p62, Ref(2)P and ubiquitinated proteins are conserved markers of neuronal aging, aggregate formation and progressive autophagic defects

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.

Berberine alleviated contrast-induced acute kidney injury by mitophagy-mediated NLRP3 inflammasome inactivation in a mice model

The incidence of contrast-induced acute kidney injury (CI-AKI) has escalated to become the third most prevalent cause of hospital-acquired AKI, with a lack of efficacious interventions. Berberine (BBR) possesses diverse pharmacological effects and exhibits renoprotective properties; however, limited knowledge exists regarding its impact on CI-AKI. Therefore, our study aimed to investigate the protective effects and underlying mechanisms of BBR on CI-AKI in a mice model, focusing on the nucleotide-binding oligomerization domain-like pyrin domain-containing protein 3 (NLRP3) inflammasome and mitophagy. The CI-AKI mice model was established by administering NG-nitro-L-arginine methyl ester (L-NAME) (10 mg/kg), indomethacin (10 mg/kg), and iohexol (11 g/kg) following water deprivation. A pretreatment of 100 mg/kg of BBR was orally administered to the mice for two weeks. Renal injury markers, damage-associated molecular patterns (DAMPs), renal histopathology, mitochondrial morphology, autophagosomes, and potential mechanisms were investigated. BBR effectively reduced levels of renal injury biomarkers such as serum cystatin C, urea nitrogen, and creatinine, downregulated the protein level of kidney injury molecule 1 (KIM1), and mitigated renal histomorphological damage. Moreover, BBR reduced DAMPs, including high mobility group box-1 (HMGB1), heat shock protein 70 (HSP70), and uric acid (UA). It also alleviated oxidative stress and inflammatory factors such as monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β). Furthermore, the activation of NLRP3 inflammasome was attenuated in the BBR pretreatment group, as evidenced by both mRNA and protein levels. Electron microscopy and western blotting examination revealed that BBR mitigated mitochondrial damage and enhanced mitophagy. Additionally, BBR increased the P-AMPK/AMPK ratio. These findings indicated that BBR exerted a protective effect against CI-AKI by suppressing NLRP3 inflammasome activation and modulating mitophagy, providing a potential therapeutic strategy for its prevention.

Sequestosome 1 (p62) mitigates hypoxia-induced cardiac dysfunction by stabilizing hypoxia-inducible factor 1α and nuclear factor erythroid 2-related factor 2

AIMS

Heart failure due to ischaemic heart disease (IHD) is a leading cause of mortality worldwide. A major contributing factor to IHD-induced cardiac damage is hypoxia. Sequestosome 1 (p62) is a multi-functional adaptor protein with pleiotropic roles in autophagy, proteostasis, inflammation, and cancer. Despite abundant expression in cardiomyocytes, the role of p62 in cardiac physiology is not well understood. We hypothesized that cardiomyocyte-specific p62 deletion evokes hypoxia-induced cardiac pathology by impairing hypoxia-inducible factor 1α (Hif-1α) and nuclear factor erythroid 2-related factor 2 (Nrf2) signalling.

METHODS AND RESULTS

Adult mice with germline deletion of cardiomyocyte p62 exhibited mild cardiac dysfunction under normoxic conditions. Transcriptomic analyses revealed a selective impairment in Nrf2 target genes in the hearts from these mice. Demonstrating the functional importance of this adaptor protein, adult mice with inducible depletion of cardiomyocyte p62 displayed hypoxia-induced contractile dysfunction, oxidative stress, and cell death. Mechanistically, p62-depleted hearts exhibit impaired Hif-1α and Nrf2 transcriptional activity. Because findings from these two murine models suggested a cardioprotective role for p62, mechanisms were evaluated using H9c2 cardiomyoblasts. Loss of p62 in H9c2 cells exposed to hypoxia reduced Hif-1α and Nrf2 protein levels. Further, the lack of p62 decreased Nrf2 protein expression, nuclear translocation, and transcriptional activity. Repressed Nrf2 activity associated with heightened Nrf2-Keap1 co-localization in p62-deficient cells, which was concurrent with increased Nrf2 ubiquitination facilitated by the E3 ligase Cullin 3, followed by proteasomal-mediated degradation. Substantiating our results, a gain of p62 in H9c2 cells stabilized Nrf2 and increased the transcriptional activity of Nrf2 downstream targets.

CONCLUSION

Cardiac p62 mitigates hypoxia-induced cardiac dysfunction by stabilizing Hif-1α and Nrf2.

Lysosomal storage, impaired autophagy and innate immunity in Gaucher and Parkinson's diseases: insights for drug discovery

Impairment of autophagic-lysosomal pathways is increasingly being implicated in Parkinson's disease (PD). GBA1 mutations cause the lysosomal storage disorder Gaucher disease (GD) and are the commonest known genetic risk factor for PD. GBA1 mutations have been shown to cause autophagic-lysosomal impairment. Defective autophagic degradation of unwanted cellular constituents is associated with several pathologies, including loss of normal protein homeostasis, particularly of α-synuclein, and innate immune dysfunction. The latter is observed both peripherally and centrally in PD and GD. Here, we will discuss the mechanistic links between autophagy and immune dysregulation, and the possible role of these pathologies in communication between the gut and brain in these disorders. Recent work in a fly model of neuronopathic GD (nGD) revealed intestinal autophagic defects leading to gastrointestinal dysfunction and immune activation. Rapamycin treatment partially reversed the autophagic block and reduced immune activity, in association with increased survival and improved locomotor performance. Alterations in the gut microbiome are a critical driver of neuroinflammation, and studies have revealed that eradication of the microbiome in nGD fly and mouse models of PD ameliorate brain inflammation. Following these observations, lysosomal-autophagic pathways, innate immune signalling and microbiome dysbiosis are discussed as potential therapeutic targets in PD and GD. This article is part of a discussion meeting issue 'Understanding the endo-lysosomal network in neurodegeneration'.

Maintaining Toll signaling in Drosophila brain is required to sustain autophagy for dopamine neuron survival

Macroautophagy/autophagy is a conserved process in eukaryotic cells to degrade and recycle damaged intracellular components. Higher level of autophagy in the brain has been observed, and autophagy dysfunction has an impact on neuronal health, but the molecular mechanism is unclear. In this study, we showed that overexpression of Toll-1 and Toll-7 receptors, as well as active Spätzle proteins in Drosophila S2 cells enhanced autophagy, and Toll-1/Toll-7 activated autophagy was dependent on Tube-Pelle-PP2A. Interestingly, Toll-1 but not Toll-7 mediated autophagy was dMyd88 dependent. Importantly, we observed that loss of functions in Toll-1 and Toll-7 receptors and PP2A activity in flies decreased autophagy level, resulting in the loss of dopamine (DA) neurons and reduced fly motion. Our results indicated that proper activation of Toll-1 and Toll-7 pathways and PP2A activity in the brain are necessary to sustain autophagy level for DA neuron survival.

OPTN gene therapy increases autophagy and protects mitochondria in SOD1-G93A-expressing transgenic mice and cells

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by progressive motor neuron (MN) death. Mutation of the superoxide dismutase 1 (SOD1) gene, which results in abnormal protein aggregation, is one of the causes of familial ALS. Autophagic dysfunction occurs in SOD1-G93A mutant mice as the disease progresses, but the etiology of this disease is still unclear. Optineurin (OPTN) is an adaptor that is involved in autophagy and participates in aggrephagy and mitophagy. Previous studies have established that OPTN mutations contribute to diseases such as glaucoma and ALS. However, the function of OPTN in autophagy and mitophagy has not been intensively investigated in models of ALS. In this study, we assessed the beneficial effect of OPTN on autophagy and mitochondrial function by intrathecally injecting adeno-associated virus 9 (AAV9)-OPTN into SOD1-G93A transgenic mice and by administering lentivirus (LV)-OPTN to cells expressing the SOD1-G93A mutant protein. The expression of voltage-dependent anion channel 1 (VDAC1) was increased and autophagy was elevated after OPTN gene therapy, as shown by a lower level of p62 and a higher level of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II. Moreover, using electron microscopy, we observed a hyperpolarized mitochondrial transmembrane potential and reversal of mitochondrial morphological abnormalities. Furthermore, the protein level of TANK-binding kinase 1 (TBK1) was increased, suggesting that mitophagy was increased. Our findings from both animal and cell line studies strongly suggest that OPTN gene therapy is a powerful strategy to increase autophagy and protect mitochondria to prevent the progression of ALS and could be effective in the treatment of ALS.

