title: Atorvastatin induces autophagy of mesenchymal stem cells under hypoxia and serum deprivation conditions by activating the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway.
abstract: BACKGROUND
  The survival ratio of implanted mesenchymal stem cells (MSCs) in the infarcted myocardium is low. Autophagy is a complex "self-eating" process and can be utilized for cell survival. We have found that atorvastatin (ATV) can effectively activate autophagy to enhance MSCs survival during hypoxia and serum deprivation (H/SD). The mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK/ERK) pathway is a non-canonical autophagy pathway. We hypothesized that the MEK/ERK pathway mediated ATV-induced autophagy of MSCs under H/SD.
  
  
  METHODS
  MSCs were pretreated with ATV (0.01-10 µmol/L) under H/SD for three hours. For inhibitor studies, the cells were pre-incubated with the MEK1/2 inhibitor U0126. Cell autophagy was assessed by acidic vesicular organelles (AVO)-positive cells using flow cytometry, autophagy related protein using Western blotting and autophagosome using transmission electron microscopy.
  
  
  RESULTS
  Autophagy was elevated in the H/SD group compared with the normal group. ATV further enhanced the autophagic activity as well as the phosphorylation of ERK1/2 evidenced by more AVO-positive cells ((8.63 ± 0.63)% vs. (5.77 ± 0.44)%, P < 0.05), higher LC3-II/LC3-I ratio (4.36 ± 0.31 vs. 2.52 ± 0.18, P < 0.05) and more autophagosomes. And treatment with U0126 downregulated the phosphorylation of ERK1/2 and attenuated ATV-induced autophagy.
  
  
  CONCLUSIONS
  The MEK/ERK pathway participates in ATV-induced autophagy in MSCs under H/SD, and modulation of the pathway could be a novel strategy to improve MSCs survival.
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Qian
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China. Email: yangyjfw@126.com.
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
authors.forename: Runlin
authors.initials: R
authors.lastname: Gao
mesh_terms: D000818:Animals; D000069059:Atorvastatin; D001343:Autophagy / Q000187:drug effects*; D015687:Cell Hypoxia / Q000502:physiology; D002478:Cells, Cultured; D005434:Flow Cytometry; D006538:Heptanoic Acids / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D011758:Pyrroles / Q000494:pharmacology*; D051381:Rats
chemical_list: D006538:Heptanoic Acids; D011758:Pyrroles; D000069059:Atorvastatin