Among them, IRE1[alpha]-X-box protein 1 (XBP1
) is the most conserved machinery utilised in the UPR.
XBP-1 is normally kept in its inactive form, but under ERS, the endoRNase domain of IRE-1 splices the mRNA of downstream sensor XBP-1, removing a 26-bp segment from the full-length XBP1
mRNA that generates a translational frameshift, leading to the expression of the active protein XBP-1s.,, XBP-1s binds to intranuclear mRNA directly to regulate protein transcription, thereby affecting subsequent physiological activities., Lee et al .'s study showed for the first time that XBP-1 regulates hepatic lipid metabolism, because XBP1
-knockout mice manifested hypotriglyceridemia and hypocholesterolemia.
is required for the differentiation of plasma cells, dendritic cells, CD[8.sup.+] T cells, and eosinophils, as well as the production of several cytokines in macrophages [9, 10].
Recently, the promoter regions of GPR43 were determined in human monocytes, showing transcription factors including XBP1
were key transcription factors for the regulation of GPR43 expression .
Apart from low expression of proliferation and cell cycle-related genes, luminal A tumors are distinguished by higher expression of PR and FOXA1, GATA3, and XBP1
, whereas the ESR1 gene is expressed at comparable levels as in luminal B tumors , .
Activated IRE1 induces the splicing of XBP1
(X-box-binding protein 1) mRNA by cleaving off its intron .
And their downstream transcription factors include eukaryotic initiation factor 2-[alpha] (eIF2-[alpha]) for PERK, fragmented ATF6 for ATF6, and spliced X-box binding protein 1 (XBP1
) for IRE1.
In model systems, UPR is activated by a set of transcription factors including activating transcription factor 6 (ATF6 (N)), X-box binding protein 1 (XBP1
), and activating transcription factor 4 (ATF4) (Walter and Ron, 2011).
Lugea and colleagues (2011) examined this protective effect in mice with and without the gene for the X-box binding protein 1 (XBP1
), a transcription factor that promotes synthesis of cellular components for protein transport and secretion.
This gene is transcriptionally suppressed by MSX1 and XBP1
Treadmill exercise can improve cardiac function and reduce cardiac infarction by attenuating the expression of GRP78, DERLIN1, p-PERK, p-eIF2a, ATF4/6, XBP1
, CHOP, and cleaved caspase-3 [11, 87].
In the 5% [O.sub.2] group, there was a higher abundance of ATF4, CDX2, DDIT3, KEAP1, HSF1, OTX2, PAF1, POU5F1 (OCT4), REST, SREBF1, and XBP1
factors that are related to several cell cycle processes.