RESUMEN
The genetics of relapsed pediatric acute myeloid leukemia (AML) has yet to be comprehensively defined. Here, we present the spectrum of genomic alterations in 136 relapsed pediatric AMLs. We identified recurrent exon 13 tandem duplications (TD) in upstream binding transcription factor (UBTF) in 9% of relapsed AML cases. UBTF-TD AMLs commonly have normal karyotype or trisomy 8 with cooccurring WT1 mutations or FLT3-ITD but not other known oncogenic fusions. These UBTF-TD events are stable during disease progression and are present in the founding clone. In addition, we observed that UBTF-TD AMLs account for approximately 4% of all de novo pediatric AMLs, are less common in adults, and are associated with poor outcomes and MRD positivity. Expression of UBTF-TD in primary hematopoietic cells is sufficient to enhance serial clonogenic activity and to drive a similar transcriptional program to UBTF-TD AMLs. Collectively, these clinical, genomic, and functional data establish UBTF-TD as a new recurrent mutation in AML. SIGNIFICANCE: We defined the spectrum of mutations in relapsed pediatric AML and identified UBTF-TDs as a new recurrent genetic alteration. These duplications are more common in children and define a group of AMLs with intermediate-risk cytogenetic abnormalities, FLT3-ITD and WT1 alterations, and are associated with poor outcomes. See related commentary by Hasserjian and Nardi, p. 173. This article is highlighted in the In This Issue feature, p. 171.
Asunto(s)
Leucemia Mieloide Aguda , Adulto , Niño , Aberraciones Cromosómicas , Exones , Genómica , Humanos , Leucemia Mieloide Aguda/genética , Mutación , RecurrenciaRESUMEN
Acute myeloid leukemia (AML) comprises a heterogeneous group of leukemias frequently defined by recurrent cytogenetic abnormalities, including rearrangements involving the core-binding factor (CBF) transcriptional complex. To better understand the genomic landscape of CBF-AMLs, we analyzed both pediatric (n = 87) and adult (n = 78) samples, including cases with RUNX1-RUNX1T1 (n = 85) or CBFB-MYH11 (n = 80) rearrangements, by whole-genome or whole-exome sequencing. In addition to known mutations in the Ras pathway, we identified recurrent stabilizing mutations in CCND2, suggesting a previously unappreciated cooperating pathway in CBF-AML. Outside of signaling alterations, RUNX1-RUNX1T1 and CBFB-MYH11 AMLs demonstrated remarkably different spectra of cooperating mutations, as RUNX1-RUNX1T1 cases harbored recurrent mutations in DHX15 and ZBTB7A, as well as an enrichment of mutations in epigenetic regulators, including ASXL2 and the cohesin complex. This detailed analysis provides insights into the pathogenesis and development of CBF-AML, while highlighting dramatic differences in the landscapes of cooperating mutations for these related AML subtypes.
Asunto(s)
Biomarcadores de Tumor/genética , Factores de Unión al Sitio Principal/genética , Genómica/métodos , Leucemia Mieloide Aguda/genética , Mutación/genética , Proteínas de Fusión Oncogénica/genética , Adulto , Niño , HumanosRESUMEN
Disruption of p53/Puma-mediated apoptosis protects against lethality due to DNA damage. Here we demonstrate the unexpected requirement of the pro-apoptotic p53-target gene Puma to mount a successful innate immune response to bacterial sepsis. Pumaâ»/â» mice rapidly died when challenged with bacteria. While the immune response in Pumaâ»/â» mice was unchanged in cell migration, phagocytosis and bacterial killing, sites of infection accumulated large abscesses and sepsis was progressive. Blocking p53/Puma-induced apoptosis during infection caused resistance to ROS-induced cell death in the CD49d+ neutrophil subpopulation, resulting in insufficient immune resolution. This study identifies a biological role for p53/Puma apoptosis in optimizing neutrophil lifespan so as to ensure the proper clearance of bacteria and exposes a counter-balance between the innate immune response to infection and survival from DNA damage.
