Nonalcoholic fatty liver disease(NAFLD)has emerged as a common public health problem in recent decades.However,the underlying mechanisms leading to the development of NAFLD are not fully understood.The endoplasmic ret...Nonalcoholic fatty liver disease(NAFLD)has emerged as a common public health problem in recent decades.However,the underlying mechanisms leading to the development of NAFLD are not fully understood.The endoplasmic reticulum(ER)stress response has recently been proposed to play a crucial role in both the development of steatosis and progression to nonalcoholic steatohepatitis.ER stress is activated to regulate protein synthesis and restore homeostatic equilibrium when the cell is stressed due to the accumulation of unfolded or misfolded proteins.However,delayed or insufficient responses to ER stress may turn physiological mechanisms into pathological consequences,including fat accumulation,insulin resistance,inflammation,and apoptosis,all of which play important roles in the pathogenesis of NAFLD.Therefore,understanding the role of ER stress in the pathogenesis of NAFLD has become a topic of intense investigation.This review highlights the recent findings linking ER stress signaling pathways to the pathogenesis of NAFLD.展开更多
Protein folding in the endoplasmic reticulum （ER） is a fundamental process in plant cells that is vulnerable to many environmental stresses. When unfolded or misfolded proteins accumulate in the ER, the well-conserv...Protein folding in the endoplasmic reticulum （ER） is a fundamental process in plant cells that is vulnerable to many environmental stresses. When unfolded or misfolded proteins accumulate in the ER, the well-conserved unfolded protein response （UPR） is initiated to mitigate the ER stress by enhancing the protein folding capability and/or accelerating the ER-associated protein degradation. Here, we report the conservation of the activation mechanism of OsbZIP74 （also known as OsbZIP50）, an important ER stress regulator in monocot plant rice （Oryza sativa L.）. Under normal conditions, OsbZIP74 mRNA encodes a basic leucine-zipper transcription factor with a putative transmembrane domain. When treating with ER stress-inducing agents such as tunicamycin and DTT, the conserved double stem-loop structures of OsbZIP74 mRNA are spliced out. Thereafter, the resulting new OsbZIP74 mRNA produces the nucleus-localized form of OsbZIP74 protein, eliminating the hydrophobic region. The activated form of OsbZIP74 has transcriptional activation activity in both yeast cells and Arabidopsis leaf protoplasts. The induction of OsbZIP74 splicing is much suppressed in the OsIRE1 knock- down rice plants, indicating the involvement of OslRE1 in OsbZIP74 splicing. We also demonstrate that the unconventional splicing of OsbZIP74 mRNA is associated with heat stress and salicylic acid, which is an important plant hormone in systemic acquired resistance against pathogen or parasite.展开更多
Within the cell, several mechanisms exist to maintain homeostasis of the endoplasmic reticulum （ER）. One of the primary mechanisms is the unfolded protein response （UPR）. In this review, we primarily focus on the ...Within the cell, several mechanisms exist to maintain homeostasis of the endoplasmic reticulum （ER）. One of the primary mechanisms is the unfolded protein response （UPR）. In this review, we primarily focus on the latest signal webs and regulation mechanisms of the UPR. The relationships among ER stress, apoptosis, and cancer are also discussed. Under the normal state, binding immunoglobulin protein （BiP） interacts with the three sensors （protein kinase RNA-like ER kinase （PERK）, activating transcription factor 6 （ATF6）, and inositol-requiring enzyme la （IREla）） Under ER stress, misfolded proteins interact with BiP, resulting in the release of BiP from the sensors. Subsequently, the three sensors dimerize and autophosphorylate to promote the signal cascades of ER stress. ER stress includes a series of positive and negative feedback signals, such as those regulating the stabilization of the sensors/BiP complex, activating and inactivating the sensors by autophosphorylation and dephosphorylation, activating specific transcription factors to enable selective transcription, and augmenting the ability to refold and export. Apart from the three basic pathways, vascular endothelial growth factor （VEGF）-VEGF receptor （VEGFR）-phospholipase C-~ （PLCy）-mammalian target of rapamycin complex 1 （mTORC1） pathway, induced only in solid tumors, can also activate ATF6 and PERK signal cascades, and IREla also can be activated by activated RAC-alpha serine/threonine-protein kinase （AKT）. A moderate UPR functions as a pro-survival signal to return the cell to its state of homeostasis. However, persistent ER stress will induce cells to undergo apoptosis in response to increasing reactive oxygen species （ROS）, Ca2＋ in the cytoplasmic matrix, and other apoptosis signal cascades, such as c-Jun N-terminal kinase （JNK）, signal transducer and activator of transcription 3 （STAT3）, and P38, when cellular damage exceeds the capacity of this adaptive response.展开更多
The membrane-associated transcription factor, bZlP28, is relocated from the endoplasmic reticulum （ER） to the Golgi and proteolytically released from the membrane mediated by two proteases, SlP and S2P, in response ...The membrane-associated transcription factor, bZlP28, is relocated from the endoplasmic reticulum （ER） to the Golgi and proteolytically released from the membrane mediated by two proteases, SlP and S2P, in response to ER stress in Arabidopsis. The activated N-terminal domain recruits nuclear factor Y （NF-Y） subunits in the nucleus to regulate ER stress downstream genes. Little is known about the functions of the bZIP28 C-terminal lumen-facing domain. Here, we provide novel insights into how the ER lumen-facing domain affects the biological function and organelle-to-organelle movement of bZIP28 in the ER stress response. First, we demonstrated the functional redundancy of bZlP28 and bZIP60 by generation and analysis of the bZIP28 and bZIP60 double mutant zip28zip60. Subsequent genetic complementation experiments in zip28zip60 background with deletions on bZlP28 lumen-facing domain highlighted the importance of lumen-facing domain for its in vivo function of bZIP28 in the ER stress response. The protein subcellular localization and Western blotting results further revealed that the bZIP28 lumen-facing domain contains ER retention signal which is important for the proteolytic activation of bZIP28. Thus, the bZIP28 lumen-facing C-terminus plays important roles in the ER-to-Golgi movement of bZlP28, which may contribute to the sensing of the ER stress.展开更多
