Toolbox/Lecture 10

Gal4 inhibition of neurotransmission
The Gal4/UAS system is used for targeted gene expression in Drosophila as well as other model organisms. Gal4 is a transcription factor that does not activate native Drosophila genes but activates the expression of genes that are under the control of UAS. Gal4 can be used neurobiologically to selectively inhibit the neurotransmission of a subset of neurons. To do this, a Gal4-encoding gene is placed between some gene, present in a certain subset of neurons, and the promoter for this gene. In this way, whenever the gene is expressed, Gal4 is expressed. Next, UAS is placed next to a transgene that is incorporated into the neuronal DNA and that codes for the shibire protein. Gal4 will bind to UAS, activating the expression of the transgene’s shibire protein product. When exposed to temperatures higher than a permissive temperature, the shibire protein is disrupted and results in the blockage of synaptic signaling. Thus by manipulating the temperature a subset of neurons can be turned on and off.