Asunto(s)

Transformación Celular Neoplásica/genética , Proteínas de Unión al ADN/fisiología , Regulación Leucémica de la Expresión Génica , Leucemia/genética , Proteínas de Neoplasias/fisiología , Proteínas Proto-Oncogénicas , Proteínas Represoras , Factores de Transcripción/fisiología , Adulto , Secuencia de Aminoácidos , Niño , Cromosomas Humanos Par 12/genética , Cromosomas Humanos Par 12/ultraestructura , Clonación Molecular , Subunidad alfa 2 del Factor de Unión al Sitio Principal , Proteínas de Unión al ADN/genética , Eliminación de Gen , Genes abl , Secuencias Hélice-Asa-Hélice/genética , Humanos , Leucemia/patología , Leucemia Mielomonocítica Crónica/genética , Leucemia Mielomonocítica Crónica/patología , Modelos Genéticos , Datos de Secuencia Molecular , Proteínas de Neoplasias/genética , Proteínas de Fusión Oncogénica/genética , Proteínas de Fusión Oncogénica/fisiología , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/patología , Proteínas Proto-Oncogénicas c-ets , Receptor beta de Factor de Crecimiento Derivado de Plaquetas , Receptores del Factor de Crecimiento Derivado de Plaquetas/genética , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Factores de Transcripción/genética , Translocación Genética , Proteína ETS de Variante de Translocación 6

RESUMEN

The TEL/PDGF beta R fusion protein is the product of the t(5;12) translocation in patients with chronic myelomonocytic leukemia. The TEL/PDGF beta R is an unusual fusion of a putative transcription factor, TEL, to a receptor tyrosine kinase. The translocation fuses the amino terminus of TEL, containing the helix-loop-helix (HLH) domain, to the transmembrane and cytoplasmic domain of the PDGF beta R. We hypothesized that TEL/PDGF beta R self-association, mediated by the HLH domain of TEL, would lead to constitutive activation of the PDGF beta R tyrosine kinase domain and cellular transformation. Analysis of in vitro-translated TEL/ PDGF beta R confirmed that the protein self-associated and that self-association was abrogated by deletion of 51 aa within the TEL HLH domain. In vivo, TEL/PDGF beta R was detected as a 100-kDa protein that was constitutively phosphorylated on tyrosine and transformed the murine hematopoietic cell line Ba/F3 to interleukin 3 growth factor independence. Transformation of Ba/F3 cells required the HLH domain of TEL and the kinase activity of the PDGF beta R portion of the fusion protein. Immunoblotting demonstrated that TEL/PDGF beta R associated with multiple signaling molecules known to associate with the activated PDGF beta R, including phospholipase C gamma 1, SHP2, and phosphoinositol-3-kinase. TEL/PDGF beta R is a novel transforming protein that self-associates and activates PDGF beta R-dependent signaling pathways. Oligomerization of TEL/PDGF beta R that is dependent on the TEL HLH domain provides further evidence that the HLH domain, highly conserved among ETS family members, is a self-association motif.

Asunto(s)

Proteínas de Unión al ADN/metabolismo , Leucemia Mielomonocítica Crónica/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Receptores del Factor de Crecimiento Derivado de Plaquetas/metabolismo , Proteínas Represoras , Transducción de Señal , Factores de Transcripción/metabolismo , Proteínas de Unión al ADN/genética , Humanos , Leucemia Mielomonocítica Crónica/genética , Datos de Secuencia Molecular , Proteínas de Neoplasias/genética , Proteínas Proto-Oncogénicas c-ets , Receptor beta de Factor de Crecimiento Derivado de Plaquetas , Factores de Transcripción/genética , Translocación Genética , Proteína ETS de Variante de Translocación 6

RESUMEN

TEL is a member of the Ets family of transcription factors which are frequently rearranged in human leukemia. The mechanism of TEL-mediated transformation, however, is unknown. We report the cloning and characterization of a chromosomal translocation associated with acute myeloid leukemia which fuses TEL to the ABL tyrosine kinase. The TEL-ABL fusion confers growth factor-independent growth to the marine hematopoietic cell line Ba/F3 and transforms Rat-1 fibroblasts and primary murine bone marrow cells. TEL-ABL is constitutively tyrosine phosphorylated and localizes to the cytoskeleton. A TEL-ABL mutant containing an ABL kinase-inactivating mutation is not constitutively phosphorylated and is nontransforming but retains cytoskeletal localization. However, constitutive phosphorylation, cytoskeletal localization, and transformation are all dependent upon a highly conserved region of TEL termed the helix-loop-helix (HLH) domain. TEL-ABL formed HLH-dependent homo-oligomers in vitro, a process critical for tyrosine kinase activation. These experiments suggest that oligomerization of TEL-ABL mediated by the TEL HLH domain is required for tyrosine kinase activation, cytoskeletal localization, and transformation. These data also suggest that oligomerization of Ets proteins through the highly conserved HLH domain may represent a previously unrecognized phenomenon.