Inhibitors of protein deacetylases have recently been established as a novel therapeutic principle for several human diseases,including cancer.The original notion of the mechanism of action of these compounds focused ...Inhibitors of protein deacetylases have recently been established as a novel therapeutic principle for several human diseases,including cancer.The original notion of the mechanism of action of these compounds focused on the epigenetic control of transcriptional processes, especially of tumor suppressor genes,by interfering with the acetylation status of nuclear histone proteins,hence the name histone deacetylase inhibitors was coined.Yet,this view could not explain the high specificity for tumor cells and recent evidence now suggests that non-histone proteins represent major targets for protein deacetylase inhibitors and that the post-translational modification of the acetylome is involved in various cellular processes of differentiation,survival and cell death induction.展开更多
Many sources of stress cause accumulation of unfolded or misfolded proteins in endoplasmic reticulum(ER), which elicits the unfolded protein response(UPR) to either promote cell survival or programmed cell death depen...Many sources of stress cause accumulation of unfolded or misfolded proteins in endoplasmic reticulum(ER), which elicits the unfolded protein response(UPR) to either promote cell survival or programmed cell death depending on different developmental context or stress severity. The Arabidopsis membrane-associated transcription factor, b ZIP28, is the functional equivalent of mammalian ATF6, which relocates from the ER to the Golgi where it is proteolytically processed and released from the membrane to the nucleus to mediate the UPR. Although the canonical site-1 protease(S1P) cleavage site on the ER lumen-facing domain is well conserved between b ZIP28 and ATF6, the importance of S1 P cleavage on b ZIP28 has not been experimentally demonstrated. Here we provide genetic evidence that the RRIL573 site, but not the RVLM373 site, on the lumen-facing domain of bZ IP28 is critical for the biological function of b ZIP28 under ER stress condition. Further biochemistry and cell biology studies demonstrated that the RRIL573 site, but not the RVLM373 site, is required for proteolytic processing and nuclear relocation of b ZIP28 in response to ER stress. Our results reveal that S1 P cleavage site plays a pivotal role in activation and function of b ZIP28 during UPR in plants.展开更多
Cadmium （Cd） is a reproductive toxicant that induces germ cell apoptosis in the testes. Previous studies have demonstrated that endoplasmic reticulum （ER） stress is involved in Cd-induced germ cell apoptosis. The ...Cadmium （Cd） is a reproductive toxicant that induces germ cell apoptosis in the testes. Previous studies have demonstrated that endoplasmic reticulum （ER） stress is involved in Cd-induced germ cell apoptosis. The aim of the present study was to investigate the effects of N-acetylcysteine （NAC）, an antioxidant, on Cd-induced ER stress and germ cell apoptosis in the testes. Male CD-1 mice were intraperitoneally injected with CdCl2 （2.0 mg kg^-1）. As expected, acute Cd exposure induced germ cell apoptosis in the testes, as determined by terminal dUTP nick-end labelling （TUNEL）. However, the administration of NAC alleviated Cd-induced germ ceil apoptosis in the testes. Further analysis showed that NAC attenuated the Cd-induced upregulation of testicular glucose-regulated protein 78 （GRP78）, an important ER molecular chaperone. Moreover, NAC inhibited the Cd-induced phosphorylation of testicular eukaryotic translation initiation factor 2a （elF2a）, a downstream target of the double-stranded RNA-activated kinase-like ER kinase （PERK） pathway. In addition, NAC blocked the Cd-induced activation of testicular X binding protein （XBP）-1, indicating that NAC attenuates the Cd-induced ER stress and the unfolded protein response （UPR）. Interestingly, NAC almost completely prevented the Cd-induced elevation of C/EBP homologous protein （CHOP） and phosphorylation of c-Jun N-terminal kinase （.INK）, two components of the ER stress-mediated apoptotic pathway. In conclusion, NAC protects against Cd-induced germ cell apoptosis by inhibiting endoplasmic reticulum stress in the testes.展开更多
Objectives： To investigate the role of prolyl 4-hydroxylase beta polypeptide （P4HB） expressed in lung carcinoma and the intervention effect of Yiqi Chutan Formula （益气除痰方, YQCTF）. Methods： Lung carcinoma mod...Objectives： To investigate the role of prolyl 4-hydroxylase beta polypeptide （P4HB） expressed in lung carcinoma and the intervention effect of Yiqi Chutan Formula （益气除痰方, YQCTF）. Methods： Lung carcinoma model was established by subcutaneously inoculating LEWIS lung carcinoma cells in C57BL/6J mice. The differential expression of P4HB protein between the YQCTF （3.0 g/kg, gavage, once daily, 21 days） group and the control group was acquired by a 2 fluorescence difference gel electrophoresis （2D-DIGE）, verified by Westem blotting and identified by matrix-assisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF/＇IOF-MS）. The expression of P4HB and P4HB mRNA in cultured A549 cells from cisplatin （DDP） 1.5μg/mL group and 15% serum combined with DDP 1.5 μg/mL group were detected by cellular immunohistochemistry and reverse chain reaction, respectively. Results： The proteomics research discovered that one-third of differential proteins including P4HB were decreased in the YQCTF group （P〈0.01）. Clinical pathology and tissue microarray studies showed that P4HB expression in lung cancer tissue was stronger than adjacent tissues and normal lung epithelial （P〈0.01）. In the YQCTF and DDP combined groups, the expression of P4HB and P4HB mRNA in A549 cell were decreased significantly （P〈0.01）. Conclusion： YQCTF could inhibit the LEWIS lung carcinoma＇s growth, decrease the expression of P4HB in LEWIS lung carcinoma and A549 cells. YQCTF might take effect through regulating P4HB in endoplasmic reticulum to inhibit the incidence and growth process of lung cercinoma.展开更多
