bims-unfpre 2024-03-03 papers

bims-unfpre

Biomed News

on Unfolded protein response

Issue of 2024–03–03
ten papers selected by
Susan Logue, University of Manitoba

Targeting the IRE1α-XBP1s axis confers selective vulnerability in hepatocellular carcinoma with activated Wnt signaling.
Multi-omics Resources for Understanding Gene Regulation in Response to ER Stress in Plants.
Collective cell migration relies on PPP1R15-mediated regulation of the endoplasmic reticulum stress response.
SEPN1-related myopathy depends on the oxidoreductase ERO1A and is druggable with the chemical chaperone TUDCA.
Monocyte NLRP3 inflammasome and interleukin-1β activation modulated by alpha-1 antitrypsin therapy in deficient individuals.
ATF6 protects against protein misfolding during cardiac hypertrophy.
The gut microbe-derived metabolite trimethylamine-N-oxide induces aortic valve fibrosis via PERK/ATF-4 and IRE-1α/XBP-1s signaling in vitro and in vivo.
ATF4-dependent increase in mitochondrial-endoplasmic reticulum tethering following OPA1 deletion in skeletal muscle.
Influenza A virus propagation requires the activation of the unfolded protein response and the accumulation of insoluble protein aggregates.
ER remodelling by ER-phagy in neurogenesis.

Oncogene. 2024 Feb 28.

Targeting the IRE1α-XBP1s axis confers selective vulnerability in hepatocellular carcinoma with activated Wnt signaling.

Tingting Zhang, Faming Zhao, Yi Zhang, Ji-Hua Shi, Fengzhen Cui, Weixiang Ma, Kai Wang, Chuanrui Xu, Qingping Zeng, Rong Zhong, Ningning Li, Yong Liu, Yang Jin, Xia Sheng.

Liver-specific Ern1 knockout impairs tumor progression in mouse models of hepatocellular carcinoma (HCC). However, the mechanistic role of IRE1α in human HCC remains unclear. In this study, we show that XBP1s, the major downstream effector of IRE1α, is required for HCC cell survival both in vitro and in vivo. Mechanistically, XBP1s transactivates LEF1, a key co-factor of β-catenin, by binding to its promoter. Moreover, XBP1s physically interacts with LEF1, forming a transcriptional complex that enhances classical Wnt signaling. Consistently, the activities of XBP1s and LEF1 are strongly correlated in human HCC and with disease prognosis. Notably, selective inhibition of XBP1 splicing using an IRE1α inhibitor significantly repressed the viability of tumor explants as well as the growth of tumor xenografts derived from patients with distinct Wnt/LEF1 activities. Finally, machine learning algorithms developed a powerful prognostic signature based on the activities of XBP1s/LEF1. In summary, our study uncovers a key mechanistic role for the IRE1α-XBP1s pathway in human HCC. Targeting this axis could provide a promising therapeutic strategy for HCC with hyperactivated Wnt/LEF1 signaling.

DOI: https://doi.org/10.1038/s41388-024-02988-4
Methods Mol Biol. 2024 ;2772 261-272

Multi-omics Resources for Understanding Gene Regulation in Response to ER Stress in Plants.

Dae Kwan Ko, Federica Brandizzi.

  Proteotoxic stress of the endoplasmic reticulum (ER) is a potentially lethal condition that ensues when the biosynthetic capacity of the ER is overwhelmed. A sophisticated and largely conserved signaling, known as the unfolded protein response (UPR), is designed to monitor and alleviate ER stress. In plants, the emerging picture of gene regulation by the UPR now appears to be more complex than ever before, requiring multi-omics-enabled network-level approaches to be untangled. In the past decade, with an increasing access and decreasing costs of next-generation sequencing (NGS) and high-throughput protein-DNA interaction (PDI) screening technologies, multitudes of global molecular measurements, known as omics, have been generated and analyzed by the research community to investigate the complex gene regulation of plant UPR. In this chapter, we present a comprehensive catalog of omics resources at different molecular levels (transcriptomes, protein-DNA interactomes, and networks) along with the introduction of key concepts in experimental and computational tools in data generation and analyses. This chapter will serve as a starting point for both experimentalists and bioinformaticians to explore diverse omics datasets for their biological questions in the plant UPR, with likely applications also in other species for conserved mechanisms.

