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There are 113 results for Autophagy (displaying 21 to 30).

The nuclear cofactor DOR regulates autophagy in mammalian and Drosophila cells

The regulation of autophagy in metazoans is only partly understood, and there is a need to identify the proteins that control this process. The diabetes‐ and obesity‐regulated gene (DOR), a recently reported nuclear cofactor of thyroid hormone receptors, is expressed abundantly in metabolically active tissues such as muscle. Here, we show that DOR shuttles between the nucleus and the cytoplasm, depending on cellular stress conditions, and re‐localizes to autophagosomes on autophagy activation …

DOR moves out of the nucleus in response to the activation of autophagy. (A) The intracellular distribution of DOR is modified by starvation. HeLa cells were transiently transfected with DOR and incubated for 1 h with DMEM (basal), HBSS (starvation), 50 μM chloroquine or 10 mM 3MA. The intracellular localization of DOR was analysed by immunofluorescence and is shown in red. The nuclei are shown in blue (DAPI staining). Scale bars, 10 μm. (B) Endogenous DOR leaves the nucleus under starvation …

CG11347 is required for autophagy activation in the fat body of Drosophila. (A) Decrease of mRNA levels in TubG4, UAS‐CG11347‐RNAi animals compared with TubG4 controls. All measurements were normalized to rp49. *Significant change, P<0.05. (B) Lysotracker staining of fat bodies. No Lysotracker staining is observed in feeding early third‐instar larvae, whereas Lysotracker‐positive granules (red) accumulate in fat body cells of wandering late third‐instar controls (upper panels, TubG4/+). dDOR …

DOR localizes to autophagosomes when autophagy is activated. (A) Confocal images of HeLa cells transiently transfected with DOR and GFP‐LC3, and incubated for 1h with DMEM, HBSS (starvation), 2 μM rapamycin or HBSS containing 50 μM chloroquine. Nuclei were labelled with DAPI. Scale bars, 10 μm. (B,C) Confocal images of HeLa cells transiently transfected with DOR or GFP‐LC3 and incubated with 50 nM Lysotracker in DMEM or HBSS. Scale bars, 10 μm. (D) Confocal images of HeLa cells transiently …

… Macroautophagy (here referred to as autophagy) is an important cellular pathway for the degradation of long‐lived proteins and cytoplasmic organelles ( ; ). A central process in autophagy is the formation of autophagosomes, during which portions of the cytoplasm are surrounded by a membranous structure and then fused with lysosomes to form autolysosomes, in which degradation occurs ( ). Under conditions of extracellular nutrient scarcity, unicellular eukaryotes catabolize cytoplasmic …

Caroline Mauvezin et al. EMBO Reports December 2009

Reactive oxygen species are essential for autophagy and specifically regulate the activity of Atg4

Autophagy is a major catabolic pathway by which eukaryotic cells degrade and recycle macromolecules and organelles. This pathway is activated under environmental stress conditions, during development and in various pathological situations. In this study, we describe the role of reactive oxygen species (ROS) as signaling molecules in starvation‐induced autophagy. We show that starvation stimulates formation of ROS, specifically H 2 O 2 . These oxidative conditions are essential for autophagy

A proposed model for the redox regulation of autophagy.

ROS accumulation is essential for autophagy. (A) Upper panel: CHO cells stably transfected with GFP‐GATE‐16 were preincubated in the presence or absence of 10 mM NAC or 1000 μ/ml catalase for 10 min before starvation for 2 h in the presence or absence of these drugs, or grown in a control medium containing the drugs for 2 h. The cells were then fixed, permeabilized and stained with anti‐GFP monoclonal antibodies. Representative images are shown. Lower panel: HEK 293 cells were transfected …

Autophagy is a major pathway for delivery of proteins and organelles to lysosomes/the vacuole, where they are degraded and recycled. Autophagy plays an essential role in differentiation and development, as well as in cellular response to stress. It is activated during amino‐acid deprivation and has been associated with neurodegenerative diseases, cancer, pathogen infections and myopathies (reviewed in ; ). Autophagy is initiated by the surrounding of cytoplasmic constituents by the crescent …

Ruth Scherz‐Shouval et al. The EMBO Journal April 2007

Mitochondria mediate septin cage assembly to promote autophagy of Shigella

… mitochondrial proteins associate with septins in S. flexneri ‐infected cells. Strikingly, mitochondria associated with S. flexneri promote septin assembly into cages that entrap bacteria for autophagy. We demonstrate that the cytosolic GTP ase dynamin‐related protein 1 (Drp1) interacts with septins to enhance mitochondrial fission. To avoid autophagy, actin‐polymerising Shigella fragment mitochondria to escape from septin caging. Our results demonstrate a role for mitochondria in anti‐ Shigella autophagy and uncover a fundamental link between septin assembly and mitochondria.

