MTOR-independent autophagy induced by interrupted endoplasmic reticulum-mitochondrial Ca2+ communication: a dead end in cancer cells

The Wolfram-like variant WFS1E864K destabilizes MAM and compromises autophagy and mitophagy in human and mice

Dominant variants in WFS1 (wolframin ER transmembrane glycoprotein), the gene coding for a mitochondria-associated endoplasmic reticulum (ER) membrane (MAM) resident protein, have been associated with Wolfram-like syndrome (WLS). In vitro and in vivo, WFS1 loss results in reduced ER to mitochondria calcium (Ca2+) transfer, mitochondrial dysfunction, and enhanced macroautophagy/autophagy and mitophagy. However, in the WLS pathological context, whether the mutant protein triggers the same cellular processes is unknown. Here, we show that in human fibroblasts and murine neuronal cultures the WLS protein WFS1E864K leads to decreases in mitochondria bioenergetics and Ca2+ uptake, deregulation of the mitochondrial quality system mechanisms, and alteration of the autophagic flux. Moreover, in the Wfs1E864K mouse, these alterations are concomitant with a decrease of MAM number. These findings reveal pathophysiological similarities between WS and WLS, highlighting the importance of WFS1 for MAM's integrity and functionality. It may open new treatment perspectives for patients with WLS.Abbreviations: BafA1: bafilomycin A1; ER: endoplasmic reticulum; HSPA9/GRP75: heat shock protein family A (Hsp70) member 9; ITPR/IP3R: inositol 1,4,5-trisphosphate receptor; MAM: mitochondria-associated endoplasmic reticulum membrane; MCU: mitochondrial calcium uniporter; MFN2: mitofusin 2; OCR: oxygen consumption rate; ROS: reactive oxygen species; ROT/AA: rotenone+antimycin A; VDAC1: voltage dependent anion channel 1; WLS: Wolfram-like syndrome; WS: Wolfram syndrome; WT: wild-type.

Redox Regulation of Immunometabolism in Microglia Underpinning Diabetic Retinopathy

Diabetic retinopathy (DR) is the leading cause of visual impairment and blindness among the working-age population. Microglia, resident immune cells in the retina, are recognized as crucial drivers in the DR process. Microglia activation is a tightly regulated immunometabolic process. In the early stages of DR, the M1 phenotype commonly shifts from oxidative phosphorylation to aerobic glycolysis for energy production. Emerging evidence suggests that microglia in DR not only engage specific metabolic pathways but also rearrange their oxidation-reduction (redox) system. This redox adaptation supports metabolic reprogramming and offers potential therapeutic strategies using antioxidants. Here, we provide an overview of recent insights into the involvement of reactive oxygen species and the distinct roles played by key cellular antioxidant pathways, including the NADPH oxidase 2 system, which promotes glycolysis via enhanced glucose transporter 4 translocation to the cell membrane through the AKT/mTOR pathway, as well as the involvement of the thioredoxin and nuclear factor E2-related factor 2 antioxidant systems, which maintain microglia in an anti-inflammatory state. Therefore, we highlight the potential for targeting the modulation of microglial redox metabolism to offer new concepts for DR treatment.

PI3K signaling promotes formation of lipid-laden foamy macrophages at the spinal cord injury site

After spinal cord injury (SCI), infiltrating macrophages undergo excessive phagocytosis of myelin and cellular debris, forming lipid-laden foamy macrophages. To understand their role in the cellular pathology of SCI, investigation of the foamy macrophage phenotype in vitro revealed a pro-inflammatory profile, increased reactive oxygen species (ROS) production, and mitochondrial dysfunction. Bioinformatic analysis identified PI3K as a regulator of inflammation in foamy macrophages, and inhibition of this pathway decreased their lipid content, inflammatory cytokines, and ROS production. Macrophage-specific inhibition of PI3K using liposomes significantly decreased foamy macrophages at the injury site after a mid-thoracic contusive SCI in mice. RNA sequencing and in vitro analysis of foamy macrophages revealed increased autophagy and decreased phagocytosis after PI3K inhibition as potential mechanisms for reduced lipid accumulation. Together, our data suggest that the formation of pro-inflammatory foamy macrophages after SCI is due to the activation of PI3K signaling, which increases phagocytosis and decreases autophagy.

Perturbation of autophagy pathways in murine alveolar macrophage by 2D TMDCs is chalcogen-dependent

Increasing risks of incidental and occupational exposures to two-dimensional transition metal dichalcogenides (2D TMDCs) due to their broad application in various areas raised their public health concerns. While the composition-dependent cytotoxicity of 2D TMDCs has been well-recognized, how the outer chalcogenide atoms and inner transition metal atoms differentially contribute to their perturbation on cell homeostasis at non-lethal doses remains to be identified. In the present work, we compared the autophagy induction and related mechanisms in response to WS2, NbS2, WSe2 and NbSe2 nanosheets exposures in MH-S murine alveolar macrophages. All these 2D TMDCs had comparable physicochemical properties, overall cytotoxicity and capability in triggering autophagy in MH-S cells, but showed outer chalcogen-dependent subcellular localization and activation of autophagy pathways. Specifically, WS2 and NbS2 nanosheets adhered on the cell surface and internalized in the lysosomes, and triggered mTOR-dependent activation of autophagy. Meanwhile, WSe2 and NbSe2 nanosheets had extensive distribution in cytoplasm of MH-S cells and induced autophagy in an mTOR-independent manner. Furthermore, the 2D TMDCs-induced perturbation on autophagy aggravated the cytotoxicity of respirable benzo[a]pyrene. These findings provide a deeper insight into the potential health risk of environmental 2D TMDCs from the perspective of homeostasis perturbation.

Antitumor activity of miR-188-3p in gastric cancer is achieved by targeting CBL expression and inactivating the AKT/mTOR signaling

BACKGROUND

Altered miR-188-3p expression has been observed in various human cancers.

AIM

To investigate the miR-188-3p expression, its roles, and underlying molecular events in gastric cancer.

METHODS

Fifty gastric cancer and paired normal tissues were collected to analyze miR-188-3p and CBL expression. Normal and gastric cancer cells were used to manipulate miR-188-3p and CBL expression through different assays. The relationship between miR-188-3p and CBL was predicted bioinformatically and confirmed using a luciferase gene reporter assay. A Kaplan-Meier analysis was used to associate miR-188-3p or CBL expression with patient survival. A nude mouse tumor cell xenograft assay was used to confirm the in vitro data.

