Genomic insights into the tunicamycin-induced endoplasmic reticulum stress response in peripheral blood mononuclear cells: A comprehensive RNA sequencing analysis

Tunicamycin induces endoplasmic reticulum (ER) stress by inhibiting N-glycosylation of newly synthesized proteins, leading to accumulation of misfolded proteins in the ER. This activates the unfolded protein response (UPR), a conserved adaptive pathway aimed at restoring proteostasis. A key mediator of this response is the kinase PERK which activates a signal cascade that leads to a global reduction in translation, while selectively enhancing the expression of stress-associated genes. This PERK-mediated response also constitutes a major arm of the integrated stress response (ISR). Under persistent ER stress, these response pathways may trigger pro-apoptotic programs in addition to adaptive responses. In this study, we used next-generation RNA sequencing to profile transcriptional changes in peripheral blood mononuclear cells (PBMCs) after 24 h of tunicamycin exposure, alone or with the PERK inhibitor GSK2606414 or the eIF2B activator ISRIB, to assess stress responses at distinct regulatory points within the PERK-ISR pathway. Key findings were validated by qRT-PCR, and pathway enrichment analysis was performed using the Gene Ontology Resource and the Reactome database. ER stress altered gene expression, with 4.80% of genes upregulated and 12.67% downregulated. GSK2606414 suppressed a broader subset of tunicamycin-induced genes than ISRIB. However, both inhibitors effectively reversed upregulation of the top two stress-responsive genes, TNC and WNT5A. Pathway enrichment analysis revealed overrepresentation of pathways related to ER stress responses, unfolded protein homeostasis, ER chaperone complex assembly, amino acid biosynthesis and interconversion, and aminoacyl-tRNA synthetase-mediated protein translation. These findings provide mechanistic insights into chronic ER stress in PBMCs and identify WNT5A and TNC as candidate biomarkers, pending further validation.