Identification of ATF-2 as a Transcriptional Regulator for the Tyrosine Hydroxylase Gene

Abstract

Transcriptional regulation of catecholamine-synthesizing genes is important for the determination of neurotransmitters during brain development. We found that three catecholamine-synthesizing genes were transcriptionally up-regulated in cloned PC12D cells overexpressing V-1, a protein that is highly expressed during postnatal brain development (1). To reveal the molecular mechanism to regulate the expression of tyrosine hydroxylase (TH), which is the rate-limiting enzyme for catecholamine biosynthesis, we analyzed the transcription factors responsible for TH induction in the V-1 clonal cells. First, by using reporter constructs, we found that the transcription mediated by cAMP-responsive element (CRE) was selectively enhanced in the V-1 cells, and TH promoter activity was totally dependent on the CRE in the promoter region of the TH gene. Next, immunoblot analyses and a transactivation assay using a GAL4 reporter system revealed that ATF-2, but not cAMP-responsive element-binding protein (CREB), was highly phosphorylated and activated in the V-1 cells, while both CREB and ATF-2 were bound to the TH-CRE. Finally, the enhanced TH promoter activity was competitively attenuated by expression of a plasmid containing the ATF-2 transactivation domain. These data demonstrated that activation of ATF-2 resulted in the increased transcription of the TH gene and suggest that ATF-2 may be deeply involved in the transcriptional regulation of catecholamine-synthesizing genes during neural development.Catecholamines are synthesized from L-tyrosine by the sequential action of four enzymes: tyrosine is converted to DOPA by tyrosine hydroxylase (TH), 1 DOPA to dopamine by aromatic L-amino acid decarboxylase (AADC), dopamine to norepinephrine by dopamine ␤-hydroxylase (DBH), and norepinephrine to epinephrine by phenylethanolamine N-methyltransferase. The regulation of the gene expression of these enzymes is important for the determination of the expression of neurotransmitters during brain development as well as for brain function under physiological and pathological conditions. TH is the rate-limiting enzyme for catecholamine biosynthesis. The transcriptional regulation of the TH gene has been extensively studied, and many transcription factors were suggested to regulate TH gene expression. CREB, ATF-1, and CREM were shown to recognize the cAMP-responsive element (CRE) located at position Ϫ45/Ϫ38 in the TH promoter (2-6). CREB was reported to mediate basal and cAMP-induced TH transcription in various cultured cells including PC12 cells by the use of dominant-negative CREB protein and antisense RNA against CREB (7-10). CREB is activated by phosphorylation on Ser 133 (11,12). The activation of CREB by phosphorylation has been shown to mediate PKA-dependent (7, 13-15) and -independent (13, 14) induction of TH transcription. Functional and physiological roles of ATF-1 and CREM for TH transcription remained unclear. AP-1 transcription factors bound to the TPA-responsive element located at Ϫ205/Ϫ199 in the TH promoter, which also plays ...

Nobiletin Induces Inhibitions of Ras Activity and Mitogen-Activated Protein Kinase Kinase/Extracellular Signal-Regulated Kinase Signaling to Suppress Cell Proliferation in C6 Rat Glioma Cells

“…Transfection and reporter gene assay were conducted as described previously. 23) phRG-TK was co-transfected with pCRE-luc with lipofectAMINE 2000, and used as an internal control to normalize for variations in transfection efficiency. Following 16-h transfection, cells were treated with the tested concentrations of nobiletin for 5 h. Thereafter, cells were harvested to assay the activities of both firefly and seapansy luciferase by using a dual luciferase assay kit.…”

ATF2, A Member of the CREB/ATF Family of Transcription Factors, in Chronic Stress and Consequent to Antidepressant Treatment: Animal Models and Human Post-Mortem Brains

“…Indeed, different groups of antidepressants have been shown to regulate the expression of a wide variety of genes (eg Ainsworth et al, 1998;Boyer et al, 1998;Vedder et al, 1999), demonstrating the involvement of additional transcription factors as intermediates between antidepressant-initiated intracellular cascades and gene regulation. ATF2 is a promising candidate, since it regulates two of the antidepressant-induced genes (Edelman et al, 2000;Suzuki et al, 2002), tyrosine hydroxylase (Nestler et al, 1990;Brady et al, 1992) and cell adhesion molecule L1 (Laifenfeld et al, 2002a). Moreover, the pathway upstream of ATF2, that is, the p38/MAPK pathway, is regulated by corticosterone on the one hand (Li, 2001), and the mood stabilizer, lithium, on the other (Chuang et al, 2002).…”

Prolonged Activation of cAMP-response Element-binding Protein and ATF-2 Needed for Nicotine-triggered Elevation of Tyrosine Hydroxylase Gene Transcription in PC12 Cells

“…ATF-1 was only marginally effective in increasing TH promoter activity, suggesting that it does not play a major role in the regulation of TH gene expression. ATF-2 has been implicated in transcriptional regulation of TH during neural development (21). Its expression in human brain is neuronal, and cell bodies of catecholamine-synthesizing neurons, such as the substantia nigra and locus coeruleus, are among the regions with especially high levels of ATF-2 expression (22).…”