Document Detail

Light-induced variations in AP-1 binding activity and composition in the rat suprachiasmatic nucleus.
MedLine Citation:
PMID:  9930761     Owner:  NLM     Status:  MEDLINE    
Expression of immediate early genes, including fos-like and jun-like genes, in the suprachiasmatic nucleus is believed to be part of the mechanism for photic entrainment of circadian rhythms to the environmental light/dark cycle. However, the effects of a light stimulus on activating protein-1 (AP-1) complexes in the suprachiasmatic nucleus remain unclear. The photic regulation of AP-1 DNA-binding activity and composition in the rat suprachiasmatic nucleus was evaluated by using an electrophoretic mobility shift assay. A light pulse given during subjective night induced an increase in AP-1 binding activity when either nuclear or whole-cell extracts from suprachiasmatic nuclei were used. Under constant dark conditions, proteins that are predominant components of AP-1 complexes are Fra-2 and Jun-D. Under light stimulation, c-Fos and Jun-B consistently increased, as expected, but this was also the case for Fra-2, Jun-D, and c-Jun, although to a lesser extent. An immunocytochemical study of the Fra-2 expression pattern demonstrated the presence of the protein in the ventrolateral as well as in the dorsomedial subdivisions of the suprachiasmatic nucleus. Light regulation of Fra-2 immunoreactivity, however, appeared to be restricted to the ventrolateral subdivision. It is concluded that light may be acting both by increasing constitutive AP-1 complexes and by inducing the expression of specific complexes.
A M François-Bellan; P Deprez; D Becquet
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of neurochemistry     Volume:  72     ISSN:  0022-3042     ISO Abbreviation:  J. Neurochem.     Publication Date:  1999 Feb 
Date Detail:
Created Date:  1999-02-11     Completed Date:  1999-02-11     Revised Date:  2005-11-17    
Medline Journal Info:
Nlm Unique ID:  2985190R     Medline TA:  J Neurochem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  841-7     Citation Subset:  IM    
Laboratoire des Interactions Fonctionnelles en Neuroendocrinologie, INSERM U501, Institut Fédératif Jean-Roche, Faculté de Médecine Nord, Marseille, France.
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MeSH Terms
Biological Clocks / physiology
DNA-Binding Proteins / analysis,  biosynthesis,  metabolism*
Fos-Related Antigen-2
Photic Stimulation
Protein Binding / physiology
Proto-Oncogene Proteins c-fos / biosynthesis
Rats, Sprague-Dawley
Suprachiasmatic Nucleus / chemistry*,  metabolism*
Transcription Factor AP-1 / analysis,  biosynthesis,  metabolism*
Transcription Factors / analysis
Visual Pathways / chemistry,  metabolism
Reg. No./Substance:
0/DNA-Binding Proteins; 0/Fos-Related Antigen-2; 0/Fosl2 protein, rat; 0/Proto-Oncogene Proteins c-fos; 0/Transcription Factor AP-1; 0/Transcription Factors

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