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)

Aggregation of the high affinity IgE receptors (Fc epsilon RI) on rat basophilic leukemia RBL-2H3 cells results in protein tyrosine phosphorylations. Previously we reported that there is prominent tyrosine phosphorylation of approximately 72-kDa proteins (pp72) and that the tyrosine kinase p72syk is one component of pp72. Here we studied further the relationship of p72syk to pp72. The aggregation of Fc epsilon RI induced the activation of p72syk which was parallel to its tyrosine phosphorylation. By in vitro kinase assay of immune complexes purified with anti-phosphotyrosine antibodies, p72syk was the major pp72 tyrosine kinase. However, by immunoblotting with anti-phosphotyrosine antibodies, p72syk was a minor component of pp72. The heterogeneous nature of pp72 was indicated by different studies. Under optimum conditions of one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, pp72 consisted of a heterogeneous group of 69-, 71-, and 72-kDa tyrosine-phosphorylated proteins. There were differences in the tyrosine phosphorylation of these proteins in cells activated in the absence of extracellular calcium or when stimulation was with the calcium ionophore A23187 or with phorbol myristate acetate. One of the proteins migrating at 69 kDa was p72syk. By two-dimensional gel electrophoresis pp72 was found to consist of multiple tyrosine-phosphorylated protens including 71-80-kDa proteins that associate with p53/56lyn. A 75-kDa tyrosine-phosphorylated protein, different from pp72, was identified as p75HS1 (SPY75). These results demonstrate the heterogeneous nature of the pp72 and that p72syk is activated after Fc epsilon RI aggregation.
 ...
PMID:Activation of protein tyrosine kinase p72syk by Fc epsilon RI aggregation in rat basophilic leukemia cells. p72syk is a minor component but the major protein tyrosine kinase of pp72. 751 87

The tumor suppressor protein p53 is a metal-binding transcription factor whose conformation and function are altered by mutation in cancers. Using murine p53 translated in vitro, we report here that concentrations of copper within the physiological range (< 30 microM) alter the conformation of wild-type p53 and inhibit sequence-specific DNA-binding. Direct binding of copper to p53 in the form of Cu(I) was demonstrated by Electron Spin Resonance using a purified recombinant protein containing residues 1-343 of murine wild-type p53 fused to E. coli maltose binding protein. Moreover, protection against the effect of Cu(II) sulfate was achieved by the Cu(I)-specific chelator bathocuproinedisulfonic acid but not by scavengers of reactive oxygen species, suggesting that alteration of p53 by copper depends upon a Cu(II)/Cu(I) redox mechanism, but does not require the production of reactive oxygen species. Thus copper at physiological concentrations can interact with wild-type p53 and affect its DNA-binding capacity.
 ...
PMID:Modulation by copper of p53 conformation and sequence-specific DNA binding: role for Cu(II)/Cu(I) redox mechanism. 782 76

