Please use this identifier to cite or link to this item: http://doi.org/10.25358/openscience-3578
Authors: Perez Martinez, Lara
Title: Npl3 stabilizes R-loops at telomeres to regulate replicative senescence
Online publication date: 11-Dec-2019
Language: english
Abstract: Telomeres are the end structures of eukaryotic chromosomes, which are subject to the end-replication problem and undergo progressive shortening unless elongated by the reverse-transcriptase telomerase. In the absence of telomerase, short telomeres can stop cell cycle progression in a process called replicative senescence. Telomeres are transcribed into the long non-coding RNA TERRA which is able to hybridize with the telomere, forming a homologous recombination-prone structure called an R-loop. In yeast, telomeric R-loop levels increase during senescence and delay senescence rate, supporting a role of TERRA R-loops in replicative senescence. In this study, we performed quantitative interactomics to identify proteins binding to telomeres in S. cerevisiae. Using a DNA pull-down strategy and protein extracts from telomerase positive and telomerase negative cells, we identified proteins that associate to telomeres. We identified a set of telomere associated proteins that showed enrichment in RNA regulatory functions and helicase functions. This suggests that RNA binding proteins and helicases may be important for telomere integrity and the regulation of senescence in yeast. Among our candidates, we identified the yeast hnRNP-like protein Npl3 and further characterize its function at short telomeres. We first validated its in vivo binding to telomeres and showed that Npl3 displays a strong association to short telomeres. Importantly, deletion of NPL3 has been reported to cause a fast senescence phenotype. We show that TERRA mediates the Npl3 recruitment to telomeres, as changes in TERRA and TERRA R-loop levels modulate the binding of Npl3 to telomeres. This suggests that the accumulation of TERRA and R-loops at short telomeres may recruit Npl3. Using a combination of genetic and biochemical approaches we also show that NPL3 can stabilize R-loops when overexpressed, suggesting that local accumulation of Npl3 can stabilize pre-formed R-loops. Further, we demonstrate that Npl3 stabilizes R-loops at telomeres. Altogether, our data supports a model in which TERRA recruits Npl3 to short telomere to stabilize telomeric R-loops and prevent premature senescence in yeast.
DDC: 570 Biowissenschaften
570 Life sciences
Institution: Johannes Gutenberg-Universität Mainz
Department: Externe Einrichtungen
Place: Mainz
DOI: http://doi.org/10.25358/openscience-3578
Version: Original work
Publication type: Dissertation
License: in Copyright
Information on rights of use: https://rightsstatements.org/vocab/InC/1.0/
Extent: vi, 116 Seiten
Appears in collections:JGU-Publikationen

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