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 ELAVL ortholog
exc-7 and the MBNL1/2 ortholog
mbl-1, double mutants displayed a severely shortened lifespan (~70%). Both genes are required for regulating hundreds of transcripts and isoforms. The
exc-7;
mbl-1 double mutant appears to develop into healthy young adults after which their health rapidly declines.
exc-7 and
mbl-1 are both neuronally-enriched genes. Initial experiments with
mbl-1 tissue specific re-expression have shown partial rescue of the lifespan phenotype with re-expression in the nervous or intestinal tissues of the double mutant but not muscle tissue. Shortly we will be conducting experiments to test whether
exc-7 expression in the nervous system is the critical tissue affecting whole-worm lifespan seen in the
exc-7;
mbl-1 double mutant. We have used RNA seq data to investigate which RNAs may be uniquely dysregulated in the
exc-7;
mbl-1 double mutant. We identified eight uniquely dysregulated genes and have tested six out of eight of these genes in order to investigate their effects within the double mutant. We have identified one gene that appears to partially rescue the lifespan phenotype.
nhx-6, a predicted Na/H exchanger, which was identified from our RNA Seq data contributes to the phenotype and is expressed in the intestine.
nhx-6 partially rescues a number of
exc-7;
mbl-1 phenotypes, including intestinal permeability, defecation cycle length, and pharyngeal pumping. We are currently investigating further genes of interest identified through our RNA seq analysis, and testing whether they modulate the lifespan phenotype of
exc-7;
mbl-1 mutants.