BMP-dependent mobilization of fatty acid metabolism promotes Caenorhabditis elegans survival on a bacterial pathogen
The Bone Morphogenetic Proteins (BMPs) are secreted peptide ligands of the Transforming Growth Factor beta (TGF-ß) family, initially identified for their roles in development and differentiation across animal species. They are now increasingly recognized for their roles in physiology and infectious disease. In the nematode Caenorhabditis elegans, the BMP ligand DBL-1 controls fat metabolism and immune response, in addition to its roles in body size regulation and development. DBL-1 regulates classical aspects of innate immunity, including the induction of anti-microbial peptides. We theorized that BMP-dependent regulation of fat metabolism could also promote resilience against microbial pathogens. We found that exposure to a bacterial pathogen alters total fat stores, lipid droplet dynamics, and lipid metabolism gene expression in a BMP-dependent manner. We further showed that fatty acid desaturation plays a major role in survival on a bacterial pathogen, while fatty acid ß-oxidation plays a more minor role. We conclude that C. elegans mobilizes fatty acid metabolism in response to pathogen exposure to promote survival. Our investigation provides a framework to study potential metabolic interventions that could support therapeutics that are complementary to antibiotic strategies. Overall design: RNA-seq profiling of C. elegans wildtype and dbl-1 mutants after 24 hour exposure to either control Escherichia coli bacteria or pathogenic Serratia marcescens