Autophagic Mechanisms Research Articles

Effects of Monobenzyl ether of hydroquinone on 3T3 mouse fibroblast viability and ultrastructure

ABSTRACT Monobenzyl ether of hydroquinone (MBEH) is a topical depigmentation agent used by vitiligo patients to even the skin tone. We aimed to investigate the effects of MBEH on 3T3 mouse fibroblasts. Fibroblasts were treated with 250 µM, 500 µM, and 750 µM MBEH and vehicle (EtOH:DMSO) for 24 hours. Cell numbers of 250 µM, 500 µM, and 750 µM MBEH treated and vehicle groups decreased significantly compared to control group. TUNEL positive cell rate increased with MBEH concentration. In electron microscopic examination, control and vehicle groups showed active cells features, while mitochondrial swelling and cristae loss were seen in 250 µM MBEH-treated group. In cytoplasm of 500 µM MBEH-treated group, there were many multivesicular bodies and autophagic vacuoles. As an indication of apoptosis, cell membrane blebs and reduction in cell size were observed. In 750 μM MBEH-treated group, cells were completely degenerated. Our findings show that MBEH, which is used as a depigmentation agent to lighten the skin by destroying melanocytes, may also have dose-dependent negative effects on the viability of 3T3 mouse fibroblasts, and these may be mediated through autophagic and apoptotic cell death mechanisms.

An imbalance in autophagy contributes to retinal damage in a rat model of oxygen-induced retinopathy.

In retinopathy of prematurity (ROP), the abnormal retinal neovascularization is often accompanied by retinal neuronal dysfunction. Here, a rat model of oxygen‐induced retinopathy (OIR), which mimics the ROP disease, was used to investigate changes in the expression of key mediators of autophagy and markers of cell death in the rat retina. In addition, rats were treated from birth to postnatal day 14 and 18 with 3‐methyladenine (3‐MA), an inhibitor of autophagy. Immunoblot and immunofluorescence analysis demonstrated that autophagic mechanisms are dysregulated in the retina of OIR rats and indicated a possible correlation between autophagy and necroptosis, but not apoptosis. We found that 3‐MA acts predominantly by reducing autophagic and necroptotic markers in the OIR retinas, having no effects on apoptotic markers. However, 3‐MA does not ameliorate retinal function, which results compromised in this model. Taken together, these results revealed the crucial role of autophagy in retinal cells of OIR rats. Thus, inhibiting autophagy may be viewed as a putative strategy to counteract ROP.

The Role of Autophagy at the Nano/Bio Interface - Underlying Mechanisms and Therapeutic Potential in Cancer

<img src=” https://s3.amazonaws.com/production.scholastica/article/28984/medium/prnano_702021ga.jpg?1633851601”> Autophagy plays an essential role in maintaining cellular homeostasis by responding to certain stressed conditions such as nutrient deprivation, organelle damage, pathogen infection, and exposure to certain nanomaterials. Through deliberate tuning of the physicochemical properties, the fate of nanomaterial-treated cells is subjected to various cellular toxicity, stress responses, and immune responses, some of which involve various autophagic mechanisms. Beginning from the molecular basis of the autophagy machinery, we briefly introduce the major understanding of autophagy in inflammation, immunity, cancer metabolism, and therapy. Different working mechanisms will be discussed to classify the impact of physicochemical characteristics on autophagy induction or inhibition by engineered nanomaterials. From the perspective of autophagy-targeting cancer therapeutics, we will further delineate the advanced nano-formulations for improved drug delivery to impact autophagy in the setting of cancer diseases and designing co-delivery nanomedicine that targets autophagy along with another major cancer pathway to achieve in vivo synergy. Moreover, cancer immunotherapy, aiming at immune cells or checkpoints, is also integrated with autophagy-regulatory components using multiple nano-platforms as an emerging strategy for cancer treatment. Considering the recent breakthroughs of nanotechnology targeting autophagy in cancer cells, antigen-presenting cells, or other cell types within tumor microenvironment by precisely designed nanomedicine may provide additional solutions for cancer treatment through autophagy-dependent metabolic regulation or immune pathways. However, one should closely monitor the extent of autophagy alternation and side effects from certain nanoparticles to avoid severe toxic responses.