Asunto(s)
Proteínas Reguladoras de la Apoptosis/inmunología , Genes p53 , Neutrófilos/inmunología , Sepsis/inmunología , Proteínas Supresoras de Tumor/inmunología , Animales , Apoptosis/inmunología , Proteínas Reguladoras de la Apoptosis/deficiencia , Proteínas Reguladoras de la Apoptosis/genética , Infecciones Bacterianas/inmunología , Supervivencia Celular/inmunología , Inmunidad Innata , Ratones , Ratones Noqueados , Proteínas Supresoras de Tumor/deficiencia , Proteínas Supresoras de Tumor/genéticaRESUMEN
Janus kinase 2 (Jak2) has a pivotal role in erythropoietin (Epo) signaling pathway, including erythrocyte differentiation and Stat5 activation. In the course of screening for critical phosphorylation of tyrosine residues in Jak2, we identified tyrosine 913 (Y(913)) as a novel and functional phosphorylation site, which negatively regulates Jak2. Phosphorylation at Y(913) rapidly occurred and was sustained for at least 120 min after Epo stimulation, in contrast to the transient phosphorylation of Y(1007/1008) in the activation loop of Jak2. Interestingly, phosphorylation defective mutation of Y(913) (Y(913)F) results in a significant enhancement of Epo-induced Jak2 activation, whereas phosphorylation mimic mutation of Y(913) (Y(913)E) completely abrogated its activation. Furthermore, Jak2 deficient fetal liver cells expressing Y(913)F mutant generated many mature erythroid BFU-E and CFU-E colonies, while Y(913)E mutant failed to reconstitute Jak2 deficiency. We also demonstrate, in Jak1, phosphorylation of Y(939), a corresponding tyrosine residue with Y(913), negatively regulated Jak1 signaling pathway. Accordingly, our results suggest that this tyrosine phosphorylation in JH1 domain may be involved in common negative regulation mechanism for Jak family.
Asunto(s)
Eritropoyetina/metabolismo , Janus Quinasa 2/metabolismo , Fosfotirosina/metabolismo , Transducción de Señal/efectos de los fármacos , Animales , Ensayo de Unidades Formadoras de Colonias , Secuencia Conservada , Activación Enzimática/efectos de los fármacos , Células Eritroides/citología , Células Eritroides/efectos de los fármacos , Eritropoyetina/farmacología , Interferón gamma/farmacología , Janus Quinasa 2/química , Ratones , Mutación/genética , Fosforilación/efectos de los fármacosRESUMEN
Suppressor of cytokine signaling 3 (SOCS3) inhibits leukemia-inhibitory factor (LIF) signaling and acts as a negative regulator. Deletion of SOCS3 causes embryonic lethality because of placental failure, and genetic reduction of LIF or the LIF receptor (LIFR) in SOCS3-deficient mice rescues placental defects and embryonic lethality; this indicates that SOCS3 is an essential inhibitor of LIFR signaling. However, the downstream signaling molecule that acts as a link between the LIFR and SOCS3 has not been identified. In this study we explored the downstream signaling of LIFR. The administration of LIF to SOCS3-heterozygous pregnant mice promotes trophoblast giant cell differentiation and accelerates placental failure in SOCS3-deficient mice. SOCS3-deficient trophoblast stem cells show enhanced and prolonged signal transducer and activator of transcription 3 (Stat3) activation by LIF stimulation. Further, in the trophoblasts of SOCS3-deficient placenta and differentiating cells from the choriocarcinoma-derived cell line Rcho-1 cells, constitutive activation of Stat3 is observed. The forced expression of SOCS3, dominant-negative Stat3, and dominant-negative Janus kinase 1 (JAK1) in Rcho-1 cells significantly suppressed the trophoblast giant cell differentiation of these cells. In addition, the number of trophoblast giant cells is significantly reduced concomitant with an increased number of precursor trophoblasts in JAK1-deficient placentas. Finally, JAK1 deficiency rescues placental defects and embryonic lethality in SOCS3-deficient mice. These results indicate that the LIFR signaling is finely coordinated by JAK1, Stat3, and SOCS3 and regulates trophoblast giant cell differentiation. In addition, these data establish that LIFR-JAK1-Stat3-SOCS3 signaling is an essential pathway for the regulation of trophoblast giant cell differentiation.
