Global Analysis of Posttranscriptional Gene Expression in Response to Sodium Arsenite

Background:Inorganic arsenic species are potent environmental toxins and causes of numerous health problems. Most studies have assumed that arsenic-induced changes in mRNA levels result from effects on gene transcription.Objectives:We evaluated the prevalence of changes in mRNA stability in response to sodium arsenite in human fibroblasts.Methods:We used microarray analyses to determine changes in steady-state mRNA levels and mRNA decay rates following 24-hr exposure to noncytotoxic concentrations of sodium arsenite, and we confirmed some of these changes using real-time reverse-transcription polymerase chain reaction (RT-PCR).Results:In arsenite-exposed cells, 186 probe set–identified transcripts were significantly increased and 167 were significantly decreased. When decay rates were analyzed after actinomycin D treatment, only 4,992 (9.1%) of probe set–identified transcripts decayed by > 25% after 4 hr. Of these, 70 were among the 353 whose steady-state levels were altered by arsenite, and of these, onl...