Inhibin-alpha-deficient mutant mice have been generated by a targeted deletion of the inhibin-alpha gene through homologous recombination in murine embryonic stem cells. Essentially all of the homozygous mutants develop gonadal sex cord-stromal tumors. To investigate their endocrine and proliferative characteristics, gonadal tumor cells were maintained in vitro. Cells from inhibin-alpha-deficient mice multiplied poorly; however, cells from mice deficient in both inhibin-alpha and p53 proliferated rapidly and showed higher saturation density and plating efficiency, thus allowing the establishment of clonal tumor cell lines. Although negligible estrogen and testosterone was produced by the clonal cells, high levels of progesterone were secreted. A clonal testis tumor cell line (inhibin-alpha/p53 deficient) showed no response to exogenous FSH, human CG (hCG), or inhibin A but exhibited a 6- to 8-fold increase in progesterone production in response to forskolin treatment. The stimulatory effect of forskolin was, however, partially blocked by activin treatment. Northern blot analysis revealed inhibin beta A and beta B mRNA expression in these cells. Furthermore, Western blot analyses indicated the secretion of the beta A-subunit protein. We further tested the role of activin on tumor cell growth. Treatment with follistatin, an activin-binding protein, inhibited tumor cell replication in a dose-dependent manner. In contrast, treatment with activin A stimulated tumor cell growth by itself and partially blocked follistatin action. Incorporation of thymidine into DNA of these cells was also stimulated by activin. In addition, treatment with antiactivin A serum inhibited tumor cell replication and blocked the stimulatory action of activin on cell growth. The activin action is likely mediated by specific receptors because cross-linking of [125]activin to the 50-55 kilodalton type I and 75-80 kilodalton type II receptors was found using sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Northern blot analysis also revealed follistatin mRNA expression in the tumor cells, suggesting these cells are related to granulosa cells. Our findings indicate that activin can act as an autocrine growth factor in stimulating the proliferation of gonadal tumor cell lines derived from inhibin-alpha and p53-deficient mice and inhibits progesterone production. These tumor cell lines are useful for studies on the regulation of gonadal cell proliferation and steroidogenesis as well as the signaling pathway mediating activin action.
 ...
PMID:Characterization of gonadal sex cord-stromal tumor cell lines from inhibin-alpha and p53-deficient mice: the role of activin as an autocrine growth factor. 799 39

Expression of simian virus 40 (SV40) large T antigen efficiently immortalizes and transforms primary cells. We previously reported that a hybrid polyomavirus-SV40 large T antigen, PyT1-521-SVT336-708, binds to both p53 and pRb but does not transform an established rat cell line (J. J. Manfredi and C. Prives, J. Virol. 64:5250-5259, 1990). Here we show that this hybrid large T antigen is capable of immortalizing primary rat cells. Plasmids that express resistance to G418 sulfate and either SV40 large T antigen or PyT1-521-SVT336-708 were transfected into primary rat embryo fibroblasts, and cell lines were established. The cell lines that expressed PyT1-521-SVT336-708 were not fully transformed but did exhibit altered growth properties. Although these PyT1-521-SVT336-708-expressing lines did not form foci, they did grow in low serum and grew to a high saturation density; these cell lines also formed colonies in soft agar, but their colonies were much smaller than those seen with an SV40 large-T-antigen-expressing line. PyT1-521-SVT336-708 also demonstrated the ability to cooperate with activated Ha-ras to form foci on primary rat embryo fibroblasts. Surprisingly, two types of morphologies in such lines were observed: refractile and spindle shaped. Although there was no correlation between T-antigen level and morphology, all lines that displayed refractile morphology expressed high levels of p21ras. Since the p53 binding activity of PyT1-521-SVT336-708 appears to be intact, these results suggest that there are functions residing in the amino end of SV40 large T antigen which are necessary for full transformation that are missing from the amino end of polyomavirus large T antigen. Conversely, conferring the ability to bind to p53 on an amino-terminal fragment of polyomavirus large T antigen, although not enough to allow full transformation function, does increase its oncogenic activity in saturation density and soft agar growth assays.
 ...
PMID:Primary rat cells expressing a hybrid polyomavirus-simian virus 40 large T antigen have altered growth properties. 839 12

The p53 protein was identified in primary breast carcinomas by specific binding of PAb1801 and PAb240 antibodies. Using sodium dodecyl sulfate electrophoresis followed by immunoblotting on nitrocellulose membrane, the p53 protein was identified in 36 nuclear fractions obtained from 60 primary breast cancers; semiquantitation of p53 was performed by densitometric scanning. The total cathepsin D content, the estrogen and progesterone receptor concentration values and the axillary lymph node involvement were also assessed. Tumors expressing p53 had significantly higher levels of cathepsin D than those in which p53 was undetectable. p53 expression was strongly associated with low or negative estrogen receptor values; progesterone receptor concentrations were also significantly higher in p53-negative tumors than in those tumors with detectable p53 levels. Finally, a significant relationship between p53 expression and lymph node metastasis was observed. It was concluded that a positive association between p53 and cathepsin D values exists which is of prognostic interest in that both cathepsin D and p53 are associated with a high tumor grade and metastatic activity.
 ...
PMID:p53 associated with cathepsin D in primary breast cancer. 851 12