Asunto(s)
Células Gigantes/citología , Janus Quinasa 1/metabolismo , Factor Inhibidor de Leucemia/metabolismo , Factor de Transcripción STAT3/metabolismo , Proteínas Supresoras de la Señalización de Citocinas/metabolismo , Trofoblastos/citología , Animales , Diferenciación Celular , Cruzamientos Genéticos , Genes Dominantes , Heterocigoto , Ratones , Microscopía Fluorescente , Ratas , Transducción de Señal , Proteína 3 Supresora de la Señalización de Citocinas , Trofoblastos/metabolismoRESUMEN
Cytokines affect a variety of cellular functions, including regulation of cell numbers by suppression of programmed cell death. Suppression of apoptosis requires receptor signalling through the activation of Janus kinases and the subsequent regulation of members of the B-cell lymphoma 2 (Bcl-2) family. Here we demonstrate that a Bcl-2-family-related protein, Hax1, is required to suppress apoptosis in lymphocytes and neurons. Suppression requires the interaction of Hax1 with the mitochondrial proteases Parl (presenilin-associated, rhomboid-like) and HtrA2 (high-temperature-regulated A2, also known as Omi). These interactions allow Hax1 to present HtrA2 to Parl, and thereby facilitates the processing of HtrA2 to the active protease localized in the mitochondrial intermembrane space. In mouse lymphocytes, the presence of processed HtrA2 prevents the accumulation of mitochondrial-outer-membrane-associated activated Bax, an event that initiates apoptosis. Together, the results identify a previously unknown sequence of interactions involving a Bcl-2-family-related protein and mitochondrial proteases in the ability to resist the induction of apoptosis when cytokines are limiting.
Asunto(s)
Metaloproteasas/metabolismo , Proteínas Mitocondriales/metabolismo , Procesamiento Proteico-Postraduccional , Proteínas/metabolismo , Serina Endopeptidasas/metabolismo , Animales , Apoptosis , Supervivencia Celular , Genes Letales , Serina Peptidasa A2 que Requiere Temperaturas Altas , Péptidos y Proteínas de Señalización Intracelular , Linfocitos/citología , Linfocitos/metabolismo , Metaloproteasas/deficiencia , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Mitocondriales/química , Proteínas Mitocondriales/deficiencia , Neuronas/citología , Neuronas/metabolismo , Unión Proteica , Proteínas/genética , Serina Endopeptidasas/química , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Janus kinases are essential for signal transduction by a variety of cytokine receptors and when inappropriately activated can cause hematopoietic disorders and oncogenesis. Consequently, it can be predicted that the interaction of the kinases with receptors and the events required for activation are highly controlled. In a screen to identify phosphorylation events regulating Jak2 activity in EpoR signaling, we identified a mutant (Jak2-Y613E) which has the property of being constitutively activated, as well as an inactivating mutation (Y766E). Although no evidence was obtained to indicate that either site is phosphorylated in signaling, the consequences of the Y613E mutation are similar to those observed with recently described activating mutations in Jak2 (Jak2-V617F and Jak2-L611S). However, unlike the V617F or L611S mutant, the Y613E mutant requires the presence of the receptor but not Epo stimulation for activation and downstream signaling. The properties of the Jak2-Y613E mutant suggest that under normal conditions, Jak2 that is not associated with a receptor is locked into an inactive state and receptor binding through the FERM domain relieves steric constraints, allowing the potential to be activated with receptor engagement.
