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1.
Cell Rep ; 42(8): 112898, 2023 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-37516958

RESUMO

The mechanism of long-term depression (LTD), a cellular substrate for learning, memory, and behavioral flexibility, is extensively studied in Schaffer collateral (SC) synapses, with inhibition of autophagy identified as a key factor. SC inputs terminate at basal and proximal apical dendrites, whereas distal apical dendrites receive inputs from the temporoammonic pathway (TAP). Here, we demonstrate that TAP and SC synapses have a shared LTD mechanism reliant on NMDA receptors, caspase-3, and autophagy inhibition. Despite this shared LTD mechanism, proximal apical dendrites contain more autophagosomes than distal apical dendrites. Additionally, unlike SC LTD, which diminishes with age, TAP LTD persists into adulthood. Our previous study shows that the high autophagy in adulthood disallows SC LTD induction. The reduction of autophagosomes from proximal to distal dendrites, combined with distinct LTD inducibility at SC and TAP synapses, suggests a model where the differential distribution of autophagosomes in dendrites gates LTD inducibility at specific circuits.


Assuntos
Autofagossomos , Dendritos , Hipocampo , Depressão Sináptica de Longo Prazo , Sinapses , Dendritos/fisiologia , Sinapses/fisiologia , Autofagossomos/fisiologia , Animais , Camundongos , Receptores de N-Metil-D-Aspartato/metabolismo , Caspase 3/metabolismo , Autofagia , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/fisiologia , Camundongos Endogâmicos C57BL , Hipocampo/citologia , Hipocampo/fisiologia , Proteínas do Tecido Nervoso/metabolismo
2.
Autophagy ; 19(2): 377-378, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36383451

RESUMO

In recent years, an increasing number of studies have started to investigate the roles of ions and ion channels in macroautophagy/autophagy. One finding is that calcium regulates multiple stages of autophagy with lysosomal calcium release being important for autophagosome and lysosome fusion. MCOLN3/TRPML3, as a calcium-permeable channel that is located on both lysosomes and autophagosomes, has been suggested as an autophagy regulator and a candidate to provide the calcium for autophagic fusion, but how this channel is activated remains unclear. In a recent article, Kim et al. demonstrate that MCOLN3 is a PtdIns3P downstream effector, and the activation of its channel function is critical for autophagosome biogenesis.


Assuntos
Autofagossomos , Autofagia , Fosfatos de Fosfatidilinositol , Canais de Potencial de Receptor Transitório , Autofagossomos/metabolismo , Autofagossomos/fisiologia , Autofagia/genética , Autofagia/fisiologia , Cálcio , Canais de Cálcio/metabolismo , Lisossomos , Macroautofagia , Fosfatos de Fosfatidilinositol/metabolismo , Canais de Potencial de Receptor Transitório/metabolismo
3.
PLoS One ; 17(11): e0276823, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36445873

RESUMO

Mutations in ATP13A2 cause Kufor-Rakeb Syndrome (KRS), a juvenile form of Parkinson's Disease (PD). The gene product belongs to a diverse family of ion pumps and mediates polyamine influx from lysosomal lumen. While the biochemical and structural studies highlight its unique mechanics, how PD pathology is linked to ATP13A2 function remains unclear. Here we report that localization of overexpressed TOM20, a mitochondrial outer-membrane protein, is significantly altered upon ATP13A2 expression to partially merge with lysosome. Using Halo-fused version of ATP13A2, ATP13A2 was identified in lysosome and autophagosome. Upon ATP13A2 co-expression, overexpressed TOM20 was found not only in mitochondria but also within ATP13A2-containing autolysosome. This modification of TOM20 localization was inhibited by adding 1-methyl-4-phenylpyridinium (MPP+) and not accompanied with mitophagy induction. We suggest that ATP13A2 may participate in the control of overexpressed proteins targeted to mitochondrial outer-membrane.


