bims-unfpre Biomed News
on Unfolded protein response
Issue of 2023‒04‒30
nine papers selected by
Susan Logue
University of Manitoba
  1. Deletion of the Unfolded Protein Response Transducer IRE1α Is Detrimental to Aging Photoreceptors and to ER Stress-Mediated Retinal Degeneration.
  2. Metal-Binding Proteins Cross-Linking with Endoplasmic Reticulum Stress in Cardiovascular Diseases.
  3. Deubiquitylase OTUD3 Mediates Endoplasmic Reticulum Stress through Regulating Fortilin Stability to Restrain Dopaminergic Neurons Apoptosis.
  4. Ursodeoxycholic Acid Binds PERK and Ameliorates Neurite Atrophy in a Cellular Model of GM2 Gangliosidosis.
  5. Hepatitis Delta Virus Antigens Trigger Oxidative Stress, Activate Antioxidant Nrf2/ARE Pathway, and Induce Unfolded Protein Response.
  6. ER stress modulates the immune regulatory ability in gut M2 cells of patients with ulcerative colitis.
  7. RNA Sequencing in Hypoxia-Adapted T98G Glioblastoma Cells Provides Supportive Evidence for IRE1 as a Potential Therapeutic Target.
  8. Secretome Screening of BRAFV600E-Mutated Colon Cancer Cells Resistant to Vemurafenib.
  9. ATF5 regulates tubulointerstitial injury in diabetic kidney disease via mitochondrial unfolded protein response.
  1. Invest Ophthalmol Vis Sci. 2023 Apr 03. 64(4): 30
    Deletion of the Unfolded Protein Response Transducer IRE1α Is Detrimental to Aging Photoreceptors and to ER Stress-Mediated Retinal Degeneration.
    Dawiyat Massoudi, Seán Gorman, Yien-Ming Kuo, Takao Iwawaki, Scott A Oakes, Feroz R Papa, Douglas B Gould.
      Purpose: The unfolded protein response (UPR) is triggered when the protein folding capacity of the endoplasmic reticulum (ER) is overwhelmed and misfolded proteins accumulate in the ER, a condition referred to as ER stress. IRE1α is an ER-resident protein that plays major roles in orchestrating the UPR. Several lines of evidence implicate the UPR and its transducers in neurodegenerative diseases, including retinitis pigmentosa (RP), a group of inherited diseases that cause progressive dysfunction and loss of rod and cone photoreceptors. This study evaluated the contribution of IRE1α to photoreceptor development, homeostasis, and degeneration.Methods: We used a conditional gene targeting strategy to selectively inactivate Ire1α in mouse rod photoreceptors. We used a combination of optical coherence tomography (OCT) imaging, histology, and electroretinography (ERG) to assess longitudinally the effect of IRE1α deficiency in retinal development and function. Furthermore, we evaluated the IRE1α-deficient retina responses to tunicamycin-induced ER stress and in the context of RP caused by the rhodopsin mutation RhoP23H.
    Results: OCT imaging, histology, and ERG analyses did not reveal abnormalities in IRE1α-deficient retinas up to 3 months old. However, by 6 months of age, the Ire1α mutant animals showed reduced outer nuclear layer thickness and deficits in retinal function. Furthermore, conditional inactivation of Ire1α in rod photoreceptors accelerated retinal degeneration caused by the RhoP23H mutation.
    Conclusions: These data suggest that IRE1α is dispensable for photoreceptor development but important for photoreceptor homeostasis in aging retinas and for protecting against ER stress-mediated photoreceptor degeneration.
    DOI:  https://doi.org/10.1167/iovs.64.4.30
  2. J Cardiovasc Dev Dis. 2023 Apr 17. pii: 171. [Epub ahead of print]10(4):
    Metal-Binding Proteins Cross-Linking with Endoplasmic Reticulum Stress in Cardiovascular Diseases.
    Kejuan Li, Yongnan Li, Hong Ding, Jianshu Chen, Xiaowei Zhang.
