Cyclin-dependent kinase 5 activity modulates constitutive and substrate Dopamine Transporter cell surface expression: implications in Attention-Deficit Hyperactivity Disorder ?ADHD-

QUASSOLLO GONZALO; PAGLINI GABRIELA; FERNÁNDEZ GUILLERMO

Buenos Aires

Congreso; 2nd FALAN Congress (Federación de Asociaciones Latinoamericanas y del Caribe de Neurociencias); 2016

FALAN

Cyclin-dependent kinase 5 activity modulates constitutive and substrate Dopamine Transporter cell surface expression: implications in Attention-Deficit Hyperactivity Disorder ?ADHD-Guillermo Fernández, Gonzalo Quasollo and M. Gabriela Paglini.Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina.ADHD is a neurodevelopmental condition characterized by atypical levels of inattention, hyperactivity and impulsivity. We have shown that transgenic mice lacking p35 protein (p35KO), activator of Cyclin dependent kinase 5 (Cdk5) exhibit behaviors resembling those described in animal models of ADHD. P35KO mice show hyperactivity, less anxiety-like behaviors, elevated Striatal Dopamine (DA) synthesis and reduced DA turnover, that are reverted by Methylphenidate and d-Amphetamine (Amph). Although we have shown that p35KO mice have an altered dopaminergic system, the Dopamine Transporter (DAT) contribution to these mice phenotypes still remains unknown. Therefore, we assessed DAT expression in Striatum of p35KO mice and the consequences of Cdk5 loss activity on DAT trafficking in N2a cell culture. Biochemical analyses on Striatum extracts showed no differences in DAT levels of p35KO mice compared with WT. In order to evaluate Cdk5 regulation of DAT internalization, we inhibited Cdk5 activity with small interference RNA-Cdk5 and Roscovitine (specific Cdk5 inhibitor) in DAT transfected N2a cells. Immunofluorescence analysis showed that Amph (10 uM) increased DAT localization in early and recycling endosomes compartments of N2a cells. On the other hand, Cdk5 inhibition decreased DAT cell surface expression and Amph enhanced even more DAT internalization. These results suggest that Cdk5 activity modulates DAT trafficking to the plasma membrane and its superficial levels.