Autophagy

Inhibition of miR-146b-5p alleviates isoprenaline-induced cardiac hypertrophy via regulating DFCP1

Pathological cardiac hypertrophy often precedes heart failure due to various stimuli, yet effective clinical interventions remain limited. Recently, microRNAs (miRNAs) have been identified as critical regulators of cardiovascular development. In this study, we investigated the role of miR-146b-5p and its underlying mechanisms of action in cardiac hypertrophy. Isoprenaline (ISO) treatment induced significant hypertrophy and markedly enhanced the expression of miR-146b-5p in cultured neonatal rat cardiomyocytes and hearts of C57BL/6 mice. Transfection with the miR-146b-5p mimic led to cardiomyocyte hypertrophy accompanied by autophagy inhibition. Conversely, miR-146b-5p inhibition significantly alleviated ISO-induced autophagy depression, thereby mitigating cardiac hypertrophy both in vitro and in vivo. Our results showed that the autophagy-related mediator double FYVE domain-containing protein 1 (DFCP1) is a target of miR-146b-5p. MiR-146b-5p blocked autophagic flux in cardiomyocytes by suppressing DFCP1, thus contributing to hypertrophy. These findings revealed that miR-146b-5p is a potential regulator of autophagy associated with the onset of cardiac hypertrophy, suggesting a possible therapeutic strategy involving the inhibition of miR-146b-5p.

Resveratrol activates autophagy and protects from UVA-induced photoaging in human skin fibroblasts and the skin of male mice by regulating the AMPK pathway

Skin photoaging is mostly caused by ultraviolet A (UVA), although active medications to effectively counteract UVA-induced photoaging have not yet been created. Resveratrol, a naturally occurring polyphenol found in the skin of grapes, has been shown to have various biological functions such as anti-inflammatory and antioxidant characteristics. However, the role of resveratrol in UVA-induced photoaging has not been clarified. We investigated the mechanism of action of resveratrol by UVA irradiation of human skin fibroblasts (HSF) and innovatively modified a mouse model of photoaging. The results demonstrated that resveratrol promoted AMP-activated protein kinase (AMPK) phosphorylation to activate autophagy, reduce reactive oxygen species (ROS) production, inhibit apoptosis, and restore normal cell cycle to alleviate UVA-induced photoaging. In addition, subcutaneous injection of resveratrol not only improved the symptoms of roughness, erythema, and increased wrinkles in the skin of UVA photodamaged mice, but also alleviated epidermal hyperkeratosis and hyperpigmentation, reduced inflammatory responses, and inhibited collagen fiber degradation. In conclusion, our studies proved that resveratrol can treat UVA-induced photoaging and elucidated the possible molecular mechanisms involved, providing a new therapeutic strategy for future anti-aging.

Reasons why life on Earth rarely makes fluorine-containing compounds and their implications for the search for life beyond Earth

Life on Earth is known to rarely make fluorinated carbon compounds, as compared to other halocarbons. We quantify this rarity, based on our exhaustive natural products database curated from available literature. We build on explanations for the scarcity of fluorine chemistry in life on Earth, namely that the exclusion of the C-F bond stems from the unique physico-chemical properties of fluorine, predominantly its extreme electronegativity and strong hydration shell. We further show that the C-F bond is very hard to synthesize and when it is made by life its potential biological functions can be readily provided by alternative functional groups that are much less costly to incorporate into existing biochemistry. As a result, the overall evolutionary cost-to-benefit balance of incorporation of the C-F bond into the chemical repertoire of life is not favorable. We argue that the limitations of organofluorine chemistry are likely universal in that they do not exclusively apply to specifics of Earth's biochemistry. C-F bonds, therefore, will be rare in life beyond Earth no matter its chemical makeup.

Cardiovascular outcomes and molecular targets for the cardiac effects of Sodium-Glucose Cotransporter 2 Inhibitors: A systematic review

Sodium-glucose cotransporter 2 inhibitors (SGLT2i), a new class of glucose-lowering drugs traditionally used to control blood glucose levels in patients with type 2 diabetes mellitus, have been proven to reduce major adverse cardiovascular events, including cardiovascular death, in patients with heart failure irrespective of ejection fraction and independently of the hypoglycemic effect. Because of their favorable effects on the kidney and cardiovascular outcomes, their use has been expanded in all patients with any combination of diabetes mellitus type 2, chronic kidney disease and heart failure. Although mechanisms explaining the effects of these drugs on the cardiovascular system are not well understood, their effectiveness in all these conditions suggests that they act at the intersection of the metabolic, renal and cardiac axes, thus disrupting maladaptive vicious cycles while contrasting direct organ damage. In this systematic review we provide a state of the art of the randomized controlled trials investigating the effect of SGLT2i on cardiovascular outcomes in patients with chronic kidney disease and/or heart failure irrespective of ejection fraction and diabetes. We also discuss the molecular targets and signaling pathways potentially explaining the cardiac effects of these pharmacological agents, from a clinical and experimental perspective.

Neuronal Gtf2i deletion alters mitochondrial and autophagic properties

Gtf2i encodes the general transcription factor II-I (TFII-I), with peak expression during pre-natal and early post-natal brain development stages. Because these stages are critical for proper brain development, we studied at the single-cell level the consequences of Gtf2i's deletion from excitatory neurons, specifically on mitochondria. Here we show that Gtf2i's deletion resulted in abnormal morphology, disrupted mRNA related to mitochondrial fission and fusion, and altered autophagy/mitophagy protein expression. These changes align with elevated reactive oxygen species levels, illuminating Gtf2i's importance in neurons mitochondrial function. Similar mitochondrial issues were demonstrated by Gtf2i heterozygous model, mirroring the human condition in Williams syndrome (WS), and by hemizygous neuronal Gtf2i deletion model, indicating Gtf2i's dosage-sensitive role in mitochondrial regulation. Clinically relevant, we observed altered transcript levels related to mitochondria, hypoxia, and autophagy in frontal cortex tissue from WS individuals. Our study reveals mitochondrial and autophagy-related deficits shedding light on WS and other Gtf2i-related disorders.

Moringa oleifera and Autophagy: Evidence from In Vitro Studies on Chaperone-Mediated Autophagy in HepG2 Cancer Cells

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer in Sub-Saharan African countries, including South Africa (SA). Given the limitations in current HCC therapeutics, there is an increasing need for alternative adjuvant therapeutic options. As such, several cell survival mechanisms, such as autophagy, have been identified as potential adjuvant therapeutic targets in HCC treatment. Of the three most established autophagic pathways, the upregulation of chaperone-mediated autophagy (CMA) has been extensively described in various cancer cells, including HCC cells. CMA promotes tumor growth and chemotherapeutic drug resistance, thus contributing to HCC tumorigenesis. Therefore, the modulation of CMA serves as a promising adjuvant target for current HCC therapeutic strategies. Phytochemical extracts found in the medicinal plant, Moringa oleifera (MO), have been shown to induce apoptosis in numerous cancer cells, including HCC. MO leaves have the greatest abundance of phytochemicals displaying anticancer potential. However, the potential interaction between the pro-apoptotic effects of MO aqueous leaf extract and the survival-promoting role of CMA in an in vitro model of HCC remains unclear. This review aims to summarize the latest findings on the role of CMA, and MO in the progression of HCC.

Targeted protein degradation for the treatment of Parkinson's disease: Advances and future perspective

Parkinson's disease (PD) is a progressive disorder that belongs to a class of neurodegenerative disorders (NDs) called Synucleinopathies. It has characterized by the misfolding and aggregation of a-synuclein. Our understanding of PD continues to evolve, and so does our approach to treatment. including therapies aimed at delaying pathology, quitting neuronal loss, and shortening the course of the disease by selectively targeting essential proteins suspected to play a role in PD pathogenesis. One emerging approach that is generating significant interest is Targeted Protein Degradation (TPD). TPD is an innovative method that allows us to specifically break down certain proteins using specially designed molecules or peptides, like PROteolysis-TArgeting-Chimera (PROTACs). This approach holds great promise, particularly in the context of NDs. In this review, we will briefly explain PD and its pathogenesis, followed by discussing protein degradation systems and TPD strategy in PD by reviewing synthesized small molecules and peptides. Finally, future perspectives and challenges in the field are discussed.

