Dynamic Regulation at the Neuronal Plasma Membrane: Novel Endocytic Mechanisms Control Anesthetic-Activated Potassium Channels and Amphetamine-Sensitive Dopamine Transporters: A Dissertation

Abstract

Endocytic trafficking dynamically regulates neuronal plasma membrane protein presentation and activity, and plays a central role in excitability and plasticity. Over the course of my dissertation research I investigated endocytic mechanisms regulating two neuronal membrane proteins: the anesthetic-activated potassium leak channel, KCNK3, as well as the psychostimulant-sensitive dopamine transporter (DAT). My results indicate that KCNK3 internalizes in response to Protein Kinase C (PKC) activation, using a novel pathway that requires the phosphoserine binding protein, 14-3-3β, and demonstrates for the first time regulated KCNK3 channel trafficking in neurons. Additionally, PKC-mediated KCNK3 trafficking requires a non-canonical endocytic motif, which is shared exclusively between KCNK3 and sodium-dependent neurotransmitter transporters, such as DAT. DAT trafficking studies in intact ex vivo adult striatal slices indicate that DAT endocytic trafficking has both dynamin-dependent and –independent components. Moreover, DAT segregates into two populations at the neuronal plasma membrane: trafficking-competent and -incompetent. Taken together, these results demonstrate that novel, non-classical endocytic mechanisms dynamically control the plasma membrane presentation of these two important neuronal proteins.