High Glucose Inhibits Neural Stem Cell Differentiation Through Oxidative Stress and Endoplasmic Reticulum Stress

Ethionine-induced S-adenosylmethionine deficiency suppressed H3K27me3 and cell differentiation during neural tube development in mice

S-adenosylmethionine (SAM) as a major methyl donor plays a key role in methylation modification in vivo, and its disorder was closely related to neural tube defects (NTDs). However, the exact mechanism between SAM deficiency and NTDs remained unclearly. Hence, we investigated the association between histone methylation modification and cell differentiation in NTDs mice induced by SAM deficiency. The levels of SAM and SAH (S-adenosylhomocysteine) were determined by enzyme linked immunosorbent assay (ELISA). The level of histone methylation, β-catenin were analyzed by Western blot, reversing transcription and quantitative PCR (RT-qPCR) and immunofluorescence. The results showed that the incidence rate of NTDs induced by ethionine were 46.2%. Post treatment of ethionine combined with SAM, the incidence rate of NTDs was reduced to 26.2%. The level of SAM was significantly decreased (p < 0.05) and a reduction in the SAM/SAH ratio was observed after entionine treatment. The SAM deficiency caused the reduction of H3K27me3 modifications and the elevated UTX activity (p < 0.05), and inhibited the expressions of β-catenin. The differentiations of NSCs into neurons and oligodendrocytes were inhibited under SAM deficiency (p < 0.05). These results indicated that the SAM deficiency led to reduce H3K27me3 modifications, prevented the β-catenin signaling pathway and NSCs differentiation, which provided an understanding of the novel function of epigenetic regulation in NTDs.

CRISPR-Cas9 screens reveal regulators of ageing in neural stem cells

Ageing impairs the ability of neural stem cells (NSCs) to transition from quiescence to proliferation in the adult mammalian brain. Functional decline of NSCs results in the decreased production of new neurons and defective regeneration following injury during ageing1-4. Several genetic interventions have been found to ameliorate old brain function5-8, but systematic functional testing of genes in old NSCs-and more generally in old cells-has not been done. Here we develop in vitro and in vivo high-throughput CRISPR-Cas9 screening platforms to systematically uncover gene knockouts that boost NSC activation in old mice. Our genome-wide screens in primary cultures of young and old NSCs uncovered more than 300 gene knockouts that specifically restore the activation of old NSCs. The top gene knockouts are involved in cilium organization and glucose import. We also establish a scalable CRISPR-Cas9 screening platform in vivo, which identified 24 gene knockouts that boost NSC activation and the production of new neurons in old brains. Notably, the knockout of Slc2a4, which encodes the GLUT4 glucose transporter, is a top intervention that improves the function of old NSCs. Glucose uptake increases in NSCs during ageing, and transient glucose starvation restores the ability of old NSCs to activate. Thus, an increase in glucose uptake may contribute to the decline in NSC activation with age. Our work provides scalable platforms to systematically identify genetic interventions that boost the function of old NSCs, including in vivo, with important implications for countering regenerative decline during ageing.

Rigor and reproducibility in human brain organoid research: Where we are and where we need to go

Human brain organoid models have emerged as a promising tool for studying human brain development and function. These models preserve human genetics and recapitulate some aspects of human brain development, while facilitating manipulation in an in vitro setting. Despite their potential to transform biology and medicine, concerns persist about their fidelity. To fully harness their potential, it is imperative to establish reliable analytic methods, ensuring rigor and reproducibility. Here, we review current analytical platforms used to characterize human forebrain cortical organoids, highlight challenges, and propose recommendations for future studies to achieve greater precision and uniformity across laboratories.

Indole-3-propionic acid attenuates high glucose induced ER stress response and augments mitochondrial function by modulating PERK-IRE1-ATF4-CHOP signalling in experimental diabetic neuropathy

OBJECTIVES

We aimed to evaluate the neuroprotective effect of Indole-3-propionic acid (IPA) against streptozotocin (STZ) induced diabetic peripheral neuropathy (DPN) in rats and in high glucose (HG) induced neurotoxicity in neuro2a (N2A) cells.

METHODS

Diabetes was induced in male SD rats STZ (55 mg/kg, i.p.) and IPA (10 and 20 mg/kg, p.o.) was administered for two weeks, starting from sixth week after diabetes induction. Neurobehavioral, functional assessments were made, and various molecular studies were performed to evaluate the effect of IPA on HG induced ER stress and mitochondrial dysfunction in sciatic nerves, DRGs and in N2A cells.

RESULTS

Diabetic rats and high glucose exposed N2A cells showed marked increase in oxidative damage accompanied by ER stress and mitochondrial dysfunction along with increased apoptotic markers. IPA treatment for two weeks markedly alleviated these changes and attenuated pain behaviour.

CONCLUSION

IPA exhibited neuroprotective activity against hyperglycaemic insults.

Targeting Nrf2 signaling pathway by quercetin in the prevention and treatment of neurological disorders: An overview and update on new developments

BACKGROUND

Neurological disorders (NLDs) are widely acknowledged as a significant public health concern worldwide. Stroke, Alzheimer's disease (AD), and traumatic brain injury (TBI) are three of these disorders that have sparked major study attention. Neurological dysfunction, protein buildup, oxidation and neuronal injury, and aberrant mitochondria are all prevalent neuropathological hallmarks of these disorders. The signaling cascade of nuclear factor erythroid 2 related factor 2 (Nrf2) shares all of them as a common target. Several studies have found that overexpression of Nrf2 is a promising treatment method in NLDs. Effective treatment of these disorders continues to be a universal concern regardless of various medicines. In order to treat a variety of neurological problems, organic remedies may provide an alternative treatment. It has been demonstrated that polyphenols like quercetin (Que) offer considerable capabilities for treating NLDs. One of Que's greatest key targets, Nrf2, has the capacity to control the production of a number of cytoprotective enzymes that exhibit neuroprotective, detoxifying, and antioxidative effects. Additionally, Que enhanced the expression of Nrf2 and inhibited alterations in the shape and death of neurons in the hippocampus.

OBJECTIVE

In this review, we have focused on Que's medicinal prospects as a neuroprotective drug.

METHODS

PubMed, Scopus, Science Direct, and Google Scholar were used to search articles for this study.

RESULTS

The findings of this research demonstrate that (1) Que protected the blood-brain barrier via stimulating Nrf2 in animal stroke, which alleviated ischemic reperfusion and motor dysfunction. (2) By triggering the Nrf2 pathway, Que reduced the neuroinflammation and oxidative damage brought on by TBI in the cortex. (3) In an experimental model of AD, Que enhanced cognitive function by decreasing A1-4, antioxidant activity, and Nrf2 levels in the brain.