Lipophagy: A potential therapeutic target for nonalcoholic and alcoholic fatty liver disease

Lipid droplets are unique lipid storage organelles in hepatocytes. Lipophagy is a key mechanism of selective degradation of lipid droplets through lysosomes. It plays a crucial role in the prevention of metabolic liver disease, including nonalcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (AFLD), and is a potential therapeutic target for treating these dysfunctions. In this review, we highlighted recent research and discussed advances in key proteins and molecular mechanisms related to lipophagy in liver disease. Reactive oxygen species (ROS) is an inevitable product of metabolism in alcohol-treated or high-fat-treated cells. Under this light, the potential role of ROS in autophagy in lipid droplet removal was initially explored to provide insights into the link between oxidative stress and metabolic liver disease. Subsequently, the current measures and drugs that treat NAFLD and AFLD through lipophagy regulation were summarized. The complexity of molecular mechanisms underlying lipophagy in hepatocytes and the need for further studies for their elucidation, as well as the status and limitations of current therapeutic measures and drugs, were also discussed.

Is TGR5 a therapeutic target for the treatment of spinal cord injury?

Bile acids, which are synthesized in liver and colon, facilitate the digestion of dietary lipids. In addition to this metabolic function, they also act as molecular signals with activities in the nervous system. These are mediated primarily by a G-protein-coupled bile acid receptor (known as TGR5). Preceded by a long tradition in Chinese medicine, bile acids are now being investigated as therapeutic options in several neuropathologies. Specifically, one bile acid, tauroursodeoxycholic acid (TUDCA), which passes the blood-brain barrier and shows anti-inflammatory and anti-apoptotic effects, has been tested in animal models of spinal cord injury (SCI). In this review, we discuss the evidence for a therapeutic benefit in these preclinical experiments. At the time of writing, 12 studies with TGR5 agonists have been published that report functional outcomes with rodent models of SCI. Most investigations found cytoprotective effects and benefits regarding the recovery of sensorimotor function in the subacute phase. When TUDCA was applied in a hydrogel into the lesion site, a significant improvement was obtained at 2 weeks after SCI. However, no lasting improvements with TUDCA treatment were found, when animals were assessed in later, chronic stages. A combination of TUDCA with stem cell injection failed to improve the effect of the cellular treatment. We conclude that the evidence does not support the use of TUDCA as a treatment of SCI. Nevertheless, cytoprotective effects suggest that different modes of application or combinatorial therapies might still be explored.

The interplay between oxidative stress and autophagy in chronic obstructive pulmonary disease

Autophagy is a highly conserved process that is indispensable for cell survival, embryonic development, and tissue homeostasis. Activation of autophagy protects cells against oxidative stress and is a major adaptive response to injury. When autophagy is dysregulated by factors such as smoking, environmental insults and aging, it can lead to enhanced formation of aggressors and production of reactive oxygen species (ROS), resulting in oxidative stress and oxidative damage to cells. ROS activates autophagy, which in turn promotes cell adaptation and reduces oxidative damage by degrading and circulating damaged macromolecules and dysfunctional cell organelles. The cellular response triggered by oxidative stress includes changes in signaling pathways that ultimately regulate autophagy. Chronic obstructive pulmonary disease (COPD) is the most common lung disease among the elderly worldwide, with a high mortality rate. As an induced response to oxidative stress, autophagy plays an important role in the pathogenesis of COPD. This review discusses the regulation of oxidative stress and autophagy in COPD, and aims to provide new avenues for future research on target-specific treatments for COPD.

The Therapeutic Relevance of Urolithins, Intestinal Metabolites of Ellagitannin-Rich Food: A Systematic Review of In Vivo Studies

The therapeutic effects of food rich in ellagitannins have been established to stem from its microbial metabolite, urolithin. Over the past decade, there has been a growing trend in urolithin research pertaining to its pharmacological properties. The purpose of this systematic review is to collate and synthesise all available data on urolithin’s therapeutic ability, to highlight its potential as a pharmaceutical agent, and prospective direction on future research. Methods: This systematic review was written based on the PRISMA guideline and was conducted across Ovid via Embase, Ovid MEDLINE, Cochrane Central Register for Controlled Trials, and Web of Science Core Collection. Results: A total of 41 animal studies were included in this systematic review based on the appropriate keyword. The included studies highlighted the neuroprotective, anti-metabolic disorder activity, nephroprotective, myocardial protective, anti-inflammatory, and musculoskeletal protection of urolithin A, B, and its synthetic analogue methylated urolithin A. The Sirt1, AMPK, and PI3K/AKT/mTOR signalling pathways were reported to be involved in the initiation of autophagy and mitochondrial biogenesis by urolithin A. Conclusions: This review methodically discusses the therapeutic prospects of urolithins and provides scientific justification for the potential development of urolithin A as a potent natural mitophagy inducer for anti-ageing purposes.

USP15 negatively regulates lung cancer progression through the TRAF6-BECN1 signaling axis for autophagy induction

TNF receptor-associated factor 6 (TRAF6)-BECN1 signaling axis plays a pivotal role in autophagy induction through ubiquitination of BECN1, thereby inducing lung cancer migration and invasion in response to toll-like receptor 4 (TLR4) stimulation. Herein, we provide novel molecular and cellular mechanisms involved in the negative effect of ubiquitin-specific peptidase 15 (USP15) on lung cancer progression. Clinical data of the TCGA and primary non-small cell lung cancer (NSCLC) patients (n = 41) revealed that the expression of USP15 was significantly downregulated in lung cancer patients. Importantly, USP15-knockout (USP15KO) A549 and USP15KO H1299 lung cancer cells generated with CRISPR-Cas9 gene-editing technology showed increases in cancer migration and invasion with enhanced autophagy induction in response to TLR4 stimulation. In addition, biochemical studies revealed that USP15 interacted with BECN1, but not with TRAF6, and induced deubiquitination of BECN1, thereby attenuating autophagy induction. Notably, in primary NSCLC patients (n = 4) with low expression of USP15, 10 genes (CCNE1, MMP9, SFN, UBE2C, CCR2, FAM83A, ETV4, MYO7A, MMP11, and GSDMB) known to promote lung cancer progression were significantly upregulated, whereas 10 tumor suppressor genes (FMO2, ZBTB16, FCN3, TCF21, SFTPA1B, HPGD, SOSTDC1, TMEM100, GDF10, and WIF1) were downregulated, providing clinical relevance of the functional role of USP15 in lung cancer progression. Taken together, our data demonstrate that USP15 can negatively regulate the TRAF6-BECN1 signaling axis for autophagy induction. Thus, USP15 is implicated in lung cancer progression.

Chemotherapy Resistance: Role of Mitochondrial and Autophagic Components

Simple Summary

Chemotherapy resistance is a common occurrence during cancer treatment that cancer researchers are attempting to understand and overcome. Mitochondria are a crucial intracellular signaling core that are becoming important determinants of numerous aspects of cancer genesis and progression, such as metabolic reprogramming, metastatic capability, and chemotherapeutic resistance. Mitophagy, or selective autophagy of mitochondria, can influence both the efficacy of tumor chemotherapy and the degree of drug resistance. Regardless of the fact that mitochondria are well-known for coordinating ATP synthesis from cellular respiration in cellular bioenergetics, little is known its mitophagy regulation in chemoresistance. Recent advancements in mitochondrial research, mitophagy regulatory mechanisms, and their implications for our understanding of chemotherapy resistance are discussed in this review.

Abstract

Cancer chemotherapy resistance is one of the most critical obstacles in cancer therapy. One of the well-known mechanisms of chemotherapy resistance is the change in the mitochondrial death pathways which occur when cells are under stressful situations, such as chemotherapy. Mitophagy, or mitochondrial selective autophagy, is critical for cell quality control because it can efficiently break down, remove, and recycle defective or damaged mitochondria. As cancer cells use mitophagy to rapidly sweep away damaged mitochondria in order to mediate their own drug resistance, it influences the efficacy of tumor chemotherapy as well as the degree of drug resistance. Yet despite the importance of mitochondria and mitophagy in chemotherapy resistance, little is known about the precise mechanisms involved. As a consequence, identifying potential therapeutic targets by analyzing the signal pathways that govern mitophagy has become a vital research goal. In this paper, we review recent advances in mitochondrial research, mitophagy control mechanisms, and their implications for our understanding of chemotherapy resistance.

