Parkinson’s disease (PD) is primarily a nonfamilial, age-related disorder caused by α-synuclein accumulation and the progressive loss of dopamine neurons in the substantia nigra pars compacta (SNc). GPCR-cAMP signaling has been linked to a reduction in human PD incidence and α-synuclein expression. Neuronal cAMP levels are controlled by GPCRs coupled to Gs or Gi/o, which increase or decrease cAMP, respectively. Regulator of G protein signaling 6 (RGS6) powerfully inhibits Gi/o signaling. Therefore, we hypothesized that RGS6 suppresses D2 autoreceptor-Gi/o signaling in SNc dopamine neurons promoting neuronal survival and reducing α-synuclein expression. Here, we provide potentially novel evidence that RGS6 critically suppresses late-age-onset SNc dopamine neuron loss and α-synuclein accumulation. RGS6 is restrictively expressed in human SNc dopamine neurons and, despite their loss in PD, all surviving neurons express RGS6. RGS6–/– mice exhibit hyperactive D2 autoreceptors with reduced cAMP signaling in SNc dopamine neurons. Importantly, RGS6–/– mice recapitulate key sporadic PD hallmarks, including SNc dopamine neuron loss, reduced nigrostriatal dopamine, motor deficits, and α-synuclein accumulation. To our knowledge, Rgs6 is the only gene whose loss phenocopies these features of human PD. Therefore, RGS6 is a key regulator of D2R-Gi/o signaling in SNc dopamine neurons, protecting against PD neurodegeneration and α-synuclein accumulation.
Zili Luo, Katelin E. Ahlers-Dannen, Mackenzie M. Spicer, Jianqi Yang, Stephanie Alberico, Hanna E. Stevens, Nandakumar S. Narayanan, Rory A. Fisher
The Editorial Board will only consider comments that are deemed relevant and of interest to readers. The Journal will not post data that have not been subjected to peer review; or a comment that is essentially a reiteration of another comment.