Autophagy signal transduction by ATG proteins: from hierarchies to networks

The regulatory mechanisms of mitophagy and oxidative stress in androgenetic alopecia

Androgenetic alopecia (AGA), the most common type of non-scarring hair loss in dermatology, result from a multifaceted interplay of genetic susceptibility, abnormal androgen metabolism, and dysregulation within the follicular microenvironment. Recent studies have highlighted the crucial roles of mitophagy and oxidative stress in the pathogenesis and progression of AGA. Mitophagy, a selective process by which damaged mitochondria are eliminated, is essential for maintaining cellular energy metabolism homeostasis and redox balance. In contrast, oxidative stress results from excessive accumulation of reactive oxygen species (ROS), which induces cellular damage and accelerates disease progression. The disruption of the dynamic balance between mitophagy and oxidative stress is increasingly recognized as a key factor in the development and exacerbation of AGA. Despite initial studies elucidating the interaction between these two processes, the precise molecular mechanisms and regulatory networks governing AGA remain insufficiently understood. This review aims to systematically synthesize the latest findings concerning the interplay between mitophagy and oxidative stress in AGA. By examining their roles in the disease's onset and progression, we identify potential therapeutic targets for intervention. Additionally, we discuss relevant signaling pathways and cellular mechanisms, evaluating the therapeutic potential of targeting mitophagy and oxidative stress for the treatment of AGA.

Skeletal and dental tissue mineralization: The potential role of the endoplasmic reticulum/Golgi complex and the endolysosomal and autophagic transport systems

This paper presents a review of the potential role of the endoplasmic reticulum/Golgi complex and intracellular vesicles in mediating events leading to or associated with vertebrate tissue mineralization. The possible importance of these organelles in this process is suggested by observations that calcium ions accumulate in the tubules and lacunae of the endoplasmic reticulum and Golgi. Similar levels of calcium ions (approaching millimolar) are present in vesicles derived from endosomes, lysosomes and autophagosomes. The cellular level of phosphate ions in these organelles is also high (millimolar). While the source of these ions for mineral formation has not been identified, there are sound reasons for considering that they may be liberated from mitochondria during the utilization of ATP for anabolic purposes, perhaps linked to matrix synthesis. Published studies indicate that calcium and phosphate ions or their clusters contained as cargo within the intracellular organelles noted above lead to formation of extracellular mineral. The mineral sequestered in mitochondria has been documented as an amorphous calcium phosphate. The ion-, ion cluster- or mineral-containing vesicles exit the cell in plasma membrane blebs, secretory lysosomes or possibly intraluminal vesicles. Such a cell-regulated process provides a means for the rapid transport of ions or mineral particles to the mineralization front of skeletal and dental tissues. Within the extracellular matrix, the ions or mineral may associate to form larger aggregates and potential mineral nuclei, and they may bind to collagen and other proteins. How cells of hard tissues perform their housekeeping and other biosynthetic functions while transporting the very large volumes of ions required for mineralization of the extracellular matrix is far from clear. Addressing this and related questions raised in this review suggests guidelines for further investigations of the intracellular processes promoting the mineralization of the skeletal and dental tissues.

Effects of Huoxue Chubi decoction on protein kinase B-mammalian target of rapamycin autophagy pathway in scleroderma Balb/c model mice

OBJECTIVE

To explore the mechanisms by which Huoxue Chubi decoction (, HXCB) affects the protein kinase B (Akt)-mammalian target of rapamycin (mTOR) autophagy pathway in scleroderma Balb/c model mice.

METHODS

A scleroderma model was established in male Balb/c mice, followed by daily administration of HXCB (4.6, 2.3 and 1.15 g·kg-1·d-1) for 4 weeks. Bodyweight, epidermal and dermal thickness, dermal collagen levels, cutaneous reactive oxygen species (ROS) levels, Akt, Phosphorylated Akt (p-Akt), mTOR, Phosphorylated mTOR (p-mTOR), B-celllymphoma-2-interacting myosin-like coiled-coil protein 1 (Beclin-1) and microtubule-associated protein A/B-light chain 3 (LC3) protein and messenger ribonucleic acid (mRNA) expression were assessed.

RESULTS

HXCB treatment significantly reduced epidermal and dermal thickness, dermal collagen levels, ROS levels and the mRNA and protein expression of factors in the Akt-mTOR signaling pathway compared to the scleroderma model group. Conversely, mice body weight and autophagy factors Beclin-1 and LC3 were significantly increased in mice receiving HXCB treatment. Moreover, finally, ROS expression positively correlated with skin thickness, collagen contents and the mRNA expression levels of Akt, while the protein and mRNA expression levels of Akt-mTOR pathway-related factors were inversely correlated with the protein and mRNA expression of Beclin-1 and LC3.

CONCLUSION

HXCB can regulate autophagy by invigorating Qiand promoting blood circulation, thereby reducing blood stasis, facilitating new tissue generation, and contributing to scleroderma treatment. This effect may be attributed to the promotion of autophagy and enhancement of collagen degradation through the reduction of tissue oxidative stress elicited by HXCB.

Autophagy and Programmed Cell Death Modalities Interplay in HIV Pathogenesis

Human immunodeficiency virus (HIV) infection continues to be a major global health challenge, affecting 38.4 million according to the Joint United Nations Program on HIV/AIDS (UNAIDS) at the end of 2021 with 1.5 million new infections. New HIV infections increased during the 2 years after the COVID-19 pandemic. Understanding the intricate cellular processes underlying HIV pathogenesis is crucial for developing effective therapeutic strategies. Among these processes, autophagy and programmed cell death modalities, including apoptosis, necroptosis, pyroptosis, and ferroptosis, play pivotal roles in the host-virus interaction dynamics. Autophagy, a highly conserved cellular mechanism, acts as a double-edged sword in HIV infection, influencing viral replication, immune response modulation, and the fate of infected cells. Conversely, apoptosis, a programmed cell death mechanism, is a critical defense mechanism against viral spread and contributes to the depletion of CD4+ T cells, a hallmark of HIV/AIDS progression. This review aims to dissect the complex interplay between autophagy and these programmed cell death modalities in HIV-induced pathogenesis. It highlights the molecular mechanisms involved, their roles in viral persistence and immune dysfunction, and the challenges posed by the viral reservoir and drug resistance, which continue to impede effective management of HIV pathology. Targeting these pathways holds promise for novel therapeutic strategies to mitigate immune depletion and chronic inflammation, ultimately improving outcomes for individuals living with HIV.

RNA N6-methyladenosine modification in arthritis: New insights into pathogenesis

The commonest type of eukaryotic RNA modification, N6-methyladenosine (m6A), has drawn increased scrutiny in the context of pathological functioning as well as relevance in determination of RNA stability, splicing, transportation, localization, and translation efficiency. The m6A modification plays an important role in several types of arthritis, especially osteoarthritis and rheumatoid arthritis. Recent studies have reported that m6A modification regulates arthritis pathology in cells, such as chondrocytes and synoviocytes via immune responses and inflammatory responses through functional proteins classified as writers, erasers, and readers. The aim of this review was to highlight recent advances relevant to m6A modification in the context of arthritis pathogenesis and detail underlying molecular mechanisms, regulatory functions, clinical applications, and future perspectives of m6A in arthritis with the aim of providing a foundation for future research directions.

20(R)-ginsenoside Rg3 protects against focal cerebral ischemia‒reperfusion injury by suppressing autophagy via PI3K/Akt/mTOR signaling pathway

OBJECTIVE

This study aimed to investigate the effect of 20(R)-ginsenoside Rg3 on autophagy induced by cerebral ischemia‒reperfusion injury (CIRI) in rats and explore its regulation of the PI3K/Akt signaling pathway.

METHODS

Middle cerebral artery occlusion/reperfusion (MCAO/R) in male rats was injected intraperitoneally with 20(R)-ginsenoside Rg3 (5, 10, 20 mg/kg) 12 h before modeling, 2 h after ischemia and 12 h after reperfusion. Neurobehavioral and neuronal morphological changes were detected 24 h after brain I/R. In vitro, the OGD/R-induced injury model is replicated in PC12 cells and different concentrations of 20(R)-ginsenoside Rg3 are administered to observe its effects on cell viability and autophagy and PI3K/Akt/mTOR-related protein expression.