Kidney protective potential of lactoferrin: pharmacological insights and therapeutic advances

Kidney disease is becoming a global public health issue. Acute kidney injury (AKI) and chronic kidney disease (CKD) have serious adverse health outcomes. However, there is no effective therapy to treat these diseases. Lactoferrin (LF), a multi-functional glycoprotein, is protective against various pathophysiological conditions in various disease models. LF shows protective effects against AKI and CKD. LF reduces markers related to inflammation, oxidative stress, apoptosis, and kidney fibrosis, and induces autophagy and mitochondrial biogenesis in the kidney. Although there are no clinical trials of LF to treat kidney disease, several clinical trials and studies on LF-based drug development are ongoing. In this review, we discussed the possible kidney protective mechanisms of LF, as well as the pharmacological and therapeutic advances. The evidence suggests that LF may become a potent pharmacological agent to treat kidney diseases.

Extraction of phenolic compounds from the shells of pecan nuts with cytotoxic activity through apoptosis against the colon cancer cell line HT-29

The water extraction of phenolic compounds from two varieties ("Mahan" and "Marameck") of pecan nutshells (Carya illinoinensis) without and with sonication, varying the solvent/solid ratio (S), the pH, and the refluxing time (t), was studied. Additionally, the in vitro cytotoxicity and the determination of the cell death mechanism of the extracts against the colon cancer cell line HT-29 were investigated. The content of total phenolic compounds (TPC) of "Marameck" nutshells resulted higher than for the "Mahan" variety, and the pH increase resulted in higher TPC contents for both cultivars. The optimized conditions for TPC extraction without and with sonication resulted: S = 33 ml/g, pH = 12, and t = 9.6 min, and yielded ≈ 70 and 90 mg/g of TPC for "Mahan" and "Marameck" nutshells, respectively. The optimized extracts of pecan nutshells without sonication from both cultivars presented similar cytotoxicity against HT-29 colon cancer cells (IC₅₀  ≈ 50 µg/ml), higher than for sonicated extracts (IC₅₀ ≈ 88 and 138 µg/ml for "Mahan" and "Marameck," respectively). Cell death through apoptosis was the main mechanism of cell death induced by the nutshell extracts. PRACTICAL APPLICATION: The extraction of phenolic compounds (TPC) from the residues of two varieties of pecan nutshells ("Mahan" and "Marameck") was studied. An optimal combination of variables within the pH range that minimizes the solvent-to-solid ratio (S) and the time of refluxing (t), saving at the same time, water and energy, was set up. The phenolic compound extracts obtained from the residues of the pecan nuts exhibit cytotoxic effects against colon cancer cells and could be of interest as an alternative treatment of different types of cancer. Additionally, these extracts may be of importance to the food industry as they can be used as antioxidant agents in food formulation. Also, the high levels of anthocyanidins obtained from the pecan nut extracts after proanthocyanidins' strong acid hydrolysis can be purified and employed as natural red dyes.

Betulinic acid in the treatment of tumour diseases: Application and research progress

Betulinic acid (BA) is a pentacyclic triterpene compound that can be obtained by separation, chemical synthesis and biotransformation from birch. BA has antitumour activity, and its mechanisms of action mainly include the induction of mitochondrial oxidative stress; the regulation of specificity protein transcription factors, and the inhibition of signal transducer and activator of transcription 3 and nuclear factor-κB signalling pathways. In addition, BA can increase the sensitivity of cancer cells to other chemotherapy drugs. Recent studies have shown that BA plays an anticancer role in several kinds of tumour diseases. In this article, the anticancer mechanism of BA and its application in the treatment of tumour diseases are reviewed.

Implications on the Therapeutic Potential of Statins via Modulation of Autophagy

Statins, which are functionally known as 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) inhibitors, are lipid-lowering compounds widely prescribed in patients with cardiovascular diseases (CVD). Several biological and therapeutic functions have been attributed to statins, including neuroprotection, antioxidation, anti-inflammation, and anticancer effects. Pharmacological characteristics of statins have been attributed to their involvement in the modulation of several cellular signaling pathways. Over the past few years, the therapeutic role of statins has partially been attributed to the induction of autophagy, which is critical in maintaining cellular homeostasis and accounts for the removal of unfavorable cells or specific organelles within cells. Dysregulated mechanisms of the autophagy pathway have been attributed to the etiopathogenesis of various disorders, including neurodegenerative disorders, malignancies, infections, and even aging. Autophagy functions as a double-edged sword during tumor metastasis. On the one hand, it plays a role in inhibiting metastasis through restricting necrosis of tumor cells, suppressing the infiltration of the inflammatory cell to the tumor niche, and generating the release of mediators that induce potent immune responses against tumor cells. On the other hand, autophagy has also been associated with promoting tumor metastasis. Several anticancer medications which are aimed at inducing autophagy in the tumor cells are related to statins. This review article discusses the implications of statins in the induction of autophagy and, hence, the treatment of various disorders.

Role and mechanisms of autophagy in lung metabolism and repair

Mammalian lungs are metabolically active organs that frequently encounter environmental insults. Stress responses elicit protective autophagy in epithelial barrier cells and the supportive niche. Autophagy promotes the recycling of damaged intracellular organelles, denatured proteins, and other biological macromolecules for reuse as components required for lung cell survival. Autophagy, usually induced by metabolic defects, regulates cellular metabolism. Autophagy is a major adaptive response that protects cells and organisms from injury. Endogenous region-specific stem/progenitor cell populations are found in lung tissue, which are responsible for epithelial repair after lung damage. Additionally, glucose and fatty acid metabolism is altered in lung stem/progenitor cells in response to injury-related lung fibrosis. Autophagy deregulation has been observed to be involved in the development and progression of other respiratory diseases. This review explores the role and mechanisms of autophagy in regulating lung metabolism and epithelial repair.

The effect of baicalein on endoplasmic reticulum stress and autophagy on liver damage

Carbon tetrachloride (CCl₄) is a toxic chemical that causes liver injury. CCl₄ triggers endoplasmic reticulum (ER) stress and unfolded protein response (UPR). UPR triggers autophagy to deal with the damage. The aim of this study was to investigate the effect of baicalein, derived from Scutellaria baicalensis, on CCl₄-induced liver damage concerning ER stress and autophagy. Two groups of Wistar albino rats (n = 7/groups) were treated with 0.2 ml/kg CCl₄ for 10 days with and without baicalein. Histological and transmission electron microscopy (TEM) analysis, autophagy, and ER stress markers measurements were carried out to evaluate the effect of baicalein. Histological examinations showed that baicalein reduced liver damage. TEM analysis indicated that baicalein inhibited ER stress and triggered autophagy. CCl4-induced elevation of C/EBP homologous protein (CHOP), glucose-regulating protein 78 (GRP78), activating transcription factor 4 (ATF4), activating transcription factor 6 (ATF6), inositol requiring enzyme 1 (IRE1), pancreatic ER kinase (PERK), and active/spliced form of X-box-binding protein 1 (XBP1s) ER stress markers were decreased by baicalein. Baicalein also increased the autophagy-related 5 (ATG5), Beclin1, and Microtubule-associated protein 1A/1B-light chain 3-phosphatidylethanolamine-conjugated form (LC3-II) autophagy marker levels. In conclusion, baicalein reduced the CCl₄-induced liver damage by inhibiting ER stress and the trigger of autophagy.

The role of extracellular vesicles in podocyte autophagy in kidney disease

Podocytes are the key cells involved in protein filtration in the glomerulus. Once proteins appear in the urine when podocytes fail, patients will end with renal failure due to the progression of glomerular damage if no proper treatment is applied. The injury and loss of podocytes can be attributed to diverse factors, such as genetic, immunologic, toxic, or metabolic disorders. Recently, autophagy has emerged as a key mechanism to eliminate the unwanted cytoplasmic materials and to prolong the lifespan of podocytes by alleviating cell damage and stress. Typically, the fundamental function of extracellular vesicles (EVs) is to mediate the intercellular communication. Recent studies have suggested that, EVs, especially exosomes, play a certain role in information transfer by communicating proteins, mRNAs, and microRNAs with recipient cells. Under physiological and pathological conditions, EVs assist in the bioinformation interchange between kidneys and other organs. It is suggested that EVs are related to the pathogenesis of acute kidney injury and chronic kidney disease, including glomerular disease, diabetic nephropathy, renal fibrosis and end-stage renal disease. However, the role of EVs in podocyte autophagy remains unclear so far. Here, this study integrated the existing information about the relevancy, diagnostic value and therapeutic potential of EVs in a variety of podocytes-related diseases. The accumulating evidence highlighted that autophagy played a critical role in the homeostasis of podocytes in glomerular disease.

