New tools for targeted disruption of cholinergic synaptic transmission in Drosophila melanogaster.

ABSTRACT: Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels. The ?7 subtype of nAChRs is involved in neurological pathologies such as Parkinson's disease, Alzheimer's disease, addiction, epilepsy and autism spectrum disorders. The Drosophila melanogaster ?7 (D?7) has the closest sequence homology to the vertebrate ?7 subunit and it can form homopentameric receptors just as the vertebrate counterpart. The D?7 subunits are essential for the function of the Giant Fiber circuit, which mediates the escape response of the fly. To further characterize the receptor function, we generated different missense mutations in the D?7 nAChR's ligand binding domain. We characterized the effects of targeted expression of two UAS-constructs carrying a single mutation, D197A and Y195T, as well as a UAS-construct carrying a triple D77T, L117Q, I196P mutation in a D?7 null mutant and in a wild type background. Expression of the triple mutation was able to restore the function of the circuit in D?7 null mutants and had no disruptive effects when expressed in wild type. In contrast, both single mutations severely disrupted the synaptic transmission of D?7-dependent but not glutamatergic or gap junction dependent synapses in wild type background, and did not or only partially rescued the synaptic defects of the null mutant. These observations are consistent with the formation of hybrid receptors, consisting of D197A or Y195T subunits and wild type D?7 subunits, in which the binding of acetylcholine or acetylcholine-induced conformational changes of the D?7 receptor are altered and causes inhibition of cholinergic responses. Thus targeted expression of D197A or Y195T can be used to selectively disrupt synaptic transmission of D?7-dependent synapses in neuronal circuits. Hence, these constructs can be used as tools to study learning and memory or addiction associated behaviors by allowing the manipulation of neuronal processing in the circuits without affecting other cellular signaling.

SUBMITTER: Mejia M 

PROVIDER: S-EPMC3667824 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature