Yan Li,Miaomiao Jiang,Shuang Liang,Zhiqiang Chen,Pengfei Qiang,Lu Zhang,Xiwei Zhang,Shuoye Yang
Gold nanoparticles (AuNPs) have long been considered to be one of the safest central nervous system (CNS) drug delivery carriers. However, recent studies have shown that AuNPs can affect the mitochondria–lysosome interaction in neuronal cells, although the underlying mechanism is not fully understood. The mitochondria–lysosome interaction is crucial for mitochondrial damage repair and quality control. In this study, we used PC-12 cells as a neuronal cell model to investigate the impact of AuNPs on the regulation of mitochondria–lysosome interaction. We found that AuNPs disrupt this regulation by interfering with the expression of TBC1D15, a key regulator of the mitochondria–lysosome interaction. Specifically, the expected increase in TBC1D15 expression upon mitochondrial damage was reduced with increasing AuNP concentrations. Concurrently, we observed a significant increase in the number of mitochondria and the level of the mitochondria–lysosome interaction. Additionally, the level of cellular autophagy represented by LC3B was markedly enhanced. These findings suggest that AuNPs may lead to the accumulation of mitochondrial damage by interfering with TBC1D15, resulting in neurotoxicity. This study provides important theoretical support for elucidating the mechanism of AuNP-mediated disruption of the mitochondria–lysosome interaction, which is crucial for understanding the potential risks of using AuNPs as drug delivery carriers in the central nervous system.
Background: Mitochondria–lysosome coupling and mitophagy are fundamental to mitochondrial homeostasis, yet the determinants governing this process remain incompletely defined. This study distinguished the regulatory modes of TBC1D15 and established its functional role as a downstream effector in mitochondria-linked autophagy. Methods: PC-12 and HeLa cells were treated with CCCP, gradient-concentrated AuNPs, and CQ, combined with siRNA-mediated PINK1 knockdown. Whole-cell, mitochondrial and lysosomal fractions were analyzed by immunoblotting. Results: Inter-organelle translocation of TBC1D15, rather than its total abundance, serves as the critical switch for mitochondria–lysosome homeostasis. CCCP induced a time-dependent biphasic change in TBC1D15 that persisted upon PINK1 knockdown, indicating regulation is not strictly PINK1-dependent. High-dose AuNPs trapped TBC1D15 on mitochondria and blocked lysosomal delivery via a PINK1-independent route. AuNPs exhibited biphasic concentration-dependent effects: low concentrations moderately upregulated TBC1D15, promoting adaptive organelle contacts, while millimolar concentrations caused pathological tethering. Subcellular fractionation and CQ intervention confirmed that defective lysosomal delivery underlies mitochondrial TBC1D15 accumulation upon AuNP challenge. Conclusions: This work establishes two distinct regulatory axes converging on TBC1D15. High-dose AuNPs can serve as a specific pharmacological blocker of TBC1D15 trafficking, offering therapeutic avenues for disorders characterized by impaired mitophagy.
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