Basic fibroblast growth factor accelerates myelin debris clearance through activating autophagy to facilitate early peripheral nerve regeneration

The successful removal of damaged myelin sheaths during Wallerian degeneration (WD) is essential for ensuring structural remodelling and functional recovery following traumatic peripheral nerve injury (PNI). Recent studies have established that autophagy involves myelin phagocytosis and cellular homoeostasis, and its disorder impairs myelin clearance. Based on the role of basic fibroblast growth factor (bFGF) on exerting neuroprotection and angiogenesis during nerve tissue regeneration, we now explicitly focus on the issue about whether the therapeutic effect of bFGF on supporting nerve regeneration is closely related to accelerate the autophagic clearance of myelin debris during WD. Using sciatic nerve crushed model, we found that bFGF remarkedly improved axonal outgrowth and nerve reconstruction at the early phase of PNI (14 days after PNI). More importantly, we further observed that bFGF could enhance phagocytic capacity of Schwann cells (SCs) to engulf myelin debris. Additionally, this enhancing effect is accomplished by autophagy activation and the increase of autophagy flux by immunoblotting and immune‐histochemical analyses. Taken together, our data suggest that the action of bFGF on modulating early peripheral nerve regeneration is closely associated with myelin debris removal by SCs, which might result in SC‐mediated autophagy activation, highlighting its insight molecular mechanism as a neuroprotective agent for repairing PNI.

Autophagy and the Wnt signaling pathway: A focus on Wnt/β-catenin signaling

Cellular homeostasis and adaptation to various environmental conditions are importantly regulated by the sophisticated mechanism of autophagy and its crosstalk with Wnt signaling and other developmental pathways. Both autophagy and Wnt signaling are involved in embryogenesis and differentiation. Autophagy is responsible for degradation and recycling of cytosolic materials by directing them to lysosomes through the phagophore compartment. A dual feedback mechanism regulates the interface between autophagy and Wnt signaling pathways. During nutrient deprivation, β-catenin and Dishevelled (essential Wnt signaling proteins) are targeted for autophagic degradation by LC3. When Wnt signaling is activated, β-catenin acts as a corepressor of one of the autophagy proteins, p62. In contrast, another key Wnt signaling protein, GSK3β, negatively regulates the Wnt pathway and has been shown to induce autophagy by phosphorylation of the TSC complex. This article reviews the interplay between autophagy and Wnt signaling, describing how β-catenin functions as a key cellular integration point coordinating proliferation with autophagy, and it discusses the clinical importance of the crosstalk between these mechanisms.

Autophagy inhibition protects from alveolar barrier dysfunction in LPS-induced ALI mice by targeting alveolar epithelial cells

OBJECTIVE

The aim of this study was to investigate whether autophagy is enhanced in alveolar epithelial cells as well as its role in alveolar barrier function of in lipopolysaccharide (LPS)-induced ALI mice.

MATERIALS AND METHODS

Autophagy inhibitors, including 3-methyladenine (3-MA) and chloroquine (CLQ), and LPS were intraperitoneally administered to mice. Histological evaluation and confocal microscopy, Western blot, transmission electron microscopy, and ELISA were performed for analysis. First, the mouse model of ALI was established. Then, autophagy level changes in the mouse lung as well as the effects of autophagy inhibition on indirect ALI and alveolar epithelial barrier function induced by LPS were assessed. Finally, pro-inflammatory factors in BALF from ALI mice after autophagy inhibition by 3-MA or CLQ administration were detected.

RESULTS

The experimental animal model of LPS-induced ALI had the expected features. In addition, autophagy in alveolar epithelial cells in ALI mice was enhanced. Furthermore, autophagy in alveolar epithelial cells promoted alveolar epithelial barrier dysfunction in LPS-induced ALI. Finally, autophagy inhibition resulted in reduced LPS-induced lung tissue inflammation.

CONCLUSION

These findings suggest that autophagy inhibition protects from alveolar barrier dysfunction in LPS-induced ALI mice by targeting alveolar epithelial cells.

A Low Dose of Nanoparticulate Silver Induces Mitochondrial Dysfunction and Autophagy in Adult Rat Brain

Extensive incorporation of silver nanoparticles (AgNPs) into many medical and consumer products has raised concerns about biosafety. Since nanosilver accumulates persistently in the central nervous system, it is important to assess its neurotoxic impacts. We investigated a model of prolonged exposure of adult rats to a low environmentally relevant dose of AgNPs (0.2 mg/kg b.w.). Ultrastructural analysis revealed pathological alterations in mitochondria such as swelling and cristolysis. Besides, elongated forms of mitochondria were present. Level of adenosine triphosphate was not altered after exposure, although a partial drop of mitochondrial membrane potential was noted. Induction of autophagy with only early autophagic forms was observed in AgNP-exposed rat brains as evidenced by ultrastructural markers. Increased expression of two protein markers of autophagy, beclin 1 and microtubule-associated proteins 1A/1B light chain 3B (MAP LC3-II), was observed, indicating induction of autophagy. Expression of lysosome-related Rab 7 protein and cathepsin B did not change, suggesting inhibition of physiological flux of autophagy. Our results show that exposure to a low, environmentally relevant dose of AgNPs leads to induction of autophagy in adult rat brain in response to partial mitochondrial dysfunction and to simultaneous interfering with an autophagic pathway. The cell compensates for the defective autophagy mechanism via development of enhanced mitochondrial biodynamic.

(+)-Bornyl p-Coumarate Extracted from Stem of Piper betle Induced Apoptosis and Autophagy in Melanoma Cells

(+)-Bornyl p-coumarate is an active substance that is abundant in the Piper betle stem and has been shown to possess bioactivity against bacteria and a strong antioxidative effect. In the current study, we examined the actions of (+)-bornyl p-coumarate against A2058 and A375 melanoma cells. The inhibition effects of (+)-bornyl p-coumarate on these cell lines were assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay and the underlying mechanisms were identified by immunostaining, flow cytometry and western blotting of proteins associated with apoptosis and autophagy. Our results demonstrated that (+)-bornyl p-coumarate inhibited melanoma cell proliferation and caused loss of mitochondrial membrane potential, demonstrating treatment induced apoptosis. In addition, western blotting revealed that the process is mediated by caspase-dependent pathways, release of cytochrome C, activation of pro-apoptotic proteins (Bax, Bad and caspase-3/-9) and suppression of anti-apoptotic proteins (Bcl-2, Bcl-xl and Mcl-1). Also, the upregulated expressions of p-PERK, p-eIF2α, ATF4 and CCAAT/enhancer-binding protein (C/EBP)-homologous protein (CHOP) after treatment indicated that (+)-bornyl p-coumarate caused apoptosis via endoplasmic reticulum (ER) stress. Moreover, increased expressions of beclin-1, Atg3, Atg5, p62, LC3-I and LC3-II proteins and suppression by autophagic inhibitor 3-methyladenine (3-MA), indicated that (+)-bornyl p-coumarate triggered autophagy in the melanoma cells. In conclusion, our findings demonstrated that (+)-bornyl p-coumarate suppressed human melanoma cell growth and should be further investigated with regards to its potential use as a chemotherapy drug for the treatment of human melanoma.

Naringenin Ameliorate Carbon Tetrachloride-Induced Hepatic Damage Through Inhibition of Endoplasmic Reticulum Stress and Autophagy in Rats

Hepatic fibrosis emerges upon exposure of liver to various chemicals and if not treated, it develops various diseases such as cirrhosis and cancer. Carbon tetrachloride (CCl₄) is a widely used toxin in animal models to develop hepatic fibrosis. Accumulation of unfolded proteins in cells causes stress in the endoplasmic reticulum (ER) and various mechanisms are involved in the cell to reduce the damage caused by these unfolding proteins. The most well known of these is the unfolded protein response. Further, autophagy works to remove these proteins if the damage cannot be repaired and is permanent. In our study, we investigated the effects of naringenin (NRG), a flavanon abundant in citrus fruits, on ER stress and autophagy in CCl₄-injured rat liver. The animals were given 0.2 mL/kg of CCl₄ for 10 days and treatment group was administered 100 mg/kg of NRG for 14 days. Histopathological examination was performed to show liver damage and to determine the therapeutic properties of the active substance. Transmission electron microscopy (TEM) analysis was carried out to establish cell level damage and effect of treatment. In addition, levels of ER stress and autophagy markers of liver were measured. According to our findings, TEM demonstrated positive effect of NRG and histological examinations reported ameliorative effects. In addition, NRG reduced levels of ER stress markers and inhibited autophagy significantly compared to CCl₄-treated group. As a result, NRG significantly reduced damage in hepatocytes and provided a significant amelioration.

