Heat Shock Is Lethal to Fibroblasts Microinjected with Antibodies Against hsp70

TLDR

Heat shock induces synthesis of highly conserved proteins across prokaryotes and eukaryotes, yet direct evidence of their role in mammalian cell survival during stress remains unproven. The study aimed to evaluate the role of hsp70 in heat shock by microinjecting affinity‑purified monoclonal antibodies into fibroblasts. The authors introduced affinity‑purified monoclonal antibodies against hsp70 into fibroblasts via needle microinjection. Antibody‑mediated inhibition of hsp70 prevented its nuclear translocation during mild heat shock and rendered fibroblasts unable to survive a brief 45 °C exposure, whereas control‑antibody‑treated cells survived, demonstrating that functional hsp70 is essential for cell survival under thermal stress.

Abstract

Synthesis of a small group of highly conserved proteins in response to elevated temperature and other agents that induce stress is a universal feature of prokaryotic and eukaryotic cells. Although correlative evidence suggests that these proteins play a role in enhancing survival during and after stress, there is no direct evidence to support this in mammalian cells. To assess the role of the most highly conserved heat shock protein (hsp) family during heat shock, affinity-purified monoclonal antibodies to hsp70 were introduced into fibroblasts by needle microinjection. In addition to impairing the heat-induced translocation of hsp70 proteins into the nucleus after mild heat shock treatment, injected cells were unable to survive a brief incubation at 45°C. Cells injected with control antibodies survived a similar heat shock. These results indicate that functional hsp70 is required for survival of these cells during and after thermal stress.