scholarly journals Pharmacological Targeting of the ER-Resident Chaperones GRP94 or Cyclophilin B Induces Secretion of IL-22 Binding Protein Isoform-1 (IL-22BPi1)

2019 ◽  
Vol 20 (10) ◽  
pp. 2440
Author(s):  
Paloma Gómez-Fernández ◽  
Andoni Urtasun ◽  
Ianire Astobiza ◽  
Jorge Mena ◽  
Iraide Alloza ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Binding Protein ◽  
Secreted Protein ◽  
Complex Type ◽  
Cyclophilin B ◽  
Interleukin 22 ◽  
Unfolded Protein ◽  
Protein Isoform ◽  
High Mannose ◽  
Protein Response

Of the three interleukin-22 binding protein (IL-22BP) isoforms produced by the human IL22RA2 gene, IL-22BPi2 and IL-22BPi3 are capable of neutralizing IL-22. The longest isoform, IL-22BPi1, does not bind IL-22, is poorly secreted, and its retention within the endoplasmic reticulum (ER) is associated with induction of an unfolded protein response (UPR). Therapeutic modulation of IL-22BPi2 and IL-22BPi3 production may be beneficial in IL-22-dependent disorders. Recently, we identified the ER chaperones GRP94 and cyclophilin B in the interactomes of both IL-22BPi1 and IL-22BPi2. In this study, we investigated whether secretion of the IL-22BP isoforms could be modulated by pharmacological targeting of GRP94 and cyclophilin B, either by means of geldanamycin, that binds to the ADP/ATP pocket shared by HSP90 paralogs, or by cyclosporin A, which causes depletion of ER cyclophilin B levels through secretion. We found that geldanamycin and its analogs did not influence secretion of IL-22BPi2 or IL-22BPi3, but significantly enhanced intracellular and secreted levels of IL-22BPi1. The secreted protein was heterogeneously glycosylated, with both high-mannose and complex-type glycoforms present. In addition, cyclosporine A augmented the secretion of IL-22BPi1 and reduced that of IL-22BPi2 and IL-22BPi3. Our data indicate that the ATPase activity of GRP94 and cyclophilin B are instrumental in ER sequestration and degradation of IL-22BPi1, and that blocking these factors mobilizes IL-22BPi1 toward the secretory route.

scholarly journals Long Interleukin-22 Binding Protein Isoform-1 Is an Intracellular Activator of the Unfolded Protein Response

2018 ◽  
Vol 9 ◽  
Author(s):  
Paloma Gómez-Fernández ◽  
Andoni Urtasun ◽  
Adrienne W. Paton ◽  
James C. Paton ◽  
Francisco Borrego ◽  
...  
Keyword(s):  
Unfolded Protein Response ◽  
Binding Protein ◽  
Interleukin 22 ◽  
Unfolded Protein ◽  
Protein Isoform ◽  
The Unfolded Protein Response ◽  
Protein Response

scholarly journals Induction of the FK506-binding protein, FKBP13, under conditions which misfold proteins in the endoplasmic reticulum

1994 ◽  
Vol 303 (3) ◽  
pp. 705-708 ◽  
Author(s):  
K T Bush ◽  
B A Hendrickson ◽  
S K Nigam
Keyword(s):  
Endoplasmic Reticulum ◽  
Mdck Cells ◽  
Binding Protein ◽  
Significant Similarity ◽  
Fk506 Binding Protein ◽  
Unfolded Protein ◽  
Immunoglobulin Binding Protein ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Immunoglobulin Binding

In order to determine whether the endoplasmic reticulum (ER) luminal FK506-binding protein, FKBP13, shares properties of ER molecular chaperones, MDCK cells were treated with either tunicamycin or Ca2+ ionophores. By Northern-blot analysis, tunicamycin resulted in a 2-fold rise in FKBP13 mRNA, whereas ionophores (A23187 and ionomycin) caused a more impressive rise in FKBP13 mRNA (up to 5-fold with ionomycin). Actinomycin D chase experiments in ionomycin-treated cells revealed no change in the half-life of FKBP13 mRNA, indicating that the increase in FKBP13 mRNA observed was not due to greater message stability. Moreover, sequencing of the 5′ flanking region of the gene for murine FKBP13 revealed significant similarity to similar regions in human BiP (immunoglobulin-binding protein) and the human glucose-regulated protein grp94, including a 37 bp sequence in FKBP13 with approximately 50% identity with the unfolded protein response element of the BiP gene. Together, these data suggest a role for FKBP13 in ER protein folding.

