Trans-synaptic optogenetic control of user-defined pre- and post-synaptic partners

National Institute Of Mental Health

Investigators

Abstract

Our initial platform for trans-OptoGi employs the amphibian neuropeptide maximakinin, a high affinity agonist to bradykinin 2 receptors, engineered to be optically-gated with a circularly permutated LOV-2 domain and tethered for exposure to the extracellular space. Bradykinin 2 receptors are in large part absent in the brain and provide a suitable GPCR that can be expressed virally and provide a substrate for LOV2-maximakinin to act on in the presence of blue light. In the past year, our collaborators have generated a bradykinin 2 receptor chimera whose intracellular loops have been replaced with those pertaining to the mu-opioid receptor to enable this receptor to solely signal through inhibitory Gi/o G-protein second messengers. This modification has been motivated by our observation that wild-type bradykinin 2 receptor signaling through both excitatory Gq and inhibitory Gi/o G-proteins presented an issue in regulating synaptic transmission in preliminary studies. Our studies have demonstrated that bradykinin 2 – mu-opioid receptor chimeras are potent inhibitors of neurotransmitter release at both excitatory and inhibitory synapses. Further, our preliminary results suggest that LOV2-maximakinin can be optically unmasked to suppress pathway-specific inputs. Our collaborator has also been generating additional constructs consisting of endogenous opioid peptides containing circularly-permutated LOV2 domain for manipulation of endogenous opioid receptors on afferents innervating user-defined post-synaptic cells.