scholarly journals The Saccharomycescerevisiae Isw2p-Itc1p Complex RepressesINO1 Expression and Maintains Cell Morphology

2001 ◽  
Vol 183 (17) ◽  
pp. 4985-4993 ◽  
Author(s):  
Minetaka Sugiyama ◽  
Jun-Ichi Nikawa
Keyword(s):  
Leucine Zipper ◽  
Suppressor Gene ◽  
Dominant Negative ◽  
Gene Products ◽  
Truncated Form ◽  
Basic Leucine Zipper ◽  
Multicopy Suppressor ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

ABSTRACT In the yeast Saccharomyces cerevisiae, IRE1 encodes a bifunctional protein with transmembrane kinase and endoribonuclease activities. HAC1 encodes a transcription factor which has a basic leucine zipper domain. Both gene products play a crucial role in the unfolded protein response. Mutants in which one of these genes is defective also show the inositol-auxotrophic (Ino−) phenotype, but the reason for this has not been clear. To investigate the mechanism underlying the Ino−phenotype, we screened a multicopy suppressor gene which can suppress the Ino− phenotype of the Δhac1 strain. We obtained a truncated form of the ITC1 gene that has a defect in its 3′ region. Although the truncated form ofITC1 clearly suppressed the Ino− phenotype of the Δhac1 strain, the full-lengthITC1 had a moderate effect. The gene products ofITC1 and ISW2 are known to constitute a chromatin-remodeling complex (T. Tsukiyama, J. Palmer, C. C. Landel, J. Shiloach, and C. Wu, Genes Dev. 13:686–697, 1999). Surprisingly, the deletion of either ITC1 orISW2 in the Δhac1 strain circumvented the inositol requirement and caused derepression of INO1even under repression conditions, i.e., in inositol-containing medium. These data indicate that the Isw2p-Itc1p complex usually repressesINO1 expression and that overexpression of the truncated form of ITC1 functions in a dominant negative manner inINO1 repression. It is conceivable that the repressor function of this complex is regulated by the C-terminal region of Itc1p.

scholarly journals IRE1β negatively regulates IRE1α signaling in response to endoplasmic reticulum stress

2020 ◽  
Vol 219 (2) ◽  
Author(s):  
Michael J. Grey ◽  
Eva Cloots ◽  
Mariska S. Simpson ◽  
Nicole LeDuc ◽  
Yevgeniy V. Serebrenik ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Kinase Domain ◽  
Dominant Negative ◽  
Hek293 Cells ◽  
Stress Sensor ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

IRE1β is an ER stress sensor uniquely expressed in epithelial cells lining mucosal surfaces. Here, we show that intestinal epithelial cells expressing IRE1β have an attenuated unfolded protein response to ER stress. When modeled in HEK293 cells and with purified protein, IRE1β diminishes expression and inhibits signaling by the closely related stress sensor IRE1α. IRE1β can assemble with and inhibit IRE1α to suppress stress-induced XBP1 splicing, a key mediator of the unfolded protein response. In comparison to IRE1α, IRE1β has relatively weak XBP1 splicing activity, largely explained by a nonconserved amino acid in the kinase domain active site that impairs its phosphorylation and restricts oligomerization. This enables IRE1β to act as a dominant-negative suppressor of IRE1α and affect how barrier epithelial cells manage the response to stress at the host–environment interface.

scholarly journals S-Glutathionylation of Protein Disulfide Isomerase Regulates Estrogen ReceptorαStability and Function

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Ying Xiong ◽  
Yefim Manevich ◽  
Kenneth D. Tew ◽  
Danyelle M. Townsend
Keyword(s):  
Protein Disulfide Isomerase ◽  
Estrogen Receptor Alpha ◽  
Redox Regulation ◽  
Gene Products ◽  
Disulfide Isomerase ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
And Function ◽  
Protein Response ◽  
Protein Disulfide

S-Glutathionylation of cysteine residues within target proteins is a posttranslational modification that alters structure and function. We have shown that S-glutathionylation of protein disulfide isomerase (PDI) disrupts protein folding and leads to the activation of the unfolded protein response (UPR). PDI is a molecular chaperone for estrogen receptor alpha(ERα). Our present data show in breast cancer cells that S-glutathionylation of PDI interferes with its chaperone activity and abolishes its capacity to form a complex withERα. Such drug treatment also reverses estradiol-induced upregulation of c-Myc, cyclinD1, andP21Cip, gene products involved in cell proliferation. Expression of an S-glutathionylation refractory PDI mutant diminishes the toxic effects of PABA/NO. Thus, redox regulation of PDI causes its S-glutathionylation, thereby mediating cell death through activation of the UPR and abrogation ofERαstability and signaling.

