Guidelines for the use and interpretation of assays for monitoring autophagy

Towards Healthy Longevity: Comprehensive Insights from Molecular Targets and Biomarkers to Biological Clocks

Aging is a complex and time-dependent decline in physiological function that affects most organisms, leading to increased risk of age-related diseases. Investigating the molecular underpinnings of aging is crucial to identify geroprotectors, precisely quantify biological age, and propose healthy longevity approaches. This review explores pathways that are currently being investigated as intervention targets and aging biomarkers spanning molecular, cellular, and systemic dimensions. Interventions that target these hallmarks may ameliorate the aging process, with some progressing to clinical trials. Biomarkers of these hallmarks are used to estimate biological aging and risk of aging-associated disease. Utilizing aging biomarkers, biological aging clocks can be constructed that predict a state of abnormal aging, age-related diseases, and increased mortality. Biological age estimation can therefore provide the basis for a fine-grained risk stratification by predicting all-cause mortality well ahead of the onset of specific diseases, thus offering a window for intervention. Yet, despite technological advancements, challenges persist due to individual variability and the dynamic nature of these biomarkers. Addressing this requires longitudinal studies for robust biomarker identification. Overall, utilizing the hallmarks of aging to discover new drug targets and develop new biomarkers opens new frontiers in medicine. Prospects involve multi-omics integration, machine learning, and personalized approaches for targeted interventions, promising a healthier aging population.

Repositioning of antiarrhythmics for prostate cancer treatment: a novel strategy to reprogram cancer-associated fibroblasts towards a tumor-suppressive phenotype

BACKGROUND

Cancer-associated fibroblasts (CAFs) play a significant role in fueling prostate cancer (PCa) progression by interacting with tumor cells. A previous gene expression analysis revealed that CAFs up-regulate genes coding for voltage-gated cation channels, as compared to normal prostate fibroblasts (NPFs). In this study, we explored the impact of antiarrhythmic drugs, known cation channel inhibitors, on the activated state of CAFs and their interaction with PCa cells.

METHODS

The effect of antiarrhythmic treatment on CAF activated phenotype was assessed in terms of cell morphology and fibroblast activation markers. CAF contractility and migration were evaluated by 3D gel collagen contraction and scratch assays, respectively. The ability of antiarrhythmics to impair CAF-PCa cell interplay was investigated in CAF-PCa cell co-cultures by assessing tumor cell growth and expression of epithelial-to-mesenchymal transition (EMT) markers. The effect on in vivo tumor growth was assessed by subcutaneously injecting PCa cells in SCID mice and intratumorally administering the medium of antiarrhythmic-treated CAFs or in co-injection experiments, where antiarrhythmic-treated CAFs were co-injected with PCa cells.

RESULTS

Activated fibroblasts show increased membrane conductance for potassium, sodium and calcium, consistently with the mRNA and protein content analysis. Antiarrhythmics modulate the expression of fibroblast activation markers. Although to a variable extent, these drugs also reduce CAF motility and hinder their ability to remodel the extracellular matrix, for example by reducing MMP-2 release. Furthermore, conditioned medium and co-culture experiments showed that antiarrhythmics can, at least in part, reverse the protumor effects exerted by CAFs on PCa cell growth and plasticity, both in androgen-sensitive and castration-resistant cell lines. Consistently, the transcriptome of antiarrhythmic-treated CAFs resembles that of tumor-suppressive NPFs. In vivo experiments confirmed that the conditioned medium or the direct coinjection of antiarrhythmic-treated CAFs reduced the tumor growth rate of PCa xenografts.

CONCLUSIONS

Collectively, such data suggest a new therapeutic strategy for PCa based on the repositioning of antiarrhythmic drugs with the aim of normalizing CAF phenotype and creating a less permissive tumor microenvironment.

Alpha-Hederin induces incomplete autophagic injury in non-small cell lung cancer by interfering with the lysosomal acidification

Lung cancer is the most common oncological disease worldwide, with non-small cell lung cancer accounting for approximately 85% of lung cancer cases. α-Hederin is a monodesmosidic triterpenoid saponin isolated from the leaves of Hedera helix L. or Nigella sativa and has been extensively studied for its antitumor activity against a variety of tumor cells. It has been suggested that α-Hederin is a potential regulator of autophagy and has high promise for application. However, the specific mechanism and characteristics of α-Hederin in regulating autophagy are not well understood. In this study, we confirmed the potential of α-Hederin application in lung cancer treatment and comprehensively explored the mechanism and characteristics of α-Hederin in regulating autophagy in lung cancer cells. Our results suggest that α-Hederin is an incomplete autophagy inducer that targets mTOR to activate the classical autophagic pathway, inhibits lysosomal acidification without significantly affecting the processes of autophagosome transport, lysosome biogenesis, autophagosome and lysosome fusion, and finally leads to impaired autophagic flux and triggers autophagic damage in NSCLC.

Melatonin-mediated calcineurin inactivation attenuates amyloid beta-induced apoptosis

Alzheimer's disease (AD) is the most common age-related progressive neurodegenerative disorder. The accumulation of amyloid beta-peptide is a neuropathological marker of AD. While melatonin is recognized to have protective effects on aging and neurodegenerative disorders, the therapeutic effect of melatonin on calcineurin in AD is poorly understood. In this study, we examined the effect and underlying molecular mechanisms of melatonin treatment on amyloid beta-mediated neurotoxicity in neuroblastoma cells. Melatonin treatment decreased calcineurin and autophagy in neuroblastoma cells. Electron microscopy images showed that melatonin inhibited amyloid beta-induced autophagic vacuoles. The increase in the amyloid beta-induced apoptosis rate was observed more in PrPC-expressing ZW cells than in PrPC-silencing Zpl cells. Taken together, the results suggest that by mitigating the effect of calcineurin and autophagy flux activation, melatonin could also rescue amyloid beta-induced neurotoxic effects. These findings may be relevant to therapy for neurodegenerative diseases, including AD.

Genotoxic effect of two environmentally safe doses of cadmium on the hepato-nephrocytic system of Bombus atratus forager workers

Eusocial bees are declining due to anthropogenic actions. Individuals can be exposed to contaminants like Cd, which have been found in pollen. Thus, we evaluated the potential genotoxicity of Cd to the hepato-nephrocitic system of Bombus atratus foraging workers exposed to environmentally safe doses of Cd (0.001 mg/kg and 0.003 mg/kg) during 72 h. To assess the genotoxicity of Cd, we conducted an alkaline comet assay. Doses of 0.001 mg/kg of Cd caused comets of levels 2 and 3, and 0.003 mg/kg of Cd induced comets of level 4, while controls exhibited regular nucleoids. Also, 0.003 mg/kg doses caused higher Damage Index, Damage Frequency, and Total Damage. Our results bring new evidence that 0.003 mg/kg Cd exerted genotoxicity to the HNS cells of B. atratus, probably affecting secondary metabolism and the detoxification capability of bees.

Valosin-Containing Protein (VCP): A Review of Its Diverse Molecular Functions and Clinical Phenotypes

In this review we examine the functionally diverse ATPase associated with various cellular activities (AAA-ATPase), valosin-containing protein (VCP/p97), its molecular functions, the mutational landscape of VCP and the phenotypic manifestation of VCP disease. VCP is crucial to a multitude of cellular functions including protein quality control, endoplasmic reticulum-associated degradation (ERAD), autophagy, mitophagy, lysophagy, stress granule formation and clearance, DNA replication and mitosis, DNA damage response including nucleotide excision repair, ATM- and ATR-mediated damage response, homologous repair and non-homologous end joining. VCP variants cause multisystem proteinopathy, and pathology can arise in several tissue types such as skeletal muscle, bone, brain, motor neurons, sensory neurons and possibly cardiac muscle, with the disease course being challenging to predict.

Antiproliferative activities through accelerating autophagic flux by basidalin and its analogs in human cancer cells

Basidalin, isolated from the basidiomycete Leucoagaricus naucina, has previously demonstrated antibacterial and antitumor properties against murine cancer cells in vivo, but its effects on human cancer cells remain unknown. In this study, we found that basidalin possesses antiproliferative activity against human cancer cell lines. To elucidate the antiproliferative mechanism of basidalin, we focused on autophagy. Treatment with basidalin led to an increase in LC3-II expression level, and accelerated autophagic flux through an mTOR-independent pathway. Moreover, according to the structure-activity relationship analysis-including newly synthesized basidalin analogs-the formyl group, not the amino group, contributes to the antiproliferative activities of basidalin against human cancer cells. Additionally, the antiproliferative activity of basidalin analogs was strongly correlated with autophagy-inducing activity, indicating that basidalin exhibits antiproliferative activity through autophagy induction. These data suggest that basidalin, characterized by its ability to upregulate autophagic flux, emerges as a novel anticancer drug.

Failure of Autophagy in Pompe Disease

Autophagy is an evolutionarily conserved lysosome-dependent degradation of cytoplasmic constituents. The system operates as a critical cellular pro-survival mechanism in response to nutrient deprivation and a variety of stress conditions. On top of that, autophagy is involved in maintaining cellular homeostasis through selective elimination of worn-out or damaged proteins and organelles. The autophagic pathway is largely responsible for the delivery of cytosolic glycogen to the lysosome where it is degraded to glucose via acid α-glucosidase. Although the physiological role of lysosomal glycogenolysis is not fully understood, its significance is highlighted by the manifestations of Pompe disease, which is caused by a deficiency of this lysosomal enzyme. Pompe disease is a severe lysosomal glycogen storage disorder that affects skeletal and cardiac muscles most. In this review, we discuss the basics of autophagy and describe its involvement in the pathogenesis of muscle damage in Pompe disease. Finally, we outline how autophagic pathology in the diseased muscles can be used as a tool to fast track the efficacy of therapeutic interventions.