RESULTS

Our findings suggest that treatment with 20 mg/kg 20(R)-ginsenoside Rg3 significantly attenuated the neuronal injury, as evidenced by a decreased number of damaged neurons, reduced dissolution of Nissl corpuscles, a fewer autophagosomes, and downregulated expression of Beclin1 and LC3-II/I compared with the MCAO/R group. Furthermore, 20(R)-ginsenoside Rg3 treatment significantly upregulated the expression of p62, p-PI3K, p-AKT, and p-mTOR. In vitro, 20(R)-ginsenoside Rg3 significantly improved the survival rate of cells following OGD/R and markedly attenuated the LY294002 and OGD/R-induced upregulation of Beclin1 and LC3 gene expression. Moreover, 20(R)-ginsenoside Rg3 could rescued the LY294002 and OGD/R-induced downregulation of p62, p-PI3K, p-AKT, and p-mTOR expression.

CONCLUSIONS

20(R)-ginsenoside Rg3 attenuates neuronal injury and motor dysfunction following ischemia-reperfusion by inhibiting the activation of autophagy, and its mechanism is related to the upregulation of the PI3K/Akt/mTOR signaling pathway.

METTL3 regulates autophagy of hypoxia-induced cardiomyocytes by targeting ATG7

N6-methyladenosine (m6A) mRNA modification is the most common mRNA internal modification in eukaryotes, which participates in a variety of biological processes. However, the role of m6A methylation in regulating autophagy induced by ischemia and hypoxia remains to be widely investigated. Here, we investigated the impact of METTL3, a key m6A methyltransferase, on the autophagy regulation in ischemic and hypoxic cardiomyocytes, as well as in mice following acute myocardial infarction (AMI). METTL3 negatively regulated autophagy in cardiomyocytes under ischemia and hypoxia conditions. Silencing METTL3 enhanced autophagy and mitigated cardiomyocyte injury, whereas overexpression of METTL3 exerted the opposite effect. Mechanistically, METTL3 methylated ATG7 mRNA, a crucial autophagy-related gene, leads to the recruitment of the m6A-binding protein YTHDF2. Subsequently, YTHDF2 facilitated the degradation of ATG7 mRNA, consequently inhibiting autophagy and exacerbating cellular damage. Our study shed light on the pivotal role of METTL3-mediated m6A modification in the regulation of autophagy during AMI, providing novel insights into the functional significance of m6A methylation and its regulatory mechanisms.

Atg2 controls Drosophila hematopoiesis through the PVR/TOR signaling pathways

The hematopoietic system of Drosophila is a well-established genetic model for studying hematopoiesis mechanisms, which are strictly regulated by multiple signaling pathways. Autophagy-related 2 (Atg2) protein is involved in autophagosome formation through its lipid transfer function; however, other functions in animal development, especially the role of Atg2 in maintaining hematopoietic homeostasis, are unclear. Here, we show that Atg2 knockdown in the cortical zone (CZ) induced the proliferation and differentiation of mature plasmatocytes and disrupted progenitor maintenance in the medullary zone (MZ). We also observed the differentiation of lamellocytes among circulating hemocytes and in the lymph gland, which is rarely observed in healthy larvae. The above results on hematopoiesis disorders are due to Atg2 regulating the Drosophila PDGF/VEGF receptor (PVR) and target of rapamycin (TOR) in the CZ of lymph gland. In conclusion, we identified Atg2 as a previously undescribed regulator of hematopoiesis. Understanding the mechanism of maintenance of hematopoietic homeostasis in Drosophila will help us better evaluate human blood disorder-related diseases.

Review of research progress on different modalities of Macrophage death in Mycobacterium leprae infection

Leprosy, caused by Mycobacterium leprae (M. leprae), is a chronic infectious disease primarily affecting the skin and peripheral nerves. The interaction between M. leprae and macrophages, its primary host cell, plays a critical role in disease progression. This review explores the various forms of macrophage cell death induced by M. leprae infection, including apoptosis, autophagy, necroptosis, pyroptosis, ferroptosis and necrosis. The regulation and implications of these cell death pathways on the host immune response are discussed. Apoptosis and autophagy are highlighted as mechanisms that may limit M. leprae proliferation, while necroptosis and pyroptosis contribute to inflammation and immune response. Notably, recent studies have identified CYBB-mediated ferroptosis as essential for macrophages infected with M. leprae to polarize towards the M2 phenotype, facilitating immune evasion by the pathogen. This review underscores the complexity of macrophage cell death in leprosy, and summarize their corresponding molecular mechanisms and potential impact on the host immunity.

KMT2A regulates the autophagy-GATA4 axis through METTL3-mediated m6A modification of ATG4a to promote NPCs senescence and IVDD progression

Intervertebral disc degeneration (IVDD), a disease associated with ageing, is characterised by a notable increase in senescent nucleus pulposus cells (NPCs) as IVDD progresses. However, the specific mechanisms that regulate the senescence of NPCs remain unknown. In this study, we observed impaired autophagy in IVDD-NPCs, which contributed to the upregulation of NPCs senescence and the senescence-associated secretory phenotype (SASP). The dysregulated SASP disrupted NPCs viability and initiated extracellular matrix degradation. Conversely, the restoration of autophagy reversed the senescence phenotype by inhibiting GATA binding protein 4 (GATA4). Moreover, we made the novel observation that a cross-talk between histone H3 lysine 4 trimethylation (H3K4me3) modification and N6-methyladenosine(m6A)-methylated modification regulates autophagy in IVDD-NPCs. Mechanistically, lysine methyltransferase 2A (KMT2A) promoted the expression of methyltransferase-like 3 (METTL3) through H3K4me3 modification, whereas METTL3-mediated m6A modification reduced the expression of autophagy-associated 4a (ATG4a) by attenuating its RNA stability, leading to autophagy damage in NPCs. Silencing KMT2A and METTL3 enhanced autophagic flux and suppressed SASP expression in IVDD-NPCs. Therefore, targeting the H3K4me3-regulated METTL3/ATG4a/GATA4 axis may represent a promising new therapeutic strategy for IVDD.

Berberine and Lung Cancer: From Pure Form to Its Nanoformulations

Lung cancer is the most fatal cancer worldwide. The etiology of lung cancer has yet to be fully characterized. Smoking and air pollution are several risk factors for lung cancer. Berberine, an isoquinoline alkaloid, is an antihyperglycemic, antidepressant, antioxidative, anti-inflammatory, and anticancer compound. Evidence substantiates that berberine has antitumor effects, exerting its effects by targeting a variety of cellular and molecular processes, such as apoptosis, autophagy, cell cycle arrest, migration, and metastasis. Although the beneficial effects of berberine have been reported, some limitations including low bioavailability and absorption as well as poor aqueous solubility have hindered its clinical application. Nanotechnology and nanodelivery bioformulation approaches may bypass these limitations. In addition, the combination of berberine with other therapies has been shown to result in greater treatment efficacy for lung cancer. Herein, we summarize cellular and molecular pathways that are affected by berberine, its clinical efficacy upon various combinations, and the potential for nanotechnology in lung cancer therapy.

Early Diagnosis of AP5Z1/SPG48 Spastic Paraplegia: Case Report and Review of the Literature

Hereditary spastic paraplegias (HSPs) are a genetically heterogeneous group of neurodegenerative disorders clinically characterized by progressive lower limb spasticity with pyramidal weakness. Around a dozen potential molecular mechanisms are recognized. Childhood HSP is a significant diagnostic challenge in clinical practice. Mutations in AP5Z1, which are associated with spastic paraplegia type 48 (SPG48), are extremely rare and seldom described in children.We report the clinical, radiologic, and molecular studies performed in a child harboring novel biallelic mutations in AP5Z1.The child presented a neurodevelopmental disorder with slight lower limb pyramidal signs. Brain magnetic resonance imaging (MRI) showed minimal white matter changes in the frontal horns of the lateral ventricles and a normally shaped corpus callosum. Western blotting in cultured skin fibroblasts indicated reduced protein expression, which confirmed the genetic diagnosis and framed this as a case of protein reduction in a context of impaired autophagy.Our findings expand the spectrum of phenotypes associated with mutations in AP5Z1, highlighting their clinical and pathophysiologic overlap with lysosomal storage disorders. SPG48 should be considered in the differential diagnosis of neurodevelopmental disorders even when pyramidal signs are minimal and brain MRI not fully informative.

