Dopamine (DA) receptors belong to the large and diverse family of G-protein-coupled receptors (GPCRs). DA receptors play pivotal roles in essentially all neural activities such as cognition, memory as well as neuropsychiatric and neurodegenerative disorders. Recent work in C. elegans has shown that dopamine release in behavioral plasticity is modulated in part through
dop-2 that codes for a dopamine auto-receptor primarily expressed in the eight pre-synaptic neurons. DOP-2 is most similar in sequence to D2-like mammalian receptors with characteristic seven trans-membrane domains known to act through G-protein coupled pathways. Experiments conducted in our lab with
dop-2 loss-of-function mutants (obtained through CGC) reveal that they display an aberrant habituation to mechanosensation. In order to assign the signaling pathway for DOP-2 we examined the C. elegans expression database and noticed that DOP-2 expression overlaps with a G-subunit encoded by
gpa-14. Based on this hypothesis that dopamine auto-receptor DOP-2 might act through this identified G-subunit, we carried out a split-ubiquitin based yeast two-hybrid screen. Yeast two-hybrid results revealed that about one-third of the interacting clones were represented by
gpa-14 sequences. To demonstrate the physical coupling between auto-receptor DOP-2 and GPA-14, in-vitro pull down assays were performed. We have generated truncated DOP-2 constructs in order to characterize the specific domains of DOP-2 required for interaction with GPA-14, through in-vitro and in-vivo interaction studies. Behavioral characterization of loss-of-function mutants in
gpa-14 showed that it exhibits habituation deficits remarkably similar to
dop-2. Our interaction studies and behavior data suggest that DOP-2 signaling during C. elegans learning is mediated through GPA-14. Funds from NIH-INBRE (2P20RR-016472-10) are gratefully acknowledged.