ATG9A and ATG2A form a heteromeric complex essential for autophagosome formation

Molecular Cell, Год журнала: 2022, Номер 82(22), С. 4324 - 4339.e8

Опубликована: Ноя. 1, 2022

ATG9A and ATG2A are essential core members of the autophagy machinery. is a lipid scramblase that allows equilibration lipids across membrane bilayer, whereas facilitates flow between tethered membranes. Although both have been functionally linked during formation autophagosomes, molecular details consequences their interaction remain unclear. By combining data from peptide arrays, crosslinking, hydrogen-deuterium exchange mass spectrometry together with cryoelectron microscopy, we propose model ATG9A-2A complex. Using this integrative structure modeling approach, identify several interfaces mediating would allow direct transfer into lipid-binding perpendicular branch ATG9A. Mutational analyses combined functional activity assays demonstrate importance for autophagy, thereby shedding light on protein complex at heart autophagy.

Язык: Английский

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ATG9 vesicles comprise the seed membrane of mammalian autophagosomes

The Journal of Cell Biology, Год журнала: 2023, Номер 222(7)

Опубликована: Апрель 28, 2023

As the autophagosome forms, its membrane surface area expands rapidly, while volume is kept low. Protein-mediated transfer of lipids from another organelle to likely drives this expansion, but as these are only introduced into cytoplasmic-facing leaflet organelle, full growth also requires lipid scramblase activity. ATG9 harbors activity and essential formation; however, whether integrated mammalian autophagosomes remains unclear. Here we show that in absence transport, vesicles already competent collect proteins found on mature autophagosomes, including LC3-II. Further, use styrene-maleic acid particles reveal nanoscale organization protein LC3-II membranes; each fully expanding autophagosomes. The ratios two at different stages maturation demonstrate not continuously integrated, rather present seed become diluted membrane.

Язык: Английский

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RBG Motif Bridge-Like Lipid Transport Proteins: Structure, Functions, and Open Questions

Annual Review of Cell and Developmental Biology, Год журнала: 2023, Номер 39(1), С. 409 - 434

Опубликована: Июль 5, 2023

The life of eukaryotic cells requires the transport lipids between membranes, which are separated by aqueous environment cytosol. Vesicle-mediated traffic along secretory and endocytic pathways lipid transfer proteins (LTPs) cooperate in this transport. Until recently, known LTPs were shown to carry one or a few at time thought mediate shuttle-like mechanisms. Over last years, new family has been discovered that is defined repeating β-groove (RBG) rod-like structure with hydrophobic channel running their entire length. This localization these membrane contact sites suggest bridge-like mechanism Mutations some result neurodegenerative developmental disorders. Here we review properties well-established putative physiological roles proteins, highlight many questions remain open about functions.

Язык: Английский

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A partnership between the lipid scramblase XK and the lipid transfer protein VPS13A at the plasma membrane

Proceedings of the National Academy of Sciences, Год журнала: 2022, Номер 119(35)

Опубликована: Авг. 22, 2022

Chorea-acanthocytosis (ChAc) and McLeod syndrome are diseases with shared clinical manifestations caused by mutations in VPS13A XK, respectively. Key features of these conditions the degeneration caudate neurons presence abnormally shaped erythrocytes. XK belongs to a family plasma membrane (PM) lipid scramblases whose action results exposure PtdSer at cell surface. is an endoplasmic reticulum (ER)-anchored transfer protein putative role transport lipids contacts ER other membranes. Recently were reported interact still unknown mechanisms. So far, however, there no evidence for colocalization two proteins PM, where resides, as was shown be localized between either mitochondria or droplets. Here we show that can also localize ER–PM via binding its PH domain cytosolic loop such interaction regulated intramolecular within both highly expressed neurons. Binding competitive intracellular membranes mediate tethering functions VPS13A. Our findings support model according which VPS13A-dependent PM coupled scrambling PM. They raise possibility defective surface may responsible neurodegeneration.

Язык: Английский

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Autophagosome Biogenesis

Cells, Год журнала: 2023, Номер 12(4), С. 668 - 668

Опубликована: Фев. 20, 2023

Autophagy–the lysosomal degradation of cytoplasm–plays a central role in cellular homeostasis and protects cells from potentially harmful agents that may accumulate the cytoplasm, including pathogens, protein aggregates, dysfunctional organelles. This process is initiated by formation phagophore membrane, which wraps around portion cytoplasm or cargo closes to form double-membrane autophagosome. Upon fusion autophagosome with lysosome, sequestered material degraded hydrolases resulting autolysosome. Several alternative membrane sources autophagosomes have been proposed, plasma endosomes, mitochondria, endoplasmic reticulum, lipid droplets, hybrid organelles, de novo synthesis. Here, we review recent progress our understanding how formed highlight proposed vesicles contain scramblase ATG9 as potential seeds for biogenesis. We also discuss sealed action endosomal sorting complex required transport (ESCRT) proteins.