PKCλ/ι inhibition activates an ULK2-mediated interferon response to repress tumorigenesis

The interferon (IFN) pathway is critical for cytotoxic Tcell activation, which is central to tumor immunosurveillance and successful immunotherapy. We demonstrate here that PKCλ/ι inactivation results in the hyper-stimulation of the IFN cascade and the enhanced recruitment of CD8+ Tcells that impaired the growth of intestinal tumors. PKCλ/ι directly phosphorylates and represses the activity of ULK2, promoting its degradation through an endosomal microautophagy-driven ubiquitin-dependent mechanism. Loss of PKCλ/ι results in increased levels of enzymatically active ULK2, which, by direct phosphorylation, activates TBK1 to foster the activation of the STING-mediated IFN response. PKCλ/ι inactivation also triggers autophagy, which prevents STING degradation by chaperone-mediated autophagy. Thus, PKCλ/ι is a hub regulating the IFN pathway and three autophagic mechanisms that serve to maintain its homeostatic control. Importantly, single-cell multiplex imaging and bioinformatics analysis demonstrated that low PKCλ/ι levels correlate with enhanced IFN signaling and good prognosis in colorectal cancer patients.

GDF-15 Deficiency Reduces Autophagic Activity in Human Macrophages In Vitro and Decreases p62-Accumulation in Atherosclerotic Lesions in Mice.

(1) Background: Growth differentiation factor-15 (GDF-15) is associated with cardiovascular diseases and autophagy in human macrophages (MΦ). Thus, we are interested in investigating autophagic mechanisms with special respect to the role of GDF-15. (2) Methods: Recombinant (r)GDF-15 and siRNA GDF-15 were used to investigate the effects of GDF-15 on autophagic and lysosomal activity, as well as autophagosome formation by transmission electron microscopy (TEM) in MΦ. To ascertain the effects of GDF-15−/− on the progression of atherosclerotic lesions, we used GDF-15−/−/ApoE−/− and ApoE−/− mice under a cholesterol-enriched diet (CED). Body weight, body mass index (BMI), blood lipid levels and lumen stenosis in the brachiocephalic trunk (BT) were analyzed. Identification of different cell types and localization of autophagy-relevant proteins in atherosclerotic plaques were performed by immunofluorescence. (3) Results: siGDF-15 reduced and, conversely, rGDF-15 increased the autophagic activity in MΦ, whereas lysosomal activity was unaffected. Autophagic degradation after starvation and rGDF-15 treatment was observed by TEM. GDF-15−/−/ApoE−/− mice, after CED, showed reduced lumen stenosis in the BT, while body weight, BMI and triglycerides were increased compared with ApoE−/− mice. GDF-15−/− decreased p62-accumulation in atherosclerotic lesions, especially in endothelial cells (ECs). (4) Conclusion: GDF-15 seems to be an important factor in the regulation of autophagy, especially in ECs of atherosclerotic lesions, indicating its crucial pathophysiological function during atherosclerosis development.

IRQC, a surveillance pathway for 40S ribosomal quality control during mRNA translation initiation.

Post-translational modification of ribosomal proteins enables rapid and dynamic regulation of protein biogenesis. Site-specific ubiquitylation of 40S ribosomal proteins uS10 and eS10 plays a key role during ribosome-associated quality control (RQC). Distinct, and previously functionally ambiguous, ubiquitylation events on the 40S proteins uS3 and uS5 are induced by diverse proteostasis stressors that impact translation activity. Here, we identify the ubiquitin ligase RNF10 and the deubiquitylating enzyme USP10 as the key enzymes that regulate uS3 and uS5 ubiquitylation. Prolonged uS3 and uS5 ubiquitylation results in 40S, but not 60S, ribosomal protein degradation in a manner independent of canonical autophagy. We show that blocking progression of either scanning or elongating ribosomes past the start codon triggers site-specific ubiquitylation events on ribosomal proteins uS5 and uS3. This study identifies and characterizes a distinct arm in the RQC pathway, initiation RQC (iRQC), that acts on 40S ribosomes during translation initiation to modulate translation activity and capacity.

