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Molecular and Cellular Biology, December 1998, p. 6921-6929, Vol. 18, No. 12
Instituto de Neurobiología, Consejo
Superior de Investigaciones Científicas, 28002 Madrid,
Spain
Received 5 June 1998/Returned for modification 30 July
1998/Accepted 19 August 1998
Induction of the prodynorphin gene has been implicated in medium
and long-term adaptation during memory acquisition and pain. By 5'
deletion mapping and site-directed mutagenesis of the human prodynorphin promoter, we demonstrate that both basal transcription and
protein kinase A (PKA)-induced transcription in NB69 and SK-N-MC human
neuroblastoma cells are regulated by the GAGTCAAGG sequence centered at position +40 in the 5' untranslated region of the gene
(named the DRE, for downstream regulatory element). The DRE repressed
basal transcription in an orientation-independent and cell-specific
manner when placed downstream from the heterologous thymidine kinase
promoter. Southwestern blotting and UV cross-linking experiments with
nuclear extracts from human neuroblastoma cells or human brain revealed
a protein complex of approximately 110 kDa that specifically bound to
the DRE. Forskolin treatment reduced binding to the DRE, and the time
course paralleled that for an increase in prodynorphin gene expression.
Our results suggest that under basal conditions, expression of the
prodynorphin gene is repressed by occupancy of the DRE site. Upon PKA
stimulation, binding to the DRE is reduced and transcription increases.
We propose a model for human prodynorphin activation through
PKA-dependent derepression at the DRE site.
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Protein Kinase A-Dependent Derepression of the
Human Prodynorphin Gene via Differential Binding to an Intragenic
Silencer Element
*
Corresponding author. Mailing address: Instituto de
Neurobiología, C.S.I.C., Av. Dr. Arce 37, 28002 Madrid, Spain.
Phone: 34 1 585 4726. Fax: 34 1 585 4754. E-mail:
JRNARANJO{at}SAMBA.CNB.UAM.ES.
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