BFTERRA · Biogenesis and Functions of Telomeric Repeat-containing RNA

Telomeres are heterochromatic nucleoprotein complexes located at the end of linear eukaryotic chromosomes. Contrarily to a longstanding dogma, we have recently demonstrated that mammalian telomeres are transcribed into TElomeric Repeat containing RNA (TERRA) molecules. TERRA transcripts contain telomeric RNA repeats and are produced at least in part by DNA-dependent RNA polymerase II-mediated transcription of telomeric DNA. TERRA molecules form discrete nuclear foci that co-localize with telomeric heterochromatin in both interphase and transcriptionally inactive metaphase cells. This indicates that TERRA is an integral component of telomeres and suggests that TERRA might participate in maintaining proper telomere heterochromatin. We will use a variety of biochemistry, cell biology, molecular biology and microscopy based approaches applied to cultured mammalian cells and to the yeast Schizosaccharomyces pombe, to achieve four distinct major goals: i) We will over-express or deplete TERRA in mammalian cells in order to characterize the molecular details of putative TERRA-associated functions in maintaining normal telomere structure and function; ii) We will locate TERRA promoter regions on different human chromosome ends; iii) We will generate mammalian cellular systems in which to study artificially seeded telomeres that can be transcribed in an inducible fashion; iv) We will identify physiological regulators of TERRA by analyzing it in mammalian cultured cells where the functions of candidate factors are compromised. In parallel, taking advantage of the recent discovery of TERRA also in fission yeast, we will systematically analyze TERRA levels in fission yeast mutants derived from a complete gene knockout collection. The study of TERRA regulation and function at chromosome ends will strongly contribute to our understanding of how telomeres are maintained and will help to clarify the general functions of mammalian non-coding RNAs.