Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Filtrar
1.
EMBO Rep ; 24(12): e57300, 2023 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-37987447

RESUMEN

Lysosomes are degradative organelles and signaling hubs that maintain cell and tissue homeostasis, and lysosomal dysfunction is implicated in aging and reduced longevity. Lysosomes are frequently damaged, but their repair mechanisms remain unclear. Here, we demonstrate that damaged lysosomal membranes are repaired by microautophagy (a process termed "microlysophagy") and identify key regulators of the first and last steps. We reveal the AGC kinase STK38 as a novel microlysophagy regulator. Through phosphorylation of the scaffold protein DOK1, STK38 is specifically required for the lysosomal recruitment of the AAA+ ATPase VPS4, which terminates microlysophagy by promoting the disassembly of ESCRT components. By contrast, microlysophagy initiation involves non-canonical lipidation of ATG8s, especially the GABARAP subfamily, which is required for ESCRT assembly through interaction with ALIX. Depletion of STK38 and GABARAPs accelerates DNA damage-induced cellular senescence in human cells and curtails lifespan in C. elegans, respectively. Thus, microlysophagy is regulated by STK38 and GABARAPs and could be essential for maintaining lysosomal integrity and preventing aging.


Asunto(s)
Caenorhabditis elegans , Microautofagia , Animales , Humanos , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Lisosomas/metabolismo , Membranas Intracelulares/metabolismo , Complejos de Clasificación Endosomal Requeridos para el Transporte/genética , Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Autofagia , Proteínas Asociadas a Microtúbulos/metabolismo , Proteínas Reguladoras de la Apoptosis/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo
2.
EMBO Rep ; 24(5): e56134, 2023 05 04.
Artículo en Inglés | MEDLINE | ID: mdl-36929574

RESUMEN

Multisubunit Tethering Complexes (MTCs) are a set of conserved protein complexes that tether vesicles at the acceptor membrane. Interactions with other components of the trafficking machinery regulate MTCs through mechanisms that are partially understood. Here, we systematically investigate the interactome that regulates MTCs. We report that P4-ATPases, a family of lipid flippases, interact with MTCs that participate in the anterograde and retrograde transport at the Golgi, such as TRAPPIII. We use the P4-ATPase Drs2 as a paradigm to investigate the mechanism and biological relevance of this interplay during transport of Atg9 vesicles. Binding of Trs85, the sole-specific subunit of TRAPPIII, to the N-terminal tail of Drs2 stabilizes TRAPPIII on membranes loaded with Atg9 and is required for Atg9 delivery during selective autophagy, a role that is independent of P4-ATPase canonical functions. This mechanism requires a conserved I(S/R)TTK motif that also mediates the interaction of the P4-ATPases Dnf1 and Dnf2 with MTCs, suggesting a broader role of P4-ATPases in MTC regulation.


Asunto(s)
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Adenosina Trifosfatasas/genética , Adenosina Trifosfatasas/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas Relacionadas con la Autofagia/genética , Proteínas Relacionadas con la Autofagia/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , ATPasas Transportadoras de Calcio/química , ATPasas Transportadoras de Calcio/metabolismo , Transportadoras de Casetes de Unión a ATP/metabolismo
3.
EMBO J ; 35(17): 1853-67, 2016 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-27340123

RESUMEN

Autophagy is a multistep membrane traffic pathway. In contrast to autophagosome formation, the mechanisms underlying autophagosome-lysosome fusion remain largely unknown. Here, we describe a novel autophagy regulator, inositol polyphosphate-5-phosphatase E (INPP5E), involved in autophagosome-lysosome fusion process. In neuronal cells, INPP5E knockdown strongly inhibited autophagy by impairing the fusion step. A fraction of INPP5E is localized to lysosomes, and its membrane anchoring and enzymatic activity are necessary for autophagy. INPP5E decreases lysosomal phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2), one of the substrates of the phosphatase, that counteracts cortactin-mediated actin filament stabilization on lysosomes. Lysosomes require actin filaments on their surface for fusing with autophagosomes. INPP5E is one of the genes responsible for Joubert syndrome, a rare brain abnormality, and mutations found in patients with this disease caused defects in autophagy. Taken together, our data reveal a novel role of phosphoinositide on lysosomes and an association between autophagy and neuronal disease.


Asunto(s)
Autofagosomas/metabolismo , Lisosomas/metabolismo , Fusión de Membrana , Neuronas/fisiología , Monoéster Fosfórico Hidrolasas/metabolismo , Anomalías Múltiples/patología , Cerebelo/anomalías , Cerebelo/patología , Anomalías del Ojo/patología , Humanos , Enfermedades Renales Quísticas/patología , Retina/anomalías , Retina/patología
4.
Nature ; 495(7441): 389-93, 2013 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-23455425

