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)

For cancer gene therapy, a recombinant adenovirus serotype 5 named RPR/INGN201 has been constructed by susbtitution of the E1 region with human tumor suppressor gene p53. The protein components of RPR/INGN201 virions were separated by reversed-phase HPLC and were individually identified by electrospray time-of-flight mass spectrometry and N-terminal sequencing, both on intact proteins and on their proteolytic fragments after trypsin digestion. Twenty-five peptide components of the proteome (including fiber) with greater than 0.25-0.5% contribution to the protein content of the virus were identified and characterized. Fiber was confirmed to be partially glycosylated (both the non-glycosylated and the monoglycosylated states were identified), and two proteins were isolated and identified as phosphorylation derivatives, namely protein V (non-phosphorylated and monophosphorylated) and protein IIIa (mono- and diphosphorylated). This new analytical tool proved to be very useful not only for refining our current knowledge of the polypeptide repertoire of purified infectious virions but also for monitoring and very rapidly identifying structural modifications resulting from changes in the manufacturing process. It was also used successfully for the characterization of various adenoviral constructs.
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PMID:Polypeptide composition of an adenovirus type 5 used in cancer gene therapy. 1146 Oct 12

We have previously shown that the pharmacological agents 4-(2-aminoethyl)=benzenesulfonylfluoride hydrochloride (AEBSF) and Na-p-tosyl-L-lysine chloromethylketone (TLCK), inhibitors of trypsin-like serine proteases, prevent the death of trophic factor-deprived PC12 cells and sympathetic neurons. Both AEBSF and TLCK inhibit caspase activation in this model, but it is unclear whether they do so indirectly or through a direct effect at the level of the caspases. In the current study, we have used these agents in another model of neuronal death that is induced by DNA damage. We find that both agents delay the death of DNA-damaged PC12 cells, neonatal rat sympathetic neurons and embryonic rat cortical neurons. As in the trophic deprivation model, they act upstream of the caspases. In addition, they prevent mitochondrial alterations, such as cytochrome c release or loss of transmembrane potential. In contrast, the general caspase inhibitor bok-asp-fmk does not prevent cytochrome c release and has only a partial and transient effect on loss of transmembrane potential. Interestingly, both AEBSF and TLCK prevent the induction and nuclear accumulation of p53 that is induced by DNA damage in cortical neurons. Therefore, these serine protease inhibitors act at a point upstream in the apoptotic pathway, prior to p53 induction and the mitochondrial checkpoint, to delay neuronal death in this model, and do not act at the level of the caspases. We conclude that therapeutic strategies based on serine protease inhibition may be useful in preventing neuronal cell death.
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PMID:Inhibitors of trypsin-like serine proteases prevent DNA damage-induced neuronal death by acting upstream of the mitochondrial checkpoint and of p53 induction. 1173 Nov 8

Helical peptides that can intervene and disrupt therapeutically important protein-protein interactions are attractive drug targets. In order to develop a general strategy for developing such helical peptide mimics, we have studied the effect of incorporating alpha-amino isobutyric acid (Aib), an amino acid with strong preference for helical backbone, as the sole helix promoter in designed peptides. Specifically, we focus on the hdm2-p53 interaction, which is central to development of many types of cancer. The peptide corresponding to the hdm2 interacting part of p53, helical in bound state but devoid of structure in solution, served as the starting point for peptide design that involved replacement of noninteracting residues by Aib. Incorporation of Aib, while preserving the interacting residues, led to significant increase in helical structure, particularly at the C-terminal region as judged by nuclear magnetic resonance and circular dichroism. The interaction with hdm2 was also found to be enhanced. Most interestingly, trypsin cleavage was found to be retarded by several orders of magnitude. We conclude that incorporation of Aib is a feasible strategy to create peptide helical mimics with enhanced receptor binding and lower protease cleavage rate.
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PMID:Aib-based peptide backbone as scaffolds for helical peptide mimics. 1210 21

