Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was undertaken to evaluate p53 gene mutation as a prognostic factor in patients with colorectal cancer. Nonisotopic RNase cleavage assay (NIRCA), recently used for detecting gene mutations, was employed to detect p53 gene mutations in this study. In 15 samples of colorectal tumors, NIRCA was confirmed to be simple, accurate, and thus useful for clinical use, compared with polymerase chain reaction single-strand conformational polymorphism (PCR-SSCP). In another group of 79 cases of colorectal cancer analyzed for p53 gene mutation by using NIRCA, mutations were detected in 58 of 79 (73.4%) cases. Multivariate Cox proportional-hazards analysis showed that p53 gene mutation was a significant prognostic factor in patients with colorectal cancer. Our results showed that NIRCA is a simple and sensitive method, and thus useful for genetic screening of colorectal cancer. Furthermore, our results showed that p53 gene mutation is an independent predictor of poor prognosis in colorectal cancers.
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PMID:Detection of p53 gene mutations by nonisotopic RNase cleavage assay as a predictor of poor prognosis in colorectal cancers. 1462 45

Adenoviral p53 gene transfer (Ad-p53) induces apoptosis in glioma cells expressing mutant p53, but fails in cells with wild-type p53. Endogenously, gliomas express varied levels of Fas/CD95, yet constitutively high levels of Fas/CD95 ligand. Because the mechanism behind the differential apoptotic response to Ad-p53 infection remains elusive, we examined how the Fas/CD95 pathway is involved in U87MG (wt-p53), D54 (wt-p53), U251MG (mutant-p53), and U373MG (mutant-p53) glioma cell lines. Ad-p53 infection did not alter the levels of Fas/CD95 ligand in either wild-type or mutant p53-expressing cell lines. In contrast, Ad-p53 infection led to an approximately 3-fold increase in Fas/CD95 mRNA expression in mutant p53-bearing cell lines but not in their wild-type (wt) counterparts, as assessed in an RNase protection assay. Fas/CD95 mRNA induction appeared to be regulated at the transcriptional level because Ad-p53 infection resulted in up to a 4-fold increase in Fas/CD95 promoter reporter activity. Subsequently, flow cytometric analysis revealed a 2- to 4-fold increase in surface Fas/CD95 expression following Ad-p53 infection in mutant-p53-containing cell lines. Use of the protein transport inhibitor Brefeldin A significantly inhibited Ad-p53-induced surface Fas/CD95 expression, but only partially inhibited apoptosis in mutant-p53 cell lines. These results suggest that p53 regulates Fas/CD95 expression at the transcriptional level and through protein trafficking in mutant-p53 cell lines. Fluorogenic activity assays demonstrated that induction of caspase-8 activity following Ad-p53 infection correlated with increases in Fas/CD95 expression. Incubating cells with a caspase-8-specific inhibitor Ac-IETD-CHO prior to Ad-p53 infection inhibited caspase-8 activity and apoptosis. Together, our results suggest that regulation of the Fas/CD95 pathway is partly responsible for Ad-p53-induced apoptosis in glioma cells, which depends on the p53 status of the involved cells. Additionally, the inability of Ad-p53 to activate the Fas/CD95 pathway in wt-p53 glioma cells coincides with their apoptotic-resistant phenotype. Further elucidation of the nature of this resistance could ultimately augment the efficacy of Ad-p53 gene therapy.
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PMID:Differential activation of the Fas/CD95 pathway by Ad-p53 in human gliomas. 1471 18

