Study of the Intracellular Handling of Dopamine using Drosophila. Antonio Tito^1,2,3, Dongsheng Chen^1,3, Zhen Xu^1,3, Yanning Rui^1,3, Zhihua Chen^1,3, Sheng Zhang^1,2,3. 1) Center of Metabolic and Degenerative Diseases, IMM, Houston, TX; 2) Department of Neurobiology and Anatomy, GSBS, Houston, TX; 3) UT-HEALTH, Houston, TX.

   Dopamine (DA) is an important neuromodulator regulating many important behavioral roles in humans such as reward-driven behavior and motor control. Accordingly, both its intracellular packaging and release are tightly regulated in the dopaminergic neurons in the brain. Within the cell, dopamine is stored within acidic vesicles through membrane-bound Vesicular Monoamine Transporters (VMAT). These vesicles release their contents to the synaptic cleft to modulate neuronal response, while the cell surface DA transporters (DAT) re-uptake extracellular DA to terminate its action. Mis-regulation of proper DA storage mechanisms has been suspected to play a role in the selective degeneration of dopaminergic neurons in familial and sporadic cases of Parkinson's disease (PD), which is characterized by the loss of dopaminergic neurons in the substantia nigra, a brain region that controls motor output from the striatum. The cellular machineries that control DA biogenesis and function are highly conserved in Drosophila. To study the mechanisms regulating in vivo handling of DA and their potential role in PD, we have developed transgenic fly lines that allow targeted overexpression or knockdown of the fly homologues of VMAT and DAT in different fly tissues, including dopaminergic neurons. Our results show that modulating their expression level and pattern leads to a variety of animal phenotypes. Using these reagents, we are testing whether manipulation of intracellular DA handling affects the survival of dopaminergic neurons.