Potential of Edaravone Dexborneol in the treatment of cerebral ischemia: focus on cell death-related signaling pathways

Cerebral ischemia has the highest global rate of morbidity and mortality. It occurs when a sudden occlusion develops in the arterial system, and consequently some parts of the brain are deprived from glucose and oxygen due to the cessation of blood flow. The ensuing reperfusion of the ischemic area results in a cascade of pathological alternations like neuronal apoptosis by producing excessive reactive oxygen species (ROS), oxidative stress and neuroinflammation. Edaravone Dexborneol is a novel agent, comprised of Edaravone and Dexborneol in a 4:1 ratio. It has documented neuroprotective effects against cerebral ischemia injury. Edaravone Dexborneol improves neurobehavioral and sensorimotor function, cognitive function, brain edema, and blood-brain barrier (BBB) integrity in experimental models. It at dosages ranging between 0.375 and 15 mg/kg (from immediately after ischemia until the 28th post-ischemic days) has shown neuroprotective effects in experimental models of cerebral ischemia by inhibiting cell death-signaling pathways. For example, it inhibits apoptosis by increasing Bcl2, and reducing Bax and caspase-3 expression. Edaravone Dexborneol also inhibits pyroptosis by attenuating NF-κB/NLRP3/GSDMD signaling, as well as ferroptosis by activating the Nrf-2/HO-1/GPX4 signaling pathway. It also inhibits autophagy by targeting PI3K/Akt/mTOR signaling pathway. Here, we provide a review on the impacts of Edaravone Dexborneol on cerebral ischemia.

Mild heat shock at 40 °C increases levels of autophagy: Role of Nrf2

The exposure to low doses of stress induces an adaptive survival response that involves the upregulation of cellular defense systems such as heat shock proteins (Hsps), anti-apoptosis proteins, and antioxidants. Exposure of cells to elevated, non-lethal temperatures (39-41 °C) is an adaptive survival response known as thermotolerance, which protects cells against subsequent lethal stress such as heat shock (>41.5 °C). However, the initiating factors in this adaptive survival response are not understood. This study aims to determine whether autophagy can be activated by heat shock at 40 °C and if this response is mediated by the transcription factor Nrf2. Thermotolerant cells, which were developed during 3 h at 40 °C, were resistant to caspase activation at 42 °C. Autophagy was activated when cells were heated from 5 to 60 min at 40 °C. Levels of acidic vesicular organelles (AVOs) and autophagy proteins Beclin-1, LC3-II/LC3-I, Atg7, Atg5, Atg12-Atg5, and p62 were increased. When Nrf2 was overexpressed or depleted in cells, levels of AVOs and autophagy proteins were higher in unstressed cells, compared to the wild type. Stress induced by mild heat shock at 40 °C further increased levels of most autophagy proteins in cells with overexpression or depletion of Nrf2. Colocalization of p62 and Keap1 occurred. When Nrf2 levels are low, activation of autophagy would likely compensate as a defense mechanism to protect cells against stress. An improved understanding of autophagy in the context of cellular responses to physiological heat shock could be useful for cancer treatment by hyperthermia and the protective role of adaptive responses against environmental stresses.

Regulation of Autophagy Signaling Pathways by Ginseng Saponins: A Review

Ginseng saponins (ginsenosides), bioactive compounds derived from ginseng, are widely used natural products with potent therapeutic properties in the management of various ailments, particularly tumors, cardiovascular and cerebrovascular diseases, and immune system disorders. Autophagy, a highly regulated and multistep process involving the breakdown of impaired organelles and macromolecules by autophagolysosomes and autophagy-related genes (ATGs), has gained increasing attention as a potential target for ginsenoside-mediated disease treatment. This review aims to provide a comprehensive overview of recent research advances in the understanding of autophagy-related signaling pathways and the role of ginsenoside-mediated autophagy regulation. By delving into the intricate autophagy signaling pathways underpinning the pharmacological properties of ginsenosides, we highlight their therapeutic potential in addressing various conditions. Our findings serve as a comprehensive reference for further investigation into the medicinal properties of ginseng or ginseng-related products.

Activation of adenosine A2B receptor alleviates myocardial ischemia-reperfusion injury by inhibiting endoplasmic reticulum stress and restoring autophagy flux

Myocardial ischemia-reperfusion injury (MIRI) poses a significant threat to patients with coronary heart disease. Adenosine A2A receptors have been known as a protective role in MIRI by regulating autophagy, so we assumed that activation of adenosine A2B receptor (A2BAR) might exert a similar effect during MIRI and underlying mechanism be related to proteostasis maintenance as well. In situ hearts were subjected to 30 min of ischemia and 120 min of reperfusion (IR), while invitro cardiomyocytes from neonatal rats experienced 6 h of oxygen-glucose deprivation followed by 12 h of reoxygenation (OGDR). Initially, we observed that post-ischemia-reperfusion induced autophagy flux blockade and ERS both in vivo and in vitro, evident through the increased expression of p62, LC3II, and BIP, which indicated the deteriorated proteostasis. We used a selective A2BAR agonist, Bay 60-6583, to explore the positive effects of A2BAR on cardiomyocytes and found that A2BAR activation rescued damaged cardiac function and morphological changes in the IR group and improved frail cell viability in the OGDR group. The A2BAR agonist also alleviated the blockage of autophagic flux, coupled with augmented ERS in the IR/OGDR group, which was reassured by using an autophagy inhibitor chloroquine (CQ) and ERS inhibitor (4-PBA) in vitro. Additionally, considering cAMP/PKA as a well-known downstream effector of A2BAR, we utilized H89, a selective PKA inhibitor. We observed that the positive efficacy of Bay 60-6583 was inhibited by H89. Collectively, our findings demonstrate that the A2BAR/cAMP/PKA signaling pathway exerts a protective role in MIRI by mitigating impaired autophagic flux and excessive ERS.

Role of autophagy in ischemic stroke: insights from animal models and preliminary evidence in the human disease

Stroke represents a main cause of death and permanent disability worldwide. The molecular mechanisms underlying cerebral injury in response to the ischemic insults are not completely understood. In this article, we summarize recent evidence regarding the role of autophagy in the pathogenesis of ischemic stroke by reviewing data obtained in murine models of either transient or permanent middle cerebral artery occlusion, and in the stroke-prone spontaneously hypertensive rat. Few preliminary observational studies investigating the role of autophagy in subjects at high cerebrovascular risk and in cohorts of stroke patients were also reviewed. Autophagy plays a dual role in neuronal and vascular cells by exerting both protective and detrimental effects depending on its level, duration of stress and type of cells involved. Protective autophagy exerts adaptive mechanisms which reduce neuronal loss and promote survival. On the other hand, excessive activation of autophagy leads to neuronal cell death and increases brain injury. In conclusion, the evidence reviewed suggests that a proper manipulation of autophagy may represent an interesting strategy to either prevent or reduce brain ischemic injury.

Autophagy and senescence facilitate the development of antiestrogen resistance in ER positive breast cancer

Estrogen receptor positive (ER+) breast cancer is the most common breast cancer diagnosed annually in the US with endocrine-based therapy as standard-of-care for this breast cancer subtype. Endocrine therapy includes treatment with antiestrogens, such as selective estrogen receptor modulators (SERMs), selective estrogen receptor downregulators (SERDs), and aromatase inhibitors (AIs). Despite the appreciable remission achievable with these treatments, a substantial cohort of women will experience primary tumor recurrence, subsequent metastasis, and eventual death due to their disease. In these cases, the breast cancer cells have become resistant to endocrine therapy, with endocrine resistance identified as the major obstacle to the medical oncologist and patient. To combat the development of endocrine resistance, the treatment options for ER+, HER2 negative breast cancer now include CDK4/6 inhibitors used as adjuvants to antiestrogen treatment. In addition to the dysregulated activity of CDK4/6, a plethora of genetic and biochemical mechanisms have been identified that contribute to endocrine resistance. These mechanisms, which have been identified by lab-based studies utilizing appropriate cell and animal models of breast cancer, and by clinical studies in which gene expression profiles identify candidate endocrine resistance genes, are the subject of this review. In addition, we will discuss molecular targeting strategies now utilized in conjunction with endocrine therapy to combat the development of resistance or target resistant breast cancer cells. Of approaches currently being explored to improve endocrine treatment efficacy and patient outcome, two adaptive cell survival mechanisms, autophagy, and "reversible" senescence, are considered molecular targets. Autophagy and/or senescence induction have been identified in response to most antiestrogen treatments currently being used for the treatment of ER+ breast cancer and are often induced in response to CDK4/6 inhibitors. Unfortunately, effective strategies to target these cell survival pathways have not yet been successfully developed. Thus, there is an urgent need for the continued interrogation of autophagy and "reversible" senescence in clinically relevant breast cancer models with the long-term goal of identifying new molecular targets for improved treatment of ER+ breast cancer.