      The endoplasmic reticulum (ER), an essential organelle in eukaryotic cells, is widely distributed in myocardial cells. The ER is where secreted protein synthesis, folding, post-translational modification, and transport are all carried out. It is also where calcium homeostasis, lipid synthesis, and other processes that are crucial for normal biological cell functioning are regulated. We are concerned that ER stress (ERS) is widespread in various damaged cells. To protect cells' function, ERS reduces the accumulation of misfolded proteins by activating the unfolded protein response (UPR) pathway in response to numerous stimulating factors, such as ischemia or hypoxia, metabolic disorders, and inflammation. If these stimulatory factors are not eliminated for a long time, resulting in the persistence of the UPR, it will aggravate cell damage through a series of mechanisms. In the cardiovascular system, it will cause related cardiovascular diseases and seriously endanger human health. Furthermore, there has been a growing number of studies on the antioxidative stress role of metal-binding proteins. We observed that a variety of metal-binding proteins can inhibit ERS and, hence, mitigate myocardial damage.
    Keywords:  Ca2+; UPR; cardiovascular disease; endoplasmic reticulum stress; metal-binding protein
    DOI:  https://doi.org/10.3390/jcdd10040171
  3. Antioxidants (Basel). 2023 Mar 26. pii: 809. [Epub ahead of print]12(4):
    Deubiquitylase OTUD3 Mediates Endoplasmic Reticulum Stress through Regulating Fortilin Stability to Restrain Dopaminergic Neurons Apoptosis.
    Ling Chen, Xuejie Huan, Fengju Jia, Zhen Zhang, Mingxia Bi, Lin Fu, Xixun Du, Xi Chen, Chunling Yan, Qian Jiao, Hong Jiang.
      OTU domain-containing protein 3 (OTUD3) knockout mice exhibited loss of nigral dopaminergic neurons and Parkinsonian symptoms. However, the underlying mechanisms are largely unknown. In this study, we observed that the inositol-requiring enzyme 1α (IRE1α)-induced endoplasmic reticulum (ER) stress was involved in this process. We found that the ER thickness and the expression of protein disulphide isomerase (PDI) were increased, and the apoptosis level was elevated in the dopaminergic neurons of OTUD3 knockout mice. These phenomena were ameliorated by ER stress inhibitor tauroursodeoxycholic acid (TUDCA) treatment. The ratio of p-IRE1α/IRE1α, and the expression of X-box binding protein 1-spliced (XBP1s) were remarkably increased after OTUD3 knockdown, which was inhibited by IRE1α inhibitor STF-083010 treatment. Moreover, OTUD3 regulated the ubiquitination level of Fortilin through binding with the OTU domain. OTUD3 knockdown resulted in a decrease in the interaction ability of IRE1α with Fortilin and finally enhanced the activity of IRE1α. Taken together, we revealed that OTUD3 knockout-induced injury of dopaminergic neurons might be caused by activating IRE1α signaling in ER stress. These findings demonstrated that OTUD3 played a critical role in dopaminergic neuron neurodegeneration, which provided new evidence for the multiple and tissue-dependent functions of OTUD3.
    Keywords:  ER stress; Fortilin; IRE1α; OTUD3; XBP1s
    DOI:  https://doi.org/10.3390/antiox12040809
  4. Int J Mol Sci. 2023 Apr 13. pii: 7209. [Epub ahead of print]24(8):
    Ursodeoxycholic Acid Binds PERK and Ameliorates Neurite Atrophy in a Cellular Model of GM2 Gangliosidosis.
    Carolina Morales, Macarena Fernandez, Rodrigo Ferrer, Daniel Raimunda, Dolores C Carrer, Mariana Bollo.