RESULTS

MiR-188-3p was found to be lower in the plasma of gastric cancer patients, tissues, and cell lines compared to their healthy counterparts. It was associated with overall survival of gastric cancer patients (P < 0.001), tumor differentiation (P < 0.001), lymph node metastasis (P = 0.033), tumor node metastasis stage (I/II vs III/IV, P = 0.024), and American Joint Committee on Cancer stage (I/II vs III/IV, P = 0.03). Transfection with miR-188-3p mimics reduced tumor cell growth and invasion while inducing apoptosis and autophagy. CBL was identified as a direct target of miR-188-3p, with its expression antagonizing the effects of miR-188-3p on gastric cancer (GC) cell proliferation by inducing tumor cell apoptosis and autophagy through the inactivation of the Akt/mTOR signaling pathway. The in vivo data confirmed antitumor activity via CBL downregulation in gastric cancer.

CONCLUSION

The current data provides ex vivo, in vitro, and in vivo evidence that miR-188-3p acts as a tumor suppressor gene or possesses antitumor activity in GC.

Importance of DJ-1 in autophagy regulation and disease

Autophagy is a highly conserved biological process that has evolved across evolution. It can be activated by various external stimuli including oxidative stress, amino acid starvation, infection, and hypoxia. Autophagy is the primary mechanism for preserving cellular homeostasis and is implicated in the regulation of metabolism, cell differentiation, tolerance to starvation conditions, and resistance to aging. As a multifunctional protein, DJ-1 is commonly expressed in vivo and is associated with a variety of biological processes. Its most widely studied role is its function as an oxidative stress sensor that inhibits the production of excessive reactive oxygen species (ROS) in the mitochondria and subsequently the cellular damage caused by oxidative stress. In recent years, many studies have identified DJ-1 as another important factor regulating autophagy; it regulates autophagy in various ways, most commonly by regulating the oxidative stress response. In particular, DJ-1-regulated autophagy is involved in cancer progression and plays a key role in alleviating neurodegenerative diseases(NDS) and defective reperfusion diseases. It could serve as a potential target for the regulation of autophagy and participate in disease treatment as a meaningful modality. Therefore, exploring DJ-1-regulated autophagy could provide new avenues for future disease treatment.

Key genes expressed in mitochondria‑endoplasmic reticulum contact sites in cancer (Review)

Cell fate is critically affected by mitochondrial activity, from ATP production to metabolism, Ca²⁺ homeostasis and signaling. These actions are regulated by proteins expressed in mitochondria (Mt)‑endoplasmic reticulum contact sites (MERCSs). The literature supports the fact that disruption to the physiology of the Mt and/or MERCSs can be due to alterations in the Ca²⁺ influx/efflux, which further regulates autophagy and apoptosis activity. The current review presents the findings of numerous studies with regard to the involvement of proteins positioned in MERCSs and how they express anti‑ and pro‑apoptotic properties by adjusting Ca²⁺ across membranes. The review also explores the involvement of mitochondrial proteins as hot spots in cancer development, cell death and/or survival, and the method via which they can potentially be targeted as a therapeutic option.

A Perspective on the Link between Mitochondria-Associated Membranes (MAMs) and Lipid Droplets Metabolism in Neurodegenerative Diseases

Mitochondria interact with the endoplasmic reticulum (ER) through contacts called mitochondria-associated membranes (MAMs), which control several processes, such as the ER stress response, mitochondrial and ER dynamics, inflammation, apoptosis, and autophagy. MAMs represent an important platform for transport of non-vesicular phospholipids and cholesterol. Therefore, this region is highly enriched in proteins involved in lipid metabolism, including the enzymes that catalyze esterification of cholesterol into cholesteryl esters (CE) and synthesis of triacylglycerols (TAG) from fatty acids (FAs), which are then stored in lipid droplets (LDs). LDs, through contact with other organelles, prevent the toxic consequences of accumulation of unesterified (free) lipids, including lipotoxicity and oxidative stress, and serve as lipid reservoirs that can be used under multiple metabolic and physiological conditions. The LDs break down by autophagy releases of stored lipids for energy production and synthesis of membrane components and other macromolecules. Pathological lipid deposition and autophagy disruption have both been reported to occur in several neurodegenerative diseases, supporting that lipid metabolism alterations are major players in neurodegeneration. In this review, we discuss the current understanding of MAMs structure and function, focusing on their roles in lipid metabolism and the importance of autophagy in LDs metabolism, as well as the changes that occur in neurogenerative diseases.

Synergistic mechanism between the endoplasmic reticulum and mitochondria and their crosstalk with other organelles

Organelles are functional areas where eukaryotic cells perform processes necessary for life. Each organelle performs specific functions; however, highly coordinated crosstalk occurs between them. Disorder of organelle networks often occur in various diseases. The endoplasmic reticulum (ER) and mitochondria are crucial organelles in eukaryotic cells as they are the material synthesis and oxidative metabolism centers, respectively. Homeostasis and orchestrated interactions are essential for maintaining the normal activities of cells. However, the mode and mechanism of organelle crosstalk is still a research challenge. Furthermore, the intricate association between organelle dyshomeostasis and the progression of many human diseases remains unclear. This paper systematically summarized the latest research advances in the synergistic mechanism between the endoplasmic reticulum and mitochondria and their crosstalk with other organelles based on recent literature. It also highlights the application potential of organelle homeostasis maintenance as a preventative and treatment strategy for diseases.

Tanshinone IIA Regulates MAPK/mTOR Signal-Mediated Autophagy to Alleviate Atherosclerosis through the miR-214-3p/ATG16L1 Axis

Tanshinone IIA (Tan IIA), the core ingredient of Salvia miltiorrhiza, is commonly used for treating cardiovascular diseases. However, its underlying mechanism in regulating autophagy in atherosclerosis (AS) remains unclear. An in vivo model of AS was constructed using Apolipoprotein E-deficient (ApoE-/-) mice fed with a high-fat diet. Histopathologic changes and lipid accumulation were evaluated by hematoxylin and eosin (HE) and Oil red O staining, respectively. The inflammatory cytokine levels were evaluated by Enzyme-linked immunosorbent assay (ELISA). An oxidized low-density lipoprotein (ox-LDL) was used to induce foam cells in RAW264.7 cells. Cholesterol uptake and efflux assay were used to assess changes in intracellular and extracellular cholesterol levels. The expression levels of autophagy-related protein-16-like protein 1 (ATG16L1) and miR-214-3p in the samples and cells derived from mice were assessed by quantitative real-time polymerase chain reaction (qRT-PCR), and the protein levels of the mitogen-activated protein kinase (MAPK)/mammalian target of rapamycin (mTOR) and autophagy-related markers were detected using western blot. The binding site of miR-214-3p on ATG16L1 was determined using a dual-luciferase reporter assay. We observed a decrease in ATG16L1 and increase in miR-214-3p expression level in the AS mice and ox-LDL stimulated RAW264.7 cells. However, the miR-214-3p and ATG16L1 expression could be reversed by Tan IIA. In vivo experiments showed that Tan IIA alleviated AS by reducing lipid accumulation and inflammatory factor levels and promoting autophagy. The in vitro assays demonstrated that Tan IIA regulated lipid levels and autophagy via the miR-214-3p/ATG16L1 axis to inhibit foam cell formation. Additionally, Tan IIA inhibited the MAPK/mTOR pathway by reducing miR-214-3p expression and promoting autophagy. Findings from this study suggested that Tan IIA regulated the MAPK/mTOR signal-mediated autophagy to alleviate AS through the miR-214-3p/ATG16L1 axis.