Nuclear DNA helicase II (NDH II), alternatively named RNA helicase A (RHA), is an F-actin binding protein that is particularly enriched in the nucleolus of mouse cells. Here, we show that the nucleolar localization of NDH II of murine 3T3 cells depended on an ongoing rRNA synthesis. NDH II migrated out of the nucleolus after administration of 0.05 microg/ml actinomycin D, while nucleolin and the upstream binding factor (UBF) remained there. In S phase-arrested mouse cells, NDH II was frequently found at the nucleolar periphery, where it was accompanied by newly synthesized nucleolar RNA. Human NDH II was mainly distributed through the whole nucleoplasm and not enriched in the nucleoli. However, in the human breast carcinoma cell line MCF-7, NDH II was also found at the nucleolar periphery, together with the tumor suppressor protein p53. Both NDH II and p53 were apparently attached to the F-actin-based filamentous network that surrounded the nucleoli. Accordingly, this subnuclear structure was sensitive to F-actin depolymerizing agents. Depolymerization with gelsolin led to a striking accumulation of NDH II in the nucleoli of MCF-7 cells. This effect was abolished by RNase, which extensively released nucleolus-bound NDH II when added together with gelsolin. Taken together, these results support the idea that an actin-based filamentous network may anchor NDH II at the nucleolar periphery for pre-ribosomal RNA processing, ribosome assembly, and/or transport.
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PMID:Nuclear DNA helicase II (RNA helicase A) binds to an F-actin containing shell that surrounds the nucleolus. 1472 62

Cell proliferation and apoptosis are controlled by tightly orchestrated signaling pathways that culminate in transcriptional activation/repression of multiple proteins. Dysregulation of cell cycle and/or apoptosis control may lead to genomic instability, neoplastic transformation and tumor progression. Under certain conditions, some hexavalent chromium [Cr(VI)] compounds are toxic and carcinogenic in the human respiratory tract, and we have shown that they induce apoptosis and/or cell cycle arrest in a p53-dependent fashion. There is increasing evidence linking extracellular signal-regulated kinase (ERK) activation with the DNA damage response, by both p53-dependent and -independent mechanisms. Here, the aim was to study the effect of Cr(VI) transcriptional regulation of key cell cycle inhibitors and pro- and anti-apoptotic proteins, as well as the role of ERK activation in the Cr(VI) genotoxic response. Diploid human lung fibroblasts were incubated with 3-9 uM Na2CrO4, and RNA was isolated at 4, 8, and 24 h, as well as 24 h after Cr(VI) exposure was terminated (recovery). mRNA expression was quantitated by RNase protection assay with a 32P-labeled multi-transcript probe containing gene sequences for the cdk inhibitors, p21waf1/cip1, p27kip1, p16INK4a, p15INK4b; the pro-apoptotic proteins bcl-XS and bax; the anti-apoptotic proteins bcl-W, bcl-XL, and bcl2, GADD45, and cyclin A. In general, bcl-W and bcl-XL expression were both downregulated after Cr exposure, to around 50% at 24 h, which was more pronounced after the recovery period. At Cr(VI) concentrations < or = 6 uM, bcl2 expression was upregulated. Of particular interest is that bax expression was reduced, in a dose and time-dependent fashion, however that of bcl-XS was elevated by nearly 3-fold after 8 h, and declined to control levels at the end of the recovery period. Expression of GADD45 and p21 were both upregulated by 2-fold at 8 h, but declined to control levels during recovery. Neither the expression of p27 nor that of p16 were apparently affected by Cr(VI) exposure, however the expression of p15 was markedly increased after exposure to all concentrations of Cr(VI). Finally, the expression of cyclin A was decreased after 24 h Cr(VI) exposure. Cr(VI) induced a transient burst of ERK activity (2-6-fold over control) around 0.5-3 h after exposure. However, inhibition of ERK activation with PD98059 had no effect on the Cr-induced alterations in gene expression. Moreover, Cr(VI)-induced clonogenic lethality, as assessed after 24 h exposure to 1 and 2 uM Cr(VI), was also not affected by ERK inhibition. These data suggest that both p53-dependent and -independent apoptotic and growth-inhibitory pathways are markedly affected by Cr(VI) exposure. However, the ability of Cr(VI) to affect key apoptotic and growth arresting genes, and thus clonogenic lethality, appears to be independent of ERK. Continued investigation into the cellular and molecular mechanisms of Cr(VI)-induced cell cycle and apoptosis control should further the understanding of Cr(VI)-associated carcinogenesis.
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PMID:Induction of pro-apoptotic and cell cycle-inhibiting genes in chromium (VI)-treated human lung fibroblasts: lack of effect of ERK. 1497 55

