Regulation of tyrosine hydroxylase gene expression by retinoic acid receptor

Abstract

Retinoic acid (RA), a derivative of vitamin A, critically controls brain patterning and neurogenesis during embryogenesis, and is known to regulate morphological differentiation of catecholaminergic neuronal cells. In this study, we investigated whether the retinoic acid receptor (RAR), a transcription factor specifically activated by all-trans-RA, could directly regulate transcription of tyrosine hydroxylase (TH), the first and ratelimiting step in the catecholamine biosynthesis pathway. First, treating TH-expressing human neuroblastoma SK-N-BE(2)C cells with all-trans RA resulted in an approximately 1.7-fold increase in endogenous TH mRNA expression, as determined by real-time PCR analysis. Second, when SK-N-BE(2)C cells were transiently co-transfected with the TH promoter-luciferase reporter construct, reporter gene expression was prominently activated by RAR in a ligand-dependent manner. Third, we identified a putative RAR responsive cis-regulatory element at ) 1500 to ) 1487 bp in the TH upstream promoter region by deletional and site-directed mutational analysis. Finally, we demonstrated that this putative motif directly interacts with RAR protein in a sequence-specific manner by means of an electrophoretic mobility shift assay. Taken together, our results indicate that the TH gene may be a direct downstream target of the RA signaling pathway and that RAR is able to activate TH transcription through interaction with an upstream sequence motif residing at ) 1500 to ) 1487 bp.

Differential and Interactive Effects of Ligand-Bound Progesterone Receptor A and B Isoforms on Tyrosine Hydroxylase Promoter Activity.

“…When PR-B was overexpressed, progesterone treatment effectively increased TH promoter activity in both TH expressing (CAD and SK-N-SH) and non-TH expressing (CV-1) cells, suggesting PR-B actions are not dependent on cell type. These data contrast with nuclear receptor related 1 protein (NURR1) and retinoic acid receptor actions on the TH promoter, which do show cell type specificity (24,42). After progesterone treatment, both PR-A and PR-B predominantly localized in the cell nucleus of CAD cells, supporting their roles as nuclear transcription factors.…”

“…The complexity of transcriptional control is substantiated by the multiple DNA regulatory elements in the 5' region upstream of the transcription start site (19). Some steroid hormones, including glucocortocoids, oestrogens, androgens, and retinoic acid, acting through their respective receptors, influence TH promoter activity (21)(22)(23)(24), although little is known about progesterone action on the TH promoter.…”

Epigenetic mechanisms in the development and maintenance of dopaminergic neurons

“…RA-induced activation of RA-responsive elements might also affect the expression of mdDA-specific genes, such as tyrosine hydroxylase (Th; discussed below). Such a direct role for RARs in transcriptional regulation of the Th gene was suggested in SK-N-BE(2)C cells, in which RAR bound the promoter of the Th gene and induced Th expression upon activation of RAR by RA (Jeong et al, 2006) (Fig. 2D).…”

Retinoic acid-dependent and -independent gene-regulatory pathways of Pitx3 in meso-diencephalic dopaminergic neurons

“…We were able to mimic the RA-mediated rescue of Th transcript in Pitx3-deficient embryos by administration of a pan-RAR-agonist, and RAR transcript levels were upregulated in Pitx3-deficient embryos after treatment of the pregnant mothers with RA (data not shown). In vitro, a direct role for RARs in transcriptional regulation of the Th gene was suggested in SK-N-BE(2)C cells, where RARb bound the promoter of Th and induced Th expression upon activation of RARb by at-RA (Jeong et al, 2006).…”