LC3, a microtubule-associated protein1A/B light chain3, is involved in cytoplasmic lipid droplet formation
Section snippets
Materials and methods
Antibodies. Antibodies to rat full-length LC3 were prepared by immunizing the recombinant rat full-length LC3 protein [13]. Anti-GAPDH and anti-perilipin antibodies were purchased from Ambion and Progen, respectively.
RNA interference of LC3. The oligonucleotide sequences synthesized for RNAi were listed in Table S1. Two complementary oligonucleotides were annealed and subcloned into pSuper_neo vector (Oligoengine, USA). RNAi vectors were transfected into various types of cells using
Induction of LDs in PC12 cells during cultures for 12 h.
Since the LC3 conjugation system is involved in LD formation in hepatocytes and cardiac myocytes [7], we further examined roles of LC3 in LD formation using cultured tumor cells such as PC12, HeLa, COS1, and HepG2 cells. It has been shown that LDs temporally accumulate in the cultured cell lines during proliferation [22]. We therefore analyzed whether LDs are produced during cultures of the cells in which they were seeded at a density of 70% confluence in culture dishes. When stained for
Discussion
Although in vivo tissue cells are different from proliferating cultured cells, an increase in LDs has also been shown in rodent peripheral tissue cells, especially in hepatocytes and cardiac myocytes when the animals were starved for 24 and 48 h [7]. Fat cells in adipose tissues release FFAs under starvation conditions, while hepatocytes and cardiac myocytes take up released FFAs and store them as LDs to some extent [24]. Thus, it seems likely that such response of peripheral tissue cells to
Acknowledgments
This work was supported by a Grant-in-aid for Creative Scientific Research (to Y.U., M.K., M.S. M.S. and T.U.) from the Japan Society for the Promotion of Science.
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2021, Life SciencesCitation Excerpt :Singh et al. found an autophagy-mediated lipolytic function and term “lipophagy” [39]. The autophagosomal protein LC3 may function in lipid droplet recognition since it has been associated with lipid droplets in the apparent absence of autophagosomal membrane [40–42]. And it was reported that H2S reduced serum TG by activating liver autophagy via the AMPK-mTOR pathway [12].