Activation of interleukin 33-NFκB axis in granulosa cells during atresia and its role in disposal of atretic follicles†

It has been previously shown that the cytokine interleukin 33 is required for two processes, i.e., autophagic digestion of granulosa cells and recruitment of macrophages into atretic follicles, for full disposal of atretic follicles. Now, this study shows that activation of interleukin 33-suppression of tumorigenicity 2-Nuclear Factor ĸB (NFκB) axis in granulosa in early atretic follicles may regulate those two events. Injection of human chorionic gonadotropin has been shown to induce a transient peak of interleukin 33 expression with synchronized atresia. In this model, interleukin 33-independent expression of suppression of tumorigenicity 2 in granulosa cells was detected in early atretic follicles before macrophage invasion. The activation of NFκB pathway in ovaries was further demonstrated in vivo in Tg mice with luciferase-reporter for NFκB activation; the activation was microscopically localized to granulosa cells in early atretic follicles. Importantly, antibody blockage of interleukin 33 or interleukin 33 Knock-out (KO) (Il33-/-) not only inhibited NFκB activity in ovaries, but it also altered expression of two key genes, i.e., reduction in proinflammatory interleukin6 (IL6) expression, and a surge of potential autophagy-inhibitory mammalian target of rapamycin (mTOR) expression in atretic follicles. By contrast, apoptosis and other genes, such as interleukin1β (IL1β) were not affected. In conclusion, in parallel to apoptosis, atresia signals also trigger activation of the interleukin 33-suppression of tumorigenicity 2-NFκB pathway in granulosa, which leads to (1) down-regulated expression of mTOR that is a negative regulator of autophagy and (2) up-regulated expression of proinflammatory IL6.

p20BAP31 Induces Autophagy in Colorectal Cancer Cells by Promoting PERK-Mediated ER Stress

B-cell receptor-associated protein 31 (BAP31) is an endoplasmic reticulum (ER) membrane protein involved in apoptosis and autophagy by communication with ER and mitochondria. BAP31 is cleaved by caspase-8 and generates a proapoptotic fragment, p20BAP31, which has shown to induce ER stress and apoptosis through multiple pathways. In this study, we found that p20BAP31 significantly increased the agglomeration of LC3 puncta, suggesting the occurrence of autophagy. Therefore, it is meaningful to explore the mechanism of p20BAP31-induced autophagy, and further analyze the relationships among p20BAP31-induced autophagy, ER stress and apoptosis. The data showed that p20BAP31 induced autophagy by inhibition of the PI3K/AKT/mTOR signaling in colorectal cells. ER stress inhibitor 4-PBA and PERK siRNA alleviated p20BAP31-induced autophagy; in turn, autophagy inhibitors 3-MA and CQ did not affect p20BAP31-induced ER stress, suggesting that p20BAP31-induced ER stress is the upstream of autophagy. We also discovered that ROS inhibitor NAC inhibited p20BAP31-induced autophagy. Furthermore, inhibition of autophagy by CQ suppressed p20BAP31-induced apoptosis and ameliorated cell proliferation. Importantly, p20BAP31 markedly reduced the tumor size in vivo, and significantly enhanced the autophagy levels in the tumor tissues. Collectively, p20BAP31 initiates autophagy by inhibiting the PI3K/AKT/mTOR signaling and activating the PERK-mediated ROS accumulation, further promotes p20BAP31-induced apoptosis and ultimately results in cell death. This study comprehensively reveals the potential mechanism of p20BAP31-induced cell death, which may provide new strategies for antitumor therapy.

Elevated cholesterol in ATAD3 mutants is a compensatory mechanism that leads to membrane cholesterol aggregation

Aberrant cholesterol metabolism causes neurological disease and neurodegeneration, and mitochondria have been linked to perturbed cholesterol homeostasis via the study of pathological mutations in the ATAD3 gene cluster. However, whether the cholesterol changes were compensatory or contributory to the disorder was unclear, and the effects on cell membranes and the wider cell were also unknown. Using patient-derived cells, we show that cholesterol perturbation is a conserved feature of pathological ATAD3 variants that is accompanied by an expanded lysosome population containing membrane whorls characteristic of lysosomal storage diseases. Lysosomes are also more numerous in Drosophila neural progenitor cells expressing mutant Atad3, which exhibit abundant membrane-bound cholesterol aggregates, many of which co-localize with lysosomes. By subjecting the Drosophila Atad3 mutant to nutrient restriction and cholesterol supplementation, we show that the mutant displays heightened cholesterol dependence. Collectively, these findings suggest that elevated cholesterol enhances tolerance to pathological ATAD3 variants; however, this comes at the cost of inducing cholesterol aggregation in membranes, which lysosomal clearance only partly mitigates.

Identification of TFG- and Autophagy-Regulated Proteins and Glycerophospholipids in B Cells

Autophagy supervises the proteostasis and survival of B lymphocytic cells. Trk-fused gene (TFG) promotes autophagosome-lysosome flux in murine CH12 B cells, as well as their survival. Hence, quantitative proteomics of CH12tfgKO and WT B cells in combination with lysosomal inhibition should identify proteins that are prone to lysosomal degradation and contribute to autophagy and B cell survival. Lysosome inhibition via NH4Cl unexpectedly reduced a number of proteins but increased a large cluster of translational, ribosomal, and mitochondrial proteins, independent of TFG. Hence, we propose a role for lysosomes in ribophagy in B cells. TFG-regulated proteins include CD74, BCL10, or the immunoglobulin JCHAIN. Gene ontology (GO) analysis reveals that proteins regulated by TFG alone, or in concert with lysosomes, localize to mitochondria and membrane-bound organelles. Likewise, TFG regulates the abundance of metabolic enzymes, such as ALDOC and the fatty acid-activating enzyme ACOT9. To test consequently for a function of TFG in lipid metabolism, we performed shotgun lipidomics of glycerophospholipids. Total phosphatidylglycerol is more abundant in CH12tfgKO B cells. Several glycerophospholipid species with similar acyl side chains, such as 36:2 phosphatidylethanolamine and 36:2 phosphatidylinositol, show a dysequilibrium. We suggest a role for TFG in lipid homeostasis, mitochondrial functions, translation, and metabolism in B cells.

Autophagy related gene 5 polymorphism rs17587319 (C/G) in asthmatic patients in North Indian population

Objective: Genetic background and environmental stimuli play an important role in asthma, which is an individual's hyper-responsiveness to these stimuli leading to airway inflammation. Autophagy Related Gene 5 (ATG5) plays a critical role in the autophagy pathway and has been shown to be involved in asthma. The genetic polymorphisms in the ATG5 have been reported to predispose individuals to asthma. The role of single nucleotide polymorphism rs17587319 (C/G) of ATG5 in asthma has not been studied so far. Materials and methods: In this study, we in silico analysed rs17587319 (C/G) using web-based tools Human Splice Finder (HSF) and RegulomeDB and further a case-control study was conducted that included 187 blood samples (94 asthmatic and 93 healthy controls). Results: In silico analysis suggested alteration of splicing signals by this intronic variant. The samples were genotyped by applying the PCR-RFLP method. The MAF obtained was 0.022 and 0.043 in healthy controls and asthmatic individuals, respectively. The statistical analysis revealed no association (allelic model, OR = 2.02, 95%CI = 0.59-6.83, p = 0.25; co-dominant model, OR = 2.06, 95%CI = 0.6-7.12, p = 0.24) of rs17587319 (C/G) with the susceptibility to asthma in the north Indian population. Conclusions: In conclusion, rs17587319 (C/G) of ATG5 does not predispose individuals to asthma in our part of the world. Further studies are needed including more number of samples to ascertain the role of this polymorphism in asthma.

An autophagy program that promotes T cell egress from the lymph node controls responses to immune checkpoint blockade

Lymphatic endothelial cells (LECs) of the lymph node (LN) parenchyma orchestrate leukocyte trafficking and peripheral T cell dynamics. T cell responses to immunotherapy largely rely on peripheral T cell recruitment in tumors. Yet, a systematic and molecular understanding of how LECs within the LNs control T cell dynamics under steady-state and tumor-bearing conditions is lacking. Intravital imaging combined with immune phenotyping shows that LEC-specific deletion of the essential autophagy gene Atg5 alters intranodal positioning of lymphocytes and accrues their persistence in the LNs by increasing the availability of the main egress signal sphingosine-1-phosphate. Single-cell RNA sequencing of tumor-draining LNs shows that loss of ATG5 remodels niche-specific LEC phenotypes involved in molecular pathways regulating lymphocyte trafficking and LEC-T cell interactions. Functionally, loss of LEC autophagy prevents recruitment of tumor-infiltrating T and natural killer cells and abrogates response to immunotherapy. Thus, an LEC-autophagy program boosts immune-checkpoint responses by guiding systemic T cell dynamics.

