Substance P Reduces Infarct Size and Mortality After Ischemic Stroke, Possibly Through the M2 Polarization of Microglia/Macrophages and Neuroprotection in the Ischemic Rat Brain.

Substance-P (SP) is an 11 amino acid neuropeptide that is known to stimulate the peripheral mobilization of bone marrow mesenchymal stem cells and M2 polarization in monocytes/macrophages in a variety of acute and chronic tissue injuries. To examine the role of SP in protection and recovery from acute ischemic brain injury, experimental ischemic stroke was induced by transient middle cerebral artery occlusion (tMCAo) in rats for 1 h with subsequent reperfusion. Two injections of SP, immediately and one day post-tMCAo, resulted in approximately threefold lower mortality and 40% less infarct volume than those of saline-treated rats at seven days post-tMCAo. At 4.5 h, SP markedly increased CD11b/c+CD163+/CD 206+ cells in the blood, which were concomitantly decreased in the bone marrow, suggesting that SP preferentially mobilized M2-polarized monocytes. After two days, SP increased the expression of neuroprotective and anti-inflammatory genes in the ischemic brain and induced neuronal survival in the brain penumbra. Additionally, SP markedly increased CD68+CD163+ and CD68+CD206+ M2 microglia/macrophages in the ischemic brain during seven days post-tMCAo. Furthermore, SP preserved the blood‒brain barrier in the ischemic brain, which was confirmed by the abundant levels of SMI71+ brain endothelial cells that colocalized with α-SMA+ pericytes. The beneficial effects of SP on functional recovery and tissue preservation were maintained for six weeks. Collectively, SP treatment in the early phase of ischemic stroke markedly suppressed the destructive inflammatory response and improved the microenvironment for tissue protection and repair.

PTBP1 as a potential regulator of disease.

Polypyrimidine tract-binding protein 1 (PTBP1) is a member of the heterogeneous nuclear ribonucleoprotein (hnRNP) family, which plays a key role in alternative splicing of precursor mRNA and RNA metabolism. PTBP1 is universally expressed in various tissues and binds to multiple downstream transcripts to interfere with physiological and pathological processes such as the tumor growth, body metabolism, cardiovascular homeostasis, and central nervous system damage, showing great prospects in many fields. The function of PTBP1 involves the regulation and interaction of various upstream molecules, including circular RNAs (circRNAs), microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). These regulatory systems are inseparable from the development and treatment of diseases. Here, we review the latest knowledge regarding the structure and molecular functions of PTBP1 and summarize its functions and mechanisms of PTBP1 in various diseases, including controversial studies. Furthermore, we recommend future studies on PTBP1 and discuss the prospects of targeting PTBP1 in new clinical therapeutic approaches.

TAX1BP1 contributes to deoxypodophyllotoxin-induced glioma cell parthanatos via inducing nuclear translocation of AIF by activation of mitochondrial respiratory chain complex I.

Parthanatos is a type of programmed cell death initiated by over-activated poly (ADP-ribose) polymerase 1 (PARP1). Nuclear translocation of apoptosis inducing factor (AIF) is a prominent feature of parthanatos. But it remains unclear how activated nuclear PARP1 induces mitochondrial AIF translocation into nuclei. Evidence has shown that deoxypodophyllotoxin (DPT) induces parthanatos in glioma cells via induction of excessive ROS. In this study we explored the downstream signal of activated PARP1 to induce nuclear translocation of AIF in DPT-triggered glioma cell parthanatos. We showed that treatment with DPT (450 nM) induced PARP1 over-activation and Tax1 binding protein 1 (TAX1BP1) distribution to mitochondria in human U87, U251 and U118 glioma cells. PARP1 activation promoted TAX1BP1 distribution to mitochondria by depleting nicotinamide adenine dinucleotide (NAD+). Knockdown of TAX1BP1 with siRNA not only inhibited TAX1BP1 accumulation in mitochondria, but also alleviated nuclear translocation of AIF and glioma cell death. We demonstrated that TAX1BP1 enhanced the activity of respiratory chain complex I not only by upregulating the expression of ND1, ND2, NDUFS2 and NDUFS4, but also promoting their assemblies into complex I. The activated respiratory complex I generated more superoxide to cause mitochondrial depolarization and nuclear translocation of AIF, while the increased mitochondrial superoxide reversely reinforced PARP1 activation by inducing ROS-dependent DNA double strand breaks. In mice bearing human U87 tumor xenograft, administration of DPT (10 mg· kg-1 ·d-1, i.p., for 8 days) markedly inhibited the tumor growth accompanied by NAD+ depletion, TAX1BP1 distribution to mitochondria, AIF distribution to nuclei as well as DNA DSBs and PARP1 activation in tumor tissues. Taken together, these data suggest that TAX1BP1 acts as a downstream signal of activated PARP1 to trigger nuclear translocation of AIF by activation of mitochondrial respiratory chain complex I.

