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There are 113 results for Autophagy (displaying 31 to 40).

Autophagy modulates miRNA‐mediated gene silencing and selectively degrades AIN‐1/GW182 in C. elegans

MicroRNAs (miRNAs) post‐transcriptionally repress gene expression via the miRNA‐induced silencing complex (miRISC), which includes miRNA, Argonaute and a GW182 family member. Here we show that in Caenorhabditis elegans , miRNA‐mediated gene silencing is modulated by macroautophagy, a lysosome‐mediated degradation process. Loss of autophagy activity suppresses developmental defects caused by partially impaired silencing of miRNA targets including the let‐7 family and lsy‐6 . The C. elegans GW182 homolog AIN‐1 is itself selectively degraded by autophagy and colocalizes with the p62 homolog SQST‐1 in autophagy mutants. Thus, autophagy activity modulates miRNA‐mediated gene silencing and degrades a core miRISC component.

Autophagy regulates developmental processes specified by the let‐7 miRNA family and lsy‐6 miRNA. (A–C) Wild‐type and atg‐2 hermaphrodites have a single vulva (arrow). (B) let‐60(n1046gf) mutants show a Muv phenotype. Black arrows indicate pseudovulvae. (D) Loss of autophagy activity suppresses the Muv phenotype in let‐60(n1046) mutants. The number of adult animals examined was: wild type (n=450), let‐60 (n=406), epg‐6; let‐60 (n=444), let‐60; atg‐2 (n=803), epg‐5; let‐60 (n=672), epg‐5; let‐60 …

AIN‐1 is selectively degraded by autophagy. (A,B) AIN‐1::GFP is weakly and diffusely expressed in the cytoplasm during embryogenesis in wild‐type animals. (A) Nomarski image of the embryo shown in (B). Scale bar, 10 μm for whole embryo. C. elegans embryos remain the same size during embryogenesis and loss of autophagy activity has no effect on the embryo size. Thus, scale bars for embryos are only shown once in each figure. (C) AIN‐1::GFP forms a large number of aggregates in epg‐6 mutant …

AIN‐1 colocalizes with SQST‐1 aggregates in autophagy mutants and directly interacts with LGG‐1. (A–D) Both AIN‐1::GFP and SQST‐1, detected by anti‐SQST‐1 antibody, are very weakly expressed and diffusely localized in wild‐type embryos. (E–H) AIN‐1::GFP aggregates colocalize with SQST‐1 aggregates in atg‐3 mutant embryos. Scale bars, 10 μm for insets that show a magnified view. (I–L) AIN‐1::GFP aggregates are separable from PGL granules, detected by anti‐SEPA‐1, in atg‐3 mutant embryos. (M–P …

… asymmetry of the two taste receptor neurons, ASE left (ASEL) and ASE right (ASER) [ ]. lsy‐6 , which is expressed in ASEL, but not in ASER, exerts its effect by repressing the Nkx‐type homeobox gene cog‐1 [ ]. miRNA‐mediated silencing of target genes in these developmental processes has been shown to be modulated by various factors, including the TRIM‐NHL family protein NHL‐2 and Wnt signaling [ ], [ ]. Autophagy is an evolutionarily conserved intracellular degradation process, involving …

Peipei Zhang et al. EMBO Reports June 2013

PLIC proteins or ubiquilins regulate autophagy‐dependent cell survival during nutrient starvation

Ubiquilins (UBQLNs) are adaptor proteins thought to deliver ubiquitinated substrates to proteasomes. Here, we show a role for UBQLN in autophagy: enforced expression of UBQLN protects cells from starvation‐induced death, whereas depletion of UBQLN renders cells more susceptible. The UBQLN protective effect requires the autophagy‐related genes ATG5 and ATG7, two essential components of autophagy. The ubiquitin‐associated domain of UBQLN mediates both its association with autophagosomes and its …

The ubiquilin‐protective effect against starvation requires autophagy. (A) HeLa cells were transfected with siRNAs for autophagy‐related gene ATG5 (siATG5) or with a non‐silencing siRNA (siC). Depletion of ATG5, which decreased the levels of the ATG5–ATG12 covalent complex, was confirmed by Western blot. Loading control: transferrin receptor (TfR). (B) Control or ATG5‐KD cells transfected with UBQLN1 were starved, and the cell viability was assessed as in Fig 1; the graph represents the mean …