Acute pancreatitis (AP) is an inflammatory disorder of pancreatic tissue initiated in injured acinar cells. Severe AP remains a significant challenge due to the lack of effective treatment. The widely-accepted autodig...Acute pancreatitis (AP) is an inflammatory disorder of pancreatic tissue initiated in injured acinar cells. Severe AP remains a significant challenge due to the lack of effective treatment. The widely-accepted autodigestion theory of AP is now facing challenges, since inhibiting protease activation has negligible effectiveness for AP treatment despite numerous efforts. Furthermore, accumulating evidence supports a new concept that malfunction of a self-protective mechanism, the unfolded protein response(UPR), is the driving force behind the pathogenesis of AP. The UPR is induced by endoplasmic reticulum(ER) stress, a disturbance frequently found in acinar cells, to prevent the aggravation of ER stress that can otherwise lead to cell injury. In addition, the UPR's signaling pathways control NFκB activation and autophagy flux, and these dysregulations cause acinar cell inflammatory injury in AP, but with poorly understood mechanisms. We therefore summarize the protective role of the UPR in AP, propose mechanistic models of how inadequate UPR could promote NFκB's pro-inflammatory activity and impair autophagy's protective function in acinar cells, and discuss its relevance to current AP treatment. We hope that insight provided in this review will help facilitate the research and management of AP.展开更多
Hepatitis B virus(HBV) is a non-cytopathic virus that causes acute and chronic inflammatory liver diseases,often leading to the pathogenesis of hepatocellular carcinoma(HCC). Although many studies for the roles of HBV...Hepatitis B virus(HBV) is a non-cytopathic virus that causes acute and chronic inflammatory liver diseases,often leading to the pathogenesis of hepatocellular carcinoma(HCC). Although many studies for the roles of HBV on pathogenesis of the liver diseases,such as non-alcoholic fatty liver disease(NAFLD),hepatic inflammation,cirrhosis,and HCC,have been reported,the mechanisms are not fully understood. Endoplasmic reticulum(ER) and mitochondria have the protective mechanisms to restore their damaged function by intrinsic or extrinsic stresses,but their chronic dysfunctions are associated with the pathogenesis of the various diseases. Furthermore,HBV can affect intraor extracellular homeostasis through induction of ER and mitochondrial dysfunctions,leading to liver injury. Therefore,the mechanism by which HBV induces ER or mitochondrial stresses may be a therapeutic target for treatment of liver diseases.展开更多
Apoptosis after traumatic brain injury has been shown to be a major factor influencing prognosis and outcome. Endoplasmic reticulum stress may be involved in mitochondrial mediated neuronal apoptosis. Therefore, endop...Apoptosis after traumatic brain injury has been shown to be a major factor influencing prognosis and outcome. Endoplasmic reticulum stress may be involved in mitochondrial mediated neuronal apoptosis. Therefore, endoplasmic reticulum stress has become an important mechanism of secondary injury after traumatic brain injury. In this study, a rat model of traumatic brain injury was established by lateral fluid percussion injury. Fluorescence assays were used to measure reactive oxygen species content in the cerebral cortex. Western blot assays were used to determine expression of endoplasmic reticulum stress-related proteins. Hematoxylin-eosin staining was used to detect pathological changes in the cerebral cortex. Transmission electron microscopy was used to measure ultrastructural changes in the endoplasmic reticulum and mitochondria. Our results showed activation of the endoplasmic reticulum stress-related unfolded protein response. Meanwhile, both the endoplasmic reticulum stress response and mitochondrial apoptotic pathway were activated at different stages post-traumatic brain injury. Furthermore, pretreatment with the endoplasmic reticulum stress inhibitor, salubrinal（1 mg/kg）, by intraperitoneal injection 30 minutes before injury significantly inhibited the endoplasmic reticulum stress response and reduced apoptosis. Moreover, salubrinal promoted recovery of mitochondrial function and inhibited activation of the mitochondrial apoptotic pathway post-traumatic brain injury. These results suggest that endoplasmic reticulum stress might be a key factor for secondary brain injury post-traumatic brain injury.展开更多
Objective Autophagy is a highly conserved intracellular degradation pathway. Many picornaviruses induce autophagy to benefit viral replication, but an understanding of how autophagy occurs remains incomplete. In this ...Objective Autophagy is a highly conserved intracellular degradation pathway. Many picornaviruses induce autophagy to benefit viral replication, but an understanding of how autophagy occurs remains incomplete. In this study, we explored whether coxsackievirus B3(CVB3) infection induced autophagy through endoplasmic reticulum(ER) stress. Methods In CVB3-infected HeLa cells, the specific molecules of ER stress and autophagy were detected using Western blotting, reverse transcription polymerase chain reaction(RT-PCR), and confocal microscopy. Then PKR-like ER protein kinase(PERK) inhibitor, inositol-requiring protein-1(IRE1) inhibitor, or activating transcription factor-6(ATF6) inhibitor worked on CVB3-infected cells, their effect on autophagy was assessed by Western blotting for detecting microtubule-associated protein light chain 3(LC3). Results CVB3 infection induced ER stress, and ER stress sensors PERK/eIF2α, IRE1/XBP1, and ATF6 were activated. CVB3 infection increased the accumulation of green fluorescent protein(GFP)-LC3 punctuation and induced the conversion from LC3-Ⅰ to phosphatidylethanolamine-conjugated LC3-1(LC3-Ⅱ). CVB3 infection still decreased the expression of mammalian target of rapamycin(mTOR) and p-mTOR. Inhibition of PERK, IRE1, or ATF6 significantly decreased the ratio of LC3-Ⅱ to LC3-Ⅰ in CVB3-infected HeLa cells. Conclusion CVB3 infection induced autophagy through ER stress in HeL a cells, and PERK, IRE1, and ATF6 a pathways participated in the regulation of autophagy. Our data suggested that ER stress may inhibit mTOR signaling pathway to induce autophagy during CVB3 infection.展开更多