Protein turnover in pigs: A review of interacting factors

Protein turnover defines the balance between two continuous and complex processes of protein metabolism, synthesis and degradation, which determine their deposition in tissues. Although the liver and intestine have been studied extensively for their important roles in protein digestion, absorption and metabolism, the study of protein metabolism has focused mainly on skeletal muscle tissue to understand the basis for its growth. Due to the high adaptability of skeletal muscle, its protein turnover is greatly affected by different internal and external factors, contributing to carcass lean-yield and animal growth. Amino acid (AA) labelling and tracking using isotope tracer methodology, together with the study of myofiber type profiling, signal transduction pathways and gene expression, has allowed the analysis of these mechanisms from different perspectives. Positive stimuli such as increased nutrient availability in the diet (e.g., AA), physical activity, the presence of certain hormones (e.g., testosterone) or a more oxidative myofiber profile in certain muscles or pig genotypes promote increased upregulation of translation and transcription-related genes, activation of mTORC1 signalling mechanisms and increased abundance of satellite cells, allowing for more efficient protein synthesis. However, fasting, animal aging, inactivity and stress, inflammation or sepsis produce the opposite effect. Deepening the understanding of modifying factors and their possible interaction may contribute to the design of optimal strategies to better control tissue growth and nutrient use (i.e., protein and AA), and thus advance the precision feeding strategy.

Integrated transmission electron microscopy and proteomic analyses reveal the cytoarchitectural response to cucumber mosaic virus infection in tobacco

Cucumber mosaic virus (CMV) causes huge economic losses to agriculture every year; thus, understanding the mechanism of plant resistance to CMV is imperative. In this study, an integrated analysis of transmission electron microscopy (TEM) observations and proteomic results was used to identify cytoarchitectural differences in Nicotiana tabacum cv. NC82 (susceptible) and cv. Taiyan 8 (T.T.8; resistant) following infection with CMV. The TEM observations showed that the structure of the chloroplasts and mitochondria was severely damaged at the late stage of infection in NC82. Moreover, the chloroplast stroma and mitochondrial cristae were reduced and disaggregated. However, in T.T.8, organelle structure remained largely intact Selective autophagy predominated in T.T.8, whereas non-selective autophagy dominated in NC82, resembling cellular disorder. Proteomic analysis of T.T.8 revealed differentially expressed proteins (DEPs) mostly associated with photosynthesis, respiration, reactive oxygen species (ROS) scavenging, and cellular autophagy. Biochemical analyses revealed that ROS-related catalase, autophagy-related disulfide isomerase, and jasmonic acid and antioxidant secondary metabolite synthesis-related 4-coumarate:CoA ligase (Nt4CL) exhibited different trends and significant differences in expression in the two cultivars after CMV inoculation. Furthermore, mutant phenotyping verified that reduced Nt4CL expression impaired resistance in T.T.8. The identified DEPs are crucial for maintaining intracellular homeostatic balance and likely contribute to the mechanism of CMV resistance in tobacco. These findings increase our understanding of plant cytological mechanisms conferring resistance to CMV infection.

Crosstalk between myocardial autophagy and sterile inflammation in the development of heart failure

Heart failure, a leading driver of global mortality, remains a topic of intense contemporary research interest due to the prevailing unmet need in cardiometabolic therapeutics. Numerous mechanisms with the potential to influence the onset and development of heart failure remain incompletely understood. Firstly, myocardial autophagy, which involves lysosomal degradation of damaged cellular components, confers context-dependent beneficial and detrimental effects. Secondly, sterile inflammation may arise following cardiac stress and exacerbate the progression of heart failure. Inflammation changes in a temporal manner and its onset must be adequately resolved to limit progression of heart failure. Mitochondria are an important factor in contributing to sterile inflammation by releasing damage associated molecular patterns (DAMPs) including mitochondrial DNA (mtDNA). Accordingly, this is one reason why the selective autophagy of mitochondria to maintain optimal function is important in determining cardiac function. In this review, we examine the increasing evidence suggesting crosstalk between autophagy and sterile inflammation together with their role in the development of heart failure. In particular, this is exemplified in the preclinical models of ischaemia/reperfusion injury and pressure overload induced heart failure. We also highlight potential therapeutic approaches focusing on autophagy and addressing sterile inflammation, aiming to enhance outcomes in heart failure.

AMPKα is active in autophagy of endothelial cells in arsenic-induced vascular endothelial dysfunction by regulating mTORC1/p70S6K/ULK1

Cardiovascular disease (CVD) is the most common cause of death, environmental factors, such as arsenic, playing an important role in the progress of CVD. Vascular endothelial dysfunction (VED) is a crucial early feature for CVD, inorganic arsenic (iAs) can induce autophagy in various cells. However, the role of endothelial autophagy has rarely been studied in VED triggered by arsenic. Total of one hundred and twenty healthy male C57BL/6J mice weighing 18-22 g were randomly divided into an arsenic-exposure group and a control group for 3, 6, 9, and 12 weeks. The results showed that, independent of the exposure period, autophagy markers of p-ATG16L1 levels and Beclin 1 contents in the aortic arch endothelium increased significantly compared with those of the corresponding control group. And different exposure duration decreased NO contents in the serum significantly. Combined with the histological changes that endothelial injury aggravated gradually with the increasing exposure period, suggesting that under exposure to iAs over 9 weeks, VED was remarkably induced, and consistant high levels of endothelial autophagy may play an important role. Additionally, levels of p-AMPKα/AMPKα increased significantly and p-mTORC1/mTORC1 levels decreased remarkably in the aortic arch endothelium. Then, a NaAsO2-induced-VED in vitro model was used to explore the mechanism of arsenic-induced endothelial autophagy. Similarly, p-AMPKα/AMPKα level significantly increased, and p-mTORC1/mTORC1 level remarkably decreased induced by 30 μmol/L NaAsO2 in HUAECs. Further, an AMPK inhibitor (Compound C) pre-treatment prior to arsenic exposure reversed the increased autophagy level, and alleviated the endothelial dysfunction in HUVECs, as shown by the significant increase in the intracellular NO content and the cell vitality. Mechanistically, we revealed that AMPKα is active in autophagy of endothelial cells in arsenic-induced VED by regulating mTORC1/p70S6K/ULK1. The present study provide a new promising target for prevention and control arsenic-associated CVD.

The role and function of autophagy through signaling and pathogenetic pathways and lncRNAs in ovarian cancer

Lysosomal-driven autophagy is a tightly controlled cellular catabolic process that breaks down and recycles broken or superfluous cell parts. It is involved in several illnesses, including cancer, and is essential in preserving cellular homeostasis. Autophagy prevents DNA mutation and cancer development by actively eliminating pro-oxidative mitochondria and protein aggregates from healthy cells. Oncosuppressor and oncogene gene mutations cause dysregulation of autophagy. Increased autophagy may offer cancer cells a pro-survival advantage when oxygen and nutrients are scarce and resistance to chemotherapy and radiation. This finding justifies the use of autophagy inhibitors in addition to anti-neoplastic treatments. Excessive autophagy levels can potentially kill cells. The diagnosis and treatment of ovarian cancer present many difficulties due to its complexity and heterogeneity. Understanding the role of autophagy, a cellular process involved in the breakdown and recycling of cellular components, in ovarian cancer has garnered increasing attention in recent years. Of particular note is the increasing amount of data indicating a close relationship between autophagy and ovarian cancer. Autophagy either promotes or restricts tumor growth in ovarian cancer. Dysregulation of autophagy signaling pathways in ovarian cancers can affect the development, metastasis, and response to tumor treatment. The precise mechanism underlying autophagy concerning ovarian cancer remains unclear, as does the role autophagy plays in ovarian carcinoma. In this review, we tried to encapsulate and evaluate current findings in investigating autophagy in ovarian cancer.

ATAD1 inhibits hepatitis C virus infection by removing the viral TA-protein NS5B from mitochondria

ATPase family AAA domain-containing protein 1 (ATAD1) maintains mitochondrial homeostasis by removing mislocalized tail-anchored (TA) proteins from the mitochondrial outer membrane (MOM). Hepatitis C virus (HCV) infection induces mitochondrial fragmentation, and viral NS5B protein is a TA protein. Here, we investigate whether ATAD1 plays a role in regulating HCV infection. We find that HCV infection has no effect on ATAD1 expression, but knockout of ATAD1 significantly enhances HCV infection; this enhancement is suppressed by ATAD1 complementation. NS5B partially localizes to mitochondria, dependent on its transmembrane domain (TMD), and induces mitochondrial fragmentation, which is further enhanced by ATAD1 knockout. ATAD1 interacts with NS5B, dependent on its three internal domains (TMD, pore-loop 1, and pore-loop 2), and induces the proteasomal degradation of NS5B. In addition, we provide evidence that ATAD1 augments the antiviral function of MAVS upon HCV infection. Taken together, we show that the mitochondrial quality control exerted by ATAD1 can be extended to a novel antiviral function through the extraction of the viral TA-protein NS5B from the mitochondrial outer membrane.