Depletion of ubiquilin inhibits the degradation of autophagosomes by lysosomes. (A) Autophagosome subcellular localization during starvation was analysed by microscopy in UBQLN‐ or autophagy‐related gene ATG5‐KD cells expressing GFP‐tagged microtubule associated protein 1 light chain 3 (GFP‐LC3). (B) Autophagosome spatial distribution was quantified by measuring the distance of each LC3 vesicle from the nucleus (in pixels) and by analysing the frequency distribution. (C) Control or UBQLN‐KD …

… the membrane‐bound compartments with which UBQLN associates have not been identified. Autophagic pathways are alternative mechanisms to proteasomes for the degradation of cytoplasmic contents. Macroautophagy (herein called autophagy) allows cells to digest cytoplasmic constituents, including organelles ( ). When autophagy is induced, a double membrane formed in the cytoplasm elongates, surrounds and ultimately seals off a region of the cytoplasm. This compartment, called the autophagosome …

Elsa‐Noah N'Diaye et al. EMBO Reports February 2009

Defects in GABA metabolism affect selective autophagy pathways and are alleviated by mTOR inhibition

In addition to key roles in embryonic neurogenesis and myelinogenesis, γ‐aminobutyric acid ( GABA ) serves as the primary inhibitory mammalian neurotransmitter. In yeast, we have identified a new role for GABA that augments activity of the pivotal kinase, Tor1. GABA inhibits the selective autophagy pathways, mitophagy and pexophagy, through Sch9, the homolog of the mammalian kinase, S6 K 1, leading to oxidative stress, all of which can be mitigated by the Tor1 inhibitor, rapamycin. To confirm …

WT cells were cultured under autophagy conditions with or without GABA for 6 h. S6 phosphorylation after 6 h in SD‐N was analyzed by immunoblotting with a loading control. GFP production monitoring autophagy at the indicated time points was analyzed by immunoblotting.

WT cells expressing OM45‐GFP, along with the uga2∆ strain over‐expressing the GAD1 gene and expressing OM45‐GFP were grown in YPL medium to mid‐log‐phase. To monitor mitophagy, strains were transferred to SD‐N starvation medium (with or without rapamycin). WT strain along with the uga2∆ strain over‐expressing the GAD1 gene was grown in oleate medium and pexophagy was monitored as described in Fig , with or without rapamycin. Samples were taken at the indicated time points, and Pot1 degradation was analyzed by immunoblotting (45 kD). To monitor autophagy, WT cells expressing GFP‐Atg8 along with the uga2∆ strain over‐expressing the GAD1 gene and expressing GFP‐Atg8 were grown in SD medium and transferred to SD‐N.

… the WT strain expressing Rpl25‐GFP in SD medium to mid‐log‐phase and transferring cells to SD‐N either with or without GABA for 24 h. Autophagy was monitored by growing the WT strain expressing GFP‐Atg8 in SD medium to mid‐log‐phase and transferring cells to SD‐N either with or without GABA for 6 h.

… with the disorder (Kim et al , ). However, these symptoms may be secondary to the main cause of the disease. The murine model of SSADH deficiency represents a relevant phenocopy of the human disease, with seizures and evidence of oxidative stress in tissues, along with increased levels of the peroxisomal enzyme catalase in the brain and elevated superoxide dismutase in the brain and liver (Latini et al , ). In the current report, we evaluated the hypothesis that GABA impacts autophagy‐related …

Ronak Lakhani et al. EMBO molecular medicine April 2014

BAX inhibitor‐1 regulates autophagy by controlling the IRE1α branch of the unfolded protein response

Both autophagy and apoptosis are tightly regulated processes playing a central role in tissue homeostasis. Bax inhibitor 1 (BI‐1) is a highly conserved protein with a dual role in apoptosis and endoplasmic reticulum (ER) stress signalling through the regulation of the ER stress sensor inositol requiring kinase 1 α (IRE1α). Here, we describe a novel function of BI‐1 in the modulation of autophagy. BI‐1‐deficient cells presented a faster and stronger induction of autophagy, increasing LC3 flux …