Hydrogen sulfide alleviates uremic cardiomyopathy by regulating PI3K/PKB/mTOR-mediated overactive autophagy in 5/6 nephrectomy mice

The gasotransmitter hydrogen sulfide (H₂S) plays important physiological and pathological roles in the cardiovascular system. However, the involvement of H₂S in recovery from uremic cardiomyopathy (UCM) remains unclear. This study aimed to determine the therapeutic efficacy and elucidate the underlying mechanisms of H₂S in UCM. A UCM model was established by 5/6 nephrectomy in 10-week-old C57BL/6 mice. Mice were treated with sodium hydrosulfide (NaHS, H₂S donor), L-cysteine [L-Cys, cystathionine gamma-lyase (CSE) substrate], and propargylglycine (PPG, CSE inhibitor). Treatment of H9C2 cardiomyocytes utilized different concentrations of uremic serum, NaHS, PPG, and PI3K inhibitors (LY294002). Mouse heart function was assessed by echocardiography. Pathological changes in mouse myocardial tissue were identified using hematoxylin and eosin and Masson's trichrome staining. Cell viability was assessed using the Cell Counting Kit-8. The protein expressions of CSE, p-PI3K, PI3K, p-PKB, PKB, p-mTOR, mTOR, and autophagy-related markers (Beclin-1, P62, and LC3) were detected using Western blotting. We found that NaHS and L-Cys treatment attenuated myocardial disarray, fibrosis, and left ventricular dysfunction in UCM mice. These abnormalities were further aggravated by PPG supplementation. Enhanced autophagy and decreased phosphorylation of PI3K, PKB, and mTOR protein expression by UCM were altered by NaHS and L-Cys treatment. In vitro, uremic serum increased overactive autophagy and decreased the phosphorylation levels of PI3K, PKB, and mTOR in cardiomyocytes, which was substantially exacerbated by endogenous H₂S deficiency and attenuated by pre-treatment with 100 µm NaHS. However, the protective effects of NaHS were completely inhibited by LY294002. These findings support a protective effect of H₂S exerted against UCM by reducing overactive autophagy through activation of the PI3K/PKB/mTOR pathway.

Mitochondria-Associated Endoplasmic Reticulum Membranes: Inextricably Linked with Autophagy Process

Mitochondria-associated membranes (MAMs), physical connection sites between the endoplasmic reticulum (ER) and the outer mitochondrial membrane (OMM), are involved in numerous cellular processes, such as calcium ion transport, lipid metabolism, autophagy, ER stress, mitochondria morphology, and apoptosis. Autophagy is a highly conserved intracellular process in which cellular contents are delivered by double-membrane vesicles, called autophagosomes, to the lysosomes for destruction and recycling. Autophagy, typically triggered by stress, eliminates damaged or redundant protein molecules and organelles to maintain regular cellular activity. Dysfunction of MAMs or autophagy is intimately associated with various diseases, including aging, cardiovascular, infections, cancer, multiple toxic agents, and some genetic disorders. Increasing evidence has shown that MAMs play a significant role in autophagy development and maturation. In our study, we concentrated on two opposing functions of MAMs in autophagy: facilitating the formation of autophagosomes and inhibiting autophagy. We recognized the link between MAMs and autophagy in the occurrence and progression of the diseases and therefore collated and summarized the existing intrinsic molecular mechanisms. Furthermore, we draw attention to several crucial data and open issues in the area that may be helpful for further study.

Balancing energy and protein homeostasis at ER-mitochondria contact sites

The endoplasmic reticulum (ER) is the largest organelle of the cell and participates in multiple essential functions, including the production of secretory proteins, lipid synthesis, and calcium storage. Sustaining proteostasis requires an intimate coupling with energy production. Mitochondrial respiration evolved to be functionally connected to ER physiology through a physical interface between both organelles known as mitochondria-associated membranes. This quasi-synaptic structure acts as a signaling hub that tunes the function of both organelles in a bidirectional manner and controls proteostasis, cell death pathways, and mitochondrial bioenergetics. Here, we discuss the main signaling mechanisms governing interorganellar communication and their putative role in diseases including cancer and neurodegeneration.

Cadmium induces apoptosis and autophagy in swine small intestine by downregulating the PI3K/Akt pathway

Cadmium (Cd) is an environmental contaminant, which is potentially toxic. It is well known that Cd can accumulate in the liver and kidney and cause serious damage. However, few studies have investigated the mechanism of intestinal damage induced by Cd in swine. Here, we established Cd poisoning models in vivo and in vitro to explore the mechanism of intestinal injury induced by Cd in swine. The morphology of intestinal tissue cells was observed by TUNEL staining and electron microscopy, and the morphology of IPEC-J2 cells was observed by flow cytometry, Hoechst staining, and MDC staining. Cell morphological observations revealed that Cd treatment induced ileal apoptosis and autophagy. The effects of Cd on the PI3K/Akt pathway, as well as on apoptosis and autophagy-related protein expression in intestinal cells, were analyzed by western blot (WB) and the expression of mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The results showed that Cd induced autophagy by increasing the levels of autophagy markers Beclin1, Autophagy-associated gene 5 (ATG5), Autophagy-associated gene 16 (ATG16), and Microtubule-associated protein light chains 3-2 (LC3-II), and by reducing the expression levels of Mechanistic target of rapamycin kinase (mTOR) and Microtubule-associated protein light chains 3-1 (LC3-I). Cell apoptosis was induced by increasing the expression of apoptosis markers Bcl-2 associated X protein (Bax), Cysteinyl aspartate specific proteinase 9 (Caspase9), cleaved Caspase9, Cysteinyl aspartate specific proteinase 3 (Caspase3), and cleaved Caspase3, and by reducing the expression of B cell lymphoma/leukemia 2 (Bcl-2). At the same time, Cd decreased the expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), and their phosphorylation. We treated IPEC-J2 cells with the PI3K activator 740Y-P and analyzed the morphological changes as well as autophagy and apoptosis-related gene expression. The results showed that 740Y-P could reduce apoptosis and autophagy induced by Cd. In conclusion, our findings suggest that Cd induces intestinal apoptosis and autophagy in swine by inactivating the PI3K/Akt signaling pathway.