Assuntos
Autofagossomos , Lisossomos , Proteínas do Complexo de Importação de Proteína Precursora Mitocondrial , Transtornos Parkinsonianos , ATPases Translocadoras de Prótons , Humanos , Autofagossomos/genética , Autofagossomos/fisiologia , Lisossomos/genética , Lisossomos/fisiologia , Proteínas de Membrana , Mitocôndrias/genética , Mitocôndrias/fisiologia , Membranas Mitocondriais/fisiologia , Mitofagia/genética , Mitofagia/fisiologia , ATPases Translocadoras de Prótons/genética , ATPases Translocadoras de Prótons/fisiologia , Transtornos Parkinsonianos/genética , Transtornos Parkinsonianos/fisiopatologia , Proteínas do Complexo de Importação de Proteína Precursora Mitocondrial/fisiologia
4.
Proc Natl Acad Sci U S A ; 119(30): e2201927119, 2022 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-35858426

RESUMO

Hepatitis B virus (HBV) DNA replication takes place inside the viral core particle and is dependent on autophagy. Here we show that HBV core particles are associated with autophagosomes and phagophores in cells that productively replicate HBV. These autophagic membrane-associated core particles contain almost entirely the hypophosphorylated core protein and are DNA replication competent. As the hyperphosphorylated core protein can be localized to phagophores and the dephosphorylation of the core protein is associated with the packaging of viral pregenomic RNA (pgRNA), these results are in support of the model that phagophores can serve as the sites for the packaging of pgRNA. In contrast, in cells that replicate HBV, the precore protein derivatives, which are related to the core protein, are associated with autophagosomes but not with phagophores via a pathway that is independent of its signal peptide. Interestingly, when the core protein is expressed by itself, it is associated with phagophores but not with autophagosomes. These observations indicate that autophagic membranes are differentially involved in the trafficking of precore and core proteins. HBV induces the fusion of autophagosomes and multivesicular bodies and the silencing of Rab11, a regulator of this fusion, is associated with the reduction of release of mature HBV particles. Our studies thus indicate that autophagic membranes participate in the assembly of HBV nucleocapsids, the trafficking of HBV precore and core proteins, and likely also the egress of HBV particles.


Assuntos
Autofagossomos , Vírus da Hepatite B , Nucleocapsídeo , Empacotamento do Genoma Viral , Replicação Viral , Autofagossomos/fisiologia , DNA Viral/metabolismo , Vírus da Hepatite B/genética , Vírus da Hepatite B/fisiologia , Humanos , Nucleocapsídeo/genética , Nucleocapsídeo/fisiologia , Transporte Proteico , RNA Viral/metabolismo , Replicação Viral/genética
5.
Elife ; 112022 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-34982028

RESUMO

Autophagosomes are double-membrane intracellular vesicles that degrade protein aggregates, intracellular organelles, and other cellular components. During the development of the nematode Caenorhabditis elegans, many somatic and germ cells undergo apoptosis. These cells are engulfed and degraded by their neighboring cells. We discovered a novel role of autophagosomes in facilitating the degradation of apoptotic cells using a real-time imaging technique. Specifically, the double-membrane autophagosomes in engulfing cells are recruited to the surfaces of phagosomes containing apoptotic cells and subsequently fuse to phagosomes, allowing the inner vesicle to enter the phagosomal lumen. Mutants defective in the production of autophagosomes display significant defects in the degradation of apoptotic cells, demonstrating the importance of autophagosomes to this process. The signaling pathway led by the phagocytic receptor CED-1, the adaptor protein CED-6, and the large GTPase dynamin (DYN-1) promotes the recruitment of autophagosomes to phagosomes. Moreover, the subsequent fusion of autophagosomes with phagosomes requires the functions of the small GTPase RAB-7 and the HOPS complex components. Further observations suggest that autophagosomes provide apoptotic cell-degradation activities in addition to and in parallel of lysosomes. Our findings reveal that, unlike the single-membrane, LC3-associated phagocytosis (LAP) vesicles reported for mammalian phagocytes, the canonical double-membrane autophagosomes facilitate the clearance of C. elegans apoptotic cells. These findings add autophagosomes to the collection of intracellular organelles that contribute to phagosome maturation, identify novel crosstalk between the autophagy and phagosome maturation pathways, and discover the upstream signaling molecules that initiate this crosstalk.


