The lysosome-mitochondrion crosstalk engaged in silver nanoparticles-disturbed mitochondrial homeostasis

Given their increasing industrial and biomedical applications, silver nanoparticles (AgNPs) have become widely present in the environment. However, to date, studies on their potential health risks have been far from sufficient, especially those regarding their neurotoxic effects. This study investigated the neurotoxic effects of AgNPs on neural PC-12 cells in the context of mitochondria, which play an important role in AgNP-induced cellular metabolism disturbance and even cell death. Our results show that the endocytosed AgNPs, and not extracellular Ag⁺, appear to directly determine cell fate. Importantly, endocytosed AgNPs led to mitochondrial swelling and vacuolation without direct interaction. Although mitophagy, a selective autophagy process, was invoked to rescue damaged mitochondria, it failed to function in mitochondrial degradation and recycling. Discovery of the underlying mechanism showed that the endocytosed AgNPs could directly translocate into lysosomes and then cause lysosome perturbation, which is the main factor leading to mitophagy blockade and the subsequent accumulation of defective mitochondria. After lysosomal reacidification via cyclic adenosine monophosphate (cAMP), AgNP-induced dysfunctional autolysosome formation and disturbed mitochondrial homeostasis were reversed. In summary, this study reveals that lysosome-mitochondrion crosstalk is a main mechanism for AgNP-induced neurotoxic effects, offering an inspiring perspective on the neurotoxic effects of AgNPs.