RESUMEN
Many diseases with a major public health impact are the result of complex interactions between environmental factors and multiple genes. In the past decade, methods for genome analysis, in particular quantitative trait locus (QTL) analysis in animal models, were developed to identify and localize the genes responsible for multifactorial (polygenic) diseases; QTL analysis is based on experimental crosses between inbred strains with high and low genetic susceptibility. Recently the genes underlying several QTLs could be cloned successfully. Here we describe the impact of these genomic approaches in mice on our understanding of the multifactorial genetics of three gastrointestinal diseases related to metabolism (cholesterol cholelithiasis), development (gastroschisis), and colorectal cancer. The examples demonstrate how mouse models continue to be an invaluable tool in unravelling complex pathomechanisms and unlocking our understanding of human diseases.
Asunto(s)
Modelos Animales de Enfermedad , Enfermedades Gastrointestinales/genética , Predisposición Genética a la Enfermedad , Animales , Colelitiasis/genética , Neoplasias Colorrectales/genética , Gastrosquisis/genética , Humanos , Ratones , Sitios de Carácter CuantitativoRESUMEN
Female hybrid mice (C57BL/6J x HLG) were exposed to 0.5 Gy of cyclotron neutrons (mean energy 5.8 MeV) after mating with HLG males when embryos were at the early zygote stage. Uterine contents were examined on gestation day 19 for prenatal mortality and malformed development. The results were compared to those obtained after irradiation of zygotes with 1.0 and 1.7 Gy X rays. The number of malformed fetuses was greater than for the unirradiated controls. Gastroschisis was the main observation, but exencephaly was also observed. The neutron relative biological effectiveness (RBE) for the induction of lethal events and malformations in the [(C57BL/6J x HLG)F(1)x HLG] mice was estimated. This value is higher than that for the RBE calculated for the HLG strain, which is known to be more sensitive to radiation than the hybrids.
Asunto(s)
Anomalías Congénitas/etiología , Ratones Endogámicos/genética , Neutrones/efectos adversos , Animales , Relación Dosis-Respuesta en la Radiación , Desarrollo Embrionario y Fetal/efectos de la radiación , Femenino , Masculino , Ratones , Rayos XRESUMEN
Gastroschisis (abdominal wall defects) occurs with a high frequency in the mouse inbred strain HLG compared with C57BL/6J mice. The risk of gastroschisis increases significantly after exposure to irradiation with X-rays during preimplantation development and follows a recessive mode of inheritance for the HLG susceptibility alleles. We have used a backcross strategy and genome-wide microsatellite typing to chromosomally map this trait. A suggestive linkage for a locus responsible for radiation-induced gastroschisis (Rigs1) was found in a region of mouse Chromosome 7.
Asunto(s)
Anomalías Inducidas por Radiación/genética , Cromosomas/genética , Gastrosquisis/genética , Músculos Abdominales/anomalías , Músculos Abdominales/embriología , Músculos Abdominales/efectos de la radiación , Animales , Mapeo Cromosómico , Cruzamientos Genéticos , Femenino , Feto/efectos de los fármacos , Feto/metabolismo , Marcadores Genéticos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos , Embarazo , Rayos XRESUMEN
We present changes in the p53 gene in a group of 70 thyroid tumours and 40 blood samples obtained from children from Belarus. Three thyroid tumours show a polymorphism in exon 6 (codon 213) and 5 tumours show a polymorphism in intron 6, 37 bp upstream to the 5'-end of exon 7. Only one patient has a mutation in exon 7 (codon 258) resulting in an amino acid substitution in the protein p53. The distribution of polymorphisms in the 40 blood samples was as follows: three patients had a polymorphism in exon 6 and two persons had a polymorphism in intron 6. One polymorphism in intron 6 was also found in the group of 30 healthy children from Belarus. The fact that the differences in the sequence in p53 found in the tumours was also seen in the blood of these patients demonstrates that they are polymorphisms not induced by radiation exposure. It is difficult to conclude, if the polymorphisms found by us could be associated with the predisposition to radiation-induced cancer.
