Molecular mechanisms of olfactory adaptation
In the mammalian nervous system, monoamines and neuropeptides are known to modulate senses, motions, emotion, and so on. These neurotransmitters are received by GPCRs (G protein coupled receptors) , and affect various effectors through heterotrimeric G proteins. Among heterotrimeric G protein α-subunits, Go, a type of Gi subfamily, is most abundantly expressed in the mammalian nervous system. In previous studies, Go knockout mice displayed a severe impairment of motor control and a hyperalgesic response. However, the physiological function of Go is still unclear.
C. elegans is attracted to a series of odorants such as benzaldehyde, which is one of the components of an apricot, almond, and other fruits. However, after continuous exposure to benzaldehyde in 15 to 60 minutes, worms stop approaching it. This is called olfactory adaptation, and considered an important mechanism to properly recognize odorants in the environment. Olfactory adaptation is observed in many animals, as human can’t sense the odorant after long exposure to it.
We found that the goa-1 (Go alpha subunit) gene, which encodes G ptotein Go, has a role in olfactory adaptation in C. elegans While previous studies reported that GOA-1 inhibits acetylcholine release from motor neurons at the neuromuscular junctions, its role in chemotaxis behavior remained to be elucidated. Therefore, we study G protein signaling pathways which antagonistically modulate olfactory adaptation, and its downstream Diacylglycerol signaling (DAG) in C. elegans, using molecular biology and genetic approaches.