Comparison of the abundance of 10 radiation‐induced proteins with their differential gene expression in L929 cells

Abstract

Purpose: To determine whether radiation‐induced changes in protein abundance can be correlated with their differential gene expression in a murine fibroblast L929 cell line.

Materials and methods: L929 cells were irradiated with 6 Gy. Cell lysates were collected at different points in time (20 min, 12, 24, 36, 48 and 72 h). The extracted proteins were separated by two‐dimensional gel electrophoresis and quantified using computerized image analysis. Proteins exhibiting a differential expression equal to or more than twofold were identified by mass spectrometry following trypsin digestion. From these, 10 proteins characterized by large changes of radiation‐induced abundance were selected in order to measure their corresponding gene expression using RTQ‐PCR (real‐time quantitative polymerase chain reaction).

Results: Up to 15‐fold changes in the abundance of these 10 proteins were associated with no detectable changes more than twofold on the gene expression level. However, one gene (VEGF‐D) showed a significant (p=0.005) up‐regulation (1.8‐fold).

Conclusions: Deducing protein abundance from mRNA expression levels and vice versa appears to be of limited use. Furthermore, examination of transcriptional and translational changes provides different but complementary information.