Reprograming gene expression in hibernatingC. elegansinvolves the IRE-1/XBP-1 pathway

In the wild, many animals respond to cold temperatures by entering hibernation. In the clinic, controlled cooling is used in transplantation and emergency medicine. Yet, the molecular mechanisms that the cells use to survive cold remain largely unexplored. One aspect of cold adaptation is a global downregulation of protein synthesis. Studying it in the nematodeCaenorhabditis elegans, we find that the translation of most mRNAs continues in the cold, albeit at a slower rate, and propose that cold-specific gene expression is regulated primarily at the transcription level. Moreover, we show that the transcription of some cold-induced genes reflects the activation of unfolded protein response (UPR) mediated by the conserved IRE-1/XBP-1 signaling pathway. Our results suggest that the activation of this pathway stems from cold-induced perturbations in proteins and lipids in the endoplasmic reticulum and that its activation is beneficial for cold survival.