CONCLUSION

We discuss recent research on Que-mediated Nrf2 expression in the management of several NLDs in this paper.

Integration of 3D-printed cerebral cortical tissue into an ex vivo lesioned brain slice

Engineering human tissue with diverse cell types and architectures remains challenging. The cerebral cortex, which has a layered cellular architecture composed of layer-specific neurons organised into vertical columns, delivers higher cognition through intricately wired neural circuits. However, current tissue engineering approaches cannot produce such structures. Here, we use a droplet printing technique to fabricate tissues comprising simplified cerebral cortical columns. Human induced pluripotent stem cells are differentiated into upper- and deep-layer neural progenitors, which are then printed to form cerebral cortical tissues with a two-layer organization. The tissues show layer-specific biomarker expression and develop a structurally integrated network of processes. Implantation of the printed cortical tissues into ex vivo mouse brain explants results in substantial structural implant-host integration across the tissue boundaries as demonstrated by the projection of processes and the migration of neurons, and leads to the appearance of correlated Ca2+ oscillations across the interface. The presented approach might be used for the evaluation of drugs and nutrients that promote tissue integration. Importantly, our methodology offers a technical reservoir for future personalized implantation treatments that use 3D tissues derived from a patient's own induced pluripotent stem cells.

Exposure to nonylphenol in early life causes behavioural deficits related with autism spectrum disorders in rats

Early-life exposure to environmental endocrine disruptors (EDCs) is a potential risk factor for autism spectrum disorder (ASD). Exposure to nonylphenol (NP), a typical EDC, is known to cause some long-term behavioural abnormalities. Moreover, these abnormal behaviours are the most frequent psychiatric co-morbidities in ASD. However, the direct evidence for the link between NP exposure in early life and ASD-like behavioural phenotypes is still missing. In the present study, typical ASD-like behaviours induced by valproic acid treatment were considered as a positive behavioural control. We investigated impacts on social behaviours following early-life exposure to NP, and explored effects of this exposure on neuronal dendritic spines, mitochondria function, oxidative stress, and endoplasmic reticulum (ER) stress. Furthermore, primary cultured rat neurons were employed as in vitro model to evaluate changes in dendritic spine caused by exposure to NP, and oxidative stress and ER stress were specifically modulated to further explore their roles in these changes. Our results indicated rats exposed to NP in early life showed mild ASD-like behaviours. Moreover, we also found the activation of ER stress triggered by oxidative stress may contribute to dendritic spine decrease and synaptic dysfunction, which may underlie neurobehavioural abnormalities induced by early-life exposure to NP.

Metformin attenuates sevoflurane-induced neurogenesis damage and cognitive impairment: involvement of the Nrf2/G6PD pathway

Anesthetics such as sevoflurane are commonly administered to infants and children. However, the possible neurotoxicity caused by prolonged or repetitive exposure to it should be a concern. The neuroprotective effects of metformin are observed in many models of neurological disorders. In this study, we investigated whether metformin could reduce the developmental neurotoxicity induced by sevoflurane exposure in neonatal rats and the potential mechanism. Postnatal day 7 (PND 7) Sprague-Dawley rats and neural stem cells (NSCs) were treated with normal saline or metformin before sevoflurane exposure. The Morris water maze (MWM) was used to observe spatial memory and learning at PND 35-42. Immunofluorescence staining was used to detect neurogenesis in the subventricular zone (SVZ) of the lateral ventricle and the subgranular zone (SGZ) of the dentate gyrus at PND 14. MTT assays, immunofluorescence staining, and TUNEL staining were used to assess the viability, proliferation, differentiation, and apoptosis of NSCs. Western blotting and ELISA were used to assess the protein expression of cleaved caspase-3, nuclear factor erythroid 2-related factor 2 (Nrf2), and glucose-6-phosphate dehydrogenase (G6PD) pathway-related molecules. Exposure to sevoflurane resulted in late cognitive defects, impaired neurogenesis in both the SVZ and SGZ, reduced NSC viability and proliferation, increased NSC apoptosis, and decreased protein expression of G6PD in vitro. Metformin pretreatment attenuated sevoflurane-induced cognitive functional decline and neurogenesis inhibition. Metformin pretreatment also increased the protein expression of Nrf2 and G6PD. However, treatment with the Nrf2 inhibitor, ML385 or the G6PD inhibitor, dehydroepiandrosterone (DHEA) reversed the protective effect of metformin on sevoflurane-induced NSC damage in vitro. Our findings suggested that metformin could reduce sevoflurane-induced neurogenesis damage and neurocognitive defects in the developing rat brain by influencing the Nrf2/G6PD signaling pathways.

Benefits of the Neurogenic Potential of Melatonin for Treating Neurological and Neuropsychiatric Disorders

There are several neurological diseases under which processes related to adult brain neurogenesis, such cell proliferation, neural differentiation and neuronal maturation, are affected. Melatonin can exert a relevant benefit for treating neurological disorders, given its well-known antioxidant and anti-inflammatory properties as well as its pro-survival effects. In addition, melatonin is able to modulate cell proliferation and neural differentiation processes in neural stem/progenitor cells while improving neuronal maturation of neural precursor cells and newly created postmitotic neurons. Thus, melatonin shows relevant pro-neurogenic properties that may have benefits for neurological conditions associated with impairments in adult brain neurogenesis. For instance, the anti-aging properties of melatonin seem to be linked to its neurogenic properties. Modulation of neurogenesis by melatonin is beneficial under conditions of stress, anxiety and depression as well as for the ischemic brain or after a brain stroke. Pro-neurogenic actions of melatonin may also be beneficial for treating dementias, after a traumatic brain injury, and under conditions of epilepsy, schizophrenia and amyotrophic lateral sclerosis. Melatonin may represent a pro-neurogenic treatment effective for retarding the progression of neuropathology associated with Down syndrome. Finally, more studies are necessary to elucidate the benefits of melatonin treatments under brain disorders related to impairments in glucose and insulin homeostasis.

High glucose causes developmental abnormalities in neuroepithelial cysts with actin and HK1 distribution changes

It has been reported that the offspring of diabetic pregnant women have an increased risk for neural tube defects. Previous studies in animal models suggested that high glucose induces cell apoptosis and epigenetic changes in the developing neural tube. However, effects on other cellular aspects such as the cell shape changes were not fully investigated. Actin dynamics plays essential roles in cell shape change. Disruption on actin dynamics is known to cause neural tube defects. In the present study, we used a 3D neuroepithelial cyst model and a rosette model, both cultured from human embryonic stem cells, to study the cellular effects caused by high glucose. By using these models, we observed couple of new changes besides increased apoptosis. First, we observed that high glucose disturbed the distribution of pH3 positive cells in the neuroepithelial cysts. Secondly, we found that high glucose exposure caused a relatively smaller actin inner boundary enclosed area, which was unlikely due to osmolarity changes. We further investigated key glucose metabolic enzymes in our models and the results showed that the distribution of hexokinase1 (HK1) was affected by high glucose. We observed that hexokinase1 has an apical-basal polarized distribution and is highest next to actin at the boundaries. hexokinase1 was more diffused and distributed less polarized under high glucose condition. Together, our observations broadened the cellular effects that may be caused by high glucose in the developing neural tube, especially in the secondary neurulation process.

Association between air pollutants and neural tube defects during pregnancy in Lanzhou, China: a time series analysis

Few studies have evaluated the association between air pollutants and neural tube defects (NTDs). Moreover, the existing research ignores the lag effect of air pollution on health and provides inconsistent epidemiological evidence. We aim to estimate the association between air pollution and NTDs during the first trimester of pregnancy and identify specific susceptible windows. Birth data was collected from the Birth Defects Surveillance Network in Lanzhou from September 1, 2014, to December 31, 2019. Air quality and meteorological data were collected from ambient air monitoring stations and China Meteorological Data Network. The log connection function of the Poisson distribution function is used to establish a DLNM model to estimate the exposure-effect relationship and exposure-lag relationship association between air pollutants levels and NTDs. There were 320,787 perinatal infants in Lanzhou from September 1, 2014, to December 31, 2019, and 486 cases of NTDs (1.5‰). The result indicates that exposure to inhalable particles (PM₁₀) at lag 2-4 weeks was significantly associated with the risk of NTDs, with the most significant impact at the lag 2 week (RR=1.048, 95%CI, 1.015-1.084). Exposure to fine particulate matter (PM_2.5) at the lag 2 week was significantly associated with the risk of NTDs, with the most significant impact at the lag 2 week (RR=1.077, 95%CI, 1.004-1.155). Exposure to sulfur dioxide (SO₂) and nitrogen dioxide (NO₂) at lag 3-6weeks was significantly associated with the risk of NTDs, with the most significant impact at the lag 4 week (RR=1.220, 95%CI, 1.105-1.348; RR=1.143, 95%CI, 1.048-1.245). This study provides further evidence that exposure to air pollutants in the first trimester of pregnancy significantly increases the risk of neural tube defects.

Antiglycoxidative properties of amantadine – a systematic review and comprehensive in vitro study

An important drug used in the treatment of Parkinson’s disease is amantadine. We are the first to perform a comprehensive study based on various glycation and oxidation factors, determining the impact of amantadine on protein glycoxidation. Sugars (glucose, fructose, galactose) and aldehydes (glyoxal, methylglyoxal) were used as glycation agents, and chloramine T was used as an oxidant. Glycoxidation biomarkers in albumin treated with amantadine were generally not different from the control group (glycation/oxidation factors), indicating that the drug did not affect oxidation and glycation processes. Molecular docking analysis did not reveal strong binding sites of amantadine on the bovine serum albumin structure. Although amantadine poorly scavenged hydroxyl radical and hydrogen peroxide, it had significantly lower antioxidant and antiglycation effect than all protein oxidation and glycation inhibitors. In some cases, amantadine even demonstrated glycoxidant, proglycation, and prooxidant properties. In summary, amantadine exhibited weak antioxidant properties and a lack of antiglycation activity.

β-Hydroxybutyric acid improves cognitive function in a model of heat stress by promoting adult hippocampal neurogenesis

Heat stress has multiple potential effects on the brain, such as neuroinflammation, neurogenesis defects, and cognitive impairment. β-hydroxybutyric acid (BHBA) has been demonstrated to play neuroprotective roles in various models of neurological diseases. In the present study, we investigated the efficacy of BHBA in alleviating heat stress-induced impairments of adult hippocampal neurogenesis and cognitive function, as well as the underlying mechanisms. Mice were exposed to 43 ℃ for 15 min for 14 days after administration with saline, BHBA, or minocycline. Here, we showed for the first time that BHBA normalized memory ability in the heat stress-treated mice and attenuated heat stress-impaired hippocampal neurogenesis. Consistently, BHBA noticeably improved the synaptic plasticity in the heat stress-treated hippocampal neurons by inhibiting the decrease of synapse-associated proteins and the density of dendritic spines. Moreover, BHBA inhibited the expression of cleaved caspase-3 by suppressing endoplasmic reticulum (ER) stress, and increased the expression of brain-derived neurotrophic factor (BDNF) in the heat stress-treated hippocampus by activating the protein kinase B (Akt)/cAMP response element binding protein (CREB) and methyl-CpG binding protein 2 (MeCP2) pathways. These findings indicate that BHBA is a potential agent for improving cognitive functions in heat stress-treated mice. The action may be mediated by ER stress, and Akt-CREB-BDNF and MeCP2 pathways to improve adult hippocampal neurogenesis and synaptic plasticity.

Hesperidin Protects SH−SY5Y Neuronal Cells against High Glucose−Induced Apoptosis via Regulation of MAPK Signaling

Neurodegenerative diseases are associated with neuronal cell death through apoptosis. Apoptosis is tightly associated with the overproduction of reactive oxygen species (ROS), and high glucose levels contribute to higher oxidative stress in diabetic patients. Hesperidin, a natural active compound, has been reported to scavenge free radicals. Only a few studies have explored the protective effects of hesperidin against high glucose−induced apoptosis in SH−SY5Y neuronal cells. Glucose stimulated neuronal cells to generate excessive ROS and caused DNA damage. In addition, glucose triggered endoplasmic reticulum stress and upregulated cytoplasmic as well as mitochondrial calcium levels. Hesperidin inhibited glucose−induced ROS production and mitigated the associated DNA damage and endoplasmic reticulum stress. The downregulation of antiapoptotic protein Bcl−2 following glucose treatment was reversed by a hesperidin treatment. Furthermore, hesperidin repressed the glucose−induced Bcl−2−associated X protein, cleaved caspase−9, and cleaved caspase−3. Hesperidin also suppressed the glucose−induced phosphorylation of extracellular signal−regulated kinase and c−Jun N−terminal kinase. The current results confirmed that hesperidin could protect neuronal cells against glucose−induced ROS. Mechanistically, hesperidin was shown to promote cell viability via attenuation of the mitogen−activated protein kinase signaling pathway.

