Related Experiment Videos
c-Abl tyrosine kinase regulates the human Rad9 checkpoint protein in response to DNA damage
Kiyotsugu Yoshida1, Kiyoshi Komatsu, Hong-Gang Wang
1Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
Abstract:
The ubiquitously expressed c-Abl tyrosine kinase is activated in the apoptotic response of cells to DNA damage. The mechanisms by which c-Abl signals the induction of apoptosis are not understood. Here we show that c-Abl binds constitutively to the mammalian homolog of the Schizosaccharomyces pombe Rad9 cell cycle checkpoint protein. The SH3 domain of c-Abl interacts directly with the C-terminal region of Rad9. c-Abl phosphorylates the Rad9 Bcl-2 homology 3 domain (Tyr-28) in vitro and in cells exposed to DNA-damaging agents. The results also demonstrate that c-Abl-mediated phosphorylation of Rad9 induces binding of Rad9 to the antiapototic Bcl-x(L) protein. The regulation of Rad9 by c-Abl in the DNA damage response is further supported by the demonstration that the interaction between c-Abl and Rad9 contributes to DNA damage-induced apoptosis. These findings indicate that Rad9 is regulated by a c-Abl-dependent mechanism in the apoptotic response to genotoxic stress.
Insights
The c-Abl tyrosine kinase interacts with and phosphorylates the Rad9 protein, promoting cell apoptosis in response to DNA damage. This interaction is crucial for the DNA damage-induced apoptotic pathway.
Area of Science:
- Cellular Biology
- Molecular Biology
- Biochemistry
Background:
- The c-Abl tyrosine kinase is activated during the cellular apoptotic response to DNA damage.
- The precise signaling mechanisms by which c-Abl induces apoptosis remain unclear.
Purpose of the Study:
- To elucidate the molecular mechanisms underlying c-Abl's role in DNA damage-induced apoptosis.
- To investigate the interaction between c-Abl and the Rad9 cell cycle checkpoint protein.
Main Methods:
- Constitutive binding assays between c-Abl and Rad9.
- In vitro and cellular phosphorylation studies of Rad9 by c-Abl.
- Analysis of Rad9 binding to Bcl-x(L) following c-Abl phosphorylation.
Main Results:
- c-Abl constitutively binds to the mammalian Rad9 protein, specifically through its SH3 domain interacting with Rad9's C-terminal region.
- c-Abl phosphorylates Rad9 at Tyr-28, which enhances Rad9's binding to the anti-apoptotic protein Bcl-x(L).
- The interaction between c-Abl and Rad9 is shown to contribute significantly to DNA damage-induced apoptosis.
Conclusions:
- Rad9 is regulated by a c-Abl-dependent mechanism during the apoptotic response to genotoxic stress.
- c-Abl-mediated phosphorylation of Rad9 is a key step in initiating apoptosis following DNA damage.