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Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Modulated contact frequencies at gene-rich loci support a statistical helix model for mammalian chromatin organization. | Court et al. Genome Biology 2011 12 R42 http genomebiology.eom 2011 12 5 R42 Genome Biology RESEARCH Open Access Modulated contact frequencies at gene-rieh loei support a statistical helix model for mammalian chromatin organization 12 1 1 11 Franck Court Julie Miro Caroline Braem Marie-Noelle Lelay-Taha Audrey Brisebarre Florian Atger Thierry Gostan 1 Michael Weber1 Guy Cathala1 and Thierry Forné1 Abstract Background Despite its critical role for mammalian gene regulation the basic structural landscape of chromatin in living cells remains largely unknown within chromosomal territories below the megabase scale. Results Here using the 3C-qPCR method we investigate contact frequencies at high resolution within interphase chromatin at several mouse loci. We find that at several gene-rich loci contact frequencies undergo a periodical modulation every 90 to 100 kb that affects chromatin dynamics over large genomic distances a few hundred kilobases . Interestingly this modulation appears to be conserved in human cells and bioinformatic analyses of locus-specific long-range cis-interactions suggest that it may underlie the dynamics of a significant number of gene-rich domains in mammals thus contributing to genome evolution. Finally using an original model derived from polymer physics we show that this modulation can be understood as a fundamental helix shape that chromatin tends to adopt in gene-rich domains when no significant locus-specific interaction takes place. Conclusions Altogether our work unveils a fundamental aspect of chromatin dynamics in mammals and contributes to a better understanding of genome organization within chromosomal territories. Background Within the interphasic cell nucleus the mammalian genome packed into the chromatin is spatially restrained into specific chromosomal territories 1 2 and is distributed in at least two spatial compartments one enriched in active genes and open chromatin 3-7 and the other containing inactive and closed chromatin