Human cytomegalovirus degrades DMXL1 to inhibit autophagy, lysosomal acidification, and viral assembly

Human cytomegalovirus (HCMV) is an important human pathogen that regulates host immunity and hijacks host compartments, including lysosomes, to assemble virions. We combined a quantitative proteomic analysis of HCMV infection with a database of proteins involved in vacuolar acidification, revealing Dmx-like protein-1 (DMXL1) as the only protein that acidifies vacuoles yet is degraded by HCMV. Systematic comparison of viral deletion mutants reveals the uncharacterized 7 kDa US33A protein as necessary and sufficient for DMXL1 degradation, which occurs via recruitment of the E3 ubiquitin ligase Kip1 ubiquitination-promoting complex (KPC). US33A-mediated DMXL1 degradation inhibits lysosome acidification and autophagic cargo degradation. Formation of the virion assembly compartment, which requires lysosomes, occurs significantly later with US33A-expressing virus infection, with reduced viral replication. These data thus identify a viral strategy for cellular remodeling, with the potential to employ US33A in therapies for viral infection or rheumatic conditions, in which inhibition of lysosome acidification can attenuate disease.

Selective impact of ALK and MELK inhibition on ERα stability and cell proliferation in cell lines representing distinct molecular phenotypes of breast cancer

Breast cancer (BC) is a leading cause of global cancer-related mortality in women, necessitating accurate tumor classification for timely intervention. Molecular and histological factors, including PAM50 classification, estrogen receptor α (ERα), breast cancer type 1 susceptibility protein (BRCA1), progesterone receptor (PR), and HER2 expression, contribute to intricate BC subtyping. In this work, through a combination of bioinformatic and wet lab screenings, followed by classical signal transduction and cell proliferation methods, and employing multiple BC cell lines, we identified enhanced sensitivity of ERα-positive BC cell lines to ALK and MELK inhibitors, inducing ERα degradation and diminishing proliferation in specific BC subtypes. MELK inhibition attenuated ERα transcriptional activity, impeding E2-induced gene expression, and hampering proliferation in MCF-7 cells. Synergies between MELK inhibition with 4OH-tamoxifen (Tam) and ALK inhibition with HER2 inhibitors revealed potential therapeutic avenues for ERα-positive/PR-positive/HER2-negative and ERα-positive/PR-negative/HER2-positive tumors, respectively. Our findings propose MELK as a promising target for ERα-positive/PR-positive/HER2-negative BC and highlight ALK as a potential focus for ERα-positive/PR-negative/HER2-positive BC. The synergistic anti-proliferative effects of MELK with Tam and ALK with HER2 inhibitors underscore kinase inhibitors' potential for selective treatment in diverse BC subtypes, paving the way for personalized and effective therapeutic strategies in BC management.

Intracellular microbial rhodopsin-based optogenetics to control metabolism and cell signaling

Microbial rhodopsin (MRs) ion channels and pumps have become invaluable optogenetic tools for neuroscience as well as biomedical applications. Recently, MR-optogenetics expanded towards subcellular organelles opening principally new opportunities in optogenetic control of intracellular metabolism and signaling via precise manipulations of organelle ion gradients using light. This new optogenetic field expands the opportunities for basic and medical studies of cancer, cardiovascular, and metabolic disorders, providing more detailed and accurate control of cell physiology. This review summarizes recent advances in studies of the cellular metabolic processes and signaling mediated by optogenetic tools targeting mitochondria, endoplasmic reticulum (ER), lysosomes, and synaptic vesicles. Finally, we discuss perspectives of such an optogenetic approach in both fundamental and applied research.

YME1L-mediated mitophagy protects renal tubular cells against cellular senescence under diabetic conditions

BACKGROUND

The senescence of renal tubular epithelial cells (RTECs) is crucial in the progression of diabetic kidney disease (DKD). Accumulating evidence suggests a close association between insufficient mitophagy and RTEC senescence. Yeast mitochondrial escape 1-like 1 (YME1L), an inner mitochondrial membrane metalloprotease, maintains mitochondrial integrity. Its functions in DKD remain unclear. Here, we investigated whether YME1L can prevent the progression of DKD by regulating mitophagy and cellular senescence.

METHODS

We analyzed YME1L expression in renal tubules of DKD patients and mice, explored transcriptomic changes associated with YME1L overexpression in RTECs, and assessed its impact on RTEC senescence and renal dysfunction using an HFD/STZ-induced DKD mouse model. Tubule-specific overexpression of YME1L was achieved through the use of recombinant adeno-associated virus 2/9 (rAAV 2/9). We conducted both in vivo and in vitro experiments to evaluate the effects of YME1L overexpression on mitophagy and mitochondrial function. Furthermore, we performed LC-MS/MS analysis to identify potential protein interactions involving YME1L and elucidate the underlying mechanisms.

RESULTS

Our findings revealed a significant decrease in YME1L expression in the renal tubules of DKD patients and mice. However, tubule-specific overexpression of YME1L significantly alleviated RTEC senescence and renal dysfunction in the HFD/STZ-induced DKD mouse model. Moreover, YME1L overexpression exhibited positive effects on enhancing mitophagy and improving mitochondrial function both in vivo and in vitro. Mechanistically, our LC-MS/MS analysis uncovered a crucial mitophagy receptor, BCL2-like 13 (BCL2L13), as an interacting partner of YME1L. Furthermore, YME1L was found to promote the phosphorylation of BCL2L13, highlighting its role in regulating mitophagy.

CONCLUSIONS

This study provides compelling evidence that YME1L plays a critical role in protecting RTECs from cellular senescence and impeding the progression of DKD. Overexpression of YME1L demonstrated significant therapeutic potential by ameliorating both RTEC senescence and renal dysfunction in the DKD mice. Moreover, our findings indicate that YME1L enhances mitophagy and improves mitochondrial function, potentially through its interaction with BCL2L13 and subsequent phosphorylation. These novel insights into the protective mechanisms of YME1L offer a promising strategy for developing therapies targeting DKD.

Epigenetic Reprogramming of Autophagy Drives Mutant IDH1 Glioma Progression and Response to Radiation

Mutant isocitrate dehydrogenase 1 (mIDH1; IDH1 R132H ) exhibits a gain of function mutation enabling 2-hydroxyglutarate (2HG) production. 2HG inhibits DNA and histone demethylases, inducing epigenetic reprogramming and corresponding changes to the transcriptome. We previously demonstrated 2HG-mediated epigenetic reprogramming enhances DNA-damage response and confers radioresistance in mIDH1 gliomas harboring p53 and ATRX loss of function mutations. In this study, RNA-seq and ChIP-seq data revealed human and mouse mIDH1 glioma neurospheres have downregulated gene ontologies related to mitochondrial metabolism and upregulated autophagy. Further analysis revealed that the decreased mitochondrial metabolism was paralleled by a decrease in glycolysis, rendering autophagy as a source of energy in mIDH1 glioma cells. Analysis of autophagy pathways showed that mIDH1 glioma cells exhibited increased expression of pULK1-S555 and enhanced LC3 I/II conversion, indicating augmented autophagy activity. This dependence is reflected by increased sensitivity of mIDH1 glioma cells to autophagy inhibition. Blocking autophagy selectively impairs the growth of cultured mIDH1 glioma cells but not wild-type IDH1 (wtIDH1) glioma cells. Targeting autophagy by systemic administration of synthetic protein nanoparticles packaged with siRNA targeting Atg7 (SPNP-siRNA-Atg7) sensitized mIDH1 glioma cells to radiation-induced cell death, resulting in tumor regression, long-term survival, and immunological memory, when used in combination with IR. Our results indicate autophagy as a critical pathway for survival and maintenance of mIDH1 glioma cells, a strategy that has significant potential for future clinical translation.

One Sentence Summary

The inhibition of autophagy sensitizes mIDH1 glioma cells to radiation, thus creating a promising therapeutic strategy for mIDH1 glioma patients.

Graphical abstract

Our genetically engineered mIDH1 mouse glioma model harbors IDH1 R132H in the context of ATRX and TP53 knockdown. The production of 2-HG elicited an epigenetic reprogramming associated with a disruption in mitochondrial activity and an enhancement of autophagy in mIDH1 glioma cells. Autophagy is a mechanism involved in cell homeostasis related with cell survival under energetic stress and DNA damage protection. Autophagy has been associated with radio resistance. The inhibition of autophagy thus radio sensitizes mIDH1 glioma cells and enhances survival of mIDH1 glioma-bearing mice, representing a novel therapeutic target for this glioma subtype with potential applicability in combined clinical strategies.

Indoxacarb triggers autophagy and apoptosis through ROS accumulation mediated by oxidative phosphorylation in the midgut of Bombyx mori

Indoxacarb has been widely utilized in agricultural pest management, posing a significant ecological threat to Bombyx mori, a non-target economic insect. In the present study, short-term exposure to low concentration of indoxacarb significantly suppressed the oxidative phosphorylation pathway, and resulted in an accumulation of reactive oxygen species (ROS) in the midgut of B. mori. While, the ATP content exhibited a declining trend but there was no significant change. Moreover, indoxacarb also significantly altered the transcription levels of six autophagy-related genes, and the transcription levels of ATG2, ATG8 and ATG9 were significantly up-regulated by 2.56-, 1.90-, and 3.36-fold, respectively. The protein levels of ATG8-I and ATG8-II and MDC-stained frozen sections further suggested an increase in autophagy. Furthermore, the protein level and enzyme activity of CASP4 showed a significant increase in accordance with the transcription levels of apoptosis-related genes, indicating the activation of the apoptotic signaling pathway. Meanwhile, the induction of apoptosis signals in the midgut cells triggered by indoxacarb was confirmed through TUNEL staining. These findings suggest that indoxacarb can promote the accumulation of ROS by inhibiting the oxidative phosphorylation pathway, thereby inducing autophagy and apoptosis in the midgut cells of B. mori.

