title: Constitutive expression of cytoplasmic activator protein-1 with DNA binding activity and responsiveness to ionotropic glutamate signals in the murine hippocampus.
abstract: Gel retardation electrophoresis revealed that cytosolic fractions contained DNA binding activity of the transcription factor activator protein-1 with profiles different from those reported in nuclear extracts in murine brain. In particular, activator protein-1 DNA binding was almost undetectable at 25 degrees C in the presence of both KCl and MgCl2 in cytosol fractions. Moreover, cytoplasmic activator protein-1 binding occurred at three different mobilities on the gel when determined at 2 degrees C in the absence of MgCl2. Systemic administration of N-methyl-D-aspartate and kainate led to marked potentiation of cytoplasmic activator protein-1 binding detected as slow bands in the murine hippocampus, without markedly affecting that as a fast band. Immunoblotting and supershift assays revealed much higher expression of both immunoreactive c-Jun and c-Fos in hippocampal cytosolic fractions in response to the administration of kainate than N-methyl-D-aspartate. These results suggest that activator protein-1 may be constitutively expressed in the cytoplasm with DNA binding activity and responsiveness to ionotropic glutamate signals in a manner different from that in the nucleus in the murine hippocampus.
authors.affiliation: Department of Pharmacology, Setsunan University, Hirakata, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Azuma
authors.forename: K
authors.initials: K
authors.lastname: Ogita
authors.forename: Y
authors.initials: Y
authors.lastname: Yoneda
mesh_terms: D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D001798:Blood Proteins / Q000096:biosynthesis*; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis* / Q000378:metabolism; D015342:DNA Probes; D003720:Densitometry; D004591:Electrophoresis, Polyacrylamide Gel; D006624:Hippocampus / Q000378:metabolism* / Q000648:ultrastructure; D015151:Immunoblotting; D007376:Interleukin-2 / Q000096:biosynthesis*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D017470:Receptors, Glutamate / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D001798:Blood Proteins; D015342:DNA Probes; D007376:Interleukin-2; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D017470:Receptors, Glutamate; C021001:cytoplasmic activator protein, human; D004247:DNA