STAT3 Inhibitor Increases α-Synuclein in PFF-Treated Astroglia Cells by Dysregulating Autophagy and Potentially Affects Exosome Biogenesis.

Astrocytes are the most abundant cells in the brain and show neuroprotective function in CNS and reactive astrocytes are characteristic in neurodegenerative diseases. The JAK2-STAT3 pathway plays a crucial role in the process of astrocyte activation. However, as a hallmark of Parkinson's disease, the change in α-syn under the influence of STAT3 inhibitor and the underlying cellular mechanisms remain elusive. Here, we show that PFF can induce an increase in α-syn in SVG p12 cells, which is further enhanced after the inhibition of STAT3. The underlying mechanisms involve the downregulation of autophagy levels and a concurrent decrease in lysosomal function after inhibition of STAT3. Additionally, we observed inhibition of STAT3 resulted in reduced exosome secretion in SVG p12 cells. This is attributed to alterations in SNARE, leading to impaired fusion between MVBs and the cell membrane, subsequently causing the accumulation of intracellular MVBs. Taken together, our data demonstrates that inhibition of STAT3 decreases both the autophagy and lysosome function, which may increase MVBs production. However, we found a potentially decreased exosome production that may be implicated with SNARE complex and need further exploration.