Abemaciclib and Vacuolin-1 decrease aggregate-prone TDP-43 accumulation by accelerating autophagic flux.

Area of Science:

• Cell Biology
• Neuroscience
• Molecular Biology

Background:

• Autophagy is a key cellular process for degrading unwanted materials, including aggregate-prone TDP-43.
• TDP-43 aggregation is implicated in neurodegenerative diseases like amyotrophic lateral sclerosis and frontotemporal lobar degeneration.
• Abemaciclib (Abe) and vacuolin-1 (Vac) are known to induce autophagosome-lysosome structures, suggesting a role in autophagy.

Purpose of the Study:

• To investigate if Abemaciclib and vacuolin-1 accelerate autophagic flux and reduce TDP-43 accumulation.
• To elucidate the mechanism by which Abe and Vac influence autophagosome-lysosome fusion and TDP-43 degradation.

Main Methods:

• Utilized SH-SY5Y neuroblastoma cells expressing autophagic flux and lysosome markers (GFP-LC3-RFP-LC3ΔG, mCherry-LC3, LAMP1-GFP).
• Assessed autophagosome formation, lysosomal localization, and TDP-43 levels following Abe and Vac treatment.
• Employed a PI(3)P reporter assay and a VPS34 inhibitor (wortmannin) to examine pathway involvement.

Main Results:

• Abe and Vac dose-dependently reduced the GFP/RFP ratio, indicating accelerated autophagic flux.
• These treatments increased autophagosome markers colocalized with lysosomes and enhanced PI(3)P signaling on lysosomes.
• Abe and Vac treatment inhibited TDP-43 accumulation in an autophagy-dependent manner, and wortmannin blocked these effects.

Conclusions:

• Abemaciclib and vacuolin-1 promote the degradation of aggregate-prone TDP-43.
• These drugs enhance autophagy by increasing PI(3)P formation, thereby accelerating autophagosome formation and lysosome fusion.
• The findings suggest a therapeutic potential for Abe and Vac in neurodegenerative diseases linked to TDP-43 aggregation.