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Autophagy Dec 2021The gene is localized on the X-chromosome and variants in this gene are linked to six different neurodegenerative disorders, i.e., ß-propeller protein associated... (Review)
Review
The gene is localized on the X-chromosome and variants in this gene are linked to six different neurodegenerative disorders, i.e., ß-propeller protein associated neurodegeneration, Rett-like syndrome, intellectual disability, and epileptic encephalopathies including developmental and epileptic encephalopathy, early-onset epileptic encephalopathy and West syndrome and potentially also specific malignancies. WDR45/WIPI4 is a WD-repeat β-propeller protein that belongs to the WIPI (WD repeat domain, phosphoinositide interacting) family. The precise cellular function of WDR45 is still largely unknown, but deletions or conventional variants in can lead to macroautophagy/autophagy defects, malfunctioning mitochondria, endoplasmic reticulum stress and unbalanced iron homeostasis, suggesting that this protein functions in one or more pathways regulating directly or indirectly those processes. As a result, the underlying cause of the WDR45-associated disorders remains unknown. In this review, we summarize the current knowledge about the cellular and physiological functions of WDR45 and highlight how genetic variants in its encoding gene may contribute to the pathophysiology of the associated diseases. In particular, we connect clinical manifestations of the disorders with their potential cellular origin of malfunctioning and critically discuss whether it is possible that one of the most prominent shared features, i.e., brain iron accumulation, is the primary cause for those disorders. ATG/Atg: autophagy related; BPAN: ß-propeller protein associated neurodegeneration; CNS: central nervous system; DEE: developmental and epileptic encephalopathy; EEG: electroencephalograph; ENO2/neuron-specific enolase, enolase 2; EOEE: early-onset epileptic encephalopathy; ER: endoplasmic reticulum; ID: intellectual disability; IDR: intrinsically disordered region; MRI: magnetic resonance imaging; NBIA: neurodegeneration with brain iron accumulation; NCOA4: nuclear receptor coactivator 4; PtdIns3P: phosphatidylinositol-3-phosphate; RLS: Rett-like syndrome; WDR45: WD repeat domain 45; WIPI: WD repeat domain, phosphoinositide interacting.
Topics: Autophagy; Carrier Proteins; Humans; Macroautophagy; Neurodegenerative Diseases; Neurodevelopmental Disorders
PubMed: 33843443
DOI: 10.1080/15548627.2021.1899669 -
Journal of Molecular Biology Jan 2020Selective autophagy relies on soluble or membrane-bound cargo receptors that recognize cargo and bring about autophagosome formation at the cargo. The cargo-bound... (Review)
Review
Selective autophagy relies on soluble or membrane-bound cargo receptors that recognize cargo and bring about autophagosome formation at the cargo. The cargo-bound receptors interact with lipidated ATG8 family proteins anchored in the membrane at the concave side of the forming autophagosome. The interaction is mediated by 15- to 20-amino-acid-long sequence motifs called LC3-interacting region (LIR) motifs that bind to the LIR docking site (LDS) of ATG8 proteins. In this review, we focus on LIR-ATG8 interactions and the soluble mammalian selective autophagy receptors. We discuss the roles of ATG8 family proteins as membrane scaffolds in autophagy and the LIR-LDS interaction and how specificity for binding to GABARAP or LC3 subfamily proteins is achieved. We also discuss atypical LIR-LDS interactions and a novel LIR-independent interaction. Recently, it has become clear that several of the soluble cargo receptors are able to recruit components of the core autophagy apparatus to aid in assembling autophagosome formation at the site of cargo sequestration. A model on phagophore recruitment and expansion on a selective autophagy receptor-coated cargo incorporating the latest findings is presented.
Topics: Animals; Apoptosis Regulatory Proteins; Autophagosomes; Autophagy; Autophagy-Related Protein 8 Family; Humans; Macroautophagy; Microtubule-Associated Proteins; Protein Interaction Domains and Motifs; Protein Interaction Maps
PubMed: 31310766
DOI: 10.1016/j.jmb.2019.07.016 -
Autophagy Dec 2021Macroautophagy/autophagy, an evolutionarily conserved process, plays an important role in the regulation of immune inflammation and nervous system homeostasis. However,...