Asunto(s)
Janus Quinasa 2/metabolismo , Receptores de Eritropoyetina/fisiología , Sustitución de Aminoácidos , Animales , Línea Celular , Células Cultivadas , ADN Complementario , Embrión de Mamíferos , Activación Enzimática , Femenino , Fibroblastos/metabolismo , Humanos , Janus Quinasa 2/química , Janus Quinasa 2/genética , Riñón/citología , Modelos Biológicos , Fenilalanina/metabolismo , Fosforilación , Plásmidos , Embarazo , Estructura Terciaria de Proteína , Receptores de Eritropoyetina/genética , Receptores de Eritropoyetina/metabolismo , Retroviridae/genética , TransfecciónRESUMEN
The tyrosine kinase, Janus kinase-2 (Jak2), plays a pivotal role in signal transduction through a variety of cytokine receptors, including the receptor for erythropoietin (Epo). Although the physiological relevance of Jak2 has been definitively established, less is known about its regulation. In studies assessing the roles of sites of tyrosine phosphorylation, we identified Y(119) in the FERM (band 4.1, Ezrin, radixin and moesin) domain as a phosphorylation site. In these studies, we demonstrate that the phosphorylation of Y(119) in response to Epo downregulates Jak2 kinase activity. Using a phosphorylation mimic mutation (Y(119)E), downregulation is shown to involve dissociation of Jak2 from the receptor complex. Conversely, a Y(119)F mutant is more stably associated with the receptor complex. Thus, in cytokine responses, ligand binding induces activation of receptor associated Jak2, autophosphorylation of Y(119) in the FERM domain and the subsequent dissociation of the activated Jak2 from the receptor and degradation. This regulation occurs with the receptors for Epo, thrombopoietin and growth hormone but not with the receptor for interferon-gamma.
Asunto(s)
Janus Quinasa 2/metabolismo , Procesamiento Proteico-Postraduccional , Receptores de Citocinas/metabolismo , Transducción de Señal , Sustitución de Aminoácidos , Animales , Línea Celular , Citocinas/metabolismo , Humanos , Janus Quinasa 2/genética , Ligandos , Ratones , Ratones Transgénicos , Mutación Missense , Fosforilación , Unión Proteica/genética , Procesamiento Proteico-Postraduccional/genética , Estructura Terciaria de Proteína/genética , Receptores de Citocinas/agonistas , Transducción de Señal/genéticaRESUMEN
Mast cells are critical effectors of allergic disease, and are now implicated in immune responses observed in arthritis, multiple sclerosis, and heart disease. Because of their role in inflammation, understanding how mast cells develop is of clinical importance. In this study we determined the effects of IFN-gamma on mast cell survival. Using in vitro culture of bone marrow cells in IL-3 plus stem cell factor, we found that the addition of IFN-gamma induced apoptosis, as exhibited by the presence of subdiploid DNA and caspase activation. IFN-gamma-mediated apoptosis was Stat1-dependent, and was accompanied by loss of mitochondrial membrane potential. Apoptosis was reduced in cultures of bone marrow cells derived from p53- or Bax-deficient mice, as well as H2K-Bcl-2 transgenic mice. IFN-gamma hyperresponsiveness has been shown to result in inflammatory disease and death in mice lacking the regulatory protein suppressor of cytokine signaling (SOCS)-1. Bone marrow cells from SOCS-1 knockout (KO) mice failed to give rise to viable mast cells after culture in IL-3 plus stem cell factor, with profound apoptosis occurring as the cultures matured. However, bone marrow cells lacking both SOCS-1 and IFN-gamma survived normally. This in vitro defect in mast cell development was recapitulated in vivo. SOCS-1 KO mice demonstrated a 67% decrease in peritoneal mast cell numbers relative to wild-type mice, a deficiency that was reversed in SOCS-1/IFN-gamma KO mice. These data demonstrate the potent regulatory effects of IFN-gamma on mast cell survival and show that this cytokine can elicit mast cell death in vitro and in vivo.