Increased accumulation of autophagosomes and lysosomes in BI‐1‐deficient cells. (A) BI‐1 WT and KO MEFs cells were stably transduced with retroviruses expressing cytochrome b5–GFP to visualize the ER (green). Then cells were stained with lysotracker (red) and observed with a confocal microscope. Nucleus was stained with Hoechst (blue). Scale bar: 30 μm. (B) BI‐1 WT and KO MEFs cells stimulated with EBSS for 3 h to induce autophagy. Acidic vesicles were visualized with a confocal microscope …

BI‐1 deficiency enhances autophagy flux. (A) BI‐1 WT and KO MEFs were treated with EBSS (left panel) or glucose/serum‐free RPMI media (right panel) for the indicated time points. Then, levels of LC3 were determined by western blot analysis. LC3‐I and LC3‐II forms are indicated. Hsp90 levels were assessed as loading control. (B) Quantification of LC3‐II levels relative to Hsp90 expression was performed in several experiments performed as presented in (A). (C) Cells were pre‐treated …

BI‐1 regulates Beclin‐1‐dependent autophagy by controlling JNK activation. (A) BI‐1 WT and KO MEFs were treated with EBSS for 2 h, and the levels of phospho‐p70S6k were determined by western blot analysis. Total p70S6k is also shown. (B) LC3 was monitored by immunofluorescence in cells treated with EBSS for 3 h in the presence or absence of 10 μM JNK inhibitor SP600125. Mean and standard deviation are presented (N=3). Student's t‐test was used to analyse statistical significance, *P<0.001 …

… Macroautophagy, here referred to as autophagy, is a highly conserved and regulated process involved in the catabolism of cytoplasmic components that are recycled to maintain energy production and macromolecule synthesis. Autophagy involves the encapsulation of cargoes into double‐membrane vesicles (autophagosome), which fuse with lysosomes forming the autolysosomes where cargoes are degraded ( ). Under nutrient starvation, autophagy maintains energy homeostasis, but it also regulates tissue …

Karen Castillo et al. The EMBO Journal November 2011

Defective autophagy is a key feature of cerebral cavernous malformations

… have been identified in three genes, KRIT 1 ( CCM 1 ), CCM 2 ( MGC 4607), and PDCD 10 ( CCM 3 ), which occur in both sporadic and familial forms. Autophagy is a bulk degradation process that maintains intracellular homeostasis and that plays essential quality control functions within the cell. Indeed, several studies have identified the association between dysregulated autophagy and different human diseases. Here, we show that the ablation of the KRIT 1 gene strongly suppresses autophagy

… of the mechanisms underlying CCM pathogenesis. Macroautophagy (termed autophagy in this manuscript) is a bulk degradation process that occurs in two primary steps: (i) the sequestration of proteins and organelles into double‐membrane vesicles called autophagosomes and (ii) their subsequent degradation through the fusion of autophagosomes with lysosomes (Xie & Klionsky, ; Feng et al , ). By selectively degrading harmful protein aggregates or damaged organelles, autophagy maintains intracellular …

Saverio Marchi et al. EMBO molecular medicine November 2015

Ubiquilin4 is an adaptor protein that recruits Ubiquilin1 to the autophagy machinery

Ubiquilins (Ubqlns)—a family of ubiquitin‐binding proteins—are involved in several protein degradation pathways and have been implicated in various neurodegenerative diseases. Ubqln1 regulates autophagosome maturation during autophagy‐mediated degradation. We now show that Ubqln4 mediates the interaction between Ubqln1 and the autophagy machinery by recruiting Ubqln1 to LC3. This targeting of Ubqln1 to autophagosomes requires the Ubqln4 UBL domain and the Ubqln1 UBA domain. This study identifies a new role for Ubqln4, expanding the role for Ubqlns in protein degradation.

