C. elegans Nuclear Hormone Receptor NHR-49 promotes attractive chemotaxis independently of its role in fatty acid metabolism

C. elegans, a small nematode worm, navigates its environment by sensing and adapting to various environmental cues. One such receptor, NHR-49, is crucial for lipid metabolism, stress resistance, pathogen defense, and longevity. It has also been linked to avoidance behaviors and memory formation, specifically through its involvement in fatty acid desaturation and oxidation.

However, the specific role of NHR-49 in neuronal signaling and behavior has yet to be fully understood. Researchers have now discovered that NHR-49 plays a distinct role in AWA neuron-mediated attractive chemotaxis. This ability allows the worm to be drawn towards certain compounds, such as diacetyl and pyrazine, which are detected by AWA neurons. Importantly, NHR-49's influence on chemistry is independent of its role in fatty acid metabolism.

The study found that supplementation with unsaturated fatty acids and analyzing genes involved in fatty acid desaturation and beta-oxidation did not impact attractive chemotaxis. This suggests that NHR-49 can independently mediate the movement towards attractive compounds. Furthermore, researchers found that expressing NHR-49 in neurons or body wall muscle could restore chemotaxis, while its depletion in neurons alone led to chemotaxis defects.

Interestingly, NHR-49 mutants also exhibited problems with another behavior: their response and habituation to mechanical stimuli. Overall, this research unveils new functions for NHR-49 in sensory responses and non-associative learning. These functions, however, are separate from its established roles in aversive behaviors and memory, as well as its well-known role in lipid metabolism.