title: Stearoyl-CoA desaturase 1 activity is required for autophagosome formation.
abstract: Autophagy is one of the major degradation pathways for cytoplasmic components. The autophagic isolation membrane is a unique membrane whose content of unsaturated fatty acids is very high. However, the molecular mechanisms underlying formation of this membrane, including the roles of unsaturated fatty acids, remain to be elucidated. From a chemical library consisting of structurally diverse compounds, we screened for novel inhibitors of starvation-induced autophagy by measuring LC3 puncta formation in mouse embryonic fibroblasts stably expressing GFP-LC3. One of the inhibitors we identified, 2,5-pyridinedicarboxamide, N2,N5-bis[5-[(dimethylamino)carbonyl]-4-methyl-2-thiazolyl], has a molecular structure similar to that of a known stearoyl-CoA desaturase (SCD) 1 inhibitor. To determine whether SCD1 inhibition influences autophagy, we examined the effects of the SCD1 inhibitor 28c. This compound strongly inhibited starvation-induced autophagy, as determined by LC3 puncta formation, immunoblot analyses of LC3, electron microscopic observations, and p62/SQSTM1 accumulation. Overexpression of SCD1 or supplementation with oleic acid, which is a catalytic product of SCD1 abolished the inhibition of autophagy by 28c. Furthermore, 28c suppressed starvation-induced autophagy without affecting mammalian target of rapamycin activity, and also inhibited rapamycin-induced autophagy. In addition to inhibiting formation of LC3 puncta, 28c also inhibited formation of ULK1, WIPI1, Atg16L, and p62/SQSTM1 puncta. These results suggest that SCD1 activity is required for the earliest step of autophagosome formation.
authors.affiliation: From the Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Ogasawara
authors.affiliation: the Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo 113-8519, and.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Itakura
authors.affiliation: the Graduate School of Pharmaceutical Sciences and.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Kono
authors.affiliation: the Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo 113-8519, and Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Mizushima
authors.affiliation: the Graduate School of Pharmaceutical Sciences and.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Arai
authors.affiliation: From the Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829.
authors.forename: Atsuki
authors.initials: A
authors.lastname: Nara
authors.affiliation: From the Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829.
authors.forename: Tamio
authors.initials: T
authors.lastname: Mizukami
authors.affiliation: From the Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, a_yamamoto@nagahama-i-bio.ac.jp.
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D001343:Autophagy; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D005227:Fatty Acids / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D010588:Phagosomes / Q000378:metabolism*; D021381:Protein Transport; D060888:Real-Time Polymerase Chain Reaction; D013230:Stearoyl-CoA Desaturase / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D005227:Fatty Acids; C490333:Scd1 protein, mouse; D013230:Stearoyl-CoA Desaturase
keywords: Autophagy; Endoplasmic Reticulum (ER); Fatty Acid; Lipid Metabolism; Membrane; SCD1