Proliferation of Lung Epithelial Cells Is Regulated by the Mechanisms of Autophagy Upon Exposure of Soots

BackgroundSoots are known to cause many diseases in humans, but their underlying mechanisms of toxicity are still not known. Here, we report that soots induce cell proliferation of lung epithelial cells via modulating autophagy pathways.ResultsFullerene soot and diesel exhaust particles (DEP) induced cell proliferation of lung epithelial, A549 cells via distinct autophagic mechanisms and did not cause cell death. Exposure of fullerene soot protected the cell death of A549 cells, caused by hydrogen peroxide, and inhibited LPS-induced autophagy. Fullerene soot co-localized with the autophagic proteins and inhibited starvation-induced autophagy (downregulated ATG-5, beclin-1, p62, and LC3 expressions) independent of its antioxidant properties. Similarly, it decreased the expression profile of autophagic genes and upregulated the proliferation-responsive gene, Ki-67, in mice. We observed that expressions of fullerene soot-responsive genes (Beclin-1, ATG-5, and p62) were reverted by Akt Inhibitor X, indicating an important role of the Akt pathway. At an elemental level, we found that elemental carbon of fullerene soot may be converted into organic carbon, as measured by OCEC, which may point fullerene soot as a source of carbon. On the other hand, DEP upregulated the expressions of autophagy genes. Akt Inhibitor X did not attenuate DEP-induced cell proliferation and autophagic response. However, an autophagic inhibitor, chloroquine, and significantly inhibited DEP-induced cell proliferation.ConclusionIt can be said that distinct autophagic mechanisms are operational in cell proliferation of lung epithelial cells due to soots, which may be responsible for different diseases. Understanding the mechanism of these pathways provides some important targets, which can be utilized for the development of future therapeutics.

The Multifaceted Role of Flavonoids in Cancer Therapy: Leveraging Autophagy with a Double-Edged Sword.

Flavonoids are considered as pleiotropic, safe, and readily obtainable molecules. A large number of recent studies have proposed that flavonoids have potential in the treatment of tumors by the modulation of autophagy. In many cases, flavonoids suppress cancer by stimulating excessive autophagy or impairing autophagy flux especially in apoptosis-resistant cancer cells. However, the anti-cancer activity of flavonoids may be attenuated due to the simultaneous induction of protective autophagy. Notably, flavonoids-triggered protective autophagy is becoming a trend for preventing cancer in the clinical setting or for protecting patients from conventional therapeutic side effects in normal tissues. In this review, focusing on the underlying autophagic mechanisms of flavonoids, we hope to provide a new perspective for clinical application of flavonoids in cancer therapy. In addition, we highlight new research ideas for the development of new dosage forms of flavonoids to improve their various pharmacological effects, establishing flavonoids as ideal candidates for cancer prevention and therapy in the clinic.

High intensity interval training induces dysregulation of mitochondrial respiratory complex and mitophagy in the hippocampus of middle-aged mice

Autophagy is involved in aging-related cognitive impairment. Aerobic exercise training can improve cognitive function in the elderly and this effect may be associated with autophagic mechanisms and mitochondrial respiratory function. High intensity interval training (HIIT) has beneficial effects on heart and skeletal muscles by activating autophagy and/or mitophagy, but the effects of HIIT on autophagy/mitophagy in the aging brain are unknown. This study investigated the effects of HIIT on the mitochondrial respiratory complex and autophagy/mitophagy, and its relation to brain function. Thirteen middle-aged male ICR mice underwent HIIT for 7 weeks. The exercise program reduced the spontaneous behavior and exploration activities of the mice. The phosphorylation level of cAMP response element binding protein (CREB) and the protein expression of brain-derived neurotrophic factor (BDNF) decreased after the 7-week HIIT. Exercise downregulated the protein expression of Complex Ⅰ and upregulated the protein expression of Complex Ⅲ, Complex Ⅳ and Complex Ⅴ. HIIT also decreased the expression of mitophagy-related proteins in the mitochondrial fractions of the hippocampus. However, HIIT did not change the expression of autophagy-related proteins LC3, P62, Atg5, Atg7, Beclin-1 and Lamp2 in the total lysate of the hippocampus. These data indicated that HIIT might have negative effects on the plasticity of the hippocampus in middle-aged mice. The effects may be related to the dysregulation of CREB-BDNF signaling, mitochondrial respiratory complex and mitophagy induced by HIIT.

