Novelty-induced hyperactivity and suppressed cocaine induced locomotor activation in mice lacking threonine 53 phosphorylation of dopamine transporter

• Published in: Behavioural brain research Vol. 408; p. 113267
• Main Authors: Ragu Varman, Durairaj, Subler, Mark A., Windle, Jolene J., Jayanthi, Lankupalle D., Ramamoorthy, Sammanda
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 25.06.2021
• Subjects: Affinity; Animals; Behavior; Behavior, Animal - drug effects; Cocaine; Cocaine - pharmacology; Corpus Striatum - drug effects; Corpus Striatum - metabolism; DAT-Ala53 knock-in; Disease Models, Animal; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors - pharmacology; ERK1/2; Locomotion - drug effects; MAP Kinase Signaling System; Mice; Mice, Transgenic; Phosphorylation; Phosphorylation - physiology; Threonine - metabolism; DAT-Ala53 knock-in; Affinity; ERK1/2; Phosphorylation; Cocaine; Behavior
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/j.bbr.2021.113267

•DAT-Ala53 knock-in mice are viable and display no developmental deficits.•DA-transport and the expression of DAT and TH are unaltered in the DAT-Ala53 mice.•DAT-Ala53 mice exhibit hyperactivity in novel environment.•ERK1/2 mediated DAT regulation is blunted in the DAT-Ala53 knock-in mice.•DAT-Ala53 mice exhibit reduced sensitivity to cocaine inhibition and hyperlocomotion. Dopamine (DA) transporter (DAT) is dynamically regulated by several protein kinases and the Thr53 phosphorylation of DAT (pT53-DAT) is documented in heterologous cell models and in rat brain. However, the role of endogenous pT53-DAT in living animals has never been addressed. Here we generated and studied the pT53-lacking DAT mouse model (DAT-Ala53) by CRISPR/Cas9 technology. DAT-Ala53 mice showed normal growth, body weight, body temperature, grip strength, and sucrose preference while pT53-DAT was completely absent. However, DAT-Ala53 mice showed hyperlocomotion, pronounced vertical exploratory behavior, and stereotypy in a novel environment compared to wild-type littermates (WT). DAT-Ala53 mice displayed unaltered levels of monoamines, glutamate, and GABA in the striatum compared to WT. There were also no significant differences between DAT-Ala53 mice and WT in tyrosine hydroxylase (TH) and phospho-TH levels, or in total and surface DAT levels, or in DA-transport kinetic parameters Vmax and Km. Immunohistochemical and colocalization analyses of TH and DAT in caudate-putamen and nucleus accumbens revealed no significant differences between DAT-Ala53 and WT mice. Interestingly, cocaine’s potency to inhibit striatal DA transport and cocaine-induced locomotor activation were significantly reduced in the DAT-Ala53 mice. Also, ERK1/2 inhibitors completely failed to inhibit striatal DA uptake in DAT-Ala53 mice. Collectively, our findings reveal that the mice lacking pT53-DAT display novelty-induced hyperactive phenotype despite having normal transporter protein expression, DA-transport kinetics and DA-linked markers. The results also reveal that the lack of endogenous pT53-DAT renders DAT resistant to ERK1/2 inhibition and also less susceptible to cocaine inhibition and cocaine-evoked locomotor stimulation.