RESUMEN

Autophagy is a tightly regulated intracellular bulk degradation/recycling system that has fundamental roles in cellular homeostasis. Autophagy is initiated by isolation membranes, which form and elongate as they engulf portions of the cytoplasm and organelles. Eventually isolation membranes close to form double membrane-bound autophagosomes and fuse with lysosomes to degrade their contents. The physiological role of autophagy has been determined since its discovery, but the origin of autophagosomal membranes has remained unclear. At present, there is much controversy about the organelle from which the membranes originate--the endoplasmic reticulum (ER), mitochondria and plasma membrane. Here we show that autophagosomes form at the ER-mitochondria contact site in mammalian cells. Imaging data reveal that the pre-autophagosome/autophagosome marker ATG14 (also known as ATG14L) relocalizes to the ER-mitochondria contact site after starvation, and the autophagosome-formation marker ATG5 also localizes at the site until formation is complete. Subcellular fractionation showed that ATG14 co-fractionates in the mitochondria-associated ER membrane fraction under starvation conditions. Disruption of the ER-mitochondria contact site prevents the formation of ATG14 puncta. The ER-resident SNARE protein syntaxin 17 (STX17) binds ATG14 and recruits it to the ER-mitochondria contact site. These results provide new insight into organelle biogenesis by demonstrating that the ER-mitochondria contact site is important in autophagosome formation.


Asunto(s)
Autofagia , Retículo Endoplásmico/metabolismo , Membranas Intracelulares/metabolismo , Mitocondrias/metabolismo , Fagosomas/metabolismo , Proteínas Adaptadoras del Transporte Vesicular/metabolismo , Animales , Proteínas Relacionadas con la Autofagia , Células COS , Chlorocebus aethiops , Retículo Endoplásmico/ultraestructura , Técnicas de Silenciamiento del Gen , Células HEK293 , Células HeLa , Humanos , Mitocondrias/ultraestructura , Fagosomas/ultraestructura , Transporte de Proteínas , Proteínas Qa-SNARE/genética , Proteínas Qa-SNARE/metabolismo
5.
J Cell Biol ; 215(5): 649-665, 2016 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-27903607

RESUMEN

Mitophagy is thought to play an important role in mitochondrial quality control. Mitochondrial division is believed to occur first, and autophagosome formation subsequently occurs to enwrap mitochondria as a process of mitophagy. However, there has not been any temporal analysis of mitochondrial division and autophagosome formation in mitophagy. Therefore, the relationships among these processes remain unclear. We show that the mitochondrial division factor Dnm1 in yeast or Drp1 in mammalian cells is dispensable for mitophagy. Autophagosome formation factors, such as FIP200, ATG14, and WIPIs, were essential for the mitochondrial division for mitophagy. Live-cell imaging showed that isolation membranes formed on the mitochondria. A small portion of the mitochondria then divided from parental mitochondria simultaneously with the extension of isolation membranes and autophagosome formation. These findings suggest the presence of a mitophagy process in which mitochondrial division for mitophagy is accomplished together with autophagosome formation.


Asunto(s)
Autofagosomas/metabolismo , GTP Fosfohidrolasas/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismo , Proteínas Mitocondriales/metabolismo , Mitofagia , Animales , Autofagosomas/efectos de los fármacos , Autofagosomas/ultraestructura , Deferiprona , Dinaminas , Células HeLa , Humanos , Mamíferos/metabolismo , Membranas Mitocondriales/efectos de los fármacos , Membranas Mitocondriales/metabolismo , Mitofagia/efectos de los fármacos , Modelos Biológicos , Piridonas/farmacología , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/ultraestructura , Proteínas de Saccharomyces cerevisiae/metabolismo , Imagen de Lapso de Tiempo
6.
Nat Commun ; 1: 142, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-21266992

RESUMEN

Although macroautophagy is known to be an essential degradative process whereby autophagosomes mediate the engulfment and delivery of cytoplasmic components into lysosomes, the lipid changes underlying autophagosomal membrane dynamics are undetermined. Here, we show that phospholipase D1 (PLD1), which is primarily associated with the endosomal system, partially relocalizes to the outer membrane of autophagosome-like structures upon nutrient starvation. The localization of PLD1, as well as the starvation-induced increase in PLD activity, are altered by wortmannin, a phosphatidylinositol 3-kinase inhibitor, suggesting PLD1 may act downstream of Vps34. Pharmacological inhibition of PLD and genetic ablation of PLD1 in mouse cells decreased the starvation-induced expansion of LC3-positive compartments, consistent with a role of PLD1 in the regulation of autophagy. Furthermore, inhibition of PLD results in higher levels of Tau and p62 aggregates in organotypic brain slices. Our in vitro and in vivo findings establish a role for PLD1 in autophagy.


Asunto(s)
Autofagia/fisiología , Fosfolipasa D/metabolismo , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Androstadienos/farmacología , Animales , Autofagia/efectos de los fármacos , Autofagia/genética , Western Blotting , Células CHO , Fosfatidilinositol 3-Quinasas Clase III/antagonistas & inhibidores , Fosfatidilinositol 3-Quinasas Clase III/metabolismo , Cricetinae , Cricetulus , Técnica del Anticuerpo Fluorescente , Células HeLa , Humanos , Ratones , Ratones Noqueados , Microscopía Confocal , Microscopía Electrónica , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Fosfolipasa D/genética , Proteína Sequestosoma-1 , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Wortmanina , Proteínas tau/metabolismo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA