scholarly journals ADP-ribose Transferase PARP16 Mediated-unfolded Protein Response Contributes to Neuronal Cell Damage in Cerebral Ischemia/Reperfusion

2021 ◽  
Author(s):  
Jinghuan Wang ◽  
zhenghua Su ◽  
wen Zhong ◽  
haibi Su ◽  
Jie Xu ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Cortical Neurons ◽  
Cell Damage ◽  
Transmembrane Protein ◽  
Ischemia Reperfusion ◽  
Neuronal Cell ◽  
Unfolded Protein ◽  
Protein Response

Abstract Ischemic stroke is known to cause the accumulation of misfolded proteins and loss of calcium homeostasis leading to impairment of endoplasmic reticulum (ER) function and activating the unfolded protein response (UPR). PARP16 is the only an active ADP-ribosyl transferase known tail-anchored ER transmembrane protein with a cytosolic catalytic domain. Here, we find PARP16 is highly expressed in ischemic cerebral hemisphere and Oxygen-glucose deprivation (OGD)-treated immortalized hippocampal neuroblasts HT22 cells. Using adeno-associated virus-mediated knockdown PARP16 mice, we find knockdown PARP16 decreases infarct demarcations and has a better neurological outcome after ischemic stroke. Our data indicate PARP16 overexpression promotes ER stress-mediated cell damage in primary cortical neurons, in turn, knockdown PARP16 decreases ER stress and neuronal death caused by OGD. Furthermore, PARP16 functions mechanistically as ADP-ribosyltransferase to modulate the level of ribosylation of the corresponding PERK and IRE1α arm of the UPR, and that such modification is required for activation of PERK and IRE1α. Indeed, pharmacological stimulation of the UPR using Brefeldin A counteracts knockdown of PARP16-mediated neuronal protection in OGD. On other hand, when an ER inhibitor Tauroursodeoxycholic acid present, permit more obvious protection and inactivation of PERK and IRF1α caused by knockdown of PARP16. In conclusion, PARP16 plays a crucial role in post-ischemic UPR and the knockdown of PARP16 alleviates brain injury after ischemic stroke. The rationale of this study is to explore the potentials of the PARP16-PERK/IRE1α axis as a target for neuronal survival in ischemic stroke.

scholarly journals ATF6 Activated by Proteolysis Binds in the Presence of NF-Y (CBF) Directly to the cis-Acting Element Responsible for the Mammalian Unfolded Protein Response

2000 ◽  
Vol 20 (18) ◽  
pp. 6755-6767 ◽  
Author(s):  
Hiderou Yoshida ◽  
Tetsuya Okada ◽  
Kyosuke Haze ◽  
Hideki Yanagi ◽  
Takashi Yura ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Intracellular Signaling ◽  
Transmembrane Protein ◽  
Consensus Sequence ◽  
Soluble Form ◽  
Dominant Negative Mutant ◽  
Unfolded Protein ◽  
Protein Response

ABSTRACT Transcription of genes encoding molecular chaperones and folding enzymes in the endoplasmic reticulum (ER) is induced by accumulation of unfolded proteins in the ER. This intracellular signaling, known as the unfolded protein response (UPR), is mediated by thecis-acting ER stress response element (ERSE) in mammals. In addition to ER chaperones, the mammalian transcription factor CHOP (also called GADD153) is induced by ER stress. We report here that the transcription factor XBP-1 (also called TREB5) is also induced by ER stress and that induction of CHOP and XBP-1 is mediated by ERSE. The ERSE consensus sequence is CCAAT-N9-CCACG. As the general transcription factor NF-Y (also known as CBF) binds to CCAAT, CCACG is considered to provide specificity in the mammalian UPR. We recently found that the basic leucine zipper protein ATF6 isolated as a CCACG-binding protein is synthesized as a transmembrane protein in the ER, and ER stress-induced proteolysis produces a soluble form of ATF6 that translocates into the nucleus. We report here that overexpression of soluble ATF6 activates transcription of the CHOP and XBP-1 genes as well as of ER chaperone genes constitutively, whereas overexpression of a dominant negative mutant of ATF6 blocks the induction by ER stress. Furthermore, we demonstrated that soluble ATF6 binds directly to CCACG only when CCAAT exactly 9 bp upstream of CCACG is bound to NF-Y. Based on these and other findings, we concluded that specific and direct interactions between ATF6 and ERSE are critical for transcriptional induction not only of ER chaperones but also of CHOP and XBP-1.