… transfected with Mito‐BFP for 24 h, infected with Shigella‐mCherry for 4 h 40 min and processed for CLEM. SEPT6 is shown in green, mitochondria in red and Shigella‐mCherry in blue. Septin cages identified by fluorescent light microscopy (FLM) were processed for TEM. The right‐most image is enlarged from the boxed region in the TEM image and shows the bacterium (Sf) surrounded by a double membrane of autophagy (Au) and the mitochondrial membrane (Mt). The scale bar represents 1 μm. See also Fig EV3B …

… ), surrounding S. flexneri M90T (+M90T) or S. flexneri ΔIcsA (+ΔIcsA) from three independent experiments (analysis of at least 250 measurements per biological replicate). Student's t‐test, ***P < 0.001. A potential model for the Shigella–septin cage and actin tail assembly pathways. Based on our findings, we propose that (i) mitochondria promote septin cage assembly for antibacterial autophagy or (ii) Shigella fragment mitochondria to counteract septin cage entrapment. Depending on the fragmentation of mitochondria by IcsA, Shigella will be compartmentalised in septin cages or spread cell‐to‐cell via actin‐based motility. …

Autophagy was initially characterised as a mechanism for recycling cellular contents in response to nutrient limitation . In recent years, however, it has also been recognised as an important defence mechanism against intracellular bacteria . Bacterial autophagy, similar to autophagy of mitochondria , involves ubiquitin‐binding adaptor proteins such as p62 or NPD52 interacting with LC3 family proteins for autophagosome formation . Relatively little is known about the roles of the cytoskeleton …

Andrea Sirianni et al. EMBO Reports July 2016

Apg10p, a novel protein‐conjugating enzyme essential for autophagy in yeast

Autophagy is a cellular process for bulk degradation of cytoplasmic components. The attachment of Apg12p, a modifier with no significant similarity to ubiquitin, to Apg5p is crucial for autophagy in yeast. This reaction proceeds in a ubiquitination‐like manner, and requires Apg7p and Apg10p. Apg7p exhibits a considerable similarity to ubiquitin‐activating enzyme (E1) and is found to activate Apg12p with ATP hydrolysis. Apg10p, on the other hand, shows no significant similarity to other proteins …

The cysteine‐133 residue of Apg10p is essential for autophagy and the Cvt pathway. (A) Autophagic activities were measured by an ALP assay (Noda and Ohsumi, 1998). YTS3 cells (Δapg10 PHO8::pho8Δ60) harboring each mutant APG10 on CEN plasmids were grown to 1 OD600/ml in SC medium lacking tryptophan and then transferred to SD(−N) medium. Lysates from the cells after incubation for 0 and 4 h were used for assay. Error bars indicate the SD of three independent experiments. (B) Cell lysates from Δapg10 cells (TFD10‐L1) harboring empty vector, pRS316 (lane 1), wild‐type HAAPG10 (lane 2), HAAPG10C26S (lane 3), HAAPG10C133S (lane 4) or HAAPG10C137S (lane 5) on CEN plasmids were subjected to Western blotting analysis with anti‐API antiserum.

… , Ubc9 and Ubc12 are structurally similar to the ubiquitin E2s. Recently, we found a novel modifier essential for autophagy ( ). Autophagy is a cellular process essential for bulk degradation of cytoplasmic components in eukaryotes. We demonstrated previously that cytoplasmic components including proteins, carbohydrates, lipids, nucleic acids and organelles are transported to the vacuole in yeast by macroautophagy in response to nutrient starvation ( ; , ). When cells face nutrient starvation …

Takahiro Shintani et al. The EMBO Journal September 1999

TAK1 activates AMPK‐dependent cytoprotective autophagy in TRAIL‐treated epithelial cells

The capacity of tumour necrosis factor‐related apoptosis‐inducing ligand (TRAIL) to trigger apoptosis preferentially in cancer cells, although sparing normal cells, has motivated clinical development of TRAIL receptor agonists as anti‐cancer therapeutics. The molecular mechanisms responsible for the differential TRAIL sensitivity of normal and cancer cells are, however, poorly understood. Here, we show a novel signalling pathway that activates cytoprotective autophagy in untransformed human …

A schematic presentation of various signalling pathways leading to AMPK activation and AMPK‐dependent autophagy.

