An alternatively spliced heat shock transcription factor,OsHSFA2dI, functions in the heat stress-induced unfolded protein response in rice

Heat stress regulation of human heat shock genes is mediated by human heat shock transcription factor hHSF1, which contains three 4-3 hydrophobic repeats (LZ1 to LZ3). In unstressed human cells (37 degrees C), hHSF1 appears to be in an inactive, monomeric state that may be maintained through intramolecular interactions stabilized by transient interaction with hsp70. Heat stress (39 to 42 degrees C) disrupts these interactions, and hHSF1 homotrimerizes and acquires heat shock element DNA-binding ability. hHSF1 expressed in Xenopus oocytes also assumes a monomeric, non-DNA-binding state and is converted to a trimeric, DNA-binding form upon exposure of the oocytes to heat shock (35 to 37 degrees C in this organism). Because endogenous HSF DNA-binding activity is low and anti-hHSF1 antibody does not recognize Xenopus HSF, we employed this system for mapping regions in hHSF1 that are required for the maintenance of the monomeric state. The results of mutagenesis analyses strongly suggest that the inactive hHSF1 monomer is stabilized by hydrophobic interactions involving all three leucine zippers which may form a triple-stranded coiled coil. Trimerization may enable the DNA-binding function of hHSF1 by facilitating cooperative binding of monomeric DNA-binding domains to the heat shock element motif. This view is supported by observations that several different LexA DNA-binding domain-hHSF1 chimeras bind to a LexA-binding site in a heat-regulated fashion, that single amino acid replacements disrupting the integrity of hydrophobic repeats render these chimeras constitutively trimeric and DNA binding, and that LexA itself binds stably to DNA only as a dimer but not as a monomer in our assays.

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Inhibition of IRE1α-mediated XBP1 mRNA cleavage by XBP1 reveals a novel regulatory process during the unfolded protein response

Wellcome Open Research ◽

10.12688/wellcomeopenres.11764.1 ◽

2017 ◽

Vol 2 ◽

pp. 36 ◽

Cited By ~ 8

Author(s):

Fiona Chalmers ◽

Bernadette Sweeney ◽

Katharine Cain ◽

Neil J. Bulleid

Keyword(s):

Transcription Factor ◽

Unfolded Protein Response ◽

Target Genes ◽

Feedback Mechanism ◽

Ribonuclease Activity ◽

Stable Cell Line ◽

Factor X ◽

Unfolded Protein ◽

Xbp1 Mrna ◽

Protein Response

Background: The mammalian endoplasmic reticulum (ER) continuously adapts to the cellular secretory load by the activation of an unfolded protein response (UPR). This stress response results in expansion of the ER, upregulation of proteins involved in protein folding and degradation, and attenuation of protein synthesis. The response is orchestrated by three signalling pathways each activated by a specific signal transducer, either inositol requiring enzyme α (IRE1α), double-stranded RNA-activated protein kinase-like ER kinase (PERK) or activating transcription factor 6 (ATF6). Activation of IRE1α results in its oligomerisation, autophosphorylation and stimulation of its ribonuclease activity. The ribonuclease initiates the splicing of an intron from mRNA encoding the transcription factor, X-box binding protein 1 (XBP1), as well as degradation of specific mRNAs and microRNAs. Methods: To investigate the consequence of expression of exogenous XBP1, we generated a stable cell-line expressing spliced XBP1 mRNA under the control of an inducible promotor. Results: Following induction of expression, high levels of XBP1 protein were detected, which allowed upregulation of target genes in the absence of induction of the UPR. Remarkably under stress conditions, the expression of exogenous XBP1 repressed splicing of endogenous XBP1 mRNA without repressing the activation of PERK. Conclusions: These results illustrate that a feedback mechanism exists to attenuate activation of the Ire1α ribonuclease activity in the presence of XBP1.

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A Seed Preferential Heat Shock Transcription Factor from Wheat Provides Abiotic Stress Tolerance and Yield Enhancement in Transgenic Arabidopsis under Heat Stress Environment

PLoS ONE ◽

10.1371/journal.pone.0079577 ◽

2013 ◽

Vol 8 (11) ◽

pp. e79577 ◽

Cited By ~ 33

Author(s):

Harsh Chauhan ◽

Neetika Khurana ◽

Preeti Agarwal ◽

Jitendra P. Khurana ◽

Paramjit Khurana

Keyword(s):

Transcription Factor ◽

Heat Stress ◽

Abiotic Stress ◽

Heat Shock ◽

Stress Tolerance ◽

Transgenic Arabidopsis ◽

Abiotic Stress Tolerance ◽

Heat Shock Transcription Factor ◽

Yield Enhancement ◽

Stress Environment

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Palmitate deranges erythropoietin production via transcription factor ATF4 activation of unfolded protein response

Kidney International ◽

10.1016/j.kint.2018.03.011 ◽

2018 ◽

Vol 94 (3) ◽

pp. 536-550 ◽

Cited By ~ 11

Author(s):

Thitinun Anusornvongchai ◽

Masaomi Nangaku ◽

Tzu-Ming Jao ◽

Chia-Hsien Wu ◽

Yu Ishimoto ◽

...