The size-dependence and reversibility of polystyrene nanoplastics-induced lipid accumulation in mice: Possible roles of lysosomes

Nanoplastics (NPs) continue to accumulate in global aquatic and terrestrial systems, posing a potential threat to human health through the food chain and/or other pathways. Both in vivo and in vitro studies have confirmed that the liver is one of the main organs targeted for the accumulation of NPs in living organisms. However, whether exposure to NPs induces size-dependent disorders of liver lipid metabolism remains controversial, and the reversibility of NPs-induced hepatotoxicity is largely unknown. In this study, the effects of long-term exposure to environmentally relevant doses of polystyrene nanoplastics (PS-NPs) on lipid accumulation were investigated in terms of autophagy and lysosomal mechanisms. The findings indicated that hepatic lipid accumulation was more pronounced in mice exposed to 100 nm PS-NPs compared to 500 nm PS-NPs. This effect was effectively alleviated after 50 days of self-recovery for 100 nm and 500 nm PS-NPs exposure. Mechanistically, although PS-NPs exposure activated autophagosome formation through ERK (mitogen-activated protein kinase 1)/mTOR (mechanistic target of rapamycin kinase) signaling pathway, the inhibition of Rab7 (RAB7, member RAS oncogene family), CTSB (cathepsin B), and CTSD (cathepsin D) expression impaired lysosomal function, thereby blocking autophagic flux and contributing to hepatic lipid accumulation. After termination of PS-NPs exposure, lysosomal exocytosis was responsible for the clearance of PS-NPs accumulated in lysosomes. Furthermore, impaired lysosomal function and autophagic flux inhibition were effectively alleviated. This might be the main reason for the alleviation of PS-NPs-induced lipid accumulation after recovery. Collectively, we demonstrate for the first time that lysosomes play a dual role in the persistence and reversibility of hepatotoxicity induced by environmental relevant doses of NPs, which provide novel evidence for the prevention and intervention of liver injury associated with nanoplastics exposure.

A comprehensive analysis of the prognostic value and immune microenvironment of lysosome-dependent cell death in glioma: Including glioblastoma and low-grade glioma

Lysosome-dependent cell death (LCD) plays a significant role in overcoming cancer apoptosis and drug resistance. However, the relationship between LCD-associated genes (LCDGs) and glioma, including glioblastoma (GBM) and low-grade glioma (LGG), remains unclear. In this study, an LCDGs risk signature was constructed for glioma patients by utilizing 4 algorithms (Extreme Gradient Boosting, Support Vector Machine, Random Forest, and Generalized Linear Models) to identify core LCDGs. Their correlation with clinical features and the immune microenvironment was also determined in glioma, GBM, and LGG. Additionally, the role of hub LCDGs in various cancers was elucidated via pan-cancer analyses. Validation of the core gene in glioma was performed using qRT-qPCR and immunofluorescence staining analysis. The results showed that the LCDGs risk signature was strongly associated with the prognosis, cancer grades, histological types, and primary therapy outcomes of glioma patients. Furthermore, it was closely linked to the overall survival of LGG patients. Mechanistic analyses revealed a significant association between the risk signature and the immune microenvironment in glioma. Based on differential expression analysis, receiver operating characteristic analysis, and interacted model algorithms, LAPTM4A was identified as a hub LCDG in glioma. It exhibited significant upregulation in glioma, GBM, and LGG samples. Moreover, LAPTM4A expression correlated with the prognosis of glioma and LGG patients, as well as age, grades, histological types, and primary therapy outcomes in glioma. Pan-cancer analysis confirmed that LAPTM4A expression was modulated in the majority of cancers and was associated with the prognosis of various cancers. Mechanistic analyses suggested a strong relationship between LAPTM4A and immune cell infiltration, as well as several drug sensitivities. In conclusion, our findings suggest that LAPTM4A may serve as a potential oncogene associated with LCD in pan-cancer, particularly in glioma, GBM, and LGG. These findings provide important insights for individualized treatment of glioma.

Pyrimethamine upregulates BNIP3 to interfere SNARE-mediated autophagosome-lysosomal fusion in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common tumor types and remains a major clinical challenge. Increasing evidence has revealed that mitophagy inhibitors can enhance the effect of chemotherapy on HCC. However, few mitophagy inhibitors have been approved for clinical use in humans. Pyrimethamine (Pyr) is used to treat infections caused by protozoan parasites. Recent studies have reported that Pyr may be beneficial in the treatment of various tumors. However, its mechanism of action is still not clearly defined. Here, we found that blocking mitophagy sensitized cells to Pyr-induced apoptosis. Mechanistically, Pyr potently induced the accumulation of autophagosomes by inhibiting autophagosome-lysosome fusion in human HCC cells. In vitro and in vivo studies revealed that Pyr blocked autophagosome-lysosome fusion by upregulating BNIP3 to inhibit synaptosomal-associated protein 29 (SNAP29)-vesicle-associated membrane protein 8 (VAMP8) interaction. Moreover, Pyr acted synergistically with sorafenib (Sora) to induce apoptosis and inhibit HCC proliferation in vitro and in vivo. Pyr enhances the sensitivity of HCC cells to Sora, a common chemotherapeutic, by inhibiting mitophagy. Thus, these results provide new insights into the mechanism of action of Pyr and imply that Pyr could potentially be further developed as a novel mitophagy inhibitor. Notably, Pyr and Sora combination therapy could be a promising treatment for malignant HCC.

Muscle Hypertrophy Is Linked to Changes in the Oxidative and Proteolytic Systems during Early Tenderization of the Spanish Breed "Asturiana de los Valles"

For fresh meat consumers, eating satisfaction is of utmost importance and tenderness is one of the most important characteristics in this regard. Our study examined beef of different animal biotypes of the autochthonous breed "Asturiana de los Valles" (AV) to determine if early postmortem oxidative and proteolytic processes may influence the final tenderness of the product. This meat-specialized breed shows different biotypes depending on the frequency of a myostatin mutation "mh" that induces double-muscling or muscular hypertrophy (mh/mh, mh/+, +/+). Samples from the longissimus dorsi muscles of yearling bulls were analyzed during the first 24 h postmortem. Changes in the redox balance of muscle cells were significant in the first hours after slaughter; total antioxidant activity was higher in the mh/mh biotype and it followed the shortening of the sarcomeres, a key parameter in understanding meat tenderness. The two proteolytic systems studied (proteasome and lysosome) followed distinct patterns. Proteasome activity was higher in the (mh/+) biotype, which correlated with higher protein damage. Lysosome proteolysis was increased in the more tender biotypes (mh genotypes). Autophagic activation showed significant differences between the biotypes, with (mh/mh) showing more intense basal autophagy at the beginning of the postmortem period that decreased gradually (p < 0.001), while in the normal biotype (+/+), it was slightly delayed and then increased progressively (p < 0.001). These results suggest that this type of catalytic process and antioxidant activity could contribute to the earlier disintegration of the myofibers, particularly in the mh/mh biotypes, and influence the conversion of muscle into meat.

Exosomal miR-4645-5p from hypoxic bone marrow mesenchymal stem cells facilitates diabetic wound healing by restoring keratinocyte autophagy

BACKGROUND

Refractory diabetic wounds are a common occurrence in patients with diabetes and epidermis-specific macroautophagy/autophagy impairment has been implicated in their pathogenesis. Therefore, identifying and developing treatment strategies capable of normalizing epidermis-specific macroautophagy/autophagy could facilitate diabetic wound healing. The study aims to investigate the potential of bone marrow mesenchymal stem cell-derived exosomes (BMSC-exos) from hypoxic conditions as a treatment to normalize epidermis-specific autophagy for diabetic wound healing.

METHODS

We compared the effects of bone marrow mesenchymal stem cell (BMSC)-sourced exosomes (BMSC-Exos) from hypoxic conditions to those of BMSC in normoxic conditions (noBMSC-Exos). Our studies involved morphometric assessment of the exosomes, identification of the microRNA (miRNA) responsible for the effects, evaluation of keratinocyte functions and examination of effects of the exosomes on several molecules involved in the autophagy pathway such as microtubule-associated protein 1 light chain 3 beta, beclin 1, sequestosome 1, autophagy-related 5 and autophagy-related 5. The experiments used human BMSCs from the American Type Culture Collection, an in vivo mouse model of diabetes (db/db) to assess wound healing, as well as the human keratinocyte HaCaT cell line. In the methodology, the authors utilized an array of approaches that included electron microscopy, small interfering RNA (siRNA) studies, RNA in situ hybridization, quantitative real-time reverse transcription PCR (qRT-PCR), the isolation, sequencing and differential expression of miRNAs, as well as the use of miR-4645-5p-specific knockdown with an inhibitor.

