RESUMEN
Lamina-associated polypeptide (LAP) 2alpha is a LEM (lamina-associated polypeptide emerin MAN1) family protein associated with nucleoplasmic A-type lamins and chromatin. Using live cell imaging and fluorescence microscopy we demonstrate that LAP2alpha was mostly cytoplasmic in metaphase and associated with telomeres in anaphase. Telomeric LAP2alpha clusters grew in size, formed 'core' structures on chromatin adjacent to the spindle in telophase, and translocated to the nucleoplasm in G1 phase. A subfraction of lamin C and emerin followed LAP2alpha to the core region early on, whereas LAP2beta, lamin B receptor and lamin B initially bound to more peripheral regions of chromatin, before they spread to core structures with different kinetics. Furthermore, the DNA-crosslinking protein barrier-to-autointegration factor (BAF) bound to LAP2alpha in vitro and in mitotic extracts, and subfractions of BAF relocalized to core structures with LAP2alpha. We propose that LAP2alpha and a subfraction of BAF form defined complexes in chromatin core regions and may be involved in chromatin reorganization during early stages of nuclear assembly.
Asunto(s)
Núcleo Celular/metabolismo , Proteínas de Unión al ADN/biosíntesis , Proteínas de la Membrana/biosíntesis , Proteínas Nucleares/biosíntesis , Telómero/ultraestructura , Animales , Proteínas Bacterianas/metabolismo , Línea Celular , Cromatina/metabolismo , Cromosomas/diagnóstico por imagen , Cromosomas/metabolismo , ADN/metabolismo , Proteínas de Unión al ADN/metabolismo , Electroforesis en Gel de Poliacrilamida , Células HeLa , Histonas/metabolismo , Humanos , Procesamiento de Imagen Asistido por Computador , Immunoblotting , Inmunoprecipitación , Riñón/citología , Laminas/metabolismo , Proteínas Luminiscentes/metabolismo , Proteínas de la Membrana/metabolismo , Microscopía Fluorescente , Microtúbulos/ultraestructura , Mitosis , Modelos Biológicos , Proteínas Nucleares/metabolismo , Unión Proteica , Ratas , Telómero/metabolismo , UltrasonografíaRESUMEN
The paper analyzes the significance of new data obtained in the study of mechanism of formation of radiation-induced chromosome aberrations and in the investigation of chromatin diminution for understanding of the principles of the molecular genetical organization of eucaryotic chromosome. It is concluded that the structure of eucaryotic chromosome follows a certain plan. For its formation, a large number of various innovations were necessary, which could not been prepared simultaneously under the directed action of natural selection based upon the stochastic mutation process.
Asunto(s)
Cromatina/genética , Aberraciones Cromosómicas/genética , Cromosomas/genética , Células Eucariotas/ultraestructura , Animales , Cromatina/diagnóstico por imagen , Cromosomas/diagnóstico por imagen , ADN/genética , ADN/efectos de la radiación , Células Eucariotas/diagnóstico por imagen , Humanos , Radiografía , Selección GenéticaRESUMEN
Chromosome analysis was performed on five persons before and after urographic examination. Despite a small increase in chromosome aberration frequency after the examination, no statistically significant increase was demonstrated. Whole body lymphocytes were analyzed for chromosome aberrations after exposure to low dose radiation, contrast agents and radiation together with a contrast medium. A significant increase in aberration frequencies at the 2.5% level was observed in irradiated blood samples containing the iodized contrast agent metrizoate.