Activated SIRT1 contributes to DPT-induced glioma cell parthanatos by upregulation of NOX2 and NAT10.

Parthanatos is a type of programmed cell death dependent on hyper-activation of poly (ADP-ribose) polymerase 1 (PARP-1). SIRT1 is a highly conserved nuclear deacetylase and often acts as an inhibitor of parthanatos by deacetylation of PARP1. Our previous study showed that deoxypodophyllotoxin (DPT), a natural compound isolated from the traditional herb Anthriscus sylvestris, triggered glioma cell death via parthanatos. In this study, we investigated the role of SIRT1 in DPT-induced human glioma cell parthanatos. We showed that DPT (450 nmol/L) activated both PARP1 and SIRT1, and induced parthanatos in U87 and U251 glioma cells. Activation of SIRT1 with SRT2183 (10 µmol/L) enhanced, while inhibition of SIRT1 with EX527 (200 µmol/L) or knockdown of SIRT1 attenuated DPT-induced PARP1 activation and glioma cell death. We demonstrated that DPT (450 nmol/L) significantly decreased intracellular NAD+ levels in U87 and U251 cells. Further decrease of NAD+ levels with FK866 (100 µmol/L) aggravated, but supplement of NAD+ (0.5, 2 mmol/L) attenuated DPT-induced PARP1 activation. We found that NAD+ depletion enhanced PARP1 activation via two ways: one was aggravating ROS-dependent DNA DSBs by upregulation of NADPH oxidase 2 (NOX2); the other was reinforcing PARP1 acetylation via increase of N-acetyltransferase 10 (NAT10) expression. We found that SIRT1 activity was improved when being phosphorylated by JNK at Ser27, the activated SIRT1 in reverse aggravated JNK activation via upregulating ROS-related ASK1 signaling, thus forming a positive feedback between JNK and SIRT1. Taken together, SIRT1 activated by JNK contributed to DPT-induced human glioma cell parthanatos via initiation of NAD+ depletion-dependent upregulation of NOX2 and NAT10.

Erratum: Trehalose inhibits H2O2-induced autophagic death in dopaminergic SH-SY5Y cells via mitigation of ROS-dependent endoplasmic reticulum stress and AMPK activation: Erratum.

[This corrects the article DOI: 10.7150/ijms.25656.].

Lactate attenuates astrocytic inflammation by inhibiting ubiquitination and degradation of NDRG2 under oxygen-glucose deprivation conditions.