RESULTS

Hypoxia affected the release of exosomes from hypoxic BMSCs (hy-BMSCs) and influenced the size and morphology of the exosomes. Moreover, hyBMSC-Exo treatment markedly improved keratinocyte function, including keratinocyte autophagy, proliferation and migration. miRNA microarray and bioinformatics analysis showed that the target genes of the differentially expressed miRNAs were mainly enriched in 'autophagy' and 'process utilizing autophagic mechanism' in the 'biological process' category and miR-4645-5p as a major contributor to the pro-autophagy effect of hyBMSC-Exos. Moreover, mitogen-activated protein kinase-activated protein kinase 2 (MAPKAPK2) was identified as a potential target of exosomal miR-4645-5p; this was confirmed using a dual luciferase assay. Exosomal miR-4645-5p mediates the inactivation of the MAPKAPK2-induced AKT kinase group (comprising AKT1, AKT2, and AKT3), which in turn suppresses AKT-mTORC1 signaling, thereby facilitating miR-4645-5p-mediated autophagy.

CONCLUSIONS

Overall, the results of this study showed that hyBMSC-Exo-mediated transfer of miR-4645-5p inactivated MAPKAPK2-induced AKT-mTORC1 signaling in keratinocytes, which activated keratinocyte autophagy, proliferation and migration, resulting in diabetic wound healing in mice. Collectively, the findings could aid in the development of a novel therapeutic strategy for diabetic wounds.

Knowledge domain and emerging trends of autophagy in cardiovascular research: A bibliometric analysis

BACKGROUND

Autophagy is essential for the homeostasis and function of the cardiovascular system. Citespace is a visual analysis software developed in the context of scientometrics and data visualization. The purpose of this study is to use Citespace software to conduct bibliometric and visual analysis of the research on autophagy in cardiovascular diseases, identify the current status, hot spots and trends in this field, help researchers clarify the future research focus and direction of autophagy in cardiovascular diseases, and provide more positive and broader ideas for the treatment and drug development of cardiovascular diseases.

METHODS

In the Web of Science Core Collection database to download the data from 2004 to 2022 regarding autophagy in cardiovascular research. CitespaceV was used to collect the research status, hotspots and development trends for visual analysis.

RESULTS

The 3568 articles were published by 547 authors from 397 institutions in 75 countries. From 2004 to 2021, the annual publications increased over time. The top 3 productive nations were China, the United States, and Germany. The leading institution was China's Fudan University. The most cited paper is Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition). The research hotpots include monitoring methods for autophagy activity, changes in autophagy levels in different types of cardiovascular diseases, autophagy signal transduction mechanism in cardiovascular diseases, etc.

CONCLUSION

Bibliometric analysis provided valuable information for autophagy research in cardiovascular disease, which is full of opportunities and challenges. The research of autophagy in the field of cardiovascular diseases is still worthy of in-depth exploration. A challenge with autophagy-targeted therapies is their dichotomy in which the goal is to target maladaptive autophagy while maintaining a baseline level of cell survival to optimize a beneficial outcome. It is necessary for scientists to develop new methods to evaluate the level of autophagy from basic application to human body and reveal the signaling mechanism of autophagy in different types of cardiovascular diseases.

Autophagy in spinal muscular atrophy: from pathogenic mechanisms to therapeutic approaches

Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder caused by the depletion of the ubiquitously expressed survival motor neuron (SMN) protein. While the genetic cause of SMA has been well documented, the exact mechanism(s) by which SMN depletion results in disease progression remain elusive. A wide body of evidence has highlighted the involvement and dysregulation of autophagy in SMA. Autophagy is a highly conserved lysosomal degradation process which is necessary for cellular homeostasis; defects in the autophagic machinery have been linked with a wide range of neurodegenerative disorders, including amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. The pathway is particularly known to prevent neurodegeneration and has been suggested to act as a neuroprotective factor, thus presenting an attractive target for novel therapies for SMA patients. In this review, (a) we provide for the first time a comprehensive summary of the perturbations in the autophagic networks that characterize SMA development, (b) highlight the autophagic regulators which may play a key role in SMA pathogenesis and (c) propose decreased autophagic flux as the causative agent underlying the autophagic dysregulation observed in these patients.

Inhibition of miR-144-3p/FOXO1 Attenuates Diabetic Keratopathy Via Modulating Autophagy and Apoptosis

Purpose

Diabetic keratopathy (DK) is a vision-threatening disease that occurs in people with diabetes. Mounting evidence indicates that microRNAs (miRNAs) are indispensable in nerve regeneration within DK. Herein, the role of miRNAs associated with DK, especially focusing on autophagy and apoptosis regulation, was investigated.

Methods

To identify differentially expressed miRNAs, we performed miRNA sequencing on trigeminal ganglion (TG) tissues derived from streptozotocin-induced type 1 diabetic mellitus (T1DM) and normal mice. MiR-144-3p was chosen for the subsequent experiments. To explore the regulatory role of miR-144-3p in DK, miRNA antagomir was utilized to inhibit miR-144-3p expression. Bioinformatic tools were used to predict the target genes of miR-144-3p, and a dual-luciferase reporter assay was then applied for validation. Autophagy and apoptosis activities were measured utilizing TUNEL staining, immunofluorescence staining, and Western blotting.

Results

Overall, 56 differentially expressed miRNAs were detected in diabetic versus control mice. In the diabetic mouse TG tissue, miR-144-3p expression was aberrantly enhanced, whereas decreasing its expression contributed to improved diabetic corneal re-epithelialization and nerve regeneration. Fork-head Box O1 (FOXO1) was validated as a target gene of miR-144-3p. Overexpression of FOXO1 could prevent both inadequate autophagy and excessive apoptosis in DK. Consistently, a specific miR-144-3p inhibition enhanced autophagy and prevented apoptosis in DK.

Conclusions

In this study, our research confirmed the target binding relationship between miR-144-3p and FOXO1. Inhibiting miR-144-3p might modulate autophagy and apoptosis, which could generate positive outcomes for corneal nerves via targeting FOXO1 in DK.

CLIC1-mediated autophagy confers resistance to DDP in gastric cancer

Gastric cancer has been a constant concern to researchers as one of the most common malignant tumors worldwide. The treatment options for gastric cancer include surgery, chemotherapy and traditional Chinese medicine. Chemotherapy is an effective treatment for patients with advanced gastric cancer. Cisplatin (DDP) has been approved as a critical chemotherapy drug to treat various kinds of solid tumors. Although DDP is an effective chemotherapeutic agent, many patients develop drug resistance during treatment, which has become a severe problem in clinical chemotherapy. This study aims to investigate the mechanism of DDP resistance in gastric cancer. The results show that intracellular chloride channel 1 (CLIC1) expression was increased in AGS/DDP and MKN28/DDP, and as compared to the parental cells, autophagy was activated. In addition, the sensitivity of gastric cancer cells to DDP was decreased compared to the control group, and autophagy increased after overexpression of CLIC1. On the contrary, gastric cancer cells were more sensitive to cisplatin after transfection of CLIC1siRNA or treatment with autophagy inhibitors. These experiments suggest that CLIC1 could alter the sensitivity of gastric cancer cells to DDP by activating autophagy. Overall, the results of this study recommend a novel mechanism of DDP resistance in gastric cancer.

CREBH promotes autophagy to ameliorate NASH by regulating Coro1a

Dysfunctional autophagy aggravates oxidative stress and inflammation in hepatocytes and accelerates the progression of nonalcoholic steatohepatitis (NASH). Here, we demonstrated that cAMP-responsive element-binding protein H (CREBH) is a transcriptional regulator of hepatic autophagy in response to diet-induced NASH. The results showed that the upregulation of CREBH in lipid-overloaded hepatocytes improves cell damage, dysfunction of autophagic flux and associated abnormal accumulation of the autophagosome marker LC3-II and autophagic substrate p62. CREBH deficiency aggravated the dysfunctional autophagy and liver injury and even caused NASH-associated liver fibrosis. In addition, the changing trend of autolysosomes and lysosome membrane-associated protein (LAMP1) was consistent with the expression level of CREBH. This result indicated that CREBH might promote autophagic degradation by restoring the formation of autolysosomes, thereby improving the blocked autophagic flux. Moreover, we observed that CREBH inhibited the expression of Coronin 1a (Coro1a), an autophagosome-lysosome fusion-related gene, through transcriptional regulation. The overexpression of Coro1a in LO2 liver cells inhibited autophagic flux and elevated inflammatory cytokine levels upon palmitic acid (PA) stimulation. Overall, our findings provide new insights into the regulatory role of CREBH in the progression of NASH and reveal that Coro1a is a novel target gene of CREBH based on the autophagy pathway.

Synthetic Activators of Autophagy

Autophagy is a central process for degradation of intracellular components that do not operate correctly. Molecular mechanisms underlying this process are extremely difficult to study, since they involve a large number of participants. The main task of autophagy is redistribution of cellular resources in response to environmental changes, such as starvation. Recent studies show that autophagy regulation could be the key to achieve healthy longevity, as well as to create therapeutic agents for treatment of neurodegenerative diseases such as Parkinson's and Alzheimer's diseases. Thus, development of autophagy activators with established detailed mechanism of action is a really important area of research. Several commercial companies are at various stages of development of such molecules, and some of them have already begun to introduce autophagy activators to the market.

