos
Antineoplásicos/uso terapêutico , Aprovação de Drogas/organização & administração , Neoplasias/tratamento farmacológico , United States Food and Drug Administration/normas , Estudos Transversais , Tomada de Decisões , Humanos , Vigilância de Produtos Comercializados , Estudos Retrospectivos , Resultado do Tratamento , Estados Unidos
7.
Proc Biol Sci ; 288(1946): 20202955, 2021 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-33653129

RESUMO

Wildlife conservation policies directed at common and widespread, but declining, species are difficult to design and implement effectively, as multiple environmental changes are likely to contribute to population declines. Conservation actions ultimately aim to influence demographic rates, but targeting actions towards feasible improvements in these is challenging in widespread species with ranges that encompass a wide range of environmental conditions. Across Europe, sharp declines in the abundance of migratory landbirds have driven international calls for action, but actions that could feasibly contribute to population recovery have yet to be identified. Targeted actions to improve conditions on poor-quality sites could be an effective approach, but only if local conditions consistently influence local demography and hence population trends. Using long-term measures of abundance and demography of breeding birds at survey sites across Europe, we show that co-occurring species with differing migration behaviours have similar directions of local population trends and magnitudes of productivity, but not survival rates. Targeted actions to boost local productivity within Europe, alongside large-scale (non-targeted) environmental protection across non-breeding ranges, could therefore help address the urgent need to halt migrant landbird declines. Such demographic routes to recovery are likely to be increasingly needed to address global wildlife declines.


Assuntos
Migração Animal , Aves , Animais , Conservação dos Recursos Naturais , Europa (Continente) , Dinâmica Populacional
8.
BMC Cancer ; 21(1): 889, 2021 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-34344325

RESUMO

BACKGROUND: Identifying ineffective practices that have been used in oncology is important in reducing wasted resources and harm. We sought to examine the prevalence of practices that are being used but have been shown in RCTs to be ineffective (medical reversals) in published oncology studies. METHODS: We cross-sectionally analyzed studies published in three high-impact oncology medical journals (2009-2018). We abstracted data relating to the frequency and characterization of medical reversals. RESULTS: Of the 64 oncology reversals, medications (44%) represented the most common intervention type (39% were targeted). Fourteen (22%) were funded by pharmaceutical/industry only and 56% were funded by an organization other than pharmaceutical/industry. The median number of years that the practice had been in use prior to the reversal study was 9 years (range 1-50 years). CONCLUSION: Here we show that oncology reversals most often involve the administration of medications, have been practiced for years, and are often identified through studies funded by non-industry organizations.


Assuntos
Oncologia , Publicações Periódicas como Assunto/estatística & dados numéricos , Publicações/estatística & dados numéricos , Pesquisa/estatística & dados numéricos , Pesquisa/normas , Estudos Transversais , Humanos , Oncologia/estatística & dados numéricos , Publicações/normas
9.
J Natl Compr Canc Netw ; 18(2): 161-167, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32023529

RESUMO

BACKGROUND: Noninferiority (NI) trials should help identify interventions that offer some benefit (eg, lower financial costs, more tolerable, or less invasive) without sacrificing noticeable effectiveness, and researchers should adhere to appropriate standards in the conduct and reporting of methods. This study describes the characteristics of a systematic sampling of NI studies from an updated search of recent published oncology trials. METHODS: We performed a cross-sectional analysis of NI research published between 2014 and 2018 in the top 3 medical journals and top 3 oncology journals. We estimated the percentage of NI trials in oncology that report informative details of study, such as justification for conducting NI trial, justification of NI margin, analysis population, and alpha level. RESULTS: There were 94 NI studies and 104 comparisons, and 59.6% (n=62) of comparisons declared NI. The median NI margin of comparisons reporting an odds or hazard ratio was 1.3 (1.05-3.2; n=64). Twenty-three percent (n=22) of studies did not provide a justification for conducting a NI study; 54.3% (n=51) of studies did not provide a justification of the margin they used in their study. Only approximately 46% (n=43) of comparisons used both an intention-to-treat (ITT) and per-protocol (PP) analysis, and 37.3% (n=35) of studies used a one-sided alpha level of >.025. There is notable variation in key elements of the conduct and reporting of NI trials, including the NI margin, the alpha level, and the population analyzed. Furthermore, a high number of studies do not provide justification for conducting a NI study or the margin used for determining NI. CONCLUSIONS: These results suggest that there is room for improvement in the reporting and conduct of NI trials in oncology.