BACKGROUND: Brain lactate concentrations are enhanced in response to cerebral ischemia and promote the formation of reactive astrocytes, which are major components of the neuroinflammatory response and functional recovery, following cerebral ischemia. NDRG2 is upregulated during reactive astrocyte formation. However, its regulation and function are unclear. We studied the relationship between lactate and NDRG2 in astrocytes under conditions of ischemia or oxygen-glucose deprivation (OGD). METHODS: We examined astrocytic NDRG2 expression after middle cerebral artery occlusion (MCAO) using western blot and immunofluorescence staining. Under hypoxia conditions, we added exogenous L-lactate sodium (lactate) to cultured primary astrocytes to explore the effects of lactate on the ubiquitination modification of NDRG2. We profiled the transcriptomic features of NDRG2 silencing in astrocytes after 8 h of OGD conditions as well as exogenous lactate treatment by performing RNA-seq. Finally, we evaluated the molecular mechanisms of NDRG2 in regulating TNFα under OGD conditions using western blot and immunohistochemistry. RESULTS: Reactive astrocytes strongly expressed NDRG2 in a rat model of MCAO. We also showed that lactate stabilizes astrocytic NDRG2 by inhibiting its ubiquitination. NDRG2 inhibition in astrocytes increased inflammation and upregulated immune-associated genes and signaling pathways. NDRG2 knockdown induced TNFα expression and secretion via c-Jun phosphorylation. CONCLUSIONS: We revealed that under OGD conditions, lactate plays an important anti-inflammatory role and inhibits TNFα expression by stabilizing NDRG2, which is beneficial for neurological functional recovery. NDRG2 may be a new therapeutic target for cerebral ischemia.

miR-124: A Promising Therapeutic Target for Central Nervous System Injuries and Diseases.

Central nervous system injuries and diseases, such as ischemic stroke, spinal cord injury, neurodegenerative diseases, glioblastoma, multiple sclerosis, and the resulting neuroinflammation often lead to death or long-term disability. MicroRNAs are small, non-coding, single-stranded RNAs that regulate posttranscriptional gene expression in both physiological and pathological cellular processes, including central nervous system injuries and disorders. Studies on miR-124, one of the most abundant microRNAs in the central nervous system, have shown that its dysregulation is related to the occurrence and development of pathology within the central nervous system. Herein, we review the molecular regulatory functions, underlying mechanisms, and effective delivery methods of miR-124 in the central nervous system, where it is involved in pathological conditions. The review also provides novel insights into the therapeutic target potential of miR-124 in the treatment of human central nervous system injuries or diseases.

The role of exosomal microRNAs in central nervous system diseases.

MicroRNAs (miRNA), endogenous non-coding RNAs approximately 22 nucleotides long, regulate gene expression by mediating translational inhibition or mRNA degradation. Exosomes are a tool for intercellular transmission of information in which miRNA exchange plays an important role. Under pathophysiological conditions in the central nervous system (CNS), cellular transmission of exosomal miRNAs can regulate signaling pathways. Exosomal miRNAs are involved in the occurrence and development of diverse CNS diseases, such as traumatic brain injury, spinal cord injury, stroke, neurodegenerative diseases, epilepsy, and glioma. The use of exosomes as transport vehicles for certain miRNAs provides a novel therapeutic strategy for CNS diseases. Furthermore, the exosomes in body fluids change with the occurrence of diseases, indicating that subtle changes in physiological and pathological processes in vivo could be recognized by analyzing exosomes. Exosomal analysis is expected to act as a novel tool for diagnosis and prediction of neurological diseases. In this review, we present the current understanding of the implications of miRNAs in CNS diseases and summarize the role and mechanism of action of exosomal miRNA in nervous system disease models.

ATF3 contributes to brucine-triggered glioma cell ferroptosis via promotion of hydrogen peroxide and iron.