The targeting of DAPK1 with miR-190a-3p promotes autophagy in trophoblast cells

Pre-eclampsia (PE) is a dangerous pathological status that occurs during pregnancy and is a leading reason for both maternal and fetal death. Autophagy is necessary for cellular survival in the face of environmental stress as well as cellular homeostasis and energy management. Aberrant microRNA (miRNA) expression is crucial in the pathophysiology of PE. Although studies have shown that miRNA (miR)-190a-3p function is tissue-specific, the precise involvement of miR-190a-3p in PE has yet to be determined. We discovered that miR-190a-3p was significantly lower and death-associated protein kinase 1 (DAPK1) was significantly higher in PE placental tissues compared to normal tissues, which is consistent with the results in cells. The luciferase analyses demonstrated the target-regulatory relationship between miR-190a-3p and DAPK1. The inhibitory effect of miR-190a-3p on autophagy was reversed by co-transfection of si-DAPK1 and miR-190a-3p inhibitors. Thus, our data indicate that the hypoxia-dependent miR-190a-3p/DAPK1 regulatory pathway is implicated in the development and progression of PE by promoting autophagy in trophoblast cells.

The nonstructural protein 1 of respiratory syncytial virus hijacks host mitophagy as a novel mitophagy receptor to evade the type I IFN response in HEp-2 cells

IMPORTANCE

It is a worthy concern for us to understand virus-host interactions which affect progression and prognosis of disease. We demonstrated that the non-structural protein 1 of respiratory syncytial virus (RSV NS1) may act as a novel mitophagy receptor to induce mitophagy by binding LC3B and mitochondrial protein TUFM, and finally dampen interferon (IFN) responses induced by RIG1 and RSV infection. TUFM is beneficial for RSV replication in vivo and vitro. It is new and interesting that RSV NS1 may function as a mitophagy receptor to interact with LC3B. The LIR motif of NS1 protein is essential for its interaction with LC3B. We further confirm that RSV NS1 inhibited IFNβ response and promoted RSV replication in autophagy-dependent mechanisms in vivo and vitro. Our study contributes to understanding virus-host interaction, enriching our insights into RSV pathogenic mechanism and exploiting new antiviral treatments targeting TUFM.

Mec1-Rad53 Signaling Regulates DNA Damage-Induced Autophagy and Pathogenicity in Candida albicans

DNA damage activates the DNA damage response and autophagy in C. albicans; however, the relationship between the DNA damage response and DNA damage-induced autophagy in C. albicans remains unclear. Mec1-Rad53 signaling is a critical pathway in the DNA damage response, but its role in DNA damage-induced autophagy and pathogenicity in C. albicans remains to be further explored. In this study, we compared the function of autophagy-related (Atg) proteins in DNA damage-induced autophagy and traditional macroautophagy and explored the role of Mec1-Rad53 signaling in regulating DNA damage-induced autophagy and pathogenicity. We found that core Atg proteins are required for these two types of autophagy, while the function of Atg17 is slightly different. Our results showed that Mec1-Rad53 signaling specifically regulates DNA damage-induced autophagy but has no effect on macroautophagy. The recruitment of Atg1 and Atg13 to phagophore assembly sites (PAS) was significantly inhibited in the mec1Δ/Δ and rad53Δ/Δ strains. The formation of autophagic bodies was obviously affected in the mec1Δ/Δ and rad53Δ/Δ strains. We found that DNA damage does not induce mitophagy and ER autophagy. We also identified two regulators of DNA damage-induced autophagy, Psp2 and Dcp2, which regulate DNA damage-induced autophagy by affecting the protein levels of Atg1, Atg13, Mec1, and Rad53. The deletion of Mec1 or Rad53 significantly reduces the ability of C. albicans to systematically infect mice and colonize the kidneys, and it makes C. albicans more susceptible to being killed by macrophages.

Eupatilin inhibits pulmonary fibrosis by activating Sestrin2/PI3K/Akt/mTOR dependent autophagy pathway

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive chronic inflammatory disease with poor clinical outcomes and ineffective drug treatment options. Eupatilin is a major component extracted from the traditional herbal medicine Artemisia asiatica Nakai. Notably, it was demonstrated to have an anti-fibrosis effect in endometrial fibrosis, vocal fold, and hepatic fibrosis. Its role and mechanism in IPF remain unclear.

METHODS

This study used the TGF-β1-induced human embryonic lung fibroblasts (MRC-5) activation, IPF lung fibroblasts, and bleomycin-induced lung fibrosis mice model. Western blot, immunofluorescence staining, quantitative real time-PCR, hematoxylin and eosin staining, Masson's trichrome staining, and immunohistochemistry were used to evaluate the effects of eupatilin on fibroblast activation, pulmonary fibrosis, and autophagy. The autophagosomes were observed with a transmission electron microscope (TEM). RNA sequencing was used to determine the signaling pathway and key regulator related to autophagy.

RESULTS

Eupatilin significantly decreased the expression of Col1A1, fibronectin, α-SMA, and SQSTM1/p62. In contrast, it increased the expression of LC3B II/I and the number of autophagosomes in TGF-β1 treated MRC-5, IPF lung fibroblasts, and bleomycin-induced lung fibrosis mice model; it also alleviated bleomycin-induced lung fibrosis. The KEGG pathway mapping displayed that PI3K/Akt and Sestrin2 were associated with the enhanced fibrogenic process. Eupatilin suppressed the phosphorylation of PI3K/Akt/mTOR. Autophagy inhibitor 3-methyladenine (3-MA) and Akt activator SC-79 abrogated the anti-fibrotic effect of eupatilin. Sestrin2 expression was also downregulated in TGF-β1 treated lung fibroblasts and lung tissues of the bleomycin-induced pulmonary fibrosis mice model. Furthermore, eupatilin promoted Sestrin2 expression, and the knockdown of Sestrin2 significantly aggravated the degree of fibrosis, increased the phosphorylation of PI3K/Akt/mTOR, and decreased autophagy.

CONCLUSION

These findings indicate that eupatilin ameliorates pulmonary fibrosis through Sestrin2/PI3K/Akt/mTOR-dependent autophagy pathway.

ZnO nanoparticles impair autophagic flux and cell viability through the TRIM16-NRF2-p62 pathway in inflammatory keratinocytes

PURPOSE

Zinc oxide nanoparticles (ZnO NPs) are widely used in sunscreen, cosmetics, and topical drugs. Most previous studies have confirmed the safety of ZnO NPs applied to normal skin; however, little is known about the safety and potential toxicity of ZnO NPs applied to inflamed skin. This study aimed to evaluate the exposure risk of ZnO NPs in the treatment of inflammatory skin diseases.

METHODS

Normal human and tumor necrosis factor-α (TNF-α)-induced inflammatory keratinocytes were incubated with ZnO NPs to assess their toxic effects on cell viability and autophagy signaling pathway. Tandem mass tag (TMT)-based proteomics analysis was used to identify differentially expressed proteins following incubation of inflammatory keratinocytes with ZnO NPs. Protein expression was assessed by Western blot, and double fluorescent labeling and siRNA-knockdown further elucidated the role of the TRIM16-NRF2-p62 pathway in mediating the effects of ZnO NP.

RESULTS

In TNF-α-induced inflammatory keratinocytes, ZnO NPs activated cytoprotective autophagy and mediated p62-related autophagic flux block, thereby reducing the viability of inflammatory keratinocytes. Additionally, TRIM16-NRF2 was essential in ZnO NP-mediated autophagy flux block and cell viability reduction in inflammatory keratinocytes. Inhibition of the TRIM16-NRF2 pathway reduced p62 levels, alleviated autophagy flux blockade, and slightly restored the viability of inflammatory keratinocytes.

CONCLUSION

ZnO NPs activated protective cell autophagy. Blockade of autophagy flux mediated by the TRIM16-NRF2-p62 pathway led to decreased cell viability. This study provided a deeper understanding of the toxicity mechanism of ZnO NPs in inflammatory keratinocytes.

Pulmonary tuberculosis biomarker miR-215-5p inhibits autophagosome-lysosome fusion in macrophages

The normal autophagy flux is beneficial for the rapid elimination of phagocytic pathogens by macrophages. However, Mycobacterium tuberculosis interferes with the autophagy flux of macrophages to weaken their immune function and evade immune surveillance. In this study, we found that miRNA-215-5p was downregulated in tuberculosis patients. A potential diagnostic model for tuberculosis was established by combining miRNA-215-5p with three others differentially expressed microRNAs (miRNA-145-5p, miRNA-486-5p and miRNA-628-3p). Furthermore, we discovered that the up-regulated miRNA-215-5p could inhibit the maturation of autophagy by preventing the fusion of autophagosomes with lysosomes in macrophages. The role of TB-specific miRNA-215-5p in inhibiting auto-lysosome formation provides evidence of its potential role in Host-directed therapy for tuberculosis.

Protective effect of ethyl ferulate against hypoxic injury in retinal cells and retinal neovascularization in an oxygen-induced retinopathy model

BACKGROUND

Pathological neovascularization is a major cause of visual impairment in hypoxia-induced retinopathy. Ethyl ferulate (EF), the natural ester derivative of ferulic acid commonly found in Ferula and Angelica Sinensis, has been shown to exert antioxidant, neuroprotective, and anti-inflammatory properties. However, whether EF exerts a protective effect on retinal neovascularization and the underlying mechanisms are not well known.

PURPOSE

The aim of the study was to investigate the effect of EF on retinal neovascularization and explore its underlying molecular mechanisms.