Assuntos
Estudos de Equivalência como Asunto , Oncologia/normas , Neoplasias/terapia , Projetos de Pesquisa/normas , Humanos , Oncologia/métodos , Resultado do Tratamento
11.
Future Oncol ; 14(17): 1701-1710, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29543521

RESUMO

AIM: To better understand the hepatocellular carcinoma (HCC) patient journey, we conducted a patient survey across 13 countries. METHODS: The survey included closed- and open-ended questions developed using an iterative process to gather information on demographics, diagnosis and treatment. Patients self-selected or were directed to the online survey by their doctor. RESULTS: A total of 256 patients completed the survey. More than two-thirds (68%) felt they did not receive enough information about HCC at diagnosis. Treatments included oral anticancer therapy, transarterial chemoembolization (TACE), and selective internal radiation therapy (SIRT). A total of 81% receiving sorafenib, 45% receiving SIRT and 32% receiving TACE reported impaired quality-of-life (QoL). A total of 42, 19 and 0% of patients using sorafenib rated their current QoL as 'poor', 'good' and 'excellent', respectively; compared with SIRT (22, 33 and 6%) or TACE (11, 37 and 13%). CONCLUSION: Most patients with HCC require additional accessible information. People with incurable HCC require treatments that preserve QoL.


Assuntos
Carcinoma Hepatocelular/terapia , Neoplasias Hepáticas/terapia , Qualidade de Vida , Inquéritos e Questionários , Adulto , Idoso , Idoso de 80 Anos ou mais , Terapia Combinada , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Adulto Jovem
12.
Ecol Lett ; 19(3): 308-17, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26807694

RESUMO

Declines in migratory species are a pressing concern worldwide, but the mechanisms underpinning these declines are not fully understood. We hypothesised that species with greater within-population variability in migratory movements and destinations, here termed 'migratory diversity', might be more resilient to environmental change. To test this, we related map-based metrics of migratory diversity to recent population trends for 340 European breeding birds. Species that occupy larger non-breeding ranges relative to breeding, a characteristic we term 'migratory dispersion', were less likely to be declining than those with more restricted non-breeding ranges. Species with partial migration strategies (i.e. overlapping breeding and non-breeding ranges) were also less likely to be declining than full migrants or full residents, an effect that was independent of migration distance. Recent rates of advancement in Europe-wide spring arrival date were greater for partial migrants than full migrants, suggesting that migratory diversity may also help facilitate species responses to climate change.


Assuntos
Distribuição Animal , Migração Animal , Aves/fisiologia , Animais , Mudança Climática , Europa (Continente) , Dinâmica Populacional , Estações do Ano
14.
Proc Biol Sci ; 283(1842)2016 11 16.
Artigo em Inglês | MEDLINE | ID: mdl-27807267

RESUMO

Across Europe, rapid population declines are ongoing in many Afro-Palaearctic migratory bird species, but the development of appropriate conservation actions across such large migratory ranges is severely constrained by lack of understanding of the demographic drivers of these declines. By constructing regional integrated population models (IPMs) for one of the suite of migratory species that is declining in the southeast of Britain but increasing in the northwest, we show that, while annual population growth rates in both regions vary with adult survival, the divergent regional trajectories are primarily a consequence of differences in productivity. Between 1994 and 2012, annual survival and productivity rates ranged over similar levels in both regions, but high productivity rates were rarer in the declining southeast population and never coincided with high survival rates. By contrast, population growth in the northwest was fuelled by several years in which higher productivity coincided with high survival rates. Simulated population trajectories suggest that realistic improvements in productivity could have reversed the decline (i.e. recovery of the population index to more than or equal to 1) in the southeast. Consequently, actions to improve productivity on European breeding grounds are likely to be a more fruitful and achievable means of reversing migrant declines than actions to improve survival on breeding, passage or sub-Saharan wintering grounds.


