title: Rac1 contributes to cerebral ischemia reperfusion-induced injury in mice by regulation of Notch2.
abstract: BACKGROUND
  Cerebral ischemia-reperfusion (IR) injury is a complex pathological process that can cause irreversible brain damage, neuronal injury or death from brain ischemia. Rac1 GTPase is involved in cellular protection from IR injury. However, the mechanism of protection and the molecules affected by Rac1 remain to be defined.
  
  
  RESULTS
  C57BL/6 mice were subjected to middle cerebral artery occlusion for 1h, followed by 24-h reperfusion. In this in vivo model of cerebral IR injury, mice treated with the Rac GTPase inhibitor NSC23766 or Rac1 small interfering RNA (siRNA) had better short-term (72 h) neurologic scores, less infarction volume, higher production of antioxidant enzymes, lower lipid peroxide, and reduced apoptosis compared with a vehicle-treated group or a control-siRNA group. However, long-term (14 day) neurologic scores were worse for the two treatments compared to controls. Microarray and quantitative polymerase chain reaction (PCR) revealed that Notch2 was downregulated under NSC23766 treatment. Notch2 protein levels decreased with NSC23766 and Rac1 siRNA in vitro and in vivo. Cell survival increased with the Notch signaling inhibitor DAPT or Notch2 siRNA and NICD2 attenuated the NSC23766 effect. In addition, immunoblotting showed that DAPT and Notch2 siRNA changed the levels of apoptosis-regulating proteins. NFkB mediated Rac1, which regulated Notch2 in an oxygen glucose deprivation model. Both inhibitors of Notch2 and Rac1 enhanced neural stem cell differentiation.
  
  
  CONCLUSIONS
  This study demonstrated the importance of Rac1 regulation of Notch2 in mediating cerebral IR-induced production of injurious reactive oxygen species and cell death in vitro and in vivo in the short term. Targeted inhibition of Rac1 or Notch2 is new avenue for in vivo therapy aimed at protecting organs at risk from IR injury.
authors: Harbin Medical University, Harbin 150001, China.
authors: S
authors: S
authors: Meng
authors: Harbin Medical University, Harbin 150001, China. Electronic address: zhiqiangsu70@163.com.
authors: Z
authors: Z
authors: Su
authors: The Fourth Affiliated Hospital of Harbin Medical University, Harbin 150001, China.
authors: Z
authors: Z
authors: Liu
authors: The Fourth Hospital of Harbin, Harbin 150001, China.
authors: N
authors: N
authors: Wang
authors: Department of Pharmacology, the Fourth Military Medical University, Xi'an 710032, China.
authors: Z
authors: Z
authors: Wang
mesh_terms: D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002545:Brain Ischemia / Q000503:physiopathology* / Q000517:prevention & control; D000066673:Cell Self Renewal / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism; D009479:Neuropeptides / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology*; D011743:Pyrimidines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D051883:Receptor, Notch2 / Q000378:metabolism*; D015427:Reperfusion Injury / Q000503:physiopathology* / Q000517:prevention & control; D015398:Signal Transduction / Q000187:drug effects; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology*
chemical_list: D000634:Aminoquinolines; D016328:NF-kappa B; C487513:NSC 23766; D009479:Neuropeptides; C497765:Notch2 protein, mouse; D011743:Pyrimidines; D034741:RNA, Small Interfering; C484602:Rac1 protein, mouse; D017382:Reactive Oxygen Species; D051883:Receptor, Notch2; D020830:rac1 GTP-Binding Protein
keywords: Notch2; Rac1 GTPase; cerebral ischemia reperfusion; neuron protection