Related Experiment Video

Updated: Aug 27, 2025

Assessing Cellular Target Engagement by SHP2 PTPN11 Phosphatase Inhibitors
08:45

Assessing Cellular Target Engagement by SHP2 PTPN11 Phosphatase Inhibitors

Published on: July 17, 2020

6.3K

Both phosphorylation and phosphatase activity of PTEN are required to prevent replication fork progression during

Sandip Misra1, Sougata Ghosh Chowdhury2, Ginia Ghosh2

  • 1PG Department of Microbiology, Bidhannagar College, EB-2 Sector-1, Saltlake, Kolkata, India.

Mutation Research
|September 26, 2022
PubMed

Insights

Phosphatase and tensin homolog (PTEN) acts as a crucial stress sensor during DNA replication. Its C-terminal phosphorylation enables chromatin binding, promoting cell cycle arrest and maintaining genomic stability in cancer cells.

Area of Science:

  • Cancer Biology
  • Molecular Oncology
  • Genomic Stability

Background:

  • PTEN is a tumor suppressor protein often altered in cancers, and PTEN-null cells exhibit rapid proliferation and genomic instability.
  • Replication stress can lead to genomic instability if not properly sensed by cellular signaling pathways.
  • The role of PTEN's catalytic function, modulated by posttranslational modifications, in responding to replication stress is not fully understood.

Purpose of the Study:

  • To investigate the molecular mechanisms by which PTEN responds to replication stress.
  • To elucidate the role of PTEN's posttranslational modifications, specifically C-terminal phosphorylation, in its function during replication stress.
  • To understand how PTEN regulates cell cycle progression and genomic stability under replication stress conditions.

Main Methods:

  • DNA fiber assays to assess replication fork progression.
  • Ectopic expression of full-length and mutant PTEN.
  • Analysis of PTEN's chromatin association and its effect on heterochromatin formation (H3K9me3 foci).
  • Assessment of cell cycle arrest and CHK1 activation.

Main Results:

  • PTEN-null cells show unrestrained replication fork progression and DNA damage accumulation upon aphidicolin treatment, which is rescued by PTEN re-expression.
  • C-terminal phosphorylation of PTEN (Ser 380, Thr 382/383) is critical for its chromatin association and sensing of replication stress, leading to cell cycle arrest.
  • Phosphatase-dead PTEN associates with chromatin but cannot sense replication stress.
  • PTEN induces HP1α expression and H3K9me3 foci formation in a C-terminal phosphorylation-dependent manner, augmenting CHK1 activation.

Conclusions:

  • PTEN acts as a stress-sensing protein during replication arrest, with its C-terminal phosphorylation mediating chromatin association and heterochromatin formation.
  • PTEN prevents excessive DNA replication fork elongation and induces G1-S phase cell cycle arrest to maintain genomic stability.
  • These findings highlight PTEN's critical role in preventing uncontrolled proliferation and maintaining genome integrity in cancer cells under stress.
Keywords:
HeterochromatinPTENPhosphatase activityPhosphorylationReplication

More Related Videos

Examination of Proteins Bound to Nascent DNA in Mammalian Cells Using BrdU-ChIP-Slot-Western Technique09:14

Examination of Proteins Bound to Nascent DNA in Mammalian Cells Using BrdU-ChIP-Slot-Western Technique

Published on: January 14, 2016

9.3K
Author Spotlight: Quantitative Detection of DNA Protein Crosslinks and Their Post-Translational Modifications10:12

Author Spotlight: Quantitative Detection of DNA Protein Crosslinks and Their Post-Translational Modifications

Published on: April 21, 2023

2.9K

Related Concept Videos

Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart,...
5.9K
DNA Damage can Stall the Cell Cycle02:37

DNA Damage can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
9.3K
PI3K/mTOR/AKT Signaling Pathway01:22

PI3K/mTOR/AKT Signaling Pathway

The mammalian target of rapamycin  (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1  (mTORC1) and mTOR complex 2  (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast,  mTORC2 consists of a...
3.8K
Negative Regulator Molecules01:23

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
35.7K
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the...
4.6K
The DNA Replication Fork01:02

The DNA Replication Fork

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication...
36.5K