Xenobiotic response element binding enriched in both nuclear and microsomal fractions of rat cerebellum.
Xenobiotic response element (XRE) is a core nucleotide sequence at the upstream of inducible target genes for the transcription factor aryl hydrocarbon receptor (AhR) that is responsible for signal transduction of exogenous environmental pollutants in eukaryotic cells. Immunoblotting analysis revealed the constitutive expression of AhR-related proteins in rat liver and brain, while specific binding of a radiolabelled probe containing XRE was detected in nuclear preparations of both liver and brain on gel retardation electrophoresis. Among discrete rat brain structures examined, cerebellum exhibited the highest XRE binding with less potent binding in hypothalamus, midbrain, medulla-oblongata, hippocampus, cerebral cortex and striatum. In contrast to liver and hippocampus, cerebellum also contained unusually higher XRE binding in microsomal fractions than that in either nuclear or mitochondrial fractions. Limited proteolysis by V8 protease did not markedly affect XRE binding in cerebellar nuclear extracts, with concomitant diminution of that in hepatic and hippocampal nuclear extracts. In primary cultured cerebellar neurons, indigo was effective in significantly increasing XRE binding only when determined immediately after sustained exposure for 120 min in the presence of high potassium chloride. These results suggest the abundance of as-yet unidentified proteins with high affinity for XRE and responsiveness to indigo in both nuclear and microsomal fractions of rat cerebellum.
Kuramoto
Nobuyuki
N
Laboratory of Molecular Pharmacology, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Ishikawa, Japan.
Baba
Katsuhiro
K
Gion
Keiko
K
Sugiyama
Chie
C
Taniura
Hideo
H
Yoneda
Yukio
Y
D000818:Animals; D001667:Binding, Competitive / Q000502:physiology; D001923:Brain Chemistry; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism*; D002478:Cells, Cultured; D002531:Cerebellum / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D007203:Indigo Carmine; D007211:Indoles / Q000494:pharmacology; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008861:Microsomes / Q000737:chemistry / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018336:Receptors, Aryl Hydrocarbon / Q000096:biosynthesis / Q000737:chemistry; D020218:Response Elements / Q000502:physiology*; D013347:Subcellular Fractions / Q000737:chemistry; D015262:Xenobiotics / Q000378:metabolism*
D007211:Indoles; D009687:Nuclear Proteins; D018336:Receptors, Aryl Hydrocarbon; D015262:Xenobiotics; D011189:Potassium Chloride; D007203:Indigo Carmine