IL‐1β activates AMPK and autophagy. (A) Protein lysates from MCF10A cells left untreated (0) or treated with 50 ng/ml TNF, 500 ng/ml TRAIL (positive control) or 10 ng/ml IL‐1β for indicated times were analysed by immunoblotting for phosphorylated ACC (P‐ACC), phosphorylated IκB (P‐IκB) and GAPDH (loading control). The values show the P‐ACC/GAPDH and P‐IkB/GAPDH ratios as percentages of the ratios in untreated cells (left lanes) and are representative of two independent experiments. (B, C …

LKB1 and CaMKKβ do not have an important function in TRAIL‐induced AMPK activation and autophagy. (A) MCF10A–eGFP–LC3 cells were transfected with indicated siRNAs for 48 h and analysed for the indicated mRNAs (top) and proteins (bottom by RT–PCR and immunoblotting, respectively. Similar results were obtained in three independent experiments. (B) MCF10A–eGFP–LC3 cells transfected with indicated siRNAs for 48 h, and left untreated or treated with 500 ng/ml TRAIL for 2 h, 10 μM ionomycin for 24 h …

… Macroautophagy (hereafter referred to as autophagy) is a lysosomal pathway involved in the turnover of long‐lived proteins, cytoplasm and whole organelles ( ; ; ; ). In unstressed cells, autophagy is inhibited by the mammalian target of rapamycin complex 1 (mTORC1). The inhibition of mTORC1 activity (e.g., by starvation or rapamycin) leads to the activation of a set of evolutionarily conserved autophagy‐regulating proteins (Atg proteins) and formation of autophagosomes, which then fuse …

Griselda Herrero‐Martín et al. The EMBO Journal March 2009

Binding of the Atg1/ULK1 kinase to the ubiquitin‐like protein Atg8 regulates autophagy

Autophagy is an intracellular trafficking pathway sequestering cytoplasm and delivering excess and damaged cargo to the vacuole for degradation. The Atg1/ULK1 kinase is an essential component of the core autophagy machinery possibly activated by binding to Atg13 upon starvation. Indeed, we found that Atg13 directly binds Atg1, and specific Atg13 mutations abolishing this interaction interfere with Atg1 function in vivo . Surprisingly, Atg13 binding to Atg1 is constitutive and not altered …

Atg13 binding to Atg1 promotes Cvt and autophagy function, but is not regulated by starvation conditions. (A) Schematic representation of budding yeast Atg13 and alignment of the Atg1‐binding region with homologues from different yeast species. The residues required for Atg1 binding are marked with a grey box. Circled ‘P’ mark known phosphorylation sites on Atg13. N: amino‐terminus; C: carboxy‐terminus. (B) A fragment encompassing amino acids 432–520 of Atg13 (wt) or the corresponding FV mutant …

Autophagy is an important cellular mechanism to eliminate excess or damaged proteins, protein complexes and organelles. This conserved process serves to ensure cellular homeostasis, and plays crucial roles during nutrient starvation and the cellular response to stress conditions, as well as in embryonic development and the defense against several human pathogens. Not surprisingly, defects in autophagy pathways have been associated with numerous human pathologies, including infectious diseases …

Claudine Kraft et al. The EMBO Journal September 2012

TBC1D5 and the AP2 complex regulate ATG9 trafficking and initiation of autophagy

The Rab GAP protein TBC 1D5 controls cellular endomembrane trafficking processes and binds the retromer subunit VPS 29 and the ubiquitin‐like protein ATG 8 ( LC 3). Here, we describe that TBC 1D5 also associates with ATG 9 and the active ULK 1 complex during autophagy. Moreover, ATG 9 and TBC 1D5 interact with clathrin and the AP 2 complex. Depletion of TBC 1D5 leads to missorting of ATG 9 to late endosomes upon activation of autophagy, whereas inhibition of clathrin‐mediated endocytosis or AP …

ACo‐localization of endogenous TBC1D5 and VPS35 with mCherry‐ATG9A, in steady state and autophagy induced by mTOR inhibitor KU0063794 (6 h). B, CQuantification of co‐localization experiments presented in (A). DCo‐immunoprecipitation of HA‐Flag‐TBC1D5 with myc‐VPS29, transiently overexpressed in 293T cells, DMSO or KU0063794 (6 h) treated. E, FCo‐immunoprecipitation of endogenous TBC1D5 and ATG9 with myc‐VPS29 (E) transiently overexpressed in 293T cells or with HA‐Flag‐VPS35 (F) transiently …

… for AP2 and TBC1D5 role in ATG9 trafficking toward autophagosomes. At steady state ATG9 traffics from Golgi to the endosomes and to the plasma membrane. Plasma membrane fraction gets internalized via AP2. During autophagy ATG9‐AP2 vesicles redistribute toward autophagosomes via interaction of TBC1D5 with AP2 and LC3. Data information: Bar graphs (B, D, E), mean ± s.d. n = 3, unpaired two‐tailed t‐test, P‐values: ns P > 0.05, *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001.

