Bisphenol A (BPA) is an industrial pollutant that can cause immune impairment. Selenium acts as an antioxidant, as selenium deficiency often accompanies oxidative stress, resulting in organ damage. ...This study is the first to demonstrate that BPA and/or selenium deficiency induce pyroptosis and ferroptosis-mediated thymic injury in chicken and chicken lymphoma cell (MDCC-MSB-1) via oxidative stress-induced endoplasmic reticulum (ER) stress. We established a broiler chicken model of BPA and/or selenium deficiency exposure and collected thymus samples as research subjects after 42 days. The results demonstrated that BPA or selenium deficiency led to a decrease in antioxidant enzyme activities (T-AOC, CAT, and GSH-Px), accumulation of peroxides (H2O2 and MDA), significant upregulation of ER stress-related markers (GRP78, IER 1, PERK, EIF-2α, ATF4, and CHOP), a significant increase in iron ion levels, significant upregulation of pyroptosis-related gene (NLRP3, ASC, Caspase1, GSDMD, IL-18 and IL-1β), significantly increase ferroptosis-related genes (TFRC, COX2) and downregulate GPX4, HO-1, FTH, NADPH. In vitro experiments conducted in MDCC-MSB-1 cells confirmed the results, demonstrating that the addition of antioxidant (NAC), ER stress inhibitor (TUDCA) and pyroptosis inhibitor (Vx765) alleviated oxidative stress, endoplasmic reticulum stress, pyroptosis, and ferroptosis. Overall, this study concludes that the combined effects of oxidative stress and ER stress mediate pyroptosis and ferroptosis in chicken thymus induced by BPA exposure and selenium deficiency.
Background: Vascular endothelial cell dysfunction, characterized by cell apoptosis and migration, plays a crucial role in ischaemia/reperfusion (I/R) injury, a common aspect of cardiovascular ...diseases. Recent studies have suggested that non-coding RNAs, such as circular RNAs (circRNA), play a role in cell dysfunction in I/R injury, although the detailed mechanism is unclear.
Methods: Human umbilical vein endothelial cells (HUVECs) were used for in vitro I/R model. Protein expression was detected by western blotting (WB) and immunocytochemistry. The CRISPR/Cas9 system, WB, cell viability assays, Hoechst staining and a 3D migration model were used to explore functional changes. RNA expression was evaluated using quantitative real-time PCR and a FISH assay combined with lentivirus transfection regulating circRNAs and miRNAs. A mouse myocardial I/R model using C57 mice was established to confirm the in vitro findings.
Results: In HUVECs, I/R induced a significant time-dependent decrease in HECTD1 associated with an approximately 45% decrease in cell viability and increases in cell apoptosis and migration, which were attenuated by HECTD1 overexpression. I/R-induced upregulation of endoplasmic reticulum stress was also attenuated HECTD1 overexpression. Moreover, miR-143 mimics inhibited HECTD1 expression, which was restored by circDLGAP4 overexpression, providing insight as to the molecular mechanism of I/R-induced HECTD1 in endothelial cell dysfunction.
Conclusion: Our results suggest a critical role for circDLGAP4 and HECTD1 in endothelial cell dysfunction induced by I/R, providing novel insight into potential therapeutic targets for the treatment of myocardial ischaemia.
Organoids enable in vitro modeling of complex developmental processes and disease pathologies. Like most 3D cultures, organoids lack sufficient oxygen supply and therefore experience cellular stress. ...These negative effects are particularly prominent in complex models, such as brain organoids, and can affect lineage commitment. Here, we analyze brain organoid and fetal single‐cell RNA sequencing (scRNAseq) data from published and new datasets, totaling about 190,000 cells. We identify a unique stress signature in the data from all organoid samples, but not in fetal samples. We demonstrate that cell stress is limited to a defined subpopulation of cells that is unique to organoids and does not affect neuronal specification or maturation. We have developed a computational algorithm, Gruffi, which uses granular functional filtering to identify and remove stressed cells from any organoid scRNAseq dataset in an unbiased manner. We validated our method using six additional datasets from different organoid protocols and early brains, and show its usefulness to other organoid systems including retinal organoids. Our data show that the adverse effects of cell stress can be corrected by bioinformatic analysis for improved delineation of developmental trajectories and resemblance to in vivo data.