Asunto(s)

Proteínas de Unión al ADN/metabolismo , Leucemia Mieloide/metabolismo , Proteínas Proto-Oncogénicas c-abl/metabolismo , Proteínas Represoras , Factores de Transcripción/metabolismo , Anciano , Anciano de 80 o más Años , Secuencia de Aminoácidos , Secuencia de Bases , Mapeo Cromosómico , Cromosomas Humanos Par 12 , Proteínas del Citoesqueleto/metabolismo , Cartilla de ADN/química , Regulación Neoplásica de la Expresión Génica , Secuencias Hélice-Asa-Hélice , Humanos , Masculino , Datos de Secuencia Molecular , Fosfoproteínas/metabolismo , Unión Proteica , Proteínas Proto-Oncogénicas c-ets , ARN Mensajero/genética , ARN Neoplásico/genética , Proteínas Recombinantes de Fusión , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Translocación Genética , Proteína ETS de Variante de Translocación 6

Asunto(s)

Proteínas de Unión al ADN/genética , Leucemia Mieloide/genética , Leucemia Mielomonocítica Crónica/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Proteínas Proto-Oncogénicas , Proteínas Represoras , Factores de Transcripción/genética , Transformación Celular Neoplásica , Cromosomas Humanos Par 12 , Cromosomas Humanos Par 21 , Cromosomas Humanos Par 5 , Cromosomas Humanos Par 9 , Subunidad alfa 2 del Factor de Unión al Sitio Principal , Humanos , Proteínas de Neoplasias/genética , Proteínas Proto-Oncogénicas c-ets , Receptores del Factor de Crecimiento Derivado de Plaquetas/genética , Translocación Genética , Proteína ETS de Variante de Translocación 6

RESUMEN

TEL is a new member of the ETS family of transcription factors which is rearranged in a number of hematologic malignancies with translocations involving chromosome band 12p13. In some cases, both TEL alleles are affected, resulting in loss of wild-type TEL function in the leukemic cells. In addition, 5% of children with acute lymphoblastic leukemia (ALL) have 12p12-p13 deletions, suggesting that a tumor suppressor gene resides on 12p. These observations led us to consider whether TEL loss of function may contribute to the pathogenesis of ALL. In this report we show that the TEL gene maps between the polymorphic markers D12S89 and D12S98, and we use these flanking markers to screen paired diagnosis and remission samples from 81 children with ALL for loss of heterozygosity (LOH) at the TEL gene locus. Fifteen percent of informative patients showed TEL LOH which was not evident on cytogenetic analysis. Detailed examination of patients with LOH at this locus showed that the critically deleted region included two candidate tumor suppressor genes: TEL and KIP1, the gene encoding the cyclin-dependent kinase inhibitor p27. These studies show that LOH at the TEL locus is a frequent finding in childhood ALL.

Asunto(s)

Proteínas de Ciclo Celular , Cromosomas Humanos Par 12 , Proteínas de Unión al ADN/metabolismo , Genes Supresores de Tumor , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Proteínas Represoras , Factores de Transcripción/metabolismo , Proteínas Supresoras de Tumor , Adolescente , Aneuploidia , Secuencia de Bases , Niño , Preescolar , Mapeo Cromosómico , Cromosomas Artificiales de Levadura , Cromosomas Humanos Par 12/ultraestructura , Inhibidor p27 de las Quinasas Dependientes de la Ciclina , Marcadores Genéticos , Humanos , Hibridación Fluorescente in Situ , Técnicas In Vitro , Lactante , Masculino , Proteínas Asociadas a Microtúbulos/deficiencia , Proteínas Asociadas a Microtúbulos/genética , Datos de Secuencia Molecular , Leucemia-Linfoma Linfoblástico de Células Precursoras/patología , Proteínas Proto-Oncogénicas c-ets , Eliminación de Secuencia , Factores de Transcripción/deficiencia , Translocación Genética , Proteína ETS de Variante de Translocación 6

RESUMEN

Chromosomal rearrangements involving band 12p13 are found in a wide variety of human leukemias but are particularly common in childhood acute lymphoblastic leukemia. The genes involved in these rearrangements, however, have not been identified. We now report the cloning of a t(12;21) translocation breakpoint involving 12p13 and 21q22 in two cases of childhood pre-B acute lymphoblastic leukemia, in which t(12;21) rearrangements were not initially apparent. The consequence of the translocation is fusion of the helix-loop-helix domain of TEL, an ETS-like putative transcription factor, to the DNA-binding and transactivation domains of the transcription factor AML1. These data show that TEL, previously shown to be fused to the platelet-derived growth factor receptor beta in chronic myelomonocytic leukemia, can be implicated in the pathogenesis of leukemia through its fusion to either a receptor tyrosine kinase or a transcription factor. The TEL-AML1 fusion also indicates that translocations affecting the AML1 gene can be associated with lymphoid, as well as myeloid, malignancy.

