Retinoic acid regulates ornithine decarboxylase gene expression at the transcriptional level.
Ontology highlight
ABSTRACT:
SUBMITTER: Mao Y
PROVIDER: S-EPMC1134606 | biostudies-other | 1993 Nov
REPOSITORIES: biostudies-other
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Project description:The mechanism of action of retinoic acid (RA) is of broad relevance to cell and developmental biology, nutrition, and cancer chemotherapy. RA is known to induce expression of the Burkitt's lymphoma receptor 1 (BLR1) gene which propels RA-induced cell cycle arrest and differentiation of HL-60 human myeloblastic leukemia cells, motivating the present analysis of transcriptional regulation of blr1 expression by RA. The RA-treated HL-60 cells used here expressed all RA receptor (RAR) and retinoid X receptor (RXR) subtypes (as detected by Northern analysis) except RXRgamma. Treatment with RAR- and RXR-selective ligands showed that RARalpha synergized with RXRalpha to transcriptionally activate blr1 expression. A 5'-flanking region capable of supporting RA-induced blr1 activation in HL-60 cells was found to contain a 205-bp sequence in the distal portion that was necessary for transcriptional activation by RA. Within this sequence DNase I footprinting revealed that RA induced binding of a nuclear protein complex to an element containing two GT boxes. Electromobility shift assays (EMSAs) and supershift assays showed that this element bound recombinant RARalpha and RXRalpha. Without RA there was neither complex binding nor transcriptional activation. Both GT boxes were needed for binding the complex, and mutation of either GT box caused the loss of transcriptional activation by RA. The ability of this cis-acting RAR-RXR binding element to activate transcription in response to RA also depended on downstream sequences where an octamer transcription factor 1 (Oct1) site and a nuclear factor of activated T cells (NFATc) site between this element and the transcriptional start, as well as a cyclic AMP response element binding factor (CREB) site between the transcriptional start and first exon of the blr1 gene, were necessary. Each of these sites bound its corresponding transcription factor. A transcription factor-transcription factor binding array analysis of nuclear lysate from RA-treated cells indicated several prominent RARalpha binding partners; among these, Oct1, NFATc3, and CREB2 were identified by competition EMSA and supershift and chromatin immunoprecipitation assays as components of the complex. RA upregulated expression of these three factors. In sum the results of the present study indicate that RA-induced expression of blr1 expression depends on a novel RA response element. This cis-acting element approximately 1 kb upstream of the transcriptional start consists of two GT boxes that bind RAR and RXR in a nuclear protein complex that also contains Oct1, NFATc3, and CREB2 bound to their cognate downstream consensus binding sites.
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Project description:Protein arginine methyltransferase 3 (PRMT3) regulates protein functions by introducing asymmetric dimethylation marks at the arginine residues in proteins. However, very little is known about the interaction partners of PRMT3 and their functional outcomes. Using yeast-two hybrid screening, we identified Retinal dehydrogenase 1 (ALDH1A1) as a potential interaction partner of PRMT3 and confirmed this interaction using different methods. ALDH1A1 regulates variety of cellular processes by catalyzing the conversion of retinaldehyde to retinoic acid. By molecular docking and site-directed mutagenesis, we identified the specific residues in the catalytic domain of PRMT3 that facilitate interaction with the C-terminal region of ALDH1A1. PRMT3 inhibits the enzymatic activity of ALDH1A1 and negatively regulates the expression of retinoic acid responsive genes in a methyltransferase activity independent manner. Our findings show that in addition to regulating protein functions by introducing methylation modifications, PRMT3 could also regulate global gene expression through protein-protein interactions.
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Project description:Pontin is a AAA+ ATPase protein that has functions in various biological contexts including gene transcription regulation, chromatin remodeling, DNA damage sensing and repair, as well as assembly of protein and ribonucleoprotein complexes. Pontin is known to regulate the transcription of several important signaling pathways, including Wnt signaling. However, its role in early embryonic signaling regulation remains unclear. Retinoic acid (RA) signaling plays a central role in vertebrate development. Using an in vivo biotin tagging technology, we mapped the genome-wide binding pattern of Pontin before and after RA-induced differentiation in the pluripotent embryo carcinoma cell line NTERA-2. Biotin ChIP-seq revealed significant changes in genome-wide Pontin binding sites upon RA stimulation. We also identified a substantial amount of overlapping binding peaks between Pontin and RARα, especially on all of the HOX gene loci (A-D clusters). Pontin knockdown experiments showed that its chromatin binding at the HOX gene clusters is required for RA-induced HOX gene expression. Furthermore, we performed Global Run-On sequencing (GRO-seq) to map de novo transcripts genome-wide and found that Pontin knockdown significantly diminished nascent HOX gene transcripts, indicating that Pontin regulates HOX gene expression at the transcriptional level. Finally, proteomic analysis demonstrated that Pontin associates with chromatin organization/remodeling complexes and various other functional complexes. Altogether, we have demonstrated that Pontin is a critical transcriptional co-activator for RA-induced HOX gene activation.