Assuntos
Migração Animal , Aves , África Subsaariana , Animais , Conservação dos Recursos Naturais , Dinâmica Populacional , Estações do Ano , Reino Unido
15.
J Anim Ecol ; 85(5): 1298-306, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27390034

RESUMO

Male-biased sex ratios occur in many bird species, particularly in those with small or declining populations, but the causes of these skews and their consequences for local population demography are rarely known. Within-species variation in sex ratios can help to identify the demographic and behavioural processes associated with such biases. Small populations may be more likely to have skewed sex ratios if sex differences in survival, recruitment or dispersal vary with local abundance. Analyses of species with highly variable local abundances can help to identify these mechanisms and the implications for spatial variation in demography. Many migratory bird species are currently undergoing rapid and severe declines in abundance in parts of their breeding ranges and thus have sufficient spatial variation in abundance to explore the extent of sex ratio biases, their causes and implications. Using national-scale bird ringing data for one such species (willow warbler, Phylloscopus trochilus), we show that sex ratios vary greatly across Britain and that male-biased sites are more frequent in areas of low abundance, which are now widespread across much of south and east England. These sex ratio biases are sufficient to impact local productivity, as the relative number of juveniles caught at survey sites declines significantly with increasing sex ratio skew. Sex differences in survival could influence this sex ratio variation, but we find little evidence for sex differences in survival increasing with sex ratio skew. In addition, sex ratios have become male-biased over the last two decades, but there are no such trends in adult survival rates for males or females. This suggests that lower female recruitment into low abundance sites is contributing to these skews. These findings suggest that male-biased sex ratios in small and declining populations can arise through local-scale sex differences in survival and dispersal, with females recruiting disproportionately into larger populations. Given the high level of spatial variation in population declines and abundance of many migratory bird species across Europe at present, male-biased small populations may be increasingly common. As singing males are the primary records used in surveys of these species, and as unpaired males often sing throughout the breeding season, local sex ratio biases could also be masking the true extent of these population declines.


Assuntos
Longevidade , Reprodução , Razão de Masculinidade , Aves Canoras/fisiologia , Migração Animal , Animais , Feminino , Geografia , Masculino , Densidade Demográfica , Estações do Ano
16.
J Anim Ecol ; 84(5): 1141-3, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26376431

RESUMO

The way that animal populations respond to changing weather conditions is a major focus of current research, fuelled by the need to predict the future consequences of climatic changes. Severe weather events can provide valuable opportunities to uncover the mechanisms through which the weather influences population demography but opportunities to track individual responses to such events are rare. Senner et al. (2015) report on an exceptional opportunity to address this issue, when their detailed studies of a migratory shorebird population were interrupted by an extreme weather event that coincided with spring migration, a key period in the annual cycle of migratory species. Through tracking of individuals across the migratory range, Senner et al. (2015) show that, while individual schedules were severely disrupted by the harsh weather, with many individuals undertaking reverse migrations and experiencing delayed breeding, breeding success was unaffected. This study highlights the complexities involved in predicting the ecological consequences of extreme weather events and the key role of behavioural flexibility in mitigating the costs to individuals.


Assuntos
Migração Animal , Charadriiformes/fisiologia , Temperatura Baixa , Reprodução , Animais , Feminino , Masculino
17.
Lancet Oncol ; 15(6): e205-12, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24731885

RESUMO

Cancer can have profound social and economic consequences for people in India, often leading to family impoverishment and societal inequity. Reported age-adjusted incidence rates for cancer are still quite low in the demographically young country. Slightly more than 1 million new cases of cancer are diagnosed every year in a population of 1.2 billion. In age-adjusted terms this represents a combined male and female incidence of about a quarter of that recorded in western Europe. However, an estimated 600,000-700,000 deaths in India were caused by cancer in 2012. In age-standardised terms this figure is close to the mortality burden seen in high-income countries. Such figures are partly indicative of low rates of early-stage detection and poor treatment outcomes. Many cancer cases in India are associated with tobacco use, infections, and other avoidable causes. Social factors, especially inequalities, are major determinants of India's cancer burden, with poorer people more likely to die from cancer before the age of 70 years than those who are more affluent. In this first of three papers, we examine the complex epidemiology of cancer, the future burden, and the dominant sociopolitical themes relating to cancer in India.


