Modulation of calmodulin by UV and X-rays in primary human endothelial cell cultures

Abstract

Purpose : Previous studies by the present authors and others have shown that the expression of many genes is modulated by radiation. The purpose of this study is to identify additional genes that are affected by UV and X-radiation. Identification of specific genes affected by radiation may allow the determination of pathways important in radiation responses as well as an examination of transcriptional elements that are involved in the process. Materials and methods : A modified differential display approach coupled with sequencing was used to identify genes that are modulated in response to UV and ionizing radiation, and Northern blot analysis was used to confirm specific gene modulation. Results : Treatment of human primary umbilical vein endothelial cells with UV radiation resulted in the differential expression of several genes. Sequencing of the bands revealed that one of these was calmodulin. There was a 30% reduction in accumulation of calmodulin-specific mRNA 1h post UV exposure, and a 50% decrease 3h after treatment. X-rays also repressed accumulation of calmodium mRNA. Radiation exposure of HeLa cells also resulted in a decrease in expression of this gene. Conclusions : UV and ionizing radiations cause a decrease in accumulation of calmodulin transcripts in the first 1-3 h following exposure. Repression of calmodium mRNA levels may be one mechanism of stress-induced intracellular Ca 2+ modulation.