Assuntos
Apoptose , Autofagossomos/fisiologia , Caenorhabditis elegans/fisiologia , Animais , Fagossomos/fisiologia
6.
Autophagy ; 17(11): 3273-3274, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34482799

RESUMO

It would be quite convenient if every protein had one distinct function, one distinct role in just a single cellular process. In the field of macroautophagy/autophagy, however, we are increasingly finding that this is not the case; several autophagy proteins have two or more roles within the process of autophagy and many even "moonlight" as functional members of entirely different cellular processes. This is perhaps best exemplified by the Atg8-family proteins. These dynamic proteins have already been reported to serve several functions both within autophagy (membrane tethering, membrane fusion, binding to cargo receptors, binding to autophagy machinery) and beyond (LC3-associated phagocytosis, formation of EDEMosomes, immune signaling) but as Maruyama and colleagues suggest in their recent report, this list of functions may not yet be complete.


Assuntos
Família da Proteína 8 Relacionada à Autofagia/fisiologia , Autofagia/fisiologia , Animais , Autofagossomos/química , Autofagossomos/genética , Autofagossomos/fisiologia , Autofagia/genética , Família da Proteína 8 Relacionada à Autofagia/química , Família da Proteína 8 Relacionada à Autofagia/genética , Sítios de Ligação/genética , Humanos , Modelos Moleculares , Simulação de Acoplamento Molecular , Mutação
7.
Cancer Sci ; 112(10): 3972-3978, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34407274

RESUMO

While starvation-induced autophagy is thought to randomly degrade cellular components, under certain circumstances autophagy selectively recognizes, sequesters, and degrades specific targets via autophagosomes. This process is called selective autophagy, and it contributes to cellular homeostasis by degrading specific soluble proteins, supramolecular complexes, liquid-liquid phase-separated droplets, abnormal or excess organelles, and pathogenic invasive bacteria. This means that autophagy, like the ubiquitin-proteasome system, strictly regulates diverse cellular functions through its selectivity. In this short review, we focus on the mechanism of "selective" autophagy, which is rapidly being elucidated.


Assuntos
Autofagossomos/fisiologia , Autofagia/fisiologia , Família da Proteína 8 Relacionada à Autofagia/metabolismo , Fenômenos Fisiológicos Celulares , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Homeostase/fisiologia , Humanos , Organelas , Fagocitose/fisiologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Ubiquitina/metabolismo , Ubiquitinação
8.
Autophagy ; 17(8): 2043-2045, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34110246

RESUMO

Parkinson disease (PD)-causing mutations in the LRRK2 (leucine rich repeat kinase 2) gene hyperactivate LRRK2 kinase activity. Here, we discuss our recent work linking LRRK2 hyperactivation to defective axonal autophagosome transport in neurons. In three different models, we observed that expression of the most common causative mutation for PD, LRRK2G2019S, disrupts processive autophagosome transport in a kinase-dependent manner. Mechanistically, we found that hyperactive LRRK2 recruits SPAG9/JIP4, a motor adaptor known to bind to LRRK2-phosphorylated RAB proteins, to the autophagosomal membrane. Increased SPAG9/JIP4 levels induce abnormal recruitment and activation of kinesin-1, which we propose results in an unproductive tug-of-war between anterograde and retrograde motors bound to autophagosomes. Disruption of autophagosome transport correlates with defective autophagosome maturation, suggesting that hyperactive LRRK2 may impair efficient degradation of autophagosomal cargo. Our work demonstrates that LRRK2 hyperactivation is sufficient to induce defects in autophagosome transport and maturation, further establishing a role of defective autophagy in the pathogenesis of PD.


Assuntos
Autofagia/fisiologia , Transporte Axonal/fisiologia , Axônios/metabolismo , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Autofagossomos/fisiologia , Humanos
9.
Front Immunol ; 12: 675822, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34122437

RESUMO

We have reported that tumor-derived autophagosomes (DRibbles) were efficient carriers of tumor antigens and DRibbles antigens could be present by DRibbles-activated B cells to stimulate effect and naïve T cells in mice. However, the effect of DRibbles on human B cells remains unclear. Herein, we found that DRibbles can also efficiently induce proliferation and activation of human B cells and lead to the production of chemokines, cytokines and hematopoietic growth factors. We further demonstrated human B cells can effectively phagocytose DRibbles directly and cross-present DRibbles antigens to stimulate antigen-specific memory T cells. Furthermore, we found that membrane-bound high-mobility group B1 (HMGB1) on DRibbles was crucial for inducing human B cells activation. Therefore, these findings provide further evidence to promote the clinical application of B-DRibbles vaccines.