      The Unfolded protein response (UPR), triggered by stress in the endoplasmic reticulum (ER), is a key driver of neurodegenerative diseases. GM2 gangliosidosis, which includes Tay-Sachs and Sandhoff disease, is caused by an accumulation of GM2, mainly in the brain, that leads to progressive neurodegeneration. Previously, we demonstrated in a cellular model of GM2 gangliosidosis that PERK, a UPR sensor, contributes to neuronal death. There is currently no approved treatment for these disorders. Chemical chaperones, such as ursodeoxycholic acid (UDCA), have been found to alleviate ER stress in cell and animal models. UDCA's ability to move across the blood-brain barrier makes it interesting as a therapeutic tool. Here, we found that UDCA significantly diminished the neurite atrophy induced by GM2 accumulation in primary neuron cultures. It also decreased the up-regulation of pro-apoptotic CHOP, a downstream PERK-signaling component. To explore its potential mechanisms of action, in vitro kinase assays and crosslinking experiments were performed with different variants of recombinant protein PERK, either in solution or in reconstituted liposomes. The results suggest a direct interaction between UDCA and the cytosolic domain of PERK, which promotes kinase phosphorylation and dimerization.
    Keywords:  ATP binding pocket; chemical chaperones; lysosomal storage disease
    DOI:  https://doi.org/10.3390/ijms24087209
  5. Antioxidants (Basel). 2023 Apr 21. pii: 974. [Epub ahead of print]12(4):
    Hepatitis Delta Virus Antigens Trigger Oxidative Stress, Activate Antioxidant Nrf2/ARE Pathway, and Induce Unfolded Protein Response.
    Olga A Smirnova, Olga N Ivanova, Furkat Mukhtarov, Vladimir T Valuev-Elliston, Artemy P Fedulov, Petr M Rubtsov, Natalia F Zakirova, Sergey N Kochetkov, Birke Bartosch, Alexander V Ivanov.
      Hepatitis delta virus (HDV) is a viroid-like satellite that may co-infect individuals together with hepatitis B virus (HBV), as well as cause superinfection by infecting patients with chronic hepatitis B (CHB). Being a defective virus, HDV requires HBV structural proteins for virion production. Although the virus encodes just two forms of its single antigen, it enhances the progression of liver disease to cirrhosis in CHB patients and increases the incidence of hepatocellular carcinoma. HDV pathogenesis so far has been attributed to virus-induced humoral and cellular immune responses, while other factors have been neglected. Here, we evaluated the impact of the virus on the redox status of hepatocytes, as oxidative stress is believed to contribute to the pathogenesis of various viruses, including HBV and hepatitis C virus (HCV). We show that the overexpression of large HDV antigen (L-HDAg) or autonomous replication of the viral genome in cells leads to increased production of reactive oxygen species (ROS). It also leads to the upregulated expression of NADPH oxidases 1 and 4, cytochrome P450 2E1, and ER oxidoreductin 1α, which have previously been shown to mediate oxidative stress induced by HCV. Both HDV antigens also activated the Nrf2/ARE pathway, which controls the expression of a spectrum of antioxidant enzymes. Finally, HDV and its large antigen also induced endoplasmic reticulum (ER) stress and the concomitant unfolded protein response (UPR). In conclusion, HDV may enhance oxidative and ER stress induced by HBV, thus aggravating HBV-associated pathologies, including inflammation, liver fibrosis, and the development of cirrhosis and hepatocellular carcinoma.
    Keywords:  NADPH oxidase; Nrf2; hepatitis delta virus; oxidative stress; unfolded protein response
    DOI:  https://doi.org/10.3390/antiox12040974
  6. iScience. 2023 Apr 21. 26(4): 106498
    ER stress modulates the immune regulatory ability in gut M2 cells of patients with ulcerative colitis.
    Baisui Feng, Lingzhi Xu, Shuo Song, Huazhen Liu, Yan Li, Suqin Hu, Qing Shu, Jiangqi Liu, Zhiqiang Liu, Haiqiong Yu, Pingchang Yang.