Mitochondria-associated membranes: A hub for neurodegenerative diseases

In eukaryotic cells, organelles could coordinate complex mechanisms of signaling transduction metabolism and gene expression through their functional interactions. The functional domain between ER and mitochondria, called mitochondria-associated membranes (MAM), is closely associated with various physiological functions including intracellular lipid transport, Ca²⁺ transfer, mitochondria function maintenance, and autophagosome formation. In addition, more evidence suggests that MAM modulate cellular functions in health and disease. Studies have also demonstrated the association of MAM with numerous diseases, including neurodegenerative diseases, cancer, viral infection, obesity, and diabetes. In fact, recent evidence revealed a close relationship of MAM with Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), and other neurodegenerative diseases. In this view, elucidating the role of MAM in neurodegenerative diseases is particularly important. This review will focus the main tethering protein complexes of MAM and functions of MAM. Besides, the role of MAM in the regulation of neurodegenerative diseases and the potential molecular mechanisms is introduced to provide a new understanding of the pathogenesis of these diseases.

Repression of autophagy leads to acrosome biogenesis disruption caused by a sub-chronic oral administration of polystyrene nanoparticles

As a new widespread contaminant, nanoplastics (NPs) pose a potential risk to human health. Nevertheless, the adverse effects of NPs on the male reproductive system are poorly understood. In this study, we aimed to determine the effects of polystyrene nanoplastics (PS-NPs) (50 nm) on sperm quality, with a focus on the acrosome defects. After 35 days of intragastric administration, sperm quality was decreased and testicular structures were impaired in mice exposed to PS-NPs in both the medium (1.0 mg/kg) and high dose (10 mg/kg) groups. No significant changes were observed in the low dose (0.2 mg/kg) group. Meanwhile, acrosome parameters including acrosome integrity and acrosome reaction were decreased after the administration of PS-NPs. These findings were consistent with the disruption of acrosome biogenesis, as identified by the changed testicular ultrastructure. Additionally, the findings were further validated using seven marker genes (Gba2, Pick1, Gopc, Hrb, Zpbp1, Spaca1 and Dpy19l2) essential for acrosome formation, which showed that two of these genes (Gopc and Dpy19l2) were significantly down-regulated. Moreover, repressed autophagy was observed in the testes of PS-NPs-exposed mice based on autophagy-related protein expression. This phenomenon was further verified in GC-2spd cells treated with PS-NPs (50 μg/mL, 100 μg/mL, 200 μg/mL for 24 h). The potential role of autophagy in such acrosome defects was explored by using the autophagy inhibitor 3-methyladenine (3-MA), autophagy activator rapamycin or beclin-1 siRNA. The results showed that Golgi-associated vesicle disorganization was exacerbated with the 3-MA and beclin-1 siRNA pretreatments, but decreased with the rapamycin pretreatment, and the expression of GOPC and DPY19L2 was also altered. These results indicated that autophagy might be involved in the PS-NPs-induced acrosome lesions based on the regulation of two key acrosome-formation proteins, GOPC and DPY19L2. Altogether, our results will provide new insights into the PS-NPs-induced male reproductive impairment.

Mitochondrial Ca2+ Homeostasis: Emerging Roles and Clinical Significance in Cardiac Remodeling

Mitochondria are the sites of oxidative metabolism in eukaryotes where the metabolites of sugars, fats, and amino acids are oxidized to harvest energy. Notably, mitochondria store Ca²⁺ and work in synergy with organelles such as the endoplasmic reticulum and extracellular matrix to control the dynamic balance of Ca²⁺ concentration in cells. Mitochondria are the vital organelles in heart tissue. Mitochondrial Ca²⁺ homeostasis is particularly important for maintaining the physiological and pathological mechanisms of the heart. Mitochondrial Ca²⁺ homeostasis plays a key role in the regulation of cardiac energy metabolism, mechanisms of death, oxygen free radical production, and autophagy. The imbalance of mitochondrial Ca²⁺ balance is closely associated with cardiac remodeling. The mitochondrial Ca²⁺ uniporter (mtCU) protein complex is responsible for the uptake and release of mitochondrial Ca²⁺ and regulation of Ca²⁺ homeostasis in mitochondria and consequently, in cells. This review summarizes the mechanisms of mitochondrial Ca²⁺ homeostasis in physiological and pathological cardiac remodeling and the regulatory effects of the mitochondrial calcium regulatory complex on cardiac energy metabolism, cell death, and autophagy, and also provides the theoretical basis for mitochondrial Ca²⁺ as a novel target for the treatment of cardiovascular diseases.

YQFM alleviated cardiac hypertrophy by apoptosis inhibition and autophagy regulation via PI3K/AKT/mTOR pathway

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional compound preparation of Chinese medicine, Yiqi Fumai lyophilized injection (YQFM) has protective effects on various cardiac diseases including cardiac hypertrophy, which is the primary cause of arrhythmia. However, the involved mechanism remains unclear.

AIM OF THE STUDY

This study was projected to investigate whether YQFM could prevent cardiac hypertrophy and arrhythmia concurrence.

MATERIALS AND METHODS

The cardiac hypertrophy rats were established by transverse aortic ligation and the H9c2 hypertrophy cardiomyocyte was induced by angiotensin II (AngII). The electrocardiogram (ECG) was conducted to estimate the arrhythmia occurrence of cardiac hypertrophy rats under isoprenaline (iso) treatment. The cardiac related indicators and histopathology were also detected. The protective effects of YQFM on H9c2 hypertrophy cardiomyocyte were determined by the cell size measurement, apoptosis detection and mitochondrial membrane potential measurement. The cardiac hypertrophy relative proteins (ANP and BNP), autophagy related factors (LC3II, p62 and Beclin-1), apoptosis related markers (p53, caspase 3, Bax and Bcl-2) and the PI₃K/AKT/mTOR pathway expressions were all measured by Western blot.