Vascular Electrical Stimulation with Wireless, Battery-Free, and Fully Implantable Features Reduces Atherosclerotic Plaque Formation Through Sirt1-Mediated Autophagy

Electrical stimulation (ES) is a safe and effective procedure in clinical rehabilitation with few adverse effects. However, studies on ES for atherosclerosis (AS) are scarce because ES does not provide a long-term intervention for chronic disease processes. Battery-free implants and surgically mounted them in the abdominal aorta of high-fat-fed Apolipoprotein E (ApoE-/- ) mice are used, which are electrically stimulated for four weeks using a wireless ES device to observe changes in atherosclerotic plaques. Results showed that there is almost no growth of atherosclerotic plaque at the stimulated site in AopE-/- mice after ES. RNA-sequencing (RNA-seq) analysis of Thp-1 macrophages reveal that the transcriptional activity of autophagy-related genes increase substantially after ES. Additionally, ES reduces lipid accumulation in macrophages by restoring ABCA1- and ABCG1-mediated cholesterol efflux. Mechanistically, it is demonstrated that ES reduced lipid accumulation through Sirtuin 1 (Sirt1)/Autophagy related 5 (Atg5) pathway-mediated autophagy. Furthermore, ES reverse autophagic dysfunction in macrophages of AopE-/- mouse plaques by restoring Sirt1, blunting P62 accumulation, and inhibiting the secretion of interleukin (IL)-6, resulting in the alleviation of atherosclerotic lesion formation. Here, a novel approach is shown in which ES can be used as a promising therapeutic strategy for AS treatment through Sirt1/Atg5 pathway-mediated autophagy.

Bidirectional interplay between SARS-CoV-2 and autophagy

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as the causative agent of the recent COVID-19 pandemic, continues representing one of the main health concerns worldwide. Autophagy, in addition to its role in cellular homeostasis and metabolism, plays an important part for the host antiviral immunity. However, viruses including SARS-CoV-2 have evolved diverse mechanisms to not only overcome autophagy's antiviral pressure but also manipulate its machinery in order to enhance viral replication and propagation. Here, we discuss our current knowledge on the impact that autophagy exerts on SARS-CoV-2 replication, as well as the different counteracting measures that this virus has developed to manipulate autophagy's complex machinery. Some of the elements regarding this interplay may become future therapeutic targets in the fight against SARS-CoV-2.

Ficolin B secreted by alveolar macrophage exosomes exacerbates bleomycin-induced lung injury via ferroptosis through the cGAS-STING signaling pathway

Pathogenesis exploration and timely intervention of lung injury is quite necessary as it has harmed human health worldwide for years. Ficolin B (Fcn B) is a recognition molecule that can recognize a variety of ligands and play an important role in mediating the cell cycle, immune response, and tissue homeostasis in the lung. However, the role of Fcn B in bleomycin (BLM)-induced lung injury is obscure. This study aims to investigate the sources of Fcn B and its mechanism in BLM-induced lung injury. WT, Fcna-/-, and Fcnb-/- mice were selected to construct the BLM-induced lung injury model. Lung epithelial cells were utilized to construct the BLM-induced cell model. Exosomes that were secreted from alveolar macrophages (AMs) were applied for intervention by transporting Fcn B. Clinical data suggested M-ficolin (homologous of Fcn B) was raised in plasma of interstitial lung disease (ILD) patients. In the mouse model, macrophage-derived Fcn B aggravated BLM-induced lung injury and fibrosis. Fcn B further promoted the development of autophagy and ferroptosis. Remarkably, cell experiment results revealed that Fcn B transported by BLM-induced AMs exosomes accelerated autophagy and ferroptosis in lung epithelial cells through the activation of the cGAS-STING pathway. In contrast, the application of 3-Methyladenine (3-MA) reversed the promotion effect of Fcn B from BLM-induced AMs exosomes on lung epithelial cell damage by inhibiting autophagy-dependent ferroptosis. Meanwhile, in the BLM-induced mice model, the intervention of Fcn B secreted from BLM-induced AMs exosomes facilitated lung injury and fibrosis via ferroptosis. In summary, this study demonstrated that Fcn B transported by exosomes from AMs exacerbated BLM-induced lung injury by promoting lung epithelial cells ferroptosis through the cGAS-STING signaling pathway.

Newly uncovered biochemical and functional aspects of ferritin

Iron homeostasis is strictly regulated at both the systemic and cellular levels by complex mechanisms because of its indispensability and toxicity. Among the various iron-regulatory proteins, ferritin is the earliest discovered regulator of iron metabolism and is a molecule that safely retains excess intracellular iron in the cores of its shells. Two types of ferritin, cytosolic ferritin and mitochondrial ferritin (FTMT), have been identified in a range of organisms from plants to humans. FTMT was identified approximately 60 years after the discovery of cytosolic ferritin. Cytosolic ferritin expression is regulated in an iron-responsive manner. Recently, the molecular mechanisms of iron-dependent degradation of cytosolic ferritin or its secretion into serum have been clarified. FTMT, which shares a high degree of sequence homology with cytosolic ferritin, has distinct functions and is regulated in different ways from cytosolic ferritin. Although knowledge of the physiological role of FTMT is still incomplete, recent studies have shed light on the function and regulation of FTMT. The accumulating biological evidence of both ferritins has made it possible to deepen our knowledge about iron metabolism and its significance in diseases. In this review, we discuss the biological properties of both ferritins, focusing on their newly uncovered behaviors.

Deregulation of Autophagy and Apoptosis in Patients with Myelodysplastic Syndromes: Implications for Disease Development and Progression

(1) Background: Myelodysplastic neoplasms (MDSs) consist of a group of blood malignancies with a complex biological background. In this context, we investigated the role of autophagy and apoptosis in the pathogenesis and progression of MDSs. (2) Methods: To address this issue, we performed a systematic expression analysis on a total of 84 genes in patients with different types of MDSs (low/high risk of malignancy) versus healthy individuals. Furthermore, real-time quantitative PCR (qRT-PCR) was used to validate significantly upregulated or downregulated genes in a separate cohort of MDS patients and healthy controls. (3) Results: MDS patients were characterized by lower expression levels for a large series of genes involved in both processes compared to healthy individuals. Of importance, deregulation was more pronounced in patients with higher-risk MDS. Results from the qRT-PCR experiments displayed a high level of concordance with the PCR array, strengthening the relevance of our findings. (4) Conclusions: Our results indicate a clear effect of autophagy and apoptosis on MDS development, which becomes more pronounced as the disease progresses. The results from the present study are expected to assist in our understanding of the biological background of MDSs as well as in the identification of novel therapeutic targets.

Mitochondrial Dysfunction in the Cardio-Renal Axis

Cardiovascular disease (CVD) frequently complicates chronic kidney disease (CKD). The risk of all-cause mortality increases from 20% to 500% in patients who suffer both conditions; this is referred to as the so-called cardio-renal syndrome (CRS). Preclinical studies have described the key role of mitochondrial dysfunction in cardiovascular and renal diseases, suggesting that maintaining mitochondrial homeostasis is a promising therapeutic strategy for CRS. In this review, we explore the malfunction of mitochondrial homeostasis (mitochondrial biogenesis, dynamics, oxidative stress, and mitophagy) and how it contributes to the development and progression of the main vascular pathologies that could be affected by kidney injury and vice versa, and how this knowledge may guide the development of novel therapeutic strategies in CRS.

Japanese Flounder pol-miR-155 Is Involved in Edwardsiella tarda Infection via ATG3

MicroRNAs (miRNAs) are small RNA molecules that function in the post-transcriptionally regulation of the expression of diverse genes, including those involved in immune defense. Edwardsiella tarda can infect a broad range of hosts and cause severe disease in aquatic species, including Japanese flounder (Paralichthys olivaceus). In this study, we examined the regulation mechanism of a flounder miRNA, pol-miR-155, during the infection of E. tarda. Pol-miR-155 was identified to target flounder ATG3. Overexpression of pol-miR-155 or knockdown of ATG3 expression suppressed autophagy and promoted the intracellular replication of E. tarda in flounder cells. Overexpression of pol-miR-155 activated the NF-κB signaling pathway and further promoted the expression of downstream immune related genes of interleukin (IL)-6 and IL-8. These results unraveled the regulatory effect of pol-miR-155 in autophagy and in E. tarda infection.