      This study aims to characterize the impaired immune regulatory function of Mφ obtained from UC patient colon lavage fluid (CLF). Mφs were the largest proportion (21.3 4.0%) of the CLF-derived cellular components. Less abundant and weaker immune suppressive function were observed in M2 Mφs (M2 cells) of the ulcerative colitis (UC) group. High levels of endoplasmic reticulum (ER) stress associated molecules were detected in UC M2 cells. The spliced X box binding protein-1 (XBP1) gene was negatively correlated with programmed death ligand-1 (PD-L1) in UC M2 cells. XBP1 promoted the expression of ring-finger protein 20 (Rnf20) in M2 cells. Rnf20 reduced PD-L1 abundance in UC M2 cells and impaired the immune suppressive ability. Inhibition of Rnf20 restored the immune regulating capacity of M2 cells and suppressed experimental colitis.
    Keywords:  Gastroenterology; Immunology; Transcriptomics; immune response
    DOI:  https://doi.org/10.1016/j.isci.2023.106498
  7. Genes (Basel). 2023 Mar 31. pii: 841. [Epub ahead of print]14(4):
    RNA Sequencing in Hypoxia-Adapted T98G Glioblastoma Cells Provides Supportive Evidence for IRE1 as a Potential Therapeutic Target.
    Brian E White, Yichuan Liu, Hakon Hakonarson, Russell J Buono.
      Glioblastoma (GBM) is an aggressive brain cancer with a median survival time of 14.6 months after diagnosis. GBM cells have altered metabolism and exhibit the Warburg effect, preferentially producing lactate under aerobic conditions. After standard-of-care treatment for GBM, there is an almost 100% recurrence rate. Hypoxia-adapted, treatment-resistant GBM stem-like cells are thought to drive this high recurrence rate. We used human T98G GBM cells as a model to identify differential gene expression induced by hypoxia and to search for potential therapeutic targets of hypoxia adapted GBM cells. RNA sequencing (RNAseq) and bioinformatics were used to identify differentially expressed genes (DEGs) and cellular pathways affected by hypoxia. We also examined expression of lactate dehydrogenase (LDH) genes using qRT-PCR and zymography as LDH dysregulation is a feature of many cancers. We found 2630 DEGs significantly altered by hypoxia (p < 0.05), 1241 upregulated in hypoxia and 1389 upregulated in normoxia. Hypoxia DEGs were highest in pathways related to glycolysis, hypoxia response, cell adhesion and notably the endoplasmic reticulum, including the inositol-requiring enzyme 1 (IRE1)-mediated unfolded protein response (UPR). These results, paired with numerous published preclinical data, provide additional evidence that inhibition of the IRE1-mediated UPR may have therapeutic potential in treating GBM. We propose a possible drug repurposing strategy to simultaneously target IRE1 and the spleen tyrosine kinase (SYK) in patients with GBM.
    Keywords:  ERN1; IRE1; LDH; RNA sequencing; SYK; T98G; fostamatinib; glioblastoma; hypoxia
    DOI:  https://doi.org/10.3390/genes14040841
  8. Biology (Basel). 2023 Apr 17. pii: 608. [Epub ahead of print]12(4):
    Secretome Screening of BRAFV600E-Mutated Colon Cancer Cells Resistant to Vemurafenib.
    Iris Car, Antje Dittmann, Marko Klobučar, Petra Grbčić, Sandra Kraljević Pavelić, Mirela Sedić.
      Patients with metastatic colorectal cancer (mCRC) carrying BRAFV600E mutation have worse response to chemotherapy and poor prognosis. The BRAFV600E inhibitor vemurafenib has shown modest efficacy as monotherapy in BRAF-mutated mCRC due to the development of resistance. The aim of this study was to conduct a comparative proteomics profiling of the secretome from vemurafenib-sensitive vs. -resistant colon cancer cells harboring BRAFV600E mutation in order to identify specific secretory features potentially associated with changes in the resistant cells' phenotype. Towards this aim, we employed two complementary proteomics approaches including two-dimensional gel electrophoresis coupled with MALDI-TOF/TOF mass spectrometry and label-free quantitative LC-MS/MS analysis. Obtained results pointed to aberrant regulation of DNA replication and endoplasmic reticulum stress as the major secretome features associated with chemoresistant phenotype. Accordingly, two proteins implicated in these processes including RPA1 and HSPA5/GRP78 were discussed in more details in the context of biological networks and their importance as potential secretome targets for further functional and clinical evaluation. Expression patterns of RPA1 and HSPA5/GRP78 in tumor tissues from colon cancer patients were also found in additional in silico analyses to be associated with BRAFV600E mutation status, which opens the possibility to extrapolate our findings and their clinical implication to other solid tumors harboring BRAFV600E mutation, such as melanoma.
