Autophagy and proteins involved in vesicular trafficking

The phospholamban R14del generates pathogenic aggregates by impairing autophagosome-lysosome fusion

Phospholamban (PLN) plays a crucial role in regulating sarcoplasmic reticulum (SR) Ca2+ cycling and cardiac contractility. Mutations within the PLN gene have been detected in patients with cardiomyopathy, with the heterozygous variant c.40_42delAGA (p.R14del) of PLN being the most prevalent. Investigations into the mechanisms underlying the pathology of PLN-R14del have revealed that cardiac cells from affected patients exhibit pathological aggregates containing PLN. Herein, we performed comprehensive molecular and cellular analyses to delineate the molecular aberrations associated with the formation of these aggregates. We determined that PLN aggregates contain autophagic proteins, indicating inefficient degradation via the autophagy pathway. Our findings demonstrate that the expression of PLN-R14del results in diminished autophagic flux due to impaired fusion between autophagosomes and lysosomes. Mechanistically, this defect is linked to aberrant recruitment of key membrane fusion proteins to autophagosomes, which is mediated in part by changes in Ca2+ homeostasis. Collectively, these results highlight a novel function of PLN-R14del in regulating autophagy, that may contribute to the formation of pathogenic aggregates in patients with cardiomyopathy. Prospective strategies tailored to ameliorate impaired autophagy may hold promise against PLN-R14del disease.

A distinct metabolic and epigenetic state drives trained immunity in HSC-derived macrophages from autoimmune mice

Here, we investigate the contribution of long-term hematopoietic stem cells (HSCsLT) to trained immunity (TI) in the setting of chronic autoimmune disease. Using a mouse model of systemic lupus erythematosus (SLE), we show that bone marrow-derived macrophages (BMDMs) from autoimmune mice exhibit hallmark features of TI, including increased Mycobacterium avium killing and inflammatory cytokine production, which are mechanistically linked to increased glycolytic metabolism. We show that HSCs from autoimmune mice constitute a transplantable, long-term reservoir for macrophages that exhibit the functional properties of TI. However, these BMDMs exhibit reduced glycolytic activity and chromatin accessibility at metabolic genes while retaining elevated expression of TI-associated transcriptional regulators. Hence, HSC exposed to autoimmune inflammation can give rise to macrophages in which the functional and metabolic properties of TI are decoupled. Our data support a model in which TI is characterized by a spectrum of molecular and metabolic states driving augmented immune function.

Dysregulation of autophagy in gastric carcinoma: Pathways to tumor progression and resistance to therapy

The considerable death rates and lack of symptoms in early stages of gastric cancer (GC) make it a major health problem worldwide. One of the most prominent risk factors is infection with Helicobacter pylori. Many biological processes, including those linked with cell death, are disrupted in GC. The cellular "self-digestion" mechanism necessary for regular balance maintenance, autophagy, is at the center of this disturbance. Misregulation of autophagy, however, plays a role in the development of GC. In this review, we will examine how autophagy interacts with other cell death processes, such as apoptosis and ferroptosis, and how it affects the progression of GC. In addition to wonderful its role in the epithelial-mesenchymal transition, it is engaged in GC metastasis. The role of autophagy in GC in promoting drug resistance stands out. There is growing interest in modulating autophagy for GC treatment, with research focusing on natural compounds, small-molecule inhibitors, and nanoparticles. These approaches could lead to breakthroughs in GC therapy, offering new hope in the fight against this challenging disease.

Possible Regulation of P-Glycoprotein Function by Adrenergic Agonists II: Study with Isolated Rat Jejunal Sheets and Caco-2 Cell monolayers

To clarify the regulation of drug absorption by the enteric nervous system, we investigated how adrenergic agonists (adrenaline (ADR), clonidine (CLO), dobutamine (DOB)) and dibutyryl cAMP (DBcAMP) affected P-glycoprotein (P-gp) function by utilizing isolated rat jejunal sheets and Caco-2 cell monolayers. ADR and CLO significantly decreased the secretory transport (Papptotal) of rhodamine-123 and tended to decrease the transport via P-gp (PappP-gp) and passive transport (Papppassive). In contrast, DBcAMP significantly increased and DOB tended to increase Papptotal and both tended to increase PappP-gpand Papppassive. Changes in P-gp expression on brush border membrane by adrenergic agonists and DBcAMP were significantly correlated with PappP-gp, while P-gp expression was not changed in whole cell homogenates, suggesting that the trafficking of P-gp would be responsible for its functional changes. Papppassive was inversely correlated with transmucosal or transepithelial electrical resistance, indicating that adrenergic agonists affected the paracellular permeability. Adrenergic agonists also changed cAMP levels, which were significantly correlated with PappP-gp. Furthermore, protein kinase A (PKA) or PKC inhibitor significantly decreased PappP-gp in Caco-2 cell monolayers, suggesting that they would partly contribute to the changes in P-gp activity. In conclusion, adrenergic agonists regulated P-gp function and paracellular permeability, which would be caused via adrenoceptor stimulation.

High water temperature raised the requirements of methionine for spotted seabass (Lateolabrax maculatus)

This study evaluated the effects of dietary methionine level and rearing water temperature on growth, antioxidant capacity, methionine metabolism, and hepatocyte autophagy in spotted seabass (Lateolabrax maculatus). A factorial design was used with six methionine levels [0.64, 0.85, 1.11, 1.33, 1.58, and 1.76%] and two temperatures [moderate temperature (MT): 27 ℃, and high temperature (HT): 33 ℃]. The results revealed the significant effects of both dietary methionine level and water temperature on weight gain (WG) and feed efficiency (FE), and their interaction effect was found on WG (P < 0.05). In both water temperatures tested, fish WG increased with increasing methionine level up to 1.11% and decreased thereafter. The groups of fish reared at MT exhibited dramatically higher WG and FE than those kept at HT while an opposite trend was observed for feed intake. Liver antioxidant indices including reduced glutathione and malondialdehyde (MDA) concentrations, and catalase and superoxide dismutase (SOD) activities remarkably increased in the HT group compared to the MT group. Moreover, the lowest MDA concentration and the highest SOD activity were recorded at methionine levels between 1.11% and 0.85%, respectively, regardless of water temperatures. Expression of methionine metabolism-related key enzyme genes (mat2b, cbs, ms, and bhmt) in the liver was increased at moderate methionine levels, and higher expression levels were detected at MT compared to HT with the exception of ms gene relative expression. Relative expression of hepatocyte autophagy-related genes (pink1, atg5, mul1, foxo3) and hsp70 was upregulated by increasing methionine level up to a certain level and decreased thereafter and increasing water temperature led to significantly enhanced expression of hsp70. In summary, HT induced heat stress and reduced fish growth, and an appropriate dietary methionine level improved the antioxidant capacity and stress resistance of fish. A second-order polynomial regression analysis based on the WG suggested that the optimal dietary methionine level for maximum growth of spotted seabass is 1.22% of the diet at 27 ℃ and 1.26% of the diet at 33 ℃, then 1.37 g and 1.68 g dietary methionine intake is required for 100 g weight gain at 27 ℃ or 33 ℃, respectively.

Unraveling the Janus-Faced Role of Autophagy in Hepatocellular Carcinoma: Implications for Therapeutic Interventions

This review aims to provide a comprehensive understanding of the molecular mechanisms underlying autophagy and mitophagy in hepatocellular carcinoma (HCC). Autophagy is an essential cellular process in maintaining cell homeostasis. Still, its dysregulation is associated with the development of liver diseases, including HCC, which is one of leading causes of cancer-related death worldwide. We focus on elucidating the dual role of autophagy in HCC, both in tumor initiation and progression, and highlighting the complex nature involved in the disease. In addition, we present a detailed analysis of a small subset of autophagy- and mitophagy-related molecules, revealing their specific functions during tumorigenesis and the progression of HCC cells. By understanding these mechanisms, we aim to provide valuable insights into potential therapeutic strategies to manipulate autophagy effectively. The goal is to improve the therapeutic response of liver cancer cells and overcome drug resistance, providing new avenues for improved treatment options for HCC patients. Overall, this review serves as a valuable resource for researchers and clinicians interested in the complex role of autophagy in HCC and its potential as a target for innovative therapies aimed to combat this devastating disease.