Asunto(s)

Cromosomas Humanos Par 12 , Cromosomas Humanos Par 21 , Clonación Molecular , Proteínas de Unión al ADN/genética , Reordenamiento Génico , Proteínas de Neoplasias/genética , Proteínas de Fusión Oncogénica , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Proteínas Proto-Oncogénicas , Proteínas Represoras , Factores de Transcripción/genética , Secuencia de Aminoácidos , Secuencia de Bases , Southern Blotting , Médula Ósea/patología , Preescolar , Mapeo Cromosómico , Subunidad alfa 2 del Factor de Unión al Sitio Principal , Cartilla de ADN , Secuencias Hélice-Asa-Hélice , Humanos , Cariotipificación , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Leucemia-Linfoma Linfoblástico de Células Precursoras/patología , Proteínas Proto-Oncogénicas c-ets , Proteína ETS de Variante de Translocación 6

RESUMEN

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic syndrome characterized by abnormal clonal myeloid proliferation and by progression to acute myelogenous leukemia (AML). CMML thus offers an opportunity to study early genetic events in the transition to AML. A recently recognized subgroup of CMML has a t(5;12)(q33;p13) balanced translocation. We report that the consequence of the t(5;12) translocation is expression of a fusion transcript in which the tyrosine kinase domain of the platelet-derived growth factor receptor beta (PDGFR beta) on chromosome 5 is coupled to a novel ets-like gene, tel, on chromosome 12. The tel-PDGFR beta fusion demonstrates the oncogenic potential of PDGFR beta and may provide a paradigm for early events in the pathogenesis of AML.

Asunto(s)

Cromosomas Humanos Par 12 , Cromosomas Humanos Par 5 , Proteínas de Unión al ADN/genética , Leucemia Mielomonocítica Crónica/genética , Receptores del Factor de Crecimiento Derivado de Plaquetas/genética , Proteínas Represoras , Factores de Transcripción/genética , Translocación Genética/genética , Secuencia de Aminoácidos , Secuencia de Bases , Transformación Celular Neoplásica , Mapeo Cromosómico , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/fisiología , Humanos , Cariotipificación , Leucemia Mieloide Aguda/genética , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Proteínas Proto-Oncogénicas c-ets , ARN Mensajero/análisis , Receptores del Factor de Crecimiento Derivado de Plaquetas/fisiología , Análisis de Secuencia de ADN , Factores de Transcripción/química , Factores de Transcripción/fisiología , Transcripción Genética , Proteína ETS de Variante de Translocación 6

RESUMEN

The intracellular accumulation of the unspliced RNA of Rous sarcoma virus was decreased when translation was prematurely terminated by the introduction of nonsense codons within its 5' proximal gene, the gag gene. Subcellular fractionation of transfected cells suggested that nonsense codon-mediated instability occurred in the cytoplasm. Analysis of constructs containing an in-frame deletion in the nucleocapsid domain of gag, which prevents interaction between the Gag protein and viral RNA, showed that an open reading frame extending to approximately 30 nucleotides from the natural gag termination codon was needed for RNA stability. Sequences at the gag-pol junction necessary for ribosomal frameshifting were not required for RNA stability; however, sequences located 100 to 200 nucleotides downstream of the natural gag termination codon were found to be necessary for stable RNA. The stability of RNAs lacking this downstream sequence was not markedly affected by premature termination codons. We propose that this downstream RNA sequence may interact with ribosomes translating gag to stabilize the RNA.

