RESUMEN
TAZ (WWTR1) is a transcriptional co-activator regulated by Hippo signaling, mechano-transduction, and G-protein couple receptors. Once activated, TAZ and its paralogue, YAP1, regulate gene expression programs promoting cell proliferation, survival, and differentiation, thus controlling embryonic development, tissue regeneration, and aging. YAP and TAZ are also frequently activated in tumors, particularly in poorly differentiated and highly aggressive malignancies. Yet, mutations of YAP/TAZ or of their upstream regulators do not fully account for their activation in cancer, raising the possibility that other upstream regulatory pathways, still to be defined, are altered in tumors. In this work, we set out to identify novel regulators of TAZ by means of a siRNA-based screen. We identified 200 genes able to modulate the transcriptional activity of TAZ, with prominence for genes implicated in cell-cell contact, cytoskeletal tension, cell migration, WNT signaling, chromatin remodeling, and interleukins and NF-kappaB signaling. Among these genes we identified was BRCC3, a component of the BRCA1 complex that guards genome integrity and exerts tumor suppressive activity during cancer development. The loss of BRCC3 or BRCA1 leads to an increased level and activity of TAZ. Follow-up studies indicated that the cytoplasmic BRCA1 complex controls the ubiquitination and stability of TAZ. This may suggest that, in tumors, inactivating mutations of BRCA1 may unleash cell transformation by activating the TAZ oncogene.
Asunto(s)
Neoplasias , Transactivadores , Humanos , Transactivadores/genética , Transactivadores/metabolismo , Proteínas Señalizadoras YAP , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Vía de Señalización Wnt , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Enzimas Desubicuitinizantes/metabolismoRESUMEN
OBJECTIVE: To assess the overall effectiveness of anti-vascular endothelial growth factor (VEGF) therapy in treatment-naïve patients with neovascular age-related macular degeneration (nAMD) in a clinical practice setting. STUDY DESIGN: EAGLE was a retrospective, 2-year, cohort observational, multicenter study conducted in Italy that analyzed secondary data of treatment-naïve patients with nAMD. The primary endpoint evaluated the mean annualized number of anti-VEGF injections at Years 1 and 2. The main secondary endpoints analyzed the mean change in visual acuity (VA) from baseline and variables associated with visual outcomes at Years 1 and 2. RESULTS: Of the 752 patients enrolled, 745 (99.07%) received the first dose of anti-VEGF in 2016. Overall, 429 (57.05%) and 335 (44.5%) patients completed the 1- and 2-year follow-ups, respectively. At baseline, mean (standard deviation, SD) age was 75.6 (8.8) years and the mean (SD) VA was 53.43 (22.8) letters. The mean (SD) number of injections performed over the 2 years was 8.2 (4.1) resulting in a mean (SD) change in VA of 2.45 (19.36) (P = 0.0005) letters at Year 1 and -1.34 (20.85) (P = 0.3984) letters at Year 2. Linear regression models showed that age, baseline VA, number of injections, and early fluid resolution were the variables independently associated with visual outcomes at Years 1 and 2. CONCLUSIONS: The EAGLE study analyzed the routine clinical practice management of patients with nAMD in Italy. The study suggested that visual outcomes in clinical practice may be improved with earlier diagnosis, higher number of injections, and accurate fluid resolution targeting during treatment induction.
Asunto(s)
Inhibidores de la Angiogénesis/administración & dosificación , Degeneración Macular/tratamiento farmacológico , Neovascularización Retiniana/tratamiento farmacológico , Factor A de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Agudeza Visual/efectos de los fármacos , Anciano , Anciano de 80 o más Años , Esquema de Medicación , Femenino , Estudios de Seguimiento , Humanos , Inyecciones Intravítreas , Italia , Degeneración Macular/diagnóstico , Masculino , Neovascularización Retiniana/diagnóstico , Estudios Retrospectivos , Factores de Tiempo , Resultado del TratamientoRESUMEN
Mammalian cells must integrate environmental cues to determine coherent physiological responses. The transcription factors Myc and YAP-TEAD act downstream from mitogenic signals, with the latter responding also to mechanical cues. Here, we show that these factors coordinately regulate genes required for cell proliferation. Activation of Myc led to extensive association with its genomic targets, most of which were prebound by TEAD. At these loci, recruitment of YAP was Myc-dependent and led to full transcriptional activation. This cooperation was critical for cell cycle entry, organ growth, and tumorigenesis. Thus, Myc and YAP-TEAD integrate mitogenic and mechanical cues at the transcriptional level to provide multifactorial control of cell proliferation.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proliferación Celular/genética , Fosfoproteínas/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Activación Transcripcional , Proteínas Adaptadoras Transductoras de Señales/genética , Animales , Ciclo Celular/genética , Proteínas de Ciclo Celular , Células Cultivadas , Péptidos y Proteínas de Señalización Intercelular/fisiología , Mecanotransducción Celular , Ratones , Ratones Transgénicos , Fosfoproteínas/genética , Transducción de Señal , Factores de Transcripción/metabolismo , Proteínas Señalizadoras YAPRESUMEN
The state of modification of histone tails plays an important role in defining the accessibility of DNA for the transcription machinery and other regulatory factors. It has been extensively demonstrated that the posttranslational modifications of the histone tails, as well as modifications within the nucleosome domain, regulate the level of chromatin condensation and are therefore important in regulating gene expression and other nuclear events. Together with DNA methylation, they constitute the most relevant level of epigenetic regulation of cell functions. Histone modifications are carried out by a multipart network of macromolecular complexes endowed with enzymatic, regulatory, and recognition domains. Not surprisingly, epigenetic alterations caused by aberrant activity of these enzymes are linked to the establishment and maintenance of the cancer phenotype and, importantly, are potentially reversible, since they do not involve genetic mutations in the underlying DNA sequence. Histone modification therapy of cancer is based on the generation of drugs able to interfere with the activity of enzymes involved in histone modifications: new drugs have recently been approved for use in cancer patients, clinically validating this strategy. Unfortunately, however, clinical responses are not always consistent and do not parallel closely the results observed in preclinical models. Here, we present a brief overview of the deregulation of chromatin-associated enzymatic activities in cancer cells and of the main results achieved by histone modification therapeutic approaches.
