PT109B, a Multikinase Inhibitor, Converts Astrocytes into Dopaminergic Neurons and Alleviates Parkinson's Disease in Mice

Background Parkinson’s disease (PD) is characterized by the progressive loss of dopaminergic neurons (DANs), leading to motor dysfunction, while current treatments fail to restore neuronal loss. Reprogramming astrocytes into induced DANs by small molecules offers a promising therapeutic strategy, but existing methods face challenges including low efficiency and complex mechanisms. PT109B, a novel multi-kinase inhibitor, has demonstrated neurogenic and synaptogenic potential in neural progenitor cells, as well as glioblastoma differentiation capacity, yet its ability to directly convert astrocytes into functional DANs and its therapeutic effects in PD remain unclear. Methods Primary rat midbrain astrocytes were treated with 10 µM PT109B to evaluate reprogramming efficiency via immunofluorescence (GFAP, MAP2, NeuN, TH, DAT) and electrophysiological recordings. RNA sequencing was performed at 1.5, 3, and 6 hours post-treatment to assess transcriptional changes. In vivo, PT109B (100 mg/kg) was administered orally for 12 weeks in 6-OHDA-induced PD mice, with astrocytes labeled by AAV5-GFAP-EGFP. Behavioral tests (apomorphine rotation, pole test, rotarod, and open field), retrograde tracing, and immunohistochemistry were conducted to evaluate therapeutic effects. Results PT109B initiated astrocyte-to-neuron conversion as early as 3 hours, yielding 20% TH⁺ dopaminergic neurons by 2 weeks in vitro, with mature electrophysiological properties for action potentials, sodium currents and sustained dopamine release (> 3 months). Mechanistically, PT109B drove this conversion through cell cycle arrest, astrocytic activation, and upregulation of key basic Helix-Loop-Helix (b-HLH) transcription factors (NeuroD1, Ascl1, Ngn2). In vivo, oral administration of PT109B in a 6-OHDA-induced PD mouse model exhibited significant therapeutic efficacy by reprogramming astrocytes to functional neurons in the striatum, leading to improved motor functions. Conclusions PT109B efficiently converts astrocytes into functional induced DANs through rapid reprogramming and ameliorates PD-related pathology and motor deficits, presenting a safe and effective single-molecule therapeutic strategy for PD.