Assuntos
Antígenos de Neoplasias/imunologia , Autofagossomos/fisiologia , Linfócitos B/imunologia , Memória Imunológica , Ativação Linfocitária , Linfócitos T/imunologia , Linhagem Celular Tumoral , Proteína HMGB1/fisiologia , Humanos
10.
EMBO J ; 40(15): e108050, 2021 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-34155657

RESUMO

Selective autophagy mediates specific degradation of unwanted cytoplasmic components to maintain cellular homeostasis. The suppressor of gene silencing 3 (SGS3) and RNA-dependent RNA polymerase 6 (RDR6)-formed bodies (SGS3/RDR6 bodies) are essential for siRNA amplification in planta. However, whether autophagy receptors regulate selective turnover of SGS3/RDR6 bodies is unknown. By analyzing the transcriptomic response to virus infection in Arabidopsis, we identified a virus-induced small peptide 1 (VISP1) composed of 71 amino acids, which harbor a ubiquitin-interacting motif that mediates interaction with autophagy-related protein 8. Overexpression of VISP1 induced selective autophagy and compromised antiviral immunity by inhibiting SGS3/RDR6-dependent viral siRNA amplification, whereas visp1 mutants exhibited opposite effects. Biochemistry assays demonstrate that VISP1 interacted with SGS3 and mediated autophagic degradation of SGS3/RDR6 bodies. Further analyses revealed that overexpression of VISP1, mimicking the sgs3 mutant, impaired biogenesis of endogenous trans-acting siRNAs and up-regulated their targets. Collectively, we propose that VISP1 is a small peptide receptor functioning in the crosstalk between selective autophagy and RNA silencing.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/imunologia , Peptídeos/genética , RNA Polimerase Dependente de RNA/metabolismo , Arabidopsis/metabolismo , Arabidopsis/virologia , Proteínas de Arabidopsis/genética , Autofagossomos/fisiologia , Autofagia/fisiologia , Família da Proteína 8 Relacionada à Autofagia/metabolismo , Regulação da Expressão Gênica de Plantas , Mutação , Peptídeos/metabolismo , Imunidade Vegetal , Plantas Geneticamente Modificadas , RNA Interferente Pequeno , RNA Polimerase Dependente de RNA/genética , Nicotiana/genética
11.
Eur J Histochem ; 65(s1)2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34060734

RESUMO

The interplay between autophagy (ATG) and ubiquitin proteasome (UP) cell-clearing systems was recently evidenced at biochemical and morphological levels, where subunits belonging to both pathways co-localize within a novel organelle named autophagoproteasome (APP). We previously documented that APP occurs at baseline conditions, while it is hindered by neurotoxicant administration. This is bound to the activity of the mechanistic target of rapamycin (mTOR), since APP is stimulated by mTOR inhibition, which in turn, is correlated with cell protection. In this brief report, we provide novel, morphological and biochemical evidence on APP, suggesting the presence of active UP subunits within ATG vacuoles. Although a stream of interpretation considers such a merging as a catabolic pathway to clear inactive UP subunits, our data further indicate that UP-ATG merging may rather provide an empowered catalytic organelle.


Assuntos
Autofagossomos/fisiologia , Autofagossomos/ultraestrutura , Autofagia , Organelas/ultraestrutura , Complexo de Endopeptidases do Proteassoma/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Ubiquitina/metabolismo , Animais , Organelas/fisiologia , Células PC12 , Ratos , Transdução de Sinais
12.
Autophagy ; 17(11): 3725-3739, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-33783314