Synopsis
Cellular stress in 3D organoids due to insufficient oxygen transport can affect faithful lineage commitment and disease modeling. This work identifies a subpopulation of stressed cells characterized by a distinct gene expression signature that can be removed from scRNAseq datasets for better evaluation of fetal developmental trajectories.
ER‐ and glycolytic stress are found accross organoid protocols.
Stressed cells in 3D organoids form a separate cell state that is not found in vivo and that can be separated bioinformatically.
The presence of stressed cells in organoids does not affect cell‐type specification or the maturation of non‐stressed neurons.
Granular functional filtering (Gruffi) removes stressed cells from the single‐cell datasets but retains cell types found in vivo.
Stress removal leads to clearer developmental trajectories.
A unique stress signature found in in brain organoid samples but not in fetal samples can be quantified and removed from scRNAseq datasets using a new algorithm.
Background and aims
Non‐alcoholic fatty liver disease (NAFLD) is becoming increasingly prevalent and nutrition intervention remains the most important therapeutic approach for NAFLD. Our aim was to ...investigate whether low‐ (LP) or high‐protein (HP) diets are more effective in reducing liver fat and reversing NAFLD and which mechanisms are involved.
Methods
19 participants with morbid obesity undergoing bariatric surgery were randomized into two hypocaloric (1500‐1600 kcal/day) diet groups, a low protein (10E% protein) and a high protein (30E% protein), for three weeks prior to surgery. Intrahepatic lipid levels (IHL) and serum fibroblast growth factor 21 (FGF21) were measured before and after the dietary intervention. Autophagy flux, histology, mitochondrial activity and gene expression analyses were performed in liver samples collected during surgery.
Results
IHL levels decreased by 42.6% in the HP group, but were not significantly changed in the LP group despite similar weight loss. Hepatic autophagy flux and serum FGF21 increased by 66.7% and 42.2%, respectively, after 3 weeks in the LP group only. Expression levels of fat uptake and lipid biosynthesis genes were lower in the HP group compared with those in the LP group. RNA‐seq analysis revealed lower activity of inflammatory pathways upon HP diet. Hepatic mitochondrial activity and expression of β‐oxidation genes did not increase in the HP group.
Conclusions
HP diet more effectively reduces hepatic fat than LP diet despite of lower autophagy and FGF21. Our data suggest that liver fat reduction upon HP diets result primarily from suppression of fat uptake and lipid biosynthesis.
The endoplasmic reticulum (ER) is the major site of calcium storage and protein folding. It has a unique oxidizing-folding environment due to the predominant disulfide bond formation during the ...process of protein folding. Alterations in the oxidative environment of the ER and also intra-ER Ca2+ cause the production of ER stress-induced reactive oxygen species (ROS). Protein disulfide isomerases, endoplasmic reticulum oxidoreductin-1, reduced glutathione and mitochondrial electron transport chain proteins also play crucial roles in ER stress-induced production of ROS. In this article, we discuss ER stress-associated ROS and related diseases, and the current understanding of the signaling transduction involved in ER stress.
Lipid droplet functions beyond energy storage Welte, Michael A.; Gould, Alex P.
Biochimica et biophysica acta. Molecular and cell biology of lipids,
10/2017, Volume:
1862, Issue:
10
Journal Article
Peer reviewed
Open access
Lipid droplets are cytoplasmic organelles that store neutral lipids and are critically important for energy metabolism. Their function in energy storage is firmly established and increasingly well ...characterized. However, emerging evidence indicates that lipid droplets also play important and diverse roles in the cellular handling of lipids and proteins that may not be directly related to energy homeostasis. Lipid handling roles of droplets include the storage of hydrophobic vitamin and signaling precursors, and the management of endoplasmic reticulum and oxidative stress. Roles of lipid droplets in protein handling encompass functions in the maturation, storage, and turnover of cellular and viral polypeptides. Other potential roles of lipid droplets may be connected with their intracellular motility and, in some cases, their nuclear localization. This diversity highlights that lipid droplets are very adaptable organelles, performing different functions in different biological contexts. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
•Lipid droplets have important functions beyond energy homeostasis.•They store vitamins, signaling precursors, and other hydrophobic molecules.•They mitigate some harmful effects of ER and oxidative stress.•They function in protein maturation, storage, and turnover.•They are motile and can exist in the nucleus.