Macroautophagy/autophagy, an evolutionarily conserved process, plays an important role in the regulation of immune inflammation and nervous system homeostasis. However, the exact role and mechanism of autophagy in pain is still unclear. Here, we showed that impaired autophagy flux mainly occurred in astrocytes during the maintenance of neuropathic pain. No matter the stage of neuropathic pain induction or maintenance, activation of autophagy relieved the level of pain, whereas inhibition of autophagy aggravated pain. Moreover, the levels of neuroinflammation and reactive oxygen species (ROS) were increased or decreased following autophagy inhibition or activation. Further study showed that inhibition of autophagy slowed the induction, but increased the maintenance of neuroinflammatory responses, which could be achieved by promoting the binding of TRAF6 (TNF receptor-associated factor 6) to K63 ubiquitinated protein, and increasing the levels of p-MAPK8/JNK (mitogen-activated protein kinase 8) and nuclear factor of kappa light polypeptide gene enhancer in B cells (NFKB/NF-κB). Impaired autophagy also reduced the protective effect of astrocytes on neurons against ROS stress because of the decrease in the level of glutathione released by astrocytes, which could be improved by activating the NFE2L2/NRF2 (nuclear factor, erythroid derived 2, like 2) pathway. We also demonstrated that simultaneous activation of autophagy and the NFE2L2 pathway further relieved pain, compared to activating autophagy alone. Our study provides an underlying mechanism by which autophagy participates in the regulation of neuropathic pain, and a combination of autophagy and NFE2L2 activation may be a new treatment approach for neuropathic pain. 3-MA: 3-methyladenine; 8-OHdG: 8-hydroxydeoxy-guanosine; ACTB: actin, beta; AMPAR: alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor; ATG: autophagy-related; CAMK2/CaMKII: calcium/calmodulin-dependent protein kinase II; CCL7: chemokine (C-C motif) ligand 7; CGAS: cyclic GMP-AMP synthase; CQ: chloroquine; GABA: gamma-aminobutyrate; GCLC: glutamate-cysteine ligase, catalytic subunit; GFAP: glial fibrillary acidic protein; GSH: glutathione; HMOX1/HO-1: heme oxygenase 1; KEAP1: kelch-like ECH-associated protein 1; MAP1LC3/LC3-II: microtubule-associated protein 1 light chain 3 beta (phosphatidylethanolamine-conjugated form); MAPK: mitogen-activated protein kinase; MAPK1/ERK: mitogen-activated protein kinase 1; MMP2: matrix metallopeptidase 2; MAPK8/JNK: mitogen-activated protein kinase 8; MAPK14/p38: mitogen-activated protein kinase 14; NFE2L2/NRF2: nuclear factor, erythroid derived 2, like 2; NFKB/NF-κB: nuclear factor of kappa light polypeptide gene enhancer in B cells; ROS: reactive oxygen species; SLC12A5: solute carrier family 12, member 5; SNL: spinal nerve ligation; TLR4: toll-like receptor 4; TRAF6: TNF receptor-associated factor; TRP: transient receptor potential.
Topics: Autophagy; Humans; Kelch-Like ECH-Associated Protein 1; Macroautophagy; NF-E2-Related Factor 2; Neuralgia
PubMed: 33834930
DOI: 10.1080/15548627.2021.1900498 -
Science (New York, N.Y.) Apr 2018Endolysosomes can be damaged by diverse materials. Terminally damaged compartments are degraded by lysophagy, but pathways that repair salvageable organelles are poorly...
Endolysosomes can be damaged by diverse materials. Terminally damaged compartments are degraded by lysophagy, but pathways that repair salvageable organelles are poorly understood. Here we found that the endosomal sorting complex required for transport (ESCRT) machinery, known to mediate budding and fission on endolysosomes, also plays an essential role in their repair. ESCRTs were rapidly recruited to acutely injured endolysosomes through a pathway requiring calcium and ESCRT-activating factors that was independent of lysophagy. We used live-cell imaging to demonstrate that ESCRTs responded to small perforations in endolysosomal membranes and enabled compartments to recover from limited damage. Silica crystals that disrupted endolysosomes also triggered ESCRT recruitment. ESCRTs thus provide a defense against endolysosomal damage likely to be relevant in physiological and pathological contexts.
