Identification of glucose-6-phosphate transporter as a key regulator functioning at the autophagy initiation step

• Published in: FEBS letters 2015-07, Vol.589 (16), p.2100-2109
• Main Authors: Ahn, Hye-Hyun, Oh, Yumin, Lee, Huikyong, Lee, WonJae, Chang, Jae-Woong, Pyo, Ha-Kyung, Nah, Do hyung, Jung, Yong-Keun
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Animals; Antiporters - antagonists & inhibitors; Antiporters - genetics; Antiporters - metabolism; ATG9; Autophagy; Autophagy modulator; Autophagy-Related Protein-1 Homolog; Autophagy-Related Proteins; BiFC; bimolecular fluorescence complementation; C-terminus of Venus vector; Cell Line; CHA; chlorogenic acid; Cricetulus; G6PT; glucose-6-phosphate transporter; Hepatocytes - cytology; Hepatocytes - enzymology; Hepatocytes - metabolism; Humans; Huntingtin Protein; Intracellular Signaling Peptides and Proteins - chemistry; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - metabolism; Mechanistic Target of Rapamycin Complex 1; Membrane Proteins - chemistry; Membrane Proteins - genetics; Membrane Proteins - metabolism; Models, Biological; Monosaccharide Transport Proteins - antagonists & inhibitors; Monosaccharide Transport Proteins - genetics; Monosaccharide Transport Proteins - metabolism; Multiprotein Complexes - antagonists & inhibitors; Multiprotein Complexes - metabolism; Mutant Proteins - chemistry; Mutant Proteins - metabolism; N-terminus of Venus vector; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptide Fragments - metabolism; Phagosomes - enzymology; Phagosomes - metabolism; Protein Interaction Domains and Motifs; Protein Serine-Threonine Kinases - chemistry; Protein Serine-Threonine Kinases - genetics; Protein Serine-Threonine Kinases - metabolism; Protein Transport; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; RNA Interference; Screening; TOR Serine-Threonine Kinases - antagonists & inhibitors; TOR Serine-Threonine Kinases - metabolism; ULK1; Up-Regulation; Vesicular Transport Proteins - chemistry; Vesicular Transport Proteins - genetics; Vesicular Transport Proteins - metabolism
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/j.febslet.2015.05.018

•ULK1 interacts with ATG9 in mammalian cells.•ULK1-VN/ATG9-VC BiFC assay isolated a new autophagy modulator.•G6PT regulates autophagic flux independent of its enzyme activity.•G6PT negatively regulates mTORC1 activity. Autophagy is a catabolic process involving autophagosome formation via lysosome. However, the initiation step of autophagy is largely unknown. We found an interaction between ULK1 and ATG9 in mammalian cells and utilized the interaction to identify novel regulators of autophagy upstream of ULK1. We established a cell-based screening assay employing bimolecular fluorescence complementation. By performing gain-of-function screening, we identified G6PT as an autophagy activator. G6PT enhanced the interaction between N-terminal Venus-tagged ULK1 and C-terminal Venus-tagged ATG9, and increased autophagic flux independent of its transport activity. G6PT negatively regulated mTORC1 activity, demonstrating that G6PT functions upstream of mTORC1 in stimulating autophagy.