Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infection of HeLa cells with poliovirus leads to rapid shut-off of host cell transcription by RNA polymerase II. Previous results have suggested that both the basal transcription factor TBP (TATA-binding protein) and transcription activator proteins such as CREB (cyclic AMP-responsive element-binding protein) and Oct-1 (the octamer-binding factor) are cleaved by the viral-encoded protease, 3C(Pro). Here we demonstrate that the transcriptional activator (and tumor suppressor) p53 is degraded by the viral protease 3C both in vivo and in vitro. Unlike other transcription factors that are directly cleaved by 3C(pro), degradation of p53 requires a HeLa cell activity in addition to 3C(Pro). The degradation of p53 by 3C(Pro) does not appear to involve the ubiquitin pathway of protein degradation. Vaccinia virus infection of HeLa cells leads to inactivation of the cellular activity required for 3C(Pro)-mediated degradation of p53. The vaccinia-encoded protein (CrmA) is known to inhibit caspase I (ICE protease) that converts inactive IL-1beta to an active secreted form. Incubation of HeLa cells with caspase I inhibitor Z-VAD-fmk does not interfere with 3C(Pro)-mediated degradation of p53. The cellular activity present in extracts of HeLa cells can be fractionated through phosphocellulose. A partially purified fraction that elutes at 0.6 M KCl from phosphocellulose contains the activity that degrades p53 in a 3C(Pro)-dependent manner. These results suggest that both poliovirus-encoded protease 3C(Pro) and a cellular activity are required for the degradation of p53 observed in cells infected with poliovirus.
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PMID:Poliovirus 3C protease-mediated degradation of transcriptional activator p53 requires a cellular activity. 1187 95

The vaccinia-related kinase 1 (VRK1) protein is a nuclear Ser-Thr kinase that phosphorylates p53 in Thr18. We have determined the enzyme properties regarding its different substrates. VRK1 has a high affinity for ATP (K(m) 50 microM) and is thus saturated by the intracellular concentration of ATP in vivo. VRK1 uses preferentially magnesium, but is also functional with manganese and zinc. The VRK1 protein is autophosphorylated in multiple residues without effect on its activity. One autophosphorylated residue, T355, is within the VRK1 regulatory carboxy terminus. The kinase phosphorylates p53 with a K(m) of 1 microM and is well suited to respond to the variations of intracellular p53 concentration, which fluctuates as a response to different types of cellular stress.
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PMID:Kinetic properties of p53 phosphorylation by the human vaccinia-related kinase 1. 1188 97

Potent and safe vaccinia virus vectors inducing cell-mediated immunity are needed for clinical use. Replicating vaccinia viruses generally induce strong cell-mediated immunity; however, they may have severe adverse effects. As a vector for clinical use, we assessed the defective vaccinia virus system, in which deletion of an essential gene blocks viral replication, resulting in an infectious virus that does not multiply in the host. The vaccinia virus Lister/Elstree strain, used during worldwide smallpox eradication, was chosen as the parental virus. The immunogenicity and safety of the defective vaccinia virus Lister were evaluated without and with the inserted human p53 gene as a model and compared to parallel constructs based on modified vaccinia virus Ankara (MVA), the present "gold standard" of recombinant vaccinia viruses in clinical development. The defective viruses induced an efficient Th1-type immune response. Antibody and cytotoxic-T-cell responses were comparable to those induced by MVA. Safety of the defective Lister constructs could be demonstrated in vitro in cell culture as well as in vivo in immunodeficient SCID mice. Similar to MVA, the defective viruses were tolerated at doses four orders of magnitude higher than those of the wild-type Lister strain. While current nonreplicating vectors are produced mainly in primary chicken cells, defective vaccinia virus is produced in a permanent safety-tested cell line. Vaccines based on this system have the additional advantage of enhanced product safety. Therefore, a vector system was made which promises to be a valuable tool not only for immunotherapy for diseases such as cancer, human immunodeficiency virus infection, or malaria but also as a basis for a safer smallpox vaccine.
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PMID:Immunogenicity and safety of defective vaccinia virus lister: comparison with modified vaccinia virus Ankara. 1209 85

Different vaccine constructs based on DNA vaccines and viral recombinant vaccines expressing mouse p53 were compared for induction of protective immune responses to challenge with a sarcoma cell line that expresses high levels of mutated p53 protein. Viral recombinant vaccines based on E1-deleted adenovirus or vaccinia virus recombinants expressing p53 with wild-type sequences in the mutational hotspot domain and a single mutation in the tetramerization domain (p53(mu338)) failed to induce protection against progression of this tumor cell line. A DNA vaccine expressing a form of p53 carrying the same point mutations as the tumor cell line showed low efficacy that was comparable to that of a DNA vaccine expressing p53(mu338). Efficacy of the DNA vaccine was augmented upon expressing p53(mu338) as a fusion protein linked to a viral leader sequence. Other modifications such as fusion to the signal sequence of the lysosome-associated membrane protein (LAMP) or ubiquitin failed to improve the efficacy of the vaccine to p53. Protection mediated by CD4(+) and CD8(+) T cells was specific for p53.
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PMID:A modified DNA vaccine to p53 induces protective immunity to challenge with a chemically induced sarcoma cell line. 1214 33