The role of sphingosine-1-phosphate in autophagy and related disorders

S1P, also referred to as sphingosine-1-phosphate, is a lipid molecule with bioactive properties involved in numerous cellular processes such as cell growth, movement, programmed cell death, self-degradation, cell specialization, aging, and immune system reactions. Autophagy is a meticulously controlled mechanism in which cells repurpose their elements to maintain cellular balance. There are five stages in autophagy: initiation, nucleation, elongation and maturation, fusion, and degradation. New research has provided insight into the complex connection between S1P and autophagy, uncovering their interaction in both normal and abnormal circumstances. Gaining knowledge about the regulatory mechanism of S1P signaling on autophagy can offer a valuable understanding of its function in well-being and illness, potentially leading to innovative therapeutic concepts for diverse ailments. Hence, this review analyzes the essential stages in mammalian autophagy, with a specific emphasis on recent research exploring the control of each stage by S1P. Additionally, it sheds light on the roles of S1P-induced autophagy in various disorders.

Cogs in the autophagic machine-equipped to combat dementia-prone neurodegenerative diseases

Neurodegenerative diseases are often characterized by hydrophobic inclusion bodies, and it may be the case that the aggregate-prone proteins that comprise these inclusion bodies are in fact the cause of neurotoxicity. Indeed, the appearance of protein aggregates leads to a proteostatic imbalance that causes various interruptions in physiological cellular processes, including lysosomal and mitochondrial dysfunction, as well as break down in calcium homeostasis. Oftentimes the approach to counteract proteotoxicity is taken to merely upregulate autophagy, measured by an increase in autophagosomes, without a deeper assessment of contributors toward effective turnover through autophagy. There are various ways in which autophagy is regulated ranging from the mammalian target of rapamycin (mTOR) to acetylation status of proteins. Healthy mitochondria and the intracellular energetic charge they preserve are key for the acidification status of lysosomes and thus ensuring effective clearance of components through the autophagy pathway. Both mitochondria and lysosomes have been shown to bear functional protein complexes that aid in the regulation of autophagy. Indeed, it may be the case that minimizing the proteins associated with the respective neurodegenerative pathology may be of greater importance than addressing molecularly their resulting inclusion bodies. It is in this context that this review will dissect the autophagy signaling pathway, its control and the manner in which it is molecularly and functionally connected with the mitochondrial and lysosomal system, as well as provide a summary of the role of autophagy dysfunction in driving neurodegenerative disease as a means to better position the potential of rapamycin-mediated bioactivities to control autophagy favorably.

Modulation of cellular autophagy by genotype 1 hepatitis E virus ORF3 protein

Hepatitis E virus (HEV) egresses from infected hepatocytes as quasienveloped particles containing open reading frame 3 (ORF3) protein. HEV ORF3 (small phosphoprotein) interacts with host proteins to establish a favourable environment for virus replication. It is a functional viroporin that plays an important role during virus release. Our study provides evidence that pORF3 plays a pivotal role in inducing Beclin1-mediated autophagy that helps HEV-1 replication as well as its exit from cells. The ORF3 interacts with host proteins involved in regulation of transcriptional activity, immune response, cellular and molecular processes, and modulation of autophagy, by interacting with proteins, DAPK1, ATG2B, ATG16L2 and also several histone deacetylases (HDACs). For autophagy induction, the ORF3 utilizes non-canonical NF-κB2 pathway and sequesters p52NF-κB and HDAC2 to upregulate DAPK1 expression, leading to enhanced Beclin1 phosphorylation. By sequestering several HDACs, HEV may prevent histone deacetylation to maintain overall cellular transcription intact to promote cell survival. Our findings highlight a novel crosstalk between cell survival pathways participating in ORF3-mediated autophagy.

mTOR signaling regulates Zika virus replication bidirectionally through autophagy and protein translation

Zika virus (ZIKV) reemerged in 2016 and attracted much more attention worldwide. To date, the limited knowledge of ZIKV interactions with host cells in the early stages of infection impedes the prevention of viral epidemics and the treatment of ZIKV disease. The mammalian target of rapamycin (mTOR) signaling pathway plays an essential role in the regulation of autophagy and protein synthesis during multiple viral infections. This study aimed to investigate the functional role of mTOR signaling in ZIKV replication in human umbilical vein endothelial cells. Immunoblotting demonstrated that ZIKV infection inhibited mTORC1 signaling, enhancing autophagy but obstructing protein translation. Drugs or siRNA for interfering with mTOR signaling molecules were utilized to demonstrate that AKT/TSC2/mTORC1 signaling was involved in ZIKV infection and that autophagy promoted ZIKV production, but viral protein expression was regulated by mTORC1 signaling. Moreover, confocal microscopy indicated a robust correlation between autophagy and viral RNA transcription. This study clarifies the dual functions of mTOR signaling during ZIKV infection and provides theoretical support for developing potential anti-ZIKV drugs based on mTOR signaling molecules and deeper insights to better understand the mechanism between ZIKV and host cells.

FKBP8 is a novel molecule that participates in the regulation of the autophagic pathway

Autophagy is a homeostatic process by which misfolded proteins, organelles and cytoplasmic material are engulfed in autophagosomal vesicles and degraded through a lisosomal pathway. FKBP8 is a member of the FK506-binding proteins family (FKBP) usually found in mitochondria and the endoplasmic reticulum. This protein plays a critical role in cell functions such as protein trafficking and folding. In the present report we demonstrate that the depletion of FKBP8 abrogated autophagy activation induced by starvation, whereas the overexpression of this protein triggered the autophagy cascade. We found that FKBP8 co-localizes with ATG14L and BECN1, both members of the VPS34 lipid kinase complex, which regulates the initial steps in the autophagosome formation process. We have also demonstrated that FKBP8 is necessary for VPS34 activity. Our findings indicate that the regulatory function of FKBP8 in the autophagy process depends of its transmembrane domain. Surprisingly, this protein was not found in autophagosomal vesicles, which reinforces the notion that the FKBP8 only participates in the initial steps of the autophagosome formation process. Taken together, our data provide evidence that FKBP8 modulates the early steps of the autophagosome formation event by interacting with the VPS34 lipid kinase complex. SUMMARY: In this article, the protein FKBP38 is reported to be a novel modulator of the initial steps of the autophagic pathway, specifically in starvation-induced autophagy. FKBP38 interacts with the VPS34 lipid kinase complex, with the transmembrane domain of FKBP38 being critical for its biological function.

Interphase Protein Layers Formed on Self-Assembled Monolayers in Crowded Biological Environments: Analysis by Surface Force and Quartz Crystal Microbalance Measurements

We investigated a viscous protein layer formed on self-assembled monolayers (SAMs) in crowded biological environments. The results were obtained through force spectroscopic measurements using colloidal probes and substantiated by exhaustive analysis using a quartz crystal microbalance with an energy dissipation technique. A hydrophobic SAM of n-octanethiol (C8 SAM) in bovine serum albumin (BSA) solution is buried under an adlayer of denatured BSA molecules and an additional viscous interphase layer that is five times more viscous than the bulk solution. C8 SAMs in fetal bovine serum induced a formation of a thicker adsorbed protein layer but with no observable viscous interphase layer. These findings show that a fouling surface is essentially inaccessible to any approaching molecules and thus has a new biological and physical identity arising from its surrounding protein layers. In contrast, the SAMs composed of sulfobetaine-terminated alkanethiol proved to be sufficiently protein-resistant and bio-inert even under crowded conditions due to a protective barrier of its interfacial water, which has implications in the accurate targeting of artificial particles for drug delivery and similar applications by screening any non-specific interactions. Finally, our strategies provide a platform for the straightforward yet effectual in vitro characterization of diverse types of surfaces in the context of targeted interactions in crowded biological environments.

