PT  - JOURNAL ARTICLE
AU  - Elizaveta Radion
AU  - Valeriya Morgunova
AU  - Sergei Ryazansky
AU  - Natalia Akulenko
AU  - Sergey Lavrov
AU  - Yuri Abramov
AU  - Pavel A. Komarov
AU  - Sergey I. Glukhov
AU  - Ivan Olovnikov
AU  - Alla Kalmykova
TI  - Key role of piRNAs in telomeric chromatin maintenance and telomere nuclear positioning in <em>Drosophila</em> germline
AID  - 10.1101/163030
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 163030
4099  - http://biorxiv.org/content/early/2018/04/09/163030.short
4100  - http://biorxiv.org/content/early/2018/04/09/163030.full
AB  - Telomeric small RNAs related to PIWI-interacting RNAs (piRNAs) were discovered in different species, however, their role in germline-specific telomere function remains poorly understood. Using a Drosophila model, we show that the piRNA pathway provides a strong germline-specific mechanism of telomere homeostasis. We show that telomeric retrotransposon arrays belong to a unique class of dual-strand piRNA clusters whose transcripts, required for telomere elongation, serve simultaneously as piRNA precursors and their only targets. However, the ability to produce piRNAs and bind Rhino – a germline-specific homolog of heterochromatic protein 1 (HP1) – varies along telomeres. Most likely, this heterogeneity is determined by the peculiarities of telomeric retrotransposons themselves. piRNAs play a pivotal role in the establishment and maintenance of telomeric and subtelomeric chromatin in the germline facilitating loading of HP1 and histone 3 lysine 9 trimethylation mark – highly conservative telomere components – at different telomeric regions. piRNA pathway disruption results in telomere dysfunction characterized by a loss of heterochromatic components and translocation of telomeres from the periphery to the nuclear interior but does not affect the telomere end capping.