Abrus mollis is a widely used traditional Chinese medicine for treating acute and chronic hepatitis, steatosis, and fibrosis. It was found that the total flavonoid C-glycosides from Abrus mollis extract(AME) showed po...Abrus mollis is a widely used traditional Chinese medicine for treating acute and chronic hepatitis, steatosis, and fibrosis. It was found that the total flavonoid C-glycosides from Abrus mollis extract(AME) showed potent antioxidant, anti-inflammatory, and hepatoprotective activities. To further investigate the hepatoprotective effect of AME and its possible mechanisms, lipopolysaccharide(LPS)-induced liver injury models were applied in the current study. The results indicated that AME significantly attenuated LPS-induced lipid accumulation in mouse primary hepatocytes as measured by triglyceride(TG) and total cholesterol(TC) assays and Oil Red O staining. Meanwhile, AME exerted a protective effect on LPS-induced liver injury as shown by decreased liver index, serum aminotransferase levels, and hepatic lipid accumulation. Real-time PCR and immunoblot data suggested that AME reversed the LPS-mediated lipid metabolism gene expression, such as sterol regulatory element-binding protein-1(SREBP-1), fatty acid synthase(FAS), and acetyl-CoA carboxylase 1(ACC1). In addition, LPS-induced overexpression of activating transcription factor 4(ATF4), X-box-binding protein-1(XBP-1), and C/EBP homologous protein(CHOP) were dramatically reversed by AME. Furthermore, AME also decreased the expression of LPS-enhanced interleukin-6(IL-6) and cyclooxygenase-2(COX-2). Here, it is demonstrated for the first time that AME ameliorated LPS-induced hepatic lipid accumulation and that this effect of AME can be attributed to its modulation of hepatic de novo fatty acid synthesis. This study also suggested that the hepatoprotective effect of AME may be related to its down-regulation of unfolded protein response(UPR) activation.展开更多
The endoplasmic reticulum,chloroplasts,and mitochondria are major plant organelles for protein synthesis,photosynthesis,metabolism,and energy production.Protein homeostasis in these organelles,maintained by a balance ...The endoplasmic reticulum,chloroplasts,and mitochondria are major plant organelles for protein synthesis,photosynthesis,metabolism,and energy production.Protein homeostasis in these organelles,maintained by a balance between protein synthesis and degradation,is essential for cell functions during plant growth,development,and stress resistance.Nucleus-encoded chloroplast-and mitochondrion-targeted proteins and ER-resident proteins are imported from the cytosol and undergo modification and maturation within their respective organelles.Protein folding is an error-prone process that is influenced by both developmental signals and environmental cues;a number of mechanisms have evolved to ensure efficient import and proper folding and maturation of proteins in plant organelles.Misfolded or damaged proteins with nonnative conformations are subject to degradation via complementary or competing pathways:intraorganelle proteases,the organelle-associated ubiquitin-proteasome system,and the selective autophagy of partial or entire organelles.When proteins in nonnative conformations accumulate,the organellespecific unfolded protein response operates to restore protein homeostasis by reducing protein folding demand,increasing protein folding capacity,and enhancing components involved in proteasome-associated protein degradation and autophagy.This review summarizes recent progress on the understanding of protein quality control in the ER,chloroplasts,and mitochondria in plants,with a focus on common mechanisms shared by these organelles during protein homeostasis.展开更多
Background： Amyloid β （Aβ） deposits and the endoplasmic reticulum stress （ERS） are both well established in the development and progression of Alzheimer＇s disease （AD）. However, the mechanism and role of Aβ...Background： Amyloid β （Aβ） deposits and the endoplasmic reticulum stress （ERS） are both well established in the development and progression of Alzheimer＇s disease （AD）. However, the mechanism and role of Aβ-induced ERS in AD-associated pathological progression remain to be elucidated. Methods： The five familial AD （5×FAD） mice and wild-type （WT） mice aged 2, 7, and 12 months were used in the present study. Monis water maze test was used to evaluate their cognitive performance, lmmunofluorescence and Western blot analyses were used to examine the dynamic changes of pro-apoptotic （CCAAT/enhancer-binding protein homologous protein [CHOP] and cleaved caspase-12） and anti-apoptotic factors （chaperone glucose-regulated protein [GRP] 78 and endoplasmic reticulum-associated protein degradation-associated ubiquitin ligase synovial apoptosis inhibitor 1 [SYVN 1]） in the ERS-associated unfolded protein response （UPR） pathway. Results： Compared with age-matched WT mice, 5 xFAD mice showed higher cleaved caspase-3, lower neuron-positive staining at the age of 12 months, but earlier cognitive deficit at the age of 7 months （all P 〈 0.05）. Interestingly, for 2-month-old 5×FAD mice, the related proteins involved in the ERS-associated UPR pathway, including CHOP, cleaved caspase-12, GRP 78, and SYVN 1, were significantly increased when compared with those in age-matched WT mice （all P 〈 0.05）. Moreover, ERS occurred mainly in neurons, not in astrocytes. Conclusions： These findings suggest that compared with those of age-matched WT mice, ERS-associated pro-apoptotic and anti-apoptotic proteins are upregulated in 2-month-old 5×FAD mice, consistent with intracellular Aβ aggregation in neurons.展开更多
基金Supported by National Key Basic Research Development Program,No.2012CB524905National Science and Technology Support Plan Project,No.2012BAI06B04+4 种基金National Natural Science Foundation of China,No.30900677,No.81070315,No.81070366,No.81100278,No.81170378,No.81230012 and No.81270487Zhejiang Provincial Natural Science Foundation of China,No.Y2090463 and No.Y2110026International Science and Technology Cooperation Projects of Zhejiang Province,No.2013C24010Science Foundation of Health Bureau of Zhejiang Province,No.2009A070 and No.2012RCA026Specialized Research Fund for the Doctoral Program of Higher Education,No.20090101120110
文摘Nonalcoholic fatty liver disease(NAFLD)has emerged as a common public health problem in recent decades.However,the underlying mechanisms leading to the development of NAFLD are not fully understood.The endoplasmic reticulum(ER)stress response has recently been proposed to play a crucial role in both the development of steatosis and progression to nonalcoholic steatohepatitis.ER stress is activated to regulate protein synthesis and restore homeostatic equilibrium when the cell is stressed due to the accumulation of unfolded or misfolded proteins.However,delayed or insufficient responses to ER stress may turn physiological mechanisms into pathological consequences,including fat accumulation,insulin resistance,inflammation,and apoptosis,all of which play important roles in the pathogenesis of NAFLD.Therefore,understanding the role of ER stress in the pathogenesis of NAFLD has become a topic of intense investigation.This review highlights the recent findings linking ER stress signaling pathways to the pathogenesis of NAFLD.
