title: Cross-talk between autophagy and KLF2 determines endothelial cell phenotype and microvascular function in acute liver injury.
abstract: The transcription factor Krüppel-like factor 2 (KLF2), inducible by simvastatin, confers endothelial vasoprotection. Considering recent data suggesting activation of autophagy by statins, we aimed to: 1) characterize the relationship between autophagy and KLF2 in the endothelium, 2) assess this relationship in acute liver injury (cold ischemia/reperfusion) and 3) study the effects of modulating KLF2-autophagy in vitro and in vivo.
  
  
  
  Autophagic flux, the vasoprotective KLF2 pathway, cell viability and microvascular function were assessed in endothelial cells and in various pre-clinical models of acute liver injury (cold storage and warm reperfusion).
  
  
  
  Positive feedback between autophagy and KLF2 was observed in the endothelium: KLF2 inducers, pharmacological (statins, resveratrol, GGTI-298), biomechanical (shear stress) or genetic (adenovirus containing KLF2), caused endothelial KLF2 overexpression through a Rac1-rab7-autophagy dependent mechanism, both in the specialized liver sinusoidal endothelial cells (LSEC) and in human umbilical vein endothelial cells. In turn, KLF2 induction promoted further activation of autophagy. Cold ischemia blunted autophagic flux. Upon reperfusion, LSEC stored in University of Wisconsin solution did not reactivate autophagy, which resulted in autophagosome accumulation probably due to impairment in autophagosome-lysosome fusion, ultimately leading to increased cell death and microvascular dysfunction. Simvastatin pretreatment maintained autophagy (through the upregulation of rab7), resulting in increased KLF2, improved cell viability, and ameliorated hepatic damage and microvascular function.
  
  
  
  We herein describe for the first time the complex autophagy-KLF2 relationship, modulating the phenotype and survival of the endothelium. These results help understanding the mechanisms of protection conferred by KLF2-inducers, such as simvastatin, in hepatic vascular disorders.
  
  
  
  Autophagy and the transcription factor KLF2 share a common activation pathway in the endothelium, being able to regulate each other. Statins maintain microvascular function through the inhibition of Rac1, which consequently liberates Rab7, activates autophagy and increments the expression of KLF2.
authors.affiliation: Barcelona Hepatic Hemodynamic Lab., IDIBAPS - Hospital Clínic - CIBEREHD, University of Barcelona Medical School, Barcelona, Spain.
authors.forename: Sergi
authors.initials: S
authors.lastname: Guixé-Muntet
authors.affiliation: Barcelona Hepatic Hemodynamic Lab., IDIBAPS - Hospital Clínic - CIBEREHD, University of Barcelona Medical School, Barcelona, Spain; Laboratório de Biofisica Celular e Inflamação, Pontificia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, RS, Brazil.
authors.forename: Fernanda Cristina
authors.initials: FC
authors.lastname: de Mesquita
authors.affiliation: Barcelona Hepatic Hemodynamic Lab., IDIBAPS - Hospital Clínic - CIBEREHD, University of Barcelona Medical School, Barcelona, Spain.
authors.forename: Sergi
authors.initials: S
authors.lastname: Vila
authors.affiliation: Barcelona Hepatic Hemodynamic Lab., IDIBAPS - Hospital Clínic - CIBEREHD, University of Barcelona Medical School, Barcelona, Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: Hernández-Gea
authors.affiliation: IDIBAPS & CIBEREHD, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Peralta
authors.affiliation: Barcelona Hepatic Hemodynamic Lab., IDIBAPS - Hospital Clínic - CIBEREHD, University of Barcelona Medical School, Barcelona, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: García-Pagán
authors.affiliation: Barcelona Hepatic Hemodynamic Lab., IDIBAPS - Hospital Clínic - CIBEREHD, University of Barcelona Medical School, Barcelona, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Bosch
authors.affiliation: Barcelona Hepatic Hemodynamic Lab., IDIBAPS - Hospital Clínic - CIBEREHD, University of Barcelona Medical School, Barcelona, Spain. Electronic address: jordi.gracia@idibaps.org.
authors.forename: Jordi
authors.initials: J
authors.lastname: Gracia-Sancho
mesh_terms: D001343:Autophagy / Q000502:physiology*; D002470:Cell Survival; D004730:Endothelium, Vascular / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D017114:Liver Failure, Acute / Q000378:metabolism / Q000517:prevention & control; D055806:Microvessels / Q000378:metabolism / Q000503:physiopathology; D008954:Models, Biological; D020011:Protective Agents / Q000494:pharmacology; D015427:Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000090802:rab7 GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; C096161:KLF2 protein, human; D051741:Kruppel-Like Transcription Factors; D020011:Protective Agents; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; D020691:rab GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein
keywords: HUVEC; Ischemia/reperfusion; LSEC; Rab7; Rac1; Simvastatin; Statins