Suppression of the fat storage defect of C. elegans dbl-1/BMP signaling mutants correlates with improved survival on...

Innate immunity is a fundamental form of defense that is regulated by conserved signaling pathways. One such pathway is the DBL-1 /BMP (Bone Morphogenetic Protein) pathway, which is known to have a role in the immune response in the nematode Caenorhabditis elegans . DBL-1 /BMP signaling also regulates lipid metabolism and total fat stores. We recently demonstrated that BMP-dependent regulation of fatty acid metabolism contributes to host survival on the bacterial pathogen Serratia marcescens . We further hypothesized that suppressors of the low-fat phenotype of dbl-1 would have better survival against the bacterial pathogen S. marcescens . We isolated such suppressors in a forward genetic screen following EMS mutagenesis of dbl-1 ( wk70 ) mutants. The dbl-1 suppressor strains CS722, CS742, and CS751 were tested on S. marcescens , using dbl-1 mutant and wild-type strains as controls. We observed that the suppressor strains did indeed survive longer against S. marcescens than the dbl-1 mutants. Longer survival was correlated with a higher-fat phenotype, once again reiterating the correlation between neutral lipid levels and host-pathogen response.