基金This project is funded by the National Natural Science Foundation of China （31070233, 31171157）, Shanghai Pujiang Talent Program （11PJ1400700）, and partly supported by the National Basic Research Program of China （973 Program, 2012CB910500）, all granted to J.X.L. ACKNOWLEDGMENTS We would also like thank Drs Yuhya Wakasa and Fumio Takaiwa for providing the OslREI transgenic rice seeds. No conflict of interest declared.
文摘Protein folding in the endoplasmic reticulum （ER） is a fundamental process in plant cells that is vulnerable to many environmental stresses. When unfolded or misfolded proteins accumulate in the ER, the well-conserved unfolded protein response （UPR） is initiated to mitigate the ER stress by enhancing the protein folding capability and/or accelerating the ER-associated protein degradation. Here, we report the conservation of the activation mechanism of OsbZIP74 （also known as OsbZIP50）, an important ER stress regulator in monocot plant rice （Oryza sativa L.）. Under normal conditions, OsbZIP74 mRNA encodes a basic leucine-zipper transcription factor with a putative transmembrane domain. When treating with ER stress-inducing agents such as tunicamycin and DTT, the conserved double stem-loop structures of OsbZIP74 mRNA are spliced out. Thereafter, the resulting new OsbZIP74 mRNA produces the nucleus-localized form of OsbZIP74 protein, eliminating the hydrophobic region. The activated form of OsbZIP74 has transcriptional activation activity in both yeast cells and Arabidopsis leaf protoplasts. The induction of OsbZIP74 splicing is much suppressed in the OsIRE1 knock- down rice plants, indicating the involvement of OslRE1 in OsbZIP74 splicing. We also demonstrate that the unconventional splicing of OsbZIP74 mRNA is associated with heat stress and salicylic acid, which is an important plant hormone in systemic acquired resistance against pathogen or parasite.
基金Project supported by the National Basic Research Program(973)of China(No.2012CB518900)the National Natural Science Foundation of China(Nos.31160240 and 31260621)+2 种基金the National Major Scientific and Technological Special Project during the Twelfth Five-year Plan Period of China(No.2012ZX10002006)the Hangzhou Normal University Supporting Project(No.PE13002004042)the Natural Science Foundation of Jiangxi Province(No.20114BAB204016),China
文摘Within the cell, several mechanisms exist to maintain homeostasis of the endoplasmic reticulum （ER）. One of the primary mechanisms is the unfolded protein response （UPR）. In this review, we primarily focus on the latest signal webs and regulation mechanisms of the UPR. The relationships among ER stress, apoptosis, and cancer are also discussed. Under the normal state, binding immunoglobulin protein （BiP） interacts with the three sensors （protein kinase RNA-like ER kinase （PERK）, activating transcription factor 6 （ATF6）, and inositol-requiring enzyme la （IREla）） Under ER stress, misfolded proteins interact with BiP, resulting in the release of BiP from the sensors. Subsequently, the three sensors dimerize and autophosphorylate to promote the signal cascades of ER stress. ER stress includes a series of positive and negative feedback signals, such as those regulating the stabilization of the sensors/BiP complex, activating and inactivating the sensors by autophosphorylation and dephosphorylation, activating specific transcription factors to enable selective transcription, and augmenting the ability to refold and export. Apart from the three basic pathways, vascular endothelial growth factor （VEGF）-VEGF receptor （VEGFR）-phospholipase C-~ （PLCy）-mammalian target of rapamycin complex 1 （mTORC1） pathway, induced only in solid tumors, can also activate ATF6 and PERK signal cascades, and IREla also can be activated by activated RAC-alpha serine/threonine-protein kinase （AKT）. A moderate UPR functions as a pro-survival signal to return the cell to its state of homeostasis. However, persistent ER stress will induce cells to undergo apoptosis in response to increasing reactive oxygen species （ROS）, Ca2＋ in the cytoplasmic matrix, and other apoptosis signal cascades, such as c-Jun N-terminal kinase （JNK）, signal transducer and activator of transcription 3 （STAT3）, and P38, when cellular damage exceeds the capacity of this adaptive response.
基金This study was financially supported by grants from the National Basic Research Program of China （973 Program, 2012CB910500）, the National Natural Science Foundation of China （#31171157 #31070233 #31222008）, and the Shanghai Pujiang Talent Program （11PJ1400700）. No conflict of interest declared.
