Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Cell Sci ; 121(Pt 7): 1014-24, 2008 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-18334554

RESUMO

Spatial organisation of nuclear compartments is an important regulator of chromatin function, yet the molecular principles that maintain nuclear architecture remain ill-defined. We have used RNA interference to deplete key structural nuclear proteins, the nuclear lamins. In HeLa cells, we show that reduced expression of lamin B1, but not lamin A/C, severely inhibits RNA synthesis--first by RNA polymerase II and later by RNA polymerase I. Declining levels of transcription correlate with different morphological changes in major nuclear compartments, nucleoli and nuclear speckles. Ultimately, nuclear changes linked to the loss of synthetic activity result in expansion of the inter-chromatin domain and corresponding changes in the structure and spatial organisation of chromosome territories, which relocate towards the nuclear periphery. These results show that a lamin B1-containing nucleoskeleton is required to maintain RNA synthesis and that ongoing synthesis is a fundamental determinant of global nuclear architecture in mammalian cells.


Assuntos
Núcleo Celular/metabolismo , Lamina Tipo B/metabolismo , Matriz Nuclear/metabolismo , RNA/biossíntese , Apoptose/genética , Apoptose/fisiologia , Western Blotting , Células Cultivadas , Imunofluorescência , Células HeLa , Humanos , Hibridização in Situ Fluorescente , Lamina Tipo A/genética , Lamina Tipo A/metabolismo , Lamina Tipo A/fisiologia , Lamina Tipo B/genética , Lamina Tipo B/fisiologia , Microscopia de Fluorescência , RNA/genética , Interferência de RNA , RNA Polimerase I/metabolismo , RNA Polimerase II/metabolismo
2.
Biophys J ; 93(5): 1778-86, 2007 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-17416613

RESUMO

As exciting light in a scanning confocal microscope encounters a cell and its subcellular components, it is refracted and scattered. A question arises as to what proportion of the exciting light is scattered by subcellular structures and whether cells in the vicinity of the imaged area, i.e., cells that are not directly illuminated by the laser beam, can be affected by either an exposure to scattered light and ensuing phototoxic reactions, or by the products of photoactivated reactions diffusing out of the directly illuminated area. We have designed a technique, which allows us to detect subtle cell photodamage and estimate the extent and range of phototoxic effects inflicted by interaction between scattered exciting light and fluorescent probes in the vicinity of the illuminated area. The technique is based on detecting an increased influx of acridine orange into photodamaged cells, which is manifested by a change of color. We demonstrate that phototoxic effects can be exerted not only on the illuminated cell, but also on fluorescently labeled neighboring cells. The damage inflicted on neighbors is due to exposure to light scattered by the imaged (i.e., directly illuminated) cell, but not phototoxic products diffusing out of the directly illuminated area. When light encounters a cell nucleus, scattering is so intense that photodamage can be inflicted even on fluorescently labeled cells located within a radius of approximately 90 microm, i.e., several cell diameters away. This range of scattering is comparable with that caused by the glass bead resting on a coverslip (up to 120 microm). The intense scattering of exciting light imposes limits on FRAP, FLIP, and other techniques employing high intensity laser beams.


Assuntos
Biofísica/métodos , Microscopia Confocal/métodos , Microscopia de Fluorescência/métodos , Laranja de Acridina/farmacologia , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Recuperação de Fluorescência Após Fotodegradação , Corantes Fluorescentes/farmacologia , Células HeLa , Humanos , Processamento de Imagem Assistida por Computador , Lasers , Luz , Fotoquímica/métodos , Espalhamento de Radiação
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...