The cell-specific silencer region of the human dopamine beta-hydroxylase gene contains several negative regulatory elements.
Dopamine beta-hydroxylase (DBH) catalyzes the conversion of dopamine to noradrenaline and is selectively expressed in noradrenergic and adrenergic neurons in the nervous system. Transient transfection assays have indicated that cell-specific transcription of the human DBH gene may require a cell-specific silencer region residing at -486 to -263 bp upstream of the transcription start site. This region includes a putative DBH negative regulatory element (DNRE) with sequence homology to the restrictive element-1 (RE1)/neuron-restrictive silencer element identified in many other neural-specific genes. However, DNRE exerted negative regulation in both neuronal and nonneuronal cells alike, and site-directed mutation of this element did not significantly diminish the repressive activity of the DBH silencer region. Furthermore, expression of RE1-silencing transcription factor/neuron-restrictive silencer factor repressed neither DBH nor tyrosine hydroxylase promoter activity. We now report identification of three protein binding sites in the silencer region of the human DBH gene: SI at -271 to -250 bp, SII at -316 to -295 bp, and SIII at -348 to -324 bp. In vitro binding studies showed that SI and SIII, but not SII, interact with nuclear proteins from DBH-negative cells in a cell-specific manner. Furthermore, SI and SIII preferentially repressed the heterologous thymidine kinase and homologous DBH proximal promoter activities in nonneuronal cells. Taken together, the cell-specific silencer function of the upstream DBH region appears to involve several cis-regulatory elements, including two cell-specific repressor elements, SI and SIII, and a general negative regulatory element, DNRE. Based on these data, we propose that a highly restricted pattern of DBH gene expression in (nor)adrenergic cells of the nervous system may be controlled by multiple negative regulatory elements/silencers.
Kim
H S
HS
Department of Neurology, University of Tennessee, College of Medicine, Memphis 38163, USA.
Yang
C
C
Kim
K S
KS
D018983:DNA Footprinting; D004299:Dopamine beta-Hydroxylase / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D005816:Genetic Complementation Test; D006801:Humans; D009447:Neuroblastoma; D016385:TATA Box / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics; D014407:Tumor Cells, Cultured / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics
D014446:Tyrosine 3-Monooxygenase; D004299:Dopamine beta-Hydroxylase