scholarly journals Misfolding, altered membrane distributions, and the unfolded protein response contribute to pathogenicity differences in Na,K-ATPase ATP1A3 mutations

2020 ◽  
pp. jbc.RA120.015271
Author(s):  
Elena Arystarkhova ◽  
Laurie J Ozelius ◽  
Allison Brashear ◽  
Kathleen J Sweadner
Keyword(s):  
Unfolded Protein Response ◽  
Age Of Onset ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Atpase Subunit ◽  
Α Subunit ◽  
Unfolded Protein ◽  
Er Retention ◽  
The Unfolded Protein Response ◽  
Protein Response

Missense mutations in ATP1A3, the α3 isoform of Na,K-ATPase, cause neurological phenotypes that differ greatly in symptoms and severity.  A mechanistic basis for differences is lacking, but reduction of activity alone cannot explain them.  Isogenic cell lines with endogenous α1 and inducible exogenous α3 were constructed to compare mutation properties.  Na,K-ATPase is made in endoplasmic reticulum, but glycan-free catalytic α subunit complexes with glycosylated β subunit in the ER to proceed through Golgi and post-Golgi trafficking.  We previously observed classic evidence of protein misfolding in mutations with severe phenotypes:  differences in ER retention of endogenous β1 subunit, impaired trafficking of α3, and cytopathology, suggesting that they misfold during biosynthesis.  Here we tested two mutations associated with different phenotypes:  D923N, which has a median age of onset of hypotonia or dystonia at 3 years, and L924P, with severe infantile epilepsy and profound impairment.  Misfolding during biosynthesis in the ER activates the unfolded protein response (UPR), a multi-armed program that enhances protein folding capacity, and if that fails, triggers apoptosis.  L924P showed more nascent protein retention in ER than D923N; more ER-associated degradation of α3 (ERAD); larger differences in Na,K-ATPase subunit distributions among subcellular fractions; and greater inactivation of eIF2α, a major defensive step of the UPR.  In L924P there was also altered subcellular distribution of endogenous α1 subunit, analogous to a dominant negative effect.  Both mutations showed pro-apoptotic sensitization by reduced phosphorylation of BAD.  Encouragingly, however, 4-phenylbutyrate (4PBA), a pharmacological corrector, reduced L924P ER retention, increased α3 expression, and restored morphology.

The Anti-Apoptotic Role of the Unfolded Protein Response in Bcr-Abl Positive Leukemia Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4527-4527
Author(s):  
Atsuko Tanimura ◽  
Toshiaki Yujiri ◽  
Yoshinori Tanaka ◽  
Yukio Tanizawa
Keyword(s):  
Unfolded Protein Response ◽  
Dominant Negative ◽  
Leukemic Cells ◽  
Luciferase Assay ◽  
Leukemia Cells ◽  
Unfolded Protein ◽  
Ph Chromosome ◽  
The Unfolded Protein Response ◽  
Protein Response

Abstract Accumulation of unfolded or misfolded proteins within the endoplasmic reticulum triggers the unfolded protein response (UPR). Evidence from several studies suggests that the UPR is activated in various tumors and might play a crucial role in tumor growth. However, the role of the UPR in leukemia remains unclear. Therefore, to define the role of the UPR in leukemogenesis, we used p210 Bcr-Abl-expressing 32D myeloid cell lines (p210 32D). The mRNA expression of UPR-related genes, namely, a spliced form of X-box DNA-binding protein (XBP1) and glucose regulated protein 78 (GRP78), was increased in p210 32D. Luciferase assay indicated that p210 Bcr-Abl induced high levels of the transcriptional activity of the UPR element. Moreover, levels of the phosphorylated eIF2 alpha protein increased in p210 32D. Inhibition of the UPR using IRE1 and ATF6 dominant-negative mutants diminished the ability of Bcr-Abl to protect the cells from etoposide- and imatinib-induced apoptosis, but had no effect on the proliferation of p210 Bcr-Abl-transformed cells. We also evaluated the expression of UPR-related genes in primary leukemic cells from Ph chromosome-positive cells by real-time RT-PCR; it was found that these cells showed higher expression levels than the control cells. Taken together, these results for the first time suggested that UPR is a downstream target of the Bcr-Abl oncoprotein, and it plays the anti-apoptotic role of Bcr-Abl in Ph chromosome-positive leukemia cells.

