CRISPR screens for lipid regulators reveal a role for ER-bound SNX13 in lysosomal cholesterol export

Lü, Aiping; Hsieh, F.; Enrich, Carlos; Pfeffer, Suzanne R

doi:10.1101/2021.05.10.443492

Cited by 2 publications

(1 citation statement)

References 64 publications

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“…However, beyond the coordinated function of Npc1 and 2, other routes for sterol egress from endolysosomes remain poorly understood. Several recent studies in mammalian cells have focused on identifying mechanisms for sterol metabolism, and sterol transport specifically, in control cells and/or in cells in which Npc1 is either genetically or pharmacologically inhibited (Scott et al ., 2015; Trinh et al ., 2020; van den Boomen et al ., 2020; Lu et al ., 2021). We suggest that, given their unique reliance on dietary sterol, Drosophila is an ideal model in which to study mechanisms of sterol egress from the endolysosomal pathway.…”

Section: Discussionmentioning

confidence: 99%

Loss of the GARP but not EARP protein complex drives Golgi sterol overload during dendrite remodeling

Jan

2021

Preprint

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Membrane trafficking is essential for sculpting neuronal morphology. The GARP and EARP complexes are conserved tethers that regulate vesicle trafficking in the secretory and endolysosomal pathways, respectively. Both complexes contain the Vps51, Vps52, and Vps53 proteins, and a complex-specific protein: Vps54 in GARP and Vps50 in EARP. In Drosophila, we find that both complexes are required for dendrite morphogenesis during developmental remodeling of multidendritic class IV da (c4da) neurons. Having found that sterol accumulates at the trans-Golgi network (TGN) in Vps54KO/KO neurons, we investigated genes that regulate sterols and related lipids at the TGN. Overexpression of oxysterol binding protein (Osbp) or knockdown of the PI4K four wheel drive (fwd) exacerbates the Vps54KO/KO phenotype, whereas eliminating one allele of Osbp rescues it, suggesting that excess sterol accumulation at the TGN is, in part, responsible for inhibiting dendrite regrowth. These findings distinguish the GARP and EARP complexes in neurodevelopment and implicate vesicle trafficking and lipid transfer pathways in dendrite morphogenesis.

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Section: Discussionmentioning

confidence: 99%

Loss of the GARP but not EARP protein complex drives Golgi sterol overload during dendrite remodeling

Jan

2021

Preprint

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Structural predictions of the SNX-RGS proteins suggest they belong to a new class of lipid transfer proteins

Paul

Weeratunga

Tillu

et al. 2021

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SummaryRecent advances in protein structure prediction using machine learning such as AlphaFold2 and RosettaFold presage a revolution in structural biology. Genome-wide predictions of protein structures are providing unprecedented insights into their architecture and intradomain interactions, and applications have already progressed towards assessing protein complex formation. Here we present detailed analyses of the sorting nexin proteins that contain regulator of G-protein signalling domains (SNX-RGS proteins), providing a key example of the ability of AlphaFold2 to reveal novel structures with previously unsuspected biological functions. These large proteins are conserved in most eukaryotes and are known to associate with lipid droplets (LDs) and sites of LD-membrane contacts, with key roles in regulating lipid metabolism. Previous studies indicate they possess five domains, including an N-terminal transmembrane domain that anchors them to the endoplasmic reticulum, an RGS domain, a lipid interacting phox homology (PX) domain and two additional domains named the PXA and PXC domains of unknown structure and function. Here we report the crystal structure of the RGS domain of sorting nexin 25 (SNX25) and show that the AlphaFold2 prediction closely matches the experimental structure. Analysing the full-length SNX-RGS proteins across multiple homologues and species we find that the distant PXA and PXC domains in fact fold into a single unique structure that notably features a large and conserved hydrophobic pocket. The nature of this pocket strongly suggests a role in lipid or fatty acid binding, and we propose that these molecules represent a new class of conserved lipid transfer proteins.

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CRISPR screens for lipid regulators reveal a role for ER-bound SNX13 in lysosomal cholesterol export

Cited by 2 publications

References 64 publications

Loss of the GARP but not EARP protein complex drives Golgi sterol overload during dendrite remodeling

Loss of the GARP but not EARP protein complex drives Golgi sterol overload during dendrite remodeling

Structural predictions of the SNX-RGS proteins suggest they belong to a new class of lipid transfer proteins

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