Human hepatoma cell lines undergo apoptosis after treatment with cisplatin (CP), by mechanisms that are not fully understood, although our previous study demonstrated that Fas-dependent or -independent pathways are involved. To elucidate the mechanisms of CP-induced apoptosis in Hep3B cells, which are Fas- and p53-negative, we investigated mitochondria associated pathways, the involvement of NF-kappaB, and p73 activation. Results of Western blot and flow cytometry assay revealed that the translocation of Bax, resulted in the loss of mitochondrial membrane potential (Deltaphi(m)) and the efflux of cytochrome c and of second mitochondria-derived activator of caspase/DIABLO from mitochondria into the cytosol. Caspase-3, -8 and -9 were activated by CP treatment, however, CP-induced apoptosis was not completely blocked by pretreating with the pan-caspase inhibitor, benzyloxycarbonyl-valinyl-alaninyl-aspartyl-(O-methyl)-fluoromethylketone, indicating that caspase-independent apoptotic pathways might also be involved. RNase protection assay confirmed that NF-kappaB downregulation leading to the suppression of its target genes, such as XIAP and TRAF2, and p73 accumulation were also observed in Hep3B cells treated with CP. CP-induced apoptosis was inhibited to some extent by transiently overexpressed p73 dominant negative and XIAP, but not by p73DN or XIAP alone. In conclusion, this study demonstrates that CP-induced apoptosis in Hep3B cells is associated with mitochondrial dysregulation, NF-kappaB downregulation and p73 accumulation.
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PMID:Cisplatin-induced apoptosis in Hep3B cells: mitochondria-dependent and -independent pathways. 1504 63

The C-terminus of p53 is responsible for maintaining the latent, non-DNA-binding form of p53. However, the mechanism by which the C-terminus regulates DNA binding is not yet fully understood. We show here that p53 interacts with RNA via its C-terminal domain and that disruption of this interaction, by RNase A treatment, truncation or phosphorylation of the C-terminus, restores DNA-binding activity. Furthermore, the oligomerization of p53 is significantly enhanced by disrupting the interaction between p53 and RNA. These findings suggest that binding of RNA to p53 is involved in the mechanism of p53 latency.
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PMID:Binding of RNA to p53 regulates its oligomerization and DNA-binding activity. 1506 27

We have previously shown that mouse Dda3 gene is a p53 and p73 transcriptional target whose expression suppresses tumor cell growth. Here, we report the identification of multiple variants of Dda3 transcripts with diverse 5' sequences through 5'] rapid amplification of cDNA ends (5'-RACE) and RT-PCR. Analysis by primer extension and RNase protection revealed that the 5'-heterogeneity was generated by transcription initiation at multiple sites in exon 1 and intron 1 and by alternative splicing. These transcripts, both coding and non-coding, exhibited distinct expression patterns in various adult tissues and were developmentally regulated. Furthermore, they were induced in a p53-dependent manner by various stress signals. These data demonstrated that differential initiation of transcription and alternative splicing both participate in the regulation of Dda3 gene expression.
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PMID:5'-Heterogeneity of mouse Dda3 transcripts is attributed to differential initiation of transcription and alternative splicing. 1511 Nov 31