Myeloid-derived growth factor regulates high glucose-mediated apoptosis of gingival fibroblasts and induce AKT pathway activation and nuclear factor κB pathway inhibition

Background

/purpose: Periodontal disease is a chronic inflammatory disease that occurs in the tissues that support and attach teeth. There is considerable evidence of a relationship between diabetes and periodontal disease. Emerging studies have reported that myeloid-derived growth factor (MYDGF) can inhibit apoptosis and inflammation. The purpose of this study was to investigate whether MYDGF mediates the role of hyperglycemia in fibroblasts in periodontitis tissues.

Materials and methods

Fibroblasts were isolated and cultured from normal gums. Gene expression levels were detected by RT-PCR. The protein level was detected by western blotting. Cell viability was determined by MTT assay. To investigate the role of MYDGF, the plasmid was transfected into fibroblasts. The expression levels of cytokines were determined by ELISA.

Results

High glucose can down-regulate the expression of MYDGF in human gingival fibroblasts in a time-dependent manner, and decrease the fibroblast activity. SOD level was decreased and MDA level was increased in gingival fibroblasts by high glucose. High glucose up-regulates pro-apoptotic indicator Bax, down-regulates anti-apototic indicator Bcl-2, and increased endoplasmic reticulum stress related indicators Nox 2, GRP78, ATF6, and PERK. In addition, high glucose increased TNF-α, IL-1β, IL-8 and CXCL1 protein levels in fibroblasts. Our study also found that high glucose inhibits the AKT signaling pathway and activates the nuclear factor κB (NF-κB) pathway. Interestingly, overexpression of MYDGF reversed these effects.

Conclusion

MYDGF is down-regulated in gingival fibroblasts induced by high glucose. Overexpression of MYDGF inhibits apoptosis induced by high glucose, inhibits oxidative stress and cytokine secretion of gingival fibroblasts induced by high glucose, and induces AKT pathway activation and NF-κB pathway inhibition.

The Interaction of mTOR and Nrf2 in Neurogenesis and Its Implication in Neurodegenerative Diseases

Neurogenesis occurs in the brain during embryonic development and throughout adulthood. Neurogenesis occurs in the hippocampus and under normal conditions and persists in two regions of the brain—the subgranular zone (SGZ) in the dentate gyrus of the hippocampus and the subventricular zone (SVZ) of the lateral ventricles. As the critical role in neurogenesis, the neural stem cells have the capacity to differentiate into various cells and to self-renew. This process is controlled through different methods. The mammalian target of rapamycin (mTOR) controls cellular growth, cell proliferation, apoptosis, and autophagy. The transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2) is a major regulator of metabolism, protein quality control, and antioxidative defense, and is linked to neurogenesis. However, dysregulation in neurogenesis, mTOR, and Nrf2 activity have all been associated with neurodegenerative diseases such as Alzheimer’s, Huntington’s, and Parkinson’s. Understanding the role of these complexes in both neurogenesis and neurodegenerative disease could be necessary to develop future therapies. Here, we review both mTOR and Nrf2 complexes, their crosstalk and role in neurogenesis, and their implication in neurodegenerative diseases.

Exposure to polystyrene microplastics reduces regeneration and growth in planarians

The potential adverse effects of microplastics (MPs) on ecosystems and human health have received much attention in recent years. However, only limited data are available on the mechanisms for the uptake, distribution, and effects of MPs in freshwater organisms, especially with respect to tissue repair, regeneration and impairment of stem cell functions. To address this knowledge gap, we conducted exposure experiments in which planarians (Dugesia japonica) were exposed to polystyrene (PS)-MPs mixed in liver homogenate and examined the tissue growth and regeneration, stem cell functions, and oxidative stress. The body and blastema areas decreased upon exposure to PS-MPs, indicating that the growth and regeneration of planarians were delayed. The proliferation and differentiation processes of stem cells were inhibited, and the proportion of mitotic stem cells decreased, which may be related to the activation of the TGFβ/SMAD4 and Notch signaling pathways. The enhancement of antioxidant enzyme activities and malondialdehyde on the first day of exposure to PS-MPs confirmed the oxidative stress response of planarians to PS-MPs. The present study demonstrated the likelihood of biotoxicity induced by PS-MPs. These results will provide clues for further investigations into the potential risks of PS-MPs to human stem cells.

Dimethyloxalylglycine (DMOG), a Hypoxia Mimetic Agent, Does Not Replicate a Rat Pheochromocytoma (PC12) Cell Biological Response to Reduced Oxygen Culture

Cells respond to reduced oxygen availability predominately by activation of the hypoxia-inducible factor (HIF) pathway. HIF activation upregulates hundreds of genes that help cells survive in the reduced oxygen environment. The aim of this study is to determine whether chemical-induced HIF accumulation mimics all aspects of the hypoxic response of cells. We compared the effects of dimethyloxalylglycine (DMOG) (a HIF stabiliser) on PC12 cells cultured in air oxygen (20.9% O_2, AO) with those cultured in either intermittent 20.9% O₂ to 2% O₂ (IH) or constant 2% O₂ (CN). Cell viability, cell cycle, HIF accumulation, reactive oxygen species (ROS) formation, mitochondrial function and differentiation were used to characterise the PC12 cells and evaluate the impact of DMOG. IH and CN culture reduced the increase in cell numbers after 72 and 96 h and MTT activity after 48 h compared to AO culture. Further, DMOG supplementation in AO induced a dose-dependent reduction in the increase in PC12 cell numbers and MTT activity. IH-cultured PC12 cells displayed increased and sustained HIF-1 expression over 96 h. This was accompanied by increased ROS and mitochondrial burden. PC12 cells in CN displayed little changes in HIF-1 expression or ROS levels. DMOG (0.1 mM) supplementation resulted in an IH-like HIF-1 profile. The mitochondrial burden and action potential of DMOG-supplemented PC12 cells did not mirror those seen in other conditions. DMOG significantly increased S phase cell populations after 72 and 96 h. No significant effect on PC12 cell differentiation was noted with IH and CN culture without induction by nerve growth factor (NGF), while DMOG significantly increased PC12 cell differentiation with and without NGF. In conclusion, DMOG and reduced oxygen levels stabilise HIF and affect mitochondrial activity and cell behaviour. However, DMOG does not provide an accurate replication of the reduced oxygen environments.