Topics: Calcium-Binding Proteins; Cell Cycle Proteins; Cell Line, Tumor; DNA-Binding Proteins; Endosomal Sorting Complexes Required for Transport; Endosomes; HeLa Cells; Humans; Lysosomes; Transcription Factors
PubMed: 29622626
DOI: 10.1126/science.aar5078 -
Cell Jul 2019Antibacterial autophagy (xenophagy) is an important host defense, but how it is initiated is unclear. Here, we performed a bacterial transposon screen and identified a...
Antibacterial autophagy (xenophagy) is an important host defense, but how it is initiated is unclear. Here, we performed a bacterial transposon screen and identified a T3SS effector SopF that potently blocked Salmonella autophagy. SopF was a general xenophagy inhibitor without affecting canonical autophagy. S. Typhimurium ΔsopF resembled S. flexneri ΔvirAΔicsB with the majority of intracellular bacteria targeted by autophagy, permitting a CRISPR screen that identified host V-ATPase as an essential factor. Upon bacteria-caused vacuolar damage, the V-ATPase recruited ATG16L1 onto bacteria-containing vacuole, which was blocked by SopF. Mammalian ATG16L1 bears a WD40 domain required for interacting with the V-ATPase. Inhibiting autophagy by SopF promoted S. Typhimurium proliferation in vivo. SopF targeted Gln124 of ATP6V0C in the V-ATPase for ADP-ribosylation. Mutation of Gln124 also blocked xenophagy, but not canonical autophagy. Thus, the discovery of SopF reveals the V-ATPase-ATG16L1 axis that critically mediates autophagic recognition of intracellular pathogen.
Topics: ADP-Ribosylation; Autophagy-Related Proteins; Bacterial Proteins; CRISPR-Cas Systems; Gene Editing; HeLa Cells; Humans; Macroautophagy; Microtubule-Associated Proteins; Protein Binding; Salmonella; Type III Secretion Systems; Vacuolar Proton-Translocating ATPases; Virulence Factors
PubMed: 31327526
DOI: 10.1016/j.cell.2019.06.007 -
Autophagy Jan 2022Macroautophagy/autophagy is a highly conserved process in eukaryotic cells. It plays a critical role in cellular homeostasis by delivering cytoplasmic cargos to... (Review)
Review
Macroautophagy/autophagy is a highly conserved process in eukaryotic cells. It plays a critical role in cellular homeostasis by delivering cytoplasmic cargos to lysosomes for selective degradation. OPTN (optineurin), a well-recognized autophagy receptor, has received considerable attention due to its multiple roles in the autophagic process. OPTN is associated with many human disorders that are closely related to autophagy, such as rheumatoid arthritis, osteoporosis, and nephropathy. Here, we review the function of OPTN as an autophagy receptor at different stages of autophagy, focusing on cargo recognition, autophagosome formation, autophagosome maturation, and lysosomal quality control. OPTN tends to be protective in most autophagy associated diseases, though the molecular mechanism of OPTN regulation in these diseases is not well understood. A comprehensive review of the function of OPTN in autophagy provides valuable insight into the pathogenesis of human diseases related to OPTN and facilitates the discovery of potential key regulators and novel therapeutic targets for disease intervention in patients with autophagic diseases.: ATG: autophagy-related; APAP: acetaminophen; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CC: coiled-coil; HACE1: HECT domain and ankyrin repeat containing E3 ubiquitin protein ligase 1; MYO6: myosin VI; IKBKG/NEMO: inhibitor of nuclear factor kappa B kinase regulatory subunit gamma; IKK: IκB kinase; LIR: LC3-interacting region; LZ: leucine zipper; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NFKB/NF-κB: nuclear factor kappa B subunit; OPTN: optineurin; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; PINK1: PTEN induced kinase 1; PRKN: parkin RBR E3 ubiquitin protein ligase; RTECs: renal tubular epithelial cells; SQSTM1/p62: sequestosome 1; TBK1: TANK binding kinase 1; TOM1: target of myb1 membrane trafficking protein; UBD: ubiquitin-binding domain; ULK1: unc-51 like autophagy activating kinase 1; WIPI2: WD repeat domain, phosphoinositide interacting 2; ZF: zinc finger.
