Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.1.17 (ornithine decarboxylase)
 6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transcription of the ornithine decarboxylase (ODC) gene is rapidly elevated by activation of protein kinase A (PKA). The additive influence of three cis-acting elements is responsible for this regulation in an adrenal carcinoma cell line. Two sites, CRE2 at -48 base pairs (bp) relative to the start of transcription and CRE3 at +95 bp, are identical to the core motif of the cAMP-responsive element (CRE) of the somatostatin gene and are conserved in the mouse, rat, and human ODC genes. Mutation of CRE2 resulted in a substantial decrease in basal promoter activity, as well as a 5-fold decrease in inducibility of the ODC promoter by PKA. CRE3 did not contribute to the basal activity of the ODC promoter, but mutation of this site resulted in a 2-fold decrease in inducibility by PKA. Deletion of a 45-bp sequence (GC-box) located 5' of CRE2, also resulted in a 2-fold decrease in inducibility of the ODC promoter. DNase I protection revealed the presence of protein binding at CRE2, the TATA box, and the GC-box of the ODC promoter. Mutation of CRE2 resulted in loss of protection of this sequence, as well as the 3' extension of the footprint over the TATA box, without affecting interactions at the GC box. Antibodies to the well characterized CRE-binding protein CREB recognized proteins binding to CRE2, suggesting that binding of CREB, or an antigenically related protein, is important for the activity of CRE2. Additionally, recombinant CREB bound to a DNA probe containing the CRE2 sequence.
 ...
PMID:Multiple DNA elements responsible for transcriptional regulation of the ornithine decarboxylase gene by protein kinase A. 135 8

We have characterized a DNA-protein interaction within a sequence element distal from the site of transcription initiation within the mouse housekeeping gene (HPRT) promoter region. This interaction occurs within a 35-base pair regulatory element which confers cell type-specific gene transcription, designated as the HPRT cis-acting regulatory element (HCRE). Competition analysis by gel mobility shift electrophoresis indicates that this DNA-protein interaction is novel and not related to many transcription factors previously reported. Cell cycle synchronization experiments and gel mobility shift assays have demonstrated that within the HCRE a specific DNA-protein complex responds to G1 activation of the cell cycle. Experiments to purify specific DNA-binding proteins that interact with the HCRE has resulted in the purification of one sequence-specific DNA-binding protein of approximately 66 kDa. To determine the putative DNA-binding sequence, footprinting analysis has mapped the protection from DNase I hydrolysis which confers a core sequence of GTCTGGGT using both affinity purified protein and crude nuclear extract. This DNA motif represents a novel protein-binding sequence. Interestingly, data base searches have identified the same or homologous sequences of this DNA motif in additional genes, potentially related to cellular growth and proliferation. This consensus was most notable within a region 5' upstream of the ornithine decarboxylase gene. The unique cell type-specific regulation of the HPRT gene in the intestinal mucosa is not completely understood at this time but because of the relationship of ornithine decarboxylase expression to cell proliferation and more specifically, to mucosal cell renewal in the intestine, the function of DNA-protein interactions within the consensus sequence may prove analogous. This may account for the cell type-specific and cell-cycle responsive gene regulation previously demonstrated with HPRT. Identification of one sequence-specific DNA-binding protein within the HCRE suggest that this protein contributes to the trans-activation of specific genes during the immediate-early response of the cell cycle.
 ...
PMID:Characterization of DNA-protein interactions within a distal regulatory element upstream of a mammalian housekeeping gene promoter. 155 10

To evaluate the function of the murine ornithine decarboxylase (ODC) gene promoter, expression of chimeric ODC-chloramphenicol acetyltransferase (CAT) plasmids (pODCcat) containing 1,658 nt of the ODC promoter sequence and its various 5'-deletions was analyzed. In transient expression assays with NIH/3T3 mouse cells, pODCcat constructs exhibited fairly strong promoter activity yielding CAT values up to 40% of those obtained with the viral promoter RSV. Interestingly, 5'-deletions of the pODCcat constructs increased the promoter activity over that achieved using the entire 1.6-kb 5'-flanking region, with the highest activity being observed with about 750 nt of the ODC promoter. This finding suggests that the distal part of the promoter includes DNA elements which are involved in repressing its function. The promoter region could be deleted down to the proximal 97 nt and still be stimulated by cAMP to the same extent as the 1.6-kb promoter. DNase I footprinting and methylation interference studies showed that a specific protein binds to the region from -59 to -39, which encompasses a DNA motif resembling the consensus cyclic AMP response element (CRE). However, comparative gel retardation and Southwestern blotting experiments with the putative ODC-CRE and the somatostatin promoter CRE indicated that the 70-kDa protein interacting with the CRE-like element of the ODC promoter is different from the well-characterized nuclear CRE-binding protein CREB.
 ...
PMID:Protein-DNA interactions in the cAMP responsive promoter region of the murine ornithine decarboxylase gene. 165 Apr 55

