Making the connection: How membrane contact sites have changed our view of organelle biology

Cell, Journal Year: 2024, Volume and Issue: 187(2), P. 257 - 270

Published: Jan. 1, 2024

The view of organelles and how they operate together has changed dramatically over the last two decades. textbook was that operated largely independently were connected by vesicular trafficking diffusion signals through cytoplasm. We now know all make functional close contacts with one another, often called membrane contact sites. study these sites moved to center stage in cell biology as it become clear play critical roles healthy developing cells during stress disease states. Contact have important intracellular signaling, lipid metabolism, motor-protein-mediated dynamics, organelle division, biogenesis. Here, we summarize major conceptual changes occurred come appreciate integrate activities organelles.

Language: Английский

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The Role of ATG9 Vesicles in Autophagosome Biogenesis

Journal of Molecular Biology, Journal Year: 2024, Volume and Issue: 436(15), P. 168489 - 168489

Published: Feb. 10, 2024

Autophagy mediates the degradation and recycling of cellular material in lysosomal system. Dysfunctional autophagy is associated with a plethora diseases including uncontrolled infections, cancer neurodegeneration. In macroautophagy (hereafter autophagy) this encapsulated double membrane vesicles, autophagosomes, which form upon induction autophagy. The precursors to referred as phagophores, first appear small flattened cisternae, gradually enclose cargo they grow. assembly phagophores during initiation has been major subject investigation over past decades. A special focus ATG9, only conserved transmembrane protein among core machinery. majority ATG9 localizes Golgi-derived vesicles. Here we review recent advances breakthroughs regarding our understanding how vesicles it resides serve assemble machinery establish contact sites for autophagosome biogenesis. We also highlight open questions field that need be addressed years come.

Language: Английский

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ATG9A facilitates the closure of mammalian autophagosomes

The Journal of Cell Biology, Journal Year: 2025, Volume and Issue: 224(2)

Published: Jan. 2, 2025

Canonical autophagy captures within specialized double-membrane organelles, termed autophagosomes, an array of cytoplasmic components destined for lysosomal degradation. An autophagosome is completed when the growing phagophore undergoes ESCRT-dependent membrane closure, a prerequisite its subsequent fusion with endolysosomal organelles and degradation sequestered cargo. ATG9A, key integral protein pathway, best known role in formation expansion phagophores. Here, we report hitherto unappreciated function mammalian ATG9A directing closure. partners IQGAP1 ESCRT-III component CHMP2A to facilitate this final stage formation. Thus, central hub governing all major aspects biogenesis, from unique ATG factor progressive functionalities affecting physiological outputs autophagy.

Language: Английский

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Noncanonical roles of ATG5 and membrane atg8ylation in retromer assembly and function

eLife, Journal Year: 2025, Volume and Issue: 13

Published: Jan. 7, 2025

ATG5 is one of the core autophagy proteins with additional functions such as noncanonical membrane atg8ylation, which among a growing number biological outputs includes control tuberculosis in animal models. Here, we show that associates retromer’s components VPS26, VPS29, and VPS35 modulates retromer function. Knockout blocked trafficking key glucose transporter sorted by retromer, GLUT1, to plasma membrane. Knockouts other genes essential for component, affected GLUT1 sorting, indicating atg8ylation process affects function endosomal sorting. The contribution sorting was independent canonical autophagy. These findings expand scope specific processes cell dependent on its known interactors.

Language: Английский

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In situ snapshots along a mammalian selective autophagy pathway

Proceedings of the National Academy of Sciences, Journal Year: 2023, Volume and Issue: 120(12)

Published: March 14, 2023

Selective macroautophagy (hereafter referred to as autophagy) describes a process in which cytosolic material is engulfed double membrane organelle called an autophagosome. Autophagosomes are carriers responsible for delivering their content lytic compartment destruction. The cargo can be of diverse origin, ranging from macromolecular complexes protein aggregates, organelles, and even invading pathogens. Each unique composition size, presenting different challenges autophagosome biogenesis. Among the largest cargoes targeted by autophagy machinery intracellular bacteria, can, case Salmonella, range 2 5 μm length 0.5 1.5 width. How phagophores form expand on such large remains mechanistically unclear. Here, we used HeLa cells infected with auxotrophic Salmonella study phagophore biogenesis using situ correlative cryo-ET. We show that host generate multiple at site damaged -containing vacuoles (SCVs). observed structures disk-shaped expanded cup-shaped phagophores, have thin intermembrane lumen dilating rim region SCV, outer , or existing templates. Phagophore rims establish forms contact endoplasmic reticulum (ER) via structurally distinct molecular entities formation expansion. Early omegasomes correlated marker Double-FYVE domain-Containing Protein 1 (DFCP1) close association ER without apparent continuity. Our provides insights into around one selective cargoes.

