title: Simulated microgravity contributes to autophagy induction by regulating AMP-activated protein kinase.
abstract: Exposure to microgravity is supposed to affect almost all biological systems, and we speculated that microgravity is potentially involved in autophagy regulation. A clinostat was used to simulate microgravity, and HEK293 cells that stably express GFP-LC3 were used for sensitive monitoring of autophagy induction. The clinorotation of GFP-LC3 cells resulted in autophagosome formation in the cytoplasm and a change in autophagosomal marker expression. Autophagy induction was accompanied by phosphorylation of AMPK (Thr 172) and by the dephosphorylation of mammalian target of rapamycin. To elucidate the role of AMPK in microgravity-induced autophagy, we suppressed AMPK expression by knockdown via siRNA, which inhibited the induction of autophagy upon exposure to microgravity. In addition, the clinorotation of C2C12 myotube cells resulted in the enlarged and distinctive LC3 spots in the cytoplasm and AMPK activation. These results indicate that simulated microgravity possibly contributes to autophagy induction by regulating AMPK.
authors.affiliation: 1 Division of Biological Science and Technology, Yonsei University , Wonju, Republic of Korea.
authors.forename: Hyun-Wook
authors.initials: HW
authors.lastname: Ryu
authors.forename: Sang-Hun
authors.initials: SH
authors.lastname: Choi
authors.forename: Sim
authors.initials: S
authors.lastname: Namkoong
authors.forename: Ik-Soon
authors.initials: IS
authors.lastname: Jang
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Seo
authors.forename: Inho
authors.initials: I
authors.lastname: Choi
authors.forename: Han-Sung
authors.initials: HS
authors.lastname: Kim
authors.forename: Junsoo
authors.initials: J
authors.lastname: Park
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D001343:Autophagy; D004789:Enzyme Activation; D057809:HEK293 Cells; D006801:Humans; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D014893:Weightlessness
chemical_list: C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases