title: JAK2/STAT5/Bcl-xL signalling is essential for erythropoietin-mediated protection against apoptosis induced in PC12 cells by the amyloid β-peptide Aβ25-35.
abstract: OBJECTIVE
  Erythropoietin (EPO) exerts neuroprotective actions in the CNS, including protection against apoptosis induced by the amyloid β-peptide Aβ25-35 . However, it remains unclear which signalling pathway activated by EPO is involved in this neuroprotection. Here, we have investigated whether JAK2/STAT5/Bcl-xL and ERK1/2 signalling pathways are essential for EPO-mediated protection against apoptosis induced by Aβ25-35 .
  
  
  METHODS
  EPO was added to cultures of PC12 cells, 1 h before Aβ25-35 . For kinase inhibitor studies, AG490 and PD98059 were added to PC12 cells, 0.5 h before the addition of EPO. Transfection with siRNA was used to knockdown STAT5. Activation of JAK2/STAT5/Bcl-xL and ERK1/2 signalling pathways were investigated by Western blotting. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl-tetrazolium bromide assay and apoptosis was detected by TUNEL and acridine orange-ethidium bromide double staining.
  
  
  RESULTS
  EPO increased phosphorylation of JAK2 and STAT5 in PC12 cells treated with Aβ25-35 . Furthermore, EPO modulated the nuclear translocation of phospho-STAT5, which increased expression of Bcl-xL and decreased levels of caspase-3. These beneficial effects were blocked by the JAK2 inhibitor, AG490 or STAT5 knockdown. However, the ERK1/2 pathway did not play a crucial role in our model.
  
  
  CONCLUSIONS
  EPO protected PC12 cells against Aβ25-35 -induced neurotoxicity. Activation of JAK2/STAT5/Bcl-xL pathway was important in EPO-mediated neuroprotection. EPO may serve as a novel protective agent against Aβ25-35 -induced cytotoxicity in, for instance, Alzheimer's disease.
authors.affiliation: Department of Pharmacology, Tongji Medical College of Huazhong University of Science & Technology, Wuhan, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Ma
authors.forename: Jing
authors.initials: J
authors.lastname: Hu
authors.forename: Chengfang
authors.initials: C
authors.lastname: Huang
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Jizhou
authors.initials: J
authors.lastname: Xiang
authors.forename: Gang
authors.initials: G
authors.lastname: Li
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004921:Erythropoietin / Q000494:pharmacology*; D055785:Gene Knockdown Techniques; D020287:In Situ Nick-End Labeling; D053614:Janus Kinase 2 / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016716:PC12 Cells; D010446:Peptide Fragments / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D034741:RNA, Small Interfering / Q000008:administration & dosage; D051381:Rats; D050799:STAT5 Transcription Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D034741:RNA, Small Interfering; D050799:STAT5 Transcription Factor; C074636:amyloid beta-protein (25-35); D051020:bcl-X Protein; D004921:Erythropoietin; C507927:Jak2 protein, rat; D053614:Janus Kinase 2; D053148:Caspase 3
keywords: Aβ; ERK1/2; JAK2/STAT5; apoptosis; erythropoietin; kinase inhibitor