Axonal distribution of mitochondria maintains neuronal autophagy during aging via eIF2β

Neuronal aging and neurodegenerative diseases are accompanied by proteostasis collapse, while cellular factors that trigger it are not identified. Impaired mitochondrial transport in the axon is another feature of aging and neurodegenerative diseases. Using Drosophila, we found that genetic depletion of axonal mitochondria causes dysregulation of translation and protein degradation. Axons with mitochondrial depletion showed abnormal protein accumulation, and autophagic defects. Lowering neuronal ATP levels by blocking glycolysis did not reduce autophagy, suggesting that autophagic defects are associated with mitochondrial distribution. We found eIF2β was upregulated by depletion of axonal mitochondria via proteome analysis. Phosphorylation of eIF2α, another subunit of eIF2, was lowered, and global translation was suppressed. Neuronal overexpression of eIF2β phenocopied the autophagic defects and neuronal dysfunctions, and lowering eIF2β expression rescued those perturbations caused by depletion of axonal mitochondria. These results indicate the mitochondria-eIF2β axis maintains proteostasis in the axon, of which disruption may underly the onset and progression of age-related neurodegenerative diseases.

Integrative analysis reveals a conserved role for the amyloid precursor protein in proteostasis during aging

Aβ peptides derived from the amyloid precursor protein (APP) have been strongly implicated in the pathogenesis of Alzheimer's disease. However, the normal function of APP and the importance of that role in neurodegenerative disease is less clear. We recover the Drosophila ortholog of APP, Appl, in an unbiased forward genetic screen for neurodegeneration mutants. We perform comprehensive single cell transcriptional and proteomic studies of Appl mutant flies to investigate Appl function in the aging brain. We find an unexpected role for Appl in control of multiple cellular pathways, including translation, mitochondrial function, nucleic acid and lipid metabolism, cellular signaling and proteostasis. We mechanistically define a role for Appl in regulating autophagy through TGFβ signaling and document the broader relevance of our findings using mouse genetic, human iPSC and in vivo tauopathy models. Our results demonstrate a conserved role for APP in controlling age-dependent proteostasis with plausible relevance to Alzheimer's disease.

The environmental enrichment ameliorates chronic cerebral hypoperfusion-induced cognitive impairment by activating autophagy signaling pathway and improving synaptic function in hippocampus

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is a frequently observed underlying pathology of both Alzheimer's disease (AD) and vascular dementia (VD), which is a common consequence of cerebral blood flow (CBF) dysregulation. Synaptic damage has been proven as a crucial causative factor for CCH-related cognitive impairment. This study aimed to investigate the neuroprotective impact of environmental enrichment (EE) intervention on CCH-induced synaptic destruction and the consequent cognitive impairment. Furthermore, the underlying mechanism of this neuroprotective effect was explored to provide new insights into therapeutic interventions for individuals suffering from AD or VD.

METHODS

In this experiment, all rats were initially acclimatized to a standard environment (SE) for a period of one week. On the seventh day, rats underwent either bilateral common carotid artery occlusion (2VO) surgery or sham surgery (Sham) before being subjected to a four-week procedure of exposure to an EE, except for the control group. During the EE or SE procedure, intraperitoneal injection of chloroquine (CQ) into rats was performed once daily for four weeks. Following this, cognitive function was assessed using the Morris water maze (MWM) test. The synapse ultrastructure was subsequently observed using transmission electron microscopy. Expression levels of autophagy-related proteins (LC3, LAMP1, and P62) and synapse-related proteins (Synapsin I and PSD-95) were detected through Western blotting. Finally, immunofluorescence was used to examine the expression levels of Synapsin I and PSD-95 and the colocalization of LAMP-1 and LC3 in the hippocampus.

RESULTS

After undergoing 2VO, rats exposed to SE exhibited cognitive impairment, autophagic dysfunction, and synapse damage. The synapse damage was evidenced by ultrastructural damage and degradation of synapse-related proteins. However, these effects were significantly mitigated by exposure to an EE intervention. Moreover, the intervention led to an improvement in autophagic dysfunction.

CONCLUSION

The study found that EE had a positive impact on CCH-induced synaptic damage. Specifically, EE was found to increase synaptic plasticity-associated proteins and postsynaptic density thickness, while decreasing synaptic space. This multifaceted effect resulted in an amelioration of CCH-induced cognitive impairment. It was shown that this beneficial outcome was mediated via the activation of the autophagy-lysosomal pathway. Overall, the findings suggest that EE may have a therapeutic potential for cognitive impairments associated with CCH through autophagy-mediated synaptic improvement.

Impaired autophagy in the lower airways and lung parenchyma in stable COPD

Background

There is increasing evidence of autophagy activation in COPD, but its role is complex and probably regulated through cell type-specific mechanisms. This study aims to investigate the autophagic process at multiple levels within the respiratory system, using different methods to clarify conflicting results reported so far.

Methods

This cross-sectional study was performed on bronchial biopsies and peripheral lung samples obtained from COPD patients (30 and 12 per sample type, respectively) and healthy controls (25 and 22 per sample type, respectively), divided by smoking history. Subjects were matched for age and smoking history. We analysed some of the most important proteins involved in autophagosome formation, such as LC3 and p62, as well as some molecules essential for lysosome function, such as lysosome-associated membrane protein 1 (LAMP1). Immunohistochemistry was used to assess the autophagic process in both sample types. ELISA and transcriptomic analysis were performed on lung samples.

Results

We found increased autophagic stimulus in smoking subjects, regardless of respiratory function. This was revealed by immunohistochemistry through a significant increase in LC3 (p<0.01) and LAMP1 (p<0.01) in small airway bronchiolar epithelium, alveolar septa and alveolar macrophages. Similar results were obtained in bronchial biopsy epithelium by evaluating LC3B (p<0.05), also increased in homogenate lung tissue using ELISA (p<0.05). Patients with COPD, unlike the others, showed an increase in p62 by ELISA (p<0.05). No differences were found in transcriptomics analysis.

Conclusions

Different techniques, applied at post-transcriptional level, confirm that cigarette smoke stimulates autophagy at multiple levels inside the respiratory system, and that autophagy failure may characterise COPD.

Toxicity of C9orf72-associated dipeptide repeat peptides is modified by commonly used protein tags

Hexanucleotide repeat expansions in the C9orf72 gene are the most prevalent genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. Transcripts of the expansions are translated into toxic dipeptide repeat (DPR) proteins. Most preclinical studies in cell and animal models have used protein-tagged polyDPR constructs to investigate DPR toxicity but the effects of tags on DPR toxicity have not been systematically explored. Here, we used Drosophila to assess the influence of protein tags on DPR toxicity. Tagging of 36 but not 100 arginine-rich DPRs with mCherry increased toxicity, whereas adding mCherry or GFP to GA100 completely abolished toxicity. FLAG tagging also reduced GA100 toxicity but less than the longer fluorescent tags. Expression of untagged but not GFP- or mCherry-tagged GA100 caused DNA damage and increased p62 levels. Fluorescent tags also affected GA100 stability and degradation. In summary, protein tags affect DPR toxicity in a tag- and DPR-dependent manner, and GA toxicity might be underestimated in studies using tagged GA proteins. Thus, including untagged DPRs as controls is important when assessing DPR toxicity in preclinical models.

