Cdc42 plays a requisite role in dopamine transporter endocytic trafficking (896.6)

Abstract

Dopaminergic neurotransmission is essential for voluntary movement, reward and cognition, and dopamine (DA) signaling is implicated in Parkinson’s disease, addiction and schizophrenia. The presynaptic Na+/Cl‐‐dependent DA transporter (DAT) recaptures released DA, thereby temporally and spatially sculpting DAergic neurotransmission. DAT is potently inhibited by addictive (cocaine, amphetamine [AMPH]) and therapeutic (methylphenidate) psychostimulants. DAT loss‐of‐function mutations lead to infantile Parkinsonism and several DAT coding variants are associated with ADHD. Thus, intrinsic cellular mechanisms modulating DAT availability are likewise predicted to significantly impact DAergic neurotransmission. PKC activation and AMPH exposure acutely decrease DAT surface expression via robust endocytic trafficking. However, the mechanisms governing DAT membrane trafficking are not clearly defined. We recently demonstrated that 1) Rin GTPase activity is required for PKC‐stimulated DAT internalization and 2) DAT endocytic recycling relies on a dynamin/actin‐dependent mechanism. Both Rin and the actin cytoskeleton are intimately coupled to cdc42, suggesting that cdc42 activity may impart multimodal control over DAT endocytic trafficking. Here, we used small molecule cdc42 inhibitors and cdc42 mutants to test this possibility in dopaminergic cells lines and acute mouse striatal slices. Cdc42 inhibitors casin and pirl1 significantly decreased DA uptake in SK‐N‐MC cells. DAT functional losses were accompanied by decreased DAT surface expression in SK‐N‐MC cells and in mouse striatal slices. Studies using shRNA and cdc42 GTPase mutants will further define the role of cdc42 in DAT membrane trafficking.Grant Funding Source: DA035244