Язык: Английский

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Parallel phospholipid transfer by Vps13 and Atg2 determines autophagosome biogenesis dynamics

The Journal of Cell Biology, Год журнала: 2023, Номер 222(7)

Опубликована: Апрель 28, 2023

During autophagy, rapid membrane assembly expands small phagophores into large double-membrane autophagosomes. Theoretical modeling predicts that the majority of autophagosomal phospholipids are derived from highly efficient non-vesicular phospholipid transfer (PLT) across phagophore-ER contacts (PERCS). Currently, tether Atg2 is only PLT protein known to drive phagophore expansion in vivo. Here, our quantitative live-cell imaging analysis reveals a poor correlation between duration and size forming autophagosomes number molecules at PERCS starving yeast cells. Strikingly, we find Atg2-mediated non-rate limiting for autophagosome biogenesis because Vps13 localizes rim promotes parallel with Atg2. In absence Vps13, determines an apparent vivo rate ∼200 per molecule second. We propose conserved proteins cooperate channeling organelle contact sites non-rate-limiting during biogenesis.

Язык: Английский

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

Molecular Cell, Год журнала: 2023, Номер 83(12), С. 2077 - 2090.e12

Опубликована: Май 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.

Язык: Английский

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Lysosome damage triggers acute formation of ER to lysosomes membrane tethers mediated by the bridge-like lipid transport protein VPS13C

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Июнь 8, 2024

Based on genetic studies, lysosome dysfunction is thought to play a pathogenetic role in Parkinson's disease (PD). Here we show that VPS13C, bridge-like lipid transport protein and PD gene, sensor of stress/damage. Upon membrane perturbation, VPS13C rapidly relocates from the cytosol surface lysosomes where it tethers their membranes ER. This recruitment depends Rab7 requires signal at damaged releases an inhibited state which hinders access its VAB domain lysosome-bound Rab7. While another protein, LRRK2, also recruited stressed/damaged lysosomes, occurs much later stages by different mechanisms. Given VPS13 proteins bulk transport, these findings suggest delivery part early protective response damage.

Язык: Английский

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Lipid scrambling is a general feature of protein insertases

Proceedings of the National Academy of Sciences, Год журнала: 2024, Номер 121(17)

Опубликована: Апрель 15, 2024

Glycerophospholipids are synthesized primarily in the cytosolic leaflet of endoplasmic reticulum (ER) membrane and must be equilibrated between bilayer leaflets to allow ER membranes derived from it grow. Lipid equilibration is facilitated by integral proteins called “scramblases.” These feature a hydrophilic groove allowing polar heads lipids traverse hydrophobic interior, similar credit card moving through reader. Nevertheless, despite their fundamental role expansion dynamics, identity most scramblases has remained elusive. Here, combining biochemical reconstitution molecular dynamics simulations, we show that lipid scrambling general protein insertases, which insert polypeptide chains into organelles disconnected vesicle trafficking. Our data indicate occurs same channel insertion takes place abolished presence nascent chains. We propose insertases could have so-far-overlooked as scramblases.

Язык: Английский

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Genetics in Parkinson’s disease, state-of-the-art and future perspectives

British Medical Bulletin, Год журнала: 2024, Номер 149(1), С. 60 - 71

Опубликована: Янв. 27, 2024

Abstract Background Parkinson’s disease (PD) is the second most common neurodegenerative disorder and clinically characterized by presence of motor (bradykinesia, rigidity, rest tremor postural instability) non-motor symptoms (cognitive impairment, autonomic dysfunction, sleep disorders, depression hyposmia). The aetiology PD unknown except for a small but significant contribution monogenic forms. Sources data No new were generated or analyzed in support this review. Areas agreement Up to 15% patients carry pathogenic variants PD-associated genes. Some these genes are associated with mendelian inheritance, while others act as risk factors. Genetic background influences age onset, course, prognosis therapeutic response. controversy testing not routinely offered clinical setting, it may have relevant implications, especially terms prognosis, response therapies inclusion trials. Widely adopted guidelines on genetic still lacking open debate. associations awaiting confirmation, selecting appropriate be included diagnostic panels represents difficult task. Finally, under study whether (and which degree) specific forms influence outcome therapies. Growing points Polygenic Risk Scores (PRS) represent useful tool genetically stratify population risk, outcomes. timely developing research application PRS integrated multi-omics promises improve personalized care patients.

Язык: Английский

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