RESULTS

YQFM decreased the arrhythmia occurrence and improved cardiac function in cardiac hypertrophy rats. YQFM also reduced the H9c2 cardiomyocyte size and alleviated the cardiomyocyte apoptosis induced by AngII. In addition, YQFM inhibited cell apoptosis by increasing Bcl-2/Bax ratio and decreasing caspase 3 and p53 expressions in vitro and vivo. Meanwhile, YQFM regulated the autophagy pathway by down-regulating of LC3II and Beclin-1 expressions, as well as up-regulating of p62 expression. Finally, the results showed that YQFM could activate the PI₃K/AKT/mTOR pathway by enhancing the p-AKT, p-PI₃K and p-mTOR expressions.

CONCLUSION

Our results displayed that YQFM attenuated the cardiac hypertrophy by apoptosis inhibition and autophagy regulation via PI₃K/AKT/mTOR pathway.

New focuses on roles of communications between endoplasmic reticulum and mitochondria in identification of biomarkers and targets

The communication between endoplasmic reticulum (ER) and mitochondria (Mt) plays important roles in maintenance of intra- and extra-cellular microenvironment, metabolisms, signaling activities and cell-cell communication. The present review aims to overview the advanced understanding about roles of ER-Mt structural contacts, molecular interactions and chemical exchanges, signal transmissions and inter-organelle regulations in ER-Mt communication. We address how the ER-Mt communication contributes to the regulation of lipid, amino acid and glucose metabolisms by enzymes, transporters and regulators in the process of biosynthesis. We specially emphasize the importance of deep understanding about molecular mechanisms of ER-Mt communication for identification and development of biology-specific, disease-specific and metabolism-specific biomarkers and therapeutic targets for human diseases. The inhibitors and modulators of the ER-Mt communication are categorized according to therapeutic targets. Rapid development of biotechnologies will provide new insights for spatiotemporally understanding the molecular mechanisms of ER-Mt communication.

Luteolin alleviates inorganic mercury-induced kidney injury via activation of the AMPK/mTOR autophagy pathway

Inorganic mercury is a ubiquitous toxic pollutant in the environment. Exposure to inorganic mercury can cause various poisonous effects, including kidney injury. However, no safe and effective treatment for kidney injury caused by inorganic mercury has been found and used. Luteolin (Lut) possesses various beneficial bioactivities. Here, our research aims to investigate the protective effect of Lut on renal injury induced by mercury chloride (HgCl₂) and identify the underlying autophagy regulation mechanism. Twenty-eight 6-8 weeks old Wistar rats were randomly assigned to four groups: control, HgCl₂, HgCl₂ + Lut, and Lut. We performed the determination of oxidative stress and renal function indicators, histopathological analysis, the terminal deoxynucleotidyl transferase-mediated deoxyuracil nucleoside triphosphate nick-end labeling assay to detect apoptosis, western blot detection of autophagy-related protein levels, and atomic absorption method to detect mercury content. Our results showed that Lut ameliorated oxidative stress, apoptosis and restored the autophagy and renal function caused by HgCl₂ in rats. Concretely, the level of nuclear factor E2-related factor, renal adenosine monophosphate-activated protein kinase (AMPK) expression, and autophagy regulation-related proteins levels were down-regulated, and the mammalian target of rapamycin (mTOR) expression was up-regulated by HgCl₂ treatment. However, Lut treatment reversed the above changes. Notably, Lut reduced the accumulation of HgCl₂ in the kidneys and promoted the excretion of HgCl₂ through urine. Collectively, our results demonstrate that Lut can attenuate inorganic mercury-induced renal injury via activating the AMPK/mTOR autophagy pathway. Therefore, Lut may be a potential biological medicine to protect against renal damage induced by HgCl₂.

Keeping zombies alive: The ER-mitochondria Ca2+ transfer in cellular senescence

Cellular senescence generates a permanent cell cycle arrest, characterized by apoptosis resistance and a pro-inflammatory senescence-associated secretory phenotype (SASP). Physiologically, senescent cells promote tissue remodeling during development and after injury. However, when accumulated over a certain threshold as happens during aging or after cellular stress, senescent cells contribute to the functional decline of tissues, participating in the generation of several diseases. Cellular senescence is accompanied by increased mitochondrial metabolism. How mitochondrial function is regulated and what role it plays in senescent cell homeostasis is poorly understood. Mitochondria are functionally and physically coupled to the endoplasmic reticulum (ER), the major calcium (Ca²⁺) storage organelle in mammalian cells, through special domains known as mitochondria-ER contacts (MERCs). In this domain, the release of Ca²⁺ from the ER is mainly regulated by inositol 1,4,5-trisphosphate receptors (IP3Rs), a family of three Ca²⁺ release channels activated by a ligand (IP3). IP3R-mediated Ca²⁺ release is transferred to mitochondria through the mitochondrial Ca²⁺ uniporter (MCU), where it modulates the activity of several enzymes and transporters impacting its bioenergetic and biosynthetic function. Here, we review the possible connection between ER to mitochondria Ca²⁺ transfer and senescence. Understanding the pathways that contribute to senescence is essential to reveal new therapeutic targets that allow either delaying senescent cell accumulation or reduce senescent cell burden to alleviate multiple diseases.

PEX5 prevents cardiomyocyte hypertrophy via suppressing the redox-sensitive signaling pathways MAPKs and STAT3

Peroxisomal biogenesis factor 5 (PEX5) is a member of peroxisome biogenesis protein family which serves as a shuttle receptor for the import of peroxisome matrix protein. The function of PEX5 on cardiomyocyte hypertrophy remained to be elucidated. Our study demonstrated that the protein expression level of PEX5 was declined in primary neonatal rat cardiomyocytes treated with phenylephrine (PE) and hearts from cardiac hypertrophic rats induced by abdominal aortic constriction (AAC). Overexpression of PEX5 alleviated cardiomyocyte hypertrophy induced by PE, while silencing of PEX5 exacerbated cardiomyocyte hypertrophy. PEX5 improved redox imbalance by decreasing cellular reactive oxygen species level and preserving peroxisomal catalase. Moreover, PEX5 knockdown aggravated PE-induced activation of redox-sensitive signaling pathways, including mitogen-activated protein kinase (MAPK) pathway and signal transducer and activator of transcription 3 (STAT3); whereas PEX5 overexpression suppressed activation of MAPK and STAT3. But PEX5 did not affect PE-induced phosphorylation of mammalian target of rapamycin (mTOR). In conclusion, the present study suggests that PEX5 protects cardiomyocyte against hypertrophy via regulating redox homeostasis and inhibiting redox-sensitive signaling pathways MAPK and STAT3.