Colossolactone-G synergizes the anticancer properties of 5-fluorouracil and gemcitabine against colorectal cancer cells

Several terpenoids were isolated from Ganoderma colossum with potential chemotherapeutic properties against different solid tumor cells. Herein, we further assessed the potential chemomodulatory effects of colossolactone-G to gemcitabine (GCB) and 5-fluorouracil (5-FU) against colorectal cancer cells. Colossolactone-G induced moderate cell killing effects against both HT-29 and HCT-116 cells, with IC50’s of 90.5 ± 1.7 µM and 22.3 ± 3.9 µM, respectively. Equitoxic combination demonstrated a synergistic effect between colossolactone-G and GCB, or 5-FU with combination indices ranging from 0.22 to 0.67. Both GCB and 5-FU induced moderate cell cycle arrest at G0/G1-phase and S-phase. Despite colossolactone-G’s lack of influence on cell cycle distribution, it significantly potentiated GCB- and 5-FU-induced cell cycle arrest. Similarly, colossolactone-G treatment alone did not induce pronounced apoptosis in both cell lines. However, 5-FU and GCB induced significant apoptosis which was further potentiated via combination with colossolactone-G. Furthermore, colossolactone-G significantly increased autophagic cell death response in both HCT-116 and HT-29 cells and potentiated 5-FU- and GCB-induced autophagic cell death. The influence of colossolactone-G alone or in combination with GCB or 5-FU on the apoptosis and autophagy were confirmed by qPCR analysis for the expression of several key apoptosis and autophagy genes such as, TRAIL, TP53INP1, BNIP3, hp62, ATG5, ATG7, Lamp2A and the golden standard for autophagy (LC3-II). In conclusion, a synergistic effect in terms of anticancer properties was observed when colossolactone-G was combined with 5-FU and GCB, where it influenced both apoptosis and autophagic cell death mechanisms.

Modulating FKBP5/FKBP51 and autophagy lowers HTT (huntingtin) levels

ABSTRACT Current disease-modifying therapies for Huntington disease (HD) focus on lowering mutant HTT (huntingtin; mHTT) levels, and the immunosuppressant drug rapamycin is an intriguing therapeutic for aging and neurological disorders. Rapamycin interacts with FKBP1A/FKBP12 and FKBP5/FKBP51, inhibiting the MTORC1 complex and increasing cellular clearance mechanisms. Whether the levels of FKBP (FK506 binding protein) family members are altered in HD models and if these proteins are potential therapeutic targets for HD have not been investigated. Here, we found levels of FKBP5 are significantly reduced in HD R6/2 and zQ175 mouse models and human HD isogenic neural stem cells and medium spiny neurons derived from induced pluripotent stem cells. Moreover, FKBP5 interacts and colocalizes with HTT in the striatum and cortex of zQ175 mice and controls. Importantly, when we decreased FKBP5 levels or activity by genetic or pharmacological approaches, we observed reduced levels of mHTT in our isogenic human HD stem cell model. Decreasing FKBP5 levels by siRNA or pharmacological inhibition increased LC3-II levels and macroautophagic/autophagic flux, suggesting autophagic cellular clearance mechanisms are responsible for mHTT lowering. Unlike rapamycin, the effect of pharmacological inhibition with SAFit2, an inhibitor of FKBP5, is MTOR independent. Further, in vivo treatment for 2 weeks with SAFit2, results in reduced HTT levels in both HD R6/2 and zQ175 mouse models. Our studies establish FKBP5 as a protein involved in the pathogenesis of HD and identify FKBP5 as a potential therapeutic target for HD. Abbreviations: ACTB/β-actin: actin beta; AD: Alzheimer disease; BafA1: bafilomycin A1; BCA: bicinchoninic acid; BBB: blood brain barrier; BSA: bovine serum albumin; CoIP: co-immunoprecipitation; DMSO: dimethyl sulfoxide; DTT: dithiothreitol; FKBPs: FK506 binding proteins; HD: Huntington disease; HTT: huntingtin; iPSC: induced pluripotent stem cells; MAP1LC3/LC3:microtubule associated protein 1 light chain 3; MAPT/tau: microtubule associated protein tau; MES: 2-ethanesulfonic acid; MOPS: 3-(N-morphorlino)propanesulfonic acid); MSN: medium spiny neurons; mHTT: mutant huntingtin; MTOR: mechanistic target of rapamycin kinase; NSC: neural stem cells; ON: overnight; PD: Parkinson disease; PPIase: peptidyl-prolyl cis/trans-isomerases; polyQ: polyglutamine; PPP1R1B/DARPP-32: protein phosphatase 1 regulatory inhibitor subunit 1B; PTSD: post-traumatic stress disorder; RT: room temperature; SQSTM1/p62: sequestosome 1; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; TBST:Tris-buffered saline, 0.1% Tween 20; TUBA: tubulin; ULK1: unc-51 like autophagy activating kinase 1; VCL: vinculin; WT: littermate controls.

