The Neuroprotective Mechanism of Erythropoietin-TAT Fusion Protein Against Neurodegeneration from Ischemic Brain Injury

Author(s): Ping Liu, Xiaolei Liu, Anthony Kian-Fong Liou, Juan Xing, Zheng Jing, Xunming Ji, Xiangrong Liu, Haiping Zhao, Feng Yan, Jun Chen, Guodong Cao, Yumin Luo.

Journal Name: CNS & Neurological Disorders - Drug Targets
(Formerly Current Drug Targets - CNS & Neurological Disorders)

Volume 13 , Issue 8 , 2014

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Aims: 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.

Conclusion: 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.

Keywords: Cerebral ischemia, erythropoietin, neurodegeneration, neuroprotection, reperfusion.

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Article Details

Year: 2014
Page: [1465 - 1474]
Pages: 10
DOI: 10.2174/1871527313666140806155259
Price: $58

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