文摘The membrane-associated transcription factor, bZlP28, is relocated from the endoplasmic reticulum （ER） to the Golgi and proteolytically released from the membrane mediated by two proteases, SlP and S2P, in response to ER stress in Arabidopsis. The activated N-terminal domain recruits nuclear factor Y （NF-Y） subunits in the nucleus to regulate ER stress downstream genes. Little is known about the functions of the bZIP28 C-terminal lumen-facing domain. Here, we provide novel insights into how the ER lumen-facing domain affects the biological function and organelle-to-organelle movement of bZIP28 in the ER stress response. First, we demonstrated the functional redundancy of bZlP28 and bZIP60 by generation and analysis of the bZIP28 and bZIP60 double mutant zip28zip60. Subsequent genetic complementation experiments in zip28zip60 background with deletions on bZlP28 lumen-facing domain highlighted the importance of lumen-facing domain for its in vivo function of bZIP28 in the ER stress response. The protein subcellular localization and Western blotting results further revealed that the bZIP28 lumen-facing domain contains ER retention signal which is important for the proteolytic activation of bZIP28. Thus, the bZIP28 lumen-facing C-terminus plays important roles in the ER-to-Golgi movement of bZlP28, which may contribute to the sensing of the ER stress.
基金Supported by Supported by a Research Grant of the University Medical Center Giessen and Marburg
文摘Inhibitors of protein deacetylases have recently been established as a novel therapeutic principle for several human diseases,including cancer.The original notion of the mechanism of action of these compounds focused on the epigenetic control of transcriptional processes, especially of tumor suppressor genes,by interfering with the acetylation status of nuclear histone proteins,hence the name histone deacetylase inhibitors was coined.Yet,this view could not explain the high specificity for tumor cells and recent evidence now suggests that non-histone proteins represent major targets for protein deacetylase inhibitors and that the post-translational modification of the acetylome is involved in various cellular processes of differentiation,survival and cell death induction.
基金supported by grants from the National Basic Research Program of China(973 Program,2012CB910500)the National Natural Science Foundation of China(31171157,31222008)the Specialized Research Fund for the Doctoral Program of Higher Education(20130071110011)
文摘Many sources of stress cause accumulation of unfolded or misfolded proteins in endoplasmic reticulum(ER), which elicits the unfolded protein response(UPR) to either promote cell survival or programmed cell death depending on different developmental context or stress severity. The Arabidopsis membrane-associated transcription factor, b ZIP28, is the functional equivalent of mammalian ATF6, which relocates from the ER to the Golgi where it is proteolytically processed and released from the membrane to the nucleus to mediate the UPR. Although the canonical site-1 protease(S1P) cleavage site on the ER lumen-facing domain is well conserved between b ZIP28 and ATF6, the importance of S1 P cleavage on b ZIP28 has not been experimentally demonstrated. Here we provide genetic evidence that the RRIL573 site, but not the RVLM373 site, on the lumen-facing domain of bZ IP28 is critical for the biological function of b ZIP28 under ER stress condition. Further biochemistry and cell biology studies demonstrated that the RRIL573 site, but not the RVLM373 site, is required for proteolytic processing and nuclear relocation of b ZIP28 in response to ER stress. Our results reveal that S1 P cleavage site plays a pivotal role in activation and function of b ZIP28 during UPR in plants.
基金ACKNOWLEDGMENTS This project was supported by the National Natural Science Foundation of China （No. 31000664） and Grants for Scientific Research of BSKY （No. XJ201114） and the Program of Young Top-Notch Talents from Anhui Medical University.
文摘Cadmium （Cd） is a reproductive toxicant that induces germ cell apoptosis in the testes. Previous studies have demonstrated that endoplasmic reticulum （ER） stress is involved in Cd-induced germ cell apoptosis. The aim of the present study was to investigate the effects of N-acetylcysteine （NAC）, an antioxidant, on Cd-induced ER stress and germ cell apoptosis in the testes. Male CD-1 mice were intraperitoneally injected with CdCl2 （2.0 mg kg^-1）. As expected, acute Cd exposure induced germ cell apoptosis in the testes, as determined by terminal dUTP nick-end labelling （TUNEL）. However, the administration of NAC alleviated Cd-induced germ ceil apoptosis in the testes. Further analysis showed that NAC attenuated the Cd-induced upregulation of testicular glucose-regulated protein 78 （GRP78）, an important ER molecular chaperone. Moreover, NAC inhibited the Cd-induced phosphorylation of testicular eukaryotic translation initiation factor 2a （elF2a）, a downstream target of the double-stranded RNA-activated kinase-like ER kinase （PERK） pathway. In addition, NAC blocked the Cd-induced activation of testicular X binding protein （XBP）-1, indicating that NAC attenuates the Cd-induced ER stress and the unfolded protein response （UPR）. Interestingly, NAC almost completely prevented the Cd-induced elevation of C/EBP homologous protein （CHOP） and phosphorylation of c-Jun N-terminal kinase （.INK）, two components of the ER stress-mediated apoptotic pathway. In conclusion, NAC protects against Cd-induced germ cell apoptosis by inhibiting endoplasmic reticulum stress in the testes.
基金Supported by the National Natural Science Fundation of China(No.30772862)Guangdong Natural Science Fund(No.2010-3)Project of Guangdong University Talent Fund(No.2010-79)
文摘Objectives： To investigate the role of prolyl 4-hydroxylase beta polypeptide （P4HB） expressed in lung carcinoma and the intervention effect of Yiqi Chutan Formula （益气除痰方, YQCTF）. Methods： Lung carcinoma model was established by subcutaneously inoculating LEWIS lung carcinoma cells in C57BL/6J mice. The differential expression of P4HB protein between the YQCTF （3.0 g/kg, gavage, once daily, 21 days） group and the control group was acquired by a 2 fluorescence difference gel electrophoresis （2D-DIGE）, verified by Westem blotting and identified by matrix-assisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF/＇IOF-MS）. The expression of P4HB and P4HB mRNA in cultured A549 cells from cisplatin （DDP） 1.5μg/mL group and 15% serum combined with DDP 1.5 μg/mL group were detected by cellular immunohistochemistry and reverse chain reaction, respectively. Results： The proteomics research discovered that one-third of differential proteins including P4HB were decreased in the YQCTF group （P〈0.01）. Clinical pathology and tissue microarray studies showed that P4HB expression in lung cancer tissue was stronger than adjacent tissues and normal lung epithelial （P〈0.01）. In the YQCTF and DDP combined groups, the expression of P4HB and P4HB mRNA in A549 cell were decreased significantly （P〈0.01）. Conclusion： YQCTF could inhibit the LEWIS lung carcinoma＇s growth, decrease the expression of P4HB in LEWIS lung carcinoma and A549 cells. YQCTF might take effect through regulating P4HB in endoplasmic reticulum to inhibit the incidence and growth process of lung cercinoma.