scholarly journals Sigma-1 Receptor Is Critical for Mitochondrial Activity and Unfolded Protein Response in Larval Zebrafish

2021 ◽  
Vol 22 (20) ◽  
pp. 11049
Author(s):  
Lucie Crouzier ◽  
Morgane Denus ◽  
Elodie M. Richard ◽  
Amarande Tavernier ◽  
Camille Diez ◽  
...  
Keyword(s):  
Er Stress ◽  
Unfolded Protein Response ◽  
Transmembrane Protein ◽  
Critical Role ◽  
Mitochondrial Activity ◽  
Sigma 1 Receptor ◽  
Unfolded Protein ◽  
Sigma 1 ◽  
Protein Response ◽  
The Impact

The sigma-1 receptor (S1R) is a highly conserved transmembrane protein highly enriched in mitochondria-associated endoplasmic reticulum (ER) membranes, where it interacts with several partners involved in ER-mitochondria Ca2+ transfer, activation of the ER stress pathways, and mitochondria function. We characterized a new S1R deficient zebrafish line and analyzed the impact of S1R deficiency on visual, auditory and locomotor functions. The s1r+25/+25 mutant line showed impairments in visual and locomotor functions compared to s1rWT. The locomotion of the s1r+25/+25 larvae, at 5 days post fertilization, was increased in the light and dark phases of the visual motor response. No deficit was observed in acoustic startle response. A critical role of S1R was shown in ER stress pathways and mitochondrial activity. Using qPCR to analyze the unfolded protein response genes, we observed that loss of S1R led to decreased levels of IRE1 and PERK-related effectors and increased over-expression of most of the effectors after a tunicamycin challenge. Finally, S1R deficiency led to alterations in mitochondria bioenergetics with decreased in basal, ATP-linked and non-mitochondrial respiration and following tunicamycin challenge. In conclusion, this new zebrafish model confirmed the importance of S1R activity on ER-mitochondria communication. It will be a useful tool to further analyze the physiopathological roles of S1R.

scholarly journals The unfolded protein response in Pichia pastoris without external stressing stimuli

2020 ◽  
Vol 20 (7) ◽  
Author(s):  
Yasmin Nabilah Binti Mohd Fauzee ◽  
Naoki Taniguchi ◽  
Yuki Ishiwata-Kimata ◽  
Hiroshi Takagi ◽  
Yukio Kimata
Keyword(s):  
Pichia Pastoris ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Gene Knockout ◽  
Transmembrane Protein ◽  
Dependent Manner ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Stress Dependent ◽  
Protein Response

ABSTRACT Dysfunction or capacity shortage of the endoplasmic reticulum (ER) is cumulatively called ER stress and provokes the unfolded protein response (UPR). In various yeast species, the ER-located transmembrane protein Ire1 is activated upon ER stress and performs the splicing reaction of HAC1 mRNA, the mature form of which is translated into a transcription factor protein that is responsible for the transcriptome change on the UPR. Here we carefully assessed the splicing of HAC1 mRNA in Pichia pastoris (Komagataella phaffii) cells. We found that, inconsistent with previous reports by others, the HAC1 mRNA was substantially, but partially, spliced even without ER-stressing stimuli. Unlike Saccharomyces cerevisiae, growth of P. pastoris was significantly retarded by the IRE1-gene knockout mutation. Moreover, P. pastoris cells seemed to push more abundant proteins into the secretory pathway than S. cerevisiae cells. We also suggest that P. pastoris Ire1 has the ability to control its activity stringently in an ER stress-dependent manner. We thus propose that P. pastoris cells are highly ER-stressed possibly because of the high load of endogenous proteins into the ER.

scholarly journals ER-Phagy: A New Regulator of ER Homeostasis

2021 ◽  
Vol 9 ◽  
Author(s):  
Ming Yang ◽  
Shilu Luo ◽  
Xi Wang ◽  
Chenrui Li ◽  
Jinfei Yang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Cell Damage ◽  
External Stimulation ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Er Homeostasis ◽  
Cellular Organelles

The endoplasmic reticulum (ER) is one of the most important cellular organelles and is essential for cell homeostasis. Upon external stimulation, ER stress induces the unfolded protein response (UPR) and ER-associated degradation (ERAD) to maintain ER homeostasis. However, persistent ER stress can lead to cell damage. ER-phagy is a selective form of autophagy that ensures the timely removal of damaged ER, thereby protecting cells from damage caused by excessive ER stress. As ER-phagy is a newly identified form of autophagy, many receptor-mediated ER-phagy pathways have been discovered in recent years. In this review, we summarize our understanding of the maintenance of ER homeostasis and describe the receptors identified to date. Finally, the relationships between ER-phagy and diseases are also discussed.

