Regulation of early signaling and gene expression in the α-particle and bystander response of IMR-90 human fibroblasts

• Main Authors: Hei Tom K (Author), Ivanov Vladimir N (Author), Ming Lihua (Author), Ghandhi Shanaz A (Author), Amundson Sally A (Author)
• Format: Book
• Published: BMC, 2010-07-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

<p>Abstract</p> <p>Background</p> <p>The existence of a radiation bystander effect, in which non-irradiated cells respond to signals from irradiated cells, is well established. To understand early signaling and gene regulation in bystander cells, we used a bio-informatics approach, measuring global gene expression at 30 minutes and signaling pathways between 30 minutes and 4 hours after exposure to α-particles in IMR-90 fibroblasts.</p> <p>Methods</p> <p>We used whole human genome microarrays and real time quantitative PCR to measure and validate gene expression. Microarray analysis was done using BRB-Array Tools; pathway and ontology analyses were done using Ingenuity Pathway Analysis and PANTHER, respectively. We studied signaling in irradiated and bystander cells using immunoblotting and semi-quantitative image analysis.</p> <p>Results</p> <p>Gene ontology suggested signal transduction and transcriptional regulation responding 30 minutes after treatment affected cell structure, motility and adhesion, and interleukin synthesis. We measured time-dependent expression of genes controlled by the NF-κB pathway; matrix metalloproteinases 1 and 3; <it/>chemokine ligands 2, 3 and 5 and <it/>interleukins 1β, 6 and 33. There was an increased response of this set of genes 30 minutes after treatment and another wave of induction at 4 hours. We investigated AKT-GSK3β signaling and found both AKT and GSK3β are hyper-phosphorylated 30 minutes after irradiation and this effect is maintained through 4 hours. In bystander cells, a similar response was seen with a delay of 30 minutes. We proposed a network model where the observed decrease in phosphorylation of β-catenin protein after GSK3β dependent inactivation can trigger target gene expression at later times after radiation exposure</p> <p>Conclusions</p> <p>These results are the first to show that the radiation induced bystander signal induces a widespread gene expression response at 30 minutes after treatment and these changes are accompanied by modification of signaling proteins in the PI3K-AKT-GSK3β pathway.</p>

Item Description

10.1186/1755-8794-3-31
1755-8794