… Macroautophagy (autophagy) is a membrane‐dependent process, critical for delivery of various cytoplasmic cargo (e.g., protein aggregates, damaged organelles, and pathogens) to the lysosomes (for degradation) and secretion of molecules that mediate immune responses . Numerous membrane sources are implicated in the formation of autophagosomes: endoplasmic reticulum , mitochondria , plasma membrane , and Golgi complex . This suggests that autophagy closely intersects with and depends on various …

Doris Popovic et al. EMBO Reports April 2014

BAG3 mediates chaperone‐based aggresome‐targeting and selective autophagy of misfolded proteins

Increasing evidence indicates the existence of selective autophagy pathways, but the manner in which substrates are recognized and targeted to the autophagy system is poorly understood. One strategy is transport of a particular substrate to the aggresome, a perinuclear compartment with high autophagic activity. In this paper, we identify a new cellular pathway that uses the specificity of heat‐shock protein 70 (Hsp70) to misfolded proteins as the basis for aggresome‐targeting and autophagic …

Aggresome‐targeted proteins are degraded by autophagy. (A) Analysis of SODG85R‐GFP (green) localization with aggresome marker vimentin, the autophagic receptors p62 and NBR1, the autophagosome marker LC3 and the lysosomal marker LAMP2 (all in red) in BAG3/Hsp70‐transfected HEK cells. Representative merged images of cells with cytoplasmic, pre‐aggresomal and aggresomal SOD distribution are shown. Arrows indicate LC3‐positive autophagosomes. Scale bar, 5 μm. (B) Transmission electron microscope …

… Macroautophagy (referred to as autophagy) is a catabolic process by which cytoplasmic material becomes sequestered in a vesicle—the autophagosome—and shuttled to lysosomes for degradation ( ). Selective autophagy of damaged proteins requires the concentration and isolation of substrates from other cytoplasmic components. Such sequestration occurs in a perinuclear compartment called the aggresome, by retrograde transport of substrates along microtubules through the cytoplasmic dynein motor …

Martin Gamerdinger et al. EMBO Reports January 2011

Nix is a selective autophagy receptor for mitochondrial clearance

Autophagy is the cellular homeostatic pathway that delivers large cytosolic materials for degradation in the lysosome. Recent evidence indicates that autophagy mediates selective removal of protein aggregates, organelles and microbes in cells. Yet, the specificity in targeting a particular substrate to the autophagy pathway remains poorly understood. Here, we show that the mitochondrial protein Nix is a selective autophagy receptor by binding to LC3/GABARAP proteins, ubiquitin‐like modifiers …

… Mounting evidence suggests that selective degradation of bulky cytosolic substrates, such as protein aggregates, damaged organelles and intracellular microbes, is mediated by macroautophagy (autophagy hereafter; ). Its main hallmark is the formation of double‐membrane vesicles—autophagosomes—that engulf cargo and deliver it to lysosomes for degradation ( ; ). Ubiquitination has been proposed as a signal for selective autophagy ( ). Receptor proteins, p62 and neighbour of BRCA1 gene 1 (NBR1 …

Ivana Novak et al. EMBO Reports December 2009

Rab12 regulates mTORC1 activity and autophagy through controlling the degradation of amino‐acid transporter PAT4

Autophagy is an evolutionarily conserved catabolic mechanism that targets intracellular molecules and damaged organelles to lysosomes. Autophagy is achieved by a series of membrane trafficking events, but their regulatory mechanisms are poorly understood. Here, we report small GTPase Rab12 as a new type of autophagic regulator that controls the degradation of an amino‐acid transporter. Knockdown of Rab12 results in inhibition of autophagy and in increased activity of mTORC1 (mammalian …

Rab12 regulates mTORC1 activity and autophagy by controlling the PAT4 protein concentration. (A) Lysates of MEFs transfected with the siRNAs indicated were analysed by immunoblotting with the antibodies indicated. (B) Quantification of the phospho‐S6K levels shown in (A). (C) MEFs transfected with the siRNAs indicated were cultured under nutrient‐rich (N) or starved (S) conditions and were immunostained with anti‐LC3 antibody. The mean numbers of LC3‐positive dots per cell are shown. (D …

Rab12 regulates autophagy. (A) Quantification of the amount of LC3‐II protein in mouse Rab‐knockdown cells. Representative blots are shown in supplementary Fig S1C online. Error bars represent the means and s.e.m. of three independent experiments. (B) Quantification of the amount of p62 protein in candidates Rab‐knockdown cells. Representative blots are shown in supplementary Fig S1D online. Error bars represent the means and s.e.m. of three independent experiments. (C,D) Control and Rab12 …

… Macroautophagy (referred to here as autophagy) is a catabolic process conserved among all eukaryotes. Autophagy not only functions as a nutrient supplier in response to the cellular energy concentration but is also involved in quality control of cellular molecules and organelles, cell defence against infection, embryonic development and various diseases [ ]. Autophagy is achieved by a series of dynamic membrane trafficking events, including isolation membrane/phagophore elongation …

Takahide Matsui et al. EMBO Reports April 2013
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