Ferroptotic cell death is characterized by iron-dependent lipid peroxidation that is initiated by ferrous iron and H2O2 via Fenton reaction, in which the role of activating transcription factor 3 (ATF3) remains elusive. Brucine is a weak alkaline indole alkaloid extracted from the seeds of Strychnos nux-vomica, which has shown potent antitumor activity against various tumors, including glioma. In this study, we showed that brucine inhibited glioma cell growth in vitro and in vivo, which was paralleled by nuclear translocation of ATF3, lipid peroxidation, and increases of iron and H2O2. Furthermore, brucine-induced lipid peroxidation was inhibited or exacerbated when intracellular iron was chelated by deferoxamine (500 µM) or improved by ferric ammonium citrate (500 µM). Suppression of lipid peroxidation with lipophilic antioxidants ferrostatin-1 (50 µM) or liproxstatin-1 (30 µM) rescued brucine-induced glioma cell death. Moreover, knockdown of ATF3 prevented brucine-induced accumulation of iron and H2O2 and glioma cell death. We revealed that brucine induced ATF3 upregulation and translocation into nuclei via activation of ER stress. ATF3 promoted brucine-induced H2O2 accumulation via upregulating NOX4 and SOD1 to generate H2O2 on one hand, and downregulating catalase and xCT to prevent H2O2 degradation on the other hand. H2O2 then contributed to brucine-triggered iron increase and transferrin receptor upregulation, as well as lipid peroxidation. This was further verified by treating glioma cells with exogenous H2O2 alone. Moreover, H2O2 reversely exacerbated brucine-induced ER stress. Taken together, ATF3 contributes to brucine-induced glioma cell ferroptosis via increasing H2O2 and iron.

FOXO3a protects glioma cells against temozolomide-induced DNA double strand breaks via promotion of BNIP3-mediated mitophagy.

FOXO3a (forkhead box transcription factor 3a) is involved in regulating multiple biological processes in cancer cells. BNIP3 (Bcl-2/adenovirus E1B 19-kDa-interacting protein 3) is a receptor accounting for priming damaged mitochondria for autophagic removal. In this study we investigated the role of FOXO3a in regulating the sensitivity of glioma cells to temozolomide (TMZ) and its relationship with BNIP3-mediated mitophagy. We showed that TMZ dosage-dependently inhibited the viability of human U87, U251, T98G, LN18 and rat C6 glioma cells with IC50 values of 135.75, 128.26, 142.65, 155.73 and 111.60 µM, respectively. In U87 and U251 cells, TMZ (200 µM) induced DNA double strand breaks (DSBs) and nuclear translocation of apoptosis inducing factor (AIF), which was accompanied by BNIP3-mediated mitophagy and FOXO3a accumulation in nucleus. TMZ treatment induced intracellular ROS accumulation in U87 and U251 cells via enhancing mitochondrial superoxide, which not only contributed to DNA DSBs and exacerbated mitochondrial dysfunction, but also upregulated FOXO3a expression. Knockdown of FOXO3a aggravated TMZ-induced DNA DSBs and mitochondrial damage, as well as glioma cell death. TMZ treatment not only upregulated BNIP3 and activated autophagy, but also triggered mitophagy by prompting BNIP3 translocation to mitochondria and reinforcing BNIP3 interaction with LC3BII. Inhibition of mitophagy by knocking down BNIP3 with SiRNA or blocking autophagy with 3MA or bafilomycin A1 exacerbated mitochondrial superoxide and intracellular ROS accumulation. Moreover, FOXO3a knockdown inhibited TMZ-induced BNIP3 upregulation and autophagy activation. In addition, we showed that treatment with TMZ (100 mg·kg-1·d-1, ip) for 12 days in C6 cell xenograft mice markedly inhibited tumor growth accompanied by inducing FOXO3a upregulation, oxidative stress and BNIP3-mediated mitophagy in tumor tissues. These results demonstrate that FOXO3a attenuates temozolomide-induced DNA double strand breaks in human glioma cells via promoting BNIP3-mediated mitophagy.

RSL3 induced autophagic death in glioma cells via causing glycolysis dysfunction.

RSL3 is a type of small molecular compound which can inactivate glutathione peroxidase 4 (GPX4) and induce ferroptosis, but its role in glioma cell death remains unclear. In this study, we found RSL3 inhibited the viabilities of glioma cells and induced glioma cell death in a dose-dependent manner. In vitro studies revealed that RSL3-induced cell death was accompanied with the changes of autophagy-associated protein levels and was alleviated by pretreatment of 3-Methyladenine, bafilomycin A1 and knockdown of ATG5 with siRNA. The ATP and pyruvate content as well as the protein levels of HKII, PFKP, PKM2 were decreased in cells treated by RSL3, indicating that RSL3 induced glycolysis dysfunction in glioma cells. Moreover, supplement of exterior sodium pyruvate, which was a final product of glycolysis, not only inhibited the changes of autophagy-associated protein levels caused by RSL3, but also prevented RSL3-induced cell death. In vivo data suggested that the inhibitory effect of RSL3 on the growth of glioma cells was associated with glycolysis dysfunction and autophagy activation. Taken together, RSL3 induced autophagic cell death in glioma cells via causing glycolysis dysfunction.

