Poster abstracts
Poster number 45 submitted by Alfa Dhakal
Combines loss of ADARs and RDE-4 provides resistance to an opportunistic human pathogen
Alfa Dhakal (Indiana University), Heather A. Hundley (Indiana University)
Abstract:
All organisms must be able to fight infection to survive. To defend against infections, cells have equipped machinery to activate signaling pathways and secrete effector molecules. My project focuses on the role of ADARs in the pathogen response of C. elegans. ADARs are RNA binding proteins that regulate gene expression by either binding or chemically modifying RNA. Since these RBPs act on double-stranded RNA which mimics the viral genome, most ADAR studies have focused on understanding the mechanism of viral infection and how a host responds. However, the roles of ADARs in bacterial infection and host-defense mechanisms have been less studied.
Using a standard slow killing assay with Pseudomonas aeruginosa as a pathogen, we observed that C. elegans lacking ADARs have increased susceptibility to infection. Interestingly, when another dsRNA binding protein, RDE-4, is removed along with ADARs, the worms become resistant to infection. RDE-4 has been mostly studied for its role in the RNAi pathway, where it recruits Dicer to dsRNA to be cleaved into small interfering RNA (siRNA). Since the substrate for both ADARs and RDE-4 is dsRNA, the RBPs could compete for substrates, which may influence the level of small RNA and thereby influence gene expression. Behavioral assays show that adr;rde-4 animals are not resistant because they can avoid the lawn of bacteria more efficiently but have significantly lower proliferation of PA14 in the intestine. Upon looking at the gene expression changes in these animals we found no distinctive ontology. Ongoing experiments are focused on finding the tissue specific contributions of ADARs and RDE-4 in pathogen resistance using auxin inducible degron (AID). These investigations will help us understand the interaction between two different families of RNA binding proteins and how this interaction helps animals respond to infection.
Keywords: Innate immunity, ADAR, dsRNA binding protein