Autophagy/Mitophagy Regulated by Ubiquitination: A Promising Pathway in Cancer Therapeutics

Autophagy is essential for organismal development, maintenance of energy homeostasis, and quality control of organelles and proteins. As a selective form of autophagy, mitophagy is necessary for effectively eliminating dysfunctional mitochondria. Both autophagy and mitophagy are linked with tumor progression and inhibition. The regulation of mitophagy and autophagy depend upon tumor type and stage. In tumors, mitophagy has dual roles: it removes damaged mitochondria to maintain healthy mitochondria and energy production, which are necessary for tumor growth. In contrast, mitophagy has been shown to inhibit tumor growth by mitigating excessive ROS production, thus preventing mutation and chromosomal instability. Ubiquitination and deubiquitination are important modifications that regulate autophagy. Multiple E3 ubiquitin ligases and DUBs modulate the activity of the autophagy and mitophagy machinery, thereby influencing cancer progression. In this review, we summarize the mechanistic association between cancer development and autophagy/mitophagy activities regulated by the ubiquitin modification of autophagic proteins. In addition, we discuss the function of multiple proteins involved in autophagy/mitophagy in tumors that may represent potential therapeutic targets.

Epibrassinolide impaired colon tumor progression and induced autophagy in SCID mouse xenograft model via acting on cell cycle progression without affecting endoplasmic reticulum stress observed in vitro

Epibrassinolide is a member of brassinosteroids with a polyhydroxysteroid structure similar to steroid hormones of vertebrates. It was shown that EBR decreased cell proliferation and induced apoptosis in different colon cancer cell lines without exerting a cytotoxic effect in epithelial fetal human colon cells. This finding highlighted the potential of epibrassinolide in clinical therapeutic setup. In our previous studies, we showed that epibrassinolide was able to induce apoptosis via endoplasmic reticulum stress. Recently, we also showed that endoplasmic reticulum and apoptotic stresses can be prevented via autophagic induction in non-cancerous epithelial or aggressive forms of cancer cells. Therefore, here in this study, we evaluated the anti-tumoral effect of epibrassinolide as well as the autophagy involvement in the aggressive forms of colon cancer cell lines as well as in vivo SCID mouse xenograft colon cancer model for the first time. For this purpose, SCID mouse model was used for subcutaneous injection of colon cancer cells in matrigel formulation. We found that autophagy is induced in both in vitro and in vivo models. Following tumor formation, SCID mice were treated daily with increasing concentrations of epibrassinolide for two weeks. Our findings showed that EBR inhibited the volume and diameter of the tumor in a dose-dependent manner by causing cell cycle arrest. Therefore our data suggest that epibrassinolide exerts a cytostatic effect on the agrressive form of colon cancer model in vivo, without affecting endoplasmic reticulum stress and the induction of autophagy might have role in this effect of epibrassinolide.

Deciphering the Function of New Therapeutic Targets and Prospective Biomarkers in the Management of Psoriasis

Psoriasis is an immune-mediated skin condition affecting people worldwide, presenting at any age, and leading to a substantial burden physically and mentally. The innate and adaptive immune systems interact intricately with the pathomechanisms that underlie disease. T cells can interact with keratinocytes, macrophages, and dendritic cells through the cytokines they secrete. According to recent research, psoriasis flare-ups can cause systemic inflammation and various other co-morbidities, including depression, psoriatic arthritis, and cardio-metabolic syndrome. Additionally, several auto-inflammatory and auto-immune illnesses may be linked to psoriasis. Although psoriasis has no proven treatment, care must strive by treating patients as soon as the disease surfaces, finding and preventing concurrent multimorbidity, recognising and reducing bodily and psychological distress, requiring behavioural modifications, and treating each patient individually. Biomarkers are traits that are assessed at any time along the clinical continuum, from the early stages of a disease through the beginning of treatment (the foundation of precision medicine) to the late stages of treatment (outcomes and endpoints). Systemic therapies that are frequently used to treat psoriasis provide a variety of outcomes. Targeted therapy selection, better patient outcomes, and more cost-effective healthcare would be made possible by biomarkers that reliably predict effectiveness and safety. This review is an attempt to understand the role of Antimicrobial peptides (AMP), Interleukin-38 (IL-38), autophagy 5 (ATG5) protein and squamous cell carcinoma antigen (SCCA) as biomarkers of psoriasis.

Neuroinflammation and Autophagy in Parkinson's Disease-Novel Perspectives

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder. It is characterized by the accumulation of α-Synuclein aggregates and the degeneration of dopaminergic neurons in substantia nigra in the midbrain. Although the exact mechanisms of neuronal degeneration in PD remain largely elusive, various pathogenic factors, such as α-Synuclein cytotoxicity, mitochondrial dysfunction, oxidative stress, and pro-inflammatory factors, may significantly impair normal neuronal function and promote apoptosis. In this context, neuroinflammation and autophagy have emerged as crucial processes in PD that contribute to neuronal loss and disease development. They are regulated in a complex interconnected manner involving most of the known PD-associated genes. This review summarizes evidence of the implication of neuroinflammation and autophagy in PD and delineates the role of inflammatory factors and autophagy-related proteins in this complex condition. It also illustrates the particular significance of plasma and serum immune markers in PD and their potential to provide a personalized approach to diagnosis and treatment.

Insulin and IGF-1 elicit robust transcriptional regulation to modulate autophagy in astrocytes

OBJECTIVE

Insulin is a principal metabolic hormone. It regulates a plethora of metabolic pathways in peripheral tissues. The highly homologous insulin-like growth factor 1 (IGF-1), on the other hand, is important for development and growth. Recent studies have shown that insulin and IGF-1 signaling plays fundamental roles in the brain. Loss of insulin or IGF-1 receptors in astrocytes leads to altered glucose handling, mitochondrial metabolism, neurovascular coupling, and behavioral abnormalities in mice. Here, we aim to investigate molecular mechanisms by which insulin and IGF-1 signaling regulates astrocyte functions.

METHODS

IR-flox and IRKO primary astrocytes were treated with 100 nM insulin or IGF-1 for 6 h, and their transcriptomes were analyzed. Astrocytes with either IR deletion, IGF1R deletion or both were used to examine receptor-dependent transcriptional regulations using qPCR. Additional immunoblotting and confocal imaging studies were performed to functionally validate pathways involved in protein homeostasis.

RESULTS

Using next-generation RNA sequencing, we show that insulin significantly regulates the expression of over 1,200 genes involved in multiple functional processes in primary astrocytes. Insulin-like growth factor 1 (IGF-1) triggers a similar robust transcriptional regulation in astrocytes. Thus, over 50% of the differentially expressed genes are regulated by both ligands. As expected, these commonly regulated genes are highly enriched in pathways involved in lipid and cholesterol biosynthesis. Additionally, insulin and IGF-1 induce the expression of genes involved in ribosomal biogenesis, while suppressing the expression of genes involved in autophagy, indicating a common role of insulin and IGF-1 on protein homeostasis in astrocytes. Insulin-dependent suppression of autophagy genes, including p62, Ulk1/2, and several Atg genes, is blunted only when both IR and IGF1R are deleted.

CONCLUSIONS

In summary, insulin and IGF-1 potently suppress autophagy in astrocytes through transcriptional regulation. Both IR and IGF1R can elicit ligand-dependent transcriptional suppression of autophagy. These results demonstrate an important role of astrocytic insulin/IGF-1 signaling on proteostasis. Impairment of this regulation in insulin resistance and diabetes may contribute to neurological complications related to diabetes.

TOLLIP Protein Expression Predicts Unfavorable Outcome in Renal Cell Carcinoma

Resistance to systemic therapy is one of the hallmarks of renal cell carcinoma (RCC). Recently, TOLLIP has emerged as a possible driver of autophagy and chemoresistance. We explored the relationship between primary and metastatic RCC tumor characteristics, patient survival, and TOLLIP expression. The tissue microarrays cohort contained 95 cores of the primary tumor, matched metastases, and matched adjacent tissues derived from 32 RCC patients. TOLLIP expression in tumor samples was evaluated using the H-score. All examined samples showed cytoplasmic TOLLIP expression, with a median value of 100 in primary tumors, 107.5 in metastases, and 220 in the control group. The expression was significantly higher in the normal adjacent tissues compared to primary or metastatic RCC (p < 0.05). We found a positive correlation between expressions of TOLLIP in the primary tumor and its metastases (p < 0.05; k = 0.48). TOLLIP expression significantly correlates with a lower overall survival rate (p = 0.047). TOLLIP functions as a ubiquitin-LC3 adaptor in the intracellular pathway associated with autophagy. Relative TOLLIP overexpression may augment autophagy-related signaling, limiting susceptibility to therapy. The blockade of TOLLIP physiological function seems to be a promising approach to overcoming resistance to systemic therapy.

