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Mammalian RNase H1 directs RNA primer formation for mtDNA replication initiation and is also necessary for mtDNA replication completion

Lookup NU author(s): Dr Thomas NichollsORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

The in vivo role for RNase H1 in mammalian mitochondria has been much debated. Loss of RNase H1 is embryonic lethal and to further study its role in mtDNA expression we characterized a conditional knockout of Rnaseh1 in mouse heart. We report that RNase H1 is essential for processing of RNA primers to allow site-specific initiation of mtDNA replication. Without RNase H1, the RNA:DNA hybrids at the replication origins are not processed and mtDNA replication is initiated at non-canonical sites and becomes impaired. Importantly, RNase H1 is also needed for replication completion and in its absence linear deleted mtDNA molecules extending between the two origins of mtDNA replication are formed accompanied by mtDNA depletion. The steady-state levels of mitochondrial transcripts follow the levels of mtDNA, and RNA processing is not altered in the absence of RNase H1. Finally, we report the first patient with a homozygous pathogenic mutation in the hybrid-binding domain of RNase H1 causing impaired mtDNA replication. In contrast to catalytically inactive variants of RNase H1, this mutant version has enhanced enzyme activity but shows impaired primer formation. This finding shows that the RNase H1 activity must be strictly controlled to allow proper regulation of mtDNA replication.


Publication metadata

Author(s): Misic J, Milenkovic D, Al-Behadili A, Xie X, Jiang M, Jiang S, Filograna R, Koolmeister C, Siira SJ, Jenninger L, Filipovska A, Clausen AR, Caporali L, Valentino ML, La Morgia C, Carelli V, Nicholls TJ, Wredenberg A, Falkenberg M, Larsson NG

Publication type: Article

Publication status: Published

Journal: Nucleic Acids Research

Year: 2022

Volume: 50

Issue: 15

Pages: 8749–8766

Print publication date: 26/08/2022

Online publication date: 10/08/2022

Acceptance date: 04/08/2022

Date deposited: 30/08/2022

ISSN (print): 0305-1048

ISSN (electronic): 1362-4962

Publisher: Oxford University Press

URL: https://doi.org/10.1093/nar/gkac661

DOI: 10.1093/nar/gkac661

PubMed id: 35947649


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Funding

Funder referenceFunder name
019.0109
2016.0050
2016-741366
2018-02439
2018-05121
2019-816
2015-00418
2017.008
2021-1409
ALFGBG-72749
213464/Z/18/ZWellcome Trust
ARC
CCWA
Knut and Alice Wallen-bergs Foundation
M811Rosetrees Trust
NHMRC
SLL2018.0471
PRUa1RI- 2012-008

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