Constitutive expression of cytoplasmic activator protein-1 with DNA binding activity and responsiveness to ionotropic glutamate signals in the murine hippocampus.
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.
Azuma
Y
Y
Department of Pharmacology, Setsunan University, Hirakata, Osaka, Japan.
Ogita
K
K
Yoneda
Y
Y
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*
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