Autophagy blockage and lysosomal dysfunction are involved in diallyl sulfide-induced inhibition of malignant growth in hepatocellular carcinoma cells

Diallyl sulfide (DAS), as a major component of garlic extracts, has been shown to inhibit growth of hepatocellular carcinoma cells (HCC), but the underlying mechanism is still elusive. In this study, we aimed to explore the involvement of autophagy in DAS-induced growth inhibition of HepG2 and Huh7 hepatocellular carcinoma cells. We studied growth of DAS-treated HepG2 and Huh7 cells using the MTS and clonogenic assays. Autophagic flux was examined by immunofluorescence and confocal microscopy. The expression levels of autophagy-related proteins AMPK, mTOR, p62, LC3-II, LAMP1, and cathepsin D in the HepG2 and Huh7 cells treated with DAS as well as the tumors formed by HepG2 cells in the nude mice in the presence or absence of DAS were examined using western blotting and immunohistochemistry analysis. We found that DAS treatment induced activation of AMPK/mTOR, and accumulation of LC3-II and p62 both in vivo and in vitro. DAS inhibited autophagic flux through blocking the fusion of autophagosomes with lysosomes. Furthermore, DAS induced an increase in lysosomal pH and inhibition of Cathepsin D maturation. Co-treatment with an autophagy inhibitor (Chloroquine, CQ) further enhanced the growth inhibitory activity of DAS in HCC cells. Thus, our findings indicate that autophagy is involved in DAS-mediated growth inhibition of HCC cells both in vitro and in vivo.

SQSTM1 is a therapeutic target for infection and sterile inflammation

Inflammation represents a fundamental immune response triggered by various detrimental stimuli, such as infections, tissue damage, toxins, and foreign substances. Protein degradation plays a crucial role in regulating the inflammatory process at multiple levels. The identification of sequestosome 1 (SQSTM1, also known as p62) protein as a binding partner of lymphocyte-specific protein tyrosine kinase in 1995 marked a significant milestone. Subsequent investigations unveiled the activity of SQSTM1 to interact with diverse unstructured substrates, including proteins, organelles, and pathogens, facilitating their delivery to the lysosome for autophagic degradation. In addition to its well-established intracellular functions, emerging studies have reported the active secretion or passive release of SQSTM1 by immune or non-immune cells, orchestrating the inflammatory responses. These distinct characteristics render SQSTM1 a critical therapeutic target in numerous human diseases, including infectious diseases, rheumatoid arthritis, inflammatory bowel disease, pancreatitis, asthma, chronic obstructive pulmonary disease, and cardiovascular diseases. This review provides a comprehensive overview of the structure and modulation of SQSTM1, discusses its intracellular and extracellular roles in inflammation, and highlights its significance in inflammation-related diseases. Future investigations focusing on elucidating the precise localization, structure, post-translational modifications of SQSTM1, as well as the identification of additional interacting partners, hold promise for unravelling further insights into the multifaceted functions of SQSTM1.

Drosophila melanogaster as a model to study autophagy in neurodegenerative diseases induced by proteinopathies

Proteinopathies are a large group of neurodegenerative diseases caused by both genetic and sporadic mutations in particular genes which can lead to alterations of the protein structure and to the formation of aggregates, especially toxic for neurons. Autophagy is a key mechanism for clearing those aggregates and its function has been strongly associated with the ubiquitin-proteasome system (UPS), hence mutations in both pathways have been associated with the onset of neurodegenerative diseases, particularly those induced by protein misfolding and accumulation of aggregates. Many crucial discoveries regarding the molecular and cellular events underlying the role of autophagy in these diseases have come from studies using Drosophila models. Indeed, despite the physiological and morphological differences between the fly and the human brain, most of the biochemical and molecular aspects regulating protein homeostasis, including autophagy, are conserved between the two species.In this review, we will provide an overview of the most common neurodegenerative proteinopathies, which include PolyQ diseases (Huntington's disease, Spinocerebellar ataxia 1, 2, and 3), Amyotrophic Lateral Sclerosis (C9orf72, SOD1, TDP-43, FUS), Alzheimer's disease (APP, Tau) Parkinson's disease (a-syn, parkin and PINK1, LRRK2) and prion diseases, highlighting the studies using Drosophila that have contributed to understanding the conserved mechanisms and elucidating the role of autophagy in these diseases.

The Small-Molecule Enhancers of Autophagy AUTEN-67 and -99 Delay Ageing in Drosophila Striated Muscle Cells

Autophagy (cellular self-degradation) plays a major role in maintaining the functional integrity (homeostasis) of essentially all eukaryotic cells. During the process, superfluous and damaged cellular constituents are delivered into the lysosomal compartment for enzymatic degradation. In humans, age-related defects in autophagy have been linked to the incidence of various age-associated degenerative pathologies (e.g., cancer, neurodegenerative diseases, diabetes, tissue atrophy and fibrosis, and immune deficiency) and accelerated ageing. Muscle mass decreases at detectable levels already in middle-aged patients, and this change can increase up to 30-50% at age 80. AUTEN-67 and -99, two small-molecule enhancers of autophagy with cytoprotective and anti-ageing effects have been previously identified and initially characterized. These compounds can increase the life span in wild-type and neurodegenerative model strains of the fruit fly Drosophila melanogaster. Adult flies were treated with these AUTEN molecules via feeding. Fluorescence and electron microscopy and Western blotting were used to assess the level of autophagy and cellular senescence. Flying tests were used to measure the locomotor ability of the treated animals at different ages. In the current study, the effects of AUTEN-67 and -99 were observed on striated muscle cells using the Drosophila indirect flight muscle (IFM) as a model. The two molecules were capable of inducing autophagy in IFM cells, thereby lowering the accumulation of protein aggregates and damaged mitochondria, both characterizing muscle ageing. Furthermore, the two molecules significantly improved the flying ability of treated animals. AUTEN-67 and -99 decrease the rate at which striated muscle cells age. These results may have a significant medical relevance that could be further examined in mammalian models.

A neuroprotective role of Ufmylation through Atg9 in the aging brain of Drosophila

Ufmylation is a recently identified small ubiquitin-like modification, whose biological function and relevant cellular targets are poorly understood. Here we present evidence of a neuroprotective role for Ufmylation involving Autophagy-related gene 9 (Atg9) during Drosophila aging. The Ufm1 system ensures the health of aged neurons via Atg9 by coordinating autophagy and mTORC1, and maintaining mitochondrial homeostasis and JNK (c-Jun N-terminal kinase) activity. Neuron-specific expression of Atg9 suppresses the age-associated movement defect and lethality caused by loss of Ufmylation. Furthermore, Atg9 is identified as a conserved target of Ufm1 conjugation mediated by Ddrgk1, a critical regulator of Ufmylation. Mammalian Ddrgk1 was shown to be indispensable for the stability of endogenous Atg9A protein in mouse embryonic fibroblast (MEF) cells. Taken together, our findings might have important implications for neurodegenerative diseases in mammals.

Chitinase-like proteins promoting tumorigenesis through disruption of cell polarity via enlarged endosomal vesicles

Introduction

Chitinase-like proteins (CLPs) are associated with tissue-remodeling and inflammation but also with several disorders, including fibrosis, atherosclerosis, allergies, and cancer. However, CLP's role in tumors is far from clear.

Methods

Here, we utilize Drosophila melanogaster and molecular genetics to investigate the function of CLPs (imaginal disc growth factors; Idgf's) in Ras^V12 dysplastic salivary glands.

Results and discussion

We find one of the Idgf's members, Idgf3, is transcriptionally induced in a JNK-dependent manner via a positive feedback loop mediated by reactive oxygen species (ROS). Moreover, Idgf3 accumulates in enlarged endosomal vesicles (EnVs) that promote tumor progression by disrupting cytoskeletal organization. The process is mediated via the downstream component, aSpectrin, which localizes to the EnVs. Our data provide new insight into CLP function in tumors and identifies specific targets for tumor control.

A brain-wide form of presynaptic active zone plasticity orchestrates resilience to brain aging in Drosophila

The brain as a central regulator of stress integration determines what is threatening, stores memories, and regulates physiological adaptations across the aging trajectory. While sleep homeostasis seems to be linked to brain resilience, how age-associated changes intersect to adapt brain resilience to life history remains enigmatic. We here provide evidence that a brain-wide form of presynaptic active zone plasticity ("PreScale"), characterized by increases of active zone scaffold proteins and synaptic vesicle release factors, integrates resilience by coupling sleep, longevity, and memory during early aging of Drosophila. PreScale increased over the brain until mid-age, to then decreased again, and promoted the age-typical adaption of sleep patterns as well as extended longevity, while at the same time it reduced the ability of forming new memories. Genetic induction of PreScale also mimicked early aging-associated adaption of sleep patterns and the neuronal activity/excitability of sleep control neurons. Spermidine supplementation, previously shown to suppress early aging-associated PreScale, also attenuated the age-typical sleep pattern changes. Pharmacological induction of sleep for 2 days in mid-age flies also reset PreScale, restored memory formation, and rejuvenated sleep patterns. Our data suggest that early along the aging trajectory, PreScale acts as an acute, brain-wide form of presynaptic plasticity to steer trade-offs between longevity, sleep, and memory formation in a still plastic phase of early brain aging.

