Effects of ccf-1 RNAi on C. elegans response to cadmium and acrylamide

In a genome-wide RNAi screen to identify activators of numr-1, a cadmium responsive gene involved in RNA splicing regulation, we isolated ccf-1 as a gene that is required for cadmium-induced numr-1 activation. The ccf-1 gene encodes a deadenylase within the CCR4-NOT complex that generally serves to suppress gene expression by initiating mRNA degradation. However, a role for ccf-1 as a positive regulator of stress-induced gene expression remains to be characterized. Silencing of ccf-1 inhibits various classes of cadmium-inducible genes including several glutathione-s-transferase (gst) and heat shock protein genes. RNAi knockdown of ccf-1 significantly reduces lifespan and decreases survival in cadmium, implicating a role for ccf-1 in aging and stress protection. The ccf-1 gene is also required for resistance against acrylamide with RNAi depletion of ccf-1 inhibiting acrylamide-induced gst induction, decreasing survival in acrylamide stress, and increasing C. elegans sensitivity to acrylamide-induced neurodegeneration. Using RNA-sequencing, we observed that ccf-1 regulates ~28-35% of all genes induced by cadmium (500 out of 1802 DEG) or acrylamide (296 out of 851 DEG) by >2-fold. Clustering analysis of ccf-1 dependent cadmium or acrylamide up-regulated genes indicate significant enrichment to glutathione and cytochrome P450 metabolism, suggesting a central role for ccf-1 in regulating antioxidant defense across different stressors. Using a CCF-1::GFP translational reporter, we find that CCF-1 is broadly expressed in the intestine, muscle, and hypodemis. Interestingly, CCF-1::GFP strongly localizes to the intestinal nuclei, implicating a potential nuclear role for CCF-1 in transcriptional regulation that is distinct for its deadenylase function in the cytoplasm Total RNA was prepared from gravid young adult Caenorhabditis elegans with three biological replicates per group and sent to NovoGene for PE150 sequencing. Sequencing library were constructured with oligo-dT enrichment. Gene expression data were analyzed by DEGSeq.