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

Immune complex kinase assays in the simian virus 40 system were performed by incubation of immunoprecipitates containing tumor antigens with [gamma-32P]ATP, followed by analysis of any phosphoacceptor proteins. These assays yielded mainly the viral large T-antigen and, in particular, the associated cellular p53 as endogenous substrates. The nature of these substrates was confirmed by proteolysis techniques. Under specific conditions, casein could be used as an exogenous substrate as well. The kinase reactions showed preference for ATP and MgCl2 instead of GTP or MnCl2. Both phosphoserine and phosphothreonine, but in no case phosphotyrosine, were detected after an immune complex kinase reaction. Apparently, several in vivo phosphorylation sites were recognized in vitro in both large T-antigen and p53, but the presence of some artifactual sites could not be completely excluded. Although contaminating kinases were detectable in the immune complexes, at least the p53 molecules were phosphorylated in vitro in a more specific way. This followed from several characteristics of the immune complex kinase reactions and especially from the strong inhibition of p53 phosphorylation by two anti-large-T monoclonal antibodies. It was shown that large T-antigen showed associated kinase activity, although none of our results could unambiguously demonstrate an intrinsic kinase activity of this protein. Finally, anti-p53 monoclonal antibodies only slightly affected in vitro phosphorylation reactions, whereas a p53 molecule from a simian virus 40-free, chemically transformed human cell line was not phosphorylated in vitro under any condition tested. Thus, it is highly unlikely that the p53 molecule per se carries intrinsic or even associated kinase activities.
 ...
PMID:Protein kinase activities in immune complexes of simian virus 40 large T-antigen and transformation-associated cellular p53 protein. 632 55

A 53,000-dalton protein (p53) present in large amounts in several types of tumorigenic cells was rapidly degraded in nontumorigenic BALB/c 3T3 fibroblasts (t 1/2, approximately 0.5 h) but not in tumorigenic methylcholanthrene-induced mouse sarcoma cells (t 1/2, greater than 2 h). In 3T3 cells, dinitrophenol and 2-deoxyglucose, agents which reduce ATP production, inhibited the rapid degradation of p53 and the slower breakdown of total cell protein. After removal of these agents, the degradation of both p53 and total cell proteins resumed at their normal rates. Inhibitors of intralysosomal proteolysis (Ep475 and chloroquine) did not reduce the rate of degradation of p53. Thus, in 3T3 cells, p53 appears to be degraded by a nonlysosomal, ATP-dependent proteolytic system similar to that previously shown to degrade short- and long-lived proteins in growing fibroblasts. The immunoreactive p53 which remained in ATP-depleted cells had the same molecular weight as the p53 in the control cells. No intermediate products of p53 degradation were detected by immunoprecipitation in either ATP-depleted or control cells. Hence, ATP seems to be required for an initial step in the degradation of p53. Although the amount of labeled p53 was increased in simian virus 40-transformed and methylcholanthrene-induced mouse sarcoma cells, the amount of p53 labeled during a 3-h pulse in Moloney virus- and Rous sarcoma virus-transformed cells and untransformed 3T3 cells was similar. Thus, an increased net rate of p53 accumulation is not a common feature of transformed tumorigenic cells.
 ...
PMID:Energy requirement for degradation of tumor-associated protein p53. 632 78

