IRE1 and XBP-1 effects on the Drosophila unfolded protein response

The unfolded protein response (UPR) allows the endoplasmic reticulum (ER) to recover from the accumulation of misfolded proteins, in part by increasing its folding capacity. IRE1 promotes this remodeling by detecting misfolded ER proteins and activating a transcription factor, XBP-1, through endonucleolytic cleavage of its mRNA. We found that IRE1 independently mediated the rapid degradation of a specific subset of mRNAs. The arrays deposited here show the effects of depletion of IRE1 and XBP-1 on UPR induction in S2 cells. We have characterized the IRE1-dependent repressive branch of this response. Keywords: stress response, RNAi, DTT We knocked down IRE1, XBP-1, or neither (control) in S2 cells using RNAi, and then induced the UPR with DTT, a reducing agent that disrupts disulphide-linked folding. Each experiment was done in triplicate. Each sample (varying RNAi and -/+ DTT) was hybridized to a single spotted array along with a reference sample, which was the same for all arrays.