Trehalose inhibits H2O2-induced autophagic death in dopaminergic SH-SY5Y cells via mitigation of ROS-dependent endoplasmic reticulum stress and AMPK activation.

Autophagy is a catabolic process to maintain intracellular homeostasis via removal of cytoplasmic macromolecules and damaged cellular organelles through lysosome-mediated degradation. Trehalose is often regarded as an autophagy inducer, but we reported previously that it could prevent ischemic insults-induced autophagic death in neurons. Thus, we further investigated in this study whether trehalose could protect human dopaminergic SH-SY5Y cells against H2O2-induced lethal autophagy. We found pretreatment with trehalose not only prevented H2O2-induced death in SH-SY5Y cells, but also reversed H2O2-induced upregulation of LC3II, Beclin1 and ATG5 and downregulation of p62. Then, we proved that either autophagy inhibitor 3MA or genetic knockdown of ATG5 prevented H2O2-triggered death in SH-SY5Y cells. These indicated that trehalose could inhibit H2O2-induced autophagic death in SH-SY5Y cells. Further, we found that trehalose inhibited H2O2-induced AMPK activation and endoplasmic reticulum (ER) stress. Moreover, inhibition of AMPK activation with compound C or alleviation of ER stress with chemical chaperone 4-PBA obviously attenuated H2O2-induced changes in autophagy-related proteins. Notably, we found that trehalose inhibited H2O2-induced increase of intracellular ROS and reduction in the activities of CAT and SOD. Consistently, our data revealed as well that mitigation of intracellular ROS levels with antioxidant NAC markedly attenuated H2O2-induced AMPK activation and ER stress. Therefore, we demonstrated in this study that trehalose prevented H2O2-induced autophagic death in SH-SY5Y cells via mitigation of ROS-dependent endoplasmic reticulum stress and AMPK activation.

Effects of Matrix Stiffness on the Morphology, Adhesion, Proliferation and Osteogenic Differentiation of Mesenchymal Stem Cells.

BMMSCs have drawn great interest in tissue engineering and regenerative medicine attributable to their multi-lineage differentiation capacity. Increasing evidence has shown that the mechanical stiffness of extracellular matrix is a critical determinant for stem cell behaviors. However, it remains unknown how matrix stiffness influences MSCs commitment with changes in cell morphology, adhesion, proliferation, self-renewal and differentiation. We employed fibronectin coated polyacrylamide hydrogels with variable stiffnesses ranging from 13 to 68 kPa to modulate the mechanical environment of BMMSCs and found that the morphology and adhesion of BMMSCs were highly dependent on mechanical stiffness. Cells became more spread and more adhesive on substrates of higher stiffness. Similarly, the proliferation of BMMSCs increased as stiffness increased. Sox2 expression was lower during 4h to 1 week on the 13-16 kPa and 62-68 kPa, in contrast, it was higher during 4h to 1 week on the 48-53 kPa. Oct4 expression on 13-16 kPa was higher than 48-53 kPa at 4h, and it has no significant differences at other time point among three different stiffness groups. On 62-68 kPa, BMMSCs were able to be induced toward osteogenic phenotype and generated a markedly high level of RUNX2, ALP, and Osteopontin. The cells exhibited a polygonal morphology and larger spreading area. These results suggest that matrix stiffness modulates commitment of BMMSCs. Our findings may eventually aid in the development of novel, effective biomaterials for the applications in tissue engineering.

Shikonin induces glioma cell necroptosis in vitro by ROS overproduction and promoting RIP1/RIP3 necrosome formation.