Asunto(s)

Virus del Sarcoma Aviar/genética , Genes gag , Genes pol , ARN Viral/química , Animales , Secuencia de Bases , Línea Celular , Embrión de Pollo , Regulación Viral de la Expresión Génica , Productos del Gen gag/genética , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Sistemas de Lectura Abierta , Biosíntesis de Proteínas , Proteínas/metabolismo , ARN Mensajero/metabolismo , Ribosomas/metabolismo , Eliminación de Secuencia , Fracciones Subcelulares/microbiología

RESUMEN

The intracellular accumulation of the unspliced RNA of Rous sarcoma virus was decreased when translation was prematurely terminated by the introduction of nonsense codons within its 5' proximal gene, the gag gene. In contrast, the levels of spliced viral RNAs were not affected in our transient expression assays in chicken cells. Experiments using the transcription inhibitor dactinomycin showed that mutant unspliced RNAs were degraded more rapidly than wild-type RNA. Furthermore, mutant RNAs could be partially stabilized by coexpression of wild-type gag proteins in trans; however, intact gag proteins were not required to maintain the stability of RNAs which did not contain premature termination codons. Thus, termination codons seemed to destabilize the RNA not because of their effect on gag protein function but instead because they disrupted the process of translating the gag region of the RNA. Analysis of double-mutant constructs containing both deletions and termination codons within the gag gene also suggested that the stability of the unspliced RNA was affected by a cis-acting interaction between the RNA and ribosomes.

Asunto(s)

Virus del Sarcoma Aviar/genética , Codón/genética , Genes gag , ARN Viral/genética , Animales , Células Cultivadas , Embrión de Pollo , Deleción Cromosómica , Clonación Molecular , Fibroblastos , Mutagénesis Insercional , Plásmidos , Biosíntesis de Proteínas , Empalme del ARN , ARN Viral/metabolismo , Mapeo Restrictivo , Transcripción Genética , Transfección

RESUMEN

Blood pressure and heart rate responses of the spontaneously hypertensive rat (SHR) and the Wistar-Kyoto rat (WKY) to mild restraint and tone-shock pairings were compared during a pre-stress, aversive conditioning and post-stress period, after five previous days of exposure to the paradigm. Although SHR and WKY showed similar responses to the onset of the pre-stress period, SHR showed significantly larger blood pressure responses following the onset of the conditioning than WKY. Furthermore, WKY showed a significant blood pressure and heart rate reduction during the conditioning session which was absent in the SHR. During the post-stress period, the blood pressure of SHR remained significantly elevated compared to their home cage rest values, but the blood pressure of WKY returned to basal levels. It is concluded that while the SHR is more reactive than the WKY to stimulus onset, the major source of between-strain differences after 20 min relates to differences in adaptation to continued environmental stimulation. This can lead to exaggerated estimates of physiological reactivity of the SHR, and is supportive of Folkow's view that SHR are both hyperreactive and show more prolonged defense reactions.

Asunto(s)

Presión Sanguínea , Frecuencia Cardíaca , Estrés Fisiológico/fisiopatología , Animales , Condicionamiento Clásico/fisiología , Electrochoque , Hipertensión/fisiopatología , Masculino , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKY , Sonido , Especificidad de la Especie

RESUMEN

The purpose of this study was to examine the systolic blood pressure and plasma renin activity (PRA) responses to chronic stress in normotensive rats and in rats with one hypertensive parent. Twenty-four male Wistar-Kyoto (WKY) and 24 male F1 offspring of spontaneously hypertensive and WKY rats (BHR) were randomly assigned to 3 groups of 8 each. Experimental (E) animals were subjected to 2 hr daily of shock-shock conflict. Each response produced a 0.2 sec, 0.2-0.4 mA cutaneous electric shock. Failure to respond in 10 sec resulted in a train of 5 shocks (0.2 sec each sec). Yoked animals (Y) received the same shocks as E but had no control over their presentation. Finally, a control group (C) for maturation received no shocks. The E and Y animals were subjected to 14 weeks of conflict and were then monitored an additional 14 weeks in the absence of shock. All animals had their tail cuff blood pressures taken weekly except for 3 times when bloods were obtained for PRA assays. Analysis of blood pressure data revealed that:(1) BHR animals showed more of a blood pressure response to shock than WKY animals; (2) Y animals showed more of a response to conflict than E, especially for the BHR group; and (3) BHR shocked animals remained permanently elevated compared to BHR control animals even in the 14 week post-conflict period during which no shocks were given. Although PRAs for BHR animals were significantly higher than for WKY at the beginning of study, the stress-induced hypertension was associated with either normal or suppressed PRA values, suggesting that the hypertension in these animals is not a high renin hypertension.