Assuntos
Neoplasias/epidemiologia , Distribuição por Idade , Efeitos Psicossociais da Doença , Feminino , Humanos , Índia/epidemiologia , Masculino , Neoplasias/etiologia , Distribuição por Sexo , Fatores Socioeconômicos
18.
Lancet ; 392(10149): 716-717, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-30191816
19.
Proc Biol Sci ; 281(1774): 20132161, 2014 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-24225454

RESUMO

Recent advances in spring arrival dates have been reported in many migratory species but the mechanism driving these advances is unknown. As population declines are most widely reported in species that are not advancing migration, there is an urgent need to identify the mechanisms facilitating and constraining these advances. Individual plasticity in timing of migration in response to changing climatic conditions is commonly proposed to drive these advances but plasticity in individual migratory timings is rarely observed. For a shorebird population that has significantly advanced migration in recent decades, we show that individual arrival dates are highly consistent between years, but that the arrival dates of new recruits to the population are significantly earlier now than in previous years. Several mechanisms could drive advances in recruit arrival, none of which require individual plasticity or rapid evolution of migration timings. In particular, advances in nest-laying dates could result in advanced recruit arrival, if benefits of early hatching facilitate early subsequent spring migration. This mechanism could also explain why arrival dates of short-distance migrants, which generally return to breeding sites earlier and have greater scope for advance laying, are advancing more rapidly than long-distance migrants.


Assuntos
Adaptação Fisiológica , Migração Animal , Aves/fisiologia , Mudança Climática , Animais , Geografia , Comportamento de Nidação , Dinâmica Populacional , Estações do Ano , Fatores de Tempo
20.
Blood ; 120(2): 335-46, 2012 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-22665933

RESUMO

Myeloid ecotropic viral integration site 1 (Meis1) forms a heterodimer with Pbx1 that augments Hox-dependent gene expression and is associated with leukemogenesis and HSC self-renewal. Here we identified 2 independent actions of Meis1 in hematopoietic development: one regulating cellular proliferation and the other involved in megakaryocyte lineage development. First, we found that endogenous Mesp1 indirectly induces Meis1 and Meis2 in endothelial cells derived from embryonic stem cells. Overexpression of Meis1 and Meis2 greatly enhanced the formation of hematopoietic colonies from embryonic stem cells, with the exception of erythroid colonies, by maintaining hematopoietic progenitor cells in a state of proliferation. Second, overexpression of Meis1 repressed the development of early erythroid progenitors, acting in vivo at the megakaryocyte-erythroid progenitor stage to skew development away from erythroid generation and toward megakaryocyte development. This previously unrecognized action of Meis1 may explain the embryonic lethality observed in Meis1(-/-) mice that arises from failure of lymphatic-venous separation and can result as a consequence of defective platelet generation. These results show that Meis1 exerts 2 independent functions, with its role in proliferation of hematopoietic progenitors acting earlier in development from its influence on the fate choice at the megakaryocyte-erythroid progenitor between megakaryocytic and erythroid development.


Assuntos
Células Precursoras Eritroides/citologia , Células Precursoras Eritroides/fisiologia , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/fisiologia , Proteínas de Homeodomínio/fisiologia , Proteínas de Neoplasias/fisiologia , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/fisiologia , Linhagem Celular , Linhagem da Célula/genética , Linhagem da Célula/fisiologia , Proliferação de Células , Ensaio de Unidades Formadoras de Colônias , Eritropoese/genética , Eritropoese/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Hematopoese/genética , Hematopoese/fisiologia , Proteínas de Homeodomínio/genética , Megacariócitos/citologia , Megacariócitos/fisiologia , Camundongos , Camundongos Knockout , Proteína Meis1 , Proteínas de Neoplasias/deficiência , Proteínas de Neoplasias/genética , Isoformas de Proteínas/genética , Isoformas de Proteínas/fisiologia , Transdução de Sinais
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