Autophagy in adipogenesis: Molecular mechanisms and regulation by bioactive compounds

White adipose tissue expands rapidly due to increased adipocyte number (hyperplasia) and size (hypertrophy), which results in obesity. Adipogenesis is a process of the formation of mature adipocytes from precursor cells. Additionally, obesity-related metabolic complications, such as fatty liver and insulin resistance, are linked to adipogenesis. On the contrary, autophagy is a catabolic process; essential to maintain cellular homeostasis via the degradation or recycling of unnecessary or damaged components. Importantly, autophagy dictates obesity and adipogenesis. Hence, a clear understanding of how autophagy regulates adipogenesis is crucial for drug development and the prevention and treatment of obesity and its associated disorders, such as type 2 diabetes, cardiovascular disease, and cancer. In this review, we highlighted recent findings regarding the crosstalk between adipogenesis and autophagy, as well as the molecules involved. Furthermore, the review discussed how bioactive compounds regulate adipogenesis by manipulating autophagy and underlying molecular mechanisms. Based on in vitro and animal studies, we summarized the effects of bioactive compounds on adipogenesis and autophagy. Hence, human studies are necessary to validate the effectiveness and optimal dosage of these bioactive compounds.

Atrogin-1 knockdown inhibits the autophagy-lysosome system in mammalian and avian myotubes

Atrogin-1 plays an important role in ubiquitin-proteasome proteolysis in vertebrate skeletal muscles. Recently, atrogin-1 has been shown to be involved in the autophagy-lysosome system, another proteolytic system, in the murine and fish hearts and skeletal muscles. With the aim to elucidate the effect of atrogin-1 on the autophagy-lysosome system in mammalian and avian skeletal muscles, this study has examined the effects of atrogin-1 knockdown on autophagy-lysosome-related proteins in C2C12 and chicken embryonic myotubes. Using the levels of microtubule-associated protein light chain 3 (LC3)-II protein, it was confirmed that atrogin-1 knockdown blocked the autophagic flux in both the myotubes. In addition, atrogin-1 knockdown in C2C12 myotubes significantly decreased the level of autophagy-related gene (ATG)12-ATG5 conjugate, which is supposedly necessary for the fusion of autophagosomes and lysosomes. Atrogin-1 knockdown also resulted in downregulation of forkhead box O3, a transcription factor for ATG12. These data suggest that atrogin-1 is essential for the normal autophagy-lysosome system in the striated muscles of vertebrates.

Hormetic Heat Shock Enhances Autophagy through HSF1 in Retinal Pigment Epithelium Cells

To maintain homeostasis, cells have evolved stress-response pathways to cope with exogenous and endogenous stress factors. Diverse stresses at high doses may be detrimental, albeit low doses of stress, known as hormesis, can be beneficial. Upon exposure to stress, such as temperature rise, the conventional heat shock response (HSR) regulated by the heat shock transcription factor 1 (HSF1) facilitates refolding of misfolded proteins with the help of heat shock proteins (HSPs). However, the role and molecular mechanisms underlying the beneficial effects of HSR with other clearance processes, such as autophagy, remain poorly understood. In this study, human ARPE-19 cells, an in vitro model of retinal pigment epithelium, were treated with hormetic heat shock (HHS) and the autophagy expression profile was examined using quantitative PCR (qPCR), immunoblotting, immunoprecipitation, and immunofluorescence. We demonstrate that HHS enhances the expression of fundamental autophagy-associated genes in ARPE-19 cells through the activation of HSF1. HHS transiently increases the level of SQSTM1 and LC3B-II and activates autophagy. These findings reveal a role for autophagic HSF1-regulated functions and demonstrate the contribution of autophagy to hormesis in the HSR by improving proteostasis.

Comprehensive Comparison of Novel Bovine Leukemia Virus (BLV) Integration Sites between B-Cell Lymphoma Lines BLSC-KU1 and BLSC-KU17 Using the Viral DNA Capture High-Throughput Sequencing Method

Bovine leukemia virus (BLV) infects cattle and integrates into host DNA, causing enzootic bovine leukosis (EBL), an aggressive B-cell lymphoma. Here, we developed a novel proviral DNA-capture sequencing (proviral DNA-capture-seq) method investigating BLV proviral integration in two B-cell lymphoma lines, BLSC-KU1 and BLSC-KU17, derived from BLV-infected cattle with EBL. We designed BLV-specific biotinylated probes to capture the provirus genome and enrich libraries for next-generation sequencing. Validation showed high specificity and efficient enrichment of target sequence reads as well as identification of three BLV proviral integration sites on BLV persistently infected FLK-BLV cells as a positive control. We successfully detected a single BLV proviral integration site on chromosome 19 of BLSC-KU1 and chromosome 9 of BLSC-KU17, which were confirmed by standard PCR and Sanger sequencing. Further, a defective provirus in BLSC-KU1 and complete BLV proviral sequence in BLSC-KU17 were confirmed using long PCR and sequencing. This is the first study to provide comprehensive information on BLV proviral structure and viral integration in BLSC-KU1 and BLSC-KU17. Moreover, the proposed method can facilitate understanding of the detailed mechanisms underlying BLV-induced leukemogenesis and may be used as an innovative tool to screen BLV-infected cattle at risk at an earlier stage than those that have already developed lymphoma.

Proteomes of primary skin fibroblasts from healthy individuals reveal altered cell responses across the life span

Changes in the proteome of different human tissues with advancing age are poorly characterized. Here, we studied the proteins present in primary skin fibroblasts collected from 82 healthy individuals across a wide age spectrum (22-89 years old) who participated in the GESTALT (Genetic and Epigenetic Signatures of Translational Aging Laboratory Testing) study of the National Institute on Aging, NIH. Proteins were extracted from lysed fibroblasts and subjected to liquid chromatography-mass spectrometry analysis, and the expression levels of 9341 proteins were analyzed using linear regression models. We identified key pathways associated with skin fibroblast aging, including autophagy, scavenging of reactive oxygen species (ROS), ribosome biogenesis, DNA replication, and DNA repair. Changes in these prominent pathways were corroborated using molecular and cell culture approaches. Our study establishes a framework of the global proteome governing skin fibroblast aging and points to possible biomarkers and therapeutic targets.

The Interplay between Autophagy and Redox Signaling in Cardiovascular Diseases

Reactive oxygen and nitrogen species produced at low levels under normal cellular metabolism act as important signal molecules. However, at increased production, they cause damage associated with oxidative stress, which can lead to the development of many diseases, such as cardiovascular, metabolic, neurodegenerative, diabetes, and cancer. The defense systems used to maintain normal redox homeostasis plays an important role in cellular responses to oxidative stress. The key players here are Nrf2-regulated redox signaling and autophagy. A tight interface has been described between these two processes under stress conditions and their role in oxidative stress-induced diseases progression. In this review, we focus on the role of Nrf2 as a key player in redox regulation in cell response to oxidative stress. We also summarize the current knowledge about the autophagy regulation and the role of redox signaling in this process. In line with the focus of our review, we describe in more detail information about the interplay between Nrf2 and autophagy pathways in myocardium and the role of these processes in cardiovascular disease development.

The Mechanical Autophagy as a Part of Cellular Immunity; Facts and Features in Treating the Medical Disorders

Autophagy is a cellular housekeeping process that incorporates lysosomal-degradation to maintain cell survival and energy sources. In recent decades, the role of autophagy has implicated in the initiation and development of many diseases that affect humanity. Among these diseases are autoimmune diseases and neurodegenerative diseases, which connected with the lacking autophagy. Other diseases are connected with the increasing levels of autophagy such as cancers and infectious diseases. Therefore, controlling autophagy with sufficient regulators could represent an effective strategy to overcome such diseases. Interestingly, targeting autophagy can also provide a sufficient method to combat the current epidemic caused by the ongoing coronavirus. In this review, we aim to highlight the physiological function of the autophagic process to understand the circumstances surrounding its role in the cellular immunity associated with the development of human diseases.

ARF GTPases activate Salmonella effector SopF to ADP-ribosylate host V-ATPase and inhibit endomembrane damage-induced autophagy

Selective autophagy helps eukaryotes to cope with endogenous dangers or foreign invaders; its initiation often involves membrane damage. By studying a Salmonella effector SopF, we recently identified the vacuolar ATPase (V-ATPase)-ATG16L1 axis that initiates bacteria-induced autophagy. Here we show that SopF is an ADP-ribosyltransferase specifically modifying Gln124 of ATP6V0C in V-ATPase. We identify GTP-bound ADP-ribosylation factor (ARF) GTPases as a cofactor required for SopF functioning. Crystal structures of SopF-ARF1 complexes not only reveal structural basis of SopF ADP-ribosyltransferase activity but also a unique effector-binding mode adopted by ARF GTPases. Further, the N terminus of ARF1, although dispensable for high-affinity binding to SopF, is critical for activating SopF to modify ATP6V0C. Moreover, lysosome or Golgi damage-induced autophagic LC3 activation is inhibited by SopF or Q124A mutation of ATP6V0C, thus also mediated by the V-ATPase-ATG16L1 axis. In this process, the V-ATPase functions to sense membrane damages, which can be uncoupled from its proton-pumping activity.

