Transcriptomics Unveil Canonical and Non-Canonical Heat Shock-Induced Pathways in Human Cell Lines

The cellular stress response (CSR) is a conserved mechanism that protects cells from environmental and physiological stressors. The heat shock response (HSR), a critical component of the CSR, utilizes molecular chaperones to mitigate proteotoxic stress caused by elevated temperatures. We hypothesized that while the canonical HSR pathways are conserved across cell types, specific cell lines may exhibit unique transcriptional responses to heat shock. To test this, we compared the transcriptomic responses of HEK293, HepG2, and HeLa cells under control conditions immediately following heat shock and after an 8-hour recovery period. RNA sequencing revealed conserved activation of canonical HSR pathways, including the unfolded protein response, alongside enrichment of the non-canonical "Receptor Ligand Activity" pathway across all cell lines. Cell line-specific variations were also observed, with HepG2 cells displaying more uniquely expressed genes and elevated expression levels (fold changes) of shared genes under stress conditions. Validation by qPCR confirmed the activation of key genes within the "Receptor Ligand Activity" pathway across time points. These findings provide insights into conserved and context-specific aspects of the HSR, contributing to a more comprehensive understanding of stress response mechanisms across mammalian cells.