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)

Intestinal trefoil factor (ITF) is an essential regulator of colonic epithelial restitution, the rapid migration of colonocytes over mucosal wounds. High levels of ITF are frequently present in colorectal cancers and derived cell lines. Mucosal restitution requires the detachment of epithelium from substrate, which would be expected to induce apoptosis. However, mice deficient in ITF showed an increase in colonocyte apoptosis unaccompanied by changes in expression of receptor-related (TNFR/Fas) or stress-related (Bcl-family) cell death regulators. An ITF-expressing colonic (HT-ITF1) cell line was resistant to apoptosis induced by serum starvation and ceramide. Exogenous ITF also protected another human colonic carcinoma-derived cell line (HCT116) and a nontransformed rat intestinal epithelial cell line (IEC-6) from apoptosis. This effect was abrogated by wortmannin and tyrphostin A25, indicating the potential involvement of phosphatidylinositol 3-kinase and epidermal growth factor (EGF) receptor activation. Expression of phosphorylated Akt, which lies downstream of phosphatidylinositol 3-kinase activation, was elevated in this HT-29-ITF line. p53-dependent cell death in the AGS human gastric cancer cell line after etoposide was similarly inhibited by transient expression of ITF but not a C-terminal truncation mutant of ITF, and it required functional phosphatidylinositol 3-kinase and EGF receptor. These findings support a central role for ITF in the maintenance of intestinal mucosal continuity, and conversely demonstrate the potential for ITF expression to confer resistance of colorectal tumors to therapy.
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PMID:Intestinal trefoil factor confers colonic epithelial resistance to apoptosis. 1063 60

We report on a patient with acute myeloid leukemia (AML M4) and a so far unrecorded translocation (17;19). The leukemia transformed from a myeloproliferative disorder (MPD) and showed a progressive fatal course. Following transformation, all leukemic cells showed an apparently balanced translocation (17;19)(p13;p13). The breakpoint regions harbor genes such as TP53 (17p13) and E2A, ENL, or LYL1 (19p13), which could be relevant in leukemogenesis. We suspect that the translocation (17;19)(p13;p13) may be a prognostic factor for transformation from chronic MPD to acute leukemia.
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PMID:A novel translocation (17;19)(p13;p13) in a patient with acute myelomonocytic leukemia. 1081 77

Human T-cell lymphotropic virus type 1 (HTLV-1) is associated with adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). T-cell transformation is mainly due to the actions of the viral phosphoprotein Tax. Tax interacts with multiple transcriptional factors, aiding the transcription of many cellular genes. Here, we report that the cyclin-dependent kinase inhibitor p21/waf1 is overexpressed in all HTLV-1-infected cell lines tested as well as in ATL and HAM/TSP patient samples. Tax was found to be able to transactivate the endogenous p21/waf1 promoter, as detected by RNase protection, as well as activate a series of wild-type and 5'-deletion constructs linked to a luciferase reporter cassette. Wild-type but not a mutant form of Tax (M47) transactivated the p21/waf1 promoter in a p53-independent manner and utilized a minimal promoter that contained E2A and TATA box sequences. The p21/waf1 protein was reproducibly observed to be complexed with cyclin A/cdk2 and not with any other known G(1), S, or G(2)/M cyclins. Functionally, the association of p21/cyclin A/cdk2 decreased histone H1 phosphorylation in vitro, as observed in immunoprecipitations followed by kinase assays, and affected other substrates, such as the C terminus of Rb protein involved in c-Abl and histone deacetylase-1 (HDAC1) regulation. Interestingly, upon the use of a stress signal, such as gamma-irradiation, we found that the p21/cyclin A/cdk2 complex was able to block all known phosphorylation sites on the Rb molecule. Finally, using elutriated cell cycle fractions and a stress signal, we observed that the HTLV-1-infected T cells containing wild-type Tax, which had been in early or mid-G(1) phase prior to gamma-irradiation, arrested in G(1) and did not undergo apoptosis. This may be an important mechanism for an oncogenic virus such as HTLV-1 to stop the host at the G(1)/S boundary and to repair the damaged DNA upon injury, prior to S-phase entry.
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PMID:Overexpression of p21(waf1) in human T-cell lymphotropic virus type 1-infected cells and its association with cyclin A/cdk2. 1090 81

By utilizing a human cDNA expression array blot (588 genes), we have observed overexpression of various transcription factors, cell cycle regulated kinases, and DNA repair genes in HTLV-1-infected T cells. One of the genes of interest, and focus in this study, is the cyclin-dependent kinase inhibitor, p21/waf1. The p21/waf1 transcription and protein is overexpressed in all HTLV-1-infected cell lines tested as well as ATL and HAM/TSP patient samples. While p21/waf1 has been shown to display a selectivity for G(1)/S cyclin/cdk complexes, we have observed p21/waf1 to be complexed with cyclin A/cdk2. Functionally, the association of p21/cyclin A/cdk2 decreased the histone H1 phosphorylation in vitro, as observed in immunoprecipitations followed by kinase assays, as well as affecting other substrates such as the C-terminus of Rb protein involved in c-Abl and HDAC1 regulation. Wild-type, but not a mutant form (M47) of Tax, was found to be able to transactivate the p21/waf1 promoter in a p53-independent manner. We found that the minimal p21/waf1 promoter (-49 to +49 sequence) was activated by Tax and the minimal promoter contained two E2A transcription factor binding sites located between the TATA box and the initiation site. E2A proteins, E12 and E47, as well as a related helix-loop-helix protein, HEB, are all up-regulated in HTLV-1-infected T cells. When using band shift analysis, we found that only the E1 site (overlapping the transcription start site) was a functional DNA binding site. By using a chromatin immunoprecipitation (ChIP) assay, we observed that histone H4, and not histone H3, was acetylated from the endogenous p21/waf1 promoter in vivo, implying that CBP/p300, and not the SAGA complex, was critical in complexing with E2A in up-regulation of p21/waf1 in HTLV-1-infected cells.
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PMID:Gene expression array of HTLV type 1-infected T cells: Up-regulation of transcription factors and cell cycle genes. 1108 Aug 12