Keywords:  Gene regulation; Multi-omics; Networks; Systems biology; The unfolded protein response; Transcription

DOI:  https://doi.org/10.1007/978-1-0716-3710-4_19
Curr Biol. 2024 Feb 27. pii: S0960-9822(24)00156-8. [Epub ahead of print]

Collective cell migration relies on PPP1R15-mediated regulation of the endoplasmic reticulum stress response.

Yujun Chen, Jocelyn A McDonald.

  Collective cell migration is integral to many developmental and disease processes. Previously, we discovered that protein phosphatase 1 (Pp1) promotes border cell collective migration in the Drosophila ovary. We now report that the Pp1 phosphatase regulatory subunit dPPP1R15 is a critical regulator of border cell migration. dPPP1R15 is an ortholog of mammalian PPP1R15 proteins that attenuate the endoplasmic reticulum (ER) stress response. We show that, in collectively migrating border cells, dPPP1R15 phosphatase restrains an active physiological protein kinase R-like ER kinase- (PERK)-eIF2α-activating transcription factor 4 (ATF4) stress pathway. RNAi knockdown of dPPP1R15 blocks border cell delamination from the epithelium and subsequent migration, increases eIF2α phosphorylation, reduces translation, and drives expression of the stress response transcription factor ATF4. We observe similar defects upon overexpression of ATF4 or the eIF2α kinase PERK. Furthermore, we show that normal border cells express markers of the PERK-dependent ER stress response and require PERK and ATF4 for efficient migration. In many other cell types, unresolved ER stress induces initiation of apoptosis. In contrast, border cells with chronic RNAi knockdown of dPPP1R15 survive. Together, our results demonstrate that the PERK-eIF2α-ATF4 pathway, regulated by dPPP1R15 activity, counteracts the physiological ER stress that occurs during collective border cell migration. We propose that in vivo collective cell migration is intrinsically "stressful," requiring tight homeostatic control of the ER stress response for collective cell cohesion, dynamics, and movement.

Keywords:  cell migration; cell protrusions; development; integrated stress response; oogenesis

DOI:  https://doi.org/10.1016/j.cub.2024.02.014
Cell Rep Med. 2024 Feb 19. pii: S2666-3791(24)00062-4. [Epub ahead of print] 101439

SEPN1-related myopathy depends on the oxidoreductase ERO1A and is druggable with the chemical chaperone TUDCA.

Serena Germani, Andrew Tri Van Ho, Alessandro Cherubini, Ersilia Varone, Alexander Chernorudskiy, Giorgia Maria Renna, Stefano Fumagalli, Marco Gobbi, Jacopo Lucchetti, Marco Bolis, Luca Guarrera, Ilaria Craparotta, Giorgia Rastelli, Giorgia Piccoli, Cosimo de Napoli, Leonardo Nogara, Elena Poggio, Marisa Brini, Angela Cattaneo, Angela Bachi, Thomas Simmen, Tito Calì, Susana Quijano-Roy, Simona Boncompagni, Bert Blaauw, Ana Ferreiro, Ester Zito.

  Selenoprotein N (SEPN1) is a protein of the endoplasmic reticulum (ER) whose inherited defects originate SEPN1-related myopathy (SEPN1-RM). Here, we identify an interaction between SEPN1 and the ER-stress-induced oxidoreductase ERO1A. SEPN1 and ERO1A, both enriched in mitochondria-associated membranes (MAMs), are involved in the redox regulation of proteins. ERO1A depletion in SEPN1 knockout cells restores ER redox, re-equilibrates short-range MAMs, and rescues mitochondrial bioenergetics. ERO1A knockout in a mouse background of SEPN1 loss blunts ER stress and improves multiple MAM functions, including Ca2+ levels and bioenergetics, thus reversing diaphragmatic weakness. The treatment of SEPN1 knockout mice with the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) mirrors the results of ERO1A loss. Importantly, muscle biopsies from patients with SEPN1-RM exhibit ERO1A overexpression, and TUDCA-treated SEPN1-RM patient-derived primary myoblasts show improvement in bioenergetics. These findings point to ERO1A as a biomarker and a viable target for intervention and to TUDCA as a pharmacological treatment for SEPN1-RM.

