UPR

Mϕs of patients with Alzheimer's disease and mild cognitive impairment (MCI) are defective in amyloid-β1-42 (Aβ) phagocytosis and have low resistance to apoptosis by Aβ. ω-3 in vitro and in vivo and the ω-3 mediator, resolvin D1, in vitro increase Aβ phagocytosis by Mϕs of patients with MCI. We have investigated the unfolded protein response (UPR) to endoplasmic reticulum (ER) stress by Mϕs in a longitudinal study of fish-derived, ω-3-supplemented patients with MCI. Patients in the apolipoprotein E (ApoE)e3/e3 subgroup over time exhibited an increase of protein kinase RNA-like ER kinase (PERK) expression, Aβ phagocytosis, intermediate M1-M2 Mϕ type, and a Mini-Mental State Examination (MMSE) rate of change of +1...

The unfolded protein response (UPR), which protects cells against accumulation of misfolded proteins in the ER, is induced in several age-associated degenerative diseases. However, sustained UPR activation has negative effects on cellular functions and may worsen disease symptoms. It remains unknown whether and how UPR components can be utilized to counteract chronic ER proteinopathies. We found that promotion of ER-associated degradation (ERAD) through upregulation of ERAD-enhancing α-mannosidase-like proteins (EDEMs) protected against chronic ER proteinopathy without inducing toxicity in a Drosophila model...

Stratum corneum forms the UV barrier. The effect of ultraviolet B (UVB) on normal skin was extensively studied; however, its effect on barrier perturbed skin remains undefined. Both barrier perturbation and UVB irradiation induce endoplasmic reticulum (ER) stress and unfolded protein response (UPR) in keratinocytes. Mild ER stress activates homeostatic UPR, while severe ER stress leads to abnormal UPR, promoting apoptosis and inflammation. Here, we investigated UV sensitivity and UVB-induced UPR in barrier-disrupted human skin and the effects of pseudoceramide-dominant emollient on UVB-induced skin responses...

Stress induced BSA (bovine serum albumin) protein aggregation is effectively mitigated in vitro by TUDCA (tauroursodeoxycholic acid) than by PBA (4- phenylbutyric acid), chemical chaperones approved by FDA for the treatment of biliary cirrhosis and urea cycle disorders respectively. TUDCA, unlike PBA, enhances trypsin mediated digestion of BSA. TUDCA activates PERK, an ER-resident kinase that phosphorylates the alpha-subunit of eukaryotic initiation factor2 (eIF2α) and promotes the expression of activated transcription factor 4 (ATF4) in HepG2 cells...

Disturbances in endoplasmic reticulum (ER) homeostasis create a condition termed ER stress. This activates the unfolded protein response (UPR), which alters the expression of many genes involved in ER quality control. We show here that ER stress causes the aggregation of proteins, most of which are not ER or secretory pathway proteins. Proteomic analysis of the aggregated proteins revealed enrichment for intrinsically aggregation-prone proteins rather than proteins which are affected in a stress-specific manner...

Curcumin, an extract from the turmeric rhizome (Curcuma longa), is known to exhibit anti-inflammatory, antioxidant, chemopreventive and antitumoral activities against aggressive and recurrent cancers. Accumulative data indicate that curcumin may induce cancer cell death. However, the detailed mechanism underlying its pro-apoptotic and anti-cancer effects remains to be elucidated. In the present study, we examined the signaling pathways triggered by curcumin, specifically, the exact molecular mechanisms of curcumin-induced apoptosis in highly metastatic human prostate cancer cells...

Endoplasmic reticulum (ER) stress and unfolded protein response (UPR) are involved in anti-human immunodeficiency virus (HIV) drugs and alcohol-induced liver disease in a significant number of patients infected with HIV. However, the precise mechanism by which the drugs and alcohol cause ER stress remains elusive. We found that ritonavir-boosted lopinavir (RL) activated two canonical UPR branches without activation of the third canonical activating transcription factor 6 (ATF6) branch in either HepG2 cells or primary mouse hepatocytes...

Besides its role in calcium (Ca(2+)) homeostasis, the sarco-endoplamic reticulum (SR/ER) controls protein folding and is tethered to mitochondria.Under pathophysiological conditions the unfolded protein response (UPR) is associated with disturbance in SR/ER-mitochondria crosstalk. Here, we investigated whether ER stress altered SR/ER-mitochondria links, Ca(2+) handling and muscle damage in WT (Wild Type) and mdx mice, the murine model of Duchenne Muscular Dystrophy (DMD). In WT mice, the SR/ER-mitochondria links were decreased in isolated FDB muscle fibers after injection of ER stress activator tunicamycin (TM)...

Acid fibroblast growth factor (aFGF) has shown neuroprotection in Alzheimer's disease (AD) models in previous studies, yet its mechanism is still uncertain. Here we report that the efficacy of Tat-haFGF14-154 is markedly increased when loaded cationic liposomes for intranasal delivery are intranasally administered to APP/PS1 mice. Our results demonstrated that liposomal Tat-haFGF14-154 treatment significantly ameliorated behavioral deficits, relieved brain Aβ burden, and increased the expression and activity of disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) in the brain...

Life is stressful. Organisms are repeatedly exposed to stressors that disrupt protein homeostasis (proteostasis), resulting in protein misfolding and aggregation. To sense and respond to proteotoxic perturbations, cells have evolved compartment-specific stress responses, such as the unfolded protein response of the endoplasmic reticulum (UPR(ER)). However, UPR(ER) function is impaired with age, which, we propose, creates a permissive environment for protein aggregation, unresolved ER stress, and chronic inflammation...