High glucose inhibits the osteogenic differentiation of periodontal ligament stem cells in periodontitis by activating endoplasmic reticulum stress

Background

Periodontitis is a highly prevalent dental disease which is associated with diabetes and is challenging to cure in diabetic patients. However, the mechanism of comorbid diabetes and periodontitis is still unclear. This study aimed to uncover the role of endoplasmic reticulum (ER) stress in high glucose-associated periodontitis.

Methods

Periodontal tissues were obtained from diabetic patients with periodontitis, periodontitis patients without systemic disease, and healthy teeth. The expressions of ER stress-related factors GRP78, ATF6, PERK and XBP1 were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and immumohistochemical staining. Periodontal ligament stem cells (PDLSCs) from three states of periodontal tissues were isolated and cultured as diabetic PDLSCs (dPDLSCs), inflamed PDLSCs (iPDLSCs) and healthy PDLSCs (hPDLSCs), and the cell stemness was assayed. Different concentrations (8, 11, and 25 mmol/L) of D-glucose were used on hPDLSCs to simulate high glucose microenvironment. The changes of osteogenic ability of PDLSCs were observed, and the expressions of ER stress-related factors in different time point (6, 12, 24, and 72 h) were detected. Finally, GRP78 shRNA lentivirus was used to block ER stress on PDLSCs in the 25 mmol/L D-glucose microenvironment, and the osteogenic ability of PDLSCs was observed.

Results

The results showed that the expressions of GRP78, ATF6, PERK, and XBP1 were highest in the diabetic periodontitis group and lowest in the healthy periodontal tissue group (P<0.05). The clone formation, osteogenic and lipogenic differentiation abilities were lowest in dPDLSCs and highest in hPDLSCs. With the increase of glucose concentration, the osteogensis ability of PDLSCs decreased. After 6 hours of stimulation with D-glucose 25 mmol/L, the ER stress pathways in PDLSCs were effectively activated, and the peak value was reached at 12 hours. The decrease in the osteogensis ability of PDLSCs in a high glucose microenvironment reversed when ER stress was blocked.

Conclusions

The osteogenic differentiation ability of PDLSCs cells is inhibited in a high glucose microenvironment, and this effect is realized by ER stress activation. Blocking ER stress can partially restore the reduced osteogenic ability of PDLSCs. These results suggest that high glucose inhibits the osteogenic differentiation ability of PDLSCs by activating ER stress, which ultimately exacerbates periodontitis.

Endoplasmic reticulum stress contributes to the decline in doublecortin expression in the immature neurons of mice with long-term obesity

Adult hippocampal neurogenesis (AHN) plays an important role in hippocampus-dependent function. The number of doublecortin (Dcx)-positive immature neurons in the dentate gyrus decreases over time, especially in the early stages of Alzheimer’s disease (AD), and is further reduced in later stages of AD. Obesity in midlife is associated with dementia later in life; however, the underlying mechanisms by which obesity results in the development of dementia later in life remain unknown. Here, we show that endoplasmic reticulum (ER) stress was activated in the hippocampus and processes of Dcx-expressing immature neurons were shortened, coexpressing CHOP in APP23 AD model mice with high-fat diet-induced long-term obesity and in aged Lepr^db/db (db/db) mice. Moreover, in cells differentiating from hippocampal neurospheres, Dcx mRNA was rapidly degraded via a microRNA (miRNA) pathway after thapsigargin treatment in vitro. These results indicate that loss of Dcx mRNA induced by ER stress during AHN may cause memory impairment in obese individuals later in life.

Type 2 Diabetic Mellitus Inhibits Skin Renewal through Inhibiting WNT-Dependent Lgr5+ Hair Follicle Stem Cell Activation in C57BL/6 Mice

BACKGROUND

Hair follicles are important accessory organs of the skin, and it is important for skin renewal and performs variety of important functions. Diabetes can cause several dermatoses; however, its effect on hair follicles is unclear. The purpose of this study was to investigate the effect of type II diabetes (T2DM) on the hair follicles of mice.

METHODS

Seven-week-old male C57BL/6 littermate mice were divided into two groups. The treatment group was injected with streptozotocin (STZ) to induce T2DM, and the control group was parallelly injected with the same dose of buffer. Seven days after injection, the back is depilated to observe the hair follicle regeneration. Hair follicle regeneration was observed by naked eyes and HE staining. The proliferation of the skin cells was observed by PCNA and K14 staining. The altered genes were screened by RNA sequencing and verified by qRT-PCR. In addition, Lgr5 + GFP/mTmG transgenic mice were used to observe the effect of T2DM on Lgr5 hair follicle stem cells (HFSC). And the expression of WNT4 and WNT8A were measured by Western Blot.

RESULTS

T2DM inhibited hair follicle regeneration. Compared to control mice, T2DM mice had smaller hair follicles, reduced skin thickness, and less expression of PCNA and K14. RNA sequencing showed that the two groups had significant differences in cell cycle and proliferation-related pathways. Compared with the control mice, the mRNA expression of Lgr4, Lgr5, Wnt4, and Wnt8a was decreased in the T2DM group. Moreover, T2DM inhibited the activation of Lgr5 HFSC and the expression of WNT4 and WNT8A.

CONCLUSIONS

T2DM inhibited hair follicle regeneration and skin cells proliferation by inhibiting WNT-dependent Lgr5 HFSC activation. This may be an important reason for the reduction of skin renewal ability and the formation of chronic wounds caused by diabetes. It is important for the treatment of chronic diabetic wounds and the development of tissue engineering.

Nutrients in the fate of pluripotent stem cells

Pluripotent stem cells model certain features of early mammalian development ex vivo. Medium-supplied nutrients can influence self-renewal, lineage specification, and earliest differentiation of pluripotent stem cells. However, which specific nutrients support these distinct outcomes, and their mechanisms of action, remain under active investigation. Here, we evaluate the available data on nutrients and their metabolic conversion that influence pluripotent stem cell fates. We also discuss key questions open for investigation in this rapidly expanding area of increasing fundamental and practical importance.