Keywords:  ER stress; ERO1; SEPN1; TUDCA; core myopathy; multi mini-core disease

DOI:  https://doi.org/10.1016/j.xcrm.2024.101439
Thorax. 2024 Feb 28. pii: thorax-2023-221071. [Epub ahead of print]

Monocyte NLRP3 inflammasome and interleukin-1β activation modulated by alpha-1 antitrypsin therapy in deficient individuals.

Debananda Gogoi, Howard Yu, Michelle Casey, Rory Baird, Azeez Yusuf, Luke Forde, Michael E O' Brien, Jesse R West, Tammy Flagg, Noel G McElvaney, Edward Eden, Christian Mueller, Mark L Brantly, Patrick Geraghty, Emer P Reeves.

   INTRODUCTION: Altered complement component 3 (C3) activation in patients with alpha-1 antitrypsin (AAT) deficiency (AATD) has been reported. To understand the potential impact on course of inflammation, the aim of this study was to investigate whether C3d, a cleavage-product of C3, triggers interleukin (IL)-1β secretion via activation of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome. The objective was to explore the effect of AAT augmentation therapy in patients with AATD on the C3d/complement receptor 3 (CR3) signalling axis of monocytes and on circulating pro-inflammatory markers.
METHODS: Inflammatory mediators were detected in blood from patients with AATD (n=28) and patients with AATD receiving augmentation therapy (n=19). Inflammasome activation and IL-1β secretion were measured in monocytes of patients with AATD, and following C3d stimulation in the presence or absence of CR3 or NLRP3 inhibitors.
RESULTS: C3d acting via CR3 induces NLRP3 and pro-IL-1β production, and through induction of endoplasmic reticulum (ER) stress and calcium flux, triggers caspase-1 activation and IL-1β secretion. Treatment of individuals with AATD with AAT therapy results in decreased plasma levels of C3d (3.0±1.2 µg/mL vs 1.3±0.5 µg/mL respectively, p<0.0001) and IL-1β (115.4±30 pg/mL vs 73.3±20 pg/mL, respectively, p<0.0001), with a 2.0-fold decrease in monocyte NLRP3 protein expression (p=0.0303), despite continued ER stress activation.
DISCUSSION: These results provide strong insight into the mechanism of complement-driven inflammation associated with AATD. Although the described variance in C3d and NLRP3 activation decreased post AAT augmentation therapy, results demonstrate persistent C3d and monocyte ER stress, with implications for new therapeutics and clinical practice.

Keywords:  alpha1 antitrypsin deficiency; innate immunity; rare lung diseases

DOI:  https://doi.org/10.1136/thorax-2023-221071
J Mol Cell Cardiol. 2024 Feb 23. pii: S0022-2828(24)00018-X. [Epub ahead of print]189 12-24

ATF6 protects against protein misfolding during cardiac hypertrophy.

Christoph Hofmann, Marjan Aghajani, Cecily D Alcock, Erik A Blackwood, Clara Sandmann, Nicole Herzog, Julia Groß, Lars Plate, R Luke Wiseman, Randal J Kaufman, Hugo A Katus, Tobias Jakobi, Mirko Völkers, Christopher C Glembotski, Shirin Doroudgar.