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Project description:Ornithine decarboxylase (ODC) is the sentinel enzyme in polyamine biosynthesis. Both ODC and polyamines regulate cell division, proliferation, and apoptosis. Sepiapterin reductase (SPR) catalyzes the last step in the biosynthesis of tetrahydrobiopterin (BH4), an essential cofactor of nitric oxide synthase, and has been implicated in neurological diseases but not yet in cancer. In this study, we present compelling evidence that native ODC and SPR physically interact, and we defined the individual amino acid residues involved in both enzymes using in silico protein-protein docking simulations. The resulting heterocomplex is a surprisingly compact structure, featuring two energetically and structurally equivalent binding modes both in monomer and in dimer conformations. The novel interaction between ODC and SPR proteins was confirmed under physiological conditions by co-immunoprecipitation and co-localization in neuroblastoma (NB) cells. Importantly, we showed that siRNA (small interfering RNA)-mediated knockdown of SPR expression significantly reduced endogenous ODC enzyme activity in NB cells, thus demonstrating the biological relevance of the ODC-SPR interaction. Finally, in a cohort of 88 human NB tumors, we found that high SPR mRNA expression correlated significantly with poor survival prognosis using a Kaplan-Meier analysis (log-rank test, P=5 × 10(-4)), suggesting an oncogenic role for SPR in NB tumorigenesis. In conclusion, we showed that ODC binds SPR and thus propose a new concept in which two well-characterized biochemical pathways converge via the interaction of two enzymes. We identified SPR as a novel regulator of ODC enzyme activity and, based on clinical evidence, present a model in which SPR drives ODC-mediated malignant progression in NB.
| S-EPMC4013099 | biostudies-literature
Project description:Macrophage activation is a critical step in host responses during bacterial infections. Ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine metabolism, has been well studied in epithelial cells and is known to have essential roles in many different cellular functions. However, its role in regulating macrophage function during bacterial infections is not well characterized. We demonstrate that macrophage-derived ODC is a critical regulator of M1 macrophage activation during both Helicobacter pylori and Citrobacter rodentium infection. Myeloid-specific Odc deletion significantly increased gastric and colonic inflammation, respectively, and enhanced M1 activation. Add-back of putrescine, the product of ODC, reversed the increased macrophage activation, indicating that ODC and putrescine are regulators of macrophage function. Odc-deficient macrophages had increased histone 3, lysine 4 (H3K4) monomethylation, and H3K9 acetylation, accompanied by decreased H3K9 di/trimethylation both in vivo and ex vivo in primary macrophages. These alterations in chromatin structure directly resulted in up-regulated gene transcription, especially M1 gene expression. Thus, ODC in macrophages tempers antimicrobial, M1 macrophage responses during bacterial infections through histone modifications and altered euchromatin formation, leading to the persistence and pathogenesis of these organisms.
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Project description:We have studied the regulation of the expression of ornithine decarboxylase with the aid of transgenic mice harbouring either functional human ornithine decarboxylase genes or the mouse ornithine decarboxylase promoter-driven chloramphenicol acetyltransferase fusion gene in their genome. We used three different stimuli which are well known to enhance ornithine decarboxylase activity in their appropriate target tissues: (i) testosterone in female kidney, (ii) a phorbol ester in epidermis and (iii) partial hepatectomy in liver. Endogenous mouse ornithine decarboxylase activity was strikingly stimulated in response to these treatments. Even though containing the 5' flanking region of the mouse ornithine decarboxylase gene, known to possess full promoter activity, the chloramphenicol acetyltransferase reporter gene was entirely insensitive to any of these stimuli. The human transgene-derived ornithine decarboxylase activity in kidney was unaffected by testosterone treatment, but responded in skin to application of the phorbol ester and likewise was clearly enhanced in regenerating liver. Although mouse endogenous ornithine decarboxylase mRNA levels were distinctly elevated after testosterone, this treatment did not influence the accumulation of the human transgene-derived mRNA. The phorbol ester enhanced the accumulation of mouse endogenous ornithine decarboxylase mRNA and also that derived from the human transgene; however, the enzyme activity was stimulated in regenerating liver without appreciable changes in the levels of endogenous or transgene-derived message. Our present results strongly emphasize the central role of the coding sequence or ornithine decarboxylase gene in the induction of the enzyme activity.
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Project description:NRL (neural retina leucine zipper) is a key basic motif-leucine zipper (bZIP) transcription factor, which orchestrates rod photoreceptor differentiation by activating the expression of rod-specific genes. The deletion of Nrl in mice results in functional cones that are derived from rod precursors. However, signaling pathways modulating the expression or activity of NRL have not been elucidated. Here, we show that retinoic acid (RA), a diffusible factor implicated in rod development, activates the expression of NRL in serum-deprived Y79 human retinoblastoma cells and in primary cultures of rat and porcine photoreceptors. The effect of RA is mimicked by TTNPB, a RA receptor agonist, and requires new protein synthesis. DNaseI footprinting and electrophoretic mobility shift assays (EMSA) using bovine retinal nuclear extract demonstrate that RA response elements (RAREs) identified within the Nrl promoter bind to RA receptors. Furthermore, in transiently transfected Y79 and HEK293 cells the activity of Nrl-promoter driving a luciferase reporter gene is induced by RA, and this activation is mediated by RAREs. Our data suggest that signaling by RA via RA receptors regulates the expression of NRL, providing a framework for delineating early steps in photoreceptor cell fate determination.
