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High-throughput Screening for Protein-based Inheritance in S. cerevisiae
Published on: August 8, 2017
The Spi1/PU.1 transcription factor accelerates replication fork progression by increasing PP1 phosphatase in leukemia
Pauline Rimmelé1,2, Michela Esposito3,4, Laure Delestré3,4
1Institut Curie, Paris, France.
Oncotarget
|April 19, 2017
Summary
Oncogenic transcription factor Spi1/PU.1 overexpression causes faster DNA replication by lowering CHK1 phosphorylation via increased PP1α phosphatase activity, impacting cancer progression.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- Oncogenes induce replicative stress, contributing to genetic instability and cancer progression.
- Understanding cellular responses to replicative stress is crucial for identifying cancer treatment targets.
- Constitutive Spi1/PU.1 overexpression leads to pre-leukemic cells with accelerated replication and increased mutability.
Purpose of the Study:
- To investigate the mechanism by which Spi1/PU.1 overexpression affects DNA replication.
- To determine the role of the S phase checkpoint protein CHK1 in Spi1/PU.1-driven replication changes.
- To identify novel pathways linking oncogenes to replication dynamics.
Main Methods:
- Analysis of CHK1 phosphorylation status in Spi1/PU.1-overexpressing cells.
- Investigation of the ATR kinase pathway's involvement.
- Assessment of Protein Phosphatase 1-alpha (PP1α) expression and activity.
- Exogenous modulation of PP1α activity to observe effects on CHK1 phosphorylation and replication fork speed.
Main Results:
- Spi1/PU.1-overexpressing cells exhibit a low phosphorylation state of CHK1, independent of ATR.
- Increased expression of the CHK1 phosphatase PP1α was observed in these cells.
- PP1α activity is essential for maintaining CHK1 dephosphorylation.
- PP1α is responsible for the accelerated replication fork progression in Spi1/PU.1-overexpressing cells.
Conclusions:
- A novel pathway involving PP1α-mediated dephosphorylation of CHK1 contributes to accelerated DNA replication under oncogene expression.
- This mechanism operates independently of DNA damage, highlighting a new facet of oncogene-induced replication stress.
- Targeting this pathway could offer new strategies for antitumor therapies.
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