  Cardiomyocytes activate the unfolded protein response (UPR) transcription factor ATF6 during pressure overload-induced hypertrophic growth. The UPR is thought to increase ER protein folding capacity and maintain proteostasis. ATF6 deficiency during pressure overload leads to heart failure, suggesting that ATF6 protects against myocardial dysfunction by preventing protein misfolding. However, conclusive evidence that ATF6 prevents toxic protein misfolding during cardiac hypertrophy is still pending. Here, we found that activation of the UPR, including ATF6, is a common response to pathological cardiac hypertrophy in mice. ATF6 KO mice failed to induce sufficient levels of UPR target genes in response to chronic isoproterenol infusion or transverse aortic constriction (TAC), resulting in impaired cardiac growth. To investigate the effects of ATF6 on protein folding, the accumulation of poly-ubiquitinated proteins as well as soluble amyloid oligomers were directly quantified in hypertrophied hearts of WT and ATF6 KO mice. Whereas only low levels of protein misfolding was observed in WT hearts after TAC, ATF6 KO mice accumulated increased quantities of misfolded protein, which was associated with impaired myocardial function. Collectively, the data suggest that ATF6 plays a critical adaptive role during cardiac hypertrophy by protecting against protein misfolding.

Keywords:  ATF6; Cardiac hypertrophy; Protein misfolding; Proteostasis; UPR; Unfolded protein response

DOI:  https://doi.org/10.1016/j.yjmcc.2024.02.001
Atherosclerosis. 2023 Dec 27. pii: S0021-9150(23)05352-2. [Epub ahead of print]391 117431

The gut microbe-derived metabolite trimethylamine-N-oxide induces aortic valve fibrosis via PERK/ATF-4 and IRE-1α/XBP-1s signaling in vitro and in vivo.

Zhenyu Xiong, Jiaying Li, Rihua Huang, Huimin Zhou, Xingfeng Xu, Shaozhao Zhang, Peihan Xie, Miaohong Li, Yue Guo, Xinxue Liao, Xiaodong Zhuang.

   BACKGROUND AND AIMS: The gut microbe-derived metabolite trimethylamine-N-oxide (TMAO) has been implicated in the development of cardiovascular fibrosis. Endoplasmic reticulum (ER) stress occurs after the dysfunction of ER and its structure. The three signals PERK/ATF-4, IRE-1α/XBP-1s and ATF6 are activated upon ER stress. Recent reports have suggested that the activation of PERK/ATF-4 and IRE-1α/XBP-1s signaling contributes to cardiovascular fibrosis. However, whether TMAO mediates aortic valve fibrosis by activating PERK/ATF-4 and IRE-1α/XBP-1s signaling remains unclear.
METHODS: Human aortic valve interstitial cells (AVICs) were isolated from aortic valve leaflets. PERK IRE-1α, ATF-4, XBP-1s and CHOP expression, and production of collagen Ⅰ and TGF-β1 were analyzed following treatment with TMAO. The role of PERK/ATF-4 and IRE-1α/XBP-1s signaling pathways in TMAO-induced fibrotic formation was determined using inhibitors and small interfering RNA.
RESULTS: Diseased valves produced greater levels of ATF-4, XBP-1, collagen Ⅰ and TGF-β1. Interestingly, diseased cells exhibited augmented PERK/ATF-4 and IRE-1α/XBP-1s activation after TMAO stimulation. Inhibition and silencing of PERK/ATF-4 and IRE-1α/XBP-1s each resulted in enhanced suppression of TMAO-induced fibrogenic activity in diseased cells. Mice treated with dietary choline supplementation had substantially increased TMAO levels and aortic valve fibrosis, which were reduced by 3,3-dimethyl-1-butanol (DMB, an inhibitor of trimethylamine formation) treatment. Moreover, a high-choline and high-fat diet remodeled the gut microbiota in mice.
CONCLUSIONS: TMAO promoted aortic valve fibrosis through activation of PERK/ATF-4 and IRE-1α/XBP-1s signaling pathways in vitro and in vivo. Modulation of diet, gut microbiota, TMAO, PERK/ATF-4 and IRE1-α/XBP-1s may be a promising approach to prevent aortic valve fibrosis.

Keywords:  ATF-4; Aortic valve fibrosis; Gut microbiota; TMAO; XBP-1s

DOI:  https://doi.org/10.1016/j.atherosclerosis.2023.117431
J Cell Physiol. 2024 Feb 28.

