Biology subjects

Conklin, T.

Publications and source records attributed to Conklin, T..

2 recordsLinked to original sources

bioRxiv2023

Rit2 loss in dopaminergic neurons drives a progressive Parkinsonian phenotype

Parkinsons disease (PD) is the second most prevalent neurodegenerative disease and arises from dopamine (DA) neuron death selectively in the substantia nigra pars compacta (SNc). Rit2 is a reported PD risk allele, and recent single cell transcriptomic studies identified a major RIT2 cluster in PD DA neurons, potentially linking Rit2 expression loss to a PD patient cohort. However, it is still unknown whether Rit2 loss itself is causative for PD or PD-like symptoms. Here we report that conditional Rit2 silencing in mouse DA neurons drove motor dysfunction that occurred earlier in males than females and was rescued at early stages by either inhibiting the DA transporter (DAT) or with L-DOPA treatment. Motor dysfunction was accompanied by decreased DA release, striatal DA content, phenotypic DAergic markers, DA neurons, and DAergic terminals, with increased pSer129-alpha synuclein and pSer935-LRRK2 expression. These results provide the first evidence that Rit2 loss is causal for SNc cell death and a PD-like phenotype, and reveal key sex-specific differences in the response to Rit2 loss.

neuroscience↗

bioRxiv2021

Presynaptic Gq-coupled receptors drive biphasic dopamine transporter trafficking that modulates dopamine clearance and motor function

Extracellular dopamine (DA) levels are constrained by the presynaptic DA transporter (DAT), a major psychostimulant target. Despite its necessity for DA neurotransmission, DAT regulation in situ is poorly understood, and it is unknown whether regulated DAT trafficking impacts dopaminergic signaling and/or behaviors. Leveraging chemogenetics and conditional gene silencing, we found that activating presynaptic Gq-coupled receptors, either hM3Dq or mGluR5, drove rapid biphasic DAT membrane trafficking, with region-specific differences in ventral and dorsal striata. DAT insertion required DRD2 autoreceptors and intact retromer, whereas DAT retrieval required PKC activation and Rit2. Ex vivo voltammetry revealed that DAT trafficking impacts DA clearance. Importantly, dopaminergic mGluR5 silencing elevated surface DAT, which abolished motor learning and was rescued by inhibiting DAT. We found that presynaptic DAT trafficking is complex, multimodal, and region-specific, and identify cell autonomous mechanisms governing presynaptic DAT tone. Importantly, the findings suggest regulated DAT trafficking impacts both DA clearance and motor function.

neuroscience↗