Roles of Ion Fluxes, Metabolism, and Redox Balance in Cancer Therapy

Recent Advances: The 2019 Nobel Prize awarded to the mechanisms for oxygen sensing and adaptation according to oxygen availability, highlighting the fundamental importance of gaseous molecules. Gaseous molecules, including reactive oxygen species (ROS), can interact with different cations generated during metabolic and redox dysregulation in cancer cells. Cross talk between calcium signaling and metabolic/redox pathways leads to network-based dyregulation in cancer. Significance: Recent discovery on using small molecules targeting the ion channels, redox signaling, and protein modification on metabolic enzymes can effectively inhibit cancer growth. Several FDA-approved drugs and clinical trials are ongoing to target the calcium channels, such as TRPV6 and TRPM8. Multiple small molecules from natural products target metablic and redox enzymes to exert an anticancer effect. Critical Issues: Small molecules targeting key ion channels, metabolic enzymes that control key aspects of metabolism, and redox proteins are promising, but their action mechanisms of the target are needed to be elucidated with advanced-omic technologies, which can give network-based and highly dimensioal data. In addition, small molecules that can directly modify the protein residues have emerged as a novel anticancer strategy. Future Directions: Advanced technology accelerates the detection of ions and metabolic and redox changes in clinical samples for diagnosis and informs the decision of cancer treatment. The improvement of ROS detection, ROS target identification, and computational-aid drug discovery also improves clincal outcome.Overall, network-based or holistic regulations of cancer via ion therapy and metabolic and redox intervention are promising as new anticancer strategies. Antioxid. Redox Signal. 34, 1108-1127.

The ER-mitochondria Ca2+ signaling in cancer progression: Fueling the monster

Cancer is a leading cause of death worldwide. All major tumor suppressors and oncogenes are now recognized to have fundamental connections with metabolic pathways. A hallmark feature of cancer cells is a reprogramming of their metabolism even when nutrients are available. Increasing evidence indicates that most cancer cells rely on mitochondrial metabolism to sustain their energetic and biosynthetic demands. Mitochondria are functionally and physically coupled to the endoplasmic reticulum (ER), the major calcium (Ca²⁺) storage organelle in mammalian cells, through special domains known as mitochondria-ER contact sites (MERCS). In this domain, the release of Ca²⁺ from the ER is mainly regulated by inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs), a family of Ca²⁺ release channels activated by the ligand IP3. IP3R mediated Ca²⁺ release is transferred to mitochondria through the mitochondrial Ca²⁺ uniporter (MCU). Once in the mitochondrial matrix, Ca²⁺ activates several proteins that stimulate mitochondrial performance. The role of IP3R and MCU in cancer, as well as the other proteins that enable the Ca²⁺ communication between these two organelles is just beginning to be understood. Here, we describe the function of the main players of the ER mitochondrial Ca²⁺ communication and discuss how this particular signal may contribute to the rise and development of cancer traits.

Mechanism of the lifespan extension induced by submaximal SERCA inhibition in C. elegans

We have reported recently that submaximal inhibition of the Sarco Endoplasmic Reticulum Ca²⁺ ATPase (SERCA) produces an increase in the lifespan of C. elegans worms. We have explored here the mechanism of this increased survival by studying the effect of SERCA inhibition in several mutants of signaling pathways related to longevity. Our data show that the mechanism of the effect is unrelated with the insulin signaling pathway or the sirtuin activity, because SERCA inhibitors increased lifespan similarly in mutants of these pathways. However, the effect required functional mitochondria and both the AMP kinase and TOR pathways, as the SERCA inhibitors were ineffective in the corresponding mutants. The same effects were obtained after reducing SERCA expression with submaximal RNAi treatment. The SERCA inhibitors did not induce ER-stress at the concentrations used, and their effect was not modified by inactivation of the OP50 bacterial food. Altogether, our data suggest that the effect may be due to a reduced ER-mitochondria Ca²⁺ transfer acting via AMPK activation and mTOR inhibition to promote survival.

In the Right Place at the Right Time: Regulation of Cell Metabolism by IP3R-Mediated Inter-Organelle Ca2+ Fluxes

In the last few years, metabolism has been shown to be controlled by cross-organelle communication. The relationship between the endoplasmic reticulum and mitochondria/lysosomes is the most studied; here, inositol 1,4,5-triphosphate (IP3) receptor (IP3R)-mediated calcium (Ca²⁺) release plays a central role. Recent evidence suggests that IP3R isoforms participate in synthesis and degradation pathways. This minireview will summarize the current findings in this area, emphasizing the critical role of Ca²⁺ communication on organelle function as well as catabolism and anabolism, particularly in cancer.

The induction of AMPK-dependent autophagy leads to P53 degradation and affects cell growth and migration in kidney cancer cells

The most common subtype of renal cell carcinoma (RCC) is the clear cell RCC (ccRCC) that accounts for 70-80% of cases. The fate of ccRCC is linked to alterations of genes that regulate TP53. The dysfunction of p53 affects several processes including autophagy, which is increased in different advanced carcinomas and could be associated with cancer progression. We report that different kidney cancer cell lines show higher levels of autophagy than control cells. The increased autophagy is associated with the upregulation of miR501-5p, which stimulates mTOR-independent autophagy by the activation of AMP kinase. AMPK activation occurs through the decrease of ATP generation caused by the downregulation of the mitochondrial calcium uniporter (MCU) that leads to the reduction of mitochondrial calcium uptake. Autophagy induction promotes the degradation of p53 through the autophagolysosomal machinery. Consistently, the inhibition of autophagy reduces both cell proliferation and migration enhancing the expression of p53, p21 and E-Cadherin as well as decreasing Vimentin synthesis. Taken together, these findings indicate that autophagy is involved in the progression of kidney cancer. Therefore, the pharmacological targeting of this process could be considered an interesting option for the treatment of advanced renal carcinoma.

Maintaining social contacts: The physiological relevance of organelle interactions

Membrane-bound organelles in eukaryotic cells form an interactive network to coordinate and facilitate cellular functions. The formation of close contacts, termed "membrane contact sites" (MCSs), represents an intriguing strategy for organelle interaction and coordinated interplay. Emerging research is rapidly revealing new details of MCSs. They represent ubiquitous and diverse structures, which are important for many aspects of cell physiology and homeostasis. Here, we provide a comprehensive overview of the physiological relevance of organelle contacts. We focus on mitochondria, peroxisomes, the Golgi complex and the plasma membrane, and discuss the most recent findings on their interactions with other subcellular organelles and their multiple functions, including membrane contacts with the ER, lipid droplets and the endosomal/lysosomal compartment.