Protein B23/nucleophosmin is a multifunctional protein that plays roles in ribosome biogenesis, control of centrosome duplication, and regulation of p53 expression. A yeast two-hybrid screen was performed in a search for interaction partners of B23. The complementary DNA for a highly acidic protein, nucleoplasmin 3 (NPM3), was found in multiple positive clones. Protein NPM3 and its interaction with B23 were further characterized. Endogenous B23 was able to be co-immunoprecipitated with NPM3, and this complex was resistant to ribonuclease treatment and high concentrations of salt. The N-terminal 35-90 amino acids of B23 were found to be required for their interaction. Separate co-immunoprecipitation studies of B23 and NPM3 suggested the existence of two different complexes, one containing B23 and 28 S ribosomal RNA (rRNA) and another composed of B23, NPM3, and other proteins, but no RNA. NPM3 was localized in the nucleolus, and its nucleolar localization depended on active rRNA transcription. In the cells overexpressing NPM3, there were decreased rates of pre-rRNA synthesis and processing. Overexpression of a mutant of NPM3 that did not interact with B23 did not alter pre-rRNA synthesis and processing, suggesting that the interaction of NPM3 with B23 plays a role in the ribosome biogenesis.
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PMID:Protein NPM3 interacts with the multifunctional nucleolar protein B23/nucleophosmin and inhibits ribosome biogenesis. 1559 47

In vitro expansion of chondrocytes for tissue-engineering applications is limited by forms of growth arrest known as quiescence and replicative senescence. At the molecular level cyclin-dependent kinase inhibitors (CDKIs) are involved in mediating growth arrest in the G1 phase of the cell cycle. Using ribonuclease protection assays and immunocytochemical staining methods, we quantitatively analyzed expression profiles of G1 cell cycle inhibitors at the mRNA and protein levels. These inhibitors included the CDKIs of the CIP/KIP family (p21CIP1 p27KIP1, and p57KIP2) and the INK4 family (p15INK4b, p16INK4a, p18INK4c, and p19INK4d) as well as the retinoblastoma protein-family (pRb, p107, and p130) and the tumor suppressor p53. Analysis was carried out in proliferating, quiescent, and senescent states of primary cultures of adult human nasoseptal chondrocytes. The most pronounced effect (p < 0.0001) between cultures in proliferation and cultures in growth arrest was an increased expression of the CDKIs p57KIP2 and p15INK4b for quiescent growth arrest, and of p16INK4a, p15INK4b, and p57KIP2 for senescent growth arrest. Thus, these cell cycle inhibitors represent potential candidates for selective intervention to promote cellular multiplication of chondrocytes undergoing in vitro expansion for tissue-engineering applications. Possible methods of modulation include the targeted elimination of specifically identified cell cycle inhibitors by antisense technologies.
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PMID:In vitro expansion of human nasoseptal chondrocytes reveals distinct expression profiles of G1 cell cycle inhibitors for replicative, quiescent, and senescent culture stages. 1573 62

Human monocytic THP-1 cells can be induced to differentiate to macrophages when treated with phorbol 12-myristate 13-acetate (PMA). It is understood that before initiating cell differentiation, PMA treatment must first induce an inhibition of cell growth. Since the initial biochemical and molecular events that are associated with this growth inhibition have not been characterized, the present study was carried out to elucidate the molecular mechanisms associated with the PMA-induced growth arrest of THP-1 cells. Our results indicate that PMA inhibits THP-1 cells at G1-phase of the cell cycle, via a complex mechanism associated with the modulation of the expression of several cell cycle regulators, initiated by the cellular generation of reactive oxygen species (ROS). Both p21WAF1/CIP1 mRNA and protein were upregulated 24 h post PMA treatment as demonstrated by ribonuclease protection assay and Western blotting, respectively. Because these cells lack functional p53, this effect was independent of p53 activity. Electrophoretic mobility shift assay showed that the PMA-induced activation of the p21WAF1/CIP1 promoter was driven by the specific protein 1 (Sp1) transcription factor through Sp1-binding sites. Additionally, our study demonstrates that PMA-induces the upregulation of p21 through a protein kinase C (PKC)-mediated ROS-dependent signaling mechanism involving MAP kinase activation.
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PMID:Signal transduction of phorbol 12-myristate 13-acetate (PMA)-induced growth inhibition of human monocytic leukemia THP-1 cells is reactive oxygen dependent. 1597 37


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