title: Genome-wide siRNA screen reveals amino acid starvation-induced autophagy requires SCOC and WAC.
abstract: Autophagy is a catabolic process by which cytoplasmic components are sequestered and transported by autophagosomes to lysosomes for degradation, enabling recycling of these components and providing cells with amino acids during starvation. It is a highly regulated process and its deregulation contributes to multiple diseases. Despite its importance in cell homeostasis, autophagy is not fully understood. To find new proteins that modulate starvation-induced autophagy, we performed a genome-wide siRNA screen in a stable human cell line expressing GFP-LC3, the marker-protein for autophagosomes. Using stringent validation criteria, our screen identified nine novel autophagy regulators. Among the hits required for autophagosome formation are SCOC (short coiled-coil protein), a Golgi protein, which interacts with fasciculation and elongation protein zeta 1 (FEZ1), an ULK1-binding protein. SCOC forms a starvation-sensitive trimeric complex with UVRAG (UV radiation resistance associated gene) and FEZ1 and may regulate ULK1 and Beclin 1 complex activities. A second candidate WAC is required for starvation-induced autophagy but also acts as a potential negative regulator of the ubiquitin-proteasome system. The identification of these novel regulatory proteins with diverse functions in autophagy contributes towards a fuller understanding of autophagosome formation.
authors.affiliation: Secretory Pathways Laboratory, London Research Institute, Cancer Research UK, London, UK.
authors.forename: Nicole C
authors.initials: NC
authors.lastname: McKnight
authors.forename: Harold B J
authors.initials: HB
authors.lastname: Jefferies
authors.forename: Endalkachew A
authors.initials: EA
authors.lastname: Alemu
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Saunders
authors.forename: Michael
authors.initials: M
authors.lastname: Howell
authors.forename: Terje
authors.initials: T
authors.lastname: Johansen
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Tooze
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D001343:Autophagy; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002460:Cell Line; D020868:Gene Silencing; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010588:Phagosomes / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013194:Staining and Labeling
chemical_list: D000596:Amino Acids; D002352:Carrier Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C430910:SCOC protein, human; C485420:WBP4 protein, human; D049452:Green Fluorescent Proteins