Mitochondria-Associated ER Membranes - The Origin Site of Autophagy

Autophagy is a process of intracellular self-recycling and degradation that plays an important role in maintaining cell homeostasis. However, the molecular mechanism of autophagy remains to be further studied. Mitochondria-associated endoplasmic reticulum membranes (MAMs) are the region of the ER that mediate communication between the ER and mitochondria. MAMs have been demonstrated to be involved in autophagy, Ca²⁺ transport and lipid metabolism. Here, we discuss the composition and function of MAMs, more specifically, to emphasize the role of MAMs in regulating autophagy. Finally, some key information that may be useful for future research is summarized.

Cancer cells with defective oxidative phosphorylation require endoplasmic reticulum-to-mitochondria Ca2+ transfer for survival

Spontaneous Ca²⁺ signaling from the InsP₃R intracellular Ca²⁺ release channel to mitochondria is essential for optimal oxidative phosphorylation (OXPHOS) and ATP production. In cells with defective OXPHOS, reductive carboxylation replaces oxidative metabolism to maintain amounts of reducing equivalents and metabolic precursors. To investigate the role of mitochondrial Ca²⁺ uptake in regulating bioenergetics in these cells, we used OXPHOS-competent and OXPHOS-defective cells. Inhibition of InsP₃R activity or mitochondrial Ca²⁺ uptake increased α-ketoglutarate (αKG) abundance and the NAD⁺/NADH ratio, indicating that constitutive endoplasmic reticulum (ER)-to-mitochondria Ca²⁺ transfer promoted optimal αKG dehydrogenase (αKGDH) activity. Reducing mitochondrial Ca²⁺ inhibited αKGDH activity and increased NAD⁺, which induced SIRT1-dependent autophagy in both OXPHOS-competent and OXPHOS-defective cells. Whereas autophagic flux in OXPHOS-competent cells promoted cell survival, it was impaired in OXPHOS-defective cells because of inhibition of autophagosome-lysosome fusion. Inhibition of αKGDH and impaired autophagic flux in OXPHOS-defective cells resulted in pronounced cell death in response to interruption of constitutive flux of Ca²⁺ from ER to mitochondria. These results demonstrate that mitochondria play a fundamental role in maintaining bioenergetic homeostasis of both OXPHOS-competent and OXPHOS-defective cells, with Ca²⁺ regulation of αKGDH activity playing a pivotal role. Inhibition of ER-to-mitochondria Ca²⁺ transfer may represent a general therapeutic strategy against cancer cells regardless of their OXPHOS status.

Enzyme-Instructed Assemblies Enable Mitochondria Localization of Histone H2B in Cancer Cells

Presently, little is known of how the inter-organelle crosstalk impacts cancer cells owing to the lack of approaches that can manipulate inter-organelle communication in cancer cells. We found that a negatively charged, enzyme cleavable peptide (MitoFlag) enables the trafficking of histone protein H2B, a nuclear protein, to the mitochondria in cancer cells. MitoFlag interacts with the nuclear location sequence of H2B to block it from entering the nucleus. A protease on the mitochondria cleaves the Flag from the MitoFlag/H2B complex to form assemblies that retain H2B on the mitochondria and facilitate H2B entering the mitochondria. Adding NLS, replacing aspartic acid by glutamic acid residues, or changing the l- to d-aspartic acid residue on MitoFlag abolishes the trafficking of H2B into mitochondria of HeLa cells. As the first example of the enzyme-instructed self-assembly of a synthetic peptide for trafficking endogenous proteins, this work provides insights for understanding and manipulating inter-organelle communication in cells.

PINK1 Activation and Translocation to Mitochondria-Associated Membranes Mediates Mitophagy and Protects Against Hepatic Ischemia/Reperfusion Injury

Hepatic ischemia/reperfusion (I/R) injury is a major concern in liver surgery settings. Mitochondria are critical targets or the origin of tissue injury, particularly I/R injury. Mitophagy, a selective form of autophagy, is a fundamental process that removes damaged or unwanted mitochondria for mitochondrial quality control, but its role in hepatic I/R remains unclear. In the present study, we investigated the role of mitophagy in hepatic I/R by focusing on PTEN-induced putative kinase 1 (PINK1). Livers from 10-week-old mice and primary hepatocytes were subjected to in vivo hepatic I/R and in vitro hypoxia-reoxygenation (H/R), respectively. Analyses of oxidative stress, immunoblotting, and ATP generation showed that hepatic I/R leads to mitochondrial damage. Dysfunctional mitochondria promoted reactive oxygen species (ROS) production and apoptosis. Hepatic I/R led to decreases in the mitochondrial proteins COX4 and TOM20 and mitochondrial DNA and increases in the autophagy-related indicators LC3 and P62, which indicates that hepatic I/R promotes mitophagy. We found that I/R also leads to endoplasmic reticulum stress, which has frequent signal communication with mitochondria through the mitochondria-associated membranes (MAMs). We showed that the mitophagy-related proteins Parkin, Beclin, optineurin were enhanced in hepatic I/R. No significant change is in PINK1 but it translocated to MAMs region to initiate mitophagy. The silencing PINK1 by shRNA in cultured primary hepatocytes reduced the level of H/R-induced mitophagy, leading to the accumulation of dysfunctional mitochondria during H/R, increased production of ROS, mitochondria-induced apoptosis, and eventually hepatocyte death. Taken together, these findings indicate that PINK1-mediated mitophagy plays a key role in mitochondrial quality control and liver cell survival during I/R.

