Induction of Krüppel-like factor 4 expression in reactive astrocytes following ischemic injury in vitro and in vivo.
Krüppel-like factor 4 (KLF4) is a transcription factor with diverse and cell type-specific functions and is associated with a variety of pathophysiological processes. Recently, it has been proposed that the regulation of KLF4 is critical to neuronal differentiation and that neural progenitors overexpressing KLF4 take on a glial identity. The present study aimed to determine whether KLF4 is involved in the astroglial reaction induced by ischemia-reperfusion injury in the brain. No specific KLF4 immunoreactivity was observed in resting astrocytes of the control hippocampus, but significant induction was detected in reactive astrocytes preferentially located in the CA1 and dentate hilar regions of the hippocampus following transient forebrain ischemia. Astroglial KLF4 expression was induced in the nuclei and cytoplasm within 3 days of ischemia and persisted for at least 4 weeks. This pattern was reproduced in an in vitro astrogliosis model of rat primary cortical astrocytes exposed to oxygen-glucose deprivation (OGD). Furthermore, immunoblot assay showed that nuclear and cytosolic extracts from cortical astrocytes subjected to OGD had significantly higher levels of KLF4 protein compared to normoxic extracts. Thus, our data demonstrate that KLF4 expression was induced in astroglia by ischemic injury both in vivo and in vitro, suggesting that KLF4 may act as a transcription factor linked to the regulation of the astroglial reaction following ischemic injury.
Department of Anatomy, Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Seocho-gu, Seoul, 137-701, Korea.
Joo-Hee
JH
Park
Tae-Ryong
TR
Riew
Yoo-Jin
YJ
Shin
Jang-Mi
JM
Park
Jeong Min
JM
Cho
Mun-Yong
MY
Lee
D000818:Animals; D001253:Astrocytes / Q000473:pathology*; D056547:CA1 Region, Hippocampal / Q000473:pathology; D015687:Cell Hypoxia; D002478:Cells, Cultured; D018891:Dentate Gyrus / Q000473:pathology; D005947:Glucose / Q000172:deficiency; D020925:Hypoxia-Ischemia, Brain / Q000473:pathology*; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley
C000715469:Klf4 protein, rat; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D012333:RNA, Messenger; D005947:Glucose