Topics: Autophagy; Humans; I-kappa B Kinase; Lysosomes; Macroautophagy; Protein Binding; Ubiquitin-Protein Ligases
PubMed: 33783320
DOI: 10.1080/15548627.2021.1908722 -
Autophagy May 2021The fusion of autophagosomes and endosomes/lysosomes, also called autophagosome maturation, ensures the degradation of autophagic cargoes. It is an important regulatory...
The fusion of autophagosomes and endosomes/lysosomes, also called autophagosome maturation, ensures the degradation of autophagic cargoes. It is an important regulatory step of the macroautophagy/autophagy process. STX17 is the key autophagosomal SNARE protein that mediates autophagosome maturation. Here, we report that the acetylation of STX17 regulates its SNARE activity and autophagic degradation. The histone acetyltransferase CREBBP/CBP and the deacetylase HDAC2 specifically regulate the acetylation of STX17. In response to cell starvation and MTORC1 inhibition, the inactivation of CREBBP leads to the deacetylation of STX17 at its SNARE domain. This deacetylation promotes the interaction between STX17 and SNAP29 and the formation of the STX17-SNAP29-VAMP8 SNARE complex with no effect on the recruitment of STX17 to autophagosomal membranes. Deacetylation of STX17 also enhances the interaction between STX17 and the tethering complex HOPS, thereby further promoting autophagosome-lysosome fusion. Our study suggests a mechanism by which acetylation regulates the late-stage of autophagy, and possibly other STX17-related intracellular membrane fusion events. ACTB: actin beta; CREBBP/CBP: CREB binding protein; Ctrl: control; GFP: green fluorescent protein; GST: glutathione S-transferase; HDAC: histone deacetylase; HOPS: homotypic fusion and protein sorting complex; KO: knockout; LAMP1/2: lysosomal associated membrane protein 1/2; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MEFs: mouse embryonic fibroblasts; MS: mass spectrometry; MTORC1: mechanistic target of rapamycin kinase complex 1; NAM: nicotinamide; PtdIns3K: phosphatidylinositol 3-kinase; RFP: red fluorescent protein; SNAP29: synaptosome associated protein 29; SNARE: soluble N-ethylamide-sensitive factor attachment protein receptor; SQSTM1/p62: sequestosome 1; STX17: syntaxin 17; TSA: trichostatin A; TSC1/2: TSC complex subunit 1/2; VAMP8: vesicle associated membrane protein 8; WT: wild type.
Topics: Autophagosomes; Autophagy; Endosomes; Fibroblasts; Humans; Lysosomes; Macroautophagy; Membrane Fusion; Qa-SNARE Proteins
PubMed: 32264736
DOI: 10.1080/15548627.2020.1752471 -
Autophagy Aug 2021TMEM41B and VMP1, two endoplasmic reticulum (ER)-resident transmembrane proteins, play important roles in regulating the formation of lipid droplets (LDs), autophagy... (Review)
Review
TMEM41B and VMP1, two endoplasmic reticulum (ER)-resident transmembrane proteins, play important roles in regulating the formation of lipid droplets (LDs), autophagy initiation, and viral infection. However, the biochemical functions of TMEM41B and VMP1 are unclear. A lipids distribution screen suggested TMEM41B and VMP1 are critical to the normal distribution of cholesterol and phosphatidylserine. Biochemical analyses unveiled that TMEM41B and VMP1 have scramblase activity. These findings shed light on the mechanism by which TMEM41B and VMP1 regulate LD formation, lipids distribution, macroautophagy, and viral infection.