RESUMO

MOAP1 (modulator of apoptosis 1) is a BAX-binding protein tightly regulated by the ubiquitin-proteasome system. Apoptotic stimuli stabilize MOAP1 protein and facilitate its interaction with BAX to promote apoptosis. Here we show that in contrast to being resistant to apoptotic stimuli, MOAP1-deficient cells are hypersensitive to cell death mediated by starvation rendered by EBSS treatment. MOAP1-deficient cells exhibited impairment in macroautophagy/autophagy signaling induced by EBSS. Mechanistic analysis revealed that MOAP1-deficient cells had no notable defect in the recruitment of the pre-autophagosomal phosphatidylinositol-3-phosphate (PtdIns3P)-binding proteins, ZFYVE1/DFCP1 and WIPI2, nor in the LC3 lipidation mechanism regulated by the ATG12-ATG5-ATG16L1 complex upon EBSS treatment. Interestingly, MOAP1 is required for facilitating efficient closure of phagophore in the EBSS-treated cells. Analysis of LC3-positive membrane structures using Halo-tagged LC3 autophagosome completion assay showed that predominantly unclosed phagophore rather than closed autophagosome was present in the EBSS-treated MOAP1-deficient cells. The autophagy substrate SQSTM1/p62, which is normally contained within the enclosed autophagosome under EBSS condition, was also highly sensitive to degradation by proteinase K in the absence of MOAP1. MOAP1 binds LC3 and the binding is critically dependent on a LC3-interacting region (LIR) motif detected at its N-terminal region. Re-expression of MOAP1, but not its LC3-binding defective mutant, MOAP1-LIR, in the MOAP1-deficient cells, restored EBSS-induced autophagy. Together, these observations suggest that MOAP1 serves a distinct role in facilitating autophagy through interacting with LC3 to promote efficient phagophore closure during starvation.Abbreviations: CQ: Chloroquine; EBSS: Earle's Balanced Salt Solution; GABARAP: Gamma-Amino Butyric Acid Receptor Associated Protein; IF: Immunofluorescence; IP: Immunoprecipitation; LAMP1: Lysosomal-Associated Membrane Protein 1; LIR: LC3-Interacting Region; MAP1LC3/LC3: Microtubule Associated Protein 1 Light Chain 3; MEF: Mouse Embryonic Fibroblast; MOAP1: Modulator of Apoptosis 1; PE: Phosphatidylethanolamine; PtdIns3K: class III PtdIns3K complex I; PtdIns3P: Phosphatidylinositol-3-phosphate; STX17: Syntaxin 17; ULK1: unc-51 like autophagy activating kinase 1.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Autofagossomos/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Animais , Proteínas Reguladoras de Apoptose/fisiologia , Autofagossomos/fisiologia , Imunofluorescência , Células HEK293 , Células HeLa , Humanos , Imunoprecipitação , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Eletrônica de Transmissão , Proteínas Associadas aos Microtúbulos/fisiologia
13.
J Cell Biol ; 220(6)2021 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-33783472

RESUMO

Macroautophagy (hereafter "autophagy") is a lysosomal degradation pathway that is important for learning and memory, suggesting critical roles for autophagy at the neuronal synapse. Little is known, however, about the molecular details of how autophagy is regulated with synaptic activity. Here, we used live-cell confocal microscopy to define the autophagy pathway in primary hippocampal neurons under various paradigms of synaptic activity. We found that synaptic activity regulates the motility of autophagic vacuoles (AVs) in dendrites. Stimulation of synaptic activity dampens AV motility, whereas silencing synaptic activity induces AV motility. Activity-dependent effects on dendritic AV motility are local and reversible. Importantly, these effects are compartment specific, occurring in dendrites and not in axons. Most strikingly, synaptic activity increases the presence of degradative autolysosomes in dendrites and not in axons. On the basis of our findings, we propose a model whereby synaptic activity locally controls AV dynamics and function within dendrites that may regulate the synaptic proteome.


Assuntos
Autofagia , Movimento Celular , Dendritos/fisiologia , Hipocampo/fisiologia , Neurônios/fisiologia , Sinapses/fisiologia , Vacúolos/fisiologia , Animais , Autofagossomos/fisiologia , Axônios/fisiologia , Hipocampo/citologia , Lisossomos/fisiologia , Camundongos , Neurônios/citologia , Ratos , Ratos Sprague-Dawley
14.
Autophagy ; 17(11): 3577-3591, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-33535890

