Hamilton, P J2; Campbell, N G3; Sharma, S3; Erreger, K3; Hansen, Freja Herborg4; Saunders, C3; Belovich, A N3; Sahai, M A3; Cook, E H3; Gether, U4; McHaourab, H S3; Matthies, H J G3; Sutcliffe, J S3; Galli, A3
1 Neuropharm and Genetics Lab, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Københavns Universitet2 Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, TN, USA.3 unknown4 Neuropharm and Genetics Lab, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Københavns Universitet
De novo genetic variation is an important class of risk factors for autism spectrum disorder (ASD). Recently, whole-exome sequencing of ASD families has identified a novel de novo missense mutation in the human dopamine (DA) transporter (hDAT) gene, which results in a Thr to Met substitution at site 356 (hDAT T356M). The dopamine transporter (DAT) is a presynaptic membrane protein that regulates dopaminergic tone in the central nervous system by mediating the high-affinity reuptake of synaptically released DA, making it a crucial regulator of DA homeostasis. Here, we report the first functional, structural and behavioral characterization of an ASD-associated de novo mutation in the hDAT. We demonstrate that the hDAT T356M displays anomalous function, characterized as a persistent reverse transport of DA (substrate efflux). Importantly, in the bacterial homolog leucine transporter, substitution of A289 (the homologous site to T356) with a Met promotes an outward-facing conformation upon substrate binding. In the substrate-bound state, an outward-facing transporter conformation is required for substrate efflux. In Drosophila melanogaster, the expression of hDAT T356M in DA neurons-lacking Drosophila DAT leads to hyperlocomotion, a trait associated with DA dysfunction and ASD. Taken together, our findings demonstrate that alterations in DA homeostasis, mediated by aberrant DAT function, may confer risk for ASD and related neuropsychiatric conditions.
Molecular Psychiatry, 2013, Vol 18, Issue 12, p. 1315-23
Animals; Child Development Disorders, Pervasive; Child, Preschool; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dopaminergic Neurons; Drosophila melanogaster; Homeostasis; Humans; Male; Motor Activity; Mutation, Missense; Risk Factors