Rare pancreatic endocrine tumors consisting of both exocrine and endocrine components have been reported sporadically. We investigated the ductal and acinar differentiation in pancreatic endocrine tumors. In immunohistochemical studies of 28 pancreatic endocrine tumors, staining with anti-carcinoembryonic antigen (CEA) or CA19-9 antibody indicated ductal differentiation, while staining with anti-amylase or anti-trypsin antibody indicated acinar differentiation. K-ras gene mutations and p53 gene alterations also were studied. Ten tumors were immunoreactive for CEA or CA19-9. Five tumors diffusely immunoreactive for CEA or CA19-9, in addition to endocrine markers, were diagnosed as duct-endocrine cell tumors of the pancreas. Two tumors diffusely immunoreactive for CEA or CA19-9 and also for pancreaticogut hormones as well as endocrine markers were diagnosed as duct-acinarendocrine cell tumors. These tumors showed uniform histologic features and synchronous ductal, acinar, and endocrine differentiation, distinct from the coexisting different cellular populations seen in collision tumors. All tumors were malignant. These duct-endocrine cell tumors or duct-acinar- endocrine cell tumors of the pancreas may be derived from a stem cell that retains the capability of expressing either an exocrine or endocrine phenotype. Only one K-ras gene mutation and no p53 gene alterations were detected in these tumors, which suggests that they constitute an entity with a different origin than ductal carcinomas.
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PMID:Ductal and acinar differentiation in pancreatic endocrine tumors. 1239 98

Mast cells with bilobed or multilobed nuclei have only rarely been observed in the bone marrow of patients with systemic mastocytosis and in a case of subdural mast cell sarcoma. To our knowledge, they have not been reported in cutaneous mast cell disease. We report a rare occurrence of mast cells with bilobed or multilobed nuclei (atypical mast cell type II) in a nodular lesion of a 24-year-old woman with urticaria pigmentosa. The typical and atypical mast cells were confirmed by Giemsa and Leder's naphthol-AS-D-chloroacetate esterase stains and by immunohistochemical staining for tryptase and KIT protein (CD117). Although the nodular lesion with atypical mast cells did not appear to be cytologically malignant, the occurrence of atypical mast cells in a nodular lesion but not in a papular lesion might denote progression of the disease as suggested by the emergence of cells positive for p53.
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PMID:Mast cells with bilobed or multilobed nuclei in a nodular lesion of a patient with urticaria pigmentosa. 1245 1

A novel fluorescent substrate was devised for the sirtuin (SIRT) class of human protein deacetylases comprised of a peptide sequence containing a single acetyl-lysine residue, with a fluorescent group (tetramethylrhodamine-6-carboxylic acid, 6-TAMRA) near the carboxyl terminus and a nonfluorescent quenching group (QSY-7) near the amino terminus. The peptide sequence is modeled after the p53 acetylation site but is unreactive toward trypsin because all other lysine and arginine residues have been replaced by serine. However, the SIRT-deacetylated peptide is readily cleaved by trypsin, resulting in a maximal 30-fold enhancement of the 6-TAMRA fluorescence. Nicotinamide at millimolar concentrations stops the deacetylation but does not inhibit trypsin, and a microtiter plate assay of the SIRTs has been devised using the fluorescent substrate and these reagents. Using this method, the kinetics of the reaction of the cosubstrate nicotinamide adenine dinucleotide and the competitive inhibitor nicotinamide with SIRT1 and SIRT2 has been analyzed. Several nicotinamide analogs have also been tested as inhibitors and found to have much lower affinity for these enzymes than does the parent compound.
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PMID:Fluorescence assay of SIRT protein deacetylases using an acetylated peptide substrate and a secondary trypsin reaction. 1530 53

We compared the clinicopathological features of acinar-cell carcinomas (ACCs) with those of mixed acinar-endocrine carcinomas (MAECs). Specimens from 37 patients with ACC and 6 patients with MAEC were examined histologically and immunohistochemically. The mean age of ACC and MAEC patients was similar (61.3 years versus 58.4 years), but the sex ratio differed (ACC, 29 males and 8 females; MAEC, 2 males and 4 females). The size of the tumor was large in both cases (ACC, 13.8 cm in diameter; MAEC, 8.2 cm). Immunohistochemically, more than half of the tumor cells in all tumors, whether ACC or MAEC, stained for trypsin. In 20 of the 37 ACCs (54%), scattered endocrine cells (SECs) were found, which stained positively for synaptophysin (SYN) and/or chromogranin A (CGA). Interestingly, there was also a difference in the sex ratio between ACC patients without SECs (16 males and 1 female) and ACC patients with SECs (13 males and 7 females). In MAECs, the cells staining for SYN were more common than those staining for CGA and made up more than one-third of the neoplastic-cell population. In all but one case (in which the endocrine component was arranged in islet-like cell clusters), the endocrine cells were intimately mixed with trypsin-positive tumor cells. The endocrine cells only rarely expressed one of the known pancreatic or gastrointestinal hormones. Both ACCs and MAECs had a high proliferation rate and lacked p53 overexpression or progesterone and estrogen receptors. This study revealed that ACCS and MAECs share most clinicopathological features and, therefore, may form a single tumor entity, though they differ in the number of endocrine cells. The frequent identification of endocrine cells in these tumors suggests the existence of a pluripotent cell of origin that is capable of differentiating into acinar and endocrine cells.
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PMID:Mixed acinar-endocrine carcinoma of the pancreas. A clinicopathological study and comparison with acinar-cell carcinoma. 1551 67