STUDY-DESIGN/METHODS

We constructed hypoxia models induced by cobalt chloride (CoCl2) in ARPE-19 cells and Rhesus choroid-retinal vascular endothelial (RF/6A) cells in vitro, as well as a retinal neovascularization model in oxygen-induced retinopathy (OIR) mice in vivo.

RESULTS

In this work, we demonstrated that EF treatment inhibited hypoxia-induced vascular endothelial growth factor A (VEGFA) expression in ARPE-19 cells and abrogated hypoxia-induced tube formation in RF/6A cells. As expected, intravitreal injection of EF significantly suppressed retinal neovascularization in a dose-dependent manner in OIR retinas. We also found that hypoxia increased VEGFA expression by blocking autophagic flux, whereas EF treatment enhanced autophagic flux, thereby reducing VEGFA expression. Furthermore, EF activated the sequestosome 1 (p62) / nuclear factor E2-related factor 2 (Nrf-2) pathway via upregulating oxidative stress-induced growth inhibitor 1 (OSGIN1) expression, thus alleviating oxidative stress and reducing VEGFA expression.

CONCLUSION

As a result of our findings, EF has an inhibitory effect on retinal neovascularization, implying a potential therapeutic strategy for hypoxia-induced retinopathy.

Impact of ferroptosis on preeclampsia: A review

Preeclampsia (PE) is usually associated with the accumulation of reactive oxygen species (ROS) resulting from heightened oxidative stress (OS). Ferroptosis is a unique type of lipid peroxidation-induced iron-dependent cell death distinct from traditional apoptosis, necroptosis, and pyroptosis and most likely contributes considerable to PE pathogenesis. At approximately 10-12 weeks of gestation, trophoblasts create an environment rich in oxygen and iron. In patients with PE, ferroptosis-related genes such as HIF1 and MAPK8 are downregulated, whereas PLIN2 is upregulated. Furthermore, miR-30b-5p overexpression inhibits solute carrier family 11 member 2, resulting in a decrease in glutathione levels and an increase in the labile iron pool. At the maternal-fetal interface, physiological hypoxia/reperfusion and excessive iron result in lipid peroxidation and ROS production. Owing to the high expression of Fpn and polyunsaturated fatty acid-containing phospholipid-related enzymes, including acyl-CoA synthetase long-chain family member 4, lysophosphatidylcholine acyl-transferase 3, and spermidine/spermine N1-acetyltransferase 1, trophoblasts become more susceptible to OS and ROS damage. In stage 1, the injured trophoblasts exhibit poor invasion and incomplete uterine spiral artery remodeling caused by ferroptosis, leading to placental ischemia and hypoxia. Subsequently, ferroptosis marked by OS occurs in stage 2, eventually causing PE. We aimed to explore the new therapeutic target of PE through OS in ferroptosis.

New insights into the effect of VMP1 on the treatment of pressure overload-induced pathological cardiac hypertrophy: Involving SERCA-regulated autophagic flux

Pathological cardiac hypertrophy is an adaptive reaction in response to pressure or volume overload. Autophagy is critical for damage caused by pathological cardiac hypertrophy. Vacuole membrane protein 1 (VMP1) is an endoplasmic reticulum (ER) transmembrane protein that is effective in activating autophagy. However, the role of VMP1 in pathological cardiac hypertrophy and its underlying mechanisms remain elusive. This study was designed to explore the potential mechanisms of VMP1 on pressure overload-induced pathological cardiac hypertrophy. In this work, abdominal aorta constriction (AAC) surgery was used to induce pathological cardiac hypertrophy in male C57BL/6 mice. H9C2 cardiomyocytes were treated with phenylephrine stimulation (PE) to induce the hypertrophic response. The in vivo results revealed that mice with AAC surgery caused pathological cardiac hypertrophy as evidenced by improved cardiac function according to multiple echocardiographic parameters. Moreover, elevated VMP1 expression was also observed in mice after AAC surgery. VMP1 knockdown aggravated changes in cardiac structure, cardiac dysfunction, and fibrosis. Meanwhile, VMP1 knockdown suppressed autophagy and endoplasmic reticulum calcium ATPase (SERCA) activity in heart tissues. H9C2 cardiomyocytes with VMP1 overexpression were used to investigate the specific mechanism of VMP1 in pathological cardiac hypertrophy, and VMP1 overexpression increased autophagic flux by upregulating SERCA activity. In conclusion, these findings revealed that VMP1 protected against pressure overload-induced pathological cardiac hypertrophy by inducing SERCA-regulated autophagic flux. Our results provide valuable insights regarding the pathophysiology of pathological cardiac hypertrophy and clues to a novel target for the treatment of pathological cardiac hypertrophy.

Enterovirus D68 capsid formation and stability requires acidic compartments

IMPORTANCE

The respiratory picornavirus enterovirus D68 is a causative agent of acute flaccid myelitis, a childhood paralysis disease identified in the last decade. Poliovirus, another picornavirus associated with paralytic disease, is a fecal-oral virus that survives acidic environments when passing from host to host. Here, we follow up on our previous work showing a requirement for acidic intracellular compartments for maturation cleavage of poliovirus particles. Enterovirus D68 requires acidic vesicles for an earlier step, assembly, and maintenance of viral particles themselves. These data have strong implications for the use of acidification blocking treatments to combat enterovirus diseases.

Effects on exocytosis by two HSV-1 mutants unable to block autophagy

IMPORTANCE

Pathogens often hijack extracellular vesicle (EV) biogenesis pathways for assembly, egress, and cell-to-cell spread. Herpes simplex virus 1 (HSV-1) infection stimulated EV biogenesis through a CD63 tetraspanin biogenesis pathway and these EVs activated antiviral responses in recipient cells restricting the infection. HSV-1 inhibits autophagy to evade the host, and increased CD63 exocytosis could be a coping mechanism, as CD63 is involved in both cargo delivery to lysosomes during autophagy and exocytosis. We analyzed exocytosis after infection with two HSV-1 mutants, a ΔICP34.5 and a ΔICP0, that could not inhibit autophagy. Unlike HSV-1(F), neither of these viruses stimulated increased EV biogenesis through the CD63 pathway. ΔICP34.5 stimulated production of microvesicles and apoptotic bodies that were CD63-negative, while ΔICP0 displayed an overall reduced production of EVs. These EVs activated innate immunity gene expression in recipient cells. Given the potential use of these mutants for therapeutic purposes, the immunomodulatory properties of EVs associated with them may be beneficial.

Role of Fyn and the interleukin-6-STAT-3-autophagy axis in sarcopenia

Sarcopenia is the progressive loss of muscle mass wherein Fyn regulates STAT3 to decrease autophagy. To elucidate the role of inflammation in Fyn-STAT3-dependent autophagy and sarcopenia, here we aimed to investigate the underlying mechanisms using two mouse models of primary and secondary sarcopenia: (1) tail suspension and (2) sciatic denervation. In wild-type mice, the expression of Fyn and IL-6 increased significantly. The expression and phosphorylation levels of STAT3 were also significantly augmented, while autophagic activity was abolished. To investigate Fyn-dependency, we used tail suspension with Fyn-null mice. In tail-suspended wild-type mice, IL-6 expression was increased; however, it was abolished in Fyn-null mice, which maintained autophagy and the expression and ablation of STAT3 phosphorylation. In conclusion, Fyn was found to be associated with the IL-6-STAT3-autophagy axis in sarcopenia. This finding permits a better understanding of sarcopenia-associated metabolic diseases and the possible development of therapeutic interventions.

Making the Case for Autophagy Inhibition as a Therapeutic Strategy in Combination with Androgen-Targeted Therapies in Prostate Cancer

Androgen receptor targeting remains the primary therapeutic strategy in prostate cancer, encompassing androgen biosynthesis inhibitors and androgen receptor antagonists. While both androgen-receptor-positive and "castration-resistant" prostate cancer are responsive to these approaches, the development of resistance is an almost inevitable outcome leading to the castration-resistant form of the disease. Given that "cytoprotective" autophagy is considered to be a predominant mechanism of resistance to various chemotherapeutic agents as well as to radiation in the cancer literature, the purpose of this review is to evaluate whether autophagy plays a central role in limiting the utility of androgen deprivation therapies in prostate cancer. Unlike most of our previous reports, where multiple functional forms of autophagy were identified, making it difficult if not impossible to propose autophagy inhibition as a therapeutic strategy, the cytoprotective form of autophagy appears to predominate in the case of androgen deprivation therapies. This opens a potential pathway for improving the outcomes for prostate cancer patients once effective and reliable pharmacological autophagy inhibitors have been developed.

