RESUMEN

Plants flower in response to environmental signals. These signals change the shape and developmental identity of the shoot apical meristem (SAM), causing it to form flowers and inflorescences. We show that the increases in SAM width and height during floral transition correlate with changes in size of the central zone (CZ), defined by CLAVATA3 expression, and involve a transient increase in the height of the organizing center (OC), defined by WUSCHEL expression. The APETALA2 (AP2) transcription factor is required for the rapid increases in SAM height and width, by maintaining the width of the OC and increasing the height and width of the CZ. AP2 expression is repressed in the SAM at the end of floral transition, and extending the duration of its expression increases SAM width. Transcriptional repression by SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) represents one of the mechanisms reducing AP2 expression during floral transition. Moreover, AP2 represses SOC1 transcription, and we find that reciprocal repression of SOC1 and AP2 contributes to synchronizing precise changes in meristem shape with floral transition.

Asunto(s)

Proteínas de Arabidopsis , Arabidopsis , Flores , Regulación de la Expresión Génica de las Plantas , Proteínas de Homeodominio , Proteínas de Dominio MADS , Meristema , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Meristema/metabolismo , Meristema/crecimiento & desarrollo , Meristema/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Flores/genética , Flores/crecimiento & desarrollo , Flores/metabolismo , Proteínas de Homeodominio/metabolismo , Proteínas de Homeodominio/genética , Proteínas de Dominio MADS/metabolismo , Proteínas de Dominio MADS/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Regulación del Desarrollo de la Expresión Génica , Plantas Modificadas Genéticamente

RESUMEN

Antascomicin B is a natural product that similarly to the macrolides FK506 and Rapamycin binds to the FK506-binding protein 12 (FKBP12). FK506 and Rapamycin act as molecular glues by inducing ternary complexes between FKBPs and additional target proteins. Whether Antascomicin B can induce ternary complexes is unknown. Here we show that Antascomicin B binds tightly to larger human FKBP homologs. The cocrystal structure of FKBP51 in complex with Antascomicin B revealed that large parts of Antascomicin B are solvent-exposed and available to engage additional proteins. Cellular studies demonstrated that Antascomicin B enhances the interaction between human FKBP51 and human Akt. Our studies show that molecules with molecular glue-like properties are more prominent in nature than previously thought. We predict the existence of additional 'orphan' molecular glues that evolved to induce ternary protein complexes but where the relevant ternary complex partners are unknown.

Asunto(s)

Proteínas Proto-Oncogénicas c-akt , Proteínas de Unión a Tacrolimus , Tacrolimus , Humanos , Proteínas Proto-Oncogénicas c-akt/metabolismo , Sirolimus/farmacología , Tacrolimus/farmacología , Tacrolimus/análogos & derivados , Proteínas de Unión a Tacrolimus/química , Proteínas de Unión a Tacrolimus/metabolismo

RESUMEN

BACKGROUND: Complex traits, such as growth and fitness, are typically controlled by a very large number of variants, which can interact in both additive and non-additive fashion. In an attempt to gauge the relative importance of both types of genetic interactions, we turn to hybrids, which provide a facile means for creating many novel allele combinations. RESULTS: We focus on the interaction between alleles of the same locus, i.e., dominance, and perform a transcriptomic study involving 141 random crosses between different accessions of the plant model species Arabidopsis thaliana. Additivity is rare, consistently observed for only about 300 genes enriched for roles in stress response and cell death. Regulatory rare-allele burden affects the expression level of these genes but does not correlate with F1 rosette size. Non-additive, dominant gene expression in F1 hybrids is much more common, with the vast majority of genes (over 90%) being expressed below the parental average. Unlike in the additive genes, regulatory rare-allele burden in the dominant gene set is strongly correlated with F1 rosette size, even though it only mildly covaries with the expression level of these genes. CONCLUSIONS: Our study underscores under-dominance as the predominant gene action associated with emergence of rosette growth trajectories in the A. thaliana hybrid model. Our work lays the foundation for understanding molecular mechanisms and evolutionary forces that lead to dominance complementation of rare regulatory alleles.