Hypomethylation-Linked Activation of PLCE1 Impedes Autophagy and Promotes Tumorigenesis through MDM2-Mediated Ubiquitination and Destabilization of p53

Esophageal squamous cell carcinoma (ESCC) is one of the deadliest malignant diseases. Multiple studies with large clinic-based cohorts have revealed that variations of phospholipase C epsilon 1 (PLCE1) correlate with esophageal cancer susceptibility. However, the causative role of PLCE1 in ESCC has remained elusive. Here, we observed that hypomethylation-mediated upregulation of PLCE1 expression was implicated in esophageal carcinogenesis and poor prognosis in ESCC cohorts. PLCE1 inhibited cell autophagy and suppressed the protein expression of p53 and various p53-targeted genes in ESCC. Moreover, PLCE1 decreased the half-life of p53 and promoted p53 ubiquitination, whereas it increased the half-life of mouse double minute 2 homolog (MDM2) and inhibited its ubiquitination, leading to MDM2 stabilization. Mechanistically, the function of PLCE1 correlated with its direct binding to both p53 and MDM2, which promoted MDM2-dependent ubiquitination of p53 and subsequent degradation in vitro. Consequently, knockdown of PLCE1 combined with transfection of a recombinant adenoviral vector encoding wild-type p53 resulted in significantly increased levels of autophagy and apoptosis of esophageal cancer in vivo. Clinically, the upregulation of PLCE1 and mutant p53 protein predicted poor overall survival of patients with ESCC, and PLCE1 was positively correlated with p53 in ESCC cohorts. Collectively, this work identified an essential role for PLCE1- and MDM2-mediated ubiquitination and degradation of p53 in inhibiting ESCC autophagy and indicates that targeting the PLCE1-MDM2-p53 axis may provide a novel therapeutic approach for ESCC. SIGNIFICANCE: These findings identify hypomethylation-mediated activation of PLCE1 as a potential oncogene that blocks cellular autophagy of esophageal carcinoma by facilitating the MDM2-dependent ubiquitination of p53 and subsequent degradation. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/11/2175/F1.large.jpg.

HO-1 induced autophagy protects against IL-1 β-mediated apoptosis in human nucleus pulposus cells by inhibiting NF-κB

In this study, we investigated the role of heme oxygenase-1 (HO-1) in intervertebral disc degeneration (IDD) by assessing the effects of HO-1 overexpression on IL-1β-induced apoptosis in nucleus pulposus cells (NPCs). Immunohistochemical staining showed HO-1 expression to be lower in NPCs from IDD patients than from patients with lumbar vertebral fractures (LVF). Western blot analysis showed HO-1 and LC3-II/I levels to be lower in NP tissues from IDD patients than from LVF patients, suggesting suppression of autophagy in degenerative intervertebral disc. Consistent with that idea, autophagy was increased in HO-1-overexpressing NPCs while IL-1β-induced apoptosis was reduced. These effects were reversed by treatment with the early autophagy inhibitor 3-methyl adenine, which suggests HO-1-induced autophagy suppresses IL-1β-induced apoptosis in NPCs. HO-1 overexpression promoted autophagy by increasing levels of Beclin-1/PI3KC3 complex. Phospho-P65 levels were lower in HO-1-overexpressing NPCs, suggesting inhibition of NF-κB-mediated apoptosis. Our study thus demonstrates that HO-1 promotes autophagy by enhancing formation of Beclin-1/PI3KC3 complex and suppresses IL-1β-induced apoptosis by inhibiting NF-κB. We suggest that HO-1 is a potential therapeutic target to alleviate IDD.

Autophagy in kidney disease: Advances and therapeutic potential

Autophagy is a highly conserved intracellular catabolic process for the degradation of cytoplasmic components that has recently gained increasing attention for its importance in kidney diseases. It is indispensable for the maintenance of kidney homeostasis both in physiological and pathological conditions. Investigations utilizing various kidney cell-specific conditional autophagy-related gene knockouts have facilitated the advancement in understanding of the role of autophagy in the kidney. Recent findings are raising the possibility that defective autophagy exerts a critical role in different pathological conditions of the kidney. An emerging body of evidence reveals that autophagy exhibits cytoprotective functions in both glomerular and tubular compartments of the kidney, suggesting the upregulation of autophagy as an attractive therapeutic strategy. However, there is also accumulating evidence that autophagy could be deleterious, which presents a formidable challenge in developing therapeutic strategies targeting autophagy. Here, we review the recent advances in research on the role of autophagy during different pathological conditions, including acute kidney injury (AKI), focusing on sepsis, ischemia-reperfusion injury, cisplatin, and heavy metal-induced AKI. We also discuss the role of autophagy in chronic kidney disease (CKD) focusing on the pathogenesis of tubulointerstitial fibrosis, podocytopathies including focal segmental glomerulosclerosis, diabetic nephropathy, IgA nephropathy, membranous nephropathy, HIV-associated nephropathy, and polycystic kidney disease.

Recent Insights into the Mitochondrial Role in Autophagy and Its Regulation by Oxidative Stress

Autophagy is a self-digestive process that degrades intracellular components, including damaged organelles, to maintain energy homeostasis and to cope with cellular stress. Autophagy plays a key role during development and adult tissue homeostasis, and growing evidence indicates that this catalytic process also has a direct role in modulating aging. Although autophagy is essentially protective, depending on the cellular context and stimuli, autophagy outcome can lead to either abnormal cell growth or cell death. The autophagic process requires a tight regulation, with cellular events following distinct stages and governed by a wide molecular machinery. Reactive oxygen species (ROS) have been involved in autophagy regulation through multiple signaling pathways, and mitochondria, the main source of endogenous ROS, have emerged as essential signal transducers that mediate autophagy. In the present review, we aim to summarize the regulatory function of mitochondria in the autophagic process, particularly regarding the mitochondrial role as the coordination node in the autophagy signaling pathway, involving mitochondrial oxidative stress, and their participation as membrane donors in the initial steps of autophagosome assembly.

MiR-369-3p participates in endometrioid adenocarcinoma via the regulation of autophagy

Background

The aim of this study is to examine miRNA profiling and miR-369-3p participates in endometrioid adenocarcinoma (EEC) via the regulation of autophagy.

Methods

EEC and its adjacent normal tissues were obtained from 20 clinical patients after surgery. MiRNA profiling was performed using next generation sequencing (NGS) and was validated with quantitative real time PCR (qRT-PCR). qRT-PCR was also employed to measure miR-369-3p and autophagy-related protein 10 (ATG10) expression levels. Western blotting assay was performed to measure the expressions of ATG10 and LC3B. Luciferase reporter assay was conducted to confirm the direct targeting of ATG10 by miR-369-3p. Cell proliferation and migration assays were utilized to analyze the role of miR-369-3p in HEC-1-A cells.

Results

We found that miR-369-3p expression levels were down-regulated in EEC compared to the control tissues. The overexpression of miR-369-3p inhibited cell proliferation and migration in EEC; furthermore, ATG10 expression increased in EEC tissues. ATG10 was found to be a potential target of miR-369-3p via a dual-luciferase reporter assay, and ATG10 was shown to be down-regulated by miR-369-3p in protein levels.

Conclusions

This study revealed that miR-369-3p inhibited cell proliferation and migration by targeting ATG10 via autophagy in EEC.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0897-8) contains supplementary material, which is available to authorized users.