Treatment of calf thyroid slices with TSH increases the nuclease sensitivity of nuclear chromatin, i.e. the amount of DNA released from nuclei by mild digestion with DNase I and micrococcal nuclease. Cycloheximide and alpha-amanitin were used to investigate the roles played by protein and RNA synthesis in mediating this effect of TSH; alpha-difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase, was used to investigate the possible involvement of polyamines. Calf thyroid slices were incubated with or without TSH (50 mU/ml) for 5 h, in the presence or absence of inhibitors. Nuclei were then prepared, subjected to mild digestion with micrococcal nuclease, and centrifuged at 1200 X g. The amount of DNA in 1200 X g supernatants was increased by TSH; this was inhibited by cycloheximide (100 micrograms/ml) and alpha-amanitin (4 micrograms/ml) when these agents were present throughout incubations with TSH. In contrast, alpha-amanitin failed to inhibit the TSH effect when it was added to incubations 30 min or 2 h after the addition of TSH. These results indicate that RNA and protein synthesis play a part in mediating the effect of TSH on the micrococcal nuclease sensitivity of chromatin, and that the RNA synthesis involved takes place within the first 30 min of exposure of thyroid slices to TSH. alpha-Difluoromethylornithine (5 mM) inhibited the TSH-dependent development of micrococcal nuclease sensitivity; however, it also inhibited nuclease digestion when it was added directly to nuclei prepared from fresh thyroid tissue. This observation should serve as a warning against uncritical acceptance of the notion that all effects of alpha-difluoromethylornithine are the result of inhibition of ornithine decarboxylase.
 ...
PMID:Effects of cycloheximide, alpha-amanitin, and alpha-difluoromethylornithine on thyrotropin-induced increases in the micrococcal nuclease sensitivity of thyroid nuclear chromatin. 643 5

The early response gene ornithine decarboxylase (odc) is indispensable for normal and malignant cell growth. Although DNA methylation is generally associated with chromatin condensation and gene inactivation, the odc gene is heavily methylated at CCGG-sequences in animal cell lines. In this work we analyzed the chromatin structure and the DNA methylation status at the CpG-rich promoter sequences at the odc locus in mouse 3T3 fibroblasts. We show that the proximal promoter region of the odc locus is not hypermethylated, while the distal promoter sequences appear to have a few methylated CCGG-sites and display methylation polymorphism. Furthermore, it was found that the 5' promoter region of odc is constitutively more sensitive to micrococcal nuclease than the coding and 3' regions of the odc gene. Stimulation of the cells with serum resulted in an appearance of a DNase I sensitive site at the promoter region. The chromatin structure of the mid-coding and 3' regions of the odc gene also underwent structural changes that were accompanied by the rapid accumulation of odc mRNA. Such changes were not detected in the chromatin structure of glyceraldehyde-3-phosphate dehydrogenase (gadph) gene, whose expression remains invariant upon serum stimulation. These data suggest that the chromatin structure may play an important role in the rapid transcriptional activation of odc and other immediate early genes during serum stimulation.
 ...
PMID:Methylation status and chromatin structure of an early response gene (ornithine decarboxylase) in resting and stimulated NIH-3T3 fibroblasts. 752 36

Ornithine decarboxylase (ODC) is the rate-limiting enzyme of polyamine biosynthesis. We investigated the transcriptional regulation of the rat ODC gene using transient expression assays. The 5'-flanking region (-1156 to +13) of the ODC gene was sufficient to mediate strong basal expression of a luciferase reporter. Sequences between -345 and -93 contributed to basal promoter activity. This region, containing five potential Sp1 binding sites, was analyzed by electrophoretic mobility shift assays. Three specific DNA-protein complexes were identified using H35 nuclear extracts and the -345/-93 ODC probe. Binding to all three was eliminated by competition with an oligonucleotide containing an Sp1 binding site, but not by a mutant Sp1 oligonucleotide. Preincubation with an antibody against Sp1 supershifted complexes associated with one or more of Sp1 binding sites 1-4 as well as with site 5. DNase I footprinting revealed two protected regions: PR-I (-92 to -130) and PR-II (-304 to -332). PR-I contains a putative binding site for Sp1 that was protected by recombinant Sp1 protein. Transfection studies in Schneider SL2 cells demonstrated that the ODC promoter is transactivated up to 350-fold by Sp1 and that this transactivation is dependent on the presence of Sp1 binding sites 1-4. Thus, although the ODC promoter binds multiple nuclear proteins, Sp1 or a related protein appears to be a critical determinant of ODC transcription, possibly through cooperative interactions between Sp1 and additional transcription factors.
 ...
PMID:Regulation of rat ornithine decarboxylase promoter activity by binding of transcription factor Sp1. 787 96