Asunto(s)

Arabidopsis , Alelos , Arabidopsis/genética , Evolución Biológica , Epistasis Genética , Transcriptoma , Carácter Cuantitativo Heredable

RESUMEN

Prevalent findings of anticoagulant rodenticide (AR) residues in liver tissue of freshwater fish recently emphasized the existence of aquatic exposure pathways. Thus, a comprehensive wastewater treatment plant and surface water monitoring campaign was conducted at two urban catchments in Germany in 2018 and 2019 to investigate potential emission sources of ARs into the aquatic environment. Over several months, the occurrence and fate of all eight ARs authorized in the European Union as well as two pharmaceutical anticoagulants was monitored in a variety of aqueous, solid, and biological environmental matrices during and after widespread sewer baiting with AR-containing bait. As a result, sewer baiting in combined sewer systems, besides outdoor rodent control at the surface, was identified as a substantial contributor of these biocidal active ingredients in the aquatic environment. In conjunction with heavy or prolonged precipitation during bait application in combined sewer systems, a direct link between sewer baiting and AR residues in wastewater treatment plant influent, effluent, and the liver of freshwater fish was established. Moreover, study results confirmed insufficient removal of anticoagulants during conventional wastewater treatment and thus indirect exposure of aquatic organisms in receiving streams via tertiary treated effluents and combined sewer overflows. Nevertheless, further research is required to determine the ecological implications and risks for aquatic organisms as well as fish-eating predators from chronic AR exposure at environmentally relevant concentrations.

Asunto(s)

Rodenticidas , Animales , Anticoagulantes , Monitoreo del Ambiente , Alemania , Control de Roedores , Aguas Residuales

RESUMEN

This study investigated whether cell-based bioassays were suitable to characterize profiles of mixture effects of hydrophobic pollutants in multiple sediments covering remote Arctic and tropical sites to highly populated sites in Europe and Australia. The total contamination was determined after total solvent extraction and the bioavailable contamination after silicone-based passive equilibrium sampling. In addition to cytotoxicity, we observed specific responses in cell-based reporter gene bioassays: activation of metabolic enzymes (arylhydrocarbon receptor: AhR, peroxisome proliferator activated receptor gamma: PPARγ) and adaptive stress responses (oxidative stress response: AREc32). No mixture effects were found for effects on the estrogen, androgen, progesterone and glucocorticoid receptors, or they were masked by cytotoxicity. The bioanalytical equivalent concentrations (BEQ) spanned several orders of magnitude for each bioassay. The bioavailable BEQs (passive equilibrium sampling) typically were 10-100 times and up to 420 times lower than the total BEQ (solvent extraction) for the AhR and AREc32 assays, indicating that the readily desorbing fraction of the bioactive chemicals was substantially lower than the fraction bound strongly to the sediment sorptive phases. Contrarily, the bioavailable BEQ in the PPARγ assay was within a factor of five of the total BEQ. We identified several hotspots of contamination in Europe and established background contamination levels in the Arctic and Australia.

Asunto(s)

Bioensayo/métodos , Monitoreo del Ambiente/métodos , Sedimentos Geológicos/química , Contaminantes Químicos del Agua/análisis , Regiones Árticas , Australia , Clima Frío , Europa (Continente) , Manejo de Especímenes , Clima Tropical

RESUMEN

BACKGROUND: Chemical quality of sediment and suspended particulate matter (SPM) is usually assessed by total chemical concentrations (Ctotal). However, the freely dissolved concentration (Cfree) is the ecologically more relevant parameter for bioavailability, diffusion and bioaccumulation. In recent studies, equilibrium sampling has been applied to determine Cfree of hydrophobic organic contaminants (HOCs) in the sediment pore water, whereas such data are missing for SPM. We applied solid-phase micro-extraction to measure and compare Cfree of PAHs and PCBs in pore water of sediments and SPM sampled along the German part of the river Elbe. Moreover, site-specific distribution ratios were evaluated and Cbio,lipid was predicted using Cfree. RESULTS: Cfree of PAHs remained largely constant while Cfree of PCBs varied along the Elbe River. The highest Ctotal of PCBs and PAHs were found at Prossen (km 13) and Meißen (km 96). PCB Ctotal even exceeded the environmental quality standard for sediment and SPM in Prossen. Site-specific distribution ratios (KD) revealed a stronger sorption for PAHs compared to PCBs, indicating a higher availability of PCBs. Equilibrium partitioning concentrations in lipids (Clip↔sed) showed a high correlation with actually measured lipid-normalised concentrations (Cbio,lipid) in bream. This indicates that PCB bioaccumulation in this benthic fish species is closely linked to the sediment contamination. CONCLUSIONS: In rivers, SPM functions as a transportation vehicle for HOCs along the stream until it eventually deposits to the sediment. This study demonstrates that due to weaker sorption of PAHs and PCBs to the SPM this matrix poses a higher risk to the aquatic environment compared to the sediment. The prediction of Cbio,lipid of PCBs was correct and shows that solid-phase micro-extraction is highly suited to predict lipid concentration, and thus a valuable tool for risk-assessment or sediment management.