ALS Genetics, Mechanisms, and Therapeutics: Where Are We Now?

The scientific landscape surrounding amyotrophic lateral sclerosis (ALS) continues to shift as the number of genes associated with the disease risk and pathogenesis, and the cellular processes involved, continues to grow. Despite decades of intense research and over 50 potentially causative or disease-modifying genes identified, etiology remains unexplained and treatment options remain limited for the majority of ALS patients. Various factors have contributed to the slow progress in understanding and developing therapeutics for this disease. Here, we review the genetic basis of ALS, highlighting factors that have contributed to the elusiveness of genetic heritability. The most commonly mutated ALS-linked genes are reviewed with an emphasis on disease-causing mechanisms. The cellular processes involved in ALS pathogenesis are discussed, with evidence implicating their involvement in ALS summarized. Past and present therapeutic strategies and the benefits and limitations of the model systems available to ALS researchers are discussed with future directions for research that may lead to effective treatment strategies outlined.

Loss of Rubicon ameliorates doxorubicin-induced cardiotoxicity through enhancement of mitochondrial quality

BACKGROUND

The therapeutic potential of doxorubicin (DOX) is limited by cardiotoxicity. Rubicon is an inhibitory interacting partner of autophagy protein UVRAG. Currently, the role of Rubicon in DOX-induced cardiotoxicity is unknown. In this study, we test the hypothesis that loss of Rubicon attenuates DOX-induced cardiotoxicity.

METHODS

A mouse model of acute DOX-induced cardiotoxicity was established by a single intraperitoneal injection of DOX at a dose of 20 mg/kg. Rubicon expression was detected by Western blot. Cardiac damage was determined by measuring activities of lactate dehydrogenase and myocardial muscle creatine kinase in the serum, cytoplasmic vacuolization, collagen deposition, ROS levels, ATP content and mitochondrial damage in the heart. Cardiac morphometry and function were assessed by echocardiography. Markers for autophagy, mitophagy and mitochondrial dynamics were evaluated by Western blot and real time reverse transcription polymerase chain reaction.

RESULTS

Rubicon expression was reduced in the heart 16 h after DOX treatment. DOX induced accumulation of cytoplasmic vacuolization and collagen, increased serum activities of lactate dehydrogenase and myocardial muscle creatine kinase, enhanced ROS levels, reduced ATP content, pronounced mitochondrial damage and greater left ventricular wall thickness in wild type mice, which were mitigated by Rubicon deficiency. Mechanistically, loss of Rubicon improved DOX-induced impairment of autophagic flux, Parkin-mediated mitophagy and mitochondrial fission and fusion in the heart.

CONCLUSIONS

Loss of Rubicon ameliorates DOX-induced cardiotoxicity through enhancement of mitochondrial quality by improving autophagic flux, mitophagy and mitochondrial dynamics. Rubicon is a potential molecular target for prevention and therapy of DOX cardiotoxicity.

RACK1 promotes tumorigenicity of colon cancer by inducing cell autophagy

RACK1 is upregulated in the various types of human cancers, and considered to play a role in the development and progression of human cancer. However, the role and mechanism of RACK in the colon cancer are poorly understood. In this study, we detected RACK1 expression in 63 normal colonic mucosa, 60 colonic inflammatory polyps, 60 colonic adenomas, 180 colon adenocarcinomas, and 40 lymph node metastases by immunohistochemistry, and observed that RACK1 expression was progressively elevated in the carcinogenic process of human colonic epithelium, and RACK1 expressional levels were positively correlated with the malignant degree and lymph node metastasis of colon cancers, and negatively correlated with the patient survival. With a combination of loss-of-function and gain-of-function approaches, we observed that RACK1 promoted colon cancer cell proliferation, inhibited colon cancer cell apoptosis, and enhanced the anchorage-independent and xenograft growth of colon cancer cells. Moreover, we found that RACK1-induced autophagy of colon cancer cells; RACK1-induced autophagy promoted colon cancer cell proliferation and inhibited colon cancer cell apoptosis. Our data suggest that RACK1 acts as an oncogene in colon cancer, and RACK1-induced autophagy promotes proliferation and survival of colon cancer, highlighting the therapeutic potential of autophagy inhibitor in the colon cancer with high RACK1 expression.

The Nedd8-activating enzyme inhibitor MLN4924 suppresses colon cancer cell growth via triggering autophagy

Neddylation is a post-translational protein modification process. MLN4924 is a newly discovered pharmaceutical neddylation inhibitor that suppresses cancer growth with several cancer types. In our study, we first investigated the effect of MLN4924 on colon cancer cells (HCT116 and HT29). MLN4924 significantly inhibited the neddylation of cullin-1 and colon cancer cell growth in a time and dose-dependent manner. MLN4924 induced G2/M cell cycle arrest and apoptosis in HCT116 and HT29 cells. Moreover, MLN4924 also triggered autophagy in HCT116 and HT29 cells via suppressing the PI3K/AKT/mTOR pathway. Inhibiting autophagy by autophagy inhibitor 3-MA or ATG5 knockdown reversed the function of MLN4924 in suppressing colon cancer cell growth and cell death. Interestingly, MLN4924 suppresses colon cell growth in a xenograft model. Together, our finding revealed that blocking neddylation is an attractive colon cancer therapy strategy, and autophagy might act as a novel anti-cancer mechanism for the treatment of colon cancer by MLN4924.

Mitophagy is activated in brain damage induced by cerebral ischemia and reperfusion via the PINK1/Parkin/p62 signalling pathway

This study examined the course of mitophagy following cerebral ischemia with reperfusion and the role of the PTEN-induced kinase 1 (PINK1)/Parkin/p62 signalling pathway. The middle cerebral artery of male Sprague-Dawley rats was occluded for 90 min and was followed by different time-points of reperfusion. Cerebral infarct areas were detected by 2,3,5-triphenyl tetrazolium chloride staining, while brain damage was observed by haematoxylin and eosin staining. Levels of LC3, Beclin1 and LAMP-1 were estimated by western blots. LC3B location was observed in various cells in the neurovascular unit. In addition, PINK1 accumulation in damaged mitochondria and Parkin/p62 mitochondrial translocation were investigated by double immunofluorescence staining. Finally, the levels of PINK1, Parkin and p62 expression in mitochondrial fractions were estimated by western blots. Cerebral ischemia with different time-points of reperfusion resulted in infarct in the territory of the middle cerebral artery accompanied by overall brain damage. In addition, we found up-regulation of LC3B, Beclin1, and LAMP-1, as well as mitophagy activation after reperfusion, with peak expression of these proteins at 24 h after reperfusion. Electron microscopy and immunofluorescence indicated that LC3B was primarily located in neurons, although lower levels of expression were found in astrocytes and even less in vascular endothelial cells. Moreover, significant increases in PINK1 accumulation in the outer membrane of mitochondria and increased Parkin/p62 mitochondrial translocation were shown at 24 h after reperfusion. These findings suggest that the PINK1/Parkin/p62 signalling pathway was involved in the pathophysiological processes following ischemia and reperfusion.