… Ubiquilins (Ubqlns) are a family of cytosolic proteins that function in protein degradation by carrying cargo to the proteasome, enhancing autophagy‐mediated degradation and participating in endoplasmic reticulum‐associated protein degradation (ERAD) [[ ]. All eukaryotes express Ubqln proteins. While yeast expresses only a single orthologue, Dsk2, there has been an expansion of the family in mammals, and the human genome contains four Ubqln isoforms. Little is known about differences …

Dong Yun Lee et al. EMBO Reports April 2013

Genome‐wide siRNA screen reveals amino acid starvation‐induced autophagy requires SCOC and WAC

Autophagy is a catabolic process by which cytoplasmic components are sequestered and transported by autophagosomes to lysosomes for degradation, enabling recycling of these components and providing cells with amino acids during starvation. It is a highly regulated process and its deregulation contributes to multiple diseases. Despite its importance in cell homeostasis, autophagy is not fully understood. To find new proteins that modulate starvation‐induced autophagy, we performed a genome‐wide …

The role of SCOC and FEZ1 during amino‐acid starvation‐induced autophagy. We show that SCOC bound to FEZ1 is in a complex with ULK1 or UVRAG. Our results suggest that the inhibition of autophagy induction by FEZ1, possibly achieved through inhibition of ULK1 kinase activity or membrane targeting, is relieved by association of SCOC with the ULK1–FEZ1 complex. Also, amino‐acid starvation causes the dissociation of UVRAG from the FEZ1–SCOC complex and this may allow UVRAG to associate …

SCOC is required for autophagy. (A) SCOC is required for autophagy in HEK293 cells. Anti‐ULK1, ‐Actin and ‐LC3 blot after siRNA treatment in HEK293 cells in FM, ES or EL. Representative blot; quantification of LC3II/actin of averaged duplicates; error bars represent s.e.m. (n=3). Significance was determined using a two‐tailed paired t‐test: RF EL versus siSCOC‐03 EL, *P=0.0419. (B) SCOC is required for p62 degradation. p62 levels were determined by western blot (Supplementary Figure S5) after …

Genome‐wide screen for starvation‐induced autophagy. (A) Cellomics images (top) of GFP–LC3‐HEK cells in full medium (FM) or after 2 h in starvation medium (ES) with leupeptin (EL). Scale bars=40 μm. Optimised automated analysis (bottom left) programme detecting hoechst‐labelled nuclei (purple line), cell outline (red line) and identifies GFP–LC3 spots (red spots) in FM and EL. Enlarged GFP–LC3 images in FM and EL (bottom right). Scale bars=10 μm. (B) SCPO, STIPO and STAPO after indicated siRNA …

… Macroautophagy (here autophagy) is an essential, conserved degradative pathway that has a role in cell homeostasis in normal conditions, eliminating damaged organelles or misfolded proteins. Autophagy‐deficient mice die immediately after birth ( ), and defects in autophagy have been linked to multiple diseases including neurodegenerative disorders such as Huntington's disease, cancer and immune diseases ( ). Autophagy is also induced in response to amino‐acid deprivation or external stress …

Nicole C McKnight et al. The EMBO Journal April 2012

Antagonism of Beclin 1‐dependent autophagy by BCL‐2 at the endoplasmic reticulum requires NAF‐1

In addition to mitochondria, BCL‐2 is located at the endoplasmic reticulum (ER) where it is a constituent of several distinct complexes. Here, we identify the BCL‐2‐interacting protein at the ER, nutrient‐deprivation autophagy factor‐1 (NAF‐1)—a bitopic integral membrane protein whose defective expression underlies the aetiology of the neurodegenerative disorder Wolfram syndrome 2 (WFS2). NAF‐1 contains a two iron–two sulphur coordinating domain within its cytosolic region, which is necessary …

NAF‐1 knockdown results in increased incidence and intensity of starvation‐induced Beclin 1‐dependent autophagy. (A) Effect of NAF‐1 knockdown on starvation‐induced autophagy. H1299 cells infected with CTRL or NAF‐1 shRNA were starved for 4 h in EBSS with DMSO (vehicle) or Baf A1 (100 nM). Cell lysates were analysed by immunoblot. (B) Representative images of GFP‐LC3 staining in H1299 GFP‐LC3 cells transfected with LUC or NAF‐1 siRNA, untreated and starved. Scale bar represents 10 μm. (C …