RESUMEN

Plants modify organ growth and tune morphogenesis in response to various endogenous and environmental cues. At the cellular level, organ growth is often adjusted by alterations in cell growth, but the molecular mechanisms underlying this control remain poorly understood. In this study, we identify the DNA BINDING WITH ONE FINGER (DOF)-type transcription regulator OBF BINDING PROTEIN4 (OBP4) as a repressor of cell growth. Ectopic expression of OBP4 in Arabidopsis (Arabidopsis thaliana) inhibits cell growth, resulting in severe dwarfism and the repression of genes involved in the regulation of water transport, root hair development, and stress responses. Among the basic helix-loop-helix transcription factors known to control root hair growth, OBP4 binds the ROOT HAIR DEFECTIVE6-LIKE2 (RSL2) promoter to repress its expression. The accumulation of OBP4 proteins is detected in expanding root epidermal cells, and its expression level is increased by the application of abscisic acid (ABA) at concentrations sufficient to inhibit root hair growth. ABA-dependent induction of OBP4 is associated with the reduced expression of RSL2 Furthermore, ectopic expression of OBP4 or loss of RSL2 function results in ABA-insensitive root hair growth. Taken together, our results suggest that OBP4-mediated transcriptional repression of RSL2 contributes to the ABA-dependent inhibition of root hair growth in Arabidopsis.

Asunto(s)

Ácido Abscísico/farmacología , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas de Unión al ADN/genética , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Raíces de Plantas/genética , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/metabolismo , Proteínas de Unión al ADN/metabolismo , Microscopía Confocal , Mutación , Epidermis de la Planta/genética , Epidermis de la Planta/metabolismo , Reguladores del Crecimiento de las Plantas/farmacología , Raíces de Plantas/crecimiento & desarrollo , Plantas Modificadas Genéticamente , Regiones Promotoras Genéticas/genética , Unión Proteica , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa

RESUMEN

The combination of polymer-based passive sampling to collect complex environmental mixtures of pollutants, the transfer of these mixtures into bioassays, and their related toxicological characterization is still in its infancy. However, this approach has considerable potential to improve environmental hazard and risk assessment for two reasons. First, the passive sampler collects a broad range of chemicals representing the fraction of compounds available for diffusion and (bio)uptake, excluding a large part of the matrix; thus, extensive sample cleanup which could discriminate certain compounds can be avoided. Second, the toxicological characterization of samples using bioassays is complementary to chemical (target) analysis within environmental monitoring because it captures all chemicals exerting the same mode of toxic action and acting jointly in mixtures, thus providing a comprehensive picture of their overall combined effects. The scientific literature describes a range of examples from the water phase where passive sampling is usually carried out in the kinetic uptake regime for most chemicals although some may already have reached equilibrium. The composition of the chemical mixture changes from the water phase to the passive sampling material because of kinetic effects and polymer/water partition coefficients which depend on the chemicals' hydrophobicity. In contrast, only a few applications in sediment and biota have been described, but amongst these some pioneering studies have demonstrated the feasibility and potential of this combined approach. This chapter gives an overview of what has been carried out in this research area, focusing on opportunities and challenges, and points out desirable future developments with a focus on the importance of choosing a suitable combination of sampling and dosing to transfer (or re-establish) the environmental mixture into the bioassay.