Ginsenoside Rg1 inhibits apoptosis by increasing autophagy via the AMPK/mTOR signaling in serum deprivation macrophages

Ginsenoside Rg1 (Rg1) has been widely used in a broad range of cardiovascular and cerebral-vascular diseases because of its unique therapeutic properties. However, the underlying mechanisms of Rg1 in the treatment of atherosclerosis have not been fully explored. This study sought to determine the precise molecular mechanisms on how Rg1 might be involved in regulating apoptosis in serum deprivation-induced Raw264.7 macrophages and primary bone marrow-derived macrophages. Results demonstrated that Rg1 treatment effectively suppressed apoptosis and the expression of phosphorylation level of mTOR induced by serum deprivation in Raw264.7 macrophages; the expressions of autophagic flux-related proteins including Atg5, Beclin1, microtubule-associated protein 1 light chain 3 (LC3), p62/SQSMT1, and the phosphorylation level of AMPK were concomitantly up-regulated. 3-Methyl-adennine (3-MA), the most widely used autophagy inhibitor, strongly up-regulated the expression of cleaved caspase-3, and blocked the anti-apoptosis function of Rg1 in macrophages. Importantly, autophagic flux was activated by Rg1, while Beclin1 knockdown partially abolished the anti-apoptosis of Rg1. Moreover, compound C, an AMPK inhibitor, partially decreased the expressions of phosphorylation of mTOR, Atg5, Beclin1, LC3, and p62/SQSMT1, which were increased by Rg1. AICAR, an AMPK inducer, promoted the protein expressions of phosphorylation of mTOR, Atg5, Beclin1, LC3, and p62/SQSMT1. In conclusion, Rg1 significantly suppressed apoptosis induced by serum deprivation in macrophages. Furthermore, Rg1 could effectively induce the autophagic flux by attenuating serum deprivation-induced apoptosis in Raw264.7 macrophages through activating the AMPK/mTOR signaling pathway.

Overaccumulation of p53-mediated autophagy protects against betulinic acid-induced apoptotic cell death in colorectal cancer cells

Betulinic acid (BA) exhibits cytotoxic activity against some cancer cells. However, the molecular mechanism of BA against CRC cells was little reported. Here, we proved that BA elicited CRC cells' growth inhibition and apoptosis in a dose-dependent manner. In addition, BA treatment induced autophagy via inhibiting the AKT-MTOR signaling pathway. Inhibition of autophagy by either administration of autophagic inhibitor chloroquine or siRNA-mediated knockdown of ATG5 could augment BA-induced apoptotic cell death as well as inhibition of cell proliferation. Moreover, we found that p53 was firstly activated by short exposure to BA and then was rapidly degraded via the ubiquitin-mediated degradation pathway in both wtp53 and mutp53 CRC cells. Notably, more preferential cytotoxicity of BA was obtained in mutp53 cells (IC50 values: HT29, 125 μM; SW480, 58 μM) rather than wtp53 cells (IC50 values: HCT116, 178 μM). Further experiments demonstrated that siRNA-mediated p53 knockdown attenuated BA-induced autophagy, and forced overexpression of p53 augmented BA-induced autophagy, indicating that p53-enhanced BA-induced autophagy. Moreover, BA enhanced the sensitivity of mutp53 cells to chemotherapy drugs such as 5-FU and ADR by degradation of mutp53. Overall, our study proved that BA could induce CRC cell death by inducing apoptosis and reduce the overaccumulation of BA-induced protective autophagy by degrading wtp53 and mutp53 dependent on the ubiquitin-mediated degradation pathway to achieve killer effect, suggesting that BA might serve as a novel desirable drug for mutp53 cancer therapy.

Isoliquiritigenin Induces Autophagy and Inhibits Ovarian Cancer Cell Growth

Ovarian cancer is one of the commonest gynecologic malignancies, which has a poor prognosis for patients at the advanced stage. Isoliquiritigenin (ISL), an active flavonoid component of the licorice plant, previously demonstrated antioxidant, anti-inflammatory, and tumor suppressive effects. In this study, we investigated the antitumor effect of ISL on human ovarian cancer in vitro using the human ovarian cancer cell lines, OVCAR5 and ES-2, as model systems. Our results show that ISL significantly inhibited the viability of cancer cells in a concentration- and time-dependent manner. Flow cytometry analysis indicated that ISL induced G2/M phase arrest. Furthermore, the expression of cleaved PARP, cleaved caspase-3, Bax/Bcl-2 ratio, LC3B-II, and Beclin-1 levels were increased in western blot analysis. To clarify the role of autophagy and apoptosis in the effect of ISL, we used the autophagy inhibitor-3-methyladenine (3-MA) to attenuate the punctate fluorescence staining pattern of the p62/sequestosome 1 (SQSTM1, red fluorescence) and LC3 (green fluorescence) proteins after ISL treatment, and 3-MA inhibited the cytotoxicity of ISL. These findings provide new information about the link between ISL-induced autophagy and apoptosis and suggest that ISL is a candidate agent for the treatment of human ovarian cancer.

Autophagy compensates impaired energy metabolism in CLPXP-deficient Podospora anserina strains and extends healthspan

The degradation of nonfunctional mitochondrial proteins is of fundamental relevance for maintenance of cellular homeostasis. The heteromeric CLPXP protein complex in the mitochondrial matrix is part of this process. In the fungal aging model Podospora anserina, ablation of CLPXP leads to an increase in healthy lifespan. Here, we report that this counterintuitive increase depends on a functional autophagy machinery. In PaClpXP mutants, autophagy is involved in energy conservation and the compensation of impairments in respiration. Strikingly, despite the impact on mitochondrial function, it is not mitophagy but general autophagy that is constitutively induced and required for longevity. In contrast, in another long‐lived mutant ablated for the mitochondrial PaIAP protease, autophagy is neither induced nor required for lifespan extension. Our data provide novel mechanistic insights into the capacity of different forms of autophagy to compensate impairments of specific components of the complex mitochondrial quality control network and about the biological role of mitochondrial CLPXP in the control of cellular energy metabolism.

Molecular mechanisms underlying metabolic syndrome: the expanding role of the adipocyte

The metabolic syndrome (MetS) is defined as a cluster of 3 or more metabolic and cardiovascular risk factors and represents a serious problem for public health. Altered function of adipose tissue has a significant impact on whole-body metabolism and represents a key driver for the development of these metabolic derangements, collectively referred as to MetS. In particular, increased visceral and ectopic fat deposition play a major role in the development of insulin resistance and MetS. A large body of evidence demonstrates that aging and MetS share several metabolic alterations. Of importance, molecular pathways that regulate lifespan affect key processes of adipose tissue physiology, and transgenic mouse models with adipose-specific alterations in these pathways show derangements of adipose tissue and other metabolic features of MetS, which highlights a causal link between dysfunctional adipose tissue and deleterious effects on whole-body homeostasis. This review analyzes adipose tissue-specific dysfunctions, including metabolic alterations that are related to aging, that have a significant impact on the development of MetS.-Armani, A., Berry, A., Cirulli, F., Caprio, M. Molecular mechanisms underlying metabolic syndrome: the expanding role of the adipocyte.

Mesenchymal Stromal Cells Deficient in Autophagy Proteins Are Susceptible to Oxidative Injury and Mitochondrial Dysfunction

Oxidative stress resulting from inflammatory responses that occur during acute lung injury and sepsis can initiate changes in mitochondrial function. Autophagy regulates cellular processes in the setting of acute lung injury, sepsis, and oxidative stress by modulating the immune response and facilitating turnover of damaged cellular components. We have shown that mesenchymal stromal cells (MSCs) improve survival in murine models of sepsis by also regulating the immune response. However, the effect of autophagy on MSCs and MSC mitochondrial function during oxidative stress is unknown. This study investigated the effect of depletion of autophagic protein microtubule-associated protein 1 light chain 3B (LC3B) and beclin 1 (BECN1) on the response of MSCs to oxidative stress. MSCs were isolated from wild-type (WT) and LC3B^-/- or Becn1^+/- mice. MSCs from the LC3B^-/- and Becn1^+/- animals had increased susceptibility to oxidative stress-induced cell death as compared with WT MSCs. The MSCs depleted of autophagic proteins also had impaired mitochondrial function (decreased intracellular ATP, reduced mitochondrial membrane potential, and increased mitochondrial reactive oxygen species production) under oxidative stress as compared with WT MSCs. In WT MSCs, carbon monoxide (CO) preconditioning enhanced autophagy and mitophagy, and rescued the cells from oxidative stress-induced death. CO preconditioning was not able to rescue the decreased survival of MSCs from the LC3B^-/- and Becn1^+/- animals, further supporting the tenet that CO exerts its cytoprotective effects via the autophagy pathway.

