Local Fatty Acid Channeling into Phospholipid Synthesis Drives Phagophore Expansion during Autophagy

Schütter, Maximilian; Giavalisco, Patrick; Brodesser, Susanne; Graef, Martin

doi:10.1016/j.cell.2019.12.005

Cited by 176 publications

(202 citation statements)

References 123 publications

(143 reference statements)

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“…This effect cannot be explained by preferential membrane binding by the E3 complex (Dudley et al, 2019;Lystad et al, 2019), as PO and DO lipids are bound equally (Figure S1G, H). These data, which are consistent with a high proportion of unsaturated lipids in autophagosomal membranes (Schütter et al, 2020), suggest that the presence of two rather than one unsaturated tail in the lipids of the membrane substrates increases the flexibility of the membrane, facilitating structural rearrangements necessary for LC3 lipidation.…”

Section: Reconstitution Of Pi(3)p-and Wipi-dependent Lc3 Lipidationsupporting

confidence: 75%

A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy

Fracchiolla

Chang

Hurley

et al. 2019

Preprint

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Autophagy requires the synthesis of PI(3)P and the conjugation of LC3 to the phagophore membrane. We reconstituted these two reactions and their coupling by WIPI2, and showed that positive feedback between PI3KC3-C1 and WIPI2 leads to rapid LC3 lipidation by the ATG16L1 complex. AbstractAutophagy degrades cytoplasmic cargo by its delivery to lysosomes within double membrane autophagosomes. Synthesis of the phosphoinositide PI(3)P by the autophagic PI 3-kinase complex I (PI3KC3-C1) and conjugation of ATG8/LC3 proteins to phagophore membranes by the ATG12-ATG5-ATG16L1 (E3) complex are two critical steps in autophagosome biogenesis, connected by WIPI2. Here we present a complete reconstitution of these events. On giant unilamellar vesicles (GUVs), LC3 lipidation is strictly dependent on the recruitment of WIPI2, which in turn depends on PI(3)P. Ectopically targeting E3 to membranes in the absence of WIPI2 is insufficient to support LC3 lipidation, demonstrating that WIPI2 allosterically activates the E3 complex. PI3KC3-C1 and WIPI2 mutually promote the recruitment of each other in a positive feedback loop. When both PI 3kinase and LC3 lipidation reactions were carried out simultaneously, positive feedback between PI3KC3-C1 and WIPI2 led to rapid LC3 lipidation with kinetics similar to those seen in cellular autophagosome formation. 105 132 108 125

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Section: Reconstitution Of Pi(3)p-and Wipi-dependent Lc3 Lipidationsupporting

confidence: 75%

A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy

Fracchiolla

Chang

Hurley

et al. 2019

Preprint

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“…For instance, LDs provide a membrane source for autophagosome biogenesis specifically during starvation-induced autophagy (Shpilka et al, 2015). More recently, a conserved acyl-CoA synthetase (ACS) from yeast was shown to be mobilized on nucleated phagophores where it locally mediates transport of fatty acids (FAs) required for phagophore elongation (Schütter et al, 2020). But how these lipid sources such as LDs and ACS are mobilized to autophagosome biogenesis sites at first?…”

Section: Discussionmentioning

confidence: 99%

The Irish potato famine pathogen subverts host vesicle trafficking to channel starvation-induced autophagy to the pathogen interface