ER-Phagy: A New Regulator of ER Homeostasis

The endoplasmic reticulum (ER) is one of the most important cellular organelles and is essential for cell homeostasis. Upon external stimulation, ER stress induces the unfolded protein response (UPR) and ER-associated degradation (ERAD) to maintain ER homeostasis. However, persistent ER stress can lead to cell damage. ER-phagy is a selective form of autophagy that ensures the timely removal of damaged ER, thereby protecting cells from damage caused by excessive ER stress. As ER-phagy is a newly identified form of autophagy, many receptor-mediated ER-phagy pathways have been discovered in recent years. In this review, we summarize our understanding of the maintenance of ER homeostasis and describe the receptors identified to date. Finally, the relationships between ER-phagy and diseases are also discussed.

Protective role and molecular mechanism of action of Nesfatin-1 against high glucose-induced inflammation, oxidative stress and apoptosis in retinal epithelial cells

Diabetic retinopathy (DR) is a major complication of diabetes mellitus that may cause severe visual impairment. It has been reported that the levels of nesfatin-1 in the serum and vitreous humor were negatively correlated with DR; however, its role in DR has not been fully elucidated. Therefore, the present study was performed to investigate the effect of nesfatin-1 on high glucose-treated human retinal epithelial cells (ARPE-19) and explore the underlying mechanism. The effects of nesfatin-1 on cell viability, inflammation, oxidative stress and apoptosis were examined under high glucose conditions. The Cell Counting Kit-8 assay was used to determine cell viability. The levels of inflammatory cytokines were evaluated using ELISA kits. The reactive oxygen species and malondialdehyde content was estimated using commercial assay kits. Flow cytometry was performed to detect apoptotic cells and western blot analysis was employed to evaluate the expression of apoptosis-associated proteins. Moreover, the levels of NF-κB, NACHT, LRR and PYD domains-containing protein 3 (NLRP3) and high-mobility group protein B1 (HMGB1) were determined via western blot analysis. The results revealed that nesfatin-1 enhanced cell viability and suppressed inflammation, oxidative stress and apoptosis in the presence of high glucose concentration. Moreover, the activation of the NF-κB/NLRP3 inflammasome signaling and the expression of HMGB1 were inhibited by nesfatin-1. Furthermore, HMGB1 overexpression partially abrogated the inactivation of the NF-κB/NLRP3 inflammasome pathway caused by nesfatin-1. Taken together, these findings demonstrated that nesfatin-1 inhibited the activation of the NF-κB/NLRP3 inflammasome signaling via modulating HMGB1 and exerted a protective effect on ARPE-19 cells against high glucose-induced inflammation, oxidative stress and apoptosis.

Neural differentiation medium for human pluripotent stem cells to model physiological glucose levels in human brain

Cortical neurospheres (NSPs) derived from human pluripotent stem cells (hPSC), have proven to be a successful platform to investigate human brain development and neuro-related diseases. Currently, many of the standard hPSC neural differentiation media, use concentrations of glucose (approximately 17.5-25 mM) and insulin (approximately 3.2 μM) that are much greater than the physiological concentrations found in the human brain. These culture conditions make it difficult to analyse perturbations of glucose or insulin on neuronal development and differentiation. We established a new hPSC neural differentiation medium that incorporated physiological brain concentrations of glucose (2.5 mM) and significantly reduced insulin levels (0.86 μM). This medium supported hPSC neural induction and formation of cortical NSPs. The revised hPSC neural differentiation medium, may provide an improved platform to model brain development and to investigate neural differentiation signalling pathways impacted by abnormal glucose and insulin levels.

The Role of Non-coding RNAs in Diabetic Nephropathy-Related Oxidative Stress

Diabetic nephropathy (DN) is one of the main complications of diabetes and the main cause of diabetic end-stage renal disease, which is often fatal. DN is usually characterized by progressive renal interstitial fibrosis, which is closely related to the excessive accumulation of extracellular matrix and oxidative stress. Non-coding RNAs (ncRNAs) are RNA molecules expressed in eukaryotic cells that are not translated into proteins. They are widely involved in the regulation of biological processes, such as, chromatin remodeling, transcription, post-transcriptional modification, and signal transduction. Recent studies have shown that ncRNAs play an important role in the occurrence and development of DN and participate in the regulation of oxidative stress in DN. This review clarifies the functions and mechanisms of ncRNAs in DN-related oxidative stress, providing valuable insights into the prevention, early diagnosis, and molecular therapeutic targets of DN.

Transcriptome sequencing reveals genes involved in cadmium-triggered oxidative stress in the chicken heart

As a ubiquitous heavy metal, cadmium (Cd) is highly toxic to various organs. However, the effects and molecular mechanism of Cd toxicity in the chicken heart remain largely unknown. The goal of our study was to investigate the cardiac injury in chickens' exposure to Cd. We detected the levels of oxidative stress-related molecules in the Cd-induced chicken heart, and assessed the histopathological changes by hematoxylin and eosin staining. RNA sequencing was performed to identify differentially expressed mRNAs between the Cd-induced group and control group. The expression of candidate genes involved in oxidative stress was certified by quantitative reverse transcription PCR. Our results showed that the expression of glutathione, peroxidase, and superoxide dismutase was significantly decreased and malondialdehyde was increased in the heart of chickens by Cd induction. The disorderly arranged cardiomyocytes, swelled and enlarged cells, partial cardiomyocyte necrosis, blurred morphological structure, and notable inflammatory cell infiltration were observed in the Cd-induced chicken heart. RNA sequencing identified 23 upregulated and 11 downregulated mRNAs in the heart tissues of the chicken in the Cd-induced group, and functional pathways indicated that they were associated with oxidative stress. Moreover, CREM, DUSP8, and ITGA11 expressions were significantly reduced, whereas LAMA1 expression was induced in heart tissue of chickens by Cd treatment. Overall, our findings revealed that oxidative stress and pathological changes in the chicken heart could be triggered by Cd. The mRNA transcriptional profiles identified differentially expressed genes in the chicken heart by Cd induction, revealing oxidative stress-related key genes and enhancing our understanding of Cd toxicity in the chicken heart.