Asunto(s)
Apoptosis/efectos de los fármacos , Interferón gamma/farmacología , Mastocitos/efectos de los fármacos , Animales , Proteínas Portadoras/fisiología , Recuento de Células , Proteínas de Unión al ADN/fisiología , Mastocitos/citología , Ratones , Ratones Noqueados , Mitocondrias/fisiología , Proteínas Proto-Oncogénicas c-kit/análisis , Proteínas Represoras/fisiología , Factor de Transcripción STAT1 , Proteína 1 Supresora de la Señalización de Citocinas , Proteínas Supresoras de la Señalización de Citocinas , Transactivadores/fisiologíaRESUMEN
Rearrangement of immunoglobulin heavy-chain variable (V(H)) gene segments has been suggested to be regulated by interleukin 7 signaling in pro-B cells. However, the genetic evidence for this recombination pathway has been challenged. Furthermore, no molecular components that directly control V(H) gene rearrangement have been elucidated. Using mice deficient in the interleukin 7-activated transcription factor STAT5, we demonstrate here that STAT5 regulated germline transcription, histone acetylation and DNA recombination of distal V(H) gene segments. STAT5 associated with V(H) gene segments in vivo and was recruited as a coactivator with the transcription factor Oct-1. STAT5 did not affect the nuclear repositioning or compaction of the immunoglobulin heavy-chain locus. Therefore, STAT5 functions at a distinct step in regulating distal V(H) recombination in relation to the transcription factor Pax5 and histone methyltransferase Ezh2.
Asunto(s)
Proteínas de Unión al ADN/metabolismo , Reordenamiento Génico , Cadenas Pesadas de Inmunoglobulina/metabolismo , Región Variable de Inmunoglobulina , Interleucina-7/genética , Interleucina-7/fisiología , Proteínas de la Leche/metabolismo , Transactivadores/metabolismo , Transcripción Genética , Animales , Linfocitos B/inmunología , Núcleo Celular/metabolismo , Cromatina/metabolismo , Inmunoprecipitación de Cromatina , Proteína Potenciadora del Homólogo Zeste 2 , N-Metiltransferasa de Histona-Lisina , Histonas/metabolismo , Inmunoprecipitación , Hibridación Fluorescente in Situ , Ratones , Ratones Transgénicos , Microscopía Fluorescente , Factor 1 de Transcripción de Unión a Octámeros , Oligonucleótidos/química , Factor de Transcripción PAX5 , Complejo Represivo Polycomb 2 , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas , Proteínas/metabolismo , ARN Mensajero/metabolismo , Recombinación Genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factor de Transcripción STAT5 , Células Madre/citología , Factores de Transcripción/metabolismoRESUMEN
The Evi-1 gene was first identified as a site for viral integration in murine myeloid leukemia. Evi-1 is a zinc finger transcription factor that has been implicated in the development of myeloid neoplasia. In humans, disruption of the Evi-1 locus, by chromosomal rearrangements, is associated with myeloid leukemia and myelodyplastic syndromes. Here, we report the cloning and developmental pattern of expression of Xenopus Evi-1. xEvi-1 is expressed during oogenesis and during embryonic development. In situ hydridization reveals that xEvi-1 has a dynamic expression profile during early embryonic development. Expression of Evi-1 is detected by in situ hybridization in the pronephric tissue, the brain and in neural crest derivatives of the head and neck.
