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Antagonistic roles of canonical and alternative-RPA in disease-associated tandem CAG repeat instability

ABSTRACT: Ongoing CAG expansions in Spinocerebellar ataxia type 1 (SCA1) and Huntington disease (HD) brains exacerbate disease. Expansions involve aberrant repair of mutagenic slipped-DNAs, formed from single-stranded DNAs. Whether singlestranded DNA-binding proteins prevent or facilitate expansions is unknown. We assessed canonical RPA (RPA1-RPA2-RPA3) and Alternative-RPA (RPA1-RPA4- RPA3), containing primate-specific RPA4. RPA is essential for all DNA metabolism. Alt-RPA has undefined functions. Alt-RPA is upregulated 10-fold in HD and SCA1 patient brains. RPA enhances, while Alt-RPA blocks, correct repair of slipped-CAGs. RPA, but not Alt-RPA, efficiently binds and melts slipped-DNAs. RPA enhances, while Alt-RPA blocks, removal of excess slipped-DNAs by FAN1 nuclease. Protein-protein interactomes reveal unique and shared partners of RPA and Alt-RPA, including expansion-driving proteins. RPA-overexpression in SCA1 mice inhibits CAG expansions in brains, rescuing neuron morphology and motor phenotypes. Modulating repeat mutations is one example involving antagonistic Alt-RPA↔RPA interactions, illuminating questions as to which RPA-mediated processes are also modulated by AltRPA.

INSTRUMENT(S): autoflex

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Early Embryonic Cell

SUBMITTER: Jennifer Raisch

LAB HEAD: Francois-Michel Boisvert

PROVIDER: PXD044158 | Pride | 2023-10-13

REPOSITORIES: Pride

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RBMX preferentially associates with repetitive DNAs along with RPA

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2019-07-27 | GSE134980 | GEO

RBMX preferentially associates with repetitive DNAs along with RPA

Project description:RBMX preferentially associates with repetitive DNAs along with RPA

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2013-01-02 | E-GEOD-42451 | biostudies-arrayexpress

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Signalling Inhibition by Ponatinib Disrupts Productive Alternative Lengthening of Telomeres (ALT)

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2023-02-20 | PXD037501 | Pride

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2019-09-16 | E-MTAB-8248 | biostudies-arrayexpress

Rtt105 promotes DNA replication by functioning as an RPA chaperone

Project description:Single-stranded DNA (ssDNA) binding protein Replication Protein A (RPA) is essential for protecting ssDNA at replication forks. However, how RPA is loaded to replication forks remains unexplored. Here, we show that Regulator of Ty1 transposition protein 105 (Rtt105) binds RPA and is required for the association of RPA with replication forks. Cells lacking Rtt105 exhibit dramatic genome instability and severe defects in DNA replication. Intriguingly, both the RPA nuclear import and its ability to bind DNA replication forks were greatly compromised in rtt105 mutant cells, however, targeting RPA to the nucleus cannot rescue the defect of RPA binding to replication forks. Importantly, Rtt105 promotes the binding of RPA to ssDNA but does not associate with the final RPA-ssDNA complex in vitro. Moreover, single-molecule studies revealed that Rtt105 affects the binding mode of RPA to ssDNA. These results support a model in which Rtt105 functions as an RPA chaperone that escorts RPA to nucleus and assemble RPA onto ssDNA at replication forks.

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Regulator of Ty1 transposition protein 105 (Rtt105) is an RPA chaperone and is required for genome stability maintenance

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2018-07-27 | GSE87356 | GEO

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