Sequences downstream of the transcription initiation site are important for proper initiation and regulation of mouse ribonucleotide reductase R2 gene transcription

Kotova, Irina; Chabes, Andrei; Lobov, Sergei; Thelander, Lars; Björklund, Stefan

doi:10.1046/j.1432-1033.2003.03541.x

Cited by 8 publications

(9 citation statements)

References 35 publications

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“…It is well established that the M1-M2 complex provides deoxynucleotide triphosphate pools for normal DNA replication in proliferating cells (26). This enzyme activity is tightly regulated by the cell cycle -specific availability of the M2 subunit, whereas the M1 protein level remains relatively constant throughout the cell cycle (27). It has been proposed that repair of DNA damage is dependent on the M1-p53R2 holoenzyme rather than on the M1-M2 enzyme (11,16,18).…”

Section: Discussionmentioning

confidence: 99%

Impairment of the DNA Repair and Growth Arrest Pathways by p53R2 Silencing Enhances DNA Damage–Induced Apoptosis in a p53-Dependent Manner in Prostate Cancer Cells

Devlin¹,

Mack²,

Burich³

et al. 2008

Molecular Cancer Research

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Abstractp53R2 is a p53-inducible ribonucleotide reductase that contributes to DNA repair by supplying deoxynucleotide triphosphate pools in response to DNA damage. In this study, we found that p53R2 was overexpressed in prostate tumor cell lines compared with immortalized prostatic epithelial cells and that the protein was induced upon DNA damage. We investigated the effects of p53R2 silencing on DNA damage in LNCaP cells (wild-type p53). Silencing p53R2 potentiated the apoptotic effects of ionizing radiation and doxorubicin treatment as shown by increased sub-G 1 content and decreased colony formation. This sensitizing effect was specific to DNA-damaging agents. Comet assay and ;-H2AX phosphorylation status showed that the decreased p53R2 levels inhibited DNA repair. Silencing p53R2 also reduced the levels of p21 WAF1/CIP1 at the posttranscriptional level, suggesting links between the p53-dependent DNA repair and cell cycle arrest pathways. Using LNCaP sublines stably expressing dominant-negative mutant p53, we found that the sensitizing effect of p53R2 silencing is mediated by p53-dependent apoptosis pathways. In the LNCaP sublines (R273H, R248W, and G245S) that have defects in inducing p53-dependent apoptosis, p53R2 silencing did not potentiate DNA damage -induced apoptosis, whereas p53R2 silencing was effective in a LNCaP subline (P151S) which retains the ability to induce p53-dependent apoptosis. This study shows that p53R2 is a potential therapeutic target that could be used to enhance the effectiveness of ionizing radiation or DNA-damaging chemotherapy in a subset of patients with prostate cancer. (Mol Cancer Res 2008;6(5):808 -18)

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Section: Discussionmentioning

confidence: 99%

Impairment of the DNA Repair and Growth Arrest Pathways by p53R2 Silencing Enhances DNA Damage–Induced Apoptosis in a p53-Dependent Manner in Prostate Cancer Cells

Devlin¹,

Mack²,

Burich³

et al. 2008

Molecular Cancer Research

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“…Conservation of a stability element at the 5Ј end of p742 transcripts would allow both classes of transcripts to be upregulated by the same mechanism. However, the location of essential DRE1 elements downstream of the core promoter does not exclude the possibility that the relevant elements are DNA elements, as transcription factor binding sites downstream of initiation sties are hardly rare, especially in multiple-start promoters (8,9,13,14,17,24,29,33,38,63).…”

Section: Discussionmentioning

confidence: 99%

Genetic Analysis of the Human Papillomavirus Type 31 Differentiation-Dependent Late Promoter

Bodily

Meyers

2005

J Virol

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Human papillomaviruses infect stratifying squamous epithelia, causing benign and malignant lesions. Upon differentiation of the host keratinocyte, the virus undergoes a dramatic increase in both DNA replication and transcription from the late promoter, leading to expression of late genes and virion morphogenesis. In human papillomavirus type 31 (HPV31), the late promoter is designated p742 and includes multiple start sites embedded within the E7 gene. In this report, we mapped viral DNA elements that control transcriptional activity from p742. Enhancer elements in the viral upstream regulatory region positively regulate this promoter. The region containing the transcriptional start sites is dispensable for activity, and at least two separate elements in the E6/E7 region are capable of supporting transcription. Of these, we mapped one to a 150-bp region of the E7 open reading frame and designate it the core p742 promoter. Using GF109203X, an inhibitor of protein kinase C signaling, we show that p742 activation is independent of viral genome amplification. Finally, we mapped elements in the region of p742 that confer responsiveness to differentiation and show that the upstream regulatory region does not contribute to the differentiation response of p742. These studies are an important step toward understanding the functioning and regulation of this multiple-start promoter.