Asunto(s)

Mezclas Complejas/aislamiento & purificación , Mezclas Complejas/toxicidad , Monitoreo del Ambiente/métodos , Manejo de Especímenes/métodos , Pruebas de Toxicidad/métodos , Contaminantes del Agua/aislamiento & purificación , Contaminantes del Agua/toxicidad , Bioensayo/métodos , Filtración/métodos , Agua/química

RESUMEN

Toxicity testing using in vitro bioassays is assuming an increasingly important role. Nevertheless, several issues remain with regard to their proper application, which mainly relate to the proper definition and control of the test chemical(s) concentrations to which the cells or tissues are exposed. This has fundamental implications for understanding the underlying relationship between the in vitro exposure regime and response, and leads to uncertainty in the resulting bioassay data. This chapter covers the definition and control of exposure of hydrophobic organic chemicals (HOCs) in in vitro bioassays aimed at measuring their toxicity. A review of the fate of HOCs in typical in vitro set-ups is followed by a discussion of how to define the test exposure. Currently applied approaches for introducing HOCs into in vitro bioassays are then related to these different definitions of test exposure. Finally, passive dosing as one possible approach for giving defined and constant dissolved concentrations of HOCs in in vitro toxicity tests is introduced, using examples taken from the literature, and how this might be better integrated into high throughput in vitro toxicity testing is discussed.

Asunto(s)

Relación Dosis-Respuesta a Droga , Compuestos Orgánicos/química , Compuestos Orgánicos/toxicidad , Pruebas de Toxicidad/métodos , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/toxicidad , Bioensayo/métodos , Interacciones Hidrofóbicas e Hidrofílicas , Microfluídica/métodos , Compuestos Orgánicos/análisis , Manejo de Especímenes/métodos , Contaminantes Químicos del Agua/análisis

RESUMEN

In chronic toxicity tests with Caenorhabditis elegans, it is necessary to feed the nematode with bacteria, which reduces the freely dissolved concentration (Cfree) of hydrophobic organic chemicals (HOCs), leading to poorly defined exposure with conventional dosing procedures. We examined the efficacy of passive dosing of polycyclic aromatic hydrocarbons (PAHs) using silicone O-rings to control exposure during C. elegans toxicity testing and compared the results to those obtained with solvent spiking. Solid-phase microextraction and liquid-liquid extraction were used to measure Cfree and the chemicals taken up via ingestion. During toxicity testing, Cfree decreased by up to 89% after solvent spiking but remained constant with passive dosing. This led to a higher apparent toxicity on C. elegans exposed by passive dosing than by solvent spiking. With increasing bacterial cell densities, Cfree of solvent-spiked PAHs decreased while being maintained constant with passive dosing. This resulted in lower apparent toxicity under solvent spiking but an increased apparent toxicity with passive dosing, probably as a result of the higher chemical uptake rate via food (CUfood). Our results demonstrate the utility of passive dosing to control Cfree in routine chronic toxicity testing of HOCs. Moreover, both chemical uptake from water or via food ingestion can be controlled, thus enabling the discrimination of different uptake routes in chronic toxicity studies.

Asunto(s)

Caenorhabditis elegans , Pruebas de Toxicidad Crónica , Animales , Interacciones Hidrofóbicas e Hidrofílicas , Hidrocarburos Policíclicos Aromáticos , Pruebas de Toxicidad

RESUMEN

Mixtures of organic contaminants are ubiquitous in the environment. Depending on their persistence and physicochemical properties, individual chemicals that make up the mixture partition and distribute within the environment and might then jointly elicit toxicological effects. For the assessment and monitoring of such mixtures, a variety of cell-based in vitro and low-complexity in vivo bioassays based on algae, daphnids or fish embryos are available. A very important and sometimes unrecognized challenge is how to combine sampling, extraction and dosing to transfer the mixtures from the environment into bioassays, while conserving (or re-establishing) their chemical composition at adjustable levels for concentration-effect assessment. This article outlines various strategies for quantifiable transfer from environmental samples including water, sediment, and biota into bioassays using total extraction or polymer-based passive sampling combined with either solvent spiking or passive dosing.

Asunto(s)

Monitoreo del Ambiente , Contaminantes Químicos del Agua , Animales , Bioensayo

RESUMEN

We reviewed compliance monitoring requirements in the European Union, the United States, and the Oslo-Paris Convention for the protection of the marine environment of the North-East Atlantic, and evaluated if these are met by passive sampling methods for nonpolar compounds. The strengths and shortcomings of passive sampling are assessed for water, sediments, and biota. Passive water sampling is a suitable technique for measuring concentrations of freely dissolved compounds. This method yields results that are incompatible with the EU's quality standard definition in terms of total concentrations in water, but this definition has little scientific basis. Insufficient quality control is a present weakness of passive sampling in water. Laboratory performance studies and the development of standardized methods are needed to improve data quality and to encourage the use of passive sampling by commercial laboratories and monitoring agencies. Successful prediction of bioaccumulation based on passive sampling is well documented for organisms at the lower trophic levels, but requires more research for higher levels. Despite the existence of several knowledge gaps, passive sampling presently is the best available technology for chemical monitoring of nonpolar organic compounds. Key issues to be addressed by scientists and environmental managers are outlined.