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Project description:BACKGROUND:Dietary arginine and meat consumption are implicated in colorectal cancer (CRC) progression via polyamine-dependent processes. Polymorphism in the polyamine-regulatory gene, ornithine decarboxylase 1 (Odc1, rs2302615) is prognostic for CRC-specific mortality. Here, we examined joint effects of meat consumption and Odc1 polymorphism on CRC-specific mortality. MATERIALS AND METHODS:The analytic cohort was comprised of 329 incident stage I-III CRC cases diagnosed 1994-1996 with follow- up through March 2008. Odc1 genotyping was conducted using primers that amplify a 172-bp fragment containing the polymorphic base at +316. Dietary questionnaires were administered at cohort entry. Multivariate Cox proportional hazards regression analysis for CRC-specific mortality was stratified by tumor, node, metastasis (TNM) stage, and adjusted for clinically relevant variables, plus meat consumption (as a continuous variable, i.e., the number of medium-sized servings/week), Odc1 genotype, and a term representing the meat consumption and Odc1 genotype interaction. The primary outcome was the interaction of Odc1 and meat intake on CRC-specific mortality, as assessed by departures from multiplicative joint effects. RESULTS:Odc1 genotype distribution was 51% GG, 49% GA/AA. In the multivariate model, there was a significant interaction between meat consumption and Odc1 genotype, P-int = 0.01. Among Odc1 GA/AA CRC cases in meat consumption Quartiles 1-3, increased mortality risk was observed when compared to GG cases (adjusted hazards ratio (HR) = 7.06 [95% CI 2.34-21.28]) - a difference not found among cases in the highest dietary meat consumption Quartile 4. CONCLUSIONS:Effects of meat consumption on CRC-specific mortality risk differ based on genetic polymorphism at Odc1. These results provide further evidence that polyamine metabolism and its modulation by dietary factors such as meat may have relevance to CRC outcomes.
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Project description:Retinoic acid receptors (RARs) are members of the nuclear hormone receptor family and regulate the proliferation and differentiation of multiple different cell types, including promyelocytic leukemia cells. Here we describe a biochemical/functional interaction between the Ca(2+)/calmodulin-dependent protein kinases (CaMKs) and RARs that modulates the differentiation of myeloid leukemia cells. We observe that CaMKIIgamma is the CaMK that is predominantly expressed in myeloid cells. CaMKII inhibits RAR transcriptional activity, and this enzyme directly interacts with RAR through a CaMKII LxxLL binding motif. CaMKIIgamma phosphorylates RARalpha both in vitro and in vivo, and this phosphorylation inhibits RARalpha activity by enhancing its interaction with transcriptional corepressors. In myeloid cell lines, CaMKIIgamma localizes to RAR target sites within myeloid gene promoters but dissociates from the promoter upon retinoic acid-induced myeloid cell differentiation. KN62, a pharmacological inhibitor of the CaMKs, enhances the terminal differentiation of myeloid leukemia cell lines, and this is associated with a reduction in activated (autophosphorylated) CaMKII in the terminally differentiating cells. These observations reveal a significant cross-talk between Ca(2+) and retinoic acid signaling pathways that regulates the differentiation of myeloid leukemia cells, and they suggest that CaMKIIgamma may provide a new therapeutic target for the treatment of certain human myeloid leukemias.
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Project description:How organisms adapt to unfavorable environmental conditions by means of plasticity or selection of favorable genetic variants is a central issue in evolutionary biology. In the Maipo River basin, the fish Basilichthys microlepidotus inhabits polluted and non-polluted areas. Previous studies have suggested that directional selection drives genomic divergence between these areas in 4% of Amplified Fragment Length Polymorphism (AFLP) loci, but the underlying genes and functions remain unknown. We hypothesized that B. microlepidotus in this basin has plastic and/or genetic responses to these conditions. Using RNA-Seq, we identified differentially expressed genes in individuals from two polluted sites compared with fish inhabiting non-polluted sites. In one polluted site, the main upregulated genes were related to cellular proliferation as well as suppression and progression of tumors, while biological processes and molecular functions involved in apoptotic processes were overrepresented in the upregulated genes of the second polluted site. The ornithine decarboxylase gene (related to tumor promotion and progression), which was overexpressed in both polluted sites, was sequenced, and a parallel pattern of a heterozygote deficiency and increase of the same homozygote genotype in both polluted sites compared with fish inhabiting the non-polluted sites was detected. These results suggest the occurrence of both a plastic response in gene expression and an interplay between phenotypic change and genotypic selection in the face of anthropogenic pollution.
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