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Section: Ribonucleotide Reductase (Rnr)mentioning

confidence: 99%

“…Neither mutation affects the cell cycle-specific expression pattern. In the absence of the TTTAAA box, R2 transcription is directed by sequences downstream of the transcription start site interacting with TAF II s (15,16).Together with a number of other S phase-specific genes such as DNA polymerase-␣ and thymidylate synthase, the R2 gene was activated when quiescent cells were infected with an E2F1- …”

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confidence: 99%

S Phase-specific Transcription of the Mouse Ribonucleotide Reductase R2 Gene Requires Both a Proximal Repressive E2F-binding Site and an Upstream Promoter Activating Region

Chabes¹,

Björklund

Thelander

2004

Journal of Biological Chemistry

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Ribonucleotide reductase is essential for supplying a balanced pool of the four deoxyribonucleotides required for DNA synthesis and repair. The active enzyme consists of two non-identical subunits called proteins R1 and R2. There are multiple levels of regulation of ribonucleotide reductase activity, which is highest during the S and G 2 phases of an unperturbed cell cycle in mammalian cells. Previous reports in the literature have indicated that the S phase-specific transcription of the mammalian R2 gene is regulated by a transcriptional block, is dependent on the transcription factor E2F1, or is simply regulated by proteins that bind to promoter CCAAT boxes plus the TATA box. Here, we demonstrate that the S phase-specific transcription of the mouse R2 gene is dependent on an upstream promoter activating region (located at nucleotides (nt) ؊672 to ؊527 from the transcription start site) and one proximal promoter repressive element (located at nt ؊112 to ؊107) that binds E2F4. Binding to the E2F site is modulated by binding of nuclear factor-Y to an adjacent CCAAT element (nt ؊79 to ؊75). The upstream activating region is crucial for overall R2 promoter activity. Mutation of the E2F-binding site leads to premature promoter activation in G 1 and increases overall promoter activity but only when the upstream activating region is present and intact. Therefore, E2F-dependent repression is essential for cell cycle-specific R2 transcription. Ribonucleotide reductase (RNR)1 is essential for de novo synthesis of deoxyribonucleotides (dNTPs), which are required for DNA replication and repair (1). The RNR-catalyzed reduction of ribonucleotides is the rate-limiting step in DNA precursor biosynthesis. Synthesis of deoxyribonucleotides is an extremely well regulated reaction. A failure in the control of the dNTP levels and/or their relative amounts leads to cell death or genetic abnormalities (2, 3). Most eukaryotic RNRs are composed of two non-identical homodimeric subunits, a large subunit (R1) and a small subunit (R2), which are both required for activity. The R1 subunit contains the catalytic site and, in addition, allosteric sites that control both enzyme activity and specificity by binding nucleoside triphosphates. The R2 subunit contains a non-heme iron center, which generates a tyrosyl free radical essential for catalysis.In human and mouse cells, the genes encoding the R1 and R2 proteins are situated on different chromosomes (4, 5). The transcription of the R1 and R2 genes is cell cycle-regulated, with undetectable mRNA levels in G 0 /G 1 phase cells and maximal levels in S phase cells (6). The R1 protein has a long half-life, and its levels are almost constant and in excess in proliferating cells (7). Enzyme activity is therefore determined by R2 protein levels. The R2 protein is stable during S phase and is degraded in late mitosis. The degradation depends on a KEN box sequence recognized by the Cdh1⅐anaphase-promoting complex active in late mitosis and during G 0 /G 1 (8). The R2 protein is stabilized after DNA d...

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Sequences downstream of the transcription initiation site are important for proper initiation and regulation of mouse ribonucleotide reductase R2 gene transcription

Cited by 8 publications

References 35 publications

Impairment of the DNA Repair and Growth Arrest Pathways by p53R2 Silencing Enhances DNA Damage–Induced Apoptosis in a p53-Dependent Manner in Prostate Cancer Cells

Impairment of the DNA Repair and Growth Arrest Pathways by p53R2 Silencing Enhances DNA Damage–Induced Apoptosis in a p53-Dependent Manner in Prostate Cancer Cells

Genetic Analysis of the Human Papillomavirus Type 31 Differentiation-Dependent Late Promoter

S Phase-specific Transcription of the Mouse Ribonucleotide Reductase R2 Gene Requires Both a Proximal Repressive E2F-binding Site and an Upstream Promoter Activating Region

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