Asunto(s)

Monitoreo del Ambiente/métodos , Compuestos Orgánicos/análisis , Contaminantes Químicos del Agua/análisis , Biota , Sedimentos Geológicos/química , Compuestos Orgánicos/química

RESUMEN

Equilibrium sampling can be applied to measure freely dissolved concentrations (cfree) of hydrophobic organic chemicals (HOCs) that are considered effective concentrations for diffusive uptake and partitioning. It can also yield concentrations in lipids at thermodynamic equilibrium with the sediment (clip⇌sed) by multiplying concentrations in the equilibrium sampling polymer with lipid to polymer partition coefficients. We have applied silicone coated glass jars for equilibrium sampling of seven 'indicator' polychlorinated biphenyls (PCBs) in sediment samples from ten locations along the River Elbe to measure cfree of PCBs and their clip⇌sed. For three sites, we then related clip⇌sed to lipid-normalized PCB concentrations (cbio,lip) that were determined independently by the German Environmental Specimen Bank in common bream, a fish species living in close contact with the sediment: (1) In all cases, cbio,lip were below clip⇌sed, (2) there was proportionality between the two parameters with high R(2) values (0.92-1.00) and (3) the slopes of the linear regressions were very similar between the three stations (0.297; 0.327; 0.390). These results confirm the close link between PCB bioaccumulation and the thermodynamic potential of sediment-associated HOCs for partitioning into lipids. This novel approach gives clearer and more consistent results compared to conventional approaches that are based on total concentrations in sediment and biota-sediment accumulation factors. We propose to apply equilibrium sampling for determining bioavailability and bioaccumulation potential of HOCs, since this technique can provide a thermodynamic basis for the risk assessment and management of contaminated sediments.

Asunto(s)

Monitoreo del Ambiente/métodos , Peces/metabolismo , Sedimentos Geológicos/química , Bifenilos Policlorados/metabolismo , Ríos/química , Contaminantes Químicos del Agua/metabolismo , Animales , Biota , Metabolismo de los Lípidos

RESUMEN

Bioaccumulation, the accumulation of a chemical in an organism relative to its level in the ambient medium, is of major environmental concern. Thus, monitoring chemical concentrations in biota are widely and increasingly used for assessing the chemical status of aquatic ecosystems. In this paper, various scientific and regulatory aspects of bioaccumulation in aquatic systems and the relevant critical issues are discussed. Monitoring chemical concentrations in biota can be used for compliance checking with regulatory directives, for identification of chemical sources or event-related environmental risk assessment. Assessing bioaccumulation in the field is challenging since many factors have to be considered that can affect the accumulation of a chemical in an organism. Passive sampling can complement biota monitoring since samplers with standardised partition properties can be used over a wide temporal and geographical range. Bioaccumulation is also assessed for regulation of chemicals of environmental concern whereby mainly data from laboratory studies on fish bioaccumulation are used. Field data can, however, provide additional important information for regulators. Strategies for bioaccumulation assessment still need to be harmonised for different regulations and groups of chemicals. To create awareness for critical issues and to mutually benefit from technical expertise and scientific findings, communication between risk assessment and monitoring communities needs to be improved. Scientists can support the establishment of new monitoring programs for bioaccumulation, e.g. in the frame of the amended European Environmental Quality Standard Directive.