Adrenergic regulation of cytoplasmic structures related to secretory processes in pig pinealocytes-an ultrastructural, quantitative study

Two structures, considered as secretory in nature, are present in the pinealocytes in of the domestic pig show the presence of two structures, which are considered as secretory in nature - the dense core vesicles (DCV) and the membrane bounded (dense) bodies (MBB). The latter are extremely numerous in pig pinealocytes (they occupy 6-20% of the cytoplasm), and the number of MBB changes under different physiological and experimental conditions. Norepinephrine is the main neurotransmitter that regulates the secretion of pineal melatonin. The present study was carried out to 1) clarify whether the DCV and their source - the Golgi apparatus (GA) - as well as the MBB are controlled by norepinephrine, 2) determine the effect of adrenergic stimulation on these structures, and 3) identify the receptors involved in the regulation of these structures. The studies were performed using a static organ culture of pig pineal explants. The explants were incubated in a control medium between 08:00 and 20:00 and in a medium with 10μM norepinephrine or alpha- or beta-adrenoceptor agonists between 20:00 and 08:00 on five consecutive days. The tissues were subsequently prepared for ultrastructural analysis. The results distinctly showed that the DCV, GA and MBB in pig pinealocytes are under adrenergic control. The stimulation of the beta-adrenoceptors resulted in an increase in the numerical density of the DCV and a decrease in the relative volume of the GA in the perikarya, while the incubation with agonists of the alpha1-adrenoceptors was ineffective. The relative volume of the MBB in the perikarya significantly decreased after treatment with both beta-agonists and alpha1-agonists, which suggested the involvement of two types of adrenoceptors in the regulation of these structures.

Inhibition of autophagy by berberine enhances the survival of H9C2 myocytes following hypoxia

Hypoxia may induce apoptosis and autophagy to promote cardiomyocyte injury. The present study investigated the effect of berberine, a natural extract of Rhizoma Coptidis, on hypoxia‑induced autophagy and apoptosis in the H9c2 rat myocardial cell line. Expression levels of apoptosis and autophagy markers were upregulated in H9c2 myocytes during hypoxia and cell viability was reduced. However, berberine significantly reduced hypoxia‑induced autophagy in H9c2 myocytes, as demonstrated by the ratio of microtubule‑associated proteins 1A/1B light chain 3 I/II and the expression levels of B‑cell lymphoma 2 (Bcl‑2)/adenovirus E1B 19 kDa protein‑interacting protein 3, and promoted cell viability. In addition, expression levels of the Bcl‑2 anti‑apoptotic protein were significantly downregulated, and expression levels of pro‑apoptotic proteins Bcl‑2‑associated X protein and cleaved caspase‑3 were upregulated during hypoxia injury in cardiac myocytes. This was reversed by treatment with berberine or the autophagy inhibitor 3‑methyladenine, whereas the autophagy agonist rapamycin had the opposite effects, suggesting that berberine reduces myocyte cell death via inhibition of autophagy and apoptosis during hypoxia. In addition, Compound C, a 5' adenosine monophosphate‑activated protein kinase (AMPK) inhibitor, reduced apoptosis and autophagy in hypoxic myocytes, suggesting that the activation of the AMPK signaling pathway may be involved in this process. These findings suggested that berberine protects cells from hypoxia‑induced apoptosis via inhibition of autophagy and suppression of AMPK activation. Therefore, berberine may be a potential therapeutic agent for the treatment of patients with cardiac myocyte injury and ischemia.

Autophagy-related polymorphisms predict hypertension in patients with metastatic colorectal cancer treated with FOLFIRI and bevacizumab: Results from TRIBE and FIRE-3 trials

PURPOSE

The most frequent bevacizumab-related side-effects are hypertension, proteinuria, bleeding and thromboembolism. To date, there is no biomarker that predicts anti-VEGF-associated toxicity. As autophagy inhibits angiogenesis, we hypothesised that single-nucleotide polymorphisms (SNPs) within autophagy-related genes may predict bevacizumab-mediated toxicity in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Patients with mCRC treated with first-line FOLFIRI and bevacizumab in two phase III randomised trials, namely the TRIBE trial (n = 219, discovery cohort) and the FIRE-3 trial (n = 234, validation cohort) were included in this study. Patients receiving treatment with FOLFIRI and cetuximab (FIRE-3, n = 204) served as a negative control. 12 SNPs in eight autophagy-related genes (ATG3/5/8/13, beclin 1, FIP200, unc-51-like kinase 1, UVRAG) were analysed by PCR-based direct sequencing.

RESULTS

The FIP200 rs1129660 variant showed significant associations with hypertension in the TRIBE cohort. Patients harbouring any G allele of the FIP200 rs1129660 SNP showed a significantly lower rate of grade 2-3 hypertension compared with the A/A genotype (3% versus 15%, odds ratio [OR] 0.17; 95% confidence interval [CI], 0.02-0.73; P = 0.009). Similarly, G allele carriers of the FIP200 rs1129660 SNP were less likely to develop grade 2-3 hypertension than patients with an A/A genotype in the FIRE-3 validation cohort (9% versus 20%, OR 0.43; 95% CI, 0.14-1.11; P = 0.077), whereas this association could not be observed in the control cohort (12% versus 9%, OR 1.40; 95% CI, 0.45-4.04; P = 0.60).

CONCLUSION

This is the first report demonstrating that polymorphisms in the autophagy-related FIP200 gene may predict hypertension in patients with mCRC treated with FOLFIRI and bevacizumab.

Polyphyllin G induces apoptosis and autophagy cell death in human oral cancer cells

BACKGROUND

Polyphyllin G (also called polyphyllin VII), extract from rhizomes of Paris yunnanensis Franch, has been shown to have strong anticancer activities in a wide variety of human cancer cell lines. However, the underlying influences of autophagy in human oral squamous cell carcinoma (OSCC) remain unclear.

METHODS

In this study, the roles of apoptosis and autophagy in polyphyllin G-induced death in human oral cancer cells were investigated. Moreover, the molecular mechanism of the anticancer effects of polyphyllin G in human oral cancer cells was investigated.

RESULTS

The results revealed that polyphyllin G significantly inhibited cell proliferation in human oral cancer cells; it dose-dependently induced apoptosis in SAS and OECM-1 cells through caspase-3, -8, and -9 activation and poly (ADP-ribose) polymerase cleavage. In addition, changes were observed in Bcl-2 and proapoptosis-related protein expression in different human oral cancer cell lines. The expression of both LC3-II and beclin-1 was markedly increased, suggesting the induction of autophagy in polyphyllin G-treated oral cells. To further clarify whether polyphyllin G-induced apoptosis and autophagy depended on Akt/extracellular signal-regulated kinases (ERK)/c-Jun N-terminal kinases (JNK)/p38 mitogen-activated protein kinases (MAPK) signaling pathways, the cells were cotreated with inhibitors. The results demonstrated polyphyllin G-induced apoptosis in oral cells through the activation of ERK, Akt, p38 MAPK, and JNK, whereas ERK and JNK accounted for polyphyllin G-induced autophagy.

CONCLUSION

This study is the first to demonstrate apoptosis and autophagy during polyphyllin G-induced cell death in human oral cancer cell lines. These results suggest that polyphyllin G is a promising candidate for developing antitumor drugs targeting human oral squamous cell carcinoma.

14,15-Epoxyeicosatrienoic acid suppresses cigarette smoke condensate-induced inflammation in lung epithelial cells by inhibiting autophagy

Epoxyeicosatrienoic acids (EETs) are metabolic products of free arachidonic acid, which are produced through cytochrome P-450 (CYP) epoxygenases. EETs have anti-inflammatory, antiapoptotic, and antioxidative activities. However, the effect of EETs on cigarette smoke-induced lung inflammation is not clear. Autophagy is believed to be involved in the pathogenesis of chronic obstructive pulmonary disease. In addition, nuclear erythroid-related factor 2 (Nrf2), a transcription factor that regulates many antioxidant genes, is thought to regulate antioxidant defenses in several lung diseases. In addition, interaction between EETs, autophagy, and Nrf2 has been reported. The aim of this study was to explore the effect of 14,15-EET on cigarette smoke condensate (CSC)-induced inflammation in a human bronchial epithelial cell line (Beas-2B), and to determine whether the underlying mechanisms involved in the regulation of Nrf2 through inhibition of autophagy. Autophagy and expression of autophagy signaling pathway proteins (LC3B, p62, PI3K, Akt, p-Akt, and p-mTOR) and anti-inflammatory proteins (Nrf2 and HO-1) were assessed via Western blot analysis. Autophagosomes and autolysosomes were detected by adenoviral mRFP-GFP-LC3 transfection. Inflammatory factors (IL-6, IL-8, and MCP-1) were detected by ELISA. Lentiviral vectors carrying p62 short hairpin RNA were used to interfere with p62 expression to evaluate the effect of p62 on Nrf2 expression. Nrf2 expression was determined through immunocytochemistry. 14,15-EET treatment resulted in a significant reduction in IL-6, IL-8, and MCP-1 secretion, and increased accumulation of Nrf2 and expression of HO-1. In addition, 14,15-EET inhibited CSC-induced autophagy in Beas-2B cells. The mechanism of the anti-inflammatory effect of 14,15-EET involved inhibition of autophagy and an increase in p62 levels, followed by translocation of Nrf2 into the nucleus, which then upregulated expression of the antioxidant enzyme HO-1. 14,15-EET protects against CSC-induced lung inflammation by promoting accumulation of Nrf2 via inhibition of autophagy.