Evidences for the mechanism of Shenmai injection antagonizing doxorubicin-induced cardiotoxicity

BackgroundDoxorubicin (DOX) is a widely used antitumor drug. However, its clinical application is limited for its serious cardiotoxicity. The mechanism of DOX-induced cardiotoxicity is attributed to the increasing of cell stress in cardiomyocytes, then following autophagic and apoptotic responses. Our previous studies have demonstrated the protective effect of Shenmai injection (SMI) on DOX-induced cardiotoxicity via regulation of inflammatory mediators for releasing cell stress. PurposeTo further investigate whether SMI attenuates the DOX-induced cell stress in cardiomyocytes, we explored the mechanism underlying cell stress as related to Jun N-terminal kinase (JNK) activity and the regulation of autophagic flux to determine the mechanism by which SMI antagonizes DOX-induced cardiotoxicity. Study designThe DOX-induced cardiotoxicity model of autophagic cell death was established in vitro to disclose the protected effects of SMI on oxidative stress, autophagic flux and JNK signaling pathway. Then the autophagic mechanism of SMI antagonizing DOX cardiotoxicity was validated in vivo. ResultsSMI was able to reduce the DOX-induced cardiomyocyte apoptosis associated with inhibition of activation of the JNK pathway and the accumulation of reactive oxygen species (ROS). Besides, SMI antagonized DOX cardiotoxicity, regulated cardiomyocytes homeostasis by restoring DOX-induced cardiomyocytes autophagy. Under specific circumstances, SMI depressed autophagic process by reducing the Beclin 1-Bcl-2 complex dissociation which was activated by DOX via stimulating the JNK signaling pathway. At the same time, SMI regulated lysosomal pH to restore the autophagic flux which was blocked by DOX in cardiomyocytes. ConclusionSMI regulates cardiomyocytes apoptosis and autophagy by controlling JNK signaling pathway, blocking DOX-induced apoptotic pathway and autophagy formation. SMI was also found to play a key role in restoring autophagic flux for counteracting DOX-damaged cardiomyocyte homeostasis.

Pumpkin Seed Extracts Inhibit Proliferation and Induce Autophagy in PC-3 Androgen Insensitive Prostate Cancer Cells.

Pumpkin seed is a rich source of polyphenols and other bioactive compounds that may act as chemopreventive agents against cancer. In this study, five different extracts of pumpkin seeds were evaluated for their ability to affect proliferation and autophagy on PC-3 prostate cancer cells. All extracts (water [W], methanolic, acetone, ethylacetate, and polar lipid [PL]) inhibited cell proliferation in a dose-dependent manner. Treatment of cells with the PL extract increased cell distribution in the S phase, whereas PL and W extracts induced autophagy significantly. Moreover, PL extract induced a remarkable increase of glutathione and oxidized glutathione levels, whereas nitrite and hydrogen peroxide levels were not altered. In conclusion, pumpkin seed extracts affect PC-3 cell viability, oxidative parameters, and autophagic mechanism, thus demonstrating their potential pharmacological use.

Aptamer-Driven Toxin Gene Delivery in U87 Model Glioblastoma Cells.