RESUMO

Scavenger receptors are pattern recognition receptors that recognize both foreign and self-ligands, and initiate different mechanisms of cellular activation, often as co-receptors. The function of scavenger receptor CD36 in the immune system has mostly been studied in macrophages but it is also highly expressed by innate type B cells where its function is less explored. Here we report that CD36 is involved in macro-autophagy/autophagy in B cells, and in its absence, the humoral immune response is impaired. We found that CD36-deficient B cells exhibit a significantly reduced plasma cell formation, proliferation, mitochondrial mobilization and oxidative phosphorylation. These changes were accompanied by impaired initiation of autophagy, and we found that CD36 regulated autophagy and colocalized with autophagosome membrane protein MAP1LC3/LC3 (microtubule-associated protein 1 light chain 3). When we investigated T-cell-dependent immune responses, we found that mice with CD36 deficiency, specifically in B cells, exhibited attenuated germinal center responses, class switching, and antibody production as well as autophagosome formation. These findings establish a critical role for CD36 in B cell responses and may also contribute to our understanding of CD36-mediated autophagy in other cells as well as in B cell lymphomas that have been shown to express the receptor.Abbreviations: AICDA/AID: activation-induced cytidine deaminase; ATG5: autophagy related 5; ATP: adenosine triphosphate; BCR: B-cell receptor; CPG: unmethylated cytosine-guanosine; CQ: chloroquine; DC: dendritic cells; FOB: follicular B cells; GC: germinal center; Ig: immunoglobulin; LPS: lipopolysaccharide; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MFI: mean fluorescence intensity; MZB: marginal zone B cells; NP-CGG: 4-hydroxy-3-nitrophenylacetyl-chicken gamma globulin; OCR: oxygen consumption rate; oxLDL: oxidized low-density lipoprotein; PC: plasma cells; Rapa: rapamycin; SQSTM1/p62: sequestosome 1; SRBC: sheep red blood cells; Tfh: follicular helper T cells; TLR: toll-like receptor.


Assuntos
Autofagia , Linfócitos B/fisiologia , Antígenos CD36/fisiologia , Imunidade Humoral , Proteínas Associadas aos Microtúbulos/fisiologia , Animais , Autofagossomos/metabolismo , Autofagossomos/fisiologia , Autofagia/fisiologia , Linfócitos B/imunologia , Linfócitos B/metabolismo , Antígenos CD36/metabolismo , Diferenciação Celular , Proliferação de Células , Humanos , Switching de Imunoglobulina , Camundongos , Proteínas Associadas aos Microtúbulos/metabolismo , Plasmócitos/fisiologia , Linfócitos T/imunologia , Linfócitos T/fisiologia
15.
Autophagy ; 17(11): 3848-3864, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-33618632

RESUMO

In humans, TDRD7 (tudor domain containing 7) mutations lead to a syndrome combining congenital cataracts (CCs) and non-obstructive azoospermia (NOA), characterized by abnormal lens development and spermiogenesis. However, the molecular mechanism underlying TDRD7's functions in eye and testicular development are still largely unknown. Here, we show that the depletion of this gene in mice and humans resulted in the accumulation of autophagosomes and the disruption of macroautophagic/autophagic flux. The disrupted autophagic flux in tdrd7-deficient mouse embryonic fibroblasts (MEFs) was caused by a failure of autophagosome fusion with lysosomes. Furthermore, transcriptome analysis and biochemical assays showed that TDRD7 might directly bind to Tbc1d20 mRNAs and downregulate its expression, which is a key regulator of autophagosome maturation, resulting in the disruption of autophagosome maturation. In addition, we provide evidence to show that TDRD7-mediated autophagosome maturation maintains lens transparency by facilitating the removal of damaged proteins and organelles from lens fiber cells and the biogenesis of acrosome. Altogether, our results showed that TDRD7 plays an essential role in the maturation of autophagosomes and that tdrd7 deletion results in eye defects and testicular abnormalities in mice, implicating disrupted autophagy might be the mechanism that contributes to lens development and spermiogenesis defects in human.Abbreviations: CB: chromatoid bodies; CC: congenital cataract; CTSD: cathepsin D; DMSO: dimethyl sulfoxide; LAMP1: lysosomal-associated membrane protein 1; LECs: lens epithelial cells; MAP1LC3/LC3/Atg8: microtubule-associated protein 1 light chain 3; MEFs: mouse embryonic fibroblasts; NOA: non-obstructive azoospermia; OFZ: organelle-free zone; RG: RNA granules; SQSTM1/p62: sequestosome 1; TBC1D20: TBC1 domain family member 20; TDRD7: tudor domain containing 7; TEM: transmission electron microscopy; WT: wild type.


