Tunicamycin-induced ER stress promotes inflammation in SH-SY5Y cells through ROS-NF-κB-SIRT1 pathway

The accumulation of unfolded and misfolded proteins within the endoplasmic reticulum (ER) causes ER stress, leading to various physiological and pathological conditions. The cell activates unfolded protein response (UPR), an adaptive mechanism, to maintain the ER proteostasis. Neuronal ER stress can contribute to various neurodegenerative diseases. This study aims to investigate the effect of tunicamycin-induced ER stress on neuronal inflammation and the molecular mechanism involved.

To study the ER stress-associated neuronal inflammation in vitro, we used tunicamycin-induced SH-SY5Y cell lines as the model system. PCR, ELISA, and immunoblot analysis were used to study mRNA and protein expressions. Reactive oxygen species (ROS) production was determined by flow cytometry, and cell viability was determined by MTT assay. Tunicamycin upregulated the mRNA expression of ER stress markers like PERK, ATF4, CHOP, IRE1, XBP1, ATF6 and BiP/GRP78. ER stress induction upregulated the secretion and expression of TNF-α as evidenced by ELISA, PCR and immunoblot analysis. The protein expression of iNOS, COX-2 and total ROS and mitochondrial ROS production were upregulated by tunicamycin in SH-SY5Y cells. Immunoblot analysis suggested that tunicamycin increased the acetylation of NF-κB p65 and downregulates the production of class III histone deacetylase SIRT1 in SH-SY5Y cells. Experiment using resveratrol confirmed the role of SIRT1 in the acetylation of NF-κB p65.

Our results suggest that tunicamycin-induced ER stress upregulated neuronal inflammation through ROS-NF-κB- SIRT1 pathway, and targeting this pathway may provide greater therapeutic potential for managing neuronal inflammation associated with neurodegenerative diseases.