文摘Acute pancreatitis (AP) is an inflammatory disorder of pancreatic tissue initiated in injured acinar cells. Severe AP remains a significant challenge due to the lack of effective treatment. The widely-accepted autodigestion theory of AP is now facing challenges, since inhibiting protease activation has negligible effectiveness for AP treatment despite numerous efforts. Furthermore, accumulating evidence supports a new concept that malfunction of a self-protective mechanism, the unfolded protein response(UPR), is the driving force behind the pathogenesis of AP. The UPR is induced by endoplasmic reticulum(ER) stress, a disturbance frequently found in acinar cells, to prevent the aggravation of ER stress that can otherwise lead to cell injury. In addition, the UPR's signaling pathways control NFκB activation and autophagy flux, and these dysregulations cause acinar cell inflammatory injury in AP, but with poorly understood mechanisms. We therefore summarize the protective role of the UPR in AP, propose mechanistic models of how inadequate UPR could promote NFκB's pro-inflammatory activity and impair autophagy's protective function in acinar cells, and discuss its relevance to current AP treatment. We hope that insight provided in this review will help facilitate the research and management of AP.
基金Supported by the National Research Foundation of South Korea,No.NRF-2009-0093195Basic Science Research Program through the NRF funded by the Ministry of Education,No.NRF-2013R1A1A2057634
文摘Hepatitis B virus(HBV) is a non-cytopathic virus that causes acute and chronic inflammatory liver diseases,often leading to the pathogenesis of hepatocellular carcinoma(HCC). Although many studies for the roles of HBV on pathogenesis of the liver diseases,such as non-alcoholic fatty liver disease(NAFLD),hepatic inflammation,cirrhosis,and HCC,have been reported,the mechanisms are not fully understood. Endoplasmic reticulum(ER) and mitochondria have the protective mechanisms to restore their damaged function by intrinsic or extrinsic stresses,but their chronic dysfunctions are associated with the pathogenesis of the various diseases. Furthermore,HBV can affect intraor extracellular homeostasis through induction of ER and mitochondrial dysfunctions,leading to liver injury. Therefore,the mechanism by which HBV induces ER or mitochondrial stresses may be a therapeutic target for treatment of liver diseases.
文摘Apoptosis after traumatic brain injury has been shown to be a major factor influencing prognosis and outcome. Endoplasmic reticulum stress may be involved in mitochondrial mediated neuronal apoptosis. Therefore, endoplasmic reticulum stress has become an important mechanism of secondary injury after traumatic brain injury. In this study, a rat model of traumatic brain injury was established by lateral fluid percussion injury. Fluorescence assays were used to measure reactive oxygen species content in the cerebral cortex. Western blot assays were used to determine expression of endoplasmic reticulum stress-related proteins. Hematoxylin-eosin staining was used to detect pathological changes in the cerebral cortex. Transmission electron microscopy was used to measure ultrastructural changes in the endoplasmic reticulum and mitochondria. Our results showed activation of the endoplasmic reticulum stress-related unfolded protein response. Meanwhile, both the endoplasmic reticulum stress response and mitochondrial apoptotic pathway were activated at different stages post-traumatic brain injury. Furthermore, pretreatment with the endoplasmic reticulum stress inhibitor, salubrinal（1 mg/kg）, by intraperitoneal injection 30 minutes before injury significantly inhibited the endoplasmic reticulum stress response and reduced apoptosis. Moreover, salubrinal promoted recovery of mitochondrial function and inhibited activation of the mitochondrial apoptotic pathway post-traumatic brain injury. These results suggest that endoplasmic reticulum stress might be a key factor for secondary brain injury post-traumatic brain injury.
基金supported by the China Mega-project for Infectious Disease [2018ZX10102001,2018ZX10711001,2018ZX10734401,and 2018ZX10734404]the SKLID Development Grant [2011SKLID104]
文摘Objective Autophagy is a highly conserved intracellular degradation pathway. Many picornaviruses induce autophagy to benefit viral replication, but an understanding of how autophagy occurs remains incomplete. In this study, we explored whether coxsackievirus B3(CVB3) infection induced autophagy through endoplasmic reticulum(ER) stress. Methods In CVB3-infected HeLa cells, the specific molecules of ER stress and autophagy were detected using Western blotting, reverse transcription polymerase chain reaction(RT-PCR), and confocal microscopy. Then PKR-like ER protein kinase(PERK) inhibitor, inositol-requiring protein-1(IRE1) inhibitor, or activating transcription factor-6(ATF6) inhibitor worked on CVB3-infected cells, their effect on autophagy was assessed by Western blotting for detecting microtubule-associated protein light chain 3(LC3). Results CVB3 infection induced ER stress, and ER stress sensors PERK/eIF2α, IRE1/XBP1, and ATF6 were activated. CVB3 infection increased the accumulation of green fluorescent protein(GFP)-LC3 punctuation and induced the conversion from LC3-Ⅰ to phosphatidylethanolamine-conjugated LC3-1(LC3-Ⅱ). CVB3 infection still decreased the expression of mammalian target of rapamycin(mTOR) and p-mTOR. Inhibition of PERK, IRE1, or ATF6 significantly decreased the ratio of LC3-Ⅱ to LC3-Ⅰ in CVB3-infected HeLa cells. Conclusion CVB3 infection induced autophagy through ER stress in HeL a cells, and PERK, IRE1, and ATF6 a pathways participated in the regulation of autophagy. Our data suggested that ER stress may inhibit mTOR signaling pathway to induce autophagy during CVB3 infection.