Keyword(s):

Transcription Factor ◽

Unfolded Protein Response ◽

Unfolded Protein ◽

Erythropoietin Production ◽

Protein Response

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Abstract 3760: Atherogenic Affects Of Arsenic: Role Of Endoplasmic Reticulum Stress And Unfolded Protein Response

Circulation ◽

10.1161/circ.118.suppl_18.s_482 ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Petra Haberzettl ◽

Elena Vladykovskaya ◽

Oleg Barski ◽

Srinivas Sithu ◽

Stanley D’Souza ◽

...

Keyword(s):

Transcription Factor ◽

Unfolded Protein Response ◽

Atherosclerotic Lesion ◽

The United States ◽

Hazardous Substance ◽

Dependent Manner ◽

Lesion Formation ◽

Chemical Chaperone ◽

Unfolded Protein ◽

Protein Response

Arsenic is a global water contaminant and EPA has listed arsenic as a high priority hazardous substance in the United States. Epidemiological studies suggest that chronic arsenic ingestion increases cardiovascular disease in humans, particularly, carotid atherosclerosis. However, mechanisms of arsenic-induced atherogenesis are unknown. We examined the effect of arsenic exposure on early lesion formation in apoE-null mice maintained on water supplemented with (0, 1, 5 and 50 ppm; 3–16 weeks of age) sodium arsenite. Arsenic, did not affect plasma cholesterol but decreased the triglycerides by 18±4 % (P<0.05). NMR analysis of the lipoproteins showed a significant decrease in the abundance of large VLDL particle (>60 nm diameter). Despite a significant decrease in plasma triglyceride, atherosclerotic lesion formation was significantly increased (2– 4 fold; P<0.05 for all doses) in the aortic sinus and the aortic arch of the arsenic-fed mice in a dose dependent manner. Immunohistochemical analysis showed significant increase in the accumulation of macrophages, expression of MCP-1 and unfolded protein response (UPR) dependent activating transcription factor (ATF)-4 and ATF3, in the lesions of arsenic (1ppm) exposed mice. In vitro , arsenic (5–25 μM), significantly increased the expression of ICAM-1, transmigration of differentiated monocytes and expression of the pro-inflammatory cytokine IL-8 in vascular endothelial cells (vEC). Arsenic, also increased the expression of ER-chaperones Grp 78, HERP and calnexin (2– 6 fold; P<0.01). Examination of the effect of arsenic on UPR showed that arsenic, induced the splicing of IRE-1 dependent, bZIP transcription factor XBP-1(alarm phase) and increased the phosphorylation of eIF2α (PERK mediated adaptive phase) by 3 fold (P<0.01) in vEC. Arsenic also induced the expression of the downstream effecter proteins of eIF2α-ATF3 (8 fold; P<0.01) and pro-apoptotic protein CHOP (4 fold; P<0.01) in vEC. Chemical chaperone, phenyl butyric acid (PBA), attenuated the arsenic-induced expression of ATF3 (>90%; P<0.001) and CHOP (>90%; P<0.001). These data suggest that ER-stress and UPR could exacerbate arsenic-induced vascular inflammation and promote atherogenesis.

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Activation of the DNA-binding ability of human heat shock transcription factor 1 may involve the transition from an intramolecular to an intermolecular triple-stranded coiled-coil structure

Molecular and Cellular Biology ◽

10.1128/mcb.14.11.7557-7568.1994 ◽

1994 ◽

Vol 14 (11) ◽

pp. 7557-7568

Author(s):

J Zuo ◽

R Baler ◽

G Dahl ◽

R Voellmy

Keyword(s):

