Assessment of eIF2α phosphorylation during immunogenic cell death

Immunogenic cell death (ICD) is a modality of cellular demise that when it is induced by certain anticancer treatments can ignite an adaptive anticancer immune response. ICD is characterized by the emission of a specific set of danger-associated molecular patterns (DAMPs) including calreticulin exposure at the plasma membrane, ATP liberation, HMGB1 exodus and type-I IFN release. The apical signaling triggering the appearance of these hallmarks involves the phosphorylation on serine 51 of the α-subunit of eukaryotic initiation factor 2 (EIF2), a key protein in the orchestration of endoplasmic reticulum (ER) stress responses. EIF2α can be phosphorylated by a family of four EIF2A kinases: EIF2AK1–4 (best known as heme regulated inhibitor, HRI, protein kinase R, PKR, protein kinase R-like endoplasmic reticulum kinase, PERK, and general control non-derepressible 2, GCN2), that each respond to a specific type of cellular stress. Here, we describe different techniques to investigate the biochemical pathways leading to eIF2α phosphorylation in the context of ICD.