View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by RERO DOC Digital Library CMLS, Cell. Mol. Life Sci. 60 (2003) 2303–2318 1420-682X/03/112303-16 DOI 10.1007/s00018-003-3246-x CMLS Cellular and Molecular Life Sciences © Birkhäuser Verlag, Basel, 2003 Long-range silencing and position effects at telomeres and centromeres: parallels and differences S. Perrod and S. M. Gasser* University of Geneva, Department of Molecular Biology, Quai Ernest-Ansermet 30, 1211 Geneva 4 (Switzerland), Fax: +41 22 379 6868, e-mail
[email protected] Abstract. Most of the human genome is compacted into dress the mechanisms of centromeric, telomeric and lo- heterochromatin, a form that encompasses multiple cus-specific gene silencing, comparing simple and com- forms of inactive chromatin structure. Transcriptional si- plex animals with yeast. Some aspects are universally lencing mechanisms in budding and fission yeasts have shared, such as histone-tail modifications, while others provided genetically tractable models for understanding are unique to either centromeres or telomeres. These may heritably repressed chromatin. These silent domains are reflect roles for heterochromatin in other chromosomal typically found in regions of repetitive DNA, that is, ei- functions, like kinetochore attachment and DNA ends ther adjacent to centromeres or telomeres or within the protection. tandemly repeated ribosomal DNA array. Here we ad- Key words. Silencing; PEV; yeast; SIR protein; epigenetics; Drosophila; telomeres; rDNA. Comparison of long-range silencing with generally refers to noncoding satellite repeats. Faculta- heterochromatin tive heterochromatin can be specific to one of two ho- mologous chromosomes, or to a certain cell type or de- Long-range silencing generates a heritable, transcription- velopmental stage, and leads to the repression of unique ally inactive chromatin structure that is associated with sequences rich in genes.