RESUMEN

Oxyphil cell transformation of epithelial cells due to the accumulation of mitochondria occurs often during cellular aging. To understand the pathogenic mechanisms, we studied mitochondrial DNA (mtDNA) alterations in the three cell types of the parathyroids using multiplex real-time PCR and next-generation sequencing. mtDNA was analyzed from cytochrome c oxidase (COX)-positive and COX-negative areas of 19 parathyroids. Mitochondria-rich pre-oxyphil/oxyphil cells were more prone to develop COX defects than the mitochondria-poor clear chief cells (P < 0.001). mtDNA increased approximately 2.5-fold from clear chief to oxyphil cells. In COX deficiency, the increase was even more pronounced, and COX-negative oxyphil cells had approximately two times more mtDNA than COX-positive oxyphil cells (P < 0.001), illustrating the influence of COX deficiency on mtDNA biosynthesis, probably as a consequence of insufficient ATP synthesis. Next-generation sequencing revealed a broad spectrum of putative pathogenic mtDNA point mutations affecting NADH dehydrogenase and COX genes as well as regulatory elements of mtDNA. NADH dehydrogenase gene mutations preferentially accumulated in COX-positive pre-oxyphil/oxyphil cells and, therefore, could be essential for inducing oxyphil cell transformation by increasing mtDNA/mitochondrial biogenesis. In contrast, COX-negative cells predominantly harbored mutations in the MT-CO1 and MT-CO3 genes and in regulatory mtDNA elements, but only rarely NADH dehydrogenase mutations. Thus, multiple hits in NADH dehydrogenase and COX activity-impairing genes represent the molecular basis of oxyphil cell transformation in the parathyroids.

Asunto(s)

ADN Mitocondrial/genética , Complejo IV de Transporte de Electrones/genética , NADH Deshidrogenasa/genética , Células Oxífilas/patología , Enfermedades de las Paratiroides/patología , Glándulas Paratiroides/patología , Adulto , Anciano , Anciano de 80 o más Años , Senescencia Celular/genética , ADN Mitocondrial/metabolismo , Complejo IV de Transporte de Electrones/metabolismo , Humanos , Metaplasia/genética , Metaplasia/metabolismo , Persona de Mediana Edad , Mutación , NADH Deshidrogenasa/metabolismo , Células Oxífilas/metabolismo , Enfermedades de las Paratiroides/genética , Enfermedades de las Paratiroides/metabolismo , Glándulas Paratiroides/metabolismo

RESUMEN

Maintenance and maturation of primordial germ cells is controlled by complex genetic and epigenetic cascades, and disturbances in this network lead to either infertility or malignant aberration. Transcription factor TFAP2C has been described to be essential for primordial germ cell maintenance and to be upregulated in several human germ cell cancers. Using global gene expression profiling, we identified genes deregulated upon loss of Tfap2c in embryonic stem cells and primordial germ cell-like cells. We show that loss of Tfap2c affects many aspects of the genetic network regulating germ cell biology, such as downregulation of maturation markers and induction of markers indicative for somatic differentiation, cell cycle, epigenetic remodeling and pluripotency. Chromatin-immunoprecipitation analyses demonstrated binding of TFAP2C to regulatory regions of deregulated genes (Sfrp1, Dmrt1, Nanos3, c-Kit, Cdk6, Cdkn1a, Fgf4, Klf4, Dnmt3b and Dnmt3l) suggesting that these genes are direct transcriptional targets of TFAP2C in primordial germ cells. Since Tfap2c deficient primordial germ cell-like cells display cancer related deregulations in epigenetic remodeling, cell cycle and pluripotency control, the Tfap2c-knockout allele was bred onto 129S2/Sv genetic background. There, mice heterozygous for Tfap2c develop with high incidence germ cell cancer resembling human pediatric germ cell tumors. Precursor lesions can be observed as early as E16.5 in developing testes displaying persisting expression of pluripotency markers. We further demonstrate that mice with a heterozygous deletion of the TFAP2C target gene Nanos3 are also prone to develop teratomas. These data highlight TFAP2C as a critical and dose-sensitive regulator of germ cell fate.