Asunto(s)
Proteínas de Unión al ADN/biosíntesis , Regulación del Desarrollo de la Expresión Génica , Factores de Transcripción/biosíntesis , Secuencia de Aminoácidos , Animales , Northern Blotting , Encéfalo/metabolismo , Clonación Molecular , ADN Complementario/metabolismo , Biblioteca de Genes , Hibridación in Situ , Riñón/embriología , Proteína del Locus del Complejo MDS1 y EV11 , Ratones , Datos de Secuencia Molecular , Cresta Neural/metabolismo , Oocitos/metabolismo , Poli A/química , Proto-Oncogenes , Homología de Secuencia de Aminoácido , Factores de Tiempo , Transcripción Genética , Xenopus laevisRESUMEN
Suppressor of cytokine signaling 1 (SOCS1) is an obligate negative regulator of cytokine signaling and most importantly in vivo, signaling via the interferon-gamma (IFN-gamma) receptor. SOCS1, via its Src homology 2 domain, binds to phosphotyrosine residues in its targets, reducing the amplitude of signaling from cytokine receptors. SOCS1 is also implicated in blocking Toll-like receptor (TLR) signaling in macrophages activated by TLR agonists such as lipopolysaccharide (LPS), thus regulating multiple steps in the activation of innate immune responses. To rigorously test this, we isolated macrophages from Socs1-/- mice on multiple genetic backgrounds. We found no evidence that SOCS1 blocked TLR-activated pathways, endotoxin tolerance, or nitric oxide production. However, Socs1-/-;IFN-gamma-/- mice were extremely susceptible to LPS challenge, confirming previous findings. Because LPS induces IFN-beta production from macrophages, we tested whether SOCS1 regulates IFN-alpha/beta receptor signaling. We find that SOCS1 is required to inhibit IFN-alpha/beta receptor signaling in vitro. Furthermore, the absence of a single allele encoding TYK2, a JAK (Janus kinase) family member essential IFN-alpha/beta receptor signaling, rescued Socs1-/- mice from early lethality, even in the presence of IFN-gamma. We conclude that previous reports linking SOCS1 to TLR signaling are most likely due to effects on IFN-alpha/beta receptor signaling.
Asunto(s)
Proteínas Portadoras/fisiología , Glicoproteínas de Membrana/fisiología , Receptores de Superficie Celular/fisiología , Proteínas Represoras/fisiología , Transducción de Señal/fisiología , Animales , Proteínas Portadoras/genética , Proteínas de Unión al ADN/metabolismo , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Proteínas I-kappa B/metabolismo , Interferón gamma/deficiencia , Interferón gamma/genética , Interferón gamma/fisiología , Lipopolisacáridos/farmacología , Activación de Macrófagos/efectos de los fármacos , Macrófagos/efectos de los fármacos , Macrófagos/fisiología , Glicoproteínas de Membrana/agonistas , Proteínas de la Membrana , Ratones , Ratones Noqueados , Inhibidor NF-kappaB alfa , Fosforilación , Proteínas Tirosina Quinasas/deficiencia , Proteínas Tirosina Quinasas/genética , Proteínas Tirosina Quinasas/fisiología , Receptor de Interferón alfa y beta , Receptores de Superficie Celular/agonistas , Receptores de Interferón/antagonistas & inhibidores , Receptores de Interferón/fisiología , Proteínas Represoras/genética , Factor de Transcripción STAT1 , Proteína 1 Supresora de la Señalización de Citocinas , Proteínas Supresoras de la Señalización de Citocinas , TYK2 Quinasa , Receptores Toll-Like , Transactivadores/metabolismoRESUMEN
Puma encodes a BH3-only protein that is induced by the p53 tumor suppressor and other apoptotic stimuli. To assess its physiological role in apoptosis, we generated Puma knockout mice by gene targeting. Here we report that Puma is essential for hematopoietic cell death triggered by ionizing radiation (IR), deregulated c-Myc expression, and cytokine withdrawal. Puma is also required for IR-induced death throughout the developing nervous system and accounts for nearly all of the apoptotic activity attributed to p53 under these conditions. These findings establish Puma as a principal mediator of cell death in response to diverse apoptotic signals, implicating Puma as a likely tumor suppressor.