Asunto(s)

Presión Sanguínea , Hipertensión/complicaciones , Renina/sangre , Estrés Fisiológico/complicaciones , Animales , Enfermedad Crónica , Hipertensión/fisiopatología , Masculino , Ratas , Ratas Endogámicas , Estrés Fisiológico/fisiopatología

RESUMEN

Repeated attempts to produce hypertension (HT) through psychological stress have failed to elevate blood pressure (BP) to levels seen in chronic, untreated essential HT in humans. In general, these studies have two characteristics in common: they utilize the normotensive animal, with no genetic history of HT, and they involve stressors to which animals readily adapt. The present study utilized offspring with one HT parent. The male F1, offspring of SHR x WKY had borderline HT (-/x +/- SEM = 152.4 +/- 1.34 mm Hg). With a conflict paradigm used as the stressor, experimental animals eventually developed severe HT (188.3 +/- 2.70 mm Hg) compared to two non-stressed control groups (158.4 +/- 2.31 mm Hg and 151.9 +/- 2.25 mm Hg). After 15 weeks of stress for 2 hours daily, termination of conflict for 10 weeks did not reduce the HT in experimental animals. Subsequent analyses revealed that stressed animals, when compared to nonstressed controls, exhibited elevated heart-weight-to-body-weight ratios and significant cardiac pathology in the form of myofibrillar degeneration, accumulation of inflammatory cells, and fibrosis. The implications of using this model for the analysis of cardiovascular concomitants of stress-induced HT are discussed.

Asunto(s)

Presión Sanguínea , Hipertensión/etiología , Miocardio/patología , Estrés Psicológico/complicaciones , Análisis de Varianza , Animales , Reacción de Prevención , Peso Corporal , Femenino , Humanos , Hipertensión/patología , Hipertensión/fisiopatología , Masculino , Ratas

Asunto(s)

Reacción de Prevención/fisiología , Presión Sanguínea , Conflicto Psicológico , Frecuencia Cardíaca , Animales , Peso Corporal , Masculino , Castigo , Ratas , Esquema de Refuerzo

RESUMEN

1. This study sought to develop an animal model which would be prone to stress-induced hypertension without spontaneously developing it. 2. Eighteen male rats, F1 offspring of spontaneously hypertensive x Wistar-Kyoto rats, had tail-cuff systolic blood pressures of 152 mmHg at 12 weeks of age. Animals were randomly assigned to three groups of six each: experimental (subjected to 'conflict' 2 h daily for 12 weeks), restraint control (placed in conditioning cages but not subjected to conflict) and maturation control (neither restrained nor stressed). 3. Systolic blood pressure rose significantly in experimental animals to 186 mmHg. Experimental animals studied for a 10 week follow-up period without conflict maintained the elevated pressure. In addition, these animals showed myofibrillar degeneration and an elevation in heart weight/body weight ratios. Restraint animals showed a modest elevation in pressure during the study, but not during the 10 week follow-up. Maturation animals showed no changes in blood pressure. 4. The development of a model of hypertension combining genetics with psychological stress may serve as a means for determining the factors involved in triggering and sustaining stress-induced hypertension which may prove relevant to essential hypertension in man.

Asunto(s)

Hipertensión/fisiopatología , Estrés Psicológico/fisiopatología , Animales , Presión Sanguínea , Conflicto Psicológico , Modelos Animales de Enfermedad , Humanos , Hipertensión/etiología , Hipertensión/patología , Masculino , Miocardio/patología , Tamaño de los Órganos , Ratas , Estrés Psicológico/complicaciones , Factores de Tiempo

Asunto(s)

Presión Sanguínea , Conflicto Psicológico , Hipertensión/genética , Animales , Femenino , Hipertensión/psicología , Masculino , Ratas

RESUMEN

Three interrelated studies were conducted to examine the locomotor activity of lead-exposed mice. The effects of lead were examined as a function of the dose and duration of exposure. Exposure during the first three weeks occurred via the maternal milk supply. Exposure following weaning was achieved via the water supply. Mice received challenges with various pharmaceutical agents, including d-amphetamine, methylphenidate, apomorphine and phenobarbital. The spontaneous activity prior to injection and the drug-induced activity were monitored. Lead-exposed mice usually displayed spontaneous activity which was indistinguishable from that of the control animals. In only one set of observations did lead exposure result in a modest increase in spontaneous activity. The drug-induced activity varied in a complex manner as a function of the magnitude and duration of the lead exposure. Depressed body weight, which was concurrent with high lead exposure (0.5% Pb(Ac)2) was also a significant parameter affecting both the spontaneous and drug-induced activity.

Asunto(s)

Intoxicación por Plomo/psicología , Actividad Motora/efectos de los fármacos , Factores de Edad , Animales , Apomorfina/farmacología , Peso Corporal/efectos de los fármacos , Química Encefálica/efectos de los fármacos , Dextroanfetamina/farmacología , Conducta de Ingestión de Líquido/efectos de los fármacos , Femenino , Intoxicación por Plomo/metabolismo , Metilfenidato/farmacología , Ratones , Fenobarbital/farmacología , Embarazo