title: The neuroprotective mechanism of erythropoietin-TAT fusion protein against neurodegeneration from ischemic brain injury.
abstract: OBJECTIVE
  To compare the neuroprotection of erythropoietin (EPO) and EPO fusion protein containing transduction domain derived from HIV TAT (EPO-TAT) against ischemic brain injury, inclusive of the side effect, and explore the mechanism underlying the role of EPO-TAT in a transient focal cerebral ischemia model in rats.
  
  
  METHODS
  Transient focal ischemia was induced by middle cerebral artery occlusion (MCAO) in rats. Rats were treated, respectively, with following regimens: saline, 1000 U/kg EPO, 5000 U/kg EPO, 1000 U/kg EPO-TAT, 1000 U/kg EPOTAT+5 µl of 10 mM LY294002 (or/plus 5 µl of 5 mM PD98059). Neurological deficit scores, infarct volume, and hematologic side effect were assessed at 72 hours after MCAO. Apoptotic cells were determined with TUNEL staining. The expression and localization of phosphorylated AKT (pAKT) and phosphorylated ERK (pERK) were detected with Western blot, immunohistochemistry, and immunofluorescence, respectively.
  
  
  RESULTS
  1000 U/kg EPO-TAT exhibited a comparable neuroprotection to 5000 U/kg EPO, as evidenced by a comparable attenuation in neurological deficit, infarct volume, and number of apoptotic cells in the rat ischemic cortex after MCAO. The pAKT and pERK levels were significantly elevated solely in neurons of rodents receiving EPO or EPO-TAT treatments, suggesting the concurrent activation of these two pathways. Specific inhibition of either AKT or ERK pathway partially abolished EPO-TAT protection, but exhibited no influence on the activation status of its counterpart, suggesting no cross-modulation between these two protective pathways.
  
  
  CONCLUSIONS
  Our study indicates that EPO-TAT at 1000 U/kg displays neuroprotection with no detectable side effects. The mechanism for neuroprotection may be attributable to the simultaneous activation of the AKT and ERK pathways, which preserve neuronal cell viability and attenuate behavioral deficits.
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Liu
authors.forename: Anthony Kian-Fong
authors.initials: AK
authors.lastname: Liou
authors.forename: Juan
authors.initials: J
authors.lastname: Xing
authors.forename: Zheng
authors.initials: Z
authors.lastname: Jing
authors.forename: Xunming
authors.initials: X
authors.lastname: Ji
authors.forename: Xiangrong
authors.initials: X
authors.lastname: Liu
authors.forename: Haiping
authors.initials: H
authors.lastname: Zhao
authors.forename: Feng
authors.initials: F
authors.lastname: Yan
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Guodong
authors.initials: G
authors.lastname: Cao
authors.affiliation: (Yumin Luo) Cerebrovascular Diseases Research Institute, Xuanwu Hospital, Capital Medical University, Key Laboratory of Neurodegenerative Diseases (Capital Medical University), Ministry of Education, 45 Changchun Street, Beijing 100053, P.R. China. yumin111@ccmu.edu.cn.
authors.forename: Yumin
authors.initials: Y
authors.lastname: Luo
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004921:Erythropoietin / Q000627:therapeutic use*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D020244:Infarction, Middle Cerebral Artery / Q000150:complications*; D008297:Male; D019636:Neurodegenerative Diseases / Q000517:prevention & control*; D009460:Neurologic Examination; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D051058:Oncogene Protein v-akt / Q000378:metabolism; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000627:therapeutic use; D018709:Statistics, Nonparametric; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000627:therapeutic use
chemical_list: D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D011993:Recombinant Fusion Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; D004921:Erythropoietin; D051058:Oncogene Protein v-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D010751:Phosphopyruvate Hydratase