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Impaired regulation of nuclear factor-kappaB results in apoptosis induced by gamma radiation
1Department of Radiation Medicine, Georgetown University Medical Center, Washington, DC 20007, USA.
Abstract:
Recent studies have shown that activation of nuclear factor-kappaB (NF-kappaB) is critical for cell survival. Cells from patients with ataxia telangiectasia (AT) have an impaired NF-kappaB response to ionizing radiation. AT cells also exhibit inappropriate regulation of apoptosis. We report here that expression of a dominant negative form of IkappaB-alpha, an inhibitor of NF-kappaB, protects AT fibroblasts from apoptosis induced by gamma radiation, but it enhances apoptosis in normal fibroblasts. Furthermore, the process leading to apoptosis may involve caspase 3-mediated cleavage of IkappaB-alpha. These data suggest that regulation of NF-kappaB may play an important role in programmed cell death induced by DNA damage in AT cells.
Insights
Nuclear factor-kappaB (NF-kappaB) pathway activation is crucial for cell survival. Inhibiting NF-kappaB protects ataxia telangiectasia (AT) cells from radiation-induced apoptosis, unlike in normal cells.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Nuclear factor-kappaB (NF-kappaB) activation is vital for cell survival.
- Ataxia telangiectasia (AT) cells display defective NF-kappaB signaling and aberrant apoptosis regulation following ionizing radiation exposure.
- NF-kappaB is a key transcription factor regulating genes involved in cell survival, proliferation, and inflammation.
Purpose of the Study:
- To investigate the role of NF-kappaB signaling in radiation-induced apoptosis in Ataxia Telangiectasia (AT) cells.
- To determine if modulating NF-kappaB activity can alter the apoptotic response of AT cells to gamma radiation.
- To explore the potential involvement of caspase 3 in the regulation of NF-kappaB during DNA damage-induced apoptosis.
Main Methods:
- Utilized dominant-negative IkappaB-alpha to inhibit NF-kappaB activity in AT and normal fibroblasts.
- Exposed cells to gamma radiation to induce DNA damage and apoptosis.
- Assessed cell survival and apoptosis rates using standard cell biology techniques.
- Investigated the cleavage of IkappaB-alpha by caspase 3.
Main Results:
- Expression of dominant-negative IkappaB-alpha protected AT fibroblasts from gamma radiation-induced apoptosis.
- Conversely, dominant-negative IkappaB-alpha enhanced apoptosis in normal fibroblasts exposed to gamma radiation.
- Evidence suggests that caspase 3 may mediate the cleavage of IkappaB-alpha, linking it to the apoptotic process.
Conclusions:
- NF-kappaB pathway regulation is critically involved in DNA damage-induced programmed cell death in AT cells.
- Targeting NF-kappaB signaling may offer therapeutic strategies for managing radiation sensitivity in AT patients.
- The interplay between NF-kappaB, apoptosis, and DNA damage response pathways is complex and cell-type specific.