scholarly journals SCFCdc4-mediated Degradation of the Hac1p Transcription Factor Regulates the Unfolded Protein Response inSaccharomyces cerevisiae

2007 ◽  
Vol 18 (2) ◽  
pp. 426-440 ◽  
Author(s):  
Bhupinder Pal ◽  
Nickie C. Chan ◽  
Leon Helfenbaum ◽  
Kaeling Tan ◽  
William P. Tansey ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Unfolded Protein Response ◽  
Rna Polymerase Ii ◽  
Nuclear Localization ◽  
Leucine Zipper ◽  
Nuclear Localization Sequence ◽  
Basic Leucine Zipper ◽  
Unfolded Protein ◽  
Yeast Genes ◽  
Protein Response

The Saccharomyces cerevisiae basic leucine zipper transcription factor Hac1p is synthesized in response to the accumulation of unfolded polypeptides in the lumen of the endoplasmic reticulum (ER), and it is responsible for up-regulation of ∼5% of all yeast genes, including ER-resident chaperones and protein-folding catalysts. Hac1p is one of the most short-lived yeast proteins, having a half-life of ∼1.5 min. Here, we have shown that Hac1p harbors a functional PEST degron and that degradation of Hac1p by the proteasome involves the E2 ubiquitin-conjugating enzyme Ubc3/Cdc34p and the SCFCdc4E3 complex. Consistent with the known nuclear localization of Cdc4p, rapid degradation of Hac1p requires the presence of a functional nuclear localization sequence, which we demonstrated to involve basic residues in the sequence29RKRAKTK35. Two-hybrid analysis demonstrated that the PEST-dependent interaction of Hac1p with Cdc4p requires Ser146 and Ser149. Turnover of Hac1p may be dependent on transcription because it is inhibited in cell mutants lacking Srb10 kinase, a component of the SRB/mediator module of the RNA polymerase II holoenzyme. Stabilization of Hac1p by point mutation or deletion, or as the consequence of defects in components of the degradation pathway, results in increased unfolded protein response element-dependent transcription and improved cell viability under ER stress conditions.

Oestrogen-driven changes in the bovine uterus are associated with activation of the unfolded protein response

2014 ◽  
Author(s):  
Mohammed A Alfattah ◽  
Paul Anthony McGettigan ◽  
John Arthur Browne ◽  
Khalid M Alkhodair ◽  
Katarzyna Pluta ◽  
...  
Keyword(s):  
Unfolded Protein Response ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Native Ubiquitin Structural Changes Resulting from Complexation with β-methylamino-L-alanine (BMAA)

2020 ◽  
Author(s):  
Katie Mae Wilson ◽  
Aurora Burkus-Matesevac ◽  
Samuel Maddox ◽  
Christopher Chouinard
Keyword(s):  
Structural Changes ◽  
Noncovalent Complex ◽  
Unfolded Protein ◽  
Protein Size ◽  
High Concentrations ◽  
The Unfolded Protein Response ◽  
Critical Binding ◽  
Protein Response ◽  
The Brain ◽  
Lateral Sclerosis

β-methylamino-L-alanine (BMAA) has been linked to the development of neurodegenerative (ND) symptoms following chronic environmental exposure through water and dietary sources. The brains of those affected by this condition, often referred to as amyotrophic lateral sclerosis-parkinsonism-dementia complex (ALS-PDC), have exhibited the presence of plaques and neurofibrillary tangles (NFTs) from protein aggregation. Although numerous studies have sought to better understand the correlation between BMAA exposure and onset of ND symptoms, no definitive link has been identified. One prevailing hypothesis is that BMAA acts a small molecule ligand, complexing with critical proteins in the brain and reducing their function. The objective of this research was to investigate the effects of BMAA exposure on the native structure of ubiquitin. We hypothesized that formation of a Ubiquitin+BMAA noncovalent complex would alter the protein’s structure and folding and ultimately affect the ubiquitinproteasome system (UPS) and the unfolded protein response (UPR). Ion mobility-mass spectrometry revealed that at sufficiently high concentrations BMAA did in fact form a noncovalent complex with ubiquitin, however similar complexes were identified for a range of additional amino acids. Collision induced unfolding (CIU) was used to interrogate the unfolding dynamics of native ubiquitin and these Ubq-amino acid complexes and it was determined that complexation with BMAA led to a significant alteration in native protein size and conformation, and this complex required considerably more energy to unfold. This indicates that the complex remains more stable under native conditions and this may indicate that BMAA has attached to a critical binding location.

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