Modeling Membrane Morphological Change during Autophagosome Formation

Sakai, Yuji; Koyama-Honda, Ikuko; Tachikawa, Masashi; Knorr, Roland L.; Mizushima, Noboru

doi:10.1016/j.isci.2020.101466

Cited by 29 publications

(74 citation statements)

References 40 publications

(85 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The highly bent rim of these cups is covered by a dense coat of ATG16L1, suggesting that ATG16L1 stabilizes highly curved membranes. This observation is consistent with a recent mathematical model predicting that phagophore rims need to be stabilized by a protein coat to prevent their premature collapse 37 . This model also predicted that subunits of this rim-coat partitions to the outer face of phagophores during phagophore expansion and rim constriction, which would explain why ATG16L1 is only present at the outer face of phagophores.…”

Section: Discussionsupporting

confidence: 92%

“…Based on our observations and on predictions from mathematical modelling of phagophore formation 37 , we propose that autophagy starts with the assembly of a circular ATG16L1 coat that buckles the membrane into a highly bent rim (inset 1 and 2 in Extended Data Figure 8b, Figure 4d and Supplementary Movie 12). Removal of ATG16L1 subunits from the rim coat leads to a constriction of these rings which deforms membranes into cups.…”

Section: Discussionmentioning

confidence: 62%

See 1 more Smart Citation

Phagophore formation by the autophagy conjugation machinery

Wollert

Mohan

Blanc

et al. 2022

Preprint

View full text Add to dashboard Cite

Autophagy is a fundamental cellular recycling pathway that captures cytoplasmic material by a phagophore membrane and delivers it to lysosomes for degradation. Nonselective phagophores are generated at specialized ER-domains termed omegasomes. Mechanistically, this process is not well understood. Here, we reconstituted the formation of phagophores from purified components on supported lipid bilayers and by ectopic induction of nonselective autophagy at the plasma membrane. We found that enzymatic conjugation of LC3B to model membranes induces the formation of phagophore-like membrane cups. LC3B functions as membrane anchor, ensuring a sustained interaction of the E3-like ligase complex ATG12¬–ATG5-ATG16L1 with membranes by forming extended membrane coats. ATG16L1 is the major membrane remodeling factor that induces positive membrane curvature, promotes cup formation and stabilizes the rim of membrane cups. Redirecting WIPI2 to the plasma membrane by expressing WIPI2-CAAX induced the formation of omegasome-like membrane cisternae to which LC3B was conjugated. Membrane cups, identical to those observed in vitro, emerged from these cisternae. ATG16L1 variants that did not induce the formation of cups in vitro also failed to promote cup formation in vivo and inhibited the biogenesis of nonselective autophagosomes in cells. We thus propose that ATG16L1 drives the formation of nonselective phagophores by shaping flat donor membranes into membrane cups.

show abstract

Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 62%

Phagophore formation by the autophagy conjugation machinery

Wollert

Mohan

Blanc

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…There are two main hypotheses linked to this concept [ 6 , 94 ]. One is that the highly curved edge of the phagophore is stabilized by membrane-binding proteins that are asymmetrically distributed on the inner and outer membrane of the phagophore [ 94 , 95 ]. The lipidated Atg8/LC3 proteins on the phagophore membrane could be an edge-stabilizing candidate and in line with this notion, it is known that their amount correlates with the size of autophagosomes [ 75 , 96 , 97 ].…”

Section: Autophagosome Formation Mechanismmentioning

confidence: 99%

Molecular regulation of autophagosome formation

Reggiori

2022

Biochemical Society Transactions

View full text Add to dashboard Cite

Macroautophagy, hereafter autophagy, is a degradative process conserved among eukaryotes, which is essential to maintain cellular homeostasis. Defects in autophagy lead to numerous human diseases, including various types of cancer and neurodegenerative disorders. The hallmark of autophagy is the de novo formation of autophagosomes, which are double-membrane vesicles that sequester and deliver cytoplasmic materials to lysosomes/vacuoles for degradation. The mechanism of autophagosome biogenesis entered a molecular era with the identification of autophagy-related (ATG) proteins. Although there are many unanswered questions and aspects that have raised some controversies, enormous advances have been done in our understanding of the process of autophagy in recent years. In this review, we describe the current knowledge about the molecular regulation of autophagosome formation, with a particular focus on budding yeast and mammalian cells.

show abstract

“…After initiation, further membrane curvature is generated. Although the protein identities for this role have not been revealed in mammals [190], in yeast, the sorting nexin Atg20-Atg24 (Snx4) heterodimer, which is known to be on the PAS [191] and is downstream of Vps34 [192], can cause membrane tubulation [193]. Also, a lipidated form of the yeast Atg8 was recently found to have a membrane deformation role [194] (Figure 6).…”

Section: Physicochemical Properties Of Autophagosomal Membranesmentioning

confidence: 99%

Activation Mechanisms of the VPS34 Complexes

Ohashi

2021

Cells

View full text Add to dashboard Cite

Phosphatidylinositol-3-phosphate (PtdIns(3)P) is essential for cell survival, and its intracellular synthesis is spatially and temporally regulated. It has major roles in two distinctive cellular pathways, namely, the autophagy and endocytic pathways. PtdIns(3)P is synthesized from phosphatidylinositol (PtdIns) by PIK3C3C/VPS34 in mammals or Vps34 in yeast. Pathway-specific VPS34/Vps34 activity is the consequence of the enzyme being incorporated into two mutually exclusive complexes: complex I for autophagy, composed of VPS34/Vps34–Vps15/Vps15-Beclin 1/Vps30-ATG14L/Atg14 (mammals/yeast), and complex II for endocytic pathways, in which ATG14L/Atg14 is replaced with UVRAG/Vps38 (mammals/yeast). Because of its involvement in autophagy, defects in which are closely associated with human diseases such as cancer and neurodegenerative diseases, developing highly selective drugs that target specific VPS34/Vps34 complexes is an essential goal in the autophagy field. Recent studies on the activation mechanisms of VPS34/Vps34 complexes have revealed that a variety of factors, including conformational changes, lipid physicochemical parameters, upstream regulators, and downstream effectors, greatly influence the activity of these complexes. This review summarizes and highlights each of these influences as well as clarifying key questions remaining in the field and outlining future perspectives.

show abstract

Modeling Membrane Morphological Change during Autophagosome Formation

Cited by 29 publications

References 40 publications

Phagophore formation by the autophagy conjugation machinery

Phagophore formation by the autophagy conjugation machinery

Molecular regulation of autophagosome formation

Activation Mechanisms of the VPS34 Complexes

Contact Info

Product

Resources

About