Language: Английский

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Metamorphic proteins at the basis of human autophagy initiation and lipid transfer

Molecular Cell, Journal Year: 2023, Volume and Issue: 83(12), P. 2077 - 2090.e12

Published: May 19, 2023

Autophagy is a conserved intracellular degradation pathway that generates de novo double-membrane autophagosomes to target wide range of material for lysosomal degradation. In multicellular organisms, autophagy initiation requires the timely assembly contact site between ER and nascent autophagosome. Here, we report in vitro reconstitution full-length seven-subunit human supercomplex built on core complex ATG13-101 ATG9. Assembly this rare ability ATG13 ATG101 switch distinct folds. The slow spontaneous metamorphic conversion rate limiting self-assembly supercomplex. interaction with ATG2-WIPI4 enhances tethering membrane vesicles accelerates lipid transfer ATG2 by both ATG9 ATG13-101. Our work uncovers molecular basis its mechanisms imposed metamorphosis regulate autophagosome biogenesis space time.

Language: Английский

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Exploring the ATG9A interactome uncovers interaction with VPS13A

Journal of Cell Science, Journal Year: 2024, Volume and Issue: 137(4)

Published: Jan. 31, 2024

ATG9A, a transmembrane protein of the core autophagy pathway, cycles between Golgi, endosomes and vesicular compartment. ATG9A was recently shown to act as lipid scramblase, this function is thought require its interaction with another protein, ATG2A, which acts transfer protein. Together, ATG2A are proposed expand growing autophagosome. However, implicated in other pathways including membrane repair droplet homeostasis. To elucidate interactors within or beyond autophagy, we performed an interactome analysis through mass spectrometry. This revealed host proteins involved synthesis trafficking, ACSL3, VPS13A VPS13C. Furthermore, show that directly interacts forms complex distinct from ATG9A-ATG2A complex.

Language: Английский

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Molecular Mechanism of Autophagosome–Lysosome Fusion in Mammalian Cells

Cells, Journal Year: 2024, Volume and Issue: 13(6), P. 500 - 500

Published: March 13, 2024

In eukaryotes, targeting intracellular components for lysosomal degradation by autophagy represents a catabolic process that evolutionarily regulates cellular homeostasis. The successful completion of initiates the engulfment cytoplasmic materials within double-membrane autophagosomes and subsequent delivery to autolysosomes acidic proteases. formation relies on precise fusion with lysosomes. recent decades, numerous studies have provided insights into molecular regulation autophagosome–lysosome fusion. this review, an overview molecules function in lysosomes is provided. Moreover, mechanism underlying how these functional regulate summarized.

Language: Английский

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Mechanisms of autophagosome formation

Proceedings of the Japan Academy Series B, Journal Year: 2025, Volume and Issue: 101(1), P. 32 - 40

Published: Jan. 1, 2025

The formation of autophagosomes is a pivotal step in autophagy, lysosomal degradation system that plays crucial role maintaining cellular homeostasis. After autophagy induction, phase separation the autophagy-related (Atg) 1 complex occurs, facilitating gathering Atg proteins and organizes autophagosome site, where initial isolation membrane (IM)/phagophore generated. IM then expands after receiving phospholipids from endomembranes such as endoplasmic reticulum. This process driven by collaboration lipid transfer (Atg2) scrambling (Atg9) proteins. assumes cup shaped morphology undergoes closure, resulting double membrane-bound autophagosome. Atg8 lipidation hypothesized to be factor this process. review presents an overview current understanding these processes discusses basic mechanisms formation.

Language: Английский

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A role for Vps13-mediated lipid transfer at the ER–endosome contact site in ESCRT-mediated sorting

The Journal of Cell Biology, Journal Year: 2024, Volume and Issue: 223(4)

Published: Feb. 6, 2024

Endosomes are specialized organelles that function in the secretory and endocytic protein sorting pathways. Endocytosed cell surface receptors transporters destined for lysosomal degradation sorted into intraluminal vesicles (ILVs) at endosomes by endosomal complexes required transport (ESCRT) proteins. The (multivesicular bodies, MVBs) then fuse with lysosome. During maturation, number of ILVs increases, but size does not decrease despite consumption limiting membrane during ILV formation. Vesicle-mediated trafficking is thought to provide lipids support MVB biogenesis. However, we have uncovered an unexpected contribution a large bridge-like lipid transfer protein, Vps13, this process. Here, reveal Vps13-mediated ER–endosome contact sites ESCRT pathway. We propose Vps13 may play critical role supplying endosome, ensuring continuous ESCRT-mediated

Language: Английский

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