Hydrazine sulfate is a genotoxic hepatocarcinogen for the hamster. A study was conducted to follow changes in DNA maintenance methylation in selected genes in liver DNA during the 21-month induction of liver adenomas and hepatocellular carcinomas by demonstrating changes in restriction fragment length polymorphism. Male Syrian golden hamsters were exposed to hydrazine sulfate in the drinking water at three concentrations (170, 340 and 510 mg/l) shown previously to result in a dose-dependent induction of liver tumors. Liver DNA from animals exposed to the high concentration for 6, 12, 16, 20 and 21 months and animals exposed to the low or mid concentration for 21 months was digested with EcoRI, MspI, HindIII or BamHI, or a combination of one of these endonucleases and a methyl-sensitive restriction enzyme, HpaII or HhaI. The DNA digests were subjected to Southern analysis using a c-DNA probe for one of the following genes: DNA methyltransferase (DMT), c-Ha-ras, c-jun, c-fos, and c-myc proto-oncogenes, p53 tumor suppressor gene or gamma-glutamyltranspeptidase. Alteration in DNA restriction by methyl-sensitive endonucleases was detected in four (DMT, c-Ha-ras, p53 and c-jun) of the seven genes examined and as early as 6 months in animals exposed to the highest concentration of hydrazine sulfate; alteration of recognition sites in c-Ha-ras was also detected in DNA from animals exposed for 21 months to the intermediate concentration of hydrazine sulfate. Early changes in recognition sites, presumed to indicate altered methylation status of DNA cytosine and/or guanine mutations, were seen using c-DNA probes for DMT, c-Ha-ras and c-jun; in the p53 tumor suppressor gene alteration of such sites was a late event relevant to appearance of liver adenomas and hepatocellular carcinomas. Evidence for hypomethylation in the p53 and c-jun genes and hypermethylation of the c-Ha-ras and DMT genes is provided. This study supports the induction of site-specific hypomethylation and hypermethylation during the course of hydrazine carcinogenesis.
 ...
PMID:Changes in methyl-sensitive restriction sites of liver DNA from hamsters chronically exposed to hydrazine sulfate. 900 10

Our previous finding that the tumor suppressor p53 is covalently linked to 5.8S rRNA suggested functional association of p53 polypeptide with ribosomes. p53 polypeptide is expressed at low basal levels in the cytoplasm of normal growing cells in the G1 phase of the cell cycle. We report here that cytoplasmic wild-type p53 polypeptide from both rat embryo fibroblasts and MCF7 cells and the A135V transforming mutant p53 polypeptide were found associated with ribosomes to various extents. Treatment of cytoplasmic extracts with RNase or puromycin in the presence of high salt, both of which are known to disrupt ribosomal function, dissociated p53 polypeptide from the ribosomes. In immunoprecipitates of p53 polypeptide-associated ribosomes, 5.8S rRNA was detectable only after proteinase K treatment, indicating all of the 5.8S rRNA in p53-associated ribosomes is covalently linked to protein. While 5.8S rRNA linked to protein was found in the immunoprecipitates of either wild-type or A135V mutant p53 polypeptide associated with ribosomes, little 5.8S rRNA was found in the immunoprecipitates of the slowly sedimenting p53 polypeptide, which was not associated with ribosomes. In contrast, 5.8S rRNA was liberated from bulk ribosomes by 1% sodium dodecyl sulfate, without digestion with proteinase K, indicating that these ribosomes contain 5.8S rRNA, which is not linked to protein. Immunoprecipitation of p53 polypeptide coprecipitated a small fraction of ribosomes. p53 mRNA immunoprecipitated with cytoplasmic p53 polypeptide, while GAPDH mRNA did not. These results show that cytoplasmic p53 polypeptide is associated with a subset of ribosomes, having covalently modified 5.8S rRNA.
 ...
PMID:Cytoplasmic p53 polypeptide is associated with ribosomes. 915 13

