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The accessory protein ORF3a hijacks the CLCC1 chloride channel to disrupt ER homeostasis in betacoronavirus pathogenesis.

Beta-coronavirus infection disrupts endoplasmic reticulum (ER) homeostasis; however, the mechanisms by which viral proteins manipulate ER-resident factors remain unclear. Here, we report that the SARS-CoV-2 accessory protein ORF3a binds to the ER chloride channel CLCC1, thereby impairing ER ion homeostasis, activating the unfolded protein response, and inducing endomembrane remodeling. Using newly developed ratiometric reporters, we showed that this interaction exacerbated the basal levels of ER-phagy and nucleophagy. Importantly, CLCC1 counteracted ORF3a by sequestering it within the ER, atte…

TurboID-Based IRE1 Interactome Reveals Participants of the Endoplasmic Reticulum-Associated Protein Degradation Machinery in the Human Mast Cell Leukemia Cell Line HMC-1.2.

The unfolded protein response is an intricate system of sensor proteins in the endoplasmic reticulum (ER) that recognizes misfolded proteins and transmits information via transcription factors to either regain proteostasis or, depending on the severity, to induce apoptosis. The main transmembrane sensor is IRE1α, which contains cytoplasmic kinase and RNase domains relevant for its activation and the mRNA splicing of the transcription factor XBP1. Mast cell leukemia (MCL) is a severe form of systemic mastocytosis. The inhibition of IRE1α in the MCL cell line HMC-1.2 has anti-proliferative and p…

Dark noise and retinal degeneration from D190N-rhodopsin.

Numerous rhodopsin mutations have been implicated in night blindness and retinal degeneration, often with unclear etiology. D190N-rhodopsin … cause of disease. Instead, the low pigment content, shortened outer-segment length, and a moderate unfolded protein response implicate protein misfolding as the major pathogenic problem. Finally, D190N-Rho also provided some insight into the mechanism of spontaneous pigment excitation.

Expression of Glucose-Regulated Protein 78 and miR-199a in Rat Brain After Fatal Ligature Strangulation.

The roles of endoplasmic reticulum (ER) stress and microRNA in the brain tissue after fatal mechanical asphyxia have not been clearly elucidated. We examined the expression of glucose-regulated protein 78 (GRP78), the key regulator of unfolded protein response, and miR-199a in the brain tissues of rats subjected to fatal ligature strangulation to understand the roles of ER stress and microRNA in ligature strangulation. The expressions of GRP78 and miR-199a in rat cortex, hippocampi, and midbrain were measured by immunohistochemistry and Western blot analysis in a rat model of ligature strangul…

Activation of sphingosine kinase 2 by endoplasmic reticulum stress ameliorates hepatic steatosis and insulin resistance in mice.

UNLABELLED: The endoplasmic reticulum (ER) is the principal organelle in the cell for protein folding and trafficking, lipid synthesis, and cellular calcium homeostasis. Perturbation of ER function results in activation of the unfolded protein response (UPR) and is implicated in abnormal lipid biosynthesis and development of insulin resistance. In this study, we investigated whether transcription of sphingosine kinase (Sphk)2 is regulated by ER stress-mediated UPR pathways. Sphk2, a major isotype of sphingosine kinase in the liver, was transcriptionally up-regulated by tunicamycin and lipopoly…

Роль BP/GRP78, связанного с эндоплазмическим ретикулумом, в стойкой инфекции хламидийной пневмонии, вызванной интерфероном.

Прямое взаимодействие хламидии с эндоплазмической ретикулумой (ER) имеет важное значение для внутриклеточной продуктивной инфекции. Вместе с тем мало что известно о взаимодействии между хламидией и ER в условиях клеточного стресса, которое наблюдается в интерферональной гамма-(IFN-__) вызванной хламидиальной стойкой инфекции. Реагирование ER на стрессы в централизованном порядке регулируется развернутой белковой реакцией (УПО) под контролем сопровождающего ER BiP/GRP78 для поддержания клеточного гомеостаза. В этом исследовании мы могли бы продемонстрировать, что ЧП непосредственно контактирова

Совпадение в аннотации оригинала
Direct interaction of Chlamydiae with the endoplasmic reticulum (ER) is essential in intracellular productive infection. However, little is … (IFN-γ) induced chlamydial persistent infection. ER stress responses are centrally regulated by the unfolded protein response (UPR) under the control of the ER chaperone BiP/GRP78 to maintain cellular homeostasis. In this study, we could show that the ER directly contacted with productive and IFN-γ-induced persistent inclusions of Chlamydia pneumoniae (Cpn). BiP/GRP78 indu …

mTOR activation promotes plasma cell differentiation and bypasses XBP-1 for immunoglobulin secretion.

