In Vitro Analysis of Direct Targets of ER Stress Transducer AtbZIP28

The accumulation of unfolded proteins in the lumen of the endoplasmic reticulum (ER) triggers ER stress and activates ER-to-nucleus signaling pathways to alleviate the stress. In Arabidopsis, three bZIP transcription factors (TFs), AtbZIP17, AtbZIP28 and AtbZIP60 are involved in this process, but little is known about gene regulatory network in ER stress response in Arabidopsis. Here, I analyzed the direct targets of ER membrane associated AtbZIP28 identified by DNA affinity purification followed by sequencing (DAP-seq: O’Malley et al., Cell 2016). Unexpectedly, ~5% of direct targets identified by DAP-seq are induced by tunicamycin, suggesting the requirement of other TFs as cofactors for full activation of these target genes and/or the epigenetic regulation.