Assuntos
Autofagossomos/metabolismo , Cristalino/crescimento & desenvolvimento , Ribonucleoproteínas/fisiologia , Espermatogênese , Animais , Autofagossomos/fisiologia , Fibroblastos/metabolismo , Perfilação da Expressão Gênica , Humanos , Lisossomos/metabolismo , Camundongos , Ribonucleoproteínas/metabolismo
16.
Autophagy ; 17(11): 3306-3322, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-33632058

RESUMO

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two clinically distinct classes of neurodegenerative disorders. Yet, they share a range of genetic, cellular, and molecular features. Hexanucleotide repeat expansions (HREs) in the C9orf72 gene and the accumulation of toxic protein aggregates in the nervous systems of the affected individuals are among such common features. Though the mechanisms by which HREs cause toxicity is not clear, the toxic gain of function due to transcribed HRE RNA or dipeptide repeat proteins (DPRs) produced by repeat-associated non-AUG translation together with a reduction in C9orf72 expression are proposed as the contributing factors for disease pathogenesis in ALS and FTD. In addition, several recent studies point toward alterations in protein homeostasis as one of the root causes of the disease pathogenesis. In this review, we discuss the effects of the C9orf72 HRE in the autophagy-lysosome pathway based on various recent findings. We suggest that dysfunction of the autophagy-lysosome pathway synergizes with toxicity from C9orf72 repeat RNA and DPRs to drive disease pathogenesis.Abbreviation: ALP: autophagy-lysosome pathway; ALS: amyotrophic lateral sclerosis; AMPK: AMP-activated protein kinase; ATG: autophagy-related; ASO: antisense oligonucleotide; C9orf72: C9orf72-SMCR8 complex subunit; DENN: differentially expressed in normal and neoplastic cells; DPR: dipeptide repeat protein; EIF2A/eIF2α: eukaryotic translation initiation factor 2A; ER: endoplasmic reticulum; FTD: frontotemporal dementia; GAP: GTPase-activating protein; GEF: guanine nucleotide exchange factor; HRE: hexanucleotide repeat expansion; iPSC: induced pluripotent stem cell; ISR: integrated stress response; M6PR: mannose-6-phosphate receptor, cation dependent; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MN: motor neuron; MTORC1: mechanistic target of rapamycin kinase complex 1; ND: neurodegenerative disorder; RAN: repeat-associated non-ATG; RB1CC1/FIP200: RB1 inducible coiled-coil 1; SLC66A1/PQLC2: solute carrier family 66 member 1; SMCR8: SMCR8-C9orf72 complex subunit; SQSTM1/p62: sequestosome 1; STX17: syntaxin 17; TARDBP/TDP-43: TAR DNA binding protein; TBK1: TANK binding kinase 1; TFEB: transcription factor EB; ULK1: unc-51 like autophagy activating kinase 1; UPS: ubiquitin-proteasome system; WDR41: WD repeat domain 41.


Assuntos
Esclerose Lateral Amiotrófica/genética , Autofagia/genética , Proteína C9orf72/genética , Demência Frontotemporal/genética , Lisossomos/genética , Esclerose Lateral Amiotrófica/patologia , Esclerose Lateral Amiotrófica/fisiopatologia , Animais , Autofagossomos/genética , Autofagossomos/patologia , Autofagossomos/fisiologia , Autofagia/fisiologia , Transporte Axonal/genética , Transporte Axonal/fisiologia , Proteína C9orf72/fisiologia , Expansão das Repetições de DNA/genética , Expansão das Repetições de DNA/fisiologia , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Demência Frontotemporal/patologia , Demência Frontotemporal/fisiopatologia , Terapia Genética , Humanos , Lisossomos/fisiologia , Modelos Neurológicos , Degeneração Neural/genética , Degeneração Neural/patologia , Degeneração Neural/fisiopatologia , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/fisiopatologia , Proteostase/genética , Proteostase/fisiologia , Proteínas de Ligação a RNA/fisiologia
17.
Bull Cancer ; 108(3): 304-322, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33423775

RESUMO

Autophagy refers to the formation of autophagosomes by membrane wrapping part of the cytoplasm and the organelles and proteins that need to be degraded in the cells. Autophagosomes are fused with lysosomes to form autophagolysosome, which degrade the contents of the inclusions, to achieve cell homeostasis and organelle renewal. The regulatory mechanism of autophagy is complex, and its upstream signaling pathway mainly involves mTOR dependent pathway and mTOR independent pathway (AMPK, PI3K, Ras-MAPK, p53, PTEN, endoplasmic reticulum stress). Autophagy is a phenomenon of "self-eating" in cells. Apoptosis is a phenomenon of "self-killing". Both of them share the same stimulating factors and regulatory proteins, but the threshold of induction is different. How to transform and coordinate is not clear at present. This paper summarizes the history of autophagy discovery, the structure and function of related molecules, the biological function of autophagy, the regulatory mechanism and the research results of the relationship between autophagy and apoptosis.


