title: Stromal cell derived factor-1 alpha confers protection against myocardial ischemia/reperfusion injury: role of the cardiac stromal cell derived factor-1 alpha CXCR4 axis.
abstract: BACKGROUND
  Stromal cell-derived factor-1alpha (SDF-1alpha) binding to its cognate receptor, CXCR4, regulates a variety of cellular functions such as stem cell homing, trafficking, and differentiation. However, the role of the SDF-1alpha-CXCR4 axis in modulating myocardial ischemia/reperfusion injury is unknown.
  
  
  RESULTS
  In mice subjected to ischemic preconditioning, myocardial SDF-1alpha mRNA was found to be increased 3 hours later (P<0.05). Myocardial SDF-1alpha and CXCR4 mRNA and protein were found to be expressed in both cardiac myocytes and fibroblasts. SDF-1alpha production increased significantly after 1 or 4 hours of hypoxia and 18 hours of reoxygenation in cultured myocytes (P<0.05) but did not change in fibroblast cultures. In isolated myocytes, CXCR4 activation by SDF-1alpha resulted in increased phosphorylation of both ERK 1/2 and AKT and decreased phosphorylation of JNK and p38. Cultured myocytes pretreated with SDF-1alpha were resistant to hypoxia/reoxygenation damage, exhibiting less lactate dehydrogenase release, trypan blue uptake, and apoptotic cell death (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay) (P<0.05). This protective effect was blocked by the CXCR4 selective antagonist AMD3100. In vivo, administration of SDF-1alpha before 30 minutes of coronary occlusion followed by 4 hours of reperfusion decreased infarct size (P<0.05). The decrease in infarct size with SDF-1alpha administration also was blocked by AMD3100.
  
  
  CONCLUSIONS
  We conclude that SDF-1alpha and its receptor, CXCR4, constitute a paracrine or autocrine axis in cardiac myocytes that is activated in response to preconditioning and hypoxic stimuli, recruiting the antiapoptotic kinases ERK and AKT and promoting an antiapoptotic program that confers protection against ischemia/reperfusion damage.
authors.affiliation: Institute of Molecular Cardiology, Division of Cardiology, University of Louisville, Louisville, KY 40202, USA.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Hu
authors.forename: Shujing
authors.initials: S
authors.lastname: Dai
authors.forename: Wen-Jian
authors.initials: WJ
authors.lastname: Wu
authors.forename: Wei
authors.initials: W
authors.lastname: Tan
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Zhu
authors.forename: Jingyao
authors.initials: J
authors.lastname: Mu
authors.forename: Yiru
authors.initials: Y
authors.lastname: Guo
authors.forename: Roberto
authors.initials: R
authors.lastname: Bolli
authors.forename: Gregg
authors.initials: G
authors.lastname: Rokosh
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000502:physiology*; D000860:Hypoxia / Q000378:metabolism / Q000473:pathology; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017202:Myocardial Ischemia / Q000378:metabolism / Q000517:prevention & control*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D032383:Myocytes, Cardiac / Q000502:physiology; D019899:Paracrine Communication / Q000502:physiology; D051381:Rats; D019718:Receptors, CXCR4 / Q000096:biosynthesis / Q000502:physiology*; D017154:Stromal Cells / Q000378:metabolism / Q000502:physiology
chemical_list: D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D019718:Receptors, CXCR4