title: Basal expression, subcellular distribution, and up-regulation of the proto-oncogene c-JUN in the rat dentate gyrus after unilateral entorhinal cortex lesion.
abstract: The expression of the transcription factor c-JUN was investigated in the rat fascia dentata under normal conditions and after entorhinal cortex lesion. As shown by immunocytochemistry and in situ hybridization histochemistry c-JUN and its messenger RNA are present in the principal cell layers of the dentate gyrus and Ammon's horn (except hippocampal region CA2). Pre-embedding immunogold electron microscopy revealed an almost exclusive nuclear localization of c-JUN, where it is associated with chromatin. In addition, double immunolabelling for c-JUN and parvalbumin demonstrated that c-JUN immunoreactivity is primarily found in principal neurons since GABAergic parvalbumin-positive interneurons did not express c-JUN. After unilateral electrolytic lesion of the entorhinal cortex c-JUN was strongly up-regulated in the ipsilateral dentate gyrus within 2 h postlesion. This up-regulation was also present in the contralateral fascia dentata 12 h after entorhinal cortex lesion and returned to control levels on both sides 24 h postlesion. The cellular distribution of c-JUN did not change after entorhinal cortex lesion: parvalbumin-positive interneurons never contained c-JUN. These results point to a specific role of c-JUN in the granule cells of the fascia dentata in the normal animal and in rats with entorhinal cortex lesions. The selective induction of c-JUN after entorhinal lesion could be one of the first molecular steps that regulate transneuronal changes within granule cells after their denervation. A different mechanism has to be assumed for GABAergic interneurons known to receive an entorhinal innervation as well.
authors.affiliation: Institute of Anatomy, University of Freiburg, Germany.
authors.forename: C A
authors.initials: CA
authors.lastname: Haas
authors.forename: T
authors.initials: T
authors.lastname: Deller
authors.forename: M
authors.initials: M
authors.lastname: Frotscher
mesh_terms: D000818:Animals; D003714:Denervation; D018891:Dentate Gyrus / Q000737:chemistry / Q000378:metabolism*; D018728:Entorhinal Cortex / Q000166:cytology / Q000601:surgery*; D005786:Gene Expression Regulation / Q000502:physiology; D007395:Interneurons / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D009473:Neuronal Plasticity / Q000502:physiology; D010320:Parvalbumins / Q000032:analysis; D016755:Proto-Oncogene Proteins c-jun / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D010320:Parvalbumins; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger