Human HRD1 promoter carries a functional unfolded protein response element to which XBP1 but not ATF6 directly binds.
Quality control of proteins in the endoplasmic reticulum (ER) is achieved by two mechanisms, the productive folding mechanism, which is assisted by a number of ER-localized molecular chaperones and folding enzymes (collectively termed ER chaperones), and the ER-associated degradation (ERAD) mechanism, by which misfolded proteins are degraded by the ubiquitin-dependent proteasome system in the cytosol. Accumulation of unfolded proteins in the ER activates the unfolded protein response (UPR), resulting in transcriptional induction of ER chaperones and ERAD components. In mammals, three signalling pathways operate for the UPR, namely the IRE1-XBP1, PERK-ATF4 and ATF6 pathways. Analysis of mouse embryonic fibroblasts deficient in UPR signalling molecule indicates that transcriptional induction of ERAD components depends on the IRE1-XBP1 pathway. However, the molecular basis of this finding remains unclear. Here, we analysed the promoter of human HRD1, which encodes an E3 ubiquitin ligase, an important component of ERAD. We found that induction of HRD1 is mediated by two cis-acting elements, a canonical ER stress response element and a novel element we designate as UPR element II. The presence of UPR element II to which XBP1 but not ATF6 directly binds explains at least in part the dependency of HRD1 induction on the IRE1-XBP1 pathway.
Yamamoto
Keisuke
K
Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan.
Suzuki
Natsumi
N
Wada
Tadashi
T
Okada
Tetsuya
T
Yoshida
Hiderou
H
Kaufman
Randal J
RJ
Mori
Kazutoshi
K
D051702:Activating Transcription Factor 6 / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004722:Endoribonucleases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D015345:Oligonucleotide Probes / Q000235:genetics; D011401:Promoter Regions, Genetic; D017510:Protein Folding; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000071717:X-Box Binding Protein 1
D051702:Activating Transcription Factor 6; C497112:Atf6 protein, mouse; D004268:DNA-Binding Proteins; D015345:Oligonucleotide Probes; D011994:Recombinant Proteins; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; C000605544:Xbp1 protein, mouse; C482345:SYVN1 protein, human; D044767:Ubiquitin-Protein Ligases; C510185:Ern1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D004722:Endoribonucleases