Olfactory learning modulates the expression of molecular chaperones in C. elegans

Learning, a process by which animals modify their behavior as a result of experience, allows organisms to synthesize information from their surroundings to predict danger. Here we show that prior encounter with the odor of pathogenic bacteria not only enhances the ability of C. elegans to avoid the pathogen, but also systemically primes the transcription factor, Heat Shock Factor 1 (HSF-1) to increase molecular chaperone expression upon subsequent encounter with the pathogen by promoting its localization to RNA polymerase II enriched nuclear loci. HSF1-dependent chaperone expression ensues, however, only if and when animals encounter the pathogen. This learning-dependent enhancement of chaperone expression requires serotonin. Thus, learning equips C. elegans to better survive environmental dangers by pre-emptively and specifically initiating transcriptional mechanisms throughout the organism to maintain homeostasis. These studies provide one plausible basis for the protective role of environmental enrichment in disease.