Repeated Immobilization Stress Increases the Binding of c-Fos-Like Proteins to a Rat Dopamine β-Hydroxylase Promoter Enhancer Sequence

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Abstract
Repeated immobilization stress elicits a large elevation in adrenal dopamine beta-hydroxylase (DBH) mRNA levels. This study attempts to analyze the molecular mechanism of increased DBH gene expression in stress. Adrenomedullary nuclear proteins were prepared from controls and rats exposed to various intervals of immobilization stress. Electrophoretic mobility shift assays showed that repeated stress led to increased binding of adrenomedullary nuclear factors to a cis-acting regulatory element in the rat DBH promoter (DBH-1). One of the partners in the DNA-protein complex is c-Fos or a Fos-related protein. There was a correlation between promoter binding activity and elevated steady-state levels of DBH mRNA. Our data indicate that this cis regulatory element in the rat DBH promoter is functional in vivo, and increased binding of AP1-like transcription factors to this motif is induced by immobilization stress.