Related Experiment Video
Updated: Jun 21, 2025
Quantification of γH2AX Foci in Response to Ionising Radiation
Published on: April 6, 2010
TORC2 is required for the accumulation of γH2A in response to DNA damage
Adiel Cohen1, Lea Lubenski2, Ava Mouzon2
1Department of Natural Sciences, The Open University of Israel, Ranana, Israel.
Abstract:
TOR protein kinases serve as the catalytic subunit of the TORC1 and TORC2 complexes, which regulate cellular growth, proliferation, and survival. In the fission yeast, Schizosaccharomyces pombe, cells lacking TORC2 or its downstream kinase Gad8 (AKT or SGK1 in human cells) exhibit sensitivity to a wide range of stress conditions, including DNA damage stress. One of the first responses to DNA damage is the phosphorylation of C-terminal serine residues within histone H2AX in human cells (γH2AX), or histone H2A in yeast cells (γH2A). The kinases responsible for γH2A in S. pombe are the two DNA damage checkpoint kinases Rad3 and Tel1 (ATR and ATM, respectively, in human cells). Here we report that TORC2-Gad8 signaling is required for accumulation of γH2A in response to DNA damage and during quiescence. Using the TOR-specific inhibitor, Torin1, we demonstrate that the effect of TORC2 on γH2A in response to DNA damage is immediate, rather than adaptive. The lack of γH2A is restored by deletion mutations of transcription and chromatin modification factors, including loss of components of Paf1C, SAGA, Mediator, and the bromo-domain proteins Bdf1/Bdf2. Thus, we suggest that TORC2-Gad8 may affect the accumulation of γH2A by regulating chromatin structure and function.
Insights
TORC2-Gad8 signaling is essential for DNA damage response in yeast. This pathway regulates histone H2A phosphorylation, crucial for DNA repair, and involves chromatin modification factors.
Area of Science:
- Cellular Biology
- Molecular Biology
- Genetics
Background:
- TOR protein kinases are central regulators of cell growth, proliferation, and survival.
- TORC2 complex and its downstream kinase Gad8 are critical for stress response in fission yeast.
- Histone H2A phosphorylation (γH2A) is an early marker of DNA damage.
Purpose of the Study:
- To investigate the role of TORC2-Gad8 signaling in the accumulation of γH2A in response to DNA damage and quiescence.
- To determine if TORC2's effect on γH2A is immediate or adaptive.
Main Methods:
- Utilized the TOR-specific inhibitor Torin1 in Schizosaccharomyces pombe.
- Assessed γH2A accumulation under DNA damage and quiescence.
- Investigated the impact of deleting transcription and chromatin modification factors.
Main Results:
- TORC2-Gad8 signaling is required for γH2A accumulation in response to DNA damage and quiescence.
- The effect of TORC2 on γH2A is immediate upon DNA damage.
- Absence of γH2A can be rescued by mutations in transcription and chromatin modification factors, including Paf1C, SAGA, Mediator, and bromo-domain proteins.
Conclusions:
- TORC2-Gad8 signaling plays a crucial role in the DNA damage response pathway by regulating γH2A.
- TORC2-Gad8 signaling likely influences γH2A accumulation through modulation of chromatin structure and function.
- This suggests a novel link between nutrient sensing pathways and DNA repair mechanisms.
Related Concept Videos
02:37DNA Damage can Stall the Cell Cycle
02:37DNA Damage Can Stall the Cell Cycle
02:25Overview of DNA Repair
02:37Restarting Stalled Replication Forks
00:55DNA Helicases
02:31Homologous Recombination