Transcription Factor ATF4 Induces NLRP1 Inflammasome Expression during Endoplasmic Reticulum Stress.

Perturbation of endoplasmic reticulum (ER) homeostasis triggers the ER stress response (also known as Unfolded Protein Response), a hallmark of many pathological disorders. However the connection between ER stress and inflammation remains largely unexplored. Recent data suggest that ER stress controls the activity of inflammasomes, key signaling platforms that mediate innate immune responses. Here we report that expression of NLRP1, a core inflammasome component, is specifically up-regulated during severe ER stress conditions in human cell lines. Both IRE1α and PERK, but not the ATF6 pathway, modulate NLRP1 gene expression. Furthermore, using mutagenesis, chromatin immunoprecipitation and CRISPR-Cas9-mediated genome editing technology, we demonstrate that ATF4 transcription factor directly binds to NLRP1 promoter during ER stress. Although involved in different types of inflammatory responses, XBP-1 splicing was not required for NLRP1 induction. This study provides further evidence that links ER stress with innate