Asunto(s)
Genes p53 , Neoplasias Inducidas por Radiación/genética , Polimorfismo Genético , Centrales Eléctricas , Liberación de Radiactividad Peligrosa , Neoplasias de la Tiroides/genética , Proteína p53 Supresora de Tumor/sangre , Adolescente , Carcinoma Papilar/sangre , Carcinoma Papilar/epidemiología , Carcinoma Papilar/etiología , Carcinoma Papilar/genética , Niño , Cocarcinogénesis , Análisis Mutacional de ADN , ADN de Neoplasias/genética , Susceptibilidad a Enfermedades , Exones/genética , Femenino , Humanos , Intrones/genética , Masculino , Neoplasias Inducidas por Radiación/sangre , Neoplasias Inducidas por Radiación/epidemiología , Neoplasias Inducidas por Radiación/etiología , República de Belarús/epidemiología , Neoplasias de la Tiroides/sangre , Neoplasias de la Tiroides/epidemiología , Neoplasias de la Tiroides/etiología , UcraniaRESUMEN
An inbred mouse strain HLG shows a high incidence of gastroschisis after X-ray exposure to the zygotes. About 11% of the fetuses display this malformation after irradiation with 1 Gy. The C57BL-strain does not show the increased frequency of gastroschisis after radiation-exposure to the zygotes. The genetic background of this malformation was investigated in a backcross of HLG x C57BL females to HLG males. The pregnant HLG x C57BL females were irradiated in a stage in which the (HLG x C57BL) x HLG [BC1] embryos were in the 1-cell stage. The frequency of gastroschisis in the BC1 generation was compared with a genetic model of a single recessive mutation with 11% penetrance. This frequency does not fit a single-locus inheritance. The number of loci involved was estimated to be about two or three. HLG mouse strain may be a valuable animal model in the study of polygenic traits.
Asunto(s)
Músculos Abdominales/anomalías , Músculos Abdominales/efectos de la radiación , Anomalías Inducidas por Radiación/genética , Feto/efectos de la radiación , Músculos Abdominales/embriología , Anomalías Inducidas por Radiación/mortalidad , Animales , Cruzamientos Genéticos , Femenino , Muerte Fetal/genética , Hernia/embriología , Hernia/genética , Homocigoto , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos , Modelos Genéticos , Mutación , Embarazo , Rayos XRESUMEN
The number of p53 mutations observed in thyroid carcinomas derived from children from areas contaminated by Chernobyl accident is higher compared with studies on patients who had no contact with radioactivity.
Asunto(s)
Carcinoma Papilar/genética , Genes p53/efectos de la radiación , Neoplasias Inducidas por Radiación/genética , Mutación Puntual , Centrales Eléctricas , Liberación de Radiactividad Peligrosa , Neoplasias de la Tiroides/genética , Adolescente , Adulto , Carcinoma Papilar/etiología , Niño , ADN de Neoplasias/genética , ADN de Neoplasias/efectos de la radiación , Electroforesis/métodos , Exones , Femenino , Amplificación de Genes , Humanos , Masculino , Neoplasias Inducidas por Radiación/etiología , Reacción en Cadena de la Polimerasa , Neoplasias de la Tiroides/etiología , UcraniaRESUMEN
Considerable attention has recently been focused on the fact that the tumor suppressor protein p53 is involved in the cellular response to radiation. In its wild-type form the protein appears to control a cell cycle checkpoint, preventing entry into S-phase following DNA damage. A number of authors observed a radiation induced G1-block in cells expressing wild-type p53, but not in p53 mutant cells. We obtained similar results with four human tumour cell lines as well as two strains of human fibroblasts, whose p53 status was ascertained at the protein as well as DNA levels. In addition to cell cycle delays in exponentially growing cell cultures, we have studied the possible role of the p53 in the transition from quiescence to active proliferation. Cells were irradiated after 6 days of serum-starvation and labelled with BrdU at different times after addition of fresh medium. Entry into S-phase was found to be delayed by several hours in the p53 wild-type cells, but no such effect was observed in the p53 mutants. Where a delay occurred, it was roughly proportional to the X-ray dose. Although it remains to be clarified, whether the cells were delayed only in G1 or also in G0, it is interesting to note that entry into S-phase can be delayed by irradiation in a quiescent state immediately before serum-stimulation, provided the cells are wild-type with respect to p53. Certain differences in the cell cycle response of transformed and untransformed cells were noted.
