ABSTRACT In eukaryotes, protein de novo synthesis is mainly under the control at the level of gene transcription by transcription factors in cell nuclei. Transcription factors are nuclear proteins with affinities for particular core nucleotide element at the upstream of inducible target genes, followed by modulation of the activity of RNA polymerase II which is responsible for formation of mRNAs from double stranded DNAs. Gel retardation electrophoresis is widely employed for conventional detection of DNA binding activities of a variety of transcription factors with different protein motifs. In vivo administration of agonists at ionotropic excitatory amino acid (EAA) receptors leads to rapid and selective potentiation of DNA binding in the murine hippocampus of activator protein-1 (AP1) which is a dimmer between c-Jun and c-Fos protein families with leucine-zipper motifs. The potentiation is transient for N-methyl-D-aspartic acid but prolonged with kainic acid. Moreover, EAA signals indeed induce expression of both c-Jun and c-Fos proteins in the hippocampus in a manner unique to each other. Therefore, EAA signals may be differentially transduced into cell nuclei to express both c-Jun and c-Fos proteins and thereby modulate de novo synthesis of the individually different target genes at the level of gene transcription by AP1 in the murine hippocampus.
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