Global Analysis of Post-transcriptional Gene Expression in Arsenite-treated Human BJ Fibroblasts

Arsenic is a potent environmental toxin and a cause of numerous health problems. Most studies have assumed that arsenic-induced changes in mRNA levels result from effects on gene transcription. The influence of arsenic on post-transcriptional regulation, another important locus of gene expression control, has remained largely unexplored. To evaluate the prevalence of changes in mRNA stability in response to arsenic in human fibroblasts, we used microarray analyses to determine changes in steady state mRNA levels, and their decay rates, following 24 hour exposure to non-cytotoxic concentrations of sodium arsenite (1 µM). We conclude that arsenite modification of mRNA stability is relatively uncommon, but in some instances can result in significant changes in gene expression. Human BJ diploid foreskin fibroblasts were used in the study. The decay rates of transcripts were determined using actinomycin D to stop transcription after sodium arsenite or water treatment for 24 h. Actinomycin D was added into the culture medium at a final concentration of 5 µg/ml, and treated cells were then harvested at 0, 1, 2, 3 and 4 h for RNA extraction.