scholarly journals MANF regulates unfolded protein response and neuronal survival through its ER-located receptor IRE1α

2020 ◽  
Author(s):  
Vera Kovaleva ◽  
Li-Ying Yu ◽  
Larisa Ivanova ◽  
Jinhan Nam ◽  
Ave Eesmaa ◽  
...  
Keyword(s):  
Er Stress ◽  
Unfolded Protein Response ◽  
Neuronal Cell ◽  
Direct Interaction ◽  
Cell Types ◽  
Dopamine Neurons ◽  
Unfolded Protein ◽  
Protein Response

AbstractMesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER)-located protein with cytoprotective effects in numerous cell types in vitro and in models of neurodegeneration and diabetes in vivo. So far, the exact mode of its action has remained elusive and plasma membrane or ER-located receptors of MANF have not been identified. We have found that MANF can directly interact with transmembrane unfolded protein response (UPR) receptor IRE1α and compete with the major ER chaperone BiP (GRP78) for the interaction with IRE1α. With lower affinities MANF can also interact with other UPR receptors, PERK and ATF6. Using molecular modeling and mutagenesis analysis, we have identified the exact structural MANF regions involved in its binding to the luminal domain of IRE1α. MANF attenuates UPR signaling by decreasing IRE1α oligomerization and IRE1α phosphorylation. MANF mutant deficient in IRE1α binding cannot regulate IRE1α oligomerization and fails to protect neurons from ER stress induced death. Importantly, we found that MANF-IRE1α interaction is also crucial for the survival promoting action of MANF for dopamine neurons in an animal model of Parkinson’s disease. Our data reveal a novel mechanism of IRE1α regulation during ER stress and demonstrate the intracellular mode of action of MANF as a modulator of UPR and neuronal cell survival through the direct interaction with IRE1α and regulation of its activity. Furthermore, our data explain why MANF in contrast to other growth factors has no effects on naive cells and rescues only ER stressed or injured cells.

Abstract P059: Cardiomyocyte Unfolded Protein Response Stimulates Autophagy

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Zhao V Wang ◽  
Thomas G Gillette ◽  
Beverly A Rothermel ◽  
Joseph A Hill
Keyword(s):  
Er Stress ◽  
Unfolded Protein Response ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Neonatal Rat ◽  
Autophagic Flux ◽  
Over Expression ◽  
Unfolded Protein ◽  
Protein Response

Background: Autophagy is an evolutionarily conserved process of protein and organelle recycling. Under basal conditions, autophagy is critical for protein and organelle quality control. This cannibalization mechanism, however, can be detrimental under certain conditions, and dysregulation of autophagy has been implicated in numerous diseases. Recently, activation of autophagic flux has been reported in cardiac hypertrophy, heart failure, myocardial infarction, and ischemia/reperfusion injury. The unfolded protein response (UPR) is a cellular mechanism triggered by folding stress in the ER. When protein folding capacity, governed by ER resident chaperones, is overwhelmed by misfolded proteins, ER stress ensues, stimulating chaperone protein expression, ER associated degradation, and ultimately cell death if the stress is not remediated. Recent studies in yeast suggest the UPR can directly activate autophagy by phosphorylating ATG1, a critical upstream kinase required during autophagy initiation. However, whether and how ER stress, which is active in cardiac disease, regulates autophagy in heart is unknown. Methods and Results: Using neonatal rat ventricular cardiomyocytes in culture, we found the classical ER stress inducer, tunicamycin, triggers profound UPR signaling and autophagy up-regulation. The processing of LC3-II, an indication of autophagy activity, is dramatically increased. As multiple pathways are involved in ER stress, we focused on the IRE1/XBP1 branch. With cardiomyocyte-specific over-expression by lentivirus in vitro, we observed robust activation of autophagy. Further, we found that in vivo over-expression of XBP1s in cardiomyocytes triggered autophagy, as evidenced by real-time PCR and immunoblotting assays. As autophagy markers can accumulate due to blockage of lysosomal degradation, we quantified the lysosomal proteins, cathepsin D and LAMP1, finding each to be increased, suggesting that autophagic activity and flux per se are enhanced. Conclusions: Taken together, our data suggest that the XBP1s arm of the UPR pathway activates autophagic gene expression, autophagosome assembly, and autophagic flux.

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