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Induction of 72‐kDa Inducible Heat Shock Protein (HSP72) in Cultured Rat Astrocytes After Energy Depletion
Author(s) -
Imuta Naohiko,
Ogawa Satoshi,
Maeda Yusuke,
Kuwabara Keisuke,
Hori Osamu,
Ueda Hirokazu,
Yanagihara Takehiko,
Tohyama Masaya
Publication year - 1998
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1998.70020550.x
Subject(s) - heat shock protein , biology , microbiology and biotechnology , protein biosynthesis , cycloheximide , transfection , stress granule , astrocyte , reporter gene , hsp70 , biochemistry , gene expression , messenger rna , gene , translation (biology) , endocrinology , central nervous system
Abstract: Protein synthesis is important in the readaptive processes for cultured astrocytes after hypoxia and subsequent reoxygenation. We have identified 72‐kDa inducible heat shock protein (HSP72) as a major stress protein in reoxygenated astrocytes. To assess the mechanism for reoxygenation‐mediated induction of HSP72, a reporter gene that consists of a human HSP promoter fused to the luciferase gene was transfected into cultured astrocytes. Analysis of cellular energy nucleotides showed an increase of the ADP/ATP ratio after reoxygenation, which synchronized with activation of the HSP promoter. Activation of the HSP promoter was also observed after an addition of iodoacetic acid to hypoxic astrocytes, which reached the maximum when the ADP/ATP ratio reached 50%, but further decline in the energy profile caused inactivation of this promoter. Inhibition of protein synthesis after reoxygenation resulted in temporary restoration of the energy profile and suppression of the DNA binding activity of the heat shock factor. Addition of quercetin greatly decreased the [ 3 H]leucine incorporation in the polysome fraction without any effect on the mature mRNA formation. These data suggest that the energy depletion in reoxygenation triggers induction of HSP72 after reoxygenation, which may act as a pivotal mediator in the stress response of reoxygenated astrocytes by facilitating protein synthesis.