Hypoxic preconditioning induces stroke tolerance in mice via a cascading HIF, sphingosine kinase, and CCL2 signaling pathway

J Neurochem. 2012 Dec;123(6):954-62. doi: 10.1111/jnc.12047. Epub 2012 Nov 1.


The induction of ischemic tolerance by preconditioning provides a platform to elucidate endogenous mechanisms of stroke protection. In these studies, we characterize the relationship between hypoxia-inducible factor (HIF), sphingosine kinase 2 (SphK2), and chemokine (C-C motif) ligand 2 (CCL2) in models of hypoxic or pharmacological preconditioning-induced ischemic tolerance. A genetics-based approach using SphK2- and CCL2-null mice showed both SphK2 and CCL2 to be necessary for the induction of ischemic tolerance following preconditioning with hypoxia, the hypoxia-mimetic cobalt chloride, or the sphingosine-1-phosphate (S1P) agonist FTY720. A pharmacological approach confirmed the necessity of HIF signaling for all three preconditioning stimuli, and showed that the SphK/S1P pathway transduces tolerance via the S1P(1) receptor. In addition, our data suggest significant cross-talk between HIF and SphK2-produced S1P signaling, which together act to up-regulate CCL2 expression. Overall, HIF, SphK, S1P, and CCL2 participate in a signaling cascade to induce the gene expression responsible for the stroke-tolerant phenotype established by hypoxic and FTY720 preconditioning. The identification of these common molecular mediators involved in signaling the genomic response to multiple preconditioning stimuli provides several targets for therapeutic manipulation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CX3C Chemokine Receptor 1
  • Chemokine CCL2 / deficiency
  • Chemokine CCL2 / genetics
  • Chemokine CCL2 / physiology*
  • Enzyme Inhibitors / pharmacology
  • Female
  • Hypoxia-Inducible Factor 1, alpha Subunit / physiology*
  • Hypoxia-Ischemia, Brain / metabolism*
  • Hypoxia-Ischemia, Brain / therapy
  • Ischemic Preconditioning / methods*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Phenotype
  • Phosphotransferases (Alcohol Group Acceptor) / antagonists & inhibitors*
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Receptors, Chemokine / deficiency
  • Receptors, Chemokine / genetics
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*
  • Stroke / drug therapy
  • Stroke / enzymology
  • Stroke / metabolism*


  • CX3C Chemokine Receptor 1
  • Ccl2 protein, mouse
  • Chemokine CCL2
  • Cx3cr1 protein, mouse
  • Enzyme Inhibitors
  • Hif1a protein, mouse
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Receptors, Chemokine
  • Phosphotransferases (Alcohol Group Acceptor)
  • sphingosine kinase