The role of Nrf2 in neural stem/progenitors cells: From maintaining stemness and self-renewal to promoting differentiation capability and facilitating therapeutic application in neurodegenerative disease

Neurodegenerative diseases (NDs) cause progressive loss of neurons in nervous system. NDs are categorized as acute NDs such as stroke and head injury, besides chronic NDs including Alzheimer's, Parkinson's, Huntington's diseases, Friedreich's Ataxia, Multiple Sclerosis. The exact etiology of NDs is not understood but oxidative stress, inflammation and synaptic dysfunction are main hallmarks. Oxidative stress leads to free radical attack on neural cells which contributes to protein misfolding, glia cell activation, mitochondrial dysfunction, impairment of DNA repair system and subsequently cellular death. Neural stem cells (NSCs) support adult neurogenesis in nervous system during injuries which is limited to certain regions in brain. NSCs can differentiate into the neurons, astrocytes or oligodendrocytes. Impaired neurogenesis and inadequate induction of neurogenesis are the main obstacles in treatment of NDs. Protection of neural cells from oxidative damages and supporting neurogenesis are promising strategies to treat NDs. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a transcriptional master regulator that maintains the redox homeostasis in cells by provoking expression of antioxidant, anti-inflammatory and cytoprotective genes. Nrf2 can strongly influence the NSCs function and fate determination by reducing levels of reactive oxygen species in benefit of NSC survival and neurogenesis. In this review we will summarize the role of Nrf2 in NSC function, and exogenous and endogenous therapeutic strategies in treatment of NDs.

Therapeutic Potential of Reactive Oxygen Species: State of the Art and Recent Advances

In the last decade, several studies have proven that when at low concentration reactive oxygen species (ROS) show an adaptive beneficial effect and posited the idea that they can be utilized as inexpensive and convenient inducers of tissue regeneration. On the other hand, the recent discovery that cancer cells are more sensitive to oxidative damage paved the way for their use in the selective killing of tumor cells, and sensors to monitor ROS production during cancer treatment are under extensive investigation. Nevertheless, although ROS-activated signaling pathways are well established, less is known about the mechanisms underlying the switch from an anabolic to a cytotoxic response. Furthermore, a high variability in biological response is observed between different modalities of administration, cell types, donor ages, eventual concomitant diseases, and external microenvironment. On the other hand, available preclinical studies are scarce, whereas the quest for the most suitable systems for in vivo delivery is still elusive. Furthermore, new strategies to control the temporal pattern of ROS release need to be developed, if considering their tumorigenic potential. This review initially discusses ROS mechanisms of action and their potential application in stem cell biology, tissue engineering, and cancer therapy. It then outlines the state of art of ROS-based drugs and identifies challenges faced in translating ROS research into clinical practice.

Entacapone Treatment Modulates Hippocampal Proteins Related to Synaptic Vehicle Trafficking

Entacapone, a reversible inhibitor of catechol-O-methyl transferase, is used for patients in Parkinson’s disease because it increases the bioavailability and effectiveness of levodopa. In the present study, we observed that entacapone increases novel object recognition and neuroblasts in the hippocampus. In the present study, two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were performed to compare the abundance profiles of proteins expressed in the hippocampus after entacapone treatment in mice. Results of 2-DE, MALDI-TOF mass spectrometry, and subsequent proteomic analysis revealed an altered protein expression profile in the hippocampus after entacapone treatment. Based on proteomic analysis, 556 spots were paired during the image analysis of 2-DE gels and 76 proteins were significantly changed more than two-fold among identified proteins. Proteomic analysis indicated that treatment with entacapone induced expressional changes in proteins involved in synaptic transmission, cellular processes, cellular signaling, the regulation of cytoskeletal structure, energy metabolism, and various subcellular enzymatic reactions. In particular, entacapone significantly increased proteins related to synaptic trafficking and plasticity, such as dynamin 1, synapsin I, and Munc18-1. Immunohistochemical staining showed the localization of the proteins, and western blot confirmed the significant increases in dynamin I (203.5% of control) in the hippocampus as well as synapsin I (254.0% of control) and Munc18-1 (167.1% of control) in the synaptic vesicle fraction of hippocampus after entacapone treatment. These results suggest that entacapone can enhance hippocampal synaptic trafficking and plasticity against various neurological diseases related to hippocampal dysfunction.

Flexible Electronics for Monitoring in vivo Electrophysiology and Metabolite Signals

Numerous efforts have been made to develop efficient biosensors for detecting analytes in the human body. However, biosensors are often developed on rigid materials, which limits their application on skin, organs, and other tissues in the human body where good flexibility is required. Developing flexible materials for biosensors that can be used on soft and irregularly shaped surfaces would significantly expand the clinical application of biosensors. In this review, we will provide a selective overview of recently developed flexible electronic devices and their applications for monitoring in vivo metabolite and electrophysiology signals. The article provides guidelines for the development of an in vivo signal monitoring system and emphasizes research from various disciplines for the further development of flexible electronics that can be used in more biomedical applications in the future.

Patient-Derived Midbrain Organoids to Explore the Molecular Basis of Parkinson's Disease

Induced pluripotent stem cell-derived organoids offer an unprecedented access to complex human tissues that recapitulate features of architecture, composition and function of in vivo organs. In the context of Parkinson's Disease (PD), human midbrain organoids (hMO) are of significant interest, as they generate dopaminergic neurons expressing markers of Substantia Nigra identity, which are the most vulnerable to degeneration. Combined with genome editing approaches, hMO may thus constitute a valuable tool to dissect the genetic makeup of PD by revealing the effects of risk variants on pathological mechanisms in a representative cellular environment. Furthermore, the flexibility of organoid co-culture approaches may also enable the study of neuroinflammatory and neurovascular processes, as well as interactions with other brain regions that are also affected over the course of the disease. We here review existing protocols to generate hMO, how they have been used so far to model PD, address challenges inherent to organoid cultures, and discuss applicable strategies to dissect the molecular pathophysiology of the disease. Taken together, the research suggests that this technology represents a promising alternative to 2D in vitro models, which could significantly improve our understanding of PD and help accelerate therapeutic developments.

The Reciprocal Causation of the ASK1-JNK1/2 Pathway and Endoplasmic Reticulum Stress in Diabetes-Induced Cognitive Decline

Diabetes significantly induces cognitive dysfunction. Neuronal apoptosis is the main cause of diabetes-induced cognitive decline (DICD). Apoptosis signal-regulating kinase 1 (ASK1) and endoplasmic reticulum (ER) stress are remarkably activated by diabetes. The role and relationship of ASK1-JNK1/2 signaling and ER stress in DICD have not yet been elucidated. In this study, we used db/db mice as the DICD animal model and confirmed that db/db mice displayed cognitive decline with inferior learning and memory function. Diabetes significantly induced morphological and structural changes, excessive neuronal apoptosis, Aβ_{1 - 42} large deposition, and synaptic dysfunction in the hippocampus. Mechanistic studies found that diabetes significantly triggered ASK1-JNK1/2 signaling activation and increased ER stress in the hippocampus. Moreover, diabetes enhanced the formation of the IRE1α-TRAF2-ASK1 complex, which promotes the crosstalk of ER stress and the ASK1-JNK1/2 pathway during DICD. Furthermore, 4-PBA treatment blocked high glucose (HG)-induced ASK1-JNK1/2 signaling activation, and excessive apoptosis in vitro. Inhibiting ASK1 via siRNA remarkably ameliorated the HG-induced increase in p-IRE1α and associated apoptosis in SH-SY5Y cells, suggesting that ASK1 is essential for the assembly and function of the proapoptotic kinase activity of the IRE1α signalosome. In summary, ER stress and ASK1-JNK1/2 signaling play causal roles in DICD development, which has crosstalk through the formation of the IRE1α-TRAF2-ASK1 complex.