Autophagy activation, lipotoxicity and lysosomal membrane permeabilization synergize to promote pimozide- and loperamide-induced glioma cell death

Increasing evidence suggests that induction of lethal macroautophagy/autophagy carries potential significance for the treatment of glioblastoma (GBM). In continuation of previous work, we demonstrate that pimozide and loperamide trigger an ATG5- and ATG7 (autophagy related 5 and 7)-dependent type of cell death that is significantly reduced with cathepsin inhibitors and the lipid reactive oxygen species (ROS) scavenger α-tocopherol in MZ-54 GBM cells. Global proteomic analysis after treatment with both drugs also revealed an increase of proteins related to lipid and cholesterol metabolic processes. These changes were accompanied by a massive accumulation of cholesterol and other lipids in the lysosomal compartment, indicative of impaired lipid transport/degradation. In line with these observations, pimozide and loperamide treatment were associated with a pronounced increase of bioactive sphingolipids including ceramides, glucosylceramides and sphingoid bases measured by targeted lipidomic analysis. Furthermore, pimozide and loperamide inhibited the activity of SMPD1/ASM (sphingomyelin phosphodiesterase 1) and promoted induction of lysosomal membrane permeabilization (LMP), as well as release of CTSB (cathepsin B) into the cytosol in MZ-54 wild-type (WT) cells. Whereas LMP and cell death were significantly attenuated in ATG5 and ATG7 knockout (KO) cells, both events were enhanced by depletion of the lysophagy receptor VCP (valosin containing protein), supporting a pro-survival function of lysophagy under these conditions. Collectively, our data suggest that pimozide and loperamide-driven autophagy and lipotoxicity synergize to induce LMP and cell death. The results also support the notion that simultaneous overactivation of autophagy and induction of LMP represents a promising approach for the treatment of GBM.Abbreviations: ACD: autophagic cell death; AKT1: AKT serine/threonine kinase 1; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG14: autophagy related 14; CERS1: ceramide synthase 1; CTSB: cathepsin B; CYBB/NOX2: cytochrome b-245 beta chain; ER: endoplasmatic reticulum; FBS: fetal bovine serum; GBM: glioblastoma; GO: gene ontology; HTR7/5-HT7: 5-hydroxytryptamine receptor 7; KD: knockdown; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LAP: LC3-associated phagocytosis; LMP: lysosomal membrane permeabilization; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MTOR: mechanistic target of rapamycin kinase; RB1CC1: RB1 inducible coiled-coil 1; ROS: reactive oxygen species; RPS6: ribosomal protein S6; SMPD1/ASM: sphingomyelin phosphodiesterase 1; VCP/p97: valosin containing protein; WT: wild-type.

Advances in the genetic classification of amyotrophic lateral sclerosis

PURPOSE OF REVIEW

Amyotrophic lateral sclerosis (ALS) is an archetypal complex disease wherein disease risk and severity are, for the majority of patients, the product of interaction between multiple genetic and environmental factors. We are in a period of unprecedented discovery with new large-scale genome-wide association study (GWAS) and accelerating discovery of risk genes. However, much of the observed heritability of ALS is undiscovered and we are not yet approaching elucidation of the total genetic architecture, which will be necessary for comprehensive disease subclassification.

RECENT FINDINGS

We summarize recent developments and discuss the future. New machine learning models will help to address nonlinear genetic interactions. Statistical power for genetic discovery may be boosted by reducing the search-space using cell-specific epigenetic profiles and expanding our scope to include genetically correlated phenotypes. Structural variation, somatic heterogeneity and consideration of environmental modifiers represent significant challenges which will require integration of multiple technologies and a multidisciplinary approach, including clinicians, geneticists and pathologists.

SUMMARY

The move away from fully penetrant Mendelian risk genes necessitates new experimental designs and new standards for validation. The challenges are significant, but the potential reward for successful disease subclassification is large-scale and effective personalized medicine.

Autophagy Drives Galectin-1 Secretion From Tumor-Associated Macrophages Facilitating Hepatocellular Carcinoma Progression

Galectin-1 (Gal-1) is a secretory lectin with pro-tumor activities and is associated strongly with hepatocellular carcinoma (HCC) development. Although Gal-1 is a well-known soluble pro-tumor factor in the tumor microenvironment (TME), the secretion mode of Gal-1 is not clearly defined. On the other hand, in addition to cancer cells, Gal-1 is widely expressed in tumor stromal cells, including tumor-associated macrophages (TAMs). TAMs are a significant component of stromal cells in TME; however, their contributions in producing Gal-1 to TME are still not explored. Here we reveal that TAMs can actively secrete Gal-1 in response to stimuli of HCC cells. Gal-1 produced by TAMs leads to an increase of the systemic level of Gal-1 and HCC tumor growth in mice. Mechanistically, TLR2-dependent secretory autophagy is found to be responsible for Gal-1 secretion from TAMs. Gal-1 acts as a cargo of autophagosomes to fuse with multivesicular bodies via Rab11 and VAMP7-mediated vesicle trafficking before being secreted. This autophagy-regulated Gal-1 secretion in TAMs correlates to poor overall survival and progression-free survival rates of HCC patients. Our findings uncover the secretion mode of Gal-1 via secretory autophagy and highlight the pathological role of TAM-produced Gal-1 in HCC progression.

Possible Regulation of P-glycoprotein Function by Adrenergic Agonists in a Vascular-luminal Perfused Preparation of Small Intestine

Although the functions of small intestine are largely regulated by enteric nervous system (ENS), an independent intrinsic innervation, as well as central nervous system (CNS), the neural regulation of drug absorption from the small intestine still remains to be clarified. To obtain some information on it, the effect of adrenergic agonists on P-glycoprotein (P-gp) function was investigated by utilizing a vascular-luminal perfused rat small intestine. Adrenaline significantly decreased the secretion of rhodamine-123 (R-123) into the intestinal lumen, but dibutyryl cAMP (DBcAMP) significantly enhanced R-123 secretion. The inhibition study with quinidine clearly indicated that the decrease in secretory clearance of R-123 by adrenaline or the increase by DBcAMP would be attributed to the decrease or increase in P-gp activity, respectively. Expression levels of P-gp in whole mucosal homogenates were not changed at all by any chemicals examined, but those on brush border membrane (BBM) of intestinal epithelial cells were significantly decreased or increased by adrenaline or DBcAMP, respectively. Furthermore, changes in P-gp activity caused by adrenergic agonists and DBcAMP were significantly correlated with changes in expression level of P-gp in BBM, suggesting that the trafficking of P-gp from cytosolic pool to BBM would be regulated by adrenergic agonists and DBcAMP.

Entamoeba histolytica exploits the autophagy pathway in macrophages to trigger inflammation in disease pathogenesis

The mechanism whereby Entamoeba histolytica (Eh) binding with macrophages at the intercellular junction triggers aggressive pro-inflammatory responses in disease pathogenesis is not well understood. The host intracellular protein degradation process autophagy and its regulatory proteins are involved in maintenance of cellular homeostasis and excessive inflammatory responses. In this study we unraveled how Eh hijacks the autophagy process in macrophages to dysregulate pro-inflammatory responses. Direct contact of live Eh with macrophages activated caspase-6 that induced rapid proteolytic degradation of the autophagy ATG16L1 protein complex independent of NLRP3 inflammasome and caspase-3/8 activation. Crohn's disease susceptible ATG16L1 T300A variant was highly susceptible to Eh-mediated degradation that augmented pro-inflammatory cytokines in mice. Quantitative proteomics revealed downregulation of autophagy and vesicle-mediated transport and upregulation of cysteine-type endopeptidase pathways in response to Eh. We conclude during Eh-macrophage outside-in signaling, ATG16L1 protein complex plays an overlooked regulatory role in shaping the pro-inflammatory landscape in amebiasis.