A nuclear p53/55 protein kinase has been isolated from nuclear ribonucleoprotein particles from human tumor cells. The enzyme was purified approximately 2200-fold cell nuclei by sequential ribonuclease digestion of the RNP particles, DEAE cellulose and phosphocellulose chromatography. The kinase which was cAMP independent, catalyzed the phosphorylation of rabbit muscle glycogen synthase in the amino terminal domain, and conversion of the I to D form. The D synthase had a phosphorylation stoichiometry of 8 moles 32P per mole of synthase subunit with maximal specificity for ATP as phosphate donor; its Km was 30 microM. An antinucleolar antibody inhibited enzyme activity by 80%. Substrates for most other kinases were inactive. The kinase was essentially unaffected by the Walsh inhibitor, EGTA, regulatory subunits of protein kinase, calmodulin, trifluoperazine or heparin. Its activity was lost at 1 mM polyamine, but was enhanced 3-fold by MnCl2 and 4- to 9-fold by deoxymononucleotides. The nuclei of HeLa cells contained 64% of the total kinase of which 64% of the total kinase of which 11% were in nucleoli; the specific activity of the nucleolar kinase was twice that of the nuclear supernatant and four times that of the cytoplasmic kinase. These results indicate that nucleolar ribonucleoprotein particles of human tumor cells contain a cAMP-independent protein kinase which is similar to glycogen synthase kinase.
 ...
PMID:Purification of p53/55 kinase from nuclear ribonucleoproteins of Namalwa cells. 643 81

IL-7 was identified originally as a specific pre-B cell growth factor. We have investigated its signal transduction mechanism by using the human pre-B cell line Nalm-6, and have found that it stimulates tyrosine phosphorylation of various proteins: pp27, pp43, pp54, pp64, pp78, pp90, pp105, and pp120. Antiphosphotyrosine immunoprecipitates from IL-7-stimulated Nalm-6 showed two major proteins of M(r) = 60,000 and 55,000, capable of autophosphorylation. Autophosphorylation was maximal 10 min after the cells were challenged with the cytokine. Antiphosphotyrosine immunoprecipitates from IL-7-stimulated cells also increased tyrosine phosphorylation of the exogenously added substrate histone H2B. Furthermore, by using a polyclonal anti-IL-7 receptor (IL-7R) Ab in Western blotting analysis, we observed that antiphosphotyrosine immunoprecipitates were associated with the IL-7R in a transient manner. These data indicate that the IL-7R associates with tyrosine-phosphorylated proteins as its amino acid sequence is devoid of a putative site of tyrosine phosphorylation. These results were confirmed as several 32P-labeled proteins were visualized after immunoprecipitation by using anti-IL-7R Ab. Anti-IL-7R immunoprecipitates from IL-7-stimulated cells revealed a unique band of M(r) = 60,000 associated with the receptor able to autophosphorylate in the presence of ATP and Mn2+. Hence, we identified p59fyn and p53/56lyn to be stimulated by IL-7. In contrast to p53/56lyn, p59fyn was found to be associated constitutively with the cloned IL-7R. These data emphasize the role of the src family in hematopoiesis.
 ...
PMID:Activation of src family kinases in human pre-B cells by IL-7. 751 33

Aggregation of the high-affinity receptors for IgE (Fc epsilon RI) on mast cells activates nonreceptor kinases and other enzymes, thereby initiating a complex biochemical cascade. We have employed a chemical cross-linker in order to stabilize the association of Fc epsilon RI with other cellular proteins that are involved in the early events. We reacted the water-soluble, membrane-impermeant chemical cross-linker 3,3'-dithiobis(sulfosuccinimidyl propionate) (DTSSP) with permeabilized rat mucosal mast cells of the RBL line and analyzed immunoprecipitates of the receptor in detergent lysates of cells that had biosynthetically incorporated [35S]cysteine. Gel electrophoresis revealed substantial amounts of nonreceptor components only when the cells had been reacted with DTSSP. Receptors isolated from cells whose receptor-bound IgE had been aggregated with antigen prior to cross-linking yielded a similar pattern of 35S-labeled proteins. However, when the cells had also been exposed to [gamma-32P]ATP, the proteins associated with the cross-linked, aggregated receptors revealed enhanced incorporation of 32P compared to those associated with cross-linked, unaggregated receptors. A variety of antibodies were used to try to identify the associated proteins. Of those tested for, two, the src-like kinase p53/56lyn and the delta isoform of protein kinase C, were associated with the cross-linked Fc epsilon RI in amounts much greater than could be accounted for by nonspecific cross-linking.
 ...
PMID:Chemical cross-linking of IgE-receptor complexes in RBL-2H3 cells. 753 96

