Resolution of ultrafine anaphase bridges (UFBs) must be completed before cytokinesis to ensure sister-chromatid disjunction. RIF1 is involved in UFB resolution by a mechanism that is not yet clear. Here, we show that RIF1 functions in mitosis to inhibit the formation of 53BP1 nuclear bodies and micronuclei. Meanwhile, RIF1 localizes on PICH-coated double-stranded UFBs but not on RPA-coated single-stranded UFBs. Depletion of RIF1 leads to an elevated level of RPA-coated UFBs, in a BLM-dependent manner. RIF1 interacts with all three isoforms of protein phosphatase 1 (PP1) at its CI domain in anaphase when CDK1 activity declines. CDK1 negatively regulates RIF1-PP1 interaction via the CIII domain of RIF1. Importantly, depletion of PP1 phenocopies RIF1 depletion, and phosphorylation-resistant mutant of PICH shows reduced interaction with the BTR complex and bypasses the need of RIF1 in preventing the formation of single-stranded UFBs. Overall, our data show that PP1 is the effector of RIF1 in UFB resolution.
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http://dx.doi.org/10.1016/j.celrep.2023.112032 | DOI Listing |
Nat Commun
January 2025
IBENS, Département de biologie, École normale supérieure, Université PSL, CNRS, INSERM, 75005, Paris, France.
Current temporal studies of DNA replication are either low-resolution or require complex cell synchronisation and/or sorting procedures. Here we introduce Nanotiming, a single-molecule, nanopore sequencing-based method producing high-resolution, telomere-to-telomere replication timing (RT) profiles of eukaryotic genomes by interrogating changes in intracellular dTTP concentration during S phase through competition with its analogue bromodeoxyuridine triphosphate (BrdUTP) for incorporation into replicating DNA. This solely demands the labelling of asynchronously growing cells with an innocuous dose of BrdU during one doubling time followed by BrdU quantification along nanopore reads.
View Article and Find Full Text PDFNoncoding RNA
November 2024
Department of Functional Genomics, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan.
Our recently created RNA-sequence-based microRNA (miRNA) expression signature in breast cancer clinical specimens revealed that some family members were significantly downregulated in cancer tissues. Based on TCGA database analyses, we observed that among the family members, (the passenger strand derived from pre-) was significantly downregulated in breast cancer (BC) clinical specimens, and its low expression predicted worse prognoses. Ectopic expression assays showed that transfected cancer cells (MDA-MB-157 and MDA-MB-231) had their aggressive phenotypes significantly suppressed, e.
View Article and Find Full Text PDFNucleic Acids Res
December 2024
School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
Incomplete sister centromere decatenation results in centromeric ultrafine anaphase bridges (UFBs). PICH (PLK1-interacting checkpoint helicase), a DNA translocase, plays a crucial role in UFB resolution by recruiting UFB-binding proteins and stimulating topoisomerase IIα. However, the involvement of distinct PICH functions in UFB resolution remains ambiguous.
View Article and Find Full Text PDFHua Xi Kou Qiang Yi Xue Za Zhi
December 2024
Stomatological Hospital of Kunming Medical University, Kunming 650000, China.
bioRxiv
November 2024
Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, 1111 Highland Ave, Madison, WI 53705, USA.
RIF1 (RAP1 interacting factor) fulfills diverse roles in DNA double-strand break repair, DNA replication, and nuclear organization. RIF1 is expressed as two splice variants, RIF1-Long (RIF1-L) and RIF1-Short (RIF1-S), from the alternative splicing (AS) of Exon 32 (Ex32) which encodes a 26 aa Ser/Lys-rich cassette peptide in the RIF1 C-terminal domain (CTD). Here we demonstrate that Ex32 inclusion was repressed by DNA damage and oncogenesis but peaked at G/M phase of the cell cycle.
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