title: Granulocyte-colony stimulating factor activates JAK2/PI3K/PDE3B pathway to inhibit corticosterone synthesis in a neonatal hypoxic-ischemic brain injury rat model.
abstract: OBJECTIVE
  Our previous study demonstrated that granulocyte-colony stimulating factor (G-CSF)-induced neuroprotection is accompanied by an inhibition of corticosterone production in a neonatal hypoxic-ischemic (HI) rat model. The present study investigates how G-CSF inhibits corticosterone production, using adrenal cortical cells and HI rat pups.
  
  
  METHODS
  Cholera toxin was used to induce corticosterone synthesis in a rodent Y1 adrenal cortical cell line by increasing cyclic adenosine monophosphate (cAMP). Both corticosterone and cAMP were quantitatively measured using a commercial enzyme-linked immunosorbent assay (ELISA). The downstream signaling components of the G-CSF receptor, including Janus Kinase 2 (JAK2)/Phosphatidylinositol-3-kinase (PI3K)/Protein kinase B (Akt) and Phosphodiesterase 3B (PDE3B), were detected by western blot. Sprague-Dawley rat pups at the age of 10days (P10) were subjected to unilateral carotid artery ligation followed by hypoxia for 2.5hours. Brain infarction volumes were determined using 2,3,5-triphenyltetrazolium chloride monohydrate (TTC) staining.
  
  
  RESULTS
  G-CSF at 30ng/ml inhibited corticosterone synthesis but lost its inhibitory effect at higher doses. The inhibitory effect of G-CSF was conferred by interfering with cAMP signaling via the activation of the JAK2/PI3K/PDE3B signaling pathway. The degradation of cAMP by G-CSF signaling reduced corticosterone production. This mechanism was further verified in the neonatal HI brain injury rat model, in which inhibition of PDE3B reversed the protective effects of G-CSF.
  
  
  CONCLUSIONS
  Our data suggest that the neuroprotective G-CSF reduces corticosterone synthesis at the adrenal level by degrading intracellular cAMP via activation of the JAK2/PI3K/PDE3B pathway.
authors: Department of Microbiology and Molecular Genetics, Loma Linda University School of Medicine, Loma Linda, CA, 92354 USA; Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA, 92354 USA.
authors: Mélissa S
authors: MS
authors: Charles
authors: Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA, 92354 USA.
authors: Pradilka N
authors: PN
authors: Drunalini Perera
authors: Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA, 92354 USA.
authors: Desislava Met
authors: DM
authors: Doycheva
authors: Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA, 92354 USA. Electronic address: jtang@llu.edu.
authors: Jiping
authors: J
authors: Tang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight / Q000187:drug effects; D020520:Brain Infarction / Q000188:drug therapy / Q000209:etiology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002772:Cholera Toxin / Q000633:toxicity; D003345:Corticosterone / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3 / Q000378:metabolism; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology* / Q000627:therapeutic use; D020925:Hypoxia-Ischemia, Brain / Q000188:drug therapy / Q000378:metabolism*; D053614:Janus Kinase 2 / Q000378:metabolism*; D009410:Nerve Degeneration / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D004791:Enzyme Inhibitors; D016179:Granulocyte Colony-Stimulating Factor; D002772:Cholera Toxin; D000242:Cyclic AMP; D019869:Phosphatidylinositol 3-Kinases; C507927:Jak2 protein, rat; D053614:Janus Kinase 2; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517294:Pde3b protein, rat; D003345:Corticosterone
keywords: Adrenal cortical cells; Cholera toxin; Corticosterone; Granulocyte colony stimulating factor; Hypothalamic-pituitary-adrenal axis; Hypoxia-ischemia; JAK2; PDE; Y1