scholarly journals Quercetin Affects Hsp70/IRE1αMediated Protection from Death Induced by Endoplasmic Reticulum Stress

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Antonello Storniolo ◽  
Marisa Raciti ◽  
Alessandra Cucina ◽  
Mariano Bizzarri ◽  
Livia Di Renzo
Keyword(s):  
Endoplasmic Reticulum ◽  
Binding Protein ◽  
Human Leukemia ◽  
Unfolded Protein ◽  
Homologous Protein ◽  
Dietary Flavonoid ◽  
Induced Apoptosis ◽  
The Unfolded Protein Response ◽  
Shock Proteins ◽  
Protein Response

Relative to their normal counterparts, tumor cells generally exhibit a greater “stress phenotype” and express heat shock proteins (Hsp) that represent candidate targets for anticancer therapy. Here we investigated the role of Hsp70 in survival induced by endoplasmic reticulum (ER) stressors in human leukemia U937 cells. Quercetin, a major dietary flavonoid, or specific silencing affected the expression level of Hsp70 and did not allow the upregulation of inositol-requiring kinase 1α(IRE1α), the prototype ER stress sensor regulating the unfolded protein response (UPR), that protects the cells against the stress of misfolded proteins in the ER. The reduction of Hsp70 prevented the upregulation of immunoglobulin heavy-chain binding protein (BiP), but not of CCAAT/enhancer-binding protein-homologous protein (CHOP), and induced apoptosis. Also specific silencing of IRE1αor inhibition of its endoribonuclease activity by 4μ8c hampered the upregulation of BiP, but not of CHOP, and induced apoptosis. These results suggest that drugs affecting the Hsp70-IRE1αaxis, like quercetin, or affecting directly IRE1αmay represent an effective adjuvant antileukemia therapy.

scholarly journals Unfolded protein response is involved in the pathology of human congenital hypothyroid goiter and rat non-goitrous congenital hypothyroidism

2004 ◽  
Vol 32 (3) ◽  
pp. 903-920 ◽  
Author(s):  
M Baryshev ◽  
E Sargsyan ◽  
G Wallin ◽  
A Lejnieks ◽  
S Furudate ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Unfolded Protein Response ◽  
Congenital Hypothyroidism ◽  
Intracellular Signaling ◽  
Binding Protein ◽  
Active Form ◽  
Rat Tissues ◽  
Unfolded Protein ◽  
Er Chaperone ◽  
Protein Response

The unfolded protein response (UPR) is an intracellular signaling pathway that regulates the protein folding and processing capacity of the endoplasmic reticulum (ER). The UPR is induced by the pharmacological agents that perturb ER functions but is also activated upon excessive accumulation of the mutant secretory proteins that are unable to attain correct three-dimensional structure and are thus retained in the ER. Such defects in intracellular protein transport underlie the development of a number of phenotypically diverse inherited pathologies, termed endoplasmic reticulum storage diseases (ERSD). We have studied UPR development in two similar ERSDs, human congenital goiter caused by the C1264R and C1996S mutations in the thyroglobulin (Tg) gene and non-goitrous congenital hypothyroidism in rdw dwarf rats determined by the G2320R Tg mutation. In both cases, these mutations rendered Tg incapable of leaving the ER. A major ER chaperone immunoglobulin-binding protein (BiP), and a novel putative escort chaperone endoplasmic reticulum protein 29 KDa (ERp29) were found to be associated with Tg, which might be interpreted as the contribution of the quality control machinery to the previously shown retention of Tg in the ER. We have extended our earlier observations of ER chaperone induction with the identification of the additional ER (ERp29, ERp72, calreticulin, protein disulfide isomerase (PDI)), cytoplasmic (heat shock protein (HSP)70, HSP90) and mitochondrial (mtHSP70) upregulated chaperones and folding enzymes. Activation of the transcriptional arm of UPR, as judged by the appearance of the spliced (active) form of X-box binding protein (XBP1) and processed activating transcription factor 6 (ATF6) transcription factors was suggested to contribute to the overexpression of the ER chaperones. The processing of ATF6 was observed in both human and rat tissues with Tg mutations. Whereas, in human tissues, weak splicing of XBP1 mRNA was detected only in the C1264R mutant, all rat thyroids including wild-type contained significant amounts of the spliced form of XBP1 as opposed to human liver and rat brain tissues, implying the existence of a previously unknown tissue-specific regulation of XBP1 processing.

