The MAP1-LC3 conjugation system is involved in lipid droplet formation.
Lipid droplets (LDs) are ubiquitous in eukaryotic cells, while excess free fatty acids and glucose in plasma are converted to triacylglycerol (TAG) and stored as LDs. However, the mechanism for the generation and growth of LDs in cells is largely unknown. We show here that the LC3 lipidation system essential for macroautophagy is involved in LD formation. LD formation accompanied by accumulation of TAG induced by starvation was largely suppressed in the hepatocytes that cannot execute autophagy. Under starvation conditions, LDs in addition to autophagosomes were abundantly formed in the cytoplasm of these tissue cells. Moreover, LC3 was localized on the surface of LDs and LC3-II (lipidation form) was fractionated to a perilipin (LD marker)-positive lipid fraction from the starved liver. Taken together, these results indicate that the LC3 conjugation system is critically involved in lipid metabolism via LD formation.
Shibata
Masahiro
M
Department of Cell Biology and Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Yoshimura
Kentaro
K
Furuya
Norihiko
N
Koike
Masato
M
Ueno
Takashi
T
Komatsu
Masaaki
M
Arai
Hiroyuki
H
Tanaka
Keiji
K
Kominami
Eiki
E
Uchiyama
Yasuo
Y
D000818:Animals; D001343:Autophagy; D000071193:Autophagy-Related Protein 7; D006321:Heart; D022781:Hepatocytes / Q000378:metabolism; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism*; D051379:Mice; D008817:Mice, Mutant Strains; D008869:Microtubule-Associated Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010588:Phagosomes / Q000378:metabolism; D051381:Rats
C502661:Atg7 protein, mouse; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; D000071193:Autophagy-Related Protein 7