Regulation of ornithine decarboxylase (ODC) is critical to the control of cellular growth, differentiation, and carcinogenesis. A GC-rich region in the ODC promoter contains two overlapping protein binding sites that interact to regulate basal level expression in some cell types. A perfect binding motif for transcription factor Sp1 (CCCCGCCCC) is located at nucleotides -114 to -106 relative to the site of transcriptional initiation, binds strongly to purified Sp1 protein, and forms several complexes when incubated with nuclear extracts. Only one of these complexes is recognized by Sp1-specific antibody. A new protein-binding motif (GCCCCTCCCC, located at -110 to -100) partially overlaps with the Sp1 site and analyses by DNase I protection showed that a new protein ("NF-ODC1") and the Sp1-like proteins interact with the ODC promoter in a mutually exclusive manner. Mutation of the NF-ODC1 binding motif strongly enhanced ODC promoter strength in some cell types, but had little or no influence in others. The effect of mutating the Sp1 site also varied with cell type. These cell type specificities did not correlate with the levels of Sp1 and NF-ODC1 binding activities in nuclear extracts. These results show that regulation of the ODC promoter by the Sp1 family is cell type-specific and modulated by a negative effector that we have termed NF-ODC1.
 ...
PMID:Complex interactions at a GC-rich domain regulate cell type-dependent activity of the ornithine decarboxylase promoter. 813 14

The importance of ornithine decarboxylase (ODC) to cell proliferation is underscored by the complex array of cell-specific mechanisms invoked to regulate its synthesis and activity. Misregulation of ODC has severe negative consequences on normal cell function, including the acquisition of tumorigenic growth properties by cells overexpressing ODC. We hypothesize that ODC gene expression is a candidate target for the anti-proliferative function of certain tumor suppressors. Here we show that the Wilms' tumor suppressor WT1 binds to multiple sites within the human ODC promoter, as determined by DNase I protection and methylation interference assays. The expression of WT1 in transfected HCT 116, NIH/3T3 and HepG2 cells represses activity of the ODC promoter controlling expression of a luciferase reporter gene. In contrast WT1 expression enhances ODC promoter activity in SV40-transfected HepG2 cells. Both the extent of modulation of ODC gene expression and the mediating WT1 binding elements are cell specific. Constructs expressing WT1 deletion mutants implicate two regions required for repressor function, as well as an intrinsic activation domain. Understanding the regulation of ODC gene expression by WT1 may provide valuable insights into the roles of both WT1 and ODC in development and tumorigenesis.
 ...
PMID:Regulation of ornithine decarboxylase gene expression by the Wilms' tumor suppressor WT1. 860 51

Ornithine decarboxylase (ODC) expression is important for proliferation and is elevated in many tumor cells. We previously showed that Sp1 is a major positive regulator of ODC transcription. In this paper we have investigated transcriptional regulation of rat ODC by the closely related factor Sp3. While over-expression of Sp1 caused a dramatic activation of the ODC promoter, over-expression of Sp3 caused little or no activation in either Drosophila SL2 cells (lacking endogenous Sp1 or Sp3) or in H35 rat hepatoma cells. Furthermore, co-transfection studies demonstrated that Sp3 abolished trans -activation of the ODC promoter by Sp1. DNase I footprint studies and electrophoretic mobility shift assays demonstrated that both recombinant Sp1 and Sp3 bind specifically to several sites within the ODC promoter also protected by nuclear extracts, including overlapping GC and CT motifs located between -116 and -104. This CT element is a site of negative ODC regulation. Mutation of either element reduced binding, but mutation of both sites was required to eliminate binding of either Sp1 or Sp3. These results demonstrate that ODC is positively regulated by Sp1 and negatively regulated by Sp3, suggesting that the ratio of these transcription factors may be an important determinant of ODC expression during development or transformation.
 ...
PMID:Transcription factor Sp3 antagonizes activation of the ornithine decarboxylase promoter by Sp1. 911 70