Measurement of SQSTM1 by flow cytometry

Macroautophagy/autophagy is a regulated cellular degradation process essential as a pro-survival mechanism and integral to the regulation of diverse cellular processes in eukaryotes. During cellular stress and nutrient sensing, SQSTM1/p62 (sequestosome 1) functions as a key receptor for selective autophagy by shuttling ubiquitinated cargoes toward autophagic degradation making it a useful marker for monitoring autophagic flux. We present a straightforward and rapid flow cytometric assay for the quantitative measurement of intracellular SQSTM1 with improved sensitivity to conventional immunoblotting and with the benefit of higher throughput and reduced requirements for starting cellular materials for adequate analysis. We demonstrate that flow cytometry is able to detect similar trends in the measurement of intracellular SQSTM1 levels following serum starvation, genetic manipulations, and bafilomycin A1/chloroquine treatments. The assays utilizes readily available reagents and equipment without the need for transfection and utilizes standard flow cytometry equipment. In the present studies, expression of reporter proteins was applied to a range of SQSTM1 expression levels generated by genetic and chemical manipulation in both mouse as well as human cells. In combination with appropriate controls and attention to cautionary issues, this assay offers the ability to assess an important measure of autophagic capacity and flux.Abbreviations: ATG5: autophagy related 5 ATG7: autophagy related 7 BafA: bafilomycin A1 BMDM: bone marrow-derived macrophages CQ: chloroquine EBV: Epstein-Barr Virus EDTA: ethylenediaminetetraacetic acid FBS: fetal bovine serum gMFI: geometric mean fluorescent intensity HD: healthy donor MAP1LC3/LC3/Atg8: microtubule associated protein 1 light chain 3 MedianFI: median fluorescent intensity NTC: non-target control PBMC: peripheral blood mononuclear cells RPMI: Roswell Park Memorial Institution SQSTM1/p62: sequestosome 1 WT: wild type.

Differential regulation of autophagy on urine-concentrating capability through modulating the renal AQP2 expression and renin-angiotensin system in mice

Autophagy, a cellular process of "self-eating," plays an essential role in renal pathophysiology. However, the effect of autophagy on urine-concentrating ability in physiological conditions is still unknown. This study aimed to determine the relevance and mechanisms of autophagy for maintaining urine-concentrating capability during antidiuresis. The extent of the autophagic response to water deprivation (WD) was different between the renal cortex and medulla in mice. Autophagy activity levels in the renal cortex were initially suppressed and then stimulated by WD in a time-dependent manner. During 48 h WD, the urine-concentrating capability of mice was impaired by rapamycin (Rapa) but not by 3-methyladenine (3-MA), accompanied by suppressed renal aquaporin 2 (AQP2), V2 receptor (V2R), renin, and angiotensin-converting enzyme (ACE) expression, and levels of prorenin/renin, angiotensin II (ANG II), and aldosterone in the plasma and urine. In contrast, 3-MA and chloroquine (CQ) suppressed the urine-concentrating capability in WD72 mice, accompanied by downregulation of AQP2 and V2R expression in the renal cortex. 3-MA and CQ further increased AQP2 and V2R expression in the renal medulla of WD72 mice. Compared with 3-MA and CQ, Rapa administration yielded completely opposite results on the above parameters in WD72 mice. In addition, 3-MA and CQ abolished the upregulation of prorenin/renin, ANG II, and aldosterone levels in the plasma and urine in WD72 mice. Taken together, our study demonstrated that autophagy regulated urine-concentrating capability through differential regulation of renal AQP2/V2R and ACE/ANG II signaling during WD.NEW & NOTEWORTHY Autophagy exhibits a double-edged effect on cell survival and plays an essential role in renal pathophysiology. We for the first time reported a novel function of autophagy that controls the urine-concentrating capability in physiological conditions. We found that water deprivation (WD) differentially regulated autophagy in the kidneys of mice in a time-dependent manner and autophagy regulates the urine-concentrating capability mainly by regulating AQP2/V2R and ACE/ANG II signaling in the renal cortex in WD mice.

Molecular mechanism by which RRM2-inhibitor (cholagogue osalmid) plus bafilomycin A1 cause autophagic cell death in multiple myeloma

Despite significant improvement in the prognosis of multiple myeloma (MM), the disease remains incurable; thus, more effective therapies are required. Ribonucleoside-diphosphate reductase subunit M2 (RRM2) is significantly associated with drug resistance, rapid relapse, and poor prognosis. Previously, we found that 4-hydroxysalicylanilide (osalmid), a specific inhibitor of RRM2, exhibits anti-MM activity in vitro, in vivo, and in human patients; however, the mechanism remains unclear. Osalmid inhibits the translocation of RRM2 to the nucleus and stimulates autophagosome synthesis but inhibits subsequent autophagosome-lysosome fusion. We confirm that RRM2 binds to receptor-interacting protein kinase 3 (RIPK3) and reduces RIPK3, inhibiting autophagosome-lysosome fusion. Interestingly, the combination of osalmid and bafilomycin A1 (an autophagy inhibitor) depletes RIPK3 and aggravates p62 and autophagosome accumulation, leading to autophagic cell death. Combination therapy demonstrates synergistic cytotoxicity both in vitro and in vivo. Therefore, we propose that combining osalmid and bafilomycin A1(BafA1) may have clinical benefits against MM.

Meta‑analysis of the autophagy‑associated protein LC3 as a prognostic marker in colorectal cancer

Microtubule-associated protein 1 light chain 3 (LC3) is an autophagy-associated gene, which is involved in the progression of a number of human malignancies. Such as Breast Cancer, Liver Cancer, and Lung Cancer. However, the role of LC3 in colorectal cancer (CC) remains to be fully elucidated. Therefore, the prognostic role of LC3 expression in CC was evaluated in the present study, with an emphasis on the clinicopathology and prognosis. Expression of LC3 in CC was examined using PubMed, Cochrane Library, Excerpta Medica Database, China Knowledge Infrastructure and Wanfang Data. Newcastle-Ottawa scale was used to screen the literature quality, and RevMan 5.4 and STATA 14.0 were used for the meta-analysis. A total of 1,689 patients from 10 studies were included in the present meta-analysis. The findings of the present study suggested that increased LC3 expression levels were associated with histological grade [odds ratio (OR)=0.91, 95% confidence interval (CI) (0.47, 1.77), P<0.001] and TNM stage [OR=0.91, 95% CI (0.47, 1.77), P<0.001], but were not associated with sex [OR=1.14, 95% CI (0.90, 1.51)], age [OR=0.89, 95% CI (0.67, 1.20)], tumor size [OR=0.78, 95% CI (0.30, 2.34)], histological grade [OR=0.82, 95% CI (0.43, 1.95)] and lymph node metastasis [OR=2.05, 95% CI (1.19, 3.60)] in CC. In addition, the increased expression of LC3 was revealed to be a prognostic factor for the overall survival of patients with CC. In conclusion, the autophagy-associated protein LC3 may be a prognostic indicator of human CC.

Enhanced efficacy with reduced toxicity of tripterygium glycoside tablet by compatibility with total glucosides of paeony for rheumatoid arthritis therapy

BACKGROUND AND AIMS

Drug-induced liver injury remains a critical issue to hinder clinical application of Tripterygium Glycosides Tablets (TGTs) for rheumatoid arthritis (RA) therapy. Combination of TGTs with Total Glucosides of Peony (TGP) may be the most common therapeutic strategy for enhancing TGTs' efficacy and reducing its toxicity. Herein, we aimed to investigate the efficacy-enhancing and toxicity-reducing properties and mechanisms of TGT-TGP combination.

METHODS

Both TGT-induced acute and chronic liver injury animal models were established. ELISA, transmission electron microscopy, immunohistochemistry, western blot and quantitative PCR were performed to determine the efficacy, toxicity and regulatory mechanisms of TGT-TGP combination.

RESULTS

The compatibility of TGP significantly reduced the abnormal serum ALT and AST levels, and improved liver histopathological changes in both acute and chronic DILI animal models induced by TGTs, with the most effective dosage of TGP-M (medium-dose TGP, 450 mg/kg). Additionally, TGP and TGT synergistically alleviated joint swelling and improved the elevation of serum inflammatory factors, in line with the positive changes in joint histopathological features of collagen induced arthritis mice, with the same effective dosage of TGP-M following 5 weeks' drug combination treatment. Mechanically, TGT significantly increased the number of autophagosomes and the expression of LC3II protein while reducing p62 protein expression in the liver tissues, which were significantly reversed by the compatibility with TGP, similar to the findings based on the inflamed joint tissues.

CONCLUSIONS

These findings suggest an enhanced efficacy with reduced toxicity of TGT by the compatibility with TGP for RA therapy, possibly through regulating various autophagy-related proteins.

Astrovirus replication is dependent on induction of double-membrane vesicles through a PI3K-dependent, LC3-independent pathway

Human astrovirus is a positive-sense, single-stranded RNA virus. Astrovirus infection causes gastrointestinal symptoms and can lead to encephalitis in immunocompromised patients. Positive-strand RNA viruses typically utilize host intracellular membranes to form replication organelles, which are potential antiviral targets. Many of these replication organelles are double-membrane vesicles (DMVs). Here, we show that astrovirus infection leads to an increase in DMV formation through a replication-dependent mechanism that requires some early components of the autophagy machinery. Results indicate that the upstream class III phosphatidylinositol 3-kinase (PI3K) complex, but not LC3 conjugation machinery, is utilized in DMV formation. Both chemical and genetic inhibition of the PI3K complex lead to significant reduction in DMVs, as well as viral replication. Elucidating the role of autophagy machinery in DMV formation during astrovirus infection reveals a potential target for therapeutic intervention for immunocompromised patients. IMPORTANCE These studies provide critical new evidence that astrovirus replication requires formation of double-membrane vesicles, which utilize class III phosphatidylinositol 3-kinase (PI3K), but not LC3 conjugation autophagy machinery, for biogenesis. These results are consistent with replication mechanisms for other positive-sense RNA viruses suggesting that targeting PI3K could be a promising therapeutic option for not only astrovirus, but other positive-sense RNA virus infections.