Necroptosis is a type of programmed necrosis regulated by receptor interacting protein kinase 1 (RIP1) and RIP3. Necroptosis is found to be accompanied by an overproduction of reactive oxygen species (ROS), but the role of ROS in regulation of necroptosis remains elusive. In this study, we investigated how shikonin, a necroptosis inducer for cancer cells, regulated the signaling leading to necroptosis in glinoma cells in vitro. Treatment with shikonin (2-10 µmol/L) dose-dependently triggered necrosis and induced overproduction of intracellular ROS in rat C6 and human SHG-44, U87 and U251 glioma cell lines. Moreover, shikonin treatment dose-dependently upregulated the levels of RIP1 and RIP3 and reinforced their interaction in the glioma cells. Pretreatment with the specific RIP1 inhibitor Nec-1 (100 µmol/L) or the specific RIP3 inhibitor GSK-872 (5 µmol/L) not only prevented shikonin-induced glioma cell necrosis but also significantly mitigated the levels of intracellular ROS and mitochondrial superoxide. Mitigation of ROS with MnTBAP (40 µmol/L), which was a cleaner of mitochondrial superoxide, attenuated shikonin-induced glioma cell necrosis, whereas increasing ROS levels with rotenone, which improved the mitochondrial generation of superoxide, significantly augmented shikonin-caused glioma cell necrosis. Furthermore, pretreatment with MnTBAP prevented the shikonin-induced upregulation of RIP1 and RIP3 expression and their interaction while pretreatment with rotenone reinforced these effects. These findings suggest that ROS is not only an executioner of shikonin-induced glioma cell necrosis but also a regulator of RIP1 and RIP3 expression and necrosome assembly.

Differentiation of hepatocytes from induced pluripotent stem cells derived from human hair follicle mesenchymal stem cells.

Due to the limitations of organ donors and immune rejection in severe liver diseases, stem cell-based therapy presents a promising application for tissue repair and regeneration. As a novel cell source, mesenchymal stem cells separated from human hair follicles (HF-MSCs) are convenient to obtain and have no age limit. To date, the differentiation of HF-MSCs into hepatocytes has not been reported. In this study, we explored whether HF-MSCs and HF-MSC-derived-induced pluripotent stem cells (HF-iPS) could differentiate into hepatocytes in vitro. Flow cytometry, Oil Red O stain and Alizarin Red stain were used to identify the characteristics of HF-MSCs. The expression of liver-specific gene was detected by immunofluorescence and Quantitative Polymerase Chain Reaction. Periodic Acid-Schiff stain, Indocyanine Green stain and Low-Density Lipoprotein stain were performed to evaluate the functions of induced hepatocyte-like cells (HLCs). HF-MSCs were unable to differentiate into HLCs using previously reported procedures for MSCs from other tissues. However, HF-iPS efficiently induced the generation of HLCs that expressed hepatocyte markers and drug metabolism-related genes. HF-iPS can be used as novel and alternative cellular tools for inducing hepatocytes in vitro, simultaneously benefiting from utilizing HF-MSCs as a noninvasive and convenient cell source for reprogramming.

Role of histone modifications in neurogenesis and neurodegenerative disease development.

Progressive neuronal dysfunction and death are key features of neurodegenerative diseases; therefore, promoting neurogenesis in neurodegenerative diseases is crucial. With advancements in proteomics and high-throughput sequencing technology, it has been demonstrated that histone post-transcriptional modifications (PTMs) are often altered during neurogenesis when the brain is affected by disease or external stimuli and that the degree of histone modification is closely associated with the development of neurodegenerative diseases. This review aimed to show the regulatory role of histone modifications in neurogenesis and neurodegenerative diseases by discussing the changing patterns and functional significance of histone modifications, including histone methylation, acetylation, ubiquitination, phosphorylation, and lactylation. Finally, we explored the control of neurogenesis and the development of neurodegenerative diseases by artificially modulating histone modifications.

Reprogramming of astrocytes and glioma cells into neurons for central nervous system repair and glioblastoma therapy.