1-(2-Hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione Induces G1 Cell Cycle Arrest and Autophagy in HeLa Cervical Cancer Cells

The natural agent, 1-(2-hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione (HMDB), has been reported to have growth inhibitory effects on several human cancer cells. However, the role of HMDB in cervical cancer remains unclear. Herein, we found that HMDB dose- and time-dependently inhibited growth of HeLa cervical cancer cells, accompanied with G1 cell cycle arrest. HMDB decreased protein expression of cyclins D1/D3/E and cyclin-dependent kinases (CDKs) 2/4/6 and reciprocally increased mRNA and protein levels of CDK inhibitors (p15, p16, p21, and p27), thereby leading to the accumulation of hypophosphorylated retinoblastoma (Rb) protein. HMDB also triggered the accumulation of acidic vesicles and formation of microtubule-associated protein-light chain 3 (LC3), followed by increased expression of LC3 and Beclin-1 and decreased expression of p62, suggesting that HMDB triggered autophagy in HeLa cells. Meanwhile, suppression of the expression of survivin and Bcl-2 implied that HMDB-induced autophagy is tightly linked to apoptosis. Exploring the action mechanism, HMDB induced autophagy via the modulation of AMP-activated protein kinase (AMPK) and mTOR signaling pathway rather than the class III phosphatidylinositol 3-kinase pathway. These results suggest that HMDB inhibits HeLa cell growth by eliciting a G1 arrest through modulation of G1 cell cycle regulators and by concomitantly inducing autophagy through the mediation of AMPK-mTOR and Akt-mTOR pathways, and may be a promising antitumor agent against cervical cancer.

Glabridin induces apoptosis and autophagy through JNK1/2 pathway in human hepatoma cells

BACKGROUND

Extensive research results support the use of herbal medicine or natural food to augment therapy for various cancers. Studies have associated glabridin with numerous biological activities, such as regulating energy metabolism and estrogenic, neuroprotective, antiosteoporotic, and skin-whitening activities.

HYPOTHESIS/PURPOSE

However, how glabridin affects tumor cell autophagy has not been clearly determined.

METHODS

Autophagy is a lysosomal degradation pathway essential for cell survival and tissue homeostasis. In this study, the roles of autophagy and related signaling pathways during glabridin-induced autophagy in human liver cancer cells were investigated. Additionally, the molecular mechanism of the anticancer effects of glabridin in human hepatoma cells was investigated.

RESULTS

The results revealed that glabridin significantly inhibited cell proliferation in human hepatoma cells. Glabridin induced apoptosis dose-dependently in Huh7 cells through caspase-3, -8, and -9 activation and PARP cleavage. Furthermore, autophagy was detected as early as 12h after exposure to a low dose of glabridin, as indicated by the up-regulated expression of LC3-II and beclin-1 proteins. The inhibition of JNK1/2 and p38 MAPK by specific inhibitors significantly reduced glabridin-induced activation of caspases-3, -8, and -9. Blocking autophagy sensitize the Huh7 cells to apoptosis.

CONCLUSION

This study demonstrated for the first time that autophagy occurs earlier than apoptosis does during glabridin-induced apoptosis in human liver cancer cell lines. Glabridin induces Huh7 cell death through apoptosis through the p38 MAPK and JNK1/2 pathways and is a potential chemopreventive agent against human hepatoma.

Podocyte injury and repair mechanisms

PURPOSE OF REVIEW

Podocytes are the main gatekeeper of protein filtration in the glomerulus. When podocytes work less efficiently, this translates to the appearance of proteins in the urine, a condition that, if not promptly treated, leads to progression of glomerular damage and renal failure.

RECENT FINDINGS

Novel gene mutations have been uncovered in patients with nephrotic syndrome combined with a better definition of the role of podocin mutations. Although the importance of the inflammasome pathway and of the mechanisms of autophagy in podocyte health and disease have been increasingly recognized, a precise relationship between these processes still needs to be assessed. Numerous potential therapeutic targets have been identified and numerous data support the possibility of boosting podocyte regeneration. However, translation of experimental results into the clinic could largely depend on the avoidance of undesired side-effects; nanomedicine could provide the means to target old and novel drugs specifically to the podocytes.

SUMMARY

Podocytes are key cells in the glomerulus, and their damage inevitably leads to proteinuria and glomerular dysfunction. The more is known about the causes and mechanisms of podocyte damage, the more it will be possible to find new cures for glomerular diseases of the kidney.

Combined therapy with m-TOR-dependent and -independent autophagy inducers causes neurotoxicity in a mouse model of Machado-Joseph disease

A major pathological hallmark in several neurodegenerative disorders, like polyglutamine disorders (polyQ), including Machado-Joseph disease (MJD), is the formation of protein aggregates. MJD is caused by a CAG repeat expansion in the ATXN3 gene, resulting in an abnormal protein, which is prone to misfolding and forms cytoplasmic and nuclear aggregates within neurons, ultimately inducing neurodegeneration. Treatment of proteinopathies with drugs that up-regulate autophagy has shown promising results in models of polyQ diseases. Temsirolimus (CCI-779) inhibits the mammalian target of rapamycin (m-TOR), while lithium chloride (LiCl) acts by inhibiting inositol monophosphatase, both being able to induce autophagy. We have previously shown that chronic treatment with LiCl (10.4 mg/kg) had limited effects in a transgenic MJD mouse model. Also, others have shown that CCI-779 had mild positive effects in a different mouse model of the disease. It has been suggested that the combination of mTOR-dependent and -independent autophagy inducers could be a more effective therapeutic approach. To further explore this avenue toward therapy, we treated CMVMJD135 transgenic mice with a conjugation of CCI-779 and LiCl, both at concentrations known to induce autophagy and not to be toxic. Surprisingly, this combined treatment proved to be deleterious to both wild-type (wt) and transgenic animals, failing to rescue their neurological symptoms and actually exerting neurotoxic effects. These results highlight the possible dangers of manipulating autophagy in the nervous system and suggest that a better understanding of the potential disruption in the autophagy pathway in MJD is required before successful long-term autophagy modulating therapies can be developed.

Huaier Extract Induces Autophagic Cell Death by Inhibiting the mTOR/S6K Pathway in Breast Cancer Cells

Huaier extract is attracting increased attention due to its biological activities, including antitumor, anti-parasite and immunomodulatory effects. Here, we investigated the role of autophagy in Huaier-induced cytotoxicity in MDA-MB-231, MDA-MB-468 and MCF7 breast cancer cells. Huaier treatment inhibited cell viability in all three cell lines and induced various large membranous vacuoles in the cytoplasm. In addition, electron microscopy, MDC staining, accumulated expression of autophagy markers and flow cytometry revealed that Huaier extract triggered autophagy. Inhibition of autophagy attenuated Huaier-induced cell death. Furthermore, Huaier extract inhibited the mammalian target of the rapamycin (mTOR)/S6K pathway in breast cancer cells. After implanting MDA-MB-231 cells subcutaneously into the right flank of BALB/c nu/nu mice, Huaier extract induced autophagy and effectively inhibited xenograft tumor growth. This study is the first to show that Huaier-induced cytotoxicity is partially mediated through autophagic cell death in breast cancer cells through suppression of the mTOR/S6K pathway.