Overexpression of cortistatin alleviates oxygen/glucose-deprivation-induced ER stress and prompts neural stem cell proliferation via SSTR2

Cerebral infarction (CI), a blood circulatory disorder, causes a high mortality and disability rate worldwide. Intriguingly, a newly discovered neuropeptide, Cortistatin (CST), has been indicated to inhibit the cortical activity. In our research, we aimed to explore the functional relevance of CST in neural stem cells (NSCs) in CI rats. The expression of CST was determined in NSCs induced by oxygen-glucose deprivation (OGD). NSCs isolated from the embryonic rat brain were treated with OGD to establish an in vitro CI model while dithiothreitol (DTT) was introduced to induce endoplasmic reticulum stress (ERS), which were evaluated by assessment of GRP94, caspase-12 and CHOP expression. Then CST expression was restored by transfection of oe-CST, followed by assessment of NSC proliferation ability and cytotoxicity. Finally, the expression of CST and its receptor Somatostatin receptor subtype 2 (SSTR2) was quantified for mechanism exploration. CST was downregulated in CI, which was further confirmed in NSCs under OGD treatment. Overexpressed CST was found to promote cell activity and attenuate OGD-induced cytotoxicity of NSCs. Meanwhile, it was observed that the injured proliferation ability of NSCs was restored by CST overexpression. Besides, lower expression of GRP94, caspase-12 and CHOP was indicative of suppressed occurrence of ERS by CST. Mechanically, CST inhibited ERS through SSTR2. CST could facilitate the proliferation of NSCs in CI induced by OGD, ultimately highlighting a novel therapeutic target for CI treatment.

Nutrients and neurogenesis: the emerging role of autophagy and gut microbiota

Adult neurogenesis, the generation of mature functional neurons from neural stem cells in specific regions of the adult mammalian brain, is implicated in brain physiology, neurodegeneration and mood disorders. Among the many intrinsic and extrinsic factors that modulate neurogenic activity, the role of nutrients, energy metabolism, and gut microbiota has recently emerged. It is increasingly evident that excessive calorie intake accelerates the age-dependent decline of neurogenesis, while calorie restriction and physical exercise have the opposite effect. Mechanistically, nutrient availability could affect neurogenesis by modulating autophagy, a cell-rejuvenating process, in neural stem cells. In parallel, diet can alter the composition of gut microbiota thus impacting the intestine-neurogenic niche communication. These exciting breakthroughs are here concisely reviewed.

The Role of Mitochondrial and Endoplasmic Reticulum Reactive Oxygen Species Production in Models of Perinatal Brain Injury

Significance: Perinatal brain injury is caused by hypoxia-ischemia (HI) in term neonates, perinatal arterial stroke, and infection/inflammation leading to devastating long-term neurodevelopmental deficits. Therapeutic hypothermia is the only currently available treatment but is not successful in more than 50% of term neonates suffering from hypoxic-ischemic encephalopathy. Thus, there is an urgent unmet need for alternative or adjunct therapies. Reactive oxygen species (ROS) are important for physiological signaling, however, their overproduction/accumulation from mitochondria and endoplasmic reticulum (ER) during HI aggravate cell death. Recent Advances and Critical Issues: Mechanisms underlying ER stress-associated ROS production have been primarily elucidated using either non-neuronal cells or adult neurodegenerative experimental models. Findings from mature brain cannot be simply transferred to the immature brain. Therefore, age-specific studies investigating ER stress modulators may help investigate ER stress-associated ROS pathways in the immature brain. New therapeutics such as mitochondrial site-specific ROS inhibitors that selectively inhibit superoxide (O2•-)/hydrogen peroxide (H2O2) production are currently being developed. Future Directions: Because ER stress and oxidative stress accentuate each other, a combinatorial therapy utilizing both antioxidants and ER stress inhibitors may prove to be more protective against perinatal brain injury. Moreover, multiple relevant targets need to be identified for targeting ROS before they are formed. The role of organelle-specific ROS in brain repair needs investigation. Antioxid. Redox Signal. 31, 643-663.

Endoplasmic Reticulum Stress Activated by Androgen Enhances Apoptosis of Granulosa Cells via Induction of Death Receptor 5 in PCOS

Polycystic ovary syndrome (PCOS) is associated with hyperandrogenism and growth arrest of antral follicles. Previously, we found that endoplasmic reticulum (ER) stress is activated in granulosa cells of antral follicles in PCOS, evidenced by activation of unfolded protein response (UPR) genes. Based on this observation, we hypothesized that ER stress is activated by androgens in granulosa cells of antral follicles, and that activated ER stress promotes apoptosis via induction of the UPR transcription factor C/EBP homologous protein (CHOP) and subsequent activation of death receptor (DR) 5. In this study, we found that testosterone induced expression of various UPR genes, including CHOP, as well as DR5, in cultured human granulosa-lutein cells (GLCs). Pretreatment with the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) inhibited testosterone-induced apoptosis and expression of DR5 and CHOP. Knockdown of CHOP inhibited testosterone-induced DR5 expression and apoptosis, and knockdown of DR5 inhibited testosterone-induced apoptosis. Pretreatment with flutamide, as well as knockdown of androgen receptor, decreased testosterone-induced DR5 and CHOP expression, as well as apoptosis. Expression of DR5 and CHOP was upregulated in GLCs obtained from patients with PCOS, as well as in granulosa cells of antral follicles in ovarian sections obtained from patients with PCOS and dehydroepiandrosterone-induced PCOS mice. Treatment of PCOS mice with TUDCA decreased apoptosis and DR5 expression in granulosa cells of antral follicles, with a concomitant reduction in CHOP expression. Taken together, our findings indicate that ER stress activated by hyperandrogenism in PCOS promotes apoptosis of granulosa cells of antral follicles via induction of DR5.