Plasma cells (PCs) are responsible for the secretion of antibodies. The development of fully functional PCs relies on the activation of the inositol-requiring enzyme 1/X-box binding protein 1 (IRE1/XBP-1) arm of the unfolded protein response (UPR). XBP-1-deficient PCs secrete antibodies poorly and exhibit distensions of the endoplasmic reticulum (ER). The kinase mammalian target of rapamycin (mTOR) promotes anabolic activities and is negatively regulated by the tuberous sclerosis complex (TSC). Deletion of TSC1 renders mTOR hyperactive. To explore the relationship between mTOR and the UPR in P…

Reticulon-4A (Nogo-A) redistributes protein disulfide isomerase to protect mice from SOD1-dependent amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease inherited in a small subset of patients. The SOD1(G93A) transgenic mouse … causes a more homogeneous expression pattern in vivo. These effects occur without induction of the unfolded protein response. To examine the effect of PDI redistribution on ALS disease progression, we conducted survival and behavior studies of SOD1(G93A) mice. Deletion of a single copy of the NogoA,B gene accelerates disease onset and progression, while deletion of both c …

Region-specific microRNA signatures in the human epididymis.

Insulin resistance in obesity and type 2 diabetes (T2D) is characterized by reduced insulin-stimulated glucose uptake, accumulation of triacylglycerol, mitochondrial dysfunction, and altered protein metabolism in skeletal muscle. This may involve disturbed endoplasmic reticulum (ER) homeostasis, leading to alterations in the unfolded protein response (UPR) and, hence, the protein folding capacity. Here, we investigated whether markers of UPR activity are elevated in skeletal muscle in obesity and T2D and to what extent insulin regulates these UPR markers. In a case-control design, we determine…

Efficient deduction of encoded local response within a thermodynamically perturbed folded protein.

Externally imposed perturbations can subtly reshape protein structure and mechanics prior to the emergence of global unfolding signatures. Delineating locally sensitive zones, however, can pose immense challenges. Subjecting a small folded protein to isotropic pressure spanning 0.001-10 kbar, we develop a simplified and interpretable computational framework to characterize local responses embedded within its conformational ensemble. Pairwise mechanical stiffness descriptors are treated as high-dimensional mechanical fingerprints and projected using linear discriminant analysis (LDA) to identif

Engineering stem cell-derived islets for type 1 diabetes: genetic strategies for immune evasion and stress resilience.

Type 1 diabetes (T1D) is characterized by autoimmune-mediated destruction of pancreatic β-cells, resulting in lifelong insulin dependence an … stress-resilience pathways involving renalase (RNLS), thioredoxin-interacting protein (TXNIP), and unfolded protein response regulators. We further highlight how β-cell stress can amplify immune recognition and graft dysfunction. Collectively, these approaches support multifunctional engineered SCIs designed to overcome immune-mediated and intrinsic stress-related barrier …

Pyrazolone-based ERO1 inhibitors in ERO1-driven triple-negative breast cancer and SEPN1-related myopathy: Structure-activity relationship and therapeutic potential.

Endoplasmic reticulum oxidoreductin 1 alpha (ERO1A) is a disulfide oxidase that facilitates oxidative protein folding by reoxidizing protein disulfide isomerase (PDI), a process essential for maintaining endoplasmic reticulum (ER) homeostasis. Under ER stress, ERO1A expression is upregulated via the unfolded protein response (UPR), promoting cell survival. However, sustained ERO1A activity can impair proteostasis and contribute to disease. Notably, ERO1A is overexpressed in triple-negative breast cancer (TNBC), where it supports tumor growth and adaptation to hypoxia, and in SEPN1-related myop…

G-CSF resistance of ELANE-mutant neutropenia depends on SERF1-containing truncated-neutrophil elastase aggregates.