Pandey

Leary

Tümtaş

et al. 2020

Preprint

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Eukaryotic cells deploy autophagy to eliminate invading microbes. In turn, pathogens have evolved 22 effector proteins to counteract antimicrobial autophagy. How and why adapted pathogens co-opt 23 autophagy for their own benefit is poorly understood. The Irish famine pathogen Phythophthora 24 infestans secretes the effector protein PexRD54 that selectively activates an unknown plant 25 autophagy pathway, while antagonizing antimicrobial autophagy. Here we show that PexRD54 26 induces autophagosome formation by bridging small GTPase Rab8a-decorated vesicles with 27 autophagic compartments labelled by the core autophagy protein ATG8CL. Rab8a is required for 28 pathogen-triggered and starvation-induced but not antimicrobial autophagy, revealing that specific 29 trafficking pathways underpin selective autophagy. We discovered that Rab8a contributes to basal 30 immunity against P. infestans, but PexRD54 diverts a sub-population of Rab8a vesicles to lipid 31 droplets that associate with autophagosomes. These are then diverted towards pathogen feeding 32 structures that are accommodated within the host cells. We propose that PexRD54 mimics starvation-33 induced autophagy by channeling host endomembrane trafficking towards the pathogen interface 34 possibly to acquire nutrients. This work reveals that effectors can interconnect independent host 35 compartments to stimulate complex cellular processes that benefit the pathogen. Graphical abstract: 37 38 39 40 41 42 43 44 45 Introduction: 46 47Autophagy is a conserved eukaryotic cellular process that mediates the lysosomal degradation and 48 relocation of cellular cargoes within double-membraned vesicles called autophagosomes (He and 49 Klionsky, 2009; Leidal et al., 2020). Although autophagy is historically considered to be a bulk 50 catabolic pathway tasked with maintaining cellular homeostasis under normal or stress conditions, it 51 is now clear that autophagy can be highly selective in cargo choice (Zaffagnini and Martens, 2016). 52Autophagic cargoes are typically captured during autophagosome formation, a complex process that 53 is regulated by the concerted action of a set of conserved autophagy related proteins (ATG) as well 54 as specialized autophagy adaptors and cargo receptors (Mizushima et al., 2011). These captured 55 cargoes are sorted within the autophagosome during maturation of the isolation membrane (also 56 known as the phagophore) via the specific interactions between cargo receptors and a lipidated form 57 of ATG8, which decorates the phagophore to serve as a docking platform for cargo receptors 58 (Ryabovol and Minibayeva, 2016; Slobodkin and Elazar, 2013). 60The source of the phagophore is still under debate, but its primary source is considered to be the 61 endoplasmic reticulum (ER) (Bernard and Klionsky, 2013; Hamasaki et al., 2013). As the cargo is 62 being captured, the phagophore undergoes massive expansion and finally gets sealed to form a 63 mature autophagosome. Therefore, formation of the autophagosome requires additional lipid supplies 64...

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“…Fatty acid metabolism leads to production of triglycerides, phospholipids and other molecules 27 . Elongation of the phospholipid membranes can be aided by channeling fatty acid into phospholipid synthesis 28 . Modulation of fatty acid metabolism has been shown to impact several viruses such as dengue virus, hepatitis C virus, and Old World alphaviruses 18,29,30 .…”

Section: Inhibition Of Fatty Acid Metabolism Inhibits Sars-cov-2 Replmentioning

confidence: 99%

Inhibitors of VPS34 and lipid metabolism suppress SARS-CoV-2 replication

Silvas

Jureka

Nicolini

et al. 2020

Preprint

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Therapeutics targeting replication of SARS coronavirus 2 (SARS-CoV-2) are urgently needed. Coronaviruses rely on host membranes for entry, establishment of replication centers and egress. Compounds targeting cellular membrane biology and lipid biosynthetic pathways have previously shown promise as antivirals and are actively being pursued as treatments for other conditions. Here, we tested small molecule inhibitors that target membrane dynamics or lipid metabolism. Included were inhibitors of the PI3 kinase VPS34, which functions in autophagy, endocytosis and other processes; Orlistat, an inhibitor of lipases and fatty acid synthetase, is approved by the FDA as a treatment for obesity; and Triacsin C which inhibits long chain fatty acyl-CoA synthetases. VPS34 inhibitors, Orlistat and Triacsin C inhibited virus growth in Vero E6 cells and in the human airway epithelial cell line Calu-3, acting at a post-entry step in the virus replication cycle. Of these the VPS34 inhibitors exhibit the most potent activity.

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Local Fatty Acid Channeling into Phospholipid Synthesis Drives Phagophore Expansion during Autophagy

Cited by 176 publications

References 123 publications

A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy

A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy

The Irish potato famine pathogen subverts host vesicle trafficking to channel starvation-induced autophagy to the pathogen interface

Inhibitors of VPS34 and lipid metabolism suppress SARS-CoV-2 replication

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