Asunto(s)
Antineoplásicos/uso terapéutico , Inhibidores Enzimáticos/uso terapéutico , Epigénesis Genética/efectos de los fármacos , Histonas/metabolismo , Neoplasias/tratamiento farmacológico , Acetilación , Animales , Metilación de ADN , Histona Acetiltransferasas/antagonistas & inhibidores , Histona Acetiltransferasas/metabolismo , Inhibidores de Histona Desacetilasas/uso terapéutico , Histona Desacetilasas/metabolismo , Histona Demetilasas/antagonistas & inhibidores , Histona Demetilasas/metabolismo , Histona Metiltransferasas , N-Metiltransferasa de Histona-Lisina/antagonistas & inhibidores , N-Metiltransferasa de Histona-Lisina/metabolismo , Humanos , Péptidos y Proteínas de Señalización Intracelular , Metilación , Metiltransferasas/metabolismo , Neoplasias/metabolismo , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Proteína-Arginina N-MetiltransferasasRESUMEN
Spatial distribution of genes within the nucleus contributes to transcriptional control, allowing optimal gene expression as well as constitutive or regulated gene repression. Human immunodeficiency virus type 1 (HIV-1) integrates into host chromatin to transcribe and replicate its genome. Lymphocytes harbouring a quiescent but inducible provirus are a challenge to viral eradication in infected patients undergoing antiviral therapy. Therefore, our understanding of the contribution of sub-nuclear positioning to viral transcription may also have far-reaching implications in the pathology of the infection. To gain an insight into the conformation of chromatin at the site of HIV-1 integration, we investigated lymphocytes carrying a single latent provirus. In the silenced state, the provirus was consistently found at the nuclear periphery, associated in trans with a pericentromeric region of chromosome 12 in a significant number of quiescent cells. After induction of the transcription, this association was lost, although the location of the transcribing provirus remained peripheral. These results, extended to several other cell clones, unveil a novel mechanism of transcriptional silencing involved in HIV-1 post-transcriptional latency and reinforce the notion that gene transcription may also occur at the nuclear periphery.
Asunto(s)
Núcleo Celular/virología , Regulación Viral de la Expresión Génica , VIH-1/fisiología , Linfocitos/virología , Provirus/fisiología , Transcripción Genética , Activación Transcripcional , Centrómero/metabolismo , Centrómero/ultraestructura , Cromatina/metabolismo , Cromatina/ultraestructura , Humanos , Células Jurkat , Modelos BiológicosRESUMEN
BACKGROUND: The human immunodeficiency virus type 1 (HIV-1) favors integration in active genes of host chromatin. It is believed that transcriptional interference of the viral promoter over the endogenous gene or vice versa might occur with implications in HIV-1 post-integrative transcriptional latency. RESULTS: In this work a cell line has been transduced with a HIV-based vector and selected for Tat-inducible expression. These cells were found to carry a single silent integration in sense orientation within the second intron of the HMBOX1 gene. The HIV-1 Tat transactivator induced the viral LTR and repressed HMBOX1 expression independently of vector integration. Instead, single-cell quantitative in situ hybridization revealed that allele-specific transcription of HMBOX1 carrying the integrated provirus was not affected by the transactivation of the viral LTR in cis. CONCLUSION: A major observation of the work is that the HIV-1 genome has inserted in genes that are also repressed by Tat and this could be an advantage for the virus during transcriptional reactivation. In addition, it has also been observed that transcription of the provirus and of the endogenous gene in which it is integrated may coexist at the same time in the same genomic location.