Subcellular Distribution of Dietary Methyl-Mercury in Gammarus fossarum and Its Impact on the Amphipod Proteome

The transfer of methyl-Hg (MeHg) from food is central for its effects in aquatic animals, but we still lack knowledge concerning its impact on invertebrate primary consumers. In aquatic environments, cell walls of plants are particularly recalcitrant to degradation and as such remain available as a food source for long periods. Here, the impact at the proteomic level of dietary MeHg in Gammarus fossarum was established and linked to subcellular distribution of Hg. Individuals of G. fossarum were fed with MeHg in cell wall or intracellular compartments of Elodea nuttallii. Hg concentrations in subcellular fractions were 2 to 6 times higher in animals fed with cell wall than intracellular compartments. At the higher concentrations tested, the proportion of Hg in metal-sensitive fraction increased from 30.0 ± 6.1 to 41.0 ± 5.7% for individuals fed with intracellular compartment, while biologically detoxified metal fraction increased from 30.0 ± 6.1 to 50.0 ± 2.8% when fed with cell wall compartment. Data suggested that several thresholds of proteomic response are triggered by increased bioaccumulation in each subcellular fraction in correlation with Hg exclusively bound to the metal-sensitive fraction, while the increase of biologically detoxified metal likely had a cost for fitness. Proteomics analysis supported that the different binding sites and speciation in shoots subsequently resulted in different fate and cellular toxicity pathways to consumers. Our data confirmed that Hg bound in cell walls of plants can be assimilated by G. fossarum, which is consistent with its feeding strategy, hence pointing cell walls as a significant source for Hg transfers and toxicity in primary consumers. The high accumulation of Hg in macrophytes makes them a risk for food web transfer in shallow ecosystems. The present results allowed gaining new insights into the effects and uptake mechanisms of MeHg in aquatic primary consumers.

Mutant-TMEM230-induced neurodegeneration and impaired axonal mitochondrial transport

Parkinson's disease (PD) is a neurodegenerative disease with movement disorders including resting tremor, rigidity, bradykinesia and postural instability. Recent studies have identified a new PD associated gene, TMEM230 (transmembrane protein 230). However, the pathological roles of TMEM230 and its variants are not fully understood. TMEM230 gene encodes two protein isoforms. Isoform2 is the major protein form (~95%) in human. In this study, we overexpress isoform2 TMEM230 variants (WT or PD-linked *184Wext*5 mutant) or knockdown endogenous protein in cultured SH-5Y5Y cells and mouse primary hippocampus neurons to study their pathological roles. We found that overexpression of WT and mutant TMEM230 or knockdown of endogenous TMEM230-induced neurodegeneration and impaired mitochondria transport at the retrograde direction in axons. Mutant TMEM230 caused more severe neurotoxicity and mitochondrial transport impairment than WT-TMEM230 did. Our results demonstrate that maintaining TMEM230 protein levels is critical for neuron survival and axon transport. These findings suggest that mutant-TMEM230-induced mitochondrial transport impairment could be the early event leading to neurite injury and neurodegeneration in PD development.

Liver X Receptor Alpha Activation Inhibits Autophagy and Lipophagy in Hepatocytes by Dysregulating Autophagy-Related 4B Cysteine Peptidase and Rab-8B, Reducing Mitochondrial Fuel Oxidation

BACKGROUND AND AIMS

Fat accumulation results from increased fat absorption and/or defective fat metabolism. Currently, the lipid-sensing nuclear receptor that controls fat utilization in hepatocytes is elusive. Liver X receptor alpha (LXRα) promotes accumulation of lipids through the induction of several lipogenic genes. However, its effect on lipid degradation is open for study. Here, we investigated the inhibitory role of LXRα in autophagy/lipophagy in hepatocytes and the underlying basis.

APPROACH AND RESULTS

In LXRα knockout mice fed a high-fat diet, or cell models, LXRα activation suppressed the function of mitochondria by inhibiting autophagy/lipophagy and induced hepatic steatosis. Gene sets associated with "autophagy" were enriched in hepatic transcriptome data. Autophagy flux was markedly augmented in the LXRα knockout mouse liver and primary hepatocytes. Mechanistically, LXRα suppressed autophagy-related 4B cysteine peptidase (ATG4B) and Rab-8B, responsible for autophagosome and -lysosome formation, by inducing let-7a and microRNA (miR)-34a. Chromatin immunoprecipitation assay enabled us to find LXRα as a transcription factor of let-7a and miR-34a. Moreover, 3' untranslated region luciferase assay substantiated the direct inhibitory effects of let-7a and miR-34a on ATG4B and Rab-8B. Consistently, either LXRα activation or the let-7a/miR-34a transfection lowered mitochondrial oxygen consumption rate and mitochondrial transmembrane potential and increased fat levels. In obese animals or nonalcoholic fatty liver disease (NAFLD) patients, let-7a and miR-34a levels were elevated with simultaneous decreases in ATG4B and Rab-8B levels.

CONCLUSIONS

LXRα inhibits autophagy in hepatocytes through down-regulating ATG4B and Rab-8B by transcriptionally activating microRNA let-7a-2 and microRNA 34a genes and suppresses mitochondrial biogenesis and fuel consumption. This highlights a function of LXRα that culminates in the progression of liver steatosis and steatohepatitis, and the identified targets may be applied for a therapeutic strategy in the treatment of NAFLD.

Regulatory Function of Sympathetic Innervation on the Endo/Lysosomal Trafficking of Acetylcholine Receptor

Recent studies have demonstrated that neuromuscular junctions are co-innervated by sympathetic neurons. This co-innervation has been shown to be crucial for neuromuscular junction morphology and functional maintenance. To improve our understanding of how sympathetic innervation affects nerve–muscle synapse homeostasis, we here used in vivo imaging, proteomic, biochemical, and microscopic approaches to compare normal and sympathectomized mouse hindlimb muscles. Live confocal microscopy revealed reduced fiber diameters, enhanced acetylcholine receptor turnover, and increased amounts of endo/lysosomal acetylcholine-receptor-bearing vesicles. Proteomics analysis of sympathectomized skeletal muscles showed that besides massive changes in mitochondrial, sarcomeric, and ribosomal proteins, the relative abundance of vesicular trafficking markers was affected by sympathectomy. Immunofluorescence and Western blot approaches corroborated these findings and, in addition, suggested local upregulation and enrichment of endo/lysosomal progression and autophagy markers, Rab 7 and p62, at the sarcomeric regions of muscle fibers and neuromuscular junctions. In summary, these data give novel insights into the relevance of sympathetic innervation for the homeostasis of muscle and neuromuscular junctions. They are consistent with an upregulation of endocytic and autophagic trafficking at the whole muscle level and at the neuromuscular junction.