A novel suicide gene therapy approach was tested in U87 MG glioblastoma multiforme cells. A 26nt G-rich double-stranded DNA aptamer (AS1411) was integrated into a vector at the 5′ of a mammalian codon-optimized saporin gene, under CMV promoter. With this plasmid termed “APTSAP”, the gene encoding ribosome-inactivating protein saporin is driven intracellularly by the glioma-specific aptamer that binds to cell surface-exposed nucleolin and efficiently kills target cells, more effectively as a polyethyleneimine (PEI)-polyplex. Cells that do not expose nucleolin at the cell surface such as 3T3 cells, used as a control, remain unaffected. Suicide gene-induced cell killing was not observed when the inactive saporin mutant SAPKQ DNA was used in the (PEI)-polyplex, indicating that saporin catalytic activity mediates the cytotoxic effect. Rather than apoptosis, cell death has features resembling autophagic or methuosis-like mechanisms. These main findings support the proof-of-concept of using PEI-polyplexed APTSAP for local delivery in rat glioblastoma models.

Interplay of autophagy and cancer stem cells in hepatocellular carcinoma.

Liver cancer is the sixth most common cancer and the fourth leading cause of cancer deaths in the world. The most common type of liver cancers is hepatocellular carcinoma (HCC). Autophagy is the cellular digestion of harmful components by sequestering the waste products into autophagosomes followed by lysosomal degradation for the maintenance of cellular homeostasis. The impairment of autophagy is highly associated with the development and progression of HCC although autophagy may be involved in tumour-suppressing cellular events. In regards to its protecting role, autophagy also shelters the cells from anoikis- a programmed cell death in anchorage-dependent cells detached from the surrounding extracellular matrix which facilitates metastasis in HCC. Liver cancer stem cells (LCSCs) have the ability for self-renewal and differentiation and are associated with the development and progression of HCC by regulating stemness, resistance and angiogenesis. Interestingly, autophagy is also known to regulate normal stem cells by promoting cellular survival and differentiation and maintaining cellular homeostasis. In this review, we discuss the basal autophagic mechanisms and double-faceted roles of autophagy as both tumour suppressor and tumour promoter in HCC, as well as its association with and contribution to self-renewal and differentiation of LCSCs.

Quality Matters? The Involvement of Mitochondrial Quality Control in Cardiovascular Disease

Cardiovascular diseases are one of the leading causes of death and global health problems worldwide. Multiple factors are known to affect the cardiovascular system from lifestyles, genes, underlying comorbidities, and age. Requiring high workload, metabolism of the heart is largely dependent on continuous power supply via mitochondria through effective oxidative respiration. Mitochondria not only serve as cellular power plants, but are also involved in many critical cellular processes, including the generation of intracellular reactive oxygen species (ROS) and regulating cellular survival. To cope with environmental stress, mitochondrial function has been suggested to be essential during bioenergetics adaptation resulting in cardiac pathological remodeling. Thus, mitochondrial dysfunction has been advocated in various aspects of cardiovascular pathology including the response to ischemia/reperfusion (I/R) injury, hypertension (HTN), and cardiovascular complications related to type 2 diabetes mellitus (DM). Therefore, mitochondrial homeostasis through mitochondrial dynamics and quality control is pivotal in the maintenance of cardiac health. Impairment of the segregation of damaged components and degradation of unhealthy mitochondria through autophagic mechanisms may play a crucial role in the pathogenesis of various cardiac disorders. This article provides in-depth understanding of the current literature regarding mitochondrial remodeling and dynamics in cardiovascular diseases.

NUPR1- CHOP experssion, autophagosome formation and apoptosis in the postmortem striatum of chronic methamphetamine user