Homeostasis of the gut microbiota critically influences host health and aging. Developing genetically engineered probiotics holds great promise as a new therapeutic paradigm to promote healthy aging. Here, through screening 3,983 Escherichia coli mutants, we discovered that 29 bacterial genes, when deleted, increase longevity in the host Caenorhabditis elegans. A dozen of these bacterial mutants also protect the host from age-related progression of tumor growth and amyloid-beta accumulation. Mechanistically, we discovered that five bacterial mutants promote longevity through increased secretion of the polysaccharide colanic acid (CA), which regulates mitochondrial dynamics and unfolded protein response (UPR(mt)) in the host...

Physiological and pathological conditions that affect the folding capacity of the endoplasmic reticulum (ER) provoke ER stress and trigger the unfolded protein response (UPR). The UPR aims to either restore the balance between newly synthesized and misfolded proteins or if the damage is severe, to trigger cell death. However, the molecular events underlying the switch between repair and cell death are not well understood. The ER-resident chaperone BiP governs the UPR by sensing misfolded proteins and thereby releasing and activating the three mediators of the UPR: PERK, IRE1 and ATF6...

FAM46C is one of the most recurrently mutated genes in multiple myeloma (MM), however its role in disease pathogenesis has not been determined. Here we demonstrate that wild type (WT) FAM46C overexpression induces substantial cytotoxicity in MM cells. In contrast, FAM46C mutations found in MM patients abrogate this cytotoxicity, indicating a survival advantage conferred by the FAM46C mutant phenotype. WT FAM46C overexpression downregulated IRF4, CEBPB, and MYC and upregulated immunoglobulin (Ig) light chain and HSPA5/BIP Furthermore, pathway analysis suggests that enforced FAM46C expression activated the unfolded protein response (UPR) pathway and induced mitochondrial dysfunction...

Sequestosome 1 (SQSTM1) also known as ubiquitin-binding protein p62 (p62) is a cargo protein involved in the degradation of misfolded proteins via selective autophagy. Disruption of autophagy and resulting accumulation of misfolded proteins in the endoplasmic reticulum (ER) leads to ER stress. ER stress is implicated in several neurodegenerative diseases and obesity. As knockout of p62 (p62KO) reportedly induces obesity in mice, we examined how p62 contributes to ER stress and the ensuing unfolded protein response (UPR) in hypothalamus using mouse organotypic cultures in the present study...

The folding of secretory proteins is a well-understood mechanism, based on decades of research on endoplasmic reticulum (ER) chaperones. These chaperones interact with newly imported polypeptides close to the ER translocon. Classic examples for these proteins include the immunoglobulin binding protein (BiP/GRP78), and the lectins calnexin and calreticulin. Although not considered chaperones per se, the ER oxidoreductases of the protein disulfide isomerase (PDI) family complete the folding job by catalyzing the formation of disulfide bonds through cysteine oxidation...

Apigenin is a plant-derived flavonoid having anti-proliferative, anti-inflammatory and anti-angiogenic properties in chronic and metabolic diseases, and cancers. However, the functional role of apigenin remains to be identified in human endometriosis that is a benign inflammatory disease causing infertility, dysmenorrhea, dyspareunia, and chronic abdominal or pelvic pain. In the present study, we determined the effects of apigenin on two well-established human endometriosis cell lines (VK2/E6E7 and End1/E6E7)...

BACKGROUND: The most common and severe disease causing allele of Alpha 1-Antitrypsin Deficiency (1ATD) is Z-1AT. This protein aggregates in the endoplasmic reticulum, which is the main cause of liver disease in childhood. Based on recent evidences and on the frequency of liver disease occurrence in Z-1AT patients, it seems that liver disease progression is linked to still unknown genetic factors. METHODS: We used an innovative approach combining yeast genetic screens with next generation exome sequencing to identify and functionally characterize the genes involved in 1ATD associated liver disease...

Mutations in the gene for Immediate Early Response 3 Interacting Protein 1 (IER3IP1) cause permanent neonatal diabetes mellitus in human. The mechanisms involved have not been determined and the role of IER3IP1 in β-cell survival has not been characterized. In order to determine if there is a molecular link between IER3IP1 deficiency and β-cell survival and proliferation, we knocked down Ier3ip1 gene expression in mouse MIN6 insulinoma cells. IER3IP1 suppression induced apoptotic cell death which was associated with an increase in Bim and a decrease in Bcl-xL...

Altered cellular lipid composition activates the endoplasmic reticulum unfolded protein response (UPR) and UPR signaling effects important changes in lipid metabolism. Secondary effects on protein folding homeostasis likely contribute to UPR activation, but deletion of the unfolded protein stress-sensing luminal domain of the UPR transducers PERK and IRE1α does not abolish their responsiveness to lipid perturbation. This finding suggests that PERK and IRE1α also directly recognize the membrane aberrancy wrought by lipid perturbation...

Accumulation of profibrotic myofibroblasts is involved in the process of fibrosis development during idiopathic pulmonary fibrosis (IPF) pathogenesis. TGFB (transforming growth factor beta) is one of the major profibrotic cytokines for myofibroblast differentiation and NOX4 (NADPH oxidase 4) has an essential role in TGFB-mediated cell signaling. Azithromycin (AZM), a second-generation antibacterial macrolide, has a pleiotropic effect on cellular processes including proteostasis. Hence, we hypothesized that AZM may regulate NOX4 levels by modulating proteostasis machineries, resulting in inhibition of TGFB-associated lung fibrosis development...