Disrupting Mitochondrial Homeostasis Via TBC1D15 Protein

Methods

PC-12 neuronal cells and HeLa epithelial cells were treated with gradient-concentration AuNPs, mitochondrial uncoupler CCCP and autophagy inhibitor chloroquine. PINK1 was knocked down via specific siRNA transfection. Western blotting was used to detect mitophagy-related proteins, and subcellular fractionation was performed to analyze the subcellular distribution of TBC1D15 between mitochondria and lysosomes.

Results: Impaired TBC1D15 translocation from mitochondria to lysosomes destroyed organelle contact and induced mitochondrial dysfunction. High-dose AuNPs retained TBC1D15 on mitochondria and interrupted its lysosomal delivery independent of PINK1, while CCCP regulated TBC1D15 abundance via canonical PINK1-dependent mitophagy. Low-concentration AuNPs upregulated TBC1D15 and promoted physiological mitochondria–lysosome interaction, showing obvious biphasic concentration-dependent bioeffects.

Conclusions: TBC1D1-mediated inter-organelle trafficking, instead of overall cellular protein level, serves as a core modulator of mitochondrial homeostasis. High-concentration AuNPs can work as a specific functional blocker of TBC1D15, offering a potential therapeutic candidate for diseases caused by PINK1-pathway deficiency-related mitochondrial damage.