Gene therapy clinical trials targeting p53 and other genes are underway in nongynecologic cancer systems. To explore the potential for antigene therapy in gynecologic oncology, we examined the in vitro effects of oligonucleotides targeting c-myc and p53 in the ovarian cancer cell lines CAOV-3, SKOV-3, and BG-1. The ATP cell viability assay was used to measure growth effects after 6-day treatments with 27-mer antisense phosphorothioate oligodeoxyribonucleotides (oligos) targeting the Puf/nm23 binding region of c-myc and promoter/ATG region of p53. A random sequence of the p53 27-mer was used as a control, and an untransformed fibroblast cell line was used for comparison. IC50 was defined as the oligo concentration required for 50% growth reduction compared to untreated controls. Synergistic vs antagonistic effects of oligo combinations were quantitated by combination indexes (CI) as calculated from median effect parameters by the methods of Chou and Talalay. Mean +/- SE IC50's of c-myc and p53 antisense oligos in CAOV-3 and SKOV-3 ranged from 1.0 +/- 0.2 to 9.7 +/- 1.3 microM. The IC50's of c-myc oligos were consistently lower than corresponding p53 oligos in all cell lines (P < 0.034, t test). The fibroblast cell line was sensitive to anti-c-myc and combination anti-c-myc/p53 oligos (IC50 = 1.5 +/- 0.6 and 1.4 +/- 0.2 microM, respectively), but not to anti-p53 oligos alone (IC50 > 16 microM). Nonspecific toxicity was observed at concentrations of 16 microM for all cell lines except in BG-1, where maximal growth stimulation occurred at this concentration with anti-p53 oligos. Growth stimulation was also observed in BG-1 with anti-c-myc and anti-c-myc/p53 combinations at intermediate doses, with inhibition at higher doses. While c-myc/p53 combinations in CAOV-3 were synergistic (CI < 0.8), they were antagonistic in SKOV-3 (CI > 3.2). Phosphorothioate oligos directed against c-myc and p53 in different cell lines were shown to have both antiproliferative and stimulatory activity, as single agents and in combination, at concentrations that are achievable in vivo. Because of the complex patterns of effects, further in vitro studies are warranted before considering clinical trials with these agents in gynecologic cancers.
 ...
PMID:Combination anti-gene therapy targeting c-myc and p53 in ovarian cancer cell lines. 755 22

Screening for inhibitors of DNA-dependent protein kinase (DNA-PK) revealed 3-cyano-5-(4-pyridyl)-6-hydrazonomethyl-2-pyridone, designated OK-1035, to be a potent and selective inhibitor. When a synthetic peptide was used as a substrate, OK-1035 caused 50% inhibition of DNA-PK activity at 8 microM, a concentration more than 50 times lower than those required against seven other protein kinases tested. OK-1035 inhibited the phosphorylation by DNA-PK of consensus peptide as well as that of recombinant human wild type-p53. Kinetic studies indicated that OK-1035 inhibited DNA-PK activity in an ATP-competitive manner.
 ...
PMID:OK-1035, a selective inhibitor of DNA-dependent protein kinase. 757 20

The mechanisms underlying cell death are reviewed in order to propose new targets for the therapy of gastrointestinal disease. Necrosis is a set of precise biochemical and cellular lesions which culminate in cell destruction. A number of potential targets for drug therapy are discussed which will inhibit necrosis, including preservation of cellular ATP by inhibition of poly(ADP-ribose) polymerase. Such therapies may be useful either as adjuncts to other therapeutic modalities such as immunosuppressive agents for the treatment of inflammatory conditions or on their own for organ preservation prior to organ transplantation. Either excessive apoptosis or failure of apoptosis plays an important role in a variety of gastrointestinal diseases. Failure of apoptosis is of particular importance in the development of colorectal cancer. Mutations or deletions of p53, bcl-2 and myc prevents the appropriate deletion of malignant cells and causes resistance to anti-cancer drugs which act by the induction of apoptosis. Correction of these genetic defects or replacement of their function is a major strategy in cancer prevention and therapy. It is concluded that manipulation of cell death processes is an important new area for gastrointestinal research.
 ...
PMID:Review article: manipulation of cell death--the development of novel strategies for the treatment of gastrointestinal disease. 765 84

