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Characterization of chromatin mobility upon DNA damage in Arabidopsis thaliana

Meschichi, Anis (2022). Characterization of chromatin mobility upon DNA damage in Arabidopsis thaliana. Diss. (sammanfattning/summary) Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880
ISBN 978-91-7760-975-9
eISBN 978-91-7760-976-6
[Doctoral thesis]

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Abstract

Plant cells are subject to high levels of DNA damage from dependence on sunlight for energy and the associated exposure to biotic and abiotic stresses. Double-strand breaks (DSBs) are a particularly deleterious type of DNA damage, potentially leading to chromosome rearrangements or loss of entire chromosome arms. The presence of efficient and accurate repair mechanisms may be particularly important for sedentary organisms with late separation of the germline, such as plants. DSB repair is accomplished by two main pathways: nonhomologous end joining (NHEJ) and homologous recombination (HR). NHEJ is achieved by stabilization and re-ligation of broken DNA ends, often with a loss or mutation of bases. HR is a more complex and conservative mechanism in which intact homologous regions are used as a template for repair. The molecular mechanisms that control DSB signaling and repair have been characterized extensively. Nonetheless, little is known about how the homology search happens in the crowded space of the cell nucleus. This thesis reveals the methodology to capture chromatin motion to investigate nuclear dynamics in different developmental and cellular contexts. Using live imaging approaches, we measured chromosome mobility by tracking the motion of specific loci using the lacO/LacI and ParB/parS tagging systems in Arabidopsis thaliana.Our results have shown that chromatin mobility is affected by cell differentiation level, cell cycle phase, or genomic position, and that chromatin mobility increases when DNA damage is induced. Moreover, we observed an increase in chromatin mobility upon the induction of DNA damage, specifically at the S/G2 phases of the cell cycle. Importantly, this increase in mobility in S/G2 was lost on sog1-1 mutant, a central transcription factor of the DNA damage response (DDR), indicating that repair mechanisms actively regulate chromatin mobility upon DNA damage. Studies have shown that HR is the predominant DSB repair pathway occurring during S/G2 phase. Therefore, we investigated the mobility of two GFP-tagged HR regulators, RAD51 and RAD54, corresponding to early and late HR. DSB sites show remarkably high mobility levels at the early HR stage. Subsequently, a drastic decrease in DSB mobility is observed, which seems to be associated with the relocation of DSBs to the nucleus periphery.Altogether, our study suggests chromatin mobility as a non-negligible factor for DNA repair in plants, which may facilitate physical searching in the nuclear space thereby helping to locate a homologous template during homology-directed DNA repair.

Authors/Creators:Meschichi, Anis
Title:Characterization of chromatin mobility upon DNA damage in Arabidopsis thaliana
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2022
Number:2022:50
Number of Pages:80
Publisher:Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-975-9
ISBN for electronic version:978-91-7760-976-6
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution-Noncommercial-No Derivative Works 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Agricultural Science
Keywords:Arabidopsis, chromatin mobility, DNA damage, SOG1, RAD51, homologous recombination, cell cycle, chromatin dynamic, mean square displacement, DNA damage response
URN:NBN:urn:nbn:se:slu:epsilon-p-118378
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-118378
ID Code:28512
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Deposited By: SLUpub Connector
Deposited On:22 Aug 2022 12:30
Metadata Last Modified:12 Sep 2022 11:32

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