Role of cardiolipins, mitochondria, and autophagy in the differentiation process activated by all-trans retinoic acid in acute promyelocytic leukemia

The role played by lipids in the process of granulocytic differentiation activated by all-trans retinoic acid (ATRA) in Acute-Promyelocytic-Leukemia (APL) blasts is unknown. The process of granulocytic differentiation activated by ATRA in APL blasts is recapitulated in the NB4 cell-line, which is characterized by expression of the pathogenic PML-RARα fusion protein. In the present study, we used the NB4 model to define the effects exerted by ATRA on lipid homeostasis. Using a high-throughput lipidomic approach, we demonstrate that exposure of the APL-derived NB4 cell-line to ATRA causes an early reduction in the amounts of cardiolipins, a major lipid component of the mitochondrial membranes. The decrease in the levels of cardiolipins results in a concomitant inhibition of mitochondrial activity. These ATRA-dependent effects are causally involved in the granulocytic maturation process. In fact, the ATRA-induced decrease of cardiolipins and the concomitant dysfunction of mitochondria precede the differentiation of retinoid-sensitive NB4 cells and the two phenomena are not observed in the retinoid-resistant NB4.306 counterparts. In addition, ethanolamine induced rescue of the mitochondrial dysfunction activated by cardiolipin deficiency inhibits ATRA-dependent granulocytic differentiation and induction of the associated autophagic process. The RNA-seq studies performed in parental NB4 cells and a NB4-derived cell population, characterized by silencing of the autophagy mediator, ATG5, provide insights into the mechanisms underlying the differentiating action of ATRA. The results indicate that ATRA causes a significant down-regulation of CRLS1 (Cardiolipin-synthase-1) and LPCAT1 (Lysophosphatidylcholine-Acyltransferase-1) mRNAs which code for two enzymes catalyzing the last steps of cardiolipin synthesis. ATRA-dependent down-regulation of CRLS1 and LPCAT1 mRNAs is functionally relevant, as it is accompanied by a significant decrease in the amounts of the corresponding proteins. Furthermore, the decrease in CRLS1 and LPCAT1 levels requires activation of the autophagic process, as down-regulation of the two proteins is blocked in ATG5-silenced NB4-shATG5 cells.

METTL3-mediated m6A modification of ATG7 regulates autophagy-GATA4 axis to promote cellular senescence and osteoarthritis progression

OBJECTIVE

The aim of the study was to investigate the role and regulatory mechanisms of fibroblast-like synoviocytes (FLSs) and their senescence in the progression of osteoarthritis (OA).

METHODS

Synovial tissues from normal patients and patients with OA were collected. Synovium FLS senescence was analysed by immunofluorescence and western blotting. The role of methyltransferase-like 3 (METTL3) in autophagy regulation was explored using N6-methyladenosine (m6A)-methylated RNA and RNA immunoprecipitation assays. Mice subjected to destabilisation of the medial meniscus (DMM) surgery were intra-articularly injected with or without pAAV9 loaded with small interfering RNA (siRNA) targeting METTL3. Histological analysis was performed to determine cartilage damage.

RESULTS

Senescent FLSs were markedly increased with the progression of OA in patients and mouse models. We determined that impaired autophagy occurred in OA-FLS, resulting in the upregulation of senescence-associated secretory phenotype (SASP). Re-establishment of autophagy reversed the senescent phenotype by suppressing GATA4. Further, we observed for the first time that excessive m6A modification negatively regulated autophagy in OA-FLS. Mechanistically, METTL3-mediated m6A modification decreased the expression of autophagy-related 7, an E-1 enzyme crucial for the formation of autophagosomes, by attenuating its RNA stability. Silencing METTL3 enhanced autophagic flux and inhibited SASP expression in OA-FLS. Intra-articular injection of synovium-targeted METTL3 siRNA suppressed cellular senescence propagation in joints and ameliorated DMM-induced cartilage destruction.

CONCLUSIONS

Our study revealed the important role of FLS senescence in OA progression. Targeted METTL3 inhibition could alleviate the senescence of FLS and limit OA development in experimental animal models, providing a potential strategy for OA therapy.

Ligustrazine protects against chronic hypertensive glaucoma in rats by inhibiting autophagy via the PI3K-Akt/mTOR pathway

PURPOSE

Glaucoma is a leading cause of global irreversible blindness, and characterized by the progressive loss of retinal ganglion cells (RGCs). Ligustrazine (TMP) is a natural product that has shown beneficial effects on various diseases. This study aimed to determine whether ligustrazine produces a therapeutic effect on glaucoma and to investigate its underlying mechanisms.

METHODS

A rat chronic hypertensive glaucoma model was induced by episcleral vein cauterization (EVC). Adult Sprague-Dawley (SD) rats were intraperitoneally administered TMP at a dose of 80 mg/kg once a day, from two days before EVC to one month after EVC. To elucidate the role of the mammalian target of rapamycin (mTOR) and phosphoinositide 3-kinase (PI3K), TMP-treated experimental rats were co-treated with the mTOR inhibitor rapamycin (5 mg/kg) or the PI3K inhibitor Ly294002 (10 mg/kg). The intraocular pressure (IOP) of the experimental and control rats was measured every six days. Retinal cells were examined by hematoxylin-eosin and terminal deoxynucleotidyltransferase-mediated biotinylated UTP nick end labeling (TUNEL) staining, as well as transmission electron microscopy. Immunohistochemistry and western blot analysis were performed to measure proteins involved in apoptosis and autophagy.

RESULTS

Ligustrazine protected retinal cells from death in experimental glaucoma rats, which was not due to the lowering of IOP, but could be attributable to direct suppression of retinal cell apoptosis. In glaucoma rats, autophagy was markedly activated in retina cells, as evidenced by increased numbers of autophagosomes and the expression of autophagy-related proteins (ATG5 and LC3-II/I). Notably, such alterations in glaucoma rats were almost completely reversed by ligustrazine. The suppressive effects of ligustrazine on apoptosis and autophagy of retina cells were markedly attenuated by the mTOR inhibitor rapamycin or the PI3K inhibitor Ly294002. Additionally, ligustrazine significantly increased the protein levels of phosphorylated PI3K (p-PI3K), protein kinase B (p-Akt), and mTOR (p-mTOR) in glaucoma rats, whereas such increases were attenuated by rapamycin or Ly294002.

CONCLUSIONS

These results demonstrate that ligustrazine is protective in experimental glaucoma by inhibiting autophagy via the activation of the PI3K-Akt/mTOR pathway, providing compelling evidence that ligustrazine is potentially therapeutic for patients with glaucoma.

Ivabradine protects rats against myocardial infarction through reinforcing autophagy via inhibiting PI3K/AKT/mTOR/p70S6K pathway

Ivabradine (Iva), a heart rate reducing agent that specifically inhibits the pacemaker I(f) ionic current, has been demonstrated to be cardioprotective in many cardiovascular diseases. Autophagy is an evolutionarily conserved metabolic process that regulates cardiac homeostasis. This study is aimed to explore whether autophagy is functionally involved in the cardioprotective effect of Iva in a rat model of myocardial infarction (MI). We observed that Iva treatment (po, 10 mg/kg/day) showed significant recovery on the hemodynamics parameters in MI rats, including left ventricular systolic pressure, left ventricular end diastolic pressure, and maximal ascending/descending rate of left ventricular pressure. Also, Iva treatment dramatically decreased infarct size, inhibited myocardial apoptosis, and reduced the levels of pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 in MI rats. Moreover, Iva treatment enhanced autophagy and inhibited PI3K/AKT/mTOR/p70S6K pathway in MI rats. Simultaneously, we observed that autophagy enhancer rapamycin (ip, 10 mg/kg/day) showed similar cardioprotective effects with Iva. Furthermore, we observed that addition of autophagy inhibitor 3-methyladenine (ip, 10 mg/kg/day) counteracted the therapeutic effect of Iva, addressing that Iva attenuated post-MI cardiac injury by enhancing autophagy. In summary, these findings demonstrated that Iva attenuated MI in rats by enhancing autophagy, and PI3K/AKT/mTOR/p70S6K pathway might be involved in the process. Autophagy activation by Iva may be a potential therapeutic strategy for the treatment of MI.