NAF‐1 does not affect BIK‐initiated apoptosis, but influences BIK‐induced autophagy in the absence of caspase activation. (A) H1299 neo and HA‐BCL‐2b5 cells treated with control (CTRL) or NAF‐1 shRNA were either mock infected or infected with Ad‐BIK in the absence or presence of 50 μM zVAD‐fmk. Cell lysates were analysed by immunoblot. (B) Caspase activity was measured using the fluorescent substrate DEVD‐AMC. The results represent the average±s.d. of three independent experiments. (C …

BCL‐2 inhibition of Beclin 1‐dependent autophagy requires NAF‐1. (A) NAF‐1 contributes to the interaction between BCL‐2 and Beclin 1. H1299 HA‐BCL‐2b5 cells were transfected with Flag‐Beclin 1 and either LUC or NAF‐1 siRNA. Cells were lysed and subjected to immunoprecipitation with anti‐BCL‐2 antibody. Precipitates were subjected to analysis by immunoblot using anti‐Beclin 1 and anti‐BCL‐2. All lanes are derived from the same gel and of the same exposure. Thin white lines indicate where lanes …

… ) that associates with Beclin 1 and other accessory proteins to generate a functional PI3K complex ( ), thus resulting in enrichment of PI(3)P at this ER‐associated site ( ). The exact topography of the assembly of the PI3K complex at this site, however, remains to be determined. Beclin 1 is a haploinsufficient tumour suppressor and an important effector of autophagy, whose antagonism can be achieved by BCL‐2 that is located at the ER ( ; ). Beclin 1 contains a BH3 domain that contributes to its …

Natasha C Chang et al. The EMBO Journal February 2010

Ral GTPase and the exocyst regulate autophagy in a tissue‐specific manner

Autophagy traffics cellular components to the lysosome for degradation. Ral GTP ase and the exocyst have been implicated in the regulation of stress‐induced autophagy, but it is unclear whether they are global regulators of this process. Here, we investigate Ral function in different cellular contexts in Drosophila and find that it is required for autophagy during developmentally regulated cell death in salivary glands, but does not affect starvation‐induced autophagy in the fat body …

… Macroautophagy (autophagy) is a catabolic process during which cytoplasmic components, including organelles and long‐lived proteins, are engulfed and trafficked to the lysosomal compartment for degradation . Autophagy has been implicated in several diseases, including neurodegeneration and cancer . Autophagy plays dual roles to determine cell fate depending on cell context . During stress, such as nutrient deprivation or growth factor removal, autophagy promotes cellular homeostasis …

Kirsten Tracy et al. EMBO Reports January 2016

PAQR3 controls autophagy by integrating AMPK signaling to enhance ATG14L‐associated PI3K activity

The Beclin1–VPS34 complex is recognized as a central node in regulating autophagy via interacting with diverse molecules such as ATG14L for autophagy initiation and UVRAG for autophagosome maturation. However, the underlying molecular mechanism that coordinates the timely activation of VPS34 complex is poorly understood. Here, we identify that PAQR3 governs the preferential formation and activation of ATG14L‐linked VPS34 complex for autophagy initiation via two levels of regulation. Firstly …

… analysis, followed by IB. IVPS34 complexes immunopurified with Beclin1 or ATG14L antibody in mouse liver were subjected to a quantitative PI(3)P ELISA. JA schematic model of PAQR3 regulation on autophagy in response to glucose starvation. Data information: Values are presented as mean ± SD (n = 7 for each group (E, F); n = 5 (I); **P < 0.01).

Autophagy (macroautophagy) is an evolutionarily conserved intracellular degradation process in which entire organelles, lipid vesicles, or protein aggregates are engulfed in autophagosome and eventually digested in lysosomes by acidic hydrolases (Galluzzi et al , ). Autophagy is not only crucial for removal of misfolded proteins and turnover of organelles for cellular homeostasis, but also important for survival of eukaryotic cells under stress conditions, development, tumorigenesis …

Da‐Qian Xu et al. The EMBO Journal March 2016
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