ATF4-dependent increase in mitochondrial-endoplasmic reticulum tethering following OPA1 deletion in skeletal muscle.

Antentor Hinton, Prasanna Katti, Margaret Mungai, Duane D Hall, Olha Koval, Jianqiang Shao, Zer Vue, Edgar Garza Lopez, Rahmati Rostami, Kit Neikirk, Jessica Ponce, Jennifer Streeter, Brandon Schickling, Serif Bacevac, Chad Grueter, Andrea Marshall, Heather K Beasley, Young Do Koo, Sue C Bodine, Nayeli G Reyes Nava, Anita M Quintana, Long-Sheng Song, Isabella M Grumbach, Renata O Pereira, Brian Glancy, E Dale Abel.

  Mitochondria and endoplasmic reticulum (ER) contact sites (MERCs) are protein- and lipid-enriched hubs that mediate interorganellar communication by contributing to the dynamic transfer of Ca2+ , lipid, and other metabolites between these organelles. Defective MERCs are associated with cellular oxidative stress, neurodegenerative disease, and cardiac and skeletal muscle pathology via mechanisms that are poorly understood. We previously demonstrated that skeletal muscle-specific knockdown (KD) of the mitochondrial fusion mediator optic atrophy 1 (OPA1) induced ER stress and correlated with an induction of Mitofusin-2, a known MERC protein. In the present study, we tested the hypothesis that Opa1 downregulation in skeletal muscle cells alters MERC formation by evaluating multiple myocyte systems, including from mice and Drosophila, and in primary myotubes. Our results revealed that OPA1 deficiency induced tighter and more frequent MERCs in concert with a greater abundance of MERC proteins involved in calcium exchange. Additionally, loss of OPA1 increased the expression of activating transcription factor 4 (ATF4), an integrated stress response (ISR) pathway effector. Reducing Atf4 expression prevented the OPA1-loss-induced tightening of MERC structures. OPA1 reduction was associated with decreased mitochondrial and sarcoplasmic reticulum, a specialized form of ER, calcium, which was reversed following ATF4 repression. These data suggest that mitochondrial stress, induced by OPA1 deficiency, regulates skeletal muscle MERC formation in an ATF4-dependent manner.

Keywords:  activating transcription factor 4; endoplasmic reticulum; integrated stress response; interorganelle communication; mitochondria

DOI:  https://doi.org/10.1002/jcp.31204
iScience. 2024 Mar 15. 27(3): 109100

Influenza A virus propagation requires the activation of the unfolded protein response and the accumulation of insoluble protein aggregates.

Mariana Marques, Bruno Ramos, Hélio Albuquerque, Marisa Pereira, Diana Roberta Ribeiro, Alexandre Nunes, Jéssica Sarabando, Daniela Brás, Ana Rita Ferreira, Rui Vitorino, Maria João Amorim, Artur M S Silva, Ana Raquel Soares, Daniela Ribeiro.

  Influenza A virus (IAV) employs multiple strategies to manipulate cellular mechanisms and support proper virion formation and propagation. In this study, we performed a detailed analysis of the interplay between IAV and the host cells' proteostasis throughout the entire infectious cycle. We reveal that IAV infection activates the inositol requiring enzyme 1 (IRE1) branch of the unfolded protein response, and that this activation is important for an efficient infection. We further observed the accumulation of virus-induced insoluble protein aggregates, containing both viral and host proteins, associated with a dysregulation of the host cell RNA metabolism. Our data indicate that this accumulation is important for IAV propagation and favors the final steps of the infection cycle, more specifically the virion assembly. These findings reveal additional mechanisms by which IAV disrupts host proteostasis and uncovers new cellular targets that can be explored for the development of host-directed antiviral strategies.

Keywords:  Virology

DOI:  https://doi.org/10.1016/j.isci.2024.109100
Nat Cell Biol. 2024 Mar 01.

ER remodelling by ER-phagy in neurogenesis.

Maurizio Molinari.

DOI: https://doi.org/10.1038/s41556-024-01362-6