Asunto(s)

Predisposición Genética a la Enfermedad , Células Germinativas/metabolismo , Haploinsuficiencia , Teratoma/genética , Teratoma/metabolismo , Factor de Transcripción AP-2/metabolismo , Animales , Diferenciación Celular/genética , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Inmunoprecipitación de Cromatina , Análisis por Conglomerados , Células Madre Embrionarias , Eliminación de Gen , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Células Germinativas/citología , Células Germinativas/patología , Heterocigoto , Factor 4 Similar a Kruppel , Masculino , Ratones , Ratones Noqueados , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Reproducibilidad de los Resultados , Teratoma/patología , Factor de Transcripción AP-2/deficiencia , Factor de Transcripción AP-2/genética , Activación Transcripcional

RESUMEN

C/EBPß (CCAAT enhancer binding protein) is a transcription factor that plays a crucial role in survival and transformation of ALK+ anaplastic large cell lymphoma (ALCL). The aim of this study was to identify the downstream targets of C/EBPß responsible for ALK-mediated oncogenesis. C/EBPß was knocked down in ALK+ ALCL cell lines with a C/EBPß-shRNA, followed by gene expression profiling (GEP). GEP analysis revealed a reproducible signature of genes that were significantly regulated by C/EBPß. Classification into biological categories revealed overrepresentation of genes involved in the immune response, apoptosis and cell proliferation. Transcriptional regulation by C/EBPß was found in 6 of 11 (BCL2A1, G0S2, TRIB1, S100A9, DDX21 and DDIT4) genes investigated by chromatin immunoprecipitation. We demonstrated that BCL2A1, G0S2 and DDX21 play a crucial role in survival and proliferation of ALK+ ALCL cells. DDX21, a gene involved in rRNA biogenesis, was found differentially overexpressed in primary ALK+ ALCL cases. All three candidate genes were validated in primary ALCL cases by either immunohistochemistry or RT-qPCR. In conclusion, we identified and validated several key C/EBPß-regulated genes with major impact on survival and cell growth in ALK+ ALCL, supporting the central role of C/EBPß in ALK-mediated oncogenesis.

Asunto(s)

Proteína beta Potenciadora de Unión a CCAAT/genética , Proteínas de Ciclo Celular/genética , ARN Helicasas DEAD-box/genética , Regulación Neoplásica de la Expresión Génica , Linfoma Anaplásico de Células Grandes/genética , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteína beta Potenciadora de Unión a CCAAT/antagonistas & inhibidores , Proteína beta Potenciadora de Unión a CCAAT/metabolismo , Carcinogénesis/genética , Carcinogénesis/metabolismo , Carcinogénesis/patología , Proteínas de Ciclo Celular/metabolismo , Línea Celular Tumoral , Supervivencia Celular/genética , Inmunoprecipitación de Cromatina , ARN Helicasas DEAD-box/metabolismo , Perfilación de la Expresión Génica , Humanos , Linfoma Anaplásico de Células Grandes/metabolismo , Linfoma Anaplásico de Células Grandes/patología , Antígenos de Histocompatibilidad Menor , Regiones Promotoras Genéticas , Unión Proteica , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Transducción de Señal , Transcripción Genética

RESUMEN

Female and male individuals of the same species often differ with respect to their susceptibility to toxicant stress. In the present study, sea urchins (Psammechinus miliaris) of both sexes were exposed to high (150 µg L⁻¹) and environmentally relevant (5 µg L⁻¹) concentrations of phenanthrene over 10 days. While food intake was significantly decreased following exposure to 150 µg L⁻¹ phenanthrene, histological indices (lipofuscin accumulation, fibrosis, oocyte atresia), energetic status (energy charge, sum adenylates, AMP/ATP ratio) as well as ascorbate levels in the gonads showed either little or no effect upon phenanthrene exposure. However, most parameters (vitamin C, energy charge, sum adenylates, AMP/ATP ratio, ATP and ADP concentrations, lipofuscin content, fibrosis) significantly differed between male and female animals. This study illustrates the difficulties to identify toxic injury in reproductive tissue as it may be superimposed by gametogenesis and spawning of gametes.

Asunto(s)

Gónadas/efectos de los fármacos , Fenantrenos/toxicidad , Erizos de Mar/efectos de los fármacos , Contaminantes Químicos del Agua/toxicidad , Adenosina Difosfato/metabolismo , Animales , Ácido Ascórbico/metabolismo , Conducta Animal/efectos de los fármacos , Biomarcadores/metabolismo , Relación Dosis-Respuesta a Droga , Metabolismo Energético/efectos de los fármacos , Conducta Alimentaria/efectos de los fármacos , Femenino , Gónadas/anatomía & histología , Gónadas/fisiología , Crecimiento y Desarrollo/efectos de los fármacos , Masculino , Fenantrenos/metabolismo , Erizos de Mar/anatomía & histología , Erizos de Mar/fisiología , Factores Sexuales , Estrés Fisiológico , Contaminantes Químicos del Agua/metabolismo

