1. Inhibition of protein translocation at the endoplasmic reticulum promotes activation of the unfolded protein response
- Author
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Stig Linder, Michela Piacenti, Sabine L. Flitsch, Alina Mares, Anna C. Callan, Peristera Roboti, Stephen High, Roger C. Whitehead, Karolina Lesiak-Mieczkowska, Hanna Harant, Marjo Puumalainen, Eileithyia Swanton, Craig McKibbin, and Helen L. Williams
- Subjects
Protein Folding ,XBP1, X-box-binding protein 1 ,non-translocated protein ,EDEM-1, ER degradation-enhancing α-mannosidase-like 1 ,Endoplasmic Reticulum ,Biochemistry ,ERAD, ER-associated degradation ,UPR, unfolded protein response ,Cytosol ,Ubiquitin ,ES, eeyarestatin ,Hydroxyurea ,TCRα, T-cell receptor α subunit ,EndoH, endoglycosidase H ,0303 health sciences ,DMEM, Dulbecco's modified Eagle's medium ,RT, reverse transcription ,biology ,030302 biochemistry & molecular biology ,IP, immunoprecipitation ,unfolded protein response ,PS2, proteasome inhibitor 2 ,eeyarestatin ,Transport protein ,Cell biology ,DNA-Binding Proteins ,Protein Transport ,Protein folding ,PERK, PKR (double-stranded-RNA-dependent protein kinase)-like ER kinase ,Research Article ,UPS, ubiquitin–proteasome system ,Sec61 ,eIF2α, eukaryotic initiation factor 2α ,IRE1, inositol-requiring enzyme 1 ,Endoplasmic-reticulum-associated protein degradation ,Transfection ,ER, endoplasmic reticulum ,HEK, human embryonic kidney ,03 medical and health sciences ,CHX, cycloheximide ,Humans ,cpd A, translocation inhibitor compound A ,PDI, protein disulfide-isomerase ,Molecular Biology ,030304 developmental biology ,Endoplasmic reticulum ,Hydrazones ,Cell Biology ,DTT, dithiothreitol ,Unfolded protein response ,biology.protein ,Peptides ,HeLa Cells - Abstract
Selective small-molecule inhibitors represent powerful tools for the dissection of complex biological processes. ESI (eeyarestatin I) is a novel modulator of ER (endoplasmic reticulum) function. In the present study, we show that in addition to acutely inhibiting ERAD (ER-associated degradation), ESI causes production of mislocalized polypeptides that are ubiquitinated and degraded. Unexpectedly, our results suggest that these non-translocated polypeptides promote activation of the UPR (unfolded protein response), and indeed we can recapitulate UPR activation with an alternative and quite distinct inhibitor of ER translocation. These results suggest that the accumulation of non-translocated proteins in the cytosol may represent a novel mechanism that contributes to UPR activation.
- Published
- 2012
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