Transcription Factor ◽

Heat Stress ◽

Heat Shock ◽

Dna Binding ◽

Hydrophobic Interactions ◽

Coiled Coil ◽

Heat Shock Transcription Factor ◽

Single Amino Acid ◽

Binding Ability ◽

Heat Shock Element

Heat stress regulation of human heat shock genes is mediated by human heat shock transcription factor hHSF1, which contains three 4-3 hydrophobic repeats (LZ1 to LZ3). In unstressed human cells (37 degrees C), hHSF1 appears to be in an inactive, monomeric state that may be maintained through intramolecular interactions stabilized by transient interaction with hsp70. Heat stress (39 to 42 degrees C) disrupts these interactions, and hHSF1 homotrimerizes and acquires heat shock element DNA-binding ability. hHSF1 expressed in Xenopus oocytes also assumes a monomeric, non-DNA-binding state and is converted to a trimeric, DNA-binding form upon exposure of the oocytes to heat shock (35 to 37 degrees C in this organism). Because endogenous HSF DNA-binding activity is low and anti-hHSF1 antibody does not recognize Xenopus HSF, we employed this system for mapping regions in hHSF1 that are required for the maintenance of the monomeric state. The results of mutagenesis analyses strongly suggest that the inactive hHSF1 monomer is stabilized by hydrophobic interactions involving all three leucine zippers which may form a triple-stranded coiled coil. Trimerization may enable the DNA-binding function of hHSF1 by facilitating cooperative binding of monomeric DNA-binding domains to the heat shock element motif. This view is supported by observations that several different LexA DNA-binding domain-hHSF1 chimeras bind to a LexA-binding site in a heat-regulated fashion, that single amino acid replacements disrupting the integrity of hydrophobic repeats render these chimeras constitutively trimeric and DNA binding, and that LexA itself binds stably to DNA only as a dimer but not as a monomer in our assays.

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Ceapins are a new class of unfolded protein response inhibitors, selectively targeting the ATF6α branch

eLife ◽

10.7554/elife.11878 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 71

Author(s):

Ciara M Gallagher ◽

Carolina Garri ◽

Erica L Cain ◽

Kenny Kean-Hooi Ang ◽

Christopher G Wilson ◽

...

Keyword(s):

Transcription Factor ◽

Er Stress ◽

Unfolded Protein Response ◽

Proteolytic Processing ◽

Unfolded Protein ◽

New Class ◽

Cancer Models ◽

Membrane Bound ◽

The Unfolded Protein Response ◽

Protein Response

The membrane-bound transcription factor ATF6α plays a cytoprotective role in the unfolded protein response (UPR), required for cells to survive ER stress. Activation of ATF6α promotes cell survival in cancer models. We used cell-based screens to discover and develop Ceapins, a class of pyrazole amides, that block ATF6α signaling in response to ER stress. Ceapins sensitize cells to ER stress without impacting viability of unstressed cells. Ceapins are highly specific inhibitors of ATF6α signaling, not affecting signaling through the other branches of the UPR, or proteolytic processing of its close homolog ATF6β or SREBP (a cholesterol-regulated transcription factor), both activated by the same proteases. Ceapins are first-in-class inhibitors that can be used to explore both the mechanism of activation of ATF6α and its role in pathological settings. The discovery of Ceapins now enables pharmacological modulation all three UPR branches either singly or in combination.

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Inhibition of IRE1α-mediated XBP1 mRNA cleavage by XBP1 reveals a novel regulatory process during the unfolded protein response

Wellcome Open Research ◽

10.12688/wellcomeopenres.11764.2 ◽

2017 ◽

Vol 2 ◽

pp. 36 ◽

Cited By ~ 4

Author(s):

Fiona Chalmers ◽

Marcel van Lith ◽

Bernadette Sweeney ◽

Katharine Cain ◽

Neil J. Bulleid

Keyword(s):

Transcription Factor ◽

Unfolded Protein Response ◽

Target Genes ◽

Feedback Mechanism ◽

Ribonuclease Activity ◽

Stable Cell Line ◽

Factor X ◽

Unfolded Protein ◽

Xbp1 Mrna ◽

Protein Response

Background: The mammalian endoplasmic reticulum (ER) continuously adapts to the cellular secretory load by the activation of an unfolded protein response (UPR). This stress response results in expansion of the ER, upregulation of proteins involved in protein folding and degradation, and attenuation of protein synthesis. The response is orchestrated by three signalling pathways each activated by a specific signal transducer, either inositol requiring enzyme α (IRE1α), double-stranded RNA-activated protein kinase-like ER kinase (PERK) or activating transcription factor 6 (ATF6). Activation of IRE1α results in its oligomerisation, autophosphorylation and stimulation of its ribonuclease activity. The ribonuclease initiates the splicing of an intron from mRNA encoding the transcription factor, X-box binding protein 1 (XBP1), as well as degradation of specific mRNAs and microRNAs. Methods: To investigate the consequence of expression of exogenous XBP1, we generated a stable cell-line expressing spliced XBP1 mRNA under the control of an inducible promotor. Results: Following induction of expression, high levels of XBP1 protein were detected, which allowed upregulation of target genes in the absence of induction of the UPR. Remarkably under stress conditions, the expression of exogenous XBP1 repressed splicing of endogenous XBP1 mRNA without repressing the activation of PERK. Conclusions: These results illustrate that a feedback mechanism exists to attenuate Ire1α ribonuclease activity in the presence of XBP1.

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