Ammonium stress increases microautophagic activity while impairing macroautophagic flux in Arabidopsis roots

Plant responses to NH₄⁺ stress are complex, and multiple mechanisms underlying NH₄⁺ sensitivity and tolerance in plants may be involved. Here, we demonstrate that macro- and microautophagic activities are oppositely affected in plants grown under NH₄⁺ toxicity conditions. When grown under NH₄⁺ stress conditions, macroautophagic activity was impaired in roots. Root cells accumulated autophagosomes in the cytoplasm, but showed less autophagic flux, indicating that late steps of the macroautophagy process are affected under NH₄⁺ stress conditions. Under this scenario, we also found that the CCZ1-MON1 complex, a critical factor for vacuole delivery pathways, functions in the late step of the macroautophagic pathway in Arabidopsis. In contrast, an accumulation of tonoplast-derived vesicles was observed in vacuolar lumens of root cells of NH₄⁺ -stressed plants, suggesting the induction of a microautophagy-like process. In this sense, some SYP22-, but mainly VAMP711-positive vesicles were observed inside vacuole in roots of NH₄⁺ -stressed plants. Consistent with the increased tonoplast degradation and the reduced membrane flow to the vacuole due to the impaired macroautophagic flux, the vacuoles of root cells of NH₄⁺ -stressed plants showed a simplified structure and lower tonoplast content. Taken together, this study presents evidence that postulates late steps of the macroautophagic process as a relevant physiological mechanism underlying the NH₄⁺ sensitivity response in Arabidopsis, and additionally provides insights into the molecular tools for studying microautophagy in plants.

Autophagy in the cancer-immunity dialogue

Autophagy is quintessential for the maintenance of cellular homeostasis in all eukaryotic cells, explaining why both normal and malignant cells benefit from proficient autophagic responses. Moreover, autophagy is intimately involved in the immunological control of malignant transformation, tumor progression and response to therapy. However, the net effect of autophagy activation or inhibition on the natural growth or therapeutic response of tumors evolving in immunocompetent hosts exhibits a considerable degree of context dependency. Here, we discuss the complex cross-talk between autophagy and immuno-oncology as delineated by genetic and pharmacological approaches in mouse models of cancer.

The Macro-Autophagy-Related Protein Beclin-1 Immunohistochemical Expression Correlates With Tumor Cell Type and Clinical Behavior of Uveal Melanoma

Uveal melanoma, in spite of its rarity, represents the most common primitive intraocular malignant neoplasm of the adults; it affects choroid, ciliary bodied and iris and remains clinically silent for a long time, being accidentally discovered by routine ophthalmic exams. Prognosis of uveal melanoma is poor and frequently characterized by liver metastases, within 10-15 years from diagnosis. Autophagy is a multi-step catabolic process by which cells remove damaged organelles and proteins and recycle nutrients. It has been hypothesized that in early stages of tumorigenesis autophagy has a tumor suppressor role while, in more advanced stages, it may represent a survival mechanism of neoplastic cells in response to stress. Several proteins related to autophagy cascade have been investigated in numerous subtypes of human cancer, with overall controversal results. In this paper we studied the immunohistochemical expression of 3 autophagy related proteins (Beclin-1, p62 and ATG7) in a cohort of 85 primary uveal melanoma treated by primary enucleation (39 with metastasis and 46 non metastatic) and correlated their expression with clinico-pathological parameters and blood vascular microvessel density, in order to investigate the potential prognostic role of autophagy in this rare neoplasm. We found that high immunohistochemical levels of Beclin-1 correlated with a lower risk of metastasis and higher disease-free survival times, indicating a positive prognostic role for Beclin-1 in uveal melanoma. No statistically significative differences regarding the expression of ATG7 and p62 between metastatic and non metastatic patients was detected.

Rab GTPases in Osteoclastic Bone Resorption and Autophagy

Small guanosine triphosphate hydrolases (GTPases) of the Rab family are involved in plasma membrane delivery, fusion events, and lysosomal and autophagic degradation pathways, thereby regulating signaling pathways and cell differentiation and function. Osteoclasts are bone-resorbing cells that maintain bone homeostasis. Polarized vesicular trafficking pathways result in the formation of the ruffled border, the osteoclast’s resorptive organelle, which also assists in transcytosis. Here, we reviewed the different roles of Rab GTPases in the endomembrane machinery of osteoclasts and in bone diseases caused by the dysfunction of these proteins, with a particular focus on autophagy and bone resorption. Understanding the molecular mechanisms underlying osteoclast-related bone disease development is critical for developing and improving therapies.

Targeted suppression of soybean BAG6-induced cell death in yeast by soybean cyst nematode effectors

While numerous effectors that suppress plant immunity have been identified from bacteria, fungi, and oomycete pathogens, relatively little is known for nematode effectors. Several dozen effectors have been reported from the soybean cyst nematode (SCN). Previous studies suggest that a hypersensitive response-like programmed cell death is triggered at nematode feeding sites in soybean during an incompatible interaction. However, virulent SCN populations overcome this incompatibility using unknown mechanisms. A soybean BAG6 (Bcl-2 associated anthanogene 6) gene previously reported by us to be highly up-regulated in degenerating feeding sites induced by SCN in a resistant soybean line was attenuated in response to a virulent SCN population. We show that GmBAG6-1 induces cell death in yeast like its Arabidopsis homolog AtBAG6 and also in soybean. This led us to hypothesize that virulent SCN may target GmBAG6-1 as part of their strategy to overcome soybean defence responses during infection. Thus, we used a yeast viability assay to screen SCN effector candidates for their ability to specifically suppress GmBAG6-1-induced cell death. We identified several effectors that strongly suppressed cell death mediated by GmBAG6-1. Two effectors identified as suppressors showed direct interaction with GmBAG6-1 in yeast, suggesting that one mechanism of cell death suppression may occur through an interaction with this host protein.

The flavonoids of Sophora flavescens exerts anti-inflammatory activity via promoting autophagy of Bacillus Calmette-Guérin-stimulated macrophages

Tuberculosis (TB), a highly infectious air-borne disease, has remained a global health problem. Conventional treatment and preventions such as antibiotics and Bacilli Calmette-Guerin (BCG) vaccine can be unreliable. In view of the increasing prevalence of anti-TB drug resistance, adjunctive therapy may be necessary to shorten the recovery time. We have previously shown that flavonoids in the medicinal herb Sophora flavescens exhibit anti-inflammatory and bactericidal activities. The aim of this study was to investigate the molecular and cellular characteristics of flavonoids of S. flavescens (FSF) in BCG-stimulated macrophages for assessing their roles in anti-inflammation and autophagy. Mouse alveolar macrophage (MH-S) cell line and primary mouse peritoneal macrophages were stimulated in vitro with heat-inactivated BCG and treated with FSF, with or without autophagy inhibitor Bafilomycin A1 (BafA1). Gene expression was analyzed using quantitative PCR, and cytokine/chemokine release was analyzed by Milliplex assay and ELISA. Autophagy-related proteins were quantified by Western blot and flow cytometry, and autophagolysosomes were detected using fluorescence microscopy. In both MH-S cell line and mouse peritoneal macrophages stimulated by heat-inactivated BCG, FSF was found to up-regulate autophagy-related proteins microtubule-associated protein 1A/1B-light chain 3 (LC3) and protein 62 (p62), and suppress the induced proinflammatory cytokine TNF-α, CCL5, and IL-6. FSF actively modulates immune processes through suppressing BCG-mediated inflammation by promoting autophagy in MH-S cells and mouse peritoneal macrophages. We suggest that FSF may be useful as an adjunctive therapeutic agent for TB infection by modulating cell survival through autophagy and reducing inflammation.