基金supported by the Mega-projects of Science Research for the 11th Five-Year Plan(No.2009ZX09103-315)the 12th Five-Year Plan(No.2013ZX09301-303-003)+2 种基金the 111 Project(No.111-2-07),the 2011’Program for Excellent ScientificTechnological Innovation Team of Jiangsu Higher Education and the Specific Fund for Public Interest Research of Traditional Chinese Medicine,Ministry of Finance(No.200707008)the National Natural Science Foundation of China(No.81172955)
文摘Abrus mollis is a widely used traditional Chinese medicine for treating acute and chronic hepatitis, steatosis, and fibrosis. It was found that the total flavonoid C-glycosides from Abrus mollis extract(AME) showed potent antioxidant, anti-inflammatory, and hepatoprotective activities. To further investigate the hepatoprotective effect of AME and its possible mechanisms, lipopolysaccharide(LPS)-induced liver injury models were applied in the current study. The results indicated that AME significantly attenuated LPS-induced lipid accumulation in mouse primary hepatocytes as measured by triglyceride(TG) and total cholesterol(TC) assays and Oil Red O staining. Meanwhile, AME exerted a protective effect on LPS-induced liver injury as shown by decreased liver index, serum aminotransferase levels, and hepatic lipid accumulation. Real-time PCR and immunoblot data suggested that AME reversed the LPS-mediated lipid metabolism gene expression, such as sterol regulatory element-binding protein-1(SREBP-1), fatty acid synthase(FAS), and acetyl-CoA carboxylase 1(ACC1). In addition, LPS-induced overexpression of activating transcription factor 4(ATF4), X-box-binding protein-1(XBP-1), and C/EBP homologous protein(CHOP) were dramatically reversed by AME. Furthermore, AME also decreased the expression of LPS-enhanced interleukin-6(IL-6) and cyclooxygenase-2(COX-2). Here, it is demonstrated for the first time that AME ameliorated LPS-induced hepatic lipid accumulation and that this effect of AME can be attributed to its modulation of hepatic de novo fatty acid synthesis. This study also suggested that the hepatoprotective effect of AME may be related to its down-regulation of unfolded protein response(UPR) activation.
基金Projects associated with protein homeostasis in the Liu Lab are financially supported by grants from the National Natural Science Foundation of China(31625004,31872653,and 31800210)the Zhejiang Provincial Talent Program(2019R52005)the 111 Project(B14027).
文摘The endoplasmic reticulum,chloroplasts,and mitochondria are major plant organelles for protein synthesis,photosynthesis,metabolism,and energy production.Protein homeostasis in these organelles,maintained by a balance between protein synthesis and degradation,is essential for cell functions during plant growth,development,and stress resistance.Nucleus-encoded chloroplast-and mitochondrion-targeted proteins and ER-resident proteins are imported from the cytosol and undergo modification and maturation within their respective organelles.Protein folding is an error-prone process that is influenced by both developmental signals and environmental cues;a number of mechanisms have evolved to ensure efficient import and proper folding and maturation of proteins in plant organelles.Misfolded or damaged proteins with nonnative conformations are subject to degradation via complementary or competing pathways:intraorganelle proteases,the organelle-associated ubiquitin-proteasome system,and the selective autophagy of partial or entire organelles.When proteins in nonnative conformations accumulate,the organellespecific unfolded protein response operates to restore protein homeostasis by reducing protein folding demand,increasing protein folding capacity,and enhancing components involved in proteasome-associated protein degradation and autophagy.This review summarizes recent progress on the understanding of protein quality control in the ER,chloroplasts,and mitochondria in plants,with a focus on common mechanisms shared by these organelles during protein homeostasis.
基金This work was supported by grants from the National Natural Science Foundation of China （No. 91232709, No. 811171216, and No. 81161120496 for Prof. Xiao-Chun Chen, and No. 81200991 for Prof. Xiao-Dong Pan） and the National and Fujian Province＇s Key Clinical Specialty Discipline Construction Programs.
文摘Background： Amyloid β （Aβ） deposits and the endoplasmic reticulum stress （ERS） are both well established in the development and progression of Alzheimer＇s disease （AD）. However, the mechanism and role of Aβ-induced ERS in AD-associated pathological progression remain to be elucidated. Methods： The five familial AD （5×FAD） mice and wild-type （WT） mice aged 2, 7, and 12 months were used in the present study. Monis water maze test was used to evaluate their cognitive performance, lmmunofluorescence and Western blot analyses were used to examine the dynamic changes of pro-apoptotic （CCAAT/enhancer-binding protein homologous protein [CHOP] and cleaved caspase-12） and anti-apoptotic factors （chaperone glucose-regulated protein [GRP] 78 and endoplasmic reticulum-associated protein degradation-associated ubiquitin ligase synovial apoptosis inhibitor 1 [SYVN 1]） in the ERS-associated unfolded protein response （UPR） pathway. Results： Compared with age-matched WT mice, 5 xFAD mice showed higher cleaved caspase-3, lower neuron-positive staining at the age of 12 months, but earlier cognitive deficit at the age of 7 months （all P 〈 0.05）. Interestingly, for 2-month-old 5×FAD mice, the related proteins involved in the ERS-associated UPR pathway, including CHOP, cleaved caspase-12, GRP 78, and SYVN 1, were significantly increased when compared with those in age-matched WT mice （all P 〈 0.05）. Moreover, ERS occurred mainly in neurons, not in astrocytes. Conclusions： These findings suggest that compared with those of age-matched WT mice, ERS-associated pro-apoptotic and anti-apoptotic proteins are upregulated in 2-month-old 5×FAD mice, consistent with intracellular Aβ aggregation in neurons.
