共查询到20条相似文献,搜索用时 46 毫秒
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Successful heterochromatin formation is critical for genome stability in eukaryotes, both to maintain structures needed for mitosis and meiosis and to silence potentially harmful transposable elements. Conversely, inappropriate heterochromatin assembly can lead to inappropriate silencing and other deleterious effects. Hence targeting heterochromatin assembly to appropriate regions of the genome is of utmost importance. Here we focus on heterochromatin assembly in Drosophila melanogaster, the model organism in which variegation, or cell-to-cell variable gene expression resulting from heterochromatin formation, was first described. In particular, we review the potential role of transposable elements as genetic determinants of the chromatin state and examine how small RNA pathways may participate in the process of targeted heterochromatin formation. 相似文献
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Rebuzzini P Pignalosa D Mazzini G Di Liberto R Coppola A Terranova N Magni P Redi CA Zuccotti M Garagna S 《Journal of cellular physiology》2012,227(3):1242-1249
This study aimed to investigate the cell cycle, apoptosis, cytogenetics and differentiation capacity of mouse embryonic stem cells (mESCs) that survived a single dose of 2 or 5 Gy γ-rays during a period of up to 96 h of culture. After 2 Gy irradiation and 24 h culture, compared to control, a significant majority of cells was blocked at the G2/M phase and a massive apoptosis was recorded. Between 48 and 72 h post-irradiation, the parameters used to describe the cell cycle and apoptosis returned similar to those of control samples. When mESCs were irradiated with 5 Gy, a small fraction of cells, even after 96 h of culture, still presented clear evidences of a G2/M block and apoptosis. The cytogenetic analysis performed at 96 h showed that the structural stability of the aberrations did not change significantly when comparing control and 2 or 5 Gy-treated populations. However, the chromosomal damage observed in the progeny of the survived cells after 5 Gy exposure is significantly higher than that observed in control samples, although it is mostly of the stable and transmissible type. Ninety-six hours after irradiation, the survived mESCs maintained their undifferentiated status and capability to differentiate into the three germ layers. Overall, these results indicate a commitment of mESCs to maintain pluripotency and genome stability. 相似文献
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Corella S. Casas-Delucchi Annette Becker Janine J. Bolius M. Cristina Cardoso 《Nucleic acids research》2012,40(22):e176
Heterochromatic regions represent a significant portion of the mammalian genome and have been implied in several important cellular processes, including cell division and genomic stability. However, its composition and dynamics remain largely unknown. To better understand how heterochromatin functions and how it is organized within the context of the cell nucleus, we have developed molecular tools allowing the targeting of virtually any nuclear factor specifically to heterochromatic regions and, thereby, the manipulation, also in a temporally controlled manner, of its composition. To validate our approach, we have ectopically targeted MeCP2 chromatin binding deficient Rett mutants to constitutive heterochromatic regions and analyze its functional consequences. We could show that, once bound to their endogenous target regions, their ability to re-organize higher order chromatin structure is restored. Furthermore, a temporally controlled targeting strategy allowed us to monitor MeCP2-mediated chromatin rearrangements in vivo and to visualize large-scale chromatin movements over several micrometers, as well as heterochromatic foci fusion events. This novel strategy enables specific tethering of any protein to heterochromatin and lays the ground for controlled manipulation of its composition and organization. 相似文献
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