Glial control of sphingolipid levels sculpts diurnal remodeling in a circadian circuit

Structural plasticity in the brain often necessitates dramatic remodeling of neuronal processes, with attendant reorganization of the cytoskeleton and membranes. Although cytoskeletal restructuring has been studied extensively, how lipids might orchestrate structural plasticity remains unclear. We show that specific glial cells in Drosophila produce glucocerebrosidase (GBA) to locally catabolize sphingolipids. Sphingolipid accumulation drives lysosomal dysfunction, causing gba1b mutants to harbor protein aggregates that cycle across circadian time and are regulated by neural activity, the circadian clock, and sleep. Although the vast majority of membrane lipids are stable across the day, a specific subset that is highly enriched in sphingolipids cycles daily in a gba1b-dependent fashion. Remarkably, both sphingolipid biosynthesis and degradation are required for the diurnal remodeling of circadian clock neurites, which grow and shrink across the day. Thus, dynamic sphingolipid regulation by glia enables diurnal circuit remodeling and proper circadian behavior.

Synergistic effects of epigallocatechin gallate and l-theanine in nerve repair and regeneration by anti-amyloid damage, promoting metabolism, and nourishing nerve cells

Green tea has significant protective activity on nerve cells, but the mechanism of action is unclear. Epigallocatechin gallate (EGCG) and N-ethyl-L-glutamine (L-theanine) are the representative functional components of green tea (Camellia sinensis). In this study, an AD model of Aβ_25–35-induced differentiated neural cell line PC12 cells was established to study the synergistic effect of EGCG and L-theanine in protecting neural cells. The results showed that under Aβ_25–35 stress conditions, mitochondria and axons degenerated, and the expression of cyclins was up-regulated, showing the gene and protein characteristics of cellular hyperfunction. EGCG + L-theanine inhibited inflammation and aggregate formation pathways, significantly increased the percentage of G0/G1 in the cell cycle, downregulated the expression of proteins such as p-mTOR, Cyclin D1, and Cyclin B1, upregulated the expression of GAP43, Klotho, p-AMPK, and other proteins, promoted mitochondrial activity and energy metabolism, and had repair and regeneration effects on differentiated nerve cells. The synergistic mechanism study showed that under the premise that EGCG inhibits amyloid stress and inflammation and promotes metabolism, L-theanine could play a nourish nerve effect. EGCG + L-theanine keeps differentiated nerve cells in a quiescent state, which is beneficial to the repair and regeneration of nerve cells. In addition, EGCG + L-theanine maintains the high-fidelity structure of cellular proteins. This study revealed for the first time that the synergistic effect of EGCG with L-theanine may be an effective way to promote nerve cell repair and regeneration and slow down the progression of AD. Our findings provide a new scientific basis for the relationship between tea drinking and brain protection.

Loss of mitochondrial enzyme GPT2 causes early neurodegeneration in locus coeruleus

Locus coeruleus (LC) is among the first brain areas to degenerate in Alzheimer’s disease and Parkinson’s disease; however, the underlying causes for the vulnerability of LC neurons are not well defined. Here we report a novel mechanism of degeneration of LC neurons caused by loss of the mitochondrial enzyme glutamate pyruvate transaminase 2 (GPT2). GPT2 Deficiency is a newly-recognized childhood neurometabolic disorder. The GPT2 enzyme regulates cell growth through replenishment of tricarboxylic acid (TCA) cycle intermediates and modulation of amino acid metabolism. In Gpt2-null mice, we observe an early loss of tyrosine hydroxylase (TH)-positive neurons in LC and reduced soma size at postnatal day 18. Gpt2-null LC shows selective positive Fluoro-Jade C staining. Neuron loss is accompanied by selective, prominent microgliosis and astrogliosis in LC. We observe reduced noradrenergic projections to and norepinephrine levels in hippocampus and spinal cord. Whole cell recordings in Gpt2-null LC slices show reduced soma size and abnormal action potentials with altered firing kinetics. Strikingly, we observe early decreases in phosphorylated S6 in Gpt2-null LC, preceding prominent p62 aggregation, increased LC3B-II to LC3B-I ratio, and neuronal loss. These data are consistent with a possible mechanism involving deficiency in protein synthesis and cell growth, associated subsequently with abnormal autophagy and neurodegeneration. As compared to the few genetic animal models with LC degeneration, loss of LC neurons in Gpt2-null mice is developmentally the earliest. Early neuron loss in LC in a model of human neurometabolic disease provides important clues regarding the metabolic vulnerability of LC and may lead to new therapeutic targets.

Therapeutic Intervention in Cancer by Isoliquiritigenin from Licorice: A Natural Antioxidant and Redox Regulator

Oxidative stress could lead to a variety of body dysfunctions, including neurodegeneration and cancer, which are closely associated with intracellular signal transducers such as reactive oxygen species (ROS). It has been suggested that ROS is the upstream regulator of autophagy, and that it provides a negative feedback regulation to remove oxidative damage. Defects in the ROS-autophagic redox homeostasis could lead to the increased production of ROS and the accumulation of damaged organelles that in turn promote metabolic reprogramming and induce tumorigenesis. One significant characteristic of pancreatic cancer is the reprogramming of cellular energy metabolism, which facilitates the rapid growth, invasiveness, and the survival of cancer cells. Thus, the rectification of metabolic dysfunction is essential in therapeutic cancer targeting. Isoliquiritigenin (ISL) is a chalcone obtained from the plant Glycyrrhiza glabra, which is a powdered root licorice that has been consumed for centuries in different regions of the world. ISL is known to be a natural antioxidant that possesses diversified functions, including redox regulation in cells. This review contains discussions on the herbal source, biological properties, and anticancer potential of ISL. This is the first time that the anticancer activities of ISL in pancreatic cancer has been elucidated, with a coverage of the involvement of antioxidation, metabolic redox regulation, and autophagy in pancreatic cancer development. Furthermore, some remarks on related compounds of the isoflavonoid biosynthetic pathway of ISL will also be discussed.

Dietary restriction ameliorates TBI-induced phenotypes in Drosophila melanogaster

Traumatic brain injury (TBI) affects millions annually and is associated with long-term health decline. TBI also shares molecular and cellular hallmarks with neurodegenerative diseases (NDs), typically increasing in prevalence with age, and is a major risk factor for developing neurodegeneration later in life. While our understanding of genes and pathways that underlie neurotoxicity in specific NDs has advanced, we still lack a complete understanding of early molecular and physiological changes that drive neurodegeneration, particularly as an individual ages following a TBI. Recently Drosophila has been introduced as a model organism for studying closed-head TBI. In this paper, we deliver a TBI to flies early in adult life, and then measure molecular and physiological phenotypes at short-, mid-, and long-term timepoints following the injury. We aim to identify the timing of changes that contribute to neurodegeneration. Here we confirm prior work demonstrating a TBI-induced decline in lifespan, and present evidence of a progressive decline in locomotor function, robust acute and modest chronic neuroinflammation, and a late-onset increase in protein aggregation. We also present evidence of metabolic dysfunction, in the form of starvation sensitivity and decreased lipids, that persists beyond the immediate injury response, but does not differ long-term. An intervention of dietary restriction (DR) partially ameliorates some TBI-induced phenotypes, including lifespan and locomotor function, though it does not alter the pattern of starvation sensitivity of injured flies. In the future, molecular pathways identified as altered following TBI—particularly in the short-, or mid-term—could present potential therapeutic targets.