Inoculation of mice with a recombinant vaccinia virus expressing the full-length mouse wild-type p53 protein (Vp53-wt) was shown to induce partial protection against peripheral challenge with a mouse glioblastoma cell line, termed GL261, expressing high levels of nuclear, endogenous wild-type p53. In vivo experiments with knockout (KO) mice and mice treated with depleting doses of antibodies specific to lymphocyte subsets revealed that vaccine efficacy depended on CD4+ and CD8+ T cells as well as on natural killer (NK) cells. Vp53-wt virus-vaccinated mice that failed to develop tumours upon challenge with a minimal tumourigenic dose of GL261 cells remained completely resistant to further challenge with increased doses of GL261 cells. The efficacy of the Vp53-wt vaccine was improved by adding recombinant mouse interleukin-12 (rIL-12) as an adjuvant at the time of tumour challenge. The induction of T cells to p53 in Vp53-wt virus-immune mice was also demonstrated at the tumour site by immunochemistry and was further confirmed by a delayed-type hypersensitivity response to the p53 protein, although in vitro experiments using splenocytes from vaccinated mice failed to demonstrate CD4+ or CD8+ T-cell activity to p53.
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PMID:An experimental vaccine expressing wild-type p53 induces protective immunity against glioblastoma cells with high levels of endogenous p53. 1223 57

p53 is overexpressed by half of all cancers, and is an attractive target for a vaccine approach to immunotherapy. p53 overexpression is frequently the result of point mutations, which leaves the majority of the protein in its wild-type form. Therefore, the majority of p53 sequence is wild type, making it a self-protein for which tolerance plays a role in limiting immune responses. To overcome tolerance to p53, we have expressed wild-type murine p53 in the nonpathogenic attenuated poxvirus, modified vaccinia virus Ankara (recombinant modified vaccinia virus Ankara expressing wild-type murine p53 (rMVAp53)). Mice immunized with rMVAp53 vaccine developed vigorous p53-specific CTL responses. rMVAp53 vaccine was evaluated for its ability to inhibit the outgrowth of the syngeneic murine sarcoma Meth A, which overexpresses mutant p53. Mice were inoculated with a lethal dose (5 x 10(5) cells injected s.c.) of Meth A tumor cells and vaccinated by i.p. injection 3 days later with 5 x 10(7) PFU of rMVAp53. The majority of mice remained tumor free and resistant to rechallenge with Meth A tumor cells. We wished to determine whether rMVAp53 immunization could effect the rejection of an established, palpable Meth A tumor. In subsequent experiments, mice were injected with 10(6) Meth A tumor cells, and treated 6 days later with anti-CTLA-4 Ab (9H10) and rMVAp53. The majority of treated mice had complete tumor regression along with lasting tumor immunity. In vivo Ab depletion confirmed that the antitumor effect was primarily CD8 and to a lesser extent CD4 dependent. These experiments demonstrate the potential of a novel cell-free vaccine targeting p53 in malignancy.
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PMID:CTLA-4 blockade enhances the therapeutic effect of an attenuated poxvirus vaccine targeting p53 in an established murine tumor model. 1262 1

The overall goal of this study was to analyze the effect and mechanism of radiation in combination with vaccinia viruses (VV) carrying the p53 gene against glioma. Comparison of two alternative treatments of cultured C6 (p53(+)) and 9L (p53(-)) rat glioma cells showed significantly reduced survival for both cell lines, especially 9L, when radiation was applied prior to virus versus radiation alone. High p53 protein expression mediated by VV-TK-p53 was measured in infected cells. Single modality treatment of C6 cells with psoralen and UV (PUV)-inactivated VV-TK-p53 (PUV-VV-TK-53) or radiation significantly decreased survival compared with PUV-inactivated L-15 (PUV-L-15) control virus. However, no difference was observed between radiation and combination treatments of C6 cells. In contrast, radiation followed by PUV-VV-TK-53 resulted in dramatic reduction of 9L cell viability, compared to single modality treatment. Flow cytometry analysis of Annexin-V-stained 9L cells showed that radiation and PUV-VV-TK-53 caused a significant decrease in live cells (17.2%) as compared to other treatments and control (61.6-98.3%). Apoptosis was observed in 37.2% of cells, while the range was 0.7-7.8% in other treatment groups; maximal p53 level was measured on day 7 post-infection. In athymic mice bearing C6 tumors, VV-TK-53 plus radiation in both single and multiple therapies resulted in significantly smaller tumors by day 30 compared to the agents given only once. Immunohistochemical analysis of tumor sections demonstrated p53 protein expression over 20 days after VV-TK-53 treatment. Analysis of blood and spleen cells of mice given multiple combination treatments showed significant splenomegaly, leukocytosis, and increased DNA synthesis and response to mitogen. Multiple combination treatments were also associated with significantly elevated natural killer and B cells in the spleen. There were no overt toxicities, although depression in red blood cell and thrombocyte parameters was noted. Collectively, the data demonstrate that radiation significantly improves the efficacy of VV-mediated tumor suppressor p53 therapy and may be a promising strategy for glioma treatment. Furthermore, the results support the conclusion that the mechanisms underlying the enhanced anti-tumor effect of combination treatment include apoptosis/necrosis and upregulation of innate immune defenses.
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PMID:Radiation enhances the anti-tumor effects of vaccinia-p53 gene therapy in glioma. 1277 53