Tumor suppressor p53 induces apoptosis through the transactivation of target genes. Previous work has shown that p53-dependent gene expression changes in response to ionizing radiation are tissue specific. To determine critical p53 target genes in the colon, we irradiated wild-type and p53-null mice and examined the global p53 gene expression patterns in response to ionizing radiation. Microarray analysis using the Affymetrix MOE430A genechip showed that many of the genes that increased in a p53-dependent manner are serine proteases (e.g., elastase, trypsin) and other proteases (e.g., carboxypeptidases). Reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry, and Western blots were used to validate microarray results on trypsin 4, carboxypeptidase A1, and elastase-2, three genes that have potential p53-binding elements. Further study of tissue specific mediators of p53-dependent responses such as serine proteases will greatly increase understanding of in vivo p53-dependent pathways within the colon triggered by ionizing radiation.
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PMID:p53-dependent induction of serine proteases in irradiated mouse colon. 1568 11

Ubiquitin-mediated proteolysis plays a central role in controlling intracellular levels of essential regulatory molecules such as p53, cyclins, myc, BRCA1, HIF-1alpha, etc. The Kruppel-like factor 5 (KLF5) transcription factor regulates biological processes involved in carcinogenesis, angiogenesis, and smooth muscle cell differentiation. In carcinogenesis, KLF5's role has been indicated by frequent genetic deletion as well as functional studies. Here we show that KLF5 is an unstable protein with a short half-life. Destruction of KLF5 was prevented by each of the proteasome-specific inhibitors tested but not by an inhibitor for trypsin-like proteases and cysteine proteases or by a lysosome inhibitor in epithelial cells. Furthermore, KLF5 underwent ubiquitination, and deletion of a 56-amino-acid sequence adjacent to a known transactivation domain of KLF5 significantly reduced its ubiquitination and degradation. Interestingly, cancer cells appeared to be more active in KLF5 degradation than untransformed epithelial cells, yet their proteasome activity was not higher. These results suggest that KLF5 protein is degraded at least in part through ubiquitination-proteasome pathway, which may have become hyperactive for KLF5 in cancer cells.
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PMID:Ubiquitin-proteasome degradation of KLF5 transcription factor in cancer and untransformed epithelial cells. 1573 97

The proteasome is the main protease for extralysosomal protein degradation in eukaryotic cells, and constitutes a sophisticated high molecular mass proteinase complex underlying a tightly coordinated expression and assembly of multiple subunits and subcomplexes. Here we show that continuous inhibition of proteasomal chymotrypsin-like peptidase activity by the proteasome inhibitor bortezomib induces in human Namalwa Burkitt lymphoma cells increased de novo biogenesis of proteasomes accompanied by increased expression of the proteasome maturation protein POMP, increased expression of 19S-20S-19S proteasomes, and abrogation of expression of beta 1i, beta 2i and beta 5i immunosubunits and PA28 in favor of increased expression of constitutive proteolytic beta1, beta2 and beta 5 subunits and 19S regulatory complexes. These alterations of proteasome expression and subunit composition are accompanied by an increase in proteasomal caspase-like, trypsin-like and chymotrypsin-like peptidase activities, not inhibitable by high doses of bortezomib. Cells harboring these proteasomal alterations display rapid proliferation and cell cycle progression, and acquire resistance to apoptosis induced by proteasome inhibitors, gamma-irradiation and staurosporine. This acquired apoptosis resistance is accompanied by de novo expression of anti-apoptotic Hsp27 protein and the loss of ability to accumulate and stabilize pro-apoptotic p53 protein. Thus, increased expression, altered subunit composition and increased activity of proteasomes constitute a hitherto unknown adaptive and autoregulatory feedback mechanism to allow cells to survive the lethal challenge of proteasome inhibition and to establish a hyperproliferative and apoptosis-resistant phenotype.
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PMID:Increased expression and altered subunit composition of proteasomes induced by continuous proteasome inhibition establish apoptosis resistance and hyperproliferation of Burkitt lymphoma cells. 1751 11


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