Severe congenital neutropenia (SCN) is frequently associated with dominant point mutations in ELANE, the gene encoding neutrophil elastase ( … runcated alternate NE. Unlike G-CSF-sensitive ELANE mutations that induce endoplasmic reticulum and unfolded protein response stress, we found that the mutation of the ELANE translation initiation codon resulted in NE aggregates and activated proapoptotic aggrephagy, as determined by downregulated BAG1 expression, decreased BAG1/BAG3 ratio, NE colocalization with BAG3, and …

Mechanisms of liver injury in high fat sugar diet fed mice that lack hepatocyte X-box binding protein 1.

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of liver diseases in the United States and can progress to cirrhosis, end-stage liver disease and need for liver transplantation. There are limited therapies for NAFLD, in part, due to incomplete understanding of the disease pathogenesis, which involves different cell populations in the liver. Endoplasmic reticulum stress and its adaptative unfolded protein response (UPR) signaling pathway have been implicated in the progression from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH). We have previously show…

Zinc ions negatively regulate proapoptotic signaling in cells expressing oncogenic mutant Ras.

Mutational activation of the Ras family of proto-oncogenes promotes cell survival and proliferation. Studies using cells cultured in vitro h … n involved in the induction of cell death. Transcriptome analyses suggest that HrasG12V induces the unfolded protein response (UPR). Further analyses of intracellular signaling biomolecules related to the UPR indicate that HrasG12V activates inositol-requiring protein 1 (IRE1), which synergizes with Zn2+ deficiency to activate JNK and p38 MAPK signaling. These results prov …

The P300/XBP1s/Herpud1 axis promotes macrophage M2 polarization and the development of choroidal neovascularization.

Neovascular age-related macular degeneration (AMD), which is characterized by choroidal neovascularization (CNV), leads to vision loss. M2 m … acetylate XBP1s in RAW264.7 cells. Additionally, hypoxia-induced p300 enhanced the XBP-1s-mediated unfolded protein response (UPR), alleviated the proteasome-dependent degradation of XBP1s and enhanced the transcriptional activity of XBP1s for Herpud1. The hypoxia-induced p300/XBP1s/Herpud1 axis facilitated RAW264.7 cell M2 polarization. Knockdown of the p300/XBP1s/Herpud …

Crosstalk between endoplasmic reticulum stress and anti-viral activities: A novel therapeutic target for COVID-19.

The outbreak of COVID-19 caused by 2019-nCov/SARS-CoV-2 has become a pandemic with an urgent need for understanding the mechanisms and identifying a treatment. Viral infections including SARS-CoV are associated with increased levels of reactive oxygen species, disturbances of Ca++ caused by unfolded protein response (UPR) mediated by endoplasmic reticulum (ER) stress and is due to the exploitation of virus's own protein i.e., viroporins into the host cells. Several clinical trials are on-going including testing Remdesivir (anti-viral), Chloroquine and Hydroxychloroquine derivatives (anti-malar…

Detection and quantification of endoplasmic reticulum stress in living cells using the fluorescent compound, Thioflavin T.

The endoplasmic reticulum (ER) plays a central role in the co- and post-translational modification of many proteins. Disruption of these pro … gregates. We show that enhanced ThT-fluorescence correlates directly with established indicators of unfolded protein response activation. Furthermore, enhanced ThT-fluorescence can be detected in living cells within 20 min of application of an endoplasmic reticulum stress-inducing agent. ThT is capable of detecting endoplasmic reticulum stress induced by distinctly differe …

Mutant myocilin nonsecretion in vivo is not sufficient to cause glaucoma.

Glaucoma is a leading cause of blindness, affecting over 70 million people worldwide. Vision loss is the result of death of the retinal gang … or of abnormally folded protein. Surprisingly, the accumulated mutant protein does not activate the unfolded protein response and lead to elevated intraocular pressure or glaucoma in aged mice of different strains. These data suggest that production, apparent misfolding, and nonsecretion of mutant MYOC are not, by themselves, sufficient to cause glaucoma in vivo.

Peptide Inhibitors of Insulin Fibrillation: Current and Future Challenges.

Amyloidoses include a large variety of local and systemic diseases that share the common feature of protein unfolding or refolding into amyloid fibrils. The most studied amyloids are those directly involved in neurodegenerative diseases, while others, such as those formed by insulin, are surprisingly far less studied. Insulin is a very important polypeptide that plays a variety of biological roles and, first and foremost, is at the basis of the therapy of diabetic patients. It is well-known that it can form fibrils at the site of injection, leading to inflammation and immune response, in addit