title: Chloroquine increases phosphorylation of AMPK and Akt in myotubes.
abstract: OBJECTIVE
  There are reports that ataxia telangiectasia mutated (ATM) can activate the AMP-activated protein kinase (AMPK) and also Akt, two kinases that play integral parts in cardioprotection and metabolic function. We hypothesized that chloroquine and resveratrol, both known ATM activators, would also activate AMPK and Akt.
  
  
  METHODS
  Phosphorylation of AMPK and Akt was assessed after C2C12 myotubes were exposed to chloroquine or resveratrol. Additional experiments were done in cells expressing shRNA against ATM or in the presence of the ATM inhibitor KU55933. The effects of chloroquine on intracellular calcium were assessed with the fluorescent probe Calcium Green-1 AM.
  
  
  RESULTS
  0.5 mM chloroquine increased AMPK phosphorylation by nearly 4-fold (P<0.05), and 0.25 mM chloroquine roughly doubled Akt phosphorylation (P<0.05). Chloroquine also increased autophosphorylation of ATM by ~50% (P<0.05). Resveratrol (0.15 mM) increased AMPK phosphorylation about three-fold (P<0.05) but in contrast to chloroquine sharply decreased Akt phosphorylation. Chloroquine increased AMPK and Akt phosphorylation in myotubes expressing shRNA against ATM that reduced ATM protein levels by about 90%. Likewise, chloroquine-stimulated phosphorylation of AMPK and Akt and resveratrol-stimulated phosphorylation of AMPK were not altered by inhibition of ATM. Chloroquine decreased intracellular calcium by >50% concomitant with a decrease in glucose transport.
  
  
  CONCLUSIONS
  These ATM-independent effects of chloroquine on AMPK and Akt and the additional effect to decrease intracellular calcium are likely to partially underlie the positive metabolic effects of chloroquine that have been reported in the literature.
authors.affiliation: Department of Biology, Saint Louis University, St. Louis, MO 63103,USA.
authors.forename: Larry D
authors.initials: LD
authors.lastname: Spears
authors.affiliation: Department of Biology, Saint Louis University, St. Louis, MO 63103,USA.
authors.forename: Andrew V
authors.initials: AV
authors.lastname: Tran
authors.affiliation: Department of Biology, Saint Louis University, St. Louis, MO 63103,USA.
authors.forename: Charles Y
authors.initials: CY
authors.lastname: Qin
authors.affiliation: Department of Biology, Saint Louis University, St. Louis, MO 63103,USA.
authors.forename: Supriya B
authors.initials: SB
authors.lastname: Hobbs
authors.affiliation: Department of Biology, Saint Louis University, St. Louis, MO 63103,USA.
authors.forename: Cheryl A Liang
authors.initials: CA
authors.lastname: Burns
authors.affiliation: Department of Biology, Saint Louis University, St. Louis, MO 63103,USA.
authors.forename: Nathaniel K
authors.initials: NK
authors.lastname: Royer
authors.affiliation: Sigma-Aldrich, St. Louis, MO 63103,USA.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Sigma-Aldrich, St. Louis, MO 63103,USA.
authors.forename: Lyle
authors.initials: L
authors.lastname: Ralston
authors.affiliation: Department of Biology, Saint Louis University, St. Louis, MO 63103,USA; Center for Cardiovascular Research, Saint Louis University, St. Louis, MO 63103,USA.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Fisher
keywords: Animal metabolism; Applied sciences; Therapeutics in cell biology