Biological aging processes underlying cognitive decline and neurodegenerative disease

Alzheimer's disease and related dementias (ADRD) are among the top contributors to disability and mortality in later life. As with many chronic conditions, aging is the single most influential factor in the development of ADRD. Even among older adults who remain free of dementia throughout their lives, cognitive decline and neurodegenerative changes are appreciable with advancing age, suggesting shared pathophysiological mechanisms. In this Review, we provide an overview of changes in cognition, brain morphology, and neuropathological protein accumulation across the lifespan in humans, with complementary and mechanistic evidence from animal models. Next, we highlight selected aging processes that are differentially regulated in neurodegenerative disease, including aberrant autophagy, mitochondrial dysfunction, cellular senescence, epigenetic changes, cerebrovascular dysfunction, inflammation, and lipid dysregulation. We summarize research across clinical and translational studies to link biological aging processes to underlying ADRD pathogenesis. Targeting fundamental processes underlying biological aging may represent a yet relatively unexplored avenue to attenuate both age-related cognitive decline and ADRD. Collaboration across the fields of geroscience and neuroscience, coupled with the development of new translational animal models that more closely align with human disease processes, is necessary to advance novel therapeutic discovery in this realm.

S-Nitrosylation of p62 Inhibits Autophagic Flux to Promote α-Synuclein Secretion and Spread in Parkinson's Disease and Lewy Body Dementia

Dysregulation of autophagic pathways leads to accumulation of abnormal proteins and damaged organelles in many neurodegenerative disorders, including Parkinson's disease (PD) and Lewy body dementia (LBD). Autophagy-related dysfunction may also trigger secretion and spread of misfolded proteins, such as α-synuclein (α-syn), the major misfolded protein found in PD/LBD. However, the mechanism underlying these phenomena remains largely unknown. Here, we used cell-based models, including human induced pluripotent stem cell-derived neurons, CRISPR/Cas9 technology, and male transgenic PD/LBD mice, plus vetting in human postmortem brains (both male and female). We provide mechanistic insight into this pathologic pathway. We find that aberrant S-nitrosylation of the autophagic adaptor protein p62 causes inhibition of autophagic flux and intracellular buildup of misfolded proteins, with consequent secretion resulting in cell-to-cell spread. Thus, our data show that pathologic protein S-nitrosylation of p62 represents a critical factor not only for autophagic inhibition and demise of individual neurons, but also for α-syn release and spread of disease throughout the nervous system.SIGNIFICANCE STATEMENT In Parkinson's disease and Lewy body dementia, dysfunctional autophagy contributes to accumulation and spread of aggregated α-synuclein. Here, we provide evidence that protein S-nitrosylation of p62 inhibits autophagic flux, contributing to α-synuclein aggregation and spread.

Human Nmnat1 Promotes Autophagic Clearance of Amyloid Plaques in a Drosophila Model of Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disease characterized by irreversible cognitive decline with limited therapeutic approaches. We characterized a Drosophila model of amyloid pathology that expresses human amyloid-beta precursor protein (APP⁶⁹⁵) and β-site APP cleaving enzyme (BACE) in the nervous system. Our model recapitulates in vivo the age-dependent accumulation of BACE-derived C-terminal fragment (CTF) and amyloid plaques in the brain, one of the key pathological hallmarks of AD. Using this model, we assessed the effects on plaque formation of Nicotinamide mononucleotide adenylyltransferase (Nmnat), an evolutionarily conserved nicotinamide adenine dinucleotide (NAD⁺) synthase involved in cellular metabolism and neuroprotection. We compared the effects of overexpression of Drosophila Nmnat (dNmnat), human Nmnat1 (hNmnat1), human Nmnat2 (hNmnat2), and human Nmnat3 (hNmnat3), and observed that hNmnat1 has the highest efficacy in reducing amyloid aggregation and APP-CTF accumulation. Interestingly, we demonstrated that overexpression of hNmnat1 reduces amyloid plaques by promoting autophagic clearance. Our findings uncover a role of hNmnat1 in amyloid clearance and suggest an exciting neuroprotective potential of hNmnat1 in amyloid pathology.

Liquiritigenin Inhibits Lipid Accumulation in 3T3-L1 Cells via mTOR-Mediated Regulation of the Autophagy Mechanism

Liquiritigenin (LQG) is a natural flavonoid from the herb Glycyrrhiza uralensis Fisch that exhibits multiple biological activities. However, its specific role in antiobesity and its related underlying molecular mechanisms remain unknown. The primary purpose of this study is to explore the effects and regulatory mechanisms of LQG on lipid accumulation in 3T3-L1 adipocytes. The results show that LQG significantly reduced triglyceride levels and downregulated the expression of transcription factors such as CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ) in 3T3-L1 adipocytes. Additionally, the expression of sterol-regulatory element-binding protein 1c (SREBP1c), acetyl-CoA carboxylase 1 (ACC1), and fatty acid synthase (FASN) involved in lipogenesis was reduced by treatment with LQG. The protein expression levels of light chain 3B (LC3B), autophagy-related protein 7 (ATG7) and p62 were also modulated by LQG, leading to the suppression of autophagy. Further, LQG activated the phosphorylation of the mammalian target of rapamycin (mTOR), the inhibition of which was followed by the restored expression of autophagy-related proteins. Pretreatment with an mTOR inhibitor also reverted the expression of several genes or proteins involved in lipid synthesis. These results suggest that LQG inhibited lipid accumulation via mTOR-mediated autophagy in 3T3-L1 white adipocytes, indicating the role of LQG as a potential natural bioactive component for use in dietary supplements for preventing obesity.

Loss of miR-34 in Drosophila dysregulates protein translation and protein turnover in the aging brain

Aging is a risk factor for neurodegenerative disease, but precise mechanisms that influence this relationship are still under investigation. Work in Drosophila melanogaster identified the microRNA miR‐34 as a modifier of aging and neurodegeneration in the brain. MiR‐34 mutants present aspects of early aging, including reduced lifespan, neurodegeneration, and a buildup of the repressive histone mark H3K27me3. To better understand how miR‐34 regulated pathways contribute to age‐associated phenotypes in the brain, here we transcriptionally profiled the miR‐34 mutant brain. This identified that genes associated with translation are dysregulated in the miR‐34 mutant. The brains of these animals show increased translation activity, accumulation of protein aggregation markers, and altered autophagy activity. To determine if altered H3K27me3 was responsible for this proteostasis dysregulation, we studied the effects of increased H3K27me3 by mutating the histone demethylase Utx. Reduced Utx activity enhanced neurodegeneration and mimicked the protein accumulation seen in miR‐34 mutant brains. However, unlike the miR‐34 mutant, Utx mutant brains did not show similar altered autophagy or translation activity, suggesting that additional miR‐34‐targeted pathways are involved. Transcriptional analysis of predicted miR‐34 targets identified Lst8, a subunit of Tor Complex 1 (TORC1), as a potential target. We confirmed that miR‐34 regulates the 3’ UTR of Lst8 and identified several additional predicted miR‐34 targets that may be critical for maintaining proteostasis and brain health. Together, these results present novel understanding of the brain and the role of the conserved miRNA miR‐34 in impacting proteostasis in the brain with age.

Activation of the ubiquitin-proteasome system contributes to oculopharyngeal muscular dystrophy through muscle atrophy

Oculopharyngeal muscular dystrophy (OPMD) is a late-onset disorder characterized by progressive weakness and degeneration of specific muscles. OPMD is due to extension of a polyalanine tract in poly(A) binding protein nuclear 1 (PABPN1). Aggregation of the mutant protein in muscle nuclei is a hallmark of the disease. Previous transcriptomic analyses revealed the consistent deregulation of the ubiquitin-proteasome system (UPS) in OPMD animal models and patients, suggesting a role of this deregulation in OPMD pathogenesis. Subsequent studies proposed that UPS contribution to OPMD involved PABPN1 aggregation. Here, we use a Drosophila model of OPMD to address the functional importance of UPS deregulation in OPMD. Through genome-wide and targeted genetic screens we identify a large number of UPS components that are involved in OPMD. Half dosage of UPS genes reduces OPMD muscle defects suggesting a pathological increase of UPS activity in the disease. Quantification of proteasome activity confirms stronger activity in OPMD muscles, associated with degradation of myofibrillar proteins. Importantly, improvement of muscle structure and function in the presence of UPS mutants does not correlate with the levels of PABPN1 aggregation, but is linked to decreased degradation of muscle proteins. Oral treatment with the proteasome inhibitor MG132 is beneficial to the OPMD Drosophila model, improving muscle function although PABPN1 aggregation is enhanced. This functional study reveals the importance of increased UPS activity that underlies muscle atrophy in OPMD. It also provides a proof-of-concept that inhibitors of proteasome activity might be an attractive pharmacological approach for OPMD.

Oculopharyngeal muscular dystrophy (OPMD) is a genetic disease characterized by progressive weakness of specific muscles, leading to swallowing difficulties (dysphagia), eyelid drooping (ptosis) and walking difficulties at later stages. No drug treatments are currently available. OPMD is due to mutations in a nuclear protein called poly(A) binding protein nuclear 1 (PABPN1) that is involved in processing of different classes of RNAs in the nucleus. We have used an animal model of OPMD that we have developed in the fly Drosophila to investigate the role in OPMD of the ubiquitin-proteasome system, a pathway specialized in protein degradation. We report an increased activity of the ubiquitin-proteasome system that is associated with degradation of muscular proteins in the OPMD Drosophila model. We propose that higher activity of the ubiquitin-proteasome system leads to muscle atrophy in OPMD. Importantly, oral treatment of this OPMD animal model with an inhibitor of proteasome activity reduces muscle defects. A number of proteasome inhibitors are approved drugs used in clinic against cancers, therefore our results provide a proof-of-concept that inhibitors of proteasome might be of interest in future treatments of OPMD.

p62 works as a hub modulation in the ageing process

p62 (also known as SQSTM1) is widely used as a predictor of autophagic flux, a process that allows the degradation of harmful and unnecessary components through lysosomes to maintain protein homeostasis in cells. p62 is also a stress-induced scaffold protein that resists oxidative stress. The multiple domains in its structure allow it to be connected with a variety of vital signalling pathways, autophagy and the ubiquitin proteasome system (UPS), allowing p62 to play important roles in cell proliferation, apoptosis and survival. Recent studies have shown that p62 is also directly or indirectly involved in the ageing process. In this review, we summarize in detail the process by which p62 regulates ageing from multiple ageing-related signs with the aim of providing new insight for the study of p62 in ageing.

Modulation of muscle redox and protein aggregation rescues lethality caused by mutant lamins

Mutations in the human LMNA gene cause a collection of diseases called laminopathies, which includes muscular dystrophy and dilated cardiomyopathy. The LMNA gene encodes lamins, filamentous proteins that form a meshwork on the inner side of the nuclear envelope. How mutant lamins cause muscle disease is not well understood, and treatment options are currently limited. To understand the pathological functions of mutant lamins so that therapies can be developed, we generated new Drosophila models and human iPS cell-derived cardiomyocytes. In the Drosophila models, muscle-specific expression of the mutant lamins caused nuclear envelope defects, cytoplasmic protein aggregation, activation of the Nrf2/Keap1 redox pathway, and reductive stress. These defects reduced larval motility and caused death at the pupal stage. Patient-derived cardiomyocytes expressing mutant lamins showed nuclear envelope deformations. The Drosophila models allowed for genetic and pharmacological manipulations at the organismal level. Genetic interventions to increase autophagy, decrease Nrf2/Keap1 signaling, or lower reducing equivalents partially suppressed the lethality caused by mutant lamins. Moreover, treatment of flies with pamoic acid, a compound that inhibits the NADPH-producing malic enzyme, partially suppressed lethality. Taken together, these studies have identified multiple new factors as potential therapeutic targets for LMNA-associated muscular dystrophy.

Cell death and pathological findings of the spleen in COVID-19 patients

The coronavirus disease 2019(COVID-19) is recognized as systemic inflammatory response syndrome. It was demonstrated that a rapid increase of cytokines in the serum of COVID-19 patients is associated with the severity of disease. However, the mechanisms of the cytokine release are not clear. By using immunofluorescence staining we found that the number of CD11b positive immune cells including macrophages in the spleens of died COVID-19 patients, was significantly higher than that of the control patients. The incidence of apoptosis as measured by two apoptotic markers, TUNEL and cleaved caspase-3, in COVID-19 patients' spleen cells is higher than that in control patients. By double immunostaining CD11b or CD68 and SARS-CoV-2 spike protein, it was found that up to 67% of these immune cells were positive for spike protein, suggesting that viral infection might be associated with apoptosis in these cells. Besides, we also stained the autophagy-related molecules (p-Akt、p62 and BCL-2) in spleen tissues, the results showed that the number of positive cells was significantly higher in COVID-19 group. And compared with non-COVID-19 patients, autophagy may be inhibited in COVID-19 patients. Our research suggest that SARS-CoV-2 may result in a higher rate of apoptosis and a lower rate of autophagy of immune cells in the spleen of COVID-19 patients. These discoveries may increase our understanding of the pathogenesis of COVID-19.

Macroautophagy and normal aging of the nervous system: Lessons from animal models

Aging represents a cumulative form of cellular stress, which is thought to challenge many aspects of proteostasis. The non-dividing, long-lived neurons are particularly vulnerable to stress, and, not surprisingly, even normal aging is highly associated with a decline in brain function in humans, as well as in other animals. Macroautophagy is a fundamental arm of the proteostasis network, safeguarding proper protein turnover during different cellular states and against diverse cellular stressors. An intricate interplay between macroautophagy and aging is beginning to unravel, with the emergence of new tools, including those for monitoring autophagy in cultured neurons and in the nervous system of different organisms in vivo. Here, we review recent findings on the impact of aging on neuronal integrity and on neuronal macroautophagy, as they emerge from studies in invertebrate and mammalian models.

Biomarkers of Autophagy

Biomarkers (short for biological markers) are biological measures of a biological state. Autophagy biomarkers play an important role as an indicator of autophagy during normal physiological processes, pathogenic processes or pharmacological responses to drugs. In this chapter, some biomarkers of different types of autophagy, including macroautophagy, selective autophagy, chaperone-mediated autophagy, and microautophagy, as well as the lysosomal biomarkers are introduced. The described biomarkers may be used to detect the level of autophagy in cells or tissues in a dynamic, real-time, and quantitative manner. However, each biomarker has its specific significance and limitation. Therefore, the analysis of the autophagy level in cells or tissues through the detection of autophagy biomarkers should be carried out carefully.

UM-6 induces autophagy and apoptosis via the Hippo-YAP signaling pathway in cervical cancer

Melittin's non-specific cytotoxicity and hemolytic activity restrict its clinical use, but polypeptide modification is thoμght to be highly selective and well-tolerated. Here, we synthesized a novel antineoplastic peptide UM-6 based on melittin and explored the mechanism related to its anti-proliferation and metastasis on cervical cancer (CC). In the present study, we demonstrated that UM-6 inhibits viability of CC cell lines Caski and Hela in vitro by inducing apoptosis and autophagy with low toxicity to normal epithelial cells. UM-6 also triggers the Hippo signaling pathway, promoting cytoplasmic retention and phosphorylation-dependent degradation of YAP, as well as inhibiting YAP-TEAD binding and reducing transcriptional activity, suppressing downstream target gene expression. Injection of UM-6 in mice can significantly inhibit the growth of xenograft tumors, and greatly reduce the number, volume, and burden of abdominal tumors in the metastasis models without significant toxicity. These current results suggest that UM-6 has the potential to serve as a new anticancer drug candidate.

In vivo autophagy quantification: Measuring LC3 and P62 puncta in 3D image system from zebrafish larvae

Autophagy is a central pathway in maintaining cellular homeostasis through the recycling of damaged proteins and organelles. Detection of LC3 protein levels by immunofluorescence or western blot analysis is one of the most common ways to measure autophagy. For quantitative autophagy analysis, LC3 western blot analysis is commonly used, whereas immunostaining is used for qualitative autophagy analysis. However, zebrafish larvae have a lot of proteases that rapidly degrade LC3 protein in samples. P62 is another autophagy marker that bind to damaged proteins and can reflects autophagic status. This study demonstrates a fast and accurate way to quantify autophagy from LC3 and/or P62 immunostaining images. We used a three-dimensional analysis of whole-mount LC3 immunostaining images of zebrafish larvae. Counting LC3 and P62 punctate by two dimensions can be used as a qualitative method for the analysis of autophagy. However, here we demonstrate that 3D image analysis can be used as a quantitative, rapid tool for monitoring autophagy in zebrafish larvae and avoiding drawbacks of LC3 western blot analysis.

