Differential requirement for ATG2A domains for localization to autophagic membranes and lipid droplets

Tamura, Norito; Nishimura, Taki; Sakamaki, Yuriko; Koyama-Honda, Ikuko; Yamamoto, Hayashi; Mizushima, Noboru

doi:10.1002/1873-3468.12901

Cited by 80 publications

(114 citation statements)

References 41 publications

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“…Using confocal imaging and flow cytometry to quantify, tandem-tagged LC3B puncta in ATG2A/2B DKO cells under complete medium (CM) or starvation conditions were both GFP-and mCherry-positive ( Fig 3A and quantified in 3B). This indicated that the ATG2A/B DKO U2OS cells had impaired autophagy flux, consistent with previous work [46]. Stable reconstitution of tandem-LC3B expressing ATG2A/B DKO cells with ATG2A-WT resulted in more mCherryonly-positive cells/puncta in CM conditions that were increased upon starvation and was nullified using bafilomycin A1 (to prevent lysosome acidification and quenching of GFP signal) ( Fig 3A and quantified in 3B).…”

supporting

confidence: 90%

“…The depletion of TRAPC11 results in a phenotype similar to that of ATG2A/B DKO and ATG2A-mLIR [53]. The mammalian ATG2 proteins, ATG2A and ATG2B, have been shown to be essential for phagophore formation and closure [32,33,46], and depletion of WIPI4, a constitutive interaction partner of mammalian ATG2s, also negatively impacts on phagophore closure [29]. Herein, we have described a hitherto unidentified GABARAP/GABARAP-L1 interaction region on both ATG2A and ATG2B that is essential for phagophore formation.…”

Section: Atg2a-lir Is Essential For Autophagosome Formationmentioning

confidence: 99%

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A conserved ATG2‐GABARAP family interaction is critical for phagophore formation

et al. 2020

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The intracellular trafficking pathway, macroautophagy, is a recycling and disposal service that can be upregulated during periods of stress to maintain cellular homeostasis. An essential phase is the elongation and closure of the phagophore to seal and isolate unwanted cargo prior to lysosomal degradation. Human ATG2A and ATG2B proteins, through their interaction with WIPI proteins, are thought to be key players during phagophore elongation and closure, but little mechanistic detail is known about their function. We have identified a highly conserved motif driving the interaction between human ATG2 and GABARAP proteins that is in close proximity to the ATG2‐WIPI4 interaction site. We show that the ATG2A‐GABARAP interaction mutants are unable to form and close phagophores resulting in blocked autophagy, similar to ATG2A/ATG2B double‐knockout cells. In contrast, the ATG2A‐WIPI4 interaction mutant fully restored phagophore formation and autophagy flux, similar to wild‐type ATG2A. Taken together, we provide new mechanistic insights into the requirements for ATG2 function at the phagophore and suggest that an ATG2‐GABARAP/GABARAP‐L1 interaction is essential for phagophore formation, whereas ATG2‐WIPI4 interaction is dispensable.

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confidence: 90%

Section: Atg2a-lir Is Essential For Autophagosome Formationmentioning

confidence: 99%

A conserved ATG2‐GABARAP family interaction is critical for phagophore formation

et al. 2020

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“…Some of the structures in the ATG2‐depleted cells appeared circular in shape. However, because circular structures were not seen in ATG2A/ATG2B double knockout cells, such structures in the depleted cells probably resulted from an incomplete inactivation of the protein. Indeed, only small membranes were seen in the absence of both ATG2 proteins, supporting the notion that ATG2 is required for isolation membrane elongation.…”

Section: Discussionmentioning

confidence: 97%

TRAPPC11 functions in autophagy by recruiting ATG2B‐WIPI4/WDR45 to preautophagosomal membranes

Stanga

Zhao

Milev

et al. 2019

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TRAPPC11 has been implicated in membrane traffic and lipid‐linked oligosaccharide synthesis, and mutations in TRAPPC11 result in neuromuscular and developmental phenotypes. Here, we show that TRAPPC11 has a role upstream of autophagosome formation during macroautophagy. Upon TRAPPC11 depletion, LC3‐positive membranes accumulate prior to, and fail to be cleared during, starvation. A proximity biotinylation assay identified ATG2B and its binding partner WIPI4/WDR45 as TRAPPC11 interactors. TRAPPC11 depletion phenocopies that of ATG2 and WIPI4 and recruitment of both proteins to membranes is defective upon reduction of TRAPPC11. We find that a portion of TRAPPC11 and other TRAPP III proteins localize to isolation membranes. Fibroblasts from a patient with TRAPPC11 mutations failed to recruit ATG2B‐WIPI4, suggesting that this interaction is physiologically relevant. Since ATG2B‐WIPI4 is required for isolation membrane expansion, our study suggests that TRAPPC11 plays a role in this process. We propose a model whereby the TRAPP III complex participates in the formation and expansion of the isolation membrane at several steps.

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“…Both binding regions were shown to be important for autophagy . Furthermore, the existence of two membrane‐binding regions in ATG2A was suggested by truncational analysis in vivo . The IM edge and ERES assume a high curvature and PI3P is enriched in the IM .…”

Section: Establishment Of the Membrane‐tethering Activity Of Atg2mentioning

confidence: 99%

“…37 Furthermore, the existence of two membrane-binding regions in ATG2A was suggested by truncational analysis in vivo. 38 The IM edge and ERES assume a high curvature 39 and PI3P is enriched in the IM. 40 Moreover, the N-terminal portion of Atg2 was shown to be sufficient for targeting green fluorescent protein to the ER.…”

Section: Osawa and Nodamentioning

confidence: 99%

Atg2: A novel phospholipid transfer protein that mediates de novo autophagosome biogenesis

Osawa

Noda

2019

Protein Science

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The degradation of cytoplasmic components via autophagy is crucial for intracellular homeostasis. In the process of autophagy, a newly synthesized isolation membrane (IM) is developed to sequester degradation targets and eventually the IM seals, forming an autophagosome. One of the most poorly understood autophagy‐related proteins is Atg2, which is known to localize to a contact site between the edge of the expanding IM and the exit site of the endoplasmic reticulum (ERES). Recent advances in structural and biochemical analyses have been applied to Atg2 and have revealed it to be a novel multifunctional protein that tethers membranes and transfers phospholipids between them. Considering that Atg2 is essential for the expansion of the IM that requires phospholipids as building blocks, it is suggested that Atg2 transfers phospholipids from the ERES to the IM during the process of autophagosome formation, suggesting that lipid transfer proteins can mediate de novo organelle biogenesis.

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Differential requirement for ATG2A domains for localization to autophagic membranes and lipid droplets

Cited by 80 publications

References 41 publications

A conserved ATG2‐GABARAP family interaction is critical for phagophore formation

A conserved ATG2‐GABARAP family interaction is critical for phagophore formation

TRAPPC11 functions in autophagy by recruiting ATG2B‐WIPI4/WDR45 to preautophagosomal membranes

Atg2: A novel phospholipid transfer protein that mediates de novo autophagosome biogenesis

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