scholarly journals Glucocorticoid-activated IRE1α/XBP-1s signaling: an autophagy-associated protective pathway against endotheliocyte damage

2018 ◽  
Vol 315 (3) ◽  
pp. C300-C309 ◽  
Author(s):  
Yanchun Gao ◽  
Hongyi Zhu ◽  
Fan Yang ◽  
Qiyang Wang ◽  
Yong Feng ◽  
...  

Glucocorticoid-induced endothelial injury has been reported in several diseases. Although there are several theories, the exact mechanism underlying the role of glucocorticoids in this process remains unclear. Autophagy has been reported to occur as a response to different stimuli and can affect cell survival and function. In this study, we found that glucocorticoids induced apoptosis and endoplasmic reticulum (ER) stress in endotheliocytes. Furthermore, we discovered that glucocorticoids induced autophagy in these cells and the inositol requiring protein 1 (IRE1α)/X-box binding protein 1s (XBP-1s) axis, one of the downstream signaling pathways of ER stress, was associated with the glucocorticoid-induced autophagy. The autophagy partly protected endotheliocytes from glucocorticoid-induced apoptosis and inhibition of proliferation. In conclusion, glucocorticoid-induced endoplasmic reticulum stress activated the IRE1α/XBP-1s signaling and induced autophagy, which, in turn, played a protective role in endotheliocyte survival and proliferation, avoiding further cellular damage caused by glucocorticoids.

2021 ◽  
Author(s):  
Viorica Liebe Lastun ◽  
Matthew Freeman

In metazoans, the architecture of the endoplasmic reticulum (ER) differs between cell types, and undergoes major changes through the cell cycle and according to physiological needs. Although much is known about how the different ER morphologies are generated and maintained, especially the ER tubules, how context dependent changes in ER shape and distribution are regulated and the factors involved are less characterized. Here, we show that RHBDL4, an ER-resident rhomboid protease, modulates the shape and distribution of the ER, especially under conditions that require rapid changes in the ER sheet distribution, including ER stress. RHBDL4 interacts with CLIMP-63, a protein involved in ER sheet stabilisation, and with the cytoskeleton. Mice lacking RHBDL4 are sensitive to ER stress and develop liver steatosis, a phenotype associated with unresolved ER stress. Our data introduce a new physiological role of RHBDL4 and also imply that this function does not require its enzymatic activity.


2018 ◽  
Vol 1 (1) ◽  
pp. 94-108 ◽  
Author(s):  
Hyoung Yool Lee ◽  
Kyoungwhan Back

Melatonin has diverse roles as a signaling molecule that activates a number of downstream defense systems against various biotic and abiotic stresses in plants. However, there have been no reports regarding a direct protective role of melatonin against endoplasmic reticulum (ER) stress. Here, we report that exogenous melatonin treatment attenuated ER stress damage by preserving ER structure and enhancing secretory protein folding capacity in response to tunicamycin treatment. Further transgenic experiments indicated that melatonin-deficient snat1 mutant was hypersensitive to ER stress, whereas melatonin-proficient SNAT1 overexpression (OE) was tolerant to ER stress, as evidenced by reduced ion leakage and higher transcript levels of ER chaperones, including luminal binding protein (BIP) 2, BIP3, and CNX1, compared to wild-type controls. Moreover, this melatonin-mediated ER stress tolerance was dependent on the bZIP60 transcription factor and mitogen-activated protein kinase. Our data suggest that melatonin is actively involved in maintaining homeostasis of the ER during normal plant growth, and also has a protective effect against many environmental stressors that induce ER stress.


2011 ◽  
Vol 22 (6) ◽  
pp. 736-747 ◽  
Author(s):  
Etsushi Matsushita ◽  
Naoya Asai ◽  
Atsushi Enomoto ◽  
Yoshiyuki Kawamoto ◽  
Takuya Kato ◽  
...  

Continued exposure of endothelial cells to mechanical/shear stress elicits the unfolded protein response (UPR), which enhances intracellular homeostasis and protect cells against the accumulation of improperly folded proteins. Cells commit to apoptosis when subjected to continuous and high endoplasmic reticulum (ER) stress unless homeostasis is maintained. It is unknown how endothelial cells differentially regulate the UPR. Here we show that a novel Girdin family protein, Gipie (78 kDa glucose-regulated protein [GRP78]-interacting protein induced by ER stress), is expressed in endothelial cells, where it interacts with GRP78, a master regulator of the UPR. Gipie stabilizes the interaction between GRP78 and the ER stress sensor inositol-requiring protein 1 (IRE1) at the ER, leading to the attenuation of IRE1-induced c-Jun N-terminal kinase (JNK) activation. Gipie expression is induced upon ER stress and suppresses the IRE1-JNK pathway and ER stress-induced apoptosis. Furthermore we found that Gipie expression is up-regulated in the neointima of carotid arteries after balloon injury in a rat model that is known to result in the induction of the UPR. Thus our data indicate that Gipie/GRP78 interaction controls the IRE1-JNK signaling pathway. That interaction appears to protect endothelial cells against ER stress-induced apoptosis in pathological contexts such as atherosclerosis and vascular endothelial dysfunction.


2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Jianqiong Yang ◽  
Haiqing Liu ◽  
Linfu Li ◽  
Hai Liu ◽  
Weimei Shi ◽  
...  

Endoplasmic reticulum stress (ERS) has been demonstrated to exhibit a critical role in osteoarthritic chondrocytes. Whether 5,7,3′,4′-tetramethoxyflavone (TMF) plays the chondroprotective role in inhibition of PGE2-induced chondrocytes apoptosis associating with ERS has not been reported. To investigate this, the activation of PERK, ATF6, and IRE1 signaling pathways in ERS in chondrocytes pretreated with PGE2was studied. By treatment with PGE2, the chondrocytes apoptosis was significantly increased, the proapoptotic CHOP and JNK were upregulated, the prosurvival GRP78 and XBP1 were downregulated, and GSK-3βwas also upregulated. However, TMF exhibited the effectively protective functions via counteracting these detrimental effects of PGE2. Finally, the inflammatory cytokine PGE2can activate ERS signaling and promote chondrocytes apoptosis, which might be associated with upregulation of GSK-3β. TMF exhibits a chondroprotective role in inhibiting PGE2-induced ERS and GSK-3β.


RSC Advances ◽  
2016 ◽  
Vol 6 (111) ◽  
pp. 109639-109648 ◽  
Author(s):  
Yuying Feng ◽  
Liang Ma ◽  
Linfeng Liu ◽  
Hyokyoung Grace Hong ◽  
Xuemei Zhang ◽  
...  

Mechanism for the role of ER stress and oxidative stress activation in rhabdomyolysis-associated AKI.


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