•Autophagy and UPR interaction underlies ERS response outcomes.•ERS modulates mitochondrial biogenesis and function.•Ubiquitin ligases fine-tune the ERS response.
Cellular stress, induced by external ...or internal cues, activates several well-orchestrated processes aimed at either restoring cellular homeostasis or committing to cell death. Those processes include the unfolded protein response (UPR), autophagy, hypoxia, and mitochondrial function, which are part of the global endoplasmic reticulum (ER) stress (ERS) response. When one of the ERS elements is impaired, as often occurs under pathological conditions, overall cellular homeostasis may be perturbed. Further, activation of the UPR could trigger changes in mitochondrial function or autophagy, which could modulate the UPR, exemplifying crosstalk processes. Among the numerous factors that control the magnitude or duration of these processes are ubiquitin ligases, which govern overall cellular stress outcomes. Here we summarize crosstalk among the fundamental processes governing ERS responses.
Osteoarthritis (OA) is a chronic degenerative disease that affects the whole synovial joint. OA causes severe pain and disability that significantly affects the livelihood of an individual and incurs ...a huge socioeconomic burden. Current management strategies are limited to supporting functional improvement with physiotherapy and pain reduction as there are no drugs available that can reverse the progression of OA with only joint replacement surgery for late stage OA. OA is associated with advancing age and obesity, both of which compromise the functions of key endoplasmic reticulum (ER) molecular chaperones leading to improper protein folding and ER stress. Failure to restore protein homeostasis leads to increased cellular stress and eventually apoptotic cell death. Cartilage is avascular and is dependent on its constituent cells, chondrocytes, for extracellular matrix maintenance. Chondrocytes have limited proliferative capacity and their apoptosis eventually leads to extracellular matrix loss and cartilage degeneration. Recent studies on attenuating ER stress and chondrocytes apoptosis offer a credible strategy for reducing OA progression. The established roles of ER stress responses in OA have paved the way for targeted drug discovery studies aiming to mitigate ER stress and OA progression. In this review, in vitro, pre-clinical and clinical evidence of naturally-derived ER stress inhibitors for OA, the prospect and challenges in bringing these compounds to clinics are discussed.
The pathological mechanisms underlying increased outflow resistance at the trabecular meshwork (TM) that is responsible for elevating intraocular pressure (IOP) have not been fully delineated. Recent ...studies have shown that progressive accumulation of misfolded proteins and induction of endoplasmic reticulum (ER) stress is associated with the pathophysiology of glaucomatous TM damage and IOP elevation. We have shown that known causes of human glaucoma, including expression of mutant myocilin or dexamethasone treatment induce abnormal protein accumulation and ER stress in the TM in vitro and in vivo models. To cope up with abnormal protein accumulation, TM cells activate a cytoprotective pathway of unfolded protein response (UPR). However, chronic ER stress can lead to TM dysfunction and IOP elevation. Using cell culture, mouse models, and human postmortem tissues as well as genetic and pharmacological manipulations, we have analyzed ER stress and UPR mediators in the glaucomatous TM damage and IOP elevation. In this chapter, we have described a detailed protocol for the analysis of protein misfolding and ER stress in TM cells and tissues and its association with glaucomatous TM damage and IOP elevation.
The secretory capacity of a cell is constantly challenged by physiological demands and pathological perturbations. To adjust and match the protein-folding capacity of the endoplasmic reticulum (ER) ...to changing secretory needs, cells employ a dynamic intracellular signaling pathway known as the unfolded protein response (UPR). Homeostatic activation of the UPR enforces adaptive programs that modulate and augment key aspects of the entire secretory pathway, whereas maladaptive UPR outputs trigger apoptosis. Here, we discuss recent advances into how the UPR integrates information about the intensity and duration of ER stress stimuli in order to control cell fate. These findings are timely and significant because they inform an evolving mechanistic understanding of a wide variety of human diseases, including diabetes mellitus, neurodegeneration, and cancer, thus opening up the potential for new therapeutic modalities to treat these diverse diseases.
Maintenance of endoplasmic reticulum (ER) proteostasis is controlled by a dynamic signaling network known as the unfolded protein response (UPR). IRE1α is an ER-located kinase and endoribonuclease that operates as a major ER stress transducer, mediating the establishment of adaptive and pro-apoptotic programs. Here, Hetz and Papa discuss recent advances of their understanding on how the UPR is regulated and its significance to a variety of different human diseases.
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