Protein kinase Cmu is a novel member of the protein kinase C (PKC) family that differs from the other isoenzymes in structural and enzymatic properties. No substrate proteins of PKCmu have been identified as yet. Moreover, the regulation of PKCmu activity remains obscure, since a structural region corresponding to the pseudosubstrate domains of other PKC isoenzymes has not been found for PKCmu. Here we show that aldolase is phosphorylated by PKCmu in vitro. Phosphorylation of aldolase and of two substrate peptides by PKCmu is inhibited by various proteins and peptides, including typical PKC substrates such as histone H1, myelin basic protein, and p53. This inhibitory activity seems to depend on clusters of basic amino acids in the protein/peptide structures. Moreover, in contrast to other PKC isoenzymes PKCmu is activated by heparin and dextran sulfate. Maximal activation by heparin is about twice and that by dextran sulfate four times as effective as maximal activation by phosphatidylserine plus 12-O-tetradecanoylphorbol-13-acetate, the conventional activators of c- and nPKC isoforms. We postulate that PKCmu contains an acidic domain, which is involved in the formation and stabilization of an active state and which, in the inactive enzyme, is blocked by an intramolecular interaction with a basic domain. This intramolecular block is thought to be released by heparin and possibly also by 12-O-tetradecanoylphorbol-13-acetate/phosphatidylserine, whereas basic peptides and proteins inhibit PKCmu activity by binding to the acidic domain of the active enzyme.
 ...
PMID:Regulation of protein kinase Cmu by basic peptides and heparin. Putative role of an acidic domain in the activation of the kinase. 925 96

We describe and discuss a method of protein extraction for Western blot analysis from formalin-fixed, paraffin-embedded tissue sections. From 5-mm2 50-micron-thick tissue sections, an abundance of proteins could be extracted by incubating the sections in lysis buffer containing 2% sodium dodecyl sulfate (SDS) at 100C for 20 min followed by incubation at 60C for 2 hr. Extracts yielded discernible protein bands ranging from 10 kD to 120 kD as identified by SDS-polyacrylamide gel electrophoresis (PAGE). Western blot analysis successfully detected membrane-bound protein such as E-cadherin, cytosolic protein such as beta-catenin, and nuclear proteins including proliferating cell nuclear antigen (PCNA), mutant-type p53, cyclin D1, cyclin E, and cyclin-dependent kinases (CDKs). With this technique, we could examine cyclin D1 and CDK2 expression in small adenomas compared with cancer tissues and normal mucosa. The simple method of protein extraction described here should make it possible to use large-scale archives of formalin-fixed, paraffin-embedded samples for Western blot analysis, and its application could lead to detailed analysis of protein expression. This new technique should yield valuable information for molecular biology.
 ...
PMID:Extraction and analysis of diagnostically useful proteins from formalin-fixed, paraffin-embedded tissue sections. 948 22

Three sources of fetal bovine serum (FBS) were fractionated by ammonium sulfate precipitation and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), transferred to Immobilon-P membranes, immunoblotted with a panel of transcription factor antibodies, and detected by enhanced chemiluminescence. Nine transcription factors were detected--ATF-2, SRE-ZBP, GATA-2, TFIID, Ets-1/Ets-2, E2F-1, Oct-2, p53, and AP-2; four transcription factors were not detected--Myo D, CREB, Sp2, and Wilms' tumor. The results indicated the presence of varying amounts of several transcription factors in three commercial sources and may represent heretofore unrecognized factors influencing cell culture.
 ...
PMID:The presence of transcription factors in fetal bovine sera. 954 56


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