Dopamine receptor regulating factor, DRRF: A zinc finger transcription factor

Abstract

Dopamine receptor genes are under complex transcription control, determining their unique regional distribution in the brain. We describe here a zinc finger type transcription factor, designated dopamine receptor regulating factor (DRRF), which binds to GC and GT boxes in the D 1A and D2 dopamine receptor promoters and effectively displaces Sp1 and Sp3 from these sequences. Consequently, DRRF can modulate the activity of these dopamine receptor promoters. Highest DRRF mRNA levels are found in brain with a specific regional distribution including olfactory bulb and tubercle, nucleus accumbens, striatum, hippocampus, amygdala, and frontal cortex. Many of these brain regions also express abundant levels of various dopamine receptors. In vivo, DRRF itself can be regulated by manipulations of dopaminergic transmission. Mice treated with drugs that increase extracellular striatal dopamine levels (cocaine), block dopamine receptors (haloperidol), or destroy dopamine terminals (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) show significant alterations in DRRF mRNA. The latter observations provide a basis for dopamine receptor regulation after these manipulations. We conclude that DRRF is important for modulating dopaminergic transmission in the brain.T ranscriptional regulation in eukaryotes is governed by the coordinated action of regulatory factors that bind to specific DNA elements. One class of these factors comprises zinc finger proteins of which Sp1 is a prototypical example, having three Cys-2-His-2 zinc finger motifs (1). Other family members, Sp2, Sp3, and Sp4, with similar structural and functional features also have been identified (2, 3). Sp1, Sp3, and Sp4 bind to the same recognition sequence (GC boxes) with similar affinities (3, 4). While Sp1 and Sp4 generally act as transcription activators, Sp3 can act as repressor or activator (5). Sp2, on the other hand, has a DNA-binding specificity different (2) from that of Sp1, Sp3, or Sp4. Several additional factors with the same zinc finger motif as Sp1 have been cloned and found to bind to the GC box sequence (6-8).Central dopaminergic neurotransmission is crucial for normal brain function, and its aberrations are intricately involved in several neuropsychiatric disorders. The specific biological effects of dopamine are determined at least in part by the complex spatial and temporal regulation of genes encoding its receptors. and D 2 genes have revealed a delicate balance among several nuclear factors that tightly regulate expression of these genes (10-12). For example, the D 2 gene promoter is under strong negative control (13). One of its silencing elements (nucleotides Ϫ116 to Ϫ76), which consists of an Sp1 consensus sequence (GC box) and three TGGG repeats (GT box), interacts with Sp1, Sp3 (10), and an unidentified factor (13). In the present investigation, we characterized the nature and function of this nuclear protein, which regulates the expression of dopamine receptor genes.

Activation of the rat dopamine D2 receptor promoter by mitogen‐activated protein kinase and Ca2+/calmodulin‐dependent protein kinase II pathways

“…9ai). Consistent with the previous report (Hwang et al 2001), overexpression of DRRF-HA suppressed D2R promoter activity in a dosedependent manner (Fig. 9aii).…”

“…The silencing elements were defined as D2NegA (from )160 to )135) and D2NegB (from )116 to )76), and D2NegB contains the TGGG repeat and Sp1 site A (Minowa et al 1994). Gel shift analysis of this region revealed that Sp1, Sp3 and DRRF bind to the D2NegB site (Hwang et al 2001). However, negative regulatory effects of these regions were observed only in NB43A3 cells, and not in NB2A cells and MMQ cells in the present and the previous studies by Valdenaire et al (1994), respectively.…”

“…Effect of DRRF on the D2R promoter activity in NB2A cell Hwang et al (2001) recently identified DRRF, a zinc finger transcription factor, as a negative regulator of the D2R promoter. We examined effects of DRRF on both basal activity and MEKK or Zif268-induced potentiation of D2R promoter activity.…”

“…It has also been reported that the D2R promoter is under strong negative control by two silencing elements (D2Neg A, from nucleotides )217 to )160, and D2Neg B, from nucleotides )116 to )76) in D2R-expressing NB41A3 cells (Minowa et al 1992 and. D2Neg B consists of an Sp1 consensus sequence (Sp1 site A) and three TGGG repeats (GT box), which also interact with Sp1 (Minowa et al 1994), Sp3 (Yajima et al 1998) and a zinc finger type transcription factor such as dopamine receptor regulating factor (DRRF) in the D2R promoter (Hwang et al 2001). On the other hand, Valdenaire et al (1994) reported that there are no silencing elements in the D2R promoter in D2R-expressing MMQ cells and that the negative regulation by the silencing elements depends on the cell type used.…”

“…They and other groups suggest the existence of a strong positive element in the D2R promoter between nucleotides )75 and )30, which contains an Sp1 consensus sequence (Sp1 site B) (Minowa et al 1992;Valdenaire et al 1994). Transcription factors, such as Sp1, Sp3 and DRRF, bind to the proximal ciselements in vitro and, among them, Sp3 and DRRF inhibit D2R promoter activity (Minowa et al 1994;Chernak et al 1997;Yajima et al 1998;Hwang et al 2001). Whilst increase in the D2R promoter activity by treatment with retinoic acid (RA) was reported in transfected COS-1 cells (Samad et al 1997) and C6 glioma cells (Valdenaire et al 1998), RA-response elements from nucleotides )68 to )55 were indicated as responsible for its activation (Samad et al 1997;Valdenaire et al 1998).…”