Methamphetamine (Meth) is a neuro-stimulator substrate which might lead to neural cell death and the activation of several interconnected cellular pathways as well. However, the precise molecular mechanisms underlying Meth-induced neural cell death remained unclear yet. The current study aimed to assess the specific relationship between long-term Meth exposure and several endoplasmic reticulum stress, autophagy, and apoptosis associated markers including C/EBP homologous protein (CHOP), Tribbles homolog 3(Trib3), Nuclear protein 1(NUPR1), and Beclin-1 expression in postmortem human striatum. Therefore, the effects of long-term Meth exposure on autophagy and apoptosis in the striatum of postmortem users were evaluated and molecular, immunehistochemical, and histological examinations were performed on 10 control and 10 Meth-addicted brains. The level of CHOP, Trib3, NUPR1, and Beclin-1, Microtubule-associated proteins 1A/1B light chain 3B(LC3), Caspase 3, and Autophagy protein 5 (ATG5) were measured by using qPCR and immunohistochemistry. Stereological neural cell counting, Hematoxylin and Eosin, Nissl and Tunel staining were also performed. Based on our findings, the expression level of CHOP, Trib3, NUPR1, and Beclin-1 in the striatum of Meth group were significantly higher than the control group. Besides, the neuronal cell death was substantially increased in the striatum based on data obtained from the Tunel assay and the stereological analysis. Long-term presence of Meth in the brain can induce ER stress and overexpression of NUPR1 which is associated with the upregulation of CHOP, a pro-apoptotic transcription factor. Moreover, an increase in Trib3 expression is implicated in CHOP-dependent autophagic cell death during Meth-induced ER stress accompanied by an increase in neuronal cell death in the striatum of the postmortem human brains. Beclin 1 expression was also upregulated which may due to the activation of autophagic mechanisms upon prolonged Meth exposure.

Relevance of Autophagy and Mitophagy Dynamics and Markers in Neurodegenerative Diseases.

During the past few decades, considerable efforts have been made to discover and validate new molecular mechanisms and biomarkers of neurodegenerative diseases. Recent discoveries have demonstrated how autophagy and its specialized form mitophagy are extensively associated with the development, maintenance, and progression of several neurodegenerative diseases. These mechanisms play a pivotal role in the homeostasis of neural cells and are responsible for the clearance of intracellular aggregates and misfolded proteins and the turnover of organelles, in particular, mitochondria. In this review, we summarize recent advances describing the importance of autophagy and mitophagy in neurodegenerative diseases, with particular attention given to multiple sclerosis, Parkinson’s disease, and Alzheimer’s disease. We also review how elements involved in autophagy and mitophagy may represent potential biomarkers for these common neurodegenerative diseases. Finally, we examine the possibility that the modulation of autophagic and mitophagic mechanisms may be an innovative strategy for overcoming neurodegenerative conditions. A deeper knowledge of autophagic and mitophagic mechanisms could facilitate diagnosis and prognostication as well as accelerate the development of therapeutic strategies for neurodegenerative diseases.

XCT 790 is a pharmacological aggrephagy inducer in a yeast model of proteotoxicity.

Aggrephagy is a selective autophagic degradation intracellular mechanism that clears toxic misfolded protein aggregates such as α-synuclein. Here, we identify and demonstrate that the small molecule, XCT 790 alleviates α-synuclein-mediated adverse effects in a yeast model of proteotoxicity. XCT 790 induced general autophagy and also enhanced starvation-induced autophagy. Mechanistically, we showed that XCT 790 clears toxic α-synuclein aggregates in an autophagy-dependent manner. Interestingly, XCT 790 did not demonstrate a synergistic effect on autophagy induction in the presence of another autophagy inducer such as 6-Bio.

Endocytosed silver nanoparticles degrade in lysosomes to form secondary nanoparticle structures during expression of autophagy genes in osteogenic cells

Silver nanoparticles (AgNPs) are increasingly used in combination with biomaterials, such as bone grafts, to provide antimicrobial properties. Our research focused on the cytotoxic and intracellular uptake mechanism of AgNPs on osteogenic cells, and the affected gene expression of osteoblasts exposed to AgNPs. Osteoblast cells were found to be relatively resistant to AgNP exposure, compared to osteoclasts, with a higher IC50 and fewer adverse morphological features. AgNPs were endocytosed within lysosomes, which resulted in the secondary internal formation of curved AgO nano-chains assemblies within the cytosol. Furthermore, osteoblasts demonstrated an oxidative stress response, with autophagic cell death mechanisms, as indicated from qRT2-PCR analysis, with sustained upregulation of the protective gene Heme Oxygenase 1 reaching 86-fold by 48 hours (10 μg/mL). The internalization and fate of AgNPs in osteogenic cells, and the resulting impact on gene expression over time provide further understanding of the nanotoxicity mechanism of AgNPs.