Assuntos
Autofagossomos/fisiologia , Autofagia/fisiologia , Pesquisa Biomédica , Apoptose/fisiologia , Humanos
19.
J Neurochem ; 157(3): 752-763, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33354770

RESUMO

Fused in sarcoma (FUS) is a ubiquitously expressed RNA/DNA-binding protein that plays different roles in the cell. FUS pathology has been reported in neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Mutations in FUS have also been linked to a subset of familial ALS. FUS is mainly localized in the nucleus although it shuttles between the nucleus and the cytoplasm. ALS-linked mutations cause the accumulation of the FUS protein in cytoplasm where it forms stress granule-like inclusions. The protein- and RNA-containing inclusions are reported to be positive of autophagosome markers and degraded by the autophagy pathway. However, the role of FUS in the autophagy pathway remains to be better understood. Using immunoblot and confocal imaging techniques in this study, we found that FUS knockout (KO) cells showed a decreased basal autophagy level. Rapamycin and bafilomycin A1 treatment showed that FUS KO cells were not able to initiate autophagy as efficiently as wild-type cells, suggesting that the autophagosome formation is affected in the absence of FUS. Moreover, using immunoblot and quantitative PCR techniques, we found that the mRNA and protein levels of the genes critical in the initial steps of the autophagy pathway (FIP200, ATG16L1 and ATG12) were significantly lower in FUS KO cells. Re-expressing FUS in the KO cells restored the expression of FIP200 and ATG16L1. Our findings demonstrate a novel role of FUS in the autophagy pathway, that is, regulating the transcription of genes involved in early stages of autophagy such as the initiation and elongation of autophagosomes.


Assuntos
Autofagossomos/genética , Autofagossomos/fisiologia , Autofagia/genética , Autofagia/fisiologia , Proteína FUS de Ligação a RNA/genética , Proteína FUS de Ligação a RNA/fisiologia , Animais , Autofagossomos/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Proteínas Relacionadas à Autofagia/genética , Proteínas Relacionadas à Autofagia/fisiologia , Linhagem Celular , Regulação da Expressão Gênica , Técnicas de Inativação de Genes , Macrolídeos/farmacologia , Camundongos , Complexo de Endopeptidases do Proteassoma , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Transdução de Sinais/genética , Sirolimo/farmacologia
20.
EMBO J ; 40(4): e105120, 2021 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-33368531

RESUMO

Autophagy is a lysosome-dependent degradation pathway essential to maintain cellular homeostasis. Therefore, either defective or excessive autophagy may be detrimental for cells and tissues. The past decade was characterized by significant advances in molecular dissection of stimulatory autophagy inputs; however, our understanding of the mechanisms that restrain autophagy is far from complete. Here, we describe a negative feedback mechanism that limits autophagosome biogenesis based on the selective autophagy-mediated degradation of ATG13, a component of the ULK1 autophagy initiation complex. We demonstrate that the centrosomal protein OFD1 acts as bona fide autophagy receptor for ATG13 via direct interaction with the Atg8/LC3/GABARAP family of proteins. We also show that patients with Oral-Facial-Digital type I syndrome, caused by mutations in the OFD1 gene, display excessive autophagy and that genetic inhibition of autophagy in a mouse model of the disease, significantly ameliorates polycystic kidney, a clinical manifestation of the disorder. Collectively, our data report the discovery of an autophagy self-regulated mechanism and implicate dysregulated autophagy in the pathogenesis of renal cystic disease in mammals.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Autofagossomos/fisiologia , Família da Proteína 8 Relacionada à Autofagia/metabolismo , Autofagia , Proteínas Associadas aos Microtúbulos/metabolismo , Doenças Renais Policísticas/patologia , Proteínas/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Família da Proteína 8 Relacionada à Autofagia/genética , Humanos , Lisossomos/metabolismo , Lisossomos/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Associadas aos Microtúbulos/genética , Doenças Renais Policísticas/etiologia , Doenças Renais Policísticas/metabolismo , Proteínas/genética
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