Cells and tissues have developed a variety of ways of responding to a hostile environment, be it from drugs (toxins) or radiation (summarized in Fig. 1). Three categories of radiation damage limitation are: (i) DNA repair (ii) changes in cellular metabolism (iii) changes in cell interaction (cell contact or tissue-based resistance; whole organism based resistance). DNA repair has been evaluated predominantly by the study of repair-deficient mutants. The function of the repair genes they lack is not fully understood, but some of their important interactions are now characterized. For example, the interaction of transcription factors with nucleotide excision repair is made clear by the genetic syndromes of xeroderma-pigmentosum groups B, D and G. These diseases demonstrate ultraviolet light sensitivity and general impairment of transcription: they are linked by impaired unwinding of the DNA required for both transcription and repair. The transfer of DNA into cells is sometimes accompanied by a change in sensitivity to radiation, and this is of special interest when this is the same genetic change seen in tumors. DNA repair has a close relationship with the cell cycle and cell cycle arrest in response to damage may determine sensitivity to that damage. DNA repair mechanisms in response to a variety of drugs and types of radiation can be difficult to study because of the inability to target the damage to defined sequences in vivo and the lack of a satisfactory substrate for in vitro studies. Changes in cellular metabolism as a result of ionizing radiation can impart radiation resistance, which is usually transient in vitro, but may be more significant in vivo for tissues or tumors. The mechanisms by which damage is sensed by cells is unknown. The detection of free radicals is thought likely, but distortion to DNA structure or strand breakage and a direct effect on membranes are other possibilities for which there is evidence. Changes in extracellular ATP occur in response to damage, and this could be a direct membrane effect. External purinergic receptors can then be involved in signal transduction pathways resulting in altered levels of thiol protection or triggering apoptosis. Changes in the functional level of proteins as a consequence of ionizing radiation include transcription factors, for example c-jun and c-fos; cell cycle arrest proteins such as GADD (growth arrest and DNA damage inducible proteins) and p53; growth factors such as FGF, PDGF; and other proteins leading to radioresistance.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:The biology of radioresistance: similarities, differences and interactions with drug resistance. 776 55

An oncogene product, p53, interacts with a simian virus 40-encoded T-antigen, which is an initiation protein for the viral DNA replication and also works as DNA helicase during elongation. Here we examine the interaction of p53 with cellular DNA helicase. A recombinant human wild type p53 fused with glutathione S-transferase was immobilized on glutathione-agarose as a ligand for affinity column. Hela cell extract was applied to the p53 column and the adsorbed proteins were eluted with buffers containing salt, 50% ethylene glycol, and glutathione. The ethylene glycol fraction contained a number of p53 binding proteins, and this fraction showed a DNA helicase activity measured by the displacement of DNA fragment from partially duplexed M13 DNA. The DNA helicase translocated in a 5'-to-3' direction on the single-stranded DNA using ATP as an energy source. The glutathione fraction that contained the p53 glutathione S-transferase fused protein also showed the same activity. The corresponding fractions from a control column carrying glutathione S-transferase showed only a trace amount of activity of DNA helicase. Therefore, the binding may be specific. Furthermore, an anti-p53 antibody column retained a p53-DNA helicase complex when the crude extracts of human placenta and of osteosarcoma cells were applied. These results indicate that p53 physically interacts with DNA helicase in vitro as well as in vivo.
 ...
PMID:Anti-oncogene product p53 binds DNA helicase. 795 81


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>