Regulation of the tyrosine hydroxylase and dopamine beta-hydroxylase genes by the transcription factor AP-2.
The retinoic acid-inducible and developmentally regulated transcription factor AP-2 plays an important role during development. In adult mammals, AP-2 is expressed in both neural and non-neural tissues. However, the function of AP-2 in different neuronal phenotypes is poorly understood. In this study, transcriptional regulation of tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) genes by AP-2 was investigated. AP-2 binding sites were identified in the upstream regions of both genes. Electrophoretic mobility shift assays (EMSA) and DNase I footprinting analyses indicate that the AP-2 interaction with these motifs is more prominent in catecholaminergic SK-N-BE(2)C and CATH.a than in non-catecholaminergic HeLa and HepG2 cell lines. Exogenous expression of AP-2 robustly transactivated TH and DBH promoter activities in non-catecholaminergic cell lines. While AP-2 regulates the DBH promoter activity via a single site, transactivation of the TH promoter by AP-2 appears to require multiple sites. In support of this, mutation of multiple AP-2 binding sites but not that of single site diminished the basal promoter activity of the TH gene in cell lines that express TH and abolished transactivation by exogenous AP-2 expression in cell lines that do not express TH. In contrast, mutation of a single AP-2 binding site of the DBH gene completely abolished transactivation by AP-2. Double-label immunohistochemistry showed that AP-2 is coexpressed with TH in noradrenergic and adrenergic neurons in both the central and peripheral nervous systems of adult rodents. Numerous non-catecholaminergic cell groups within the spinal cord, medulla, cerebellum, and pons also express AP-2. The concentration of AP-2 in dorsomedial locations along the neuraxis suggests a regionally specific role for this transcription factor in the regulation of neuronal function. Based on these findings we propose that AP-2 may coregulate TH and DBH gene expression and thus participate in expression/maintenance of neurotransmitter phenotypes in (nor)adrenergic neurons and neuroendocrine cells.
Kim
H S
HS
Department of Neurology, University of Tennessee, College of Medicine, Memphis, Tennessee, USA.
Hong
S J
SJ
LeDoux
M S
MS
Kim
K S
KS
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002395:Catecholamines / Q000378:metabolism; D002460:Cell Line; D002490:Central Nervous System / Q000166:cytology / Q000201:enzymology; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004299:Dopamine beta-Hydroxylase / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009474:Neurons / Q000166:cytology / Q000201:enzymology*; D009928:Organ Specificity; D017933:Peripheral Nervous System / Q000166:cytology / Q000201:enzymology; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics; D014162:Transfection; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism*
D002395:Catecholamines; D004268:DNA-Binding Proteins; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D014446:Tyrosine 3-Monooxygenase; D004299:Dopamine beta-Hydroxylase