scholarly journals Enhanced Biosynthesis of Coagulation Factor VIII through Diminished Engagement of the Unfolded Protein Response

2011 ◽  
Vol 286 (27) ◽  
pp. 24451-24457 ◽  
Author(s):  
Harrison C. Brown ◽  
Bagirath Gangadharan ◽  
Christopher B. Doering
Keyword(s):  
Endoplasmic Reticulum ◽  
Factor Viii ◽  
Unfolded Protein Response ◽  
Binding Protein ◽  
Coagulation Factor ◽  
Coagulation Factor Viii ◽  
Luciferase Reporter ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Human and porcine coagulation factor VIII (fVIII) display a biosynthetic efficiency differential that is being exploited for the development of new protein and gene transfer-based therapies for hemophilia A. The cellular and/or molecular mechanism(s) responsible for this phenomenon have yet to be uncovered, although it has been temporally localized to post-translational biosynthetic steps. The unfolded protein response (UPR) is a cellular adaptation to structurally distinct (e.g. misfolded) or excess protein in the endoplasmic reticulum and is known to be induced by heterologous expression of recombinant human fVIII. Therefore, it is plausible that the biosynthetic differential between human and porcine fVIII results from differential UPR activation. In the current study, UPR induction was examined in the context of ongoing fVIII expression. UPR activation was greater during human fVIII expression when compared with porcine fVIII expression as determined by ER response element (ERSE)-luciferase reporter activity, X-box-binding protein 1 (XBP1) splicing, and immunoglobulin-binding protein (BiP) up-regulation. Immunofluorescence microscopy of fVIII expressing cells revealed that human fVIII was notably absent in the Golgi apparatus, confirming that endoplasmic reticulum to Golgi transport is rate-limiting. In contrast, a significant proportion of porcine fVIII was localized to the Golgi indicating efficient transit through the secretory pathway. Overexpression of BiP, an integral UPR protein, reduced the secretion of human fVIII by 50%, but had no effect on porcine fVIII biosynthesis. In contrast, expression of BiP shRNA increased human fVIII expression levels. The current data support the model of differential engagement of UPR by human and porcine fVIII as a non-traditional mechanism for regulation of gene product biosynthesis.

scholarly journals Pumilio protects Xbp1 mRNA from regulated Ire1-dependent decay

2021 ◽  
Author(s):  
Fatima Cairrao ◽  
Cristiana C Santos ◽  
Adrien Le Thomas ◽  
Scot Marsters ◽  
Avi Ashkenazi ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Binding Sites ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Unfolded Protein ◽  
Xbp1 Mrna ◽  
Regulatory Link ◽  
The Unfolded Protein Response ◽  
Protein Response

SUMMARYThe unfolded protein response (UPR) maintains homeostasis of the endoplasmic reticulum(ER). Residing in the ER membrane, the UPR mediator Ire1 deploys its cytoplasmic kinase-endoribonuclease domain to activate the key UPR transcription factor Xbp1 through non-conventional splicing of Xbp1 mRNA. Ire1 also degrades diverse ER-targeted mRNAs through regulated Ire1-dependent decay (RIDD), but how it spares Xbp1 mRNA from this decay is unknown. We identified binding sites for the RNA-binding protein Pumilio in the 3’UTR Drosophila Xbp1. In the developing Drosophila eye, Pumilio bound both the Xbp1unspliced and Xbp1spliced mRNAs, but only Xbp1spliced was stabilized by Pumilio. Furthermore, Pumilio displayed Ire1 kinase-dependent phosphorylation during ER stress, which was required for its stabilization of Xbp1spliced. Human IRE1 could directly phosphorylate Pumilio, and phosphorylated Pumilio protected Xbp1spliced mRNA against RIDD. Thus, Ire1-mediated phosphorylation enables Pumilio to shield Xbp1spliced from RIDD. These results uncover an important and unexpected regulatory link between an RNA-binding protein and the UPR.

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