Central nervous system (CNS) damage is usually irreversible owing to the limited regenerative capability of neurons. Following CNS injury, astrocytes are reactively activated and are the key cells involved in post-injury repair mechanisms. Consequently, research on the reprogramming of reactive astrocytes into neurons could provide new directions for the restoration of neural function after CNS injury and in the promotion of recovery in various neurodegenerative diseases. This review aims to provide an overview of the means through which reactive astrocytes around lesions can be reprogrammed into neurons, to elucidate the intrinsic connection between the two cell types from a neurogenesis perspective, and to summarize what is known about the neurotranscription factors, small-molecule compounds and MicroRNA that play major roles in astrocyte reprogramming. As the malignant proliferation of astrocytes promotes the development of glioblastoma multiforme (GBM), this review also examines the research advances on and the theoretical basis for the reprogramming of GBM cells into neurons and discusses the advantages of such approaches over traditional treatment modalities. This comprehensive review provides new insights into the field of GBM therapy and theoretical insights into the mechanisms of neurological recovery following neurological injury and in GBM treatment.

SIRT1 activated by AROS sensitizes glioma cells to ferroptosis via induction of NAD+ depletion-dependent activation of ATF3.

Ferroptosis is a type of programmed cell death resulting from iron overload-dependent lipid peroxidation, and could be promoted by activating transcription factor 3 (ATF3). SIRT1 is an enzyme accounting for removing acetylated lysine residues from target proteins by consuming NAD+, but its role remains elusive in ferroptosis and activating ATF3. In this study, we found SIRT1 was activated during the process of RSL3-induced glioma cell ferroptosis. Moreover, the glioma cell death was aggravated by SIRT1 activator SRT2183, but suppressed by SIRT inhibitor EX527 or when SIRT1 was silenced with siRNA. These indicated SIRT1 sensitized glioma cells to ferroptosis. Furthermore, we found SIRT1 promoted RSL3-induced expressional upregulation and nuclear translocation of ATF3. Silence of ATF3 with siRNA attenuated RSL3-induced increases of ferrous iron and lipid peroxidation, downregulation of SLC7A11 and GPX4 and depletion of cysteine and GSH. Thus, SIRT1 promoted glioma cell ferroptosis by inducting ATF3 activation. Mechanistically, ATF3 activation was reinforced when RSL3-induced decline of NAD+ was aggravated by FK866 that could inhibit NAD + synthesis via salvage pathway, but suppressed when intracellular NAD+ was maintained at higher level by supplement of exogenous NAD+. Notably, the NAD + decline caused by RSL3 was enhanced when SIRT1 was further activated by SRT2183, but attenuated when SIRT1 activation was inhibited by EX527. These indicated SIRT1 promoted ATF3 activation via consumption of NAD+. Finally, we found RSL3 activated SIRT1 by inducing reactive oxygen species-dependent upregulation of AROS. Together, our study revealed SIRT1 activated by AROS sensitizes glioma cells to ferroptosis via activation of ATF3-dependent inhibition of SLC7A11 and GPX4.

The Dual Role of Astrocyte-Derived Exosomes and Their Contents in the Process of Alzheimer's Disease.

Millions of patients worldwide are affected by Alzheimer's disease (AD), and the number of patients with AD is increasing. However, current treatment can only improve symptoms but cannot cure the disease. Astrocytes, glial cells in the central nervous system, play important roles in support, nutrition, protection, and information transmission in the nervous system. Pathological changes in astrocytes are closely associated with the development and progression of AD. As carriers for material and information exchange between astrocytes and other neural cells, astrocyte-derived exosomes (ADEs) have been widely studied in recent years, and ADE secretion has been shown to be increased in patients with AD and animal models of AD. ADEs contain a variety of substances, including nucleic acids, proteins, and lipids. The contents of ADEs can effectively control oxidative stress and detoxification during the early development of AD, thereby playing positive and negative roles in the occurrence and development of AD. In this review, we elaborate on the functions of ADEs and their components in AD and discuss their applications in AD research and clinical practice.