Vesicular transport mediates the uptake of cytoplasmic proteins into mitochondria in Drosophila melanogaster

Mitochondrial aging, which results in mitochondrial dysfunction, is strongly linked to many age-related diseases. Aging is associated with mitochondrial enlargement and transport of cytosolic proteins into mitochondria. The underlying homeostatic mechanisms that regulate mitochondrial morphology and function, and their breakdown during aging, remain unclear. Here, we identify a mitochondrial protein trafficking pathway in Drosophila melanogaster involving the mitochondria-associated protein Dosmit. Dosmit induces mitochondrial enlargement and the formation of double-membraned vesicles containing cytosolic protein within mitochondria. The rate of vesicle formation increases with age. Vesicles originate from the outer mitochondrial membrane as observed by tracking Tom20 localization, and the process is mediated by the mitochondria-associated Rab32 protein. Dosmit expression level is closely linked to the rate of ubiquitinated protein aggregation, which are themselves associated with age-related diseases. The mitochondrial protein trafficking route mediated by Dosmit offers a promising target for future age-related mitochondrial disease therapies.

Mitochondrial dynamics change during ageing, with larger mitochondria and altered protein import in older animals. Here the authors show that Dosmit protein mediates mitochondrial morphology with Rab32 by inducing double-membraned vesicles that regulate protein trafficking into mitochondria.

SPIB promotes anoikis resistance via elevated autolysosomal process in lung cancer cells

Anoikis (detachment-induced cell death) is a specific type of programmed cell death which occurs in response to the loss of the correct extracellular matrix connections. Anoikis resistance is an important mechanism in cancer invasiveness and metastatic behavior. Autophagy, on the other hand, involves the degradation of damaged organelles and the recycling of misfolded proteins and intracellular components. However, the intersection of these two cellular responses in lung cancer cells has not been extensively studied. Here, we identified that upon matrix deprivation, the lymphocyte lineage-specific Ets transcription factor SPIB was activated and directly enhanced SNAP47 transcription in certain lung cancer cells. Loss of attachment-induced autophagy significantly increased anoikis resistance by SPIB activation. Consistent with this function, SPIB depletion by short hairpin RNA abrogated SNAP47 transcriptional activation upon matrix deprivation. Therefore, these data delineate an important role of SPIB in autophagy-mediated anoikis resistance in lung cancer cells. Accordingly, these findings suggest that manipulating SPIB-regulated pathways in vivo and evaluating the impact of anoikis resistance warrant further investigation. DATABASE: RNA sequencing and ChIP sequencing data are available in Gene Expression Omnibus database under the accession numbers GSE106592 and GSE125561, respectively.

Assessing Autophagy in Archived Tissue or How to Capture Autophagic Flux from a Tissue Snapshot

Autophagy is a highly conserved degradation mechanism that is essential for maintaining cellular homeostasis. In human disease, autophagy pathways are frequently deregulated and there is immense interest in targeting autophagy for therapeutic approaches. Accordingly, there is a need to determine autophagic activity in human tissues, an endeavor that is hampered by the fact that autophagy is characterized by the flux of substrates whereas histology informs only about amounts and localization of substrates and regulators at a single timepoint. Despite this challenging task, considerable progress in establishing markers of autophagy has been made in recent years. The importance of establishing clear-cut autophagy markers that can be used for tissue analysis cannot be underestimated. In this review, we attempt to summarize known techniques to quantify autophagy in human tissue and their drawbacks. Furthermore, we provide some recommendations that should be taken into consideration to improve the reliability and the interpretation of autophagy biomarkers in human tissue samples.

Redox homeostasis, oxidative stress and mitophagy

Autophagy is a ubiquitous homeostatic mechanism for the degradation or turnover of cellular components. Degradation of mitochondria via autophagy (mitophagy) is involved in a number of physiological processes including cellular homeostasis, differentiation and aging. Upon stress or injury, mitophagy prevents the accumulation of damaged mitochondria and the increased steady state levels of reactive oxygen species leading to oxidative stress and cell death. A number of human diseases, particularly neurodegenerative disorders, have been linked to the dysregulation of mitophagy. In this mini-review, we aimed to review the molecular mechanisms involved in the regulation of mitophagy and their relationship with redox signaling and oxidative stress.

SNARE proteins rescue impaired autophagic flux in Down syndrome

Down syndrome (DS) is a chromosomal disorder caused by trisomy of chromosome 21 (Ts21). Unbalanced karyotypes can lead to dysfunction of the proteostasis network (PN) and disrupted proteostasis is mechanistically associated with multiple DS comorbidities. Autophagy is a critical component of the PN that has not previously been investigated in DS. Based on our previous observations of PN disruption in DS, we investigated possible dysfunction of the autophagic machinery in human DS fibroblasts and other DS cell models. Following induction of autophagy by serum starvation, DS fibroblasts displayed impaired autophagic flux indicated by autophagolysosome accumulation and elevated p62, NBR1, and LC3-II abundance, compared to age- and sex-matched, euploid (CTL) fibroblasts. While lysosomal physiology was unaffected in both groups after serum starvation, we observed decreased basal abundance of the Soluble N-ethylmaleimide-sensitive-factor Attachment protein Receptor (SNARE) family members syntaxin 17 (STX17) and Vesicle Associated Membrane Protein 8 (VAMP8) indicating that decreased autophagic flux in DS is due at least in part to a possible impairment of autophagosome-lysosome fusion. This conclusion was further supported by the observation that over-expression of either STX17 or VAMP8 in DS fibroblasts restored autophagic degradation and reversed p62 accumulation. Collectively, our results indicate that impaired autophagic clearance is a characteristic of DS cells that can be reversed by enhancement of SNARE protein expression and provides further evidence that PN disruption represents a candidate mechanism for multiple aspects of pathogenesis in DS and a possible future target for therapeutic intervention.

Centrosome Amplification in Cancer Disrupts Autophagy and Sensitizes to Autophagy Inhibition

Centrosome amplification (CA), or a numerical increase in centrosomes, is common in human cancers, particularly those with high-risk features. We have discovered that cells with CA have an increased burden of autophagy, a catabolic process whereby autophagosomes engulf damaged organelles and proteins and deliver these contents to the lysosome for degradation and subsequent recycling. Cells with CA demonstrate an accumulation of autophagosomes. We evaluated the alternative hypotheses that CA alters autophagy by modulating microtubule networks and impairing trafficking versus altering lysosome clustering and organization versus chromosome missegregation-induced proteotoxic stress. Using LC3 reporter assays and autophagosome tracking experiments, we demonstrate that CA causes an accumulation of autophagosomes by interfering with autophagosome trafficking. To establish whether this was a druggable weakness, we tested autophagy inhibitors in our cell models of CA. Cells with CA are sensitized to chemical and genetic autophagy inhibition. Taken together, our results suggest that autophagy is disrupted by CA and sensitizes cells to inhibition of autophagy. These findings suggest a novel precision medicine strategy, whereby CA increases reliance on autophagy and serves as a biomarker for autophagy inhibitors in high-risk cancers. IMPLICATIONS: Our study suggests that CA could be used as a predictive biomarker for treatment with autophagy inhibitors.

Activation of the macroautophagy pathway by Yersinia enterocolitica promotes intracellular multiplication and egress of yersiniae from epithelial cells

The virulence strategy of pathogenic Yersinia spp. involves cell-invasive as well as phagocytosis-preventing tactics to enable efficient colonisation of the host organism. Enteropathogenic yersiniae display an invasive phenotype in early infection stages, which facilitates penetration of the intestinal mucosa. Here we show that invasion of epithelial cells by Yersinia enterocolitica is followed by intracellular survival and multiplication of a subset of ingested bacteria. The replicating bacteria were enclosed in vacuoles with autophagy-related characteristics, showing phagophore formation, xenophagy, and recruitment of cytoplasmic autophagosomes to the bacteria-containing compartments. The subsequent fusion of these vacuoles with lysosomes and concomitant vesicle acidification were actively blocked by Yersinia. This resulted in increased intracellular proliferation and detectable egress of yersiniae from infected cells. Notably, deficiency of the core autophagy machinery component FIP200 impaired the development of autophagic features at Yersinia-containing vacuoles as well as intracellular replication and release of bacteria to the extracellular environment. These results suggest that Y. enterocolitica may take advantage of the macroautophagy pathway in epithelial cells to create an autophagosomal niche that supports intracellular bacterial survival, replication, and, eventually, spread of the bacteria from infected cells.