Perfluorotridecanoic acid inhibits fetal Leydig cell differentiation after in utero exposure in rats via increasing oxidative stress and autophagy

Perfluorotridecanoic acid (PFTrDA) is a long-chain perfluoroalkyl substance, and its effect on the differentiation of fetal Leydig cells remains unclear. The objective of this study is to explore the effect of in utero PFTrDA exposure on the differentiation of fetal Leydig cells and investigate its underlying mechanisms. Pregnant Sprague-Dawley female rats were daily administered by gavage of PFTrDA at doses of 0, 1, 5, and 10 mg/kg from gestational day 14 to 21. PFTrDA had no effect on the body weight of dams, but significantly reduced the body weight and anogenital distance of male pups at birth at a dose of 10 mg/kg. PFTrDA significantly decreased serum testosterone levels as low as 1 mg/kg. PFTrDA did not affect fetal Leydig cell number, but promoted abnormal aggregation of fetal Leydig cells at doses of 5 and 10 mg/kg. PFTrDA down-regulated the expression of Insl3, Lhcgr, Scarb1, Star, Hsd3b1, Cyp17a1, Nr5a1, and Dhh as well as their proteins. PFTrDA lowered the levels of antioxidants (SOD1, CAT, and GPX1), induced autophagy as shown by increased levels of LC3II and beclin1, and reduced the phosphorylation of mTOR. In conclusion, PFTrDA inhibits the differentiation of fetal Leydig cells in male pups after in utero exposure mainly through increasing oxidative stress and inducing autophagy.

NELF-A controls Drosophila healthspan by regulating heat-shock protein-mediated cellular protection and heterochromatin maintenance

NELF‐mediated pausing of RNA polymerase II (RNAPII) constitutes a crucial step in transcription regulation. However, it remains unclear how control release of RNAPII pausing can affect the epigenome and regulate important aspects of animal physiology like aging. We found that NELF‐A dosage regulates Drosophila healthspan: Halving NELF‐A level in the heterozygous mutants or via neuronal‐specific RNAi depletion improves their locomotor activity, stress resistance, and lifespan significantly. Conversely, NELF‐A overexpression shortens fly lifespan drastically. Mechanistically, lowering NELF‐A level facilitates the release of paused RNAPII for productive transcription of the heat‐shock protein (Hsp) genes. The elevated HSPs expression in turn attenuates the accumulation of insoluble protein aggregates, reactive oxidative species, DNA damage and systemic inflammation in the brains of aging NELF‐A depleted flies as compared to their control siblings. This pro‐longevity effect is unique to NELF‐A due to its higher expression level and more efficient pausing of RNAPII than other NELF subunits. Importantly, enhanced resistance to oxidative stress in NELF‐A heterozygous mutants is highly conserved such that knocking down its level in human SH‐SY5Y cells attenuates hydrogen peroxide‐induced DNA damage and apoptosis. Depleting NELF‐A reconfigures the epigenome through the maintenance of H3K9me2‐enriched heterochromatin during aging, leading to the repression of specific retrotransposons like Gypsy‐1 in the brains of NELF‐A mutants. Taken together, we showed that the dosage of neuronal NELF‐A affects multiple aspects of aging in Drosophila by regulating transcription of Hsp genes in the brains, suggesting that targeting transcription elongation might be a viable therapeutic strategy against age‐onset diseases like neurodegeneration.

Treatment with Bacterial Biologics Promotes Healthy Aging and Traumatic Brain Injury Responses in Adult Drosophila, Modeling the Gut-Brain Axis and Inflammation Responses

Drosophila are widely used to study neural development, immunity, and inflammatory pathways and processes associated with the gut-brain axis. Here, we examine the response of adult Drosophila given an inactive bacteriologic (IAB; proprietary lysate preparation of Lactobacillus bulgaricus, ReseT®) and a probiotic (Lactobacillus rhamnosus, LGG). In vitro, the IAB activates a subset of conserved Toll-like receptor (TLR) and nucleotide-binding, oligomerization domain-containing protein (NOD) receptors in human cells, and oral administration slowed the age-related decline of adult Drosophila locomotor behaviors. On average, IAB-treated flies lived significantly longer (+23%) and had lower neural aggregate profiles. Different IAB dosages also improved locomotor function and longevity profiles after traumatic brain injury (TBI) exposure. Mechanistically, short-term IAB and LGG treatment altered baseline nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κβ) signaling profiles in neural and abdominal tissues. Overall, at select dosages, IAB and LGG exposure has a positive impact on Drosophila longevity, neural aging, and mild traumatic brain injury (TBI)-related responses, with IAB showing greater benefit. This includes severe TBI (sTBI) responses, where IAB treatment was protective and LGG increased acute mortality profiles. This work shows that Drosophila are an effective model for testing bacterial-based biologics, that IAB and probiotic treatments promote neuronal health and influence inflammatory pathways in neural and immune tissues. Therefore, targeted IAB treatments are a novel strategy to promote the appropriate function of the gut-brain axis.

Homeostatic p62 levels and inclusion body formation in CHCHD2 knockout mice

Inactivation of constitutive autophagy results in the formation of cytoplasmic inclusions in neurones, but the relationship between impaired autophagy and Lewy bodies (LBs) remains unknown. α-Synuclein and p62, components of LBs, are the defining characteristic of Parkinson's disease (PD). Until now, we have analyzed mice models and demonstrated p62 aggregates derived from an autophagic defect might serve as 'seeds' and can potentially be a cause of LB formation. P62 may be the key molecule for aggregate formation. To understand the mechanisms of LBs, we analyzed p62 homeostasis and inclusion formation using PD model mice. In PARK22-linked PD, intrinsically disordered mutant CHCHD2 initiates Lewy pathology. To determine the function of CHCHD2 for inclusions formation, we generated Chchd2-knockout (KO) mice and characterized the age-related pathological and motor phenotypes. Chchd2 KO mice exhibited p62 inclusion formation and dopaminergic neuronal loss in an age-dependent manner. These changes were associated with a reduction in mitochondria complex activity and abrogation of inner mitochondria structure. In particular, the OPA1 proteins, which regulate fusion of mitochondrial inner membranes, were immature in the mitochondria of CHCHD2-deficient mice. CHCHD2 regulates mitochondrial morphology and p62 homeostasis by controlling the level of OPA1. Our findings highlight the unexpected role of the homeostatic level of p62, which is regulated by a non-autophagic system, in controlling intracellular inclusion body formation, and indicate that the pathologic processes associated with the mitochondrial proteolytic system are crucial for loss of DA neurones.

Effects of Trichinella spiralis and its excretory/secretory products on autophagy of host muscle cells in vivo and in vitro

Trichinella spiralis (T. spiralis) is a widely distributed pathogenic microorganism that causes trichinellosis, a disease that has the potential of causing severe harm to their host. Numerous studies have demonstrated that autophagy can be triggered by microbial infection, such as bacteria, viruses, protozoa, and parasitic helminths. However, it’s still unknown whether autophagy can facilitate host resistance to T. spiralis infection. The present study examined the role of autophagy in striated muscle cell transformation following infection with T. spiralis in BALB/c mice. Transmission electron microscopy (TEM) was used to detect the production of the host diaphragm autophagosome after T. spiralis infection, and changes in the protein and transcriptional levels of autophagic marker proteins were also detected. The significance of autophagy in T. spiralis infection, namely inhibition of T. spiralis growth, was preliminarily evaluated by conducting in vivo experiments using autophagy inhibitors. Besides, we studied the effect of excretory-secretory products (ES) of T. spiralis on autophagy of C2C12 myoblasts. The changes in protein and gene expression levels in autophagy-related pathways in vitro and in vivo were measured as further evidence. The results showed that T. spiralis infection induced autophagy in the host muscle cells. Meanwhile, ES inhibited autophagy of myoblasts in vitro, but this did not affect the cell viability. The upregulation and downregulation of autophagy-related factors in skeletal muscle cells may indicate an adaptive mechanism providing a comfortable niche for the parasite.