The vaccinia-related kinase (VRK) proteins are a new group of three Ser-Thr kinases in the human kinome. VRK proteins are upstream regulators of several transcription factors. VRK1 phosphorylates p53 in Thr-18 within the region of binding to mdm2 preventing their interaction. The tissue distribution of three genes is still largely unknown. In the present report the expression of these genes was analyzed during murine hematopoietic development. The three genes are expressed in fetal liver and peripheral blood, with higher levels between days 11.5 and 13.5, a time when there is a massive expansion of liver cells, and thereafter their expression falls significantly. VRK genes are expressed, particularly at mid-gestation, in embryo thymus and spleen, but in adult thymus and spleen their levels are very low. VRK2 is expressed at lower levels than VRK1 and VRK3 in the mouse embryo. VRK genes play a role during embryonic development of hematopoiesis.
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PMID:Expression of the VRK (vaccinia-related kinase) gene family of p53 regulators in murine hematopoietic development. 1278 11

By using a vaccinia virus-T7 expression system, possible effects of hepatitis C virus (HCV) core protein on synthesis and accumulation of host cellular proteins transiently expressed in cultured cells were analyzed. Immunoblot and immunofluorescence analyses revealed that synthesis and accumulation of certain nuclear proteins, such as p21/Waf1, p53, proliferating cell nuclear antigen and c-Fos, were strongly inhibited by HCV core protein. On the other hand, synthesis and accumulation of cytoplasmic proteins, such as 2'-5'-oligoadenylate synthetase (2'-5'-OAS), RNase L and MEK1, were barely affected by HCV core protein. Northern blot analysis showed that the degrees of mRNA expression for those proteins did not differ between HCV core protein-expressing cells and the control, suggesting that the inhibition occurred at the post-transcription level. Pulse-labeling analysis suggested that HCV core protein strongly inhibited synthesis of p21/Waf1 at the translation level. Once being accumulated in the nucleus, p21/Waf1 stability was not significantly affected by HCV core protein. Mutants of HCV core protein C-terminally deleted by 18 or 41 amino acids (aa), which were localized almost exclusively in the nucleus, lost their ability to inhibit synthesis/accumulation of p21/Waf1 whereas another mutant C-terminally deleted by 8 aa still maintained the same properties (subcellular localization and the inhibitory effect) as the full-length HCV core protein of 191 aa. Taken together, our present results suggest that expression of HCV core protein in the cytoplasm selectively inhibits synthesis of p21/Waf1 and some other nuclear proteins at the translation level.
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PMID:Hepatitis C virus core protein selectively inhibits synthesis and accumulation of p21/Waf1 and certain nuclear proteins. 1290 3

Local radiation is an established therapy for human tumors. Radiation also has been shown to alter the phenotype of target tissue, including gene products that may make tumor cells more susceptible to T-cell-mediated immune attack. We demonstrate a biological synergy between local radiation of tumor and active vaccine therapy. The model used consisted of mice transgenic for human carcinoembryonic antigen (CEA) and a murine carcinoma cell line transfected with CEA. The vaccine regimen consisted of a prime and boost strategy using vaccinia and avipox recombinants expressing CEA and three T-cell costimulatory molecules. One dose of 8-Gy radiation to tumor induced up-regulation of the death receptor Fas in situ for up to 11 days. However, neither radiation at this dose nor vaccine therapy was capable of inhibiting growth of 8-day established tumor. When vaccine therapy and local radiation of tumor were used in combination, dramatic and significant cures were achieved. This was mediated by the engagement of the Fas/Fas ligand pathway because Ag-bearing tumor cells expressing dominant-negative Fas were not susceptible to this combination therapy. Following the combination of vaccine and local radiation, tumors demonstrated a massive infiltration of T cells not seen with either modality alone. Mice cured of tumors demonstrated CD4(+) and CD8(+) T-cell responses specific for CEA but also revealed the induction of high levels of T-cell responses to two other antigens (gp70 and p53) overexpressed in tumor, indicating the presence of a consequential antigen cascade. Thus, these studies demonstrate a new paradigm for the use of local tumor irradiation in combination with active specific vaccine therapy to elicit durable antitumor responses of established tumors.
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PMID:External beam radiation of tumors alters phenotype of tumor cells to render them susceptible to vaccine-mediated T-cell killing. 1520 48


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