Topics: Animals; Autophagosomes; Autophagy; Humans; Macroautophagy; Membrane Proteins; Phospholipid Transfer Proteins
PubMed: 34074213
DOI: 10.1080/15548627.2021.1937898 -
Cells Feb 2023Autophagy-the lysosomal degradation of cytoplasm-plays a central role in cellular homeostasis and protects cells from potentially harmful agents that may accumulate in... (Review)
Review
Autophagy-the lysosomal degradation of cytoplasm-plays a central role in cellular homeostasis and protects cells from potentially harmful agents that may accumulate in the cytoplasm, including pathogens, protein aggregates, and dysfunctional organelles. This process is initiated by the formation of a phagophore membrane, which wraps around a portion of cytoplasm or cargo and closes to form a double-membrane autophagosome. Upon the fusion of the autophagosome with a lysosome, the sequestered material is degraded by lysosomal hydrolases in the resulting autolysosome. Several alternative membrane sources of autophagosomes have been proposed, including the plasma membrane, endosomes, mitochondria, endoplasmic reticulum, lipid droplets, hybrid organelles, and de novo synthesis. Here, we review recent progress in our understanding of how the autophagosome is formed and highlight the proposed role of vesicles that contain the lipid scramblase ATG9 as potential seeds for phagophore biogenesis. We also discuss how the phagophore is sealed by the action of the endosomal sorting complex required for transport (ESCRT) proteins.
Topics: Autophagosomes; Macroautophagy; Autophagy; Endosomes; Cell Membrane
PubMed: 36831335
DOI: 10.3390/cells12040668 -
Autophagy Jan 2023Macroautophagy/autophagy is a cellular and energy homeostatic mechanism that contributes to maintain the number of primordial follicles, germ cell survival, and...
Macroautophagy/autophagy is a cellular and energy homeostatic mechanism that contributes to maintain the number of primordial follicles, germ cell survival, and anti-ovarian aging. However, it remains unknown whether autophagy in granulosa cells affects oocyte maturation. Here, we show a clear tendency of reduced autophagy level in human granulosa cells from women of advanced maternal age, implying a potential negative correlation between autophagy levels and oocyte quality. We therefore established a co-culture system and show that either pharmacological inhibition or genetic ablation of autophagy in granulosa cells negatively affect oocyte quality and fertilization ability. Moreover, our metabolomics analysis indicates that the adverse impact of autophagy impairment on oocyte quality is mediated by downregulated citrate levels, while exogenous supplementation of citrate can significantly restore the oocyte maturation. Mechanistically, we found that ACLY (ATP citrate lyase), which is a crucial enzyme catalyzing the cleavage of citrate, was preferentially associated with K63-linked ubiquitin chains and recognized by the autophagy receptor protein SQSTM1/p62 for selective autophagic degradation. In human follicles, the autophagy level in granulosa cells was downregulated with maternal aging, accompanied by decreased citrate in the follicular fluid, implying a potential correlation between citrate metabolism and oocyte quality. We also show that elevated citrate levels in porcine follicular fluid promote oocyte maturation. Collectively, our data reveal that autophagy in granulosa cells is a beneficial mechanism to maintain a certain degree of citrate by selectively targeting ACLY during oocyte maturation. 3-MA: 3-methyladenine; ACLY: ATP citrate lyase; AMA: advanced maternal age; CG: cortical granule; CHX: cycloheximide; CQ: chloroquine; CS: citrate synthase; COCs: cumulus-oocyte-complexes; GCM: granulosa cell monolayer; GV: germinal vesicle; MII: metaphase II stage of meiosis; PB1: first polar body; ROS: reactive oxygen species; shRNA: small hairpin RNA; SQSTM1/p62: sequestosome 1; TCA: tricarboxylic acid; TOMM20/TOM20: translocase of outer mitochondrial membrane 20; UBA: ubiquitin-associated domain; Ub: ubiquitin; WT: wild-type.
Topics: Female; Humans; Animals; Swine; Sequestosome-1 Protein; ATP Citrate (pro-S)-Lyase; Macroautophagy; Citric Acid; Autophagy; Oocytes; Citrates; Acyltransferases; Ubiquitin; Homeostasis
PubMed: 35404187
DOI: 10.1080/15548627.2022.2063005