Development of gene expression signatures for senecionine exposure

Senecionine is among the most well-studied pyrrolizidine alkaloids, which have caused intense and lasting attention for their significant hepatotoxicity. To develop gene expression approach to senecionine exposure, we have employed whole genome microarray expression profiling as a discovery platform to identify genes with the potential to be biomarkers after senecionine exposure. Rat liver tissues after 36 h of senecionine treatment (i.g., 35 mg/kg body weight) were collected and analyzed comparing with control samples (i.g., sodium chloride solution). Differentially expressed genes were identified through Fold-change filtering and subjected to GO term using gene ontology project (http://www.geneontology.org/) to uncover the co-expression network on the basis of biological process and molecular function. By setting the fold change at ≥ 2 and p value ≤0.05, 46 down-regulated signaling pathways and 50 up-regulated pathways were found, including bile secretion, primary bile acid biosynthesis, and ABC transporters. Expression of 13 genes referred to bile acids metabolism was quantified from the same tissue samples by real-time PCR, confirming senecionine exposure after 36 h could result in compromised bile acid homeostasis. Senecionine exposure induced gene expression in rat liver was measured at 36 h after exposure to that of control sample. Three tissue samples from each group were pooled as a mixture. And two independent experiments were performed (control and 36 h after senecionine exposure).