Asunto(s)
Apoptosis/fisiología , Proteínas Proto-Oncogénicas/metabolismo , Transducción de Señal/fisiología , Proteína p53 Supresora de Tumor/metabolismo , Animales , Apoptosis/efectos de la radiación , Proteínas Reguladoras de la Apoptosis , Citocinas/metabolismo , Ratones , Ratones Noqueados , Microscopía Fluorescente , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas c-myc/metabolismo , Radiación Ionizante , Linfocitos T/inmunología , Linfocitos T/metabolismo , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Suppressor of cytokine signaling (SOCS) proteins are feedback inhibitors of the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) signaling pathway. SOCS3 is upregulated by several signals in macrophages and has been implicated as a regulator of various signaling pathways. Here we show that phosphorylation of STAT3 is prolonged in mouse Socs3-deficient macrophages after stimulation with interleukin-6 (IL-6) but not IL-10, indicating that SOCS3 specifically affects signaling mediated by IL-6 and gp130. IL-6 induces a wider transcriptional response in Socs3-deficient macrophages than in wild-type cells; this response is dominated by interferon (IFN)-regulated genes owing to an excess of STAT1 phosphorylation. Thus, SOCS3 functions to control the quality of the response to IL-6 and prevents the activation of an IFN-induced program of gene expression.
Asunto(s)
Antígenos CD/inmunología , Glicoproteínas de Membrana/inmunología , Proteínas/inmunología , Proteínas Represoras , Factores de Transcripción , Animales , Antígenos CD/metabolismo , Receptor gp130 de Citocinas , Proteínas de Unión al ADN/inmunología , Proteínas de Unión al ADN/metabolismo , Femenino , Interferón gamma/inmunología , Interleucina-10/inmunología , Interleucina-6/inmunología , Macrófagos/inmunología , Macrófagos/metabolismo , Masculino , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Noqueados , Análisis de Secuencia por Matrices de Oligonucleótidos , Fosforilación , Factor de Transcripción STAT1 , Factor de Transcripción STAT3 , Transducción de Señal/inmunología , Proteína 3 Supresora de la Señalización de Citocinas , Proteínas Supresoras de la Señalización de Citocinas , Transactivadores/inmunología , Transactivadores/metabolismo , Dominios Homologos src/inmunologíaRESUMEN
Myc and E2f1 promote cell cycle progression, but overexpression of either can trigger p53-dependent apoptosis. Mice expressing an Emu-Myc transgene in B lymphocytes develop lymphomas, the majority of which sustain mutations of either the Arf or p53 tumor suppressors. Emu-Myc transgenic mice lacking one or both E2f1 alleles exhibited a slower onset of lymphoma development associated with increased expression of the cyclin-dependent kinase inhibitor p27(Kip1) and a reduced S phase fraction in precancerous B cells. In contrast, Myc-induced apoptosis and the frequency of Arf and p53 mutations in lymphomas were unaffected by E2f1 loss. Therefore, Myc does not require E2f1 to induce Arf, p53, or apoptosis in B cells, but depends upon E2f1 to accelerate cell cycle progression and downregulate p27(Kip1).
Asunto(s)
Apoptosis/genética , Proteínas de Ciclo Celular/metabolismo , División Celular/genética , Transformación Celular Neoplásica/metabolismo , Proteínas de Unión al ADN , Linfoma/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Factores de Transcripción/deficiencia , Factor 1 de Ribosilacion-ADP/genética , Factor 1 de Ribosilacion-ADP/metabolismo , Animales , Proteínas de Ciclo Celular/genética , Transformación Celular Neoplásica/genética , Inhibidor p27 de las Quinasas Dependientes de la Ciclina , Factores de Transcripción E2F , Factor de Transcripción E2F1 , Femenino , Genotipo , Linfoma/genética , Linfoma/fisiopatología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Mutación/genética , Proteínas Proto-Oncogénicas c-myc/genética , Fase S/genética , Factores de Transcripción/genética , Transgenes/genética , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismoRESUMEN
Suppressor of cytokine signaling 3 (SOCS3) binds cytokine receptors and thereby suppresses cytokine signaling. Deletion of SOCS3 causes an embryonic lethality that is rescued by a tetraploid rescue approach, demonstrating an essential role in placental development and a non-essential role in embryo development. Rescued SOCS3-deficient mice show a perinatal lethality with cardiac hypertrophy. SOCS3-deficient placentas have reduced spongiotrophoblasts and increased trophoblast secondary giant cells. Enforced expression of SOCS3 in a trophoblast stem cell line (Rcho-1) suppresses giant cell differentiation. Conversely, SOCS3-deficient trophoblast stem cells differentiate more readily to giant cells in culture, demonstrating that SOCS3 negatively regulates trophoblast giant cell differentiation. Leukemia inhibitory factor (LIF) promotes giant cell differentiation in vitro, and LIF receptor (LIFR) deficiency results in loss of giant cell differentiation in vivo. Finally, LIFR deficiency rescues the SOCS3-deficient placental defect and embryonic lethality. The results establish SOCS3 as an essential regulator of LIFR signaling in trophoblast differentiation.
