Habibeh Khoshbouei, Ph.D.
Department of Neuroscience (Joint Appointment in Department of Psychiatry)
University of Florida
1149 Newell Drive
PO Box 100244
Gainesville, FL 32611-0244
Office Phone: (352) 273-8115
Lab Phone: (352) 273-8739
Lab Members: Khoshbouei Lab
Lab Website: http://www.khoshboueilab.com/
Advisor: Dr. Morteza Raflee
|University of Tehran
Advisor: Dr. David Morilak
|University of Texas
San Antonio, Texas
|University of Texas
San Antonio, Texas
Molecular Physiology & Biophysics
Key Words: Neural mechanisms of addiction; Methamphetamine and related drugs; Dopamine transporters; Psychostimulant; Neurotransmission; Cellular neuroscience;Alpha-synuclein; Cellular mechanism of Parkinson’s-like pathologies
Projects in our laboratory are focused on the identification of novel mechanisms involved in regulation of dopamine neurotransmission in the brain. In particular we are interested in the regulation of dopamine transporter (DAT) an integral membrane protein vital for regulation of synaptic dopamine. Work in our laboratory is devoted to understanding the details of DAT regulation, trafficking, the pharmacological modulation of the transporter and how this is all integrated into the broader context of normal dopamine signaling and the pathogenesis of addiction, neurological and neuropsychiatric disorders.
Research Focus & Aims:
Research Project 1: α-synuclein regulation of dopamine transporter
Recent work in various disease models has begun to emphasize the significance of presynaptic dysfunction as an early event that occurs before manifestation of neurological disorders. An increasing number of proteins have been identified that interact with different domains of DAT and regulate the biology of the transporter. These interactions suggest that the synaptic distribution, targeting, compartmentalization, trafficking and functional properties of DAT can be regulated via interacting proteins. α-Synuclein is a 140-amino acid protein that forms a stable complex with DAT and is linked to the pathogenesis of neurodegenerative disease. To elucidate the potential functional consequences of DAT/α-synuclein interaction, we explored α-synuclein modulation of DAT activity in midbrain dopaminergic neurons obtained from TH::RFP mice, immortalized DA neurons, and a heterologous system expressing DAT. Our findings are consistent with the interpretation that DAT/α-synuclein interaction at the cell surface results in a DAT-dependent, Na+-insensitive, Cl-sensitive inward current with a decrease in substrate uptake, suggesting that DAT/α-synuclein interaction can modulate dopamine transmission and thus neuronal function.
Research Project 2: Psychostimulants regulation of DAT activity
The psychostimulants d-amphetamine (AMPH) and methamphetamine (METH) release excess dopamine (DA) into the synaptic clefts of dopaminergic neurons. Abnormal DA release is thought to occur by reverse transport through the DA transporter (DAT), and it is believed to underlie the severe behavioral effects of these drugs. Here we compare structurally similar AMPH and METH on DAT function in a heterologous expression system and in an animal model. In the in vitro expression system, DAT-mediated whole-cell currents were greater for METH stimulation than for AMPH. At the same voltage and concentration, METH released five times more DA than AMPH and did so at physiological membrane potentials. At maximally effective concentrations, METH released twice as much [Ca(2+)](i) from internal stores compared with AMPH. Finally, in the rat nucleus accumbens, in vivo voltammetry showed that systemic application of METH inhibited DAT-mediated DA clearance more efficiently than AMPH, resulting in excess external DA. Together, these data demonstrate that METH has a stronger effect on DAT-mediated cell physiology than AMPH, which may contribute to the euphoric and addictive properties of METH compared with AMPH.
Research Project 3: Sigma-1R regulation of Dopamine transporter
Our recent findings suggest that Sigma-1R interacts with the dopamine transporter and methamphetamine exposure increases the frequency of this interaction.
Research Project 4: Membrane localization of dopamine transporter
Though the trafficking of DAT to and away form the surface membrane has been studied extensively, it is unknown whether or not changes in the membrane potential also can regulate the trafficking of DAT. Our simultaneous patch-clamp and Total Internal Reflection Fluorescence (TIRF) confocal microscopy suggest that DAT changes in the membrane potential regulates the trafficking of Dopamine transporter. We found that membrane hyperpolarization increases YFP-DAT level at the membrane. The hyperpolarization-induced increase in surface DAT level is paralleled by an increase in DAT-mediated inward current. Currently we are examining the hypothesis that changes in the membrane potential regulate the trafficking of DAT to and from the cell surface membrane in the DA neurons.