title: Phosphorylation of PTEN and Akt in astrocytes of the rat hippocampus following transient forebrain ischemia.
abstract: To ascertain whether the PTEN (phosphatase and tensin homolog deleted on chromosome 10)/Akt signaling pathway is activated during ischemic brain injury, we investigated the expression and phosphorylation of PTEN and Akt by immunohistochemistry in the rat hippocampus after transient forebrain ischemia. Weak immunoreactivity for PTEN and its phosphorylated form (p-PTEN) was constitutively expressed in hippocampal neurons and astrocytes of the control rats, but their upregulation was detected mainly in reactive astrocytes in the ischemic hippocampus. Increased immunoreactivity for PTEN and p-PTEN occurred specifically in astrocytes by day 1 and was sustained for more than 2 weeks. The spatiotemporal activation of Akt in the ischemic hippocampus mirrored that of p-PTEN expression. Post-ischemic activation of Akt, revealed by phosphorylated Akt (p-Akt) immunoreactivity, was first detected at day 1 and was maintained for at least 2 weeks. Double-labeling experiments revealed that the cells expressing PTEN, p-PTEN, or p-Akt were reactive astrocytes expressing glial fibrillary acidic protein. These results demonstrate the increased phosphorylation of PTEN and Akt in reactive astrocytes of the post-ischemic hippocampus, suggesting that the PTEN/Akt pathway is involved in the astroglial reaction in the rat hippocampus after transient forebrain ischemia.
authors.affiliation: Department of Anatomy, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul, 137-701, Korea. munylee@catholic.ac.kr
authors.forename: Jeong-Sun
authors.initials: JS
authors.lastname: Choi
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Park
authors.forename: Ha-Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Seong Yun
authors.initials: SY
authors.lastname: Kim
authors.forename: Ju Eun
authors.initials: JE
authors.lastname: Lee
authors.forename: Yun-Sik
authors.initials: YS
authors.lastname: Choi
authors.forename: Myung-Hoon
authors.initials: MH
authors.lastname: Chun
authors.forename: Jin-Woong
authors.initials: JW
authors.lastname: Chung
authors.forename: Mun-Yong
authors.initials: MY
authors.lastname: Lee
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D002546:Ischemic Attack, Transient / Q000378:metabolism*; D008297:Male; D051059:PTEN Phosphohydrolase; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D015415:Biomarkers; D005904:Glial Fibrillary Acidic Protein; D011518:Proto-Oncogene Proteins; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D017027:Protein Tyrosine Phosphatases; D051059:PTEN Phosphohydrolase; C487216:Pten protein, rat