title: Inhibition of autophagy by chloroquine stimulates nitric oxide production and protects endothelial function during serum deprivation.
abstract: OBJECTIVE
  Autophagy plays a fundamental role in cell survival under stress conditions such as nutrient deprivation. Decreased nitric oxide (NO) production, which may contribute to vascular dysfunction, is one of the consequences of autophagy in endothelial cells. The antimalarial drug chloroquine (CLQ) inhibits autophagy by blocking autophagosome formation and has been proposed as adjuvant chemotherapy in other diseases.
  
  
  METHODS
  Autophagy was induced by serum deprivation in Human Umbilical Vascular Endothelial Cells (HUVEC) as demonstrated by formation of Acidic Vesicular Organelles (AVOs), conversion of Microtubule-associated protein 1 light chain (LC3), and Sequestosome-1 (SQTM1/p62) degradation. Using endothelium-dependent vasorelaxation assays, intracellular NO production in an ex vivo rat aortic ring model pre-constricted with phenylephrine was estimated along with DAF-2 DA cell membrane-permeable NO sensitive fluorescent dye.
  
  
  RESULTS
  The inhibition of autophagy by CLQ restored NO levels, protected against superoxide generation and preserved morphology as well as proliferation of HUVEC under serum deprivation. Interestingly, the incubation of rat aortic rings with CLQ resulted in endothelium-dependent relaxation mediated by the increase of NO.
  
  
  CONCLUSIONS
  These findings emphasize the importance of autophagy in endothelial function and demonstrate the potential use of autophagy inhibitors to protect vascular function during nutrient deprivation.
authors.forename: Cezar Rangel
authors.initials: CR
authors.lastname: Pestana
authors.forename: Jorge Camargo
authors.initials: JC
authors.lastname: Oishi
authors.forename: Heloísa Sobreiro
authors.initials: HS
authors.lastname: Salistre-Araújo
authors.forename: Gerson Jhonatan
authors.initials: GJ
authors.lastname: Rodrigues
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002738:Chloroquine / Q000494:pharmacology*; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D000071456:Sequestosome-1 Protein; D014664:Vasodilation / Q000187:drug effects
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; D009569:Nitric Oxide; D002738:Chloroquine