Striatal Dopamine Transporter Function Is Facilitated by Converging Biology of α-Synuclein and Cholesterol

Abstract

Striatal dopamine transporters (DAT) powerfully regulate dopamine signaling, and can contribute risk to degeneration in Parkinson’s disease (PD). DATs can interact with the neuronal protein α-synuclein, which is associated with the etiology and molecular pathology of idiopathic and familial PD. Here, we tested whether DAT function in governing dopamine (DA) uptake and release is modified in a human-α-synuclein-overexpressing (SNCA-OVX) transgenic mouse model of early PD. Using fast-scan cyclic voltammetry (FCV) in ex vivo acute striatal slices to detect DA release, and biochemical assays, we show that several aspects of DAT function are promoted in SNCA-OVX mice. Compared to background control α-synuclein-null mice (Snca-null), the SNCA-OVX mice have elevated DA uptake rates, and more pronounced effects of DAT inhibitors on evoked extracellular DA concentrations ([DA]o) and on short-term plasticity (STP) in DA release, indicating DATs play a greater role in limiting DA release and in driving STP. We found that DAT membrane levels and radioligand binding sites correlated with α-synuclein level. Furthermore, DAT function in Snca-null and SNCA-OVX mice could also be promoted by applying cholesterol, and using Tof-SIMS we found genotype-differences in striatal lipids, with lower striatal cholesterol in SNCA-OVX mice. An inhibitor of cholesterol efflux transporter ABCA1 or a cholesterol chelator in SNCA-OVX mice reduced the effects of DAT-inhibitors on evoked [DA]o. Together these data indicate that human α-synuclein in a mouse model of PD promotes striatal DAT function, in a manner supported by extracellular cholesterol, suggesting converging biology of α-synuclein and cholesterol that regulates DAT function and could impact DA function and PD pathophysiology.

Global Cerebral Ischemia in Male Long Evans Rats Impairs Dopaminergic/ΔFosB Signalling in the Mesocorticolimbic Pathway Without Altering Delay Discounting Rates

“…Negative controls (without primary antibody) ensured secondary antibody specificity and pilot studies determined optimal primary antibody concentrations. Staining and expression was similar to previous studies (See Larson and Ariano, 1995 for DRD 2 ; Sun et al, 2020 for ΔFosB; and Threlfell et al, 2021 for DAT). For DRD 2 , antigen retrieval was performed prior to blocking.…”

Identification of Hypothalamic Long Noncoding RNAs Associated with Hypertension and the Behavior/Neurological Phenotype of Hypertensive ISIAH Rats

“…Some studies indicate that the cholesterol content of brain membranes is linked with DAT-mediated dopamine neurotransmission [ 81 ]. Recently, cholesterol transporter ABCA1 was reported to be involved in the control over DAT activity [ 82 ]. It should be emphasized that the expression correlation between Snhg4 and Abca1 is one of the most statistically significant in our study.…”

Applying a Fast-Scan Cyclic Voltammetry to Explore Dopamine Dynamics in Animal Models of Neuropsychiatric Disorders

“…Furthermore, in two alpha-synuclein deficient mouse lines, one carrying a spontaneous deletion of alpha-synuclein locus and the other a transgenic alpha-synuclein knockout, stimulated dopamine overflow was higher with a concomitant decrease in dopamine reuptake in the dorsal striatum [86]. Furthermore, human alphasynuclein-overexpressing transgenic mice, a model of early PD, demonstrate elevated dopamine uptake rates and more pronounced effects of DAT inhibitors on evoked extracellular dopamine concentrations [88]. Utilizing ex vivo slice FSCV it has been demonstrated that alpha-synuclein promotes striatal DAT function through mechanisms dependent on extracellular cholesterol, thus suggesting converging biology of alpha-synuclein and cholesterol to regulate DAT that potentially promotes vulnerability to neuronal degeneration in PD [88].…”

“…Furthermore, human alphasynuclein-overexpressing transgenic mice, a model of early PD, demonstrate elevated dopamine uptake rates and more pronounced effects of DAT inhibitors on evoked extracellular dopamine concentrations [88]. Utilizing ex vivo slice FSCV it has been demonstrated that alpha-synuclein promotes striatal DAT function through mechanisms dependent on extracellular cholesterol, thus suggesting converging biology of alpha-synuclein and cholesterol to regulate DAT that potentially promotes vulnerability to neuronal degeneration in PD [88]. In a human alpha-synuclein-expressing mouse model of PD with macroautophagic failure in dopamine neurons, an increase in evoked extracellular concentrations of dopamine, reduction of dopamine uptake, and relieved paired-stimulus depression was found [89].…”