Autophagy, a intracellular degradation system, is a kind of unique phenomenon in eukaryotic cells. The commonly referred autophagy is the process of forming autophagosomes by wrapping the cytoplasmic components with double-membrane structure, and then fusing with lysosomes to degrade the internal substances of the cell. Autophagy can be induced by various pathogens including parasites. When the body is infected with intracellular parasites, the host cell can remove the parasites by autophagy. However, parasites have also evolved defence mechanisms that use autophagy in host cells to promote growth. These can be seen in some intracellular parasitic infections such as Toxoplasma gondii and Plasmodium. Although the role of autophagy in other parasitic infections has been revealed, it remains unclear whether autophagy is involved in the invasion process by Trichinella. We investigated the role of Trichinella infection on host muscle cells autophagy and the effect of autophagosome formation on the survival of T. spiralis. Understanding the role of autophagy in the interaction between parasitic infection and host cell is of great significance for the prevention and treatment of Trichinella infection and the development of anti-parasite drugs.

Inhibition of Ref(2)P, the Drosophila homologue of the p62/SQSTM1 gene, increases lifespan and leads to a decline in motor function

Objective

Sequestosome 1 (p62/SQSTM1) is a multifunctional scaffold/adaptor protein encoded by the p62/SQSTM1 gene with function in cellular homeostasis. Mutations in the p62/SQSTM1 gene have been known to be associated with patients with amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Parkinson disease (PD). The aim of the present study was to create a novel model of human neurogenerative disease in Drosophila melanogaster by altering the expression of Ref(2)P, the Drosophila orthologue of the human p62/SQSTM1 gene. Ref(2)P expression was altered in all neurons, the dopaminergic neurons and in the motor neurons, with longevity and locomotor function assessed over time.

Results

Inhibition of Ref(2)P resulted in a significantly increased median lifespan in the motor neurons, followed by a severe decline in motor skills. Inhibition of Ref(2)P in the dopaminergic neurons resulted in a significant, but minimal increase in median lifespan, accompanied by a drastic decline in locomotor function. Inhibition of Ref(2)P in the ddc-Gal4-expressing neurons resulted in a significant increase in median lifespan, while dramatically reducing motor function.

Tumor-intrinsic and -extrinsic (immune) gene signatures robustly predict overall survival and treatment response in high grade serous ovarian cancer patients

In the present study, we developed a transcriptomic signature capable of predicting prognosis and response to primary therapy in high grade serous ovarian cancer (HGSOC). Proportional hazard analysis was performed on individual genes in the TCGA RNAseq data set containing 229 HGSOC patients. Ridge regression analysis was performed to select genes and develop multigenic models. Survival analysis identified 120 genes whose expression levels were associated with overall survival (OS) (HR = 1.49-2.46 or HR = 0.48-0.63). Ridge regression modeling selected 38 of the 120 genes for development of the final Ridge regression models. The consensus model based on plurality voting by 68 individual Ridge regression models classified 102 (45%) as low, 23 (10%) as moderate and 104 patients (45%) as high risk. The median OS was 31 months (HR = 7.63, 95% CI = 4.85-12.0, P < 1.0-10) and 77 months (HR = ref) in the high and low risk groups, respectively. The gene signature had two components: intrinsic (proliferation, metastasis, autophagy) and extrinsic (immune evasion). Moderate/high risk patients had more partial and non-responses to primary therapy than low risk patients (odds ratio = 4.54, P < 0.001). We concluded that the overall survival and response to primary therapy in ovarian cancer is best assessed using a combination of gene signatures. A combination of genes which combines both tumor intrinsic and extrinsic functions has the best prediction. Validation studies are warranted in the future.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

Degradation of arouser by endosomal microautophagy is essential for adaptation to starvation in Drosophila

Drosophila EPS8-family protein Arouser is constitutively degraded by endosomal microautophagy; its stabilisation upon starvation is essential to the animal adaptation and survival.

Hunger drives food-seeking behaviour and controls adaptation of organisms to nutrient availability and energy stores. Lipids constitute an essential source of energy in the cell that can be mobilised during fasting by autophagy. Selective degradation of proteins by autophagy is made possible essentially by the presence of LIR and KFERQ-like motifs. Using in silico screening of Drosophila proteins that contain KFERQ-like motifs, we identified and characterized the adaptor protein Arouser, which functions to regulate fat storage and mobilisation and is essential during periods of food deprivation. We show that hypomorphic arouser mutants are not satiated, are more sensitive to food deprivation, and are more aggressive, suggesting an essential role for Arouser in the coordination of metabolism and food-related behaviour. Our analysis shows that Arouser functions in the fat body through nutrient-related signalling pathways and is degraded by endosomal microautophagy. Arouser degradation occurs during feeding conditions, whereas its stabilisation during non-feeding periods is essential for resistance to starvation and survival. In summary, our data describe a novel role for endosomal microautophagy in energy homeostasis, by the degradation of the signalling regulatory protein Arouser.

Dexmedetomidine Ameliorates Hippocampus Injury and Cognitive Dysfunction Induced by Hepatic Ischemia/Reperfusion by Activating SIRT3-Mediated Mitophagy and Inhibiting Activation of the NLRP3 Inflammasome in Young Rats

Hepatic ischemia-reperfusion (HIR) has been proven to trigger oxidative stress and pyroptosis in the hippocampus. Sirtuin 3 (SIRT3) is an essential mitochondrial protein deacetylase regulating oxidative stress and mitophagy. Dexmedetomidine (Dex) has been demonstrated to confer neuroprotection in different brain injury models. However, whether the protective effects of Dex following HIR are orchestrated by activation of SIRT3-mediated mitophagy and inhibition of NOD-like receptor protein 3 (NLRP3) inflammasome activation remains unknown. Herein, two-week-old rats were treated with Dex or a selective SIRT3 inhibitor (3-TYP)/autophagy inhibitor (3-MA) and then subjected to HIR. The results revealed that Dex treatment effectively attenuated neuroinflammation and cognitive deficits via upregulating SIRT3 expression and activity. Furthermore, Dex treatment inhibited the activation of NLRP3 inflammasome, while 3-TYP and 3-MA eliminated the protective effects of Dex, suggesting that SIRT3-mediated mitophagy executes the protective effects of Dex. Moreover, 3-TYP treatment downregulated the expression level of SIRT3 downstream proteins: forkhead-box-protein 3α (FOXO3α), superoxide dismutase 2 (SOD2), peroxiredoxin 3 (PRDX3), and cyclophilin D (CYP-D), which were barely influenced by 3-MA treatment. Notably, both 3-TYP and 3-MA were able to offset the antioxidative and antiapoptosis effects of Dex, indicating that SIRT3-mediated mitophagy may be the last step and the major pathway executing the neuroprotective effects of Dex. In conclusion, Dex inhibits HIR-induced NLRP3 inflammasome activation mainly by triggering SIRT3-mediated mitophagy.

Single-cell analysis of autophagy activity in normal and de novo transformed human mammary cells

Assessment of autophagy activity has historically been limited to investigations of fixed tissue or bulk cell populations. To address questions of heterogeneity and relate measurements to functional properties of viable cells isolated from primary tissue, we created a lentiviral (RFP-GFP-MAP1LC3B) vector that allows the autophagosome and autolysosome content of transduced cells to be monitored at the single-cell level. Use of this strategy to analyze purified subsets of normal human mammary cells showed that both the luminal progenitor-containing (LP) subset and the basal cells (BCs) display highly variable but overall similar autophagic flux activity despite differences suggested by measurements of the proteins responsible (i.e., LC3B, ATG7 and BECLIN1) in bulk lysates. Autophagosome content was also highly variable in the clonogenic cells within both the LPs and BCs, but the proliferative response of the BCs was more sensitive to autophagy inhibition. In addition, use of this vector showed cells with the lowest autophagosome content elicited the fastest tumor growth in 2 different models of human mammary tumorigenesis. These results illustrate the utility of this vector to define differences in the autophagy properties of individual cells in primary tissue and couple these with their responses to proliferative and oncogenic stimuli.