    Keywords:  BRAF inhibition; BRAFV600E; DNA replication; ER stress; HSPA5/GRP78; RPA1; chemoresistance; colon cancer; secretome; vemurafenib
    DOI:  https://doi.org/10.3390/biology12040608
  9. Mol Med. 2023 Apr 24. 29(1): 57
    ATF5 regulates tubulointerstitial injury in diabetic kidney disease via mitochondrial unfolded protein response.
    Yifei Liu, Lei Zhang, Shumin Zhang, Jialu Liu, Xiaohui Li, Kexin Yang, Danyi Yang, Yu Liu, Lin Sun, Fuyou Liu, Li Xiao.
      BACKGROUND: Mitochondrial quality control (MQC) plays a critical role in the progression of tubulointerstitial injury in diabetic kidney disease (DKD). The mitochondrial unfolded protein response (UPRmt), which is an important MQC process, is activated to maintain mitochondrial protein homeostasis in response to mitochondrial stress. Activating transcription factor 5 (ATF5) is critical in the mammalian UPRmt via mitochondria-nuclear translocation. However, the role of ATF5 and UPRmt in tubular injury under DKD conditions is unknown.METHODS: ATF5 and UPRmt-related proteins including heat shock protein 60 (HSP60) and Lon peptidase 1 (LONP1), in DKD patients and db/db mice were examined by immunohistochemistry (IHC) and western blot analysis. Eight-week-old db/db mice were injected with ATF5-shRNA lentiviruses via the tail vein, and a negative lentivirus was used as a control. The mice were euthanized at 12 weeks, and dihydroethidium (DHE) and TdT-mediated dUTP nick end labeling (TUNEL) assays were performed to evaluate reactive oxygen species (ROS) production and apoptosis in kidney sections, respectively. In vitro, ATF5-siRNA, ATF5 overexpression plasmids or HSP60-siRNA were transfected into HK-2 cells to evaluate the effect of ATF5 and HSP60 on tubular injury under ambient hyperglycemic conditions. Mitochondrial superoxide (MitoSOX) staining was used to gauge mitochondrial oxidative stress levels, and the early stage of cell apoptosis was examined by Annexin V-FITC kits.
    RESULTS: Increased ATF5, HSP60 and LONP1 expression was observed in the kidney tissue of DKD patients and db/db mice and was tightly correlated with tubular damage. The inhibition of HSP60 and LONP1, improvements in serum creatinine, tubulointerstitial fibrosis and apoptosis were observed in db/db mice treated with lentiviruses carrying ATF5 shRNA. In vitro, the expression of ATF5 was increased in HK-2 cells exposed to high glucose (HG) in a time-dependent manner, which was accompanied by the overexpression of HSP60, fibronectin (FN) and cleaved-caspase3 (C-CAS3). ATF5-siRNA transfection inhibited the expression of HSP60 and LONP1, which was accompanied by reduced oxidative stress and apoptosis in HK-2 cells exposed to sustained exogenous high glucose. ATF5 overexpression exacerbated these impairments. HSP60-siRNA transfection blocked the effect of ATF5 on HK-2 cells exposed to continuous HG treatment. Interestingly, ATF5 inhibition exacerbated mitochondrial ROS levels and apoptosis in HK-2 cells in the early period of HG intervention (6 h).
    CONCLUSIONS: ATF5 could exert a protective effect in a very early stage but promoted tubulointerstitial injury by regulating HSP60 and the UPRmt pathway under DKD conditions, providing a potential target for the prevention of DKD progression.
    Keywords:  ATF5; Apoptosis; Diabetic kidney disease; Oxidative stress; Tubular cell; UPRmt
    DOI:  https://doi.org/10.1186/s10020-023-00651-4
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