Asunto(s)
Diferenciación Celular/fisiología , Proteínas/metabolismo , Receptores de Citocinas/metabolismo , Proteínas Represoras , Transducción de Señal/fisiología , Factores de Transcripción , Trofoblastos/metabolismo , Animales , Línea Celular , Linaje de la Célula , Embrión de Mamíferos/fisiología , Edad Gestacional , Hibridación in Situ , Subunidad alfa del Receptor del Factor Inhibidor de Leucemia , Ratones , Ratones Noqueados , Miocardio/patología , Placenta/citología , Placenta/metabolismo , Proteínas/genética , Receptores OSM-LIF , Células Madre/citología , Células Madre/metabolismo , Proteína 3 Supresora de la Señalización de Citocinas , Proteínas Supresoras de la Señalización de Citocinas , Tasa de Supervivencia , Distribución Tisular , Trofoblastos/citologíaRESUMEN
The identification of common virus integration sites (cVIS) in retrovirally induced tumors in mice provides a powerful strategy to isolate novel transforming genes. Applying virus LTR-specific inverse-PCR and RT-PCR combined with automated sequencing on CasBr-M Murine Leukemia Virus (MuLV) induced myeloid leukemias, 126 virus integration sites were cloned. Using locus- and LTR-specific primers, a nested-PCR/Southern-blotting procedure was developed on genomic DNA from a large panel of MuLV-induced leukemias, to analyse whether a particular virus insertion represented a cVIS. In fact 39 out of 41 integrations analysed this way appeared to represent a common virus integration. We recognized six previously cloned cVISs, i.e. Evi1, Hoxa7, c-Myb, Cb2/Evi11, Evi12, and His1 and 33 novel common insertions, designated Cas-Br Virus Integration Site (Casvis). Among this group we found integrations in or near genes encoding nuclear proteins, e.g. Dnmt-2, Nm23-M2, Ctbp1 or Erg, within receptor genes, e.g. Cb2 or mrc1, novel putative signaling or transporter genes, the ringfinger-protein gene Mid1 and a panel of genes encoding novel proteins with unknown function. The finding that 39 out of 41 integrations analysed represented a cVIS, suggests that the majority of the other virus insertions that were not yet analysed by the PCR/Southern-blotting method are located in a cVIS as well and may therefore also harbor novel disease genes.
Asunto(s)
Leucemia Mieloide/genética , Integración Viral , Animales , Southern Blotting , Clonación Molecular , Virus de la Leucemia Murina , Ratones , Mutagénesis Insercional , Reacción en Cadena de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Secuencias Repetidas Terminales , Células Tumorales CultivadasRESUMEN
Defining signals that can support the self-renewal of multipotential hemopoietic progenitor cells (MHPCs) is pertinent to understanding leukemogenesis and may be relevant to developing stem cell-based therapies. Here we define a set of signals, JAK2 plus either c-kit or flt-3, which together can support extensive MHPC self-renewal. Phenotypically and functionally distinct populations of MHPCs were obtained, depending on which receptor tyrosine kinase, c-kit or flt-3, was activated. Self-renewal was abrogated in the absence of STAT5a/b, and in the presence of inhibitors targeting either the mitogen-activated protein kinase or phosphatidylinositol 3' kinase pathways. These findings suggest that a simple two-component signal can drive MHPC self-renewal.