Junín Virus Promotes Autophagy To Facilitate the Virus Life Cycle

Junín virus (JUNV), a member of the family Arenaviridae, is the etiological agent of Argentine hemorrhagic fever (AHF), a potentially deadly endemic-epidemic disease affecting the population of the most fertile farming land of Argentina. Autophagy is a degradative process with a crucial antiviral role; however, several viruses subvert the pathway to their benefit. We determined the role of autophagy in JUNV-infected cells by analyzing LC3, a cytoplasmic protein (LC3-I) that becomes vesicle membrane associated (LC3-II) upon induction of autophagy. Cells overexpressing enhanced green fluorescent protein (EGFP)-LC3 and infected with JUNV showed an increased number of LC3 punctate structures, similar to those obtained after starvation or bafilomycin A1 treatment, which leads to autophagosome induction or accumulation, respectively. We also monitored the conversion of LC3-I to LC3-II, observing LC3-II levels in JUNV-infected cells similar to those observed in starved cells. Additionally, we kinetically studied the number of LC3 dots after JUNV infection and found that the virus activated the pathway as early as 2 h postinfection (p.i.), whereas the UV-inactivated virus did not induce the pathway. Cells subjected to starvation or pretreated with rapamycin, a pharmacological autophagy inductor, enhanced virus yield. Also, we assayed the replication capacity of JUNV in Atg5 knockout or Beclin 1 knockdown cells (both critical components of the autophagic pathway) and found a significant decrease in JUNV replication. Taken together, our results constitute the first study indicating that JUNV infection induces an autophagic response, which is functionally required by the virus for efficient propagation.IMPORTANCE Mammalian arenaviruses are zoonotic viruses that cause asymptomatic and persistent infections in their rodent hosts but may produce severe and lethal hemorrhagic fevers in humans. Currently, there are neither effective therapeutic options nor effective vaccines for viral hemorrhagic fevers caused by human-pathogenic arenaviruses, except the vaccine Candid no. 1 against Argentine hemorrhagic fever (AHF), licensed for human use in areas of endemicity in Argentina. Since arenaviruses remain a severe threat to global public health, more in-depth knowledge of their replication mechanisms would improve our ability to fight these viruses. Autophagy is a lysosomal degradative pathway involved in maintaining cellular homeostasis, representing powerful anti-infective machinery. We show, for the first time for a member of the family Arenaviridae, a proviral role of autophagy in JUNV infection, providing new knowledge in the field of host-virus interaction. Therefore, modulation of virus-induced autophagy could be used as a strategy to block arenavirus infections.

Anopheles aquasalis transcriptome reveals autophagic responses to Plasmodium vivax midgut invasion

Background

Elimination of malaria depends on mastering transmission and understanding the biological basis of Plasmodium infection in the vector. The first mosquito organ to interact with the parasite is the midgut and its transcriptomic characterization during infection can reveal effective antiplasmodial responses able to limit the survival of the parasite. The vector response to Plasmodium vivax is not fully characterized, and its specificities when compared with other malaria parasites can be of fundamental interest for specific control measures.

Methods

Experimental infections were performed using a membrane-feeding device. Three groups were used: P. vivax-blood-fed, blood-fed on inactivated gametocytes, and unfed mosquitoes. Twenty-four hours after feeding, the mosquitoes were dissected and the midgut collected for transcriptomic analysis using RNAseq. Nine cDNA libraries were generated and sequenced on an Illumina HiSeq2500. Readings were checked for quality control and analysed using the Trinity platform for de novo transcriptome assembly. Transcript quantification was performed and the transcriptome was functionally annotated. Differential expression gene analysis was carried out. The role of the identified mechanisms was further explored using functional approaches.

Results

Forty-nine genes were identified as being differentially expressed with P. vivax infection: 34 were upregulated and 15 were downregulated. Half of the P. vivax-related differentially expressed genes could be related to autophagy; therefore, the effect of the known inhibitor (wortmannin) and activator (spermidine) was tested on the infection outcome. Autophagic activation significantly reduced the intensity and prevalence of infection. This was associated with transcription alterations of the autophagy regulating genes Beclin, DRAM and Apg8.

Conclusions

Our data indicate that P. vivax invasion of An. aquasalis midgut epithelium triggers an autophagic response and its activation reduces infection. This suggests a novel mechanism that mosquitoes can use to fight Plasmodium infection.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3506-8) contains supplementary material, which is available to authorized users.

Molecular interplay of autophagy and endocytosis in human health and diseases

Autophagy, an evolutionarily conserved process for maintaining the physio-metabolic equilibrium of cells, shares many common effector proteins with endocytosis. For example, tethering proteins involved in fusion like Ras-like GTPases (Rabs), soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs), lysosomal-associated membrane protein (LAMP), and endosomal sorting complex required for transport (ESCRT) have a dual role in endocytosis and autophagy, and the trafficking routes of these processes converge at lysosomes. These common effectors indicate an association between budding and fusion of membrane-bound vesicles that may have a substantial role in autophagic lysosome reformation, by sensing cellular stress levels. Therefore, autophagy-endocytosis crosstalk may be significant and implicates a novel endocytic regulatory pathway of autophagy. Moreover, endocytosis has a pivotal role in the intake of signalling molecules, which in turn activates cascades that can result in pathophysiological conditions. This review discusses the basic mechanisms of this crosstalk and its implications in order to identify potential novel therapeutic targets for various human diseases.

Autophagy in Zika Virus Infection: A Possible Therapeutic Target to Counteract Viral Replication

Zika virus (ZIKV) still constitutes a public health concern, however, no vaccines or therapies are currently approved for treatment. A fundamental process involved in ZIKV infection is autophagy, a cellular catabolic pathway delivering cytoplasmic cargo to the lysosome for degradation—considered as a primordial form of innate immunity against invading microorganisms. ZIKV is thought to inhibit the Akt-mTOR signaling pathway, which causes aberrant activation of autophagy promoting viral replication and propagation. It is therefore appealing to study the role of autophagic molecular effectors during viral infection to identify potential targets for anti-ZIKV therapeutic intervention.

Targeting cholesterol metabolism in glioblastoma: a new therapeutic approach in cancer therapy

Glioblastoma multiforme (GBM) is the most aggressive malignant brain tumor known with a poor survival rate despite current advances in the field of cancer. Additional research into the pathophysiology of GBM is urgently needed given the devastating nature of this disease. Recent studies have revealed the unique cellular physiology of GBM cells as compared with healthy astrocytes. Intriguingly, GBM cells are incapable of de novo cholesterol synthesis via the mevalonate pathway. Thus, the survival of GBM cells depends on cholesterol uptake via low-density lipoprotein receptors (LDLRs) in the form of apolipoprotein-E-containing lipoproteins and ATP-binding cassette transporter A1 (ABCA1) that efflux surplus cholesterol out of cells. Liver X receptors regulate intracellular cholesterol levels in neurons and healthy astrocytes through changes in the expression of LDLR and ABCA1 in response to cholesterol and its derivatives. In GBM cells, due to the dysregulation of this surveillance pathway, there is an accumulation of intracellular cholesterol. Furthermore, intracellular cholesterol regulates temozolomide-induced cell death in glioblastoma cells via accumulation and activation of death receptor 5 in plasma membrane lipid rafts. The mevalonate pathway and autophagy flux are also fundamentally related with implications for cell health and death. Thus, via cholesterol metabolism, the mevalonate pathway may be a crucial player in the pathogenesis and treatment of GBM where our current understanding is still lacking. Targeting cholesterol metabolism in GBM may hold promise as a novel adjunctive clinical therapy for this devastating cancer.

