Dynamics of heat shock response during neural differentiation and culture of mouse embryonic stem cell-derived neural stem cells.

The central nervous system (CNS) is highly vulnerable to heat exposure during development, yet how heat shock (HS) responses vary across defined stages of neural differentiation remains unclear. Using a mouse embryonic stem cell‑derived neural stem cell (NSC) model, we examined stage‑dependent responses to acute HS. Cells were exposed at Day 0, Day 2, or Day 6 to 43-44°C for 20  min, followed by assessment of viability, apoptosis, Hsp gene expression, and lineage marker expression. HS at Day 0 caused marked reductions in viability together with increased caspase‑3/7 activity, whereas cells at later stages showed progressive recovery of viability and no detectable increase in caspase activity, accompanied by stronger induction of Hsp70 and Hsp90. At Day 6, HS had little effect on neuronal MAP2 expression, while GFAP mRNA levels were significantly reduced, indicating a transient suppression of astrocytic differentiation under HS conditions. These findings demonstrate stage‑dependent changes in HS responsiveness during neural differentiation, characterized by restored survival and reduced cell‑death susceptibility at later stages, together with a temporary attenuation of astrocytic differentiation.