Asunto(s)
Carcinoma de Células Escamosas/radioterapia , Fase G1/efectos de la radiación , Melanoma/radioterapia , Proteína p53 Supresora de Tumor/efectos de la radiación , Antimetabolitos , Bromodesoxiuridina , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patología , Ciclo Celular/efectos de la radiación , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/efectos de la radiación , División Celular/genética , División Celular/efectos de la radiación , Línea Celular Transformada , Medio de Cultivo Libre de Suero , Daño del ADN , ADN de Neoplasias/genética , ADN de Neoplasias/efectos de la radiación , Fibroblastos/metabolismo , Fibroblastos/efectos de la radiación , Humanos , Masculino , Melanoma/genética , Melanoma/patología , Persona de Mediana Edad , Mutación/genética , Dosificación Radioterapéutica , Fase de Descanso del Ciclo Celular/efectos de la radiación , Fase S/efectos de la radiación , Células Tumorales Cultivadas , Proteína p53 Supresora de Tumor/genéticaRESUMEN
We have used two-dimensional gel electrophoresis to analyse proteins in the skin of mouse foetuses with and without gastroschisis after X-irradiation of embryos during the one-cell stage. An increased phosphorylation of two proteins and a shift in one glycoprotein were observed in the skin of irradiated foetuses with gastroschisis compared with the unirradiated normal controls. These protein changes are specifically associated with this malformation. We discuss the results in terms of mutations related to the irradiation of the one-cell embryo.
Asunto(s)
Músculos Abdominales/anomalías , Anomalías Inducidas por Radiación/metabolismo , Glicoproteínas/análisis , Proteínas/metabolismo , Piel/metabolismo , Animales , Femenino , Masculino , Ratones , FosforilaciónRESUMEN
Using the two-dimensional gel electrophoresis and two systems for computer analysis of the resulting maps, we obtained a good quantitative reproducibility of individual spots of silver-stained and Coomassie Blue-stained gels from mouse fetus liver samples. The GelScan-XL system was established for the evaluation of silver-stained gels. The Gel-Image software has shown to be capable of the analysis of Coomassie Blue-stained gels and autoradiographs. For these systems the linear relationship between defined concentrations of protein loaded on the gel and the resulting integrated intensities of spots were examined. The results show that both systems are efficient to detect quantitative changes in protein expression correlated with malformations in mouse fetuses.
Asunto(s)
Electroforesis en Gel Bidimensional/métodos , Hígado/química , Proteínas/análisis , Piel/química , Animales , Computadores , Electroforesis en Gel de Poliacrilamida/métodos , Feto , Indicadores y Reactivos , Ratones , Ratones Endogámicos , Proteínas/aislamiento & purificación , Reproducibilidad de los Resultados , Colorantes de Rosanilina , Plata , Programas Informáticos , Coloración y EtiquetadoRESUMEN
We have used two-dimensional gel electrophoresis coupled with computer-assisted data analysis to monitor protein expression in the liver of mouse fetuses with and without gastroschisis after X-irradiation of embryos during the 1-cell stage. A significantly higher frequency of changes in protein expression was observed in liver from irradiated fetuses with gastroschisis than from irradiated fetuses without gastroschisis. It was found that the frequency of abnormal protein patterns in the malformed fetuses is higher by approximately a factor of 2. Two proteins showed changes simultaneously in liver, kidney and/or skin of one individual fetus. The changes in protein expression probably result from mutations induced by the radiation exposure of the embryos at the 1-cell stage of prenatal development. We discuss these results in terms of increased mutation frequencies in irradiated fetuses with gastroschisis.
Asunto(s)
Abdomen/anomalías , Feto/efectos de los fármacos , Proteínas/metabolismo , Animales , Computadores , Electroforesis en Gel Bidimensional , Riñón/metabolismo , Hígado/embriología , Hígado/metabolismo , Ratones , Ratones Endogámicos , Mutación , Piel/metabolismo , Estadística como AsuntoRESUMEN
Cysts of Naegleria gruberi have a normal UV- and an extremely high X-ray resistance compared to other protozoans. Caffeine and 3-aminobenzamide applied to excysting amoeba after irradiation in the encysted state (UV and X-rays) by feeding with drug-containing bacteria increased lethality, while fractionated irradiation (UV) and liquid-holding (UV and X-rays) increased survival. Illumination with visible light after UV-irradiation restored almost 100% viability. The results are discussed in regard to the activity of repair mechanisms.