Autophagy and GLUT4: The missing pieces

BACKGROUND

Autophagy is a process devoted to degrade and recycle cellular components inside mammalian cells through lysosomal system. It plays a main function in the pathophysiology of several diseases. In type 2 diabetes, works demonstrated the dual functions of autophagy in diabetes biology. Studies had approved the role of autophagy in promoting different routes for movement of integral membrane proteins to the plasma membrane. But its role in regulation of GLUT4 trafficking has not been widely observed. In normal conditions, insulin promotes GLUT4 translocation from intracellular membrane compartments to the plasma membrane, while in type 2 diabetes defects occur in this translocation.

METHOD

Intriguing evidences discussed the contribution of different intracellular compartments in autophagy membrane formation. Furthermore, autophagy serves to mobilise membranes within cells, thereby promoting cytoplasmic components reorganisation. The intent of this review is to focus on the possibility of autophagy to act as a carrier for GLUT4 through regulating GLUT4 endocytosis, intracellular trafficking in different compartments, and translocation to cell membrane.

RESULTS

The common themes of autophagy and GLUT4 have been highlighted. The review discussed the overlapping of endocytosis mechanism and intracellular compartments, and has shown that autophagy and GLUT4 utilise similar proteins (SNAREs) which are used for exocytosis. On top of that, PI3K and AMPK also control both autophagy and GLUT4.

CONCLUSION

The control of GLUT4 trafficking through autophagy could be a promising field for treating type 2 diabetes.

Rab GTPases in Osteoclastic Endomembrane Systems

Osteoclasts (OCs) are bone-resorbing cells that maintain bone homeostasis. OC differentiation, survival, and activity are regulated by numerous small GTPases, including those of the Rab family, which are involved in plasma membrane delivery and lysosomal and autophagic degradation pathways. In resorbing OCs, polarized vesicular trafficking pathways also result in formation of the ruffled membrane, the resorbing organelle, and in transcytosis.

Autophagy as a pharmacological target in hematopoiesis and hematological disorders

Autophagy is involved in many cellular processes, including cell homeostasis, cell death/survival balance and differentiation. Autophagy is essential for hematopoietic stem cell survival, quiescence, activation and differentiation. The deregulation of this process is associated with numerous hematological disorders and pathologies, including cancers. Thus, the use of autophagy modulators to induce or inhibit autophagy emerges as a potential therapeutic approach for treating these diseases and could be particularly interesting for differentiation therapy of leukemia cells. This review presents therapeutic strategies and pharmacological agents in the context of hematological disorders. The pros and cons of autophagy modulators in therapy will also be discussed.

"Get the Balance Right": Pathological Significance of Autophagy Perturbation in Neuromuscular Disorders

Recent research has revealed that autophagy, a major catabolic process in cells, is dysregulated in several neuromuscular diseases and contributes to the muscle wasting caused by non-muscle disorders (e.g. cancer cachexia) or during aging (i.e. sarcopenia). From there, the idea arose to interfere with autophagy or manipulate its regulatory signalling to help restore muscle homeostasis and attenuate disease progression. The major difficulty for the development of therapeutic strategies is to restore a balanced autophagic flux, due to the dynamic nature of autophagy. Thus, it is essential to better understand the mechanisms and identify the signalling pathways at play in the control of autophagy in skeletal muscle. A comprehensive analysis of the autophagic flux and of the causes of its dysregulation is required to assess the pathogenic role of autophagy in diseased muscle. Furthermore, it is essential that experiments distinguish between primary dysregulation of autophagy (prior to disease onset) and impairments as a consequence of the pathology. Of note, in most muscle disorders, autophagy perturbation is not caused by genetic modification of an autophagy-related protein, but rather through indirect alteration of regulatory signalling or lysosomal function. In this review, we will present the mechanisms involved in autophagy, and those ensuring its tight regulation in skeletal muscle. We will then discuss as to how autophagy dysregulation contributes to the pathogenesis of neuromuscular disorders and possible ways to interfere with this process to limit disease progression.

Roles for RAB24 in autophagy and disease

Autophagy is an evolutionarily conserved degradation pathway for cells to maintain homeostasis, produce energy, degrade misfolded proteins and damaged organelles, and fight against intracellular pathogens. The process of autophagy entails the isolation of cytoplasmic cargo into double membrane bound autophagosomes that undergo maturation by fusion with endosomes and lysosomes to obtain degradation capacity. RAB proteins regulate intracellular vesicle trafficking events including autophagy. RAB24 is an atypical RAB protein that is required for the clearance of late autophagic vacuoles under basal conditions. RAB24 has also been connected to several diseases including ataxia, cancer and tuberculosis. This review gives a short summary on autophagy and RAB proteins, and an overview on the current knowledge on the roles of RAB24 in autophagy and disease.

The down-regulated ING5 expression in lung cancer: a potential target of gene therapy

ING5 can interact with p53, thereby inhibiting cell growth and inducing apoptosis. We found that ING5 overexpression not only inhibited proliferation, migration, and invasion, but also induced G2 arrest, differentiation, autophagy, apoptosis, glycolysis and mitochondrial respiration in lung cancer cells. ING5 transfection up-regulated the expression of Cdc2, ATG13, ATG14, Beclin-1, LC-3B, AIF, cytochrome c, Akt1/2/3, ADFP, PFK-1 and PDPc, while down-regulated the expression of Bcl-2, XIAP, survivin,β-catenin and HXK1. ING5 transfection desensitized cells to the chemotherapy of MG132, paclitaxel, and SAHA, which paralleled with apoptotic alteration. ING5 overexpression suppressed the xenograft tumor growth by inhibiting proliferation and inducing apoptosis. ING5 expression level was significantly higher in normal tissue than that in lung cancer at both protein and mRNA levels. Nuclear ING5 expression was positively correlated with ki-67 expression and cytoplasmic ING5 expression. Cytoplasmic ING5 expression was positively associated with lymph node metastasis, and negatively with age, lymphatic invasion or CPP32 expression. ING5 expression was different in histological classification: squamous cell carcinoma > adenocarcinoma > large cell carcinoma > small cell carcinoma. Taken together, our data suggested that ING5 downregulation might involved in carcinogenesis, growth, and invasion of lung cancer and could be considered as a promising marker to gauge the aggressiveness of lung cancer. It might be employed as a potential target for gene therapy of lung cancer.

Protection of macrophages from intracellular pathogens by miR-182-5p mimic-a gene expression meta-analysis approach

The goals of this study were to (a) define which host genes are of particular importance during the interactions between macrophages and intracellular pathogens, and (b) use this knowledge to gain fresh, experimental understanding of how macrophage activities may be manipulated during host defense. We designed an in silico method for meta-analysis of microarray gene expression data, and used this to combine data from 16 different studies of cells in the monocyte-macrophage lineage infected with seven different pathogens. Three thousand four hundred ninety-eight genes were identified, which we call the macrophage intracellular pathogen response (macIPR) gene set. As expected, the macIPR gene set showed a strong bias toward genes previously associated with the immune response. Predicted target sites for miR-182-5p (miR-182) were strongly over-represented among macIPR genes, indicating an unexpected role for miR-182-regulatable genes during intracellular pathogenesis. We therefore transfected primary human alveolar macrophage-like monocyte-derived macrophages from multiple different donors with synthetic miR-182, and found that miR-182 overexpression (a) increases proinflammatory gene induction during infection with Francisella tularensis live vaccine strain (LVS), (b) primes macrophages for increased autophagy, and (c) enhances macrophage control of both gram negative F. tularensisLVS and gram positive Bacillus anthracisANR-1 spores. These data therefore suggest a new application for miR-182 in promoting resistance to intracellular pathogens.