RESUMEN

BACKGROUND: Activator protein-2 (AP-2) transcription factors are critically involved in a variety of fundamental cellular processes such as proliferation, differentiation and apoptosis and have also been implicated in carcinogenesis. Expression of the family members AP-2alpha and AP-2gamma is particularly well documented in malignancies of the female breast. Despite increasing evaluation of single AP-2 isoforms in mammary tumors the functional role of concerted expression of multiple AP-2 isoforms in breast cancer remains to be elucidated. AP-2 proteins can form homo- or heterodimers, and there is growing evidence that the net effect whether a cell will proliferate, undergo apoptosis or differentiate is partly dependent on the balance between different AP-2 isoforms. METHODS: We simultaneously interfered with all AP-2 isoforms expressed in ErbB-2-positive murine N202.1A breast cancer cells by conditionally over-expressing a dominant-negative AP-2 mutant. RESULTS: We show that interference with AP-2 protein function lead to reduced cell number, induced apoptosis and increased chemo- and radiation-sensitivity. Analysis of global gene expression changes upon interference with AP-2 proteins identified 139 modulated genes (90 up-regulated, 49 down-regulated) compared with control cells. Gene Ontology (GO) investigations for these genes revealed Cell Death and Cell Adhesion and Migration as the main functional categories including 25 and 12 genes, respectively. By using information obtained from Ingenuity Pathway Analysis Systems we were able to present proven or potential connections between AP-2 regulated genes involved in cell death and response to chemo- and radiation therapy, (i.e. Ctgf, Nrp1, Tnfaip3, Gsta3) and AP-2 and other main apoptosis players and to create a unique network. CONCLUSIONS: Expression of AP-2 transcription factors in breast cancer cells supports proliferation and contributes to chemo- and radiation-resistance of tumor cells by impairing the ability to induce apoptosis. Therefore, interference with AP-2 function could increase the sensitivity of tumor cells towards therapeutic intervention.

Asunto(s)

Apoptosis , Resistencia a Antineoplásicos , Neoplasias Mamarias Experimentales/metabolismo , Tolerancia a Radiación , Factor de Transcripción AP-2/metabolismo , Animales , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Apoptosis/efectos de la radiación , Línea Celular Tumoral , Bases de Datos Genéticas , Femenino , Perfilación de la Expresión Génica/métodos , Regulación Neoplásica de la Expresión Génica , Redes Reguladoras de Genes , Neoplasias Mamarias Experimentales/genética , Neoplasias Mamarias Experimentales/patología , Ratones , Mutación , Análisis de Secuencia por Matrices de Oligonucleótidos , Isoformas de Proteínas , Receptor ErbB-2/metabolismo , Factor de Transcripción AP-2/genética , Transfección

RESUMEN

Extensive development of the mammary gland occurs during puberty, when rising levels of ovarian hormones induce the formation of highly proliferative terminal end buds (TEBs) at the tips of mammary ducts. TEBs consist of an outer layer of cap cells and of inner body cells. TEBs invade the adipose stroma and bifurcate while extending the ducts to generate an arborized ductal network. We show that in murine mammary glands transcription factor AP-2gamma is strongly expressed in the cap cell layer and in a subset of body cells of TEBs. To decipher AP-2gamma functions during mammary development we generated AP-2gamma-deficient mice. Their mammary glands displayed impaired ductal branching and elongation. Cellular proliferation within TEBs was reduced. Although estrogen receptor was expressed, exogenously administered ovarian hormones could not restore normal development. Therefore, AP-2gamma is functionally involved in branching morphogenesis of the mammary epithelium, possibly by controlling genetic processes downstream of ovarian hormones.

Asunto(s)

Regulación del Desarrollo de la Expresión Génica , Glándulas Mamarias Animales/crecimiento & desarrollo , Glándulas Mamarias Animales/metabolismo , Morfogénesis , Ovario/crecimiento & desarrollo , Factor de Transcripción AP-2/biosíntesis , Animales , Proliferación Celular , Femenino , Genotipo , Ratones , Ratones Noqueados , Ratones Transgénicos , Ovario/metabolismo , Fenotipo , Receptores de Estrógenos/metabolismo , Factores de Transcripción/metabolismo