Acrylamide interferes with autophagy and induces apoptosis in Neuro-2a cells by interfering with TFEB-regulated lysosomal function.

Abstract

Acrylamide (ACR), a well-documented human neurotoxicant that is widely exists in starchy foods. More than 30% of human daily energy is provided by ACR-containing foods. Evidence indicated that ACR can induce apoptosis and inhibit autophagy, but the mechanisms are limited. Transcription Factor EB (TFEB) is a major transcriptional regulator of the autophagy-lysosomal biogenesis that regulates autophagy processes and cell degradation. Our study aimed to investigated the potential mechanisms of TFEB-regulated lysosomal function in ACR-caused autophagic flux inhibition and apoptosis in Neuro-2a cells. Our results found that ACR exposure inhibited the autophagic flux, as revealed by the elevated LC3-II/LC3-I and p62 levels and a notable increased autophagosomes. ACR exposure reduced the amounts of LAMP1 and mature cathepsin D and caused an accumulation of ubiquitinated proteins, which suggests lysosomal dysfunction. In addition, ACR increased cellular apoptosis via decreasing Bcl-2 expression, increasing Bax and cleaved caspase-3 expression, and raising the apoptotic rate. Interestingly, TFEB overexpression alleviated the ACR-induced lysosomal dysfunction, and then mitigated the autophagy flux inhibition and cellular apoptosis. On the other hand, TFEB knockdown exacerbated the ACR-induced lysosomal dysfunction, autophagy flux inhibition, and cellular apoptosis. These findings strongly suggested that TFEB- regulated lysosomal function is responsible for ACR-caused autophagic flux inhibition and apoptosis in Neuro-2a cells. The present study hopes to explore new sensitive indicators in the mechanism of ACR neurotoxicity and thus provide new targets for the prevention and treatment of ACR intoxication.