RNA binding proteins coordinately control lifespan in C. elegans
Regulation of gene expression affects lifespan in Caenorhabditis elegans. While transcription factors have been extensively studied for their role in aging, less is known about how RNA binding proteins may contribute to the aging process. We recently performed a CRISPR/Cas-9 based Synthetic Genetic Interaction (CRISPR-SGI) screen in C. elegans focused on conserved neuronally-expressed RNA binding proteins, and identified many double mutants with fitness defects. In one notable interaction between the MBNL1/2 ortholog mbl-1 and the ELAVL ortholog exc-7, double mutants displayed a severely shortened lifespan (~70%). Both genes are required for regulating hundreds of transcripts and isoforms, and both play a critical role in lifespan extension through insulin signaling. Additional interactions between mbl-1 and fox-1, and exc-7 and fox-1 showed ~10% and ~20% lifespan shortening respectively, while the constituent single mutants had no effect on lifespan. We have therefore identified a trio of RNA binding proteins combinatorically required for proper lifespan in C. elegans. The mbl-1;exc-7 double mutant appears to develop into healthy young adults after which their health rapidly declines. We have used RNA seq data to investigate which RNAs may be uniquely dysregulated in the mbl-1;exc-7 double mutant. Our preliminary data has led us to hypothesize that immune gene dysregulation may play an important role in the shortened lifespan phenotype. “SMURF” assays performed to establish intestinal barrier permeability shown early “leaky” guts in the mbl-1;exc-7 double mutants, supporting our immune dysregulation hypothesis. We are currently investigating further genes of interest (GOI) identified through our RNA seq analysis, and testing whether they modulate the lifespan phenotype of mbl-1;exc-7 mutants. mbl-1, fox-1, and exc-7 are neuronally-enriched genes and we are currently conducting experiments to test whether their expression in the nervous system is the critical tissue affecting whole-worm lifespan.