Cellular differentiation entails the coordination of cell cycle arrest and tissue-specific gene expression. We investigated the involvement of basic helix-loop-helix (bHLH) factors in differentiation of osteoblasts using the human osteoblastic cell line MG63. Serum starvation induced growth arrest at G1 phase, accompanied by expression of cyclin-dependent kinase inhibitor p21(WAF1/Cip1). Reporter assays with the p21 gene promoter demonstrated that the combination of E2A (E12 or E47) and coactivator CBP was responsible for p21 induction independent of p53. Twist inhibited E2A-CBP-dependent activation of the exogenous and endogenous p21 promoters. Ids similarly inhibited the exogenously transfected p21 promoter; however less antagonistic effect on the endogenous p21 promoter was observed. Twist was predominantly present in nuclei in MG63 cells growing in complete medium, while it localized mainly in the cytoplasm after serum starvation. The fibroblast growth factor receptor 3 gene (FGFR3), which generates signals leading to differentiation of osteoblasts, was found to be controlled by the same transcriptional regulation as the p21 gene. E2A and Twist influenced alkaline phosphatase expression, a consensus marker of osteoblast differentiation. Expression of E2A and FGFR3 was seen at the location of osteoblast differentiation in the calvaria of mouse embryos, implicating bHLH molecules in physiological osteoblast differentiation. These results demonstrate that a common regulatory system is involved in at least two distinct steps in osteoblastic differentiation. Our results also provide the molecular basis of Saethre-Chotzen syndrome, caused by mutations of the TWIST and FGFR3 genes.
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PMID:Common regulation of growth arrest and differentiation of osteoblasts by helix-loop-helix factors. 1158 22

The responses of a line of normal human mammary epithelial cells, HME87, to treatment with the ultimate carcinogen benzo[a]pyrene diol epoxide (BPDE) were analyzed using a directed gene expression analysis technique, RAGE. Under conditions where cell number was decreased by 50% 24 or 48 h post-treatment, flow cytometry demonstrated no establishment of a G(1)/S arrest nor induction of apoptosis; cells continued to enter S phase from G(1) for at least 24 h but were blocked at G(2)/M. Using the RAGE technique, changes in gene expression were assayed for over 1000 genes, and multiple time-point data were collected for approximately 90 genes. In accord with the cell cycle studies, expression of the p21-WAF1 gene, the major mediator of p53-dependent G(1)/S arrest, did not increase until 24 h post-treatment. The expression of other target genes for transactivation by p53 was increased at early time points, including GADD45, an effector of the G(2)/M checkpoint, and WIP1. Analyses of proteins in treated cells indicated that p53 was phosphorylated at Ser15 but not at Ser20 within 30 min of treatment, and this correlated with an increase in the total amount of p53 protein. Significant expression changes were noted in a number of transcription factor genes, including ATF3 and E2A, genes that have not been previously connected to a response to DNA damage involving bulky chemical adducts. In addition, expression of the XPC gene was induced by BPDE treatment; the XPC product is thought to be involved in recognition of DNA damage by the nucleotide excision repair system.
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PMID:Response of human mammary epithelial cells to DNA damage induced by BPDE: involvement of novel regulatory pathways. 1258 71

Aberrant expression of tumor suppressor genes WT 1, RB 1, p53, homozygous deletion of p16 gene and their relationship with expression of oncogenes BCR-ABL, TEL-AML 1, MLL-AF 4, E2A-PBX 1, SIL-TAL 1 were determined in bone marrow samples of children with de novo B-lineage (n=170) and T-lineage (n=25) acute lymphoblastic leukemia (ALL). In contrast to expression of chimeric oncogenes alterations in p16, WT 1, RB 1 and p53 expression were T/B-lineage-unrestricted. Significant association between expression of MLL-AF 4 and WT 1, E2A-PBX 1 and p53; SIL-TAL 1 and homozygous deletion of p16 has been demonstrated.
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PMID:Aberrant expression of tumor suppressor genes and their association with chimeric oncogenes in pediatric acute lymphoblastic leukemia. 1587 20

The E-protein transcription factors E2A, HEB, and E2-2 play an essential role in the differentiation, proliferation, and survival of B lymphocyte progenitors (BLPs). In this study, we show that the E-protein antagonist Id3 induces apoptosis of both primary and transformed BLPs through a caspase-2-dependent mechanism that does not require p53 and is not inhibited by bcl-2. Id3 expressing B lineage cells show reduced expression of known E-protein target genes as well as multiple genes involved in cell proliferation. We hypothesize that Id3 induces activation of caspase-2 as a consequence of severe or "catastrophic" growth arrest. In support of this hypothesis, we show that chemical-induced growth arrest is sufficient to activate caspase-2 and induce apoptosis in BLPs. Our data suggest that E-proteins function in the control of differentiation and proliferation and that diminished E-protein activity results in apoptosis as a consequence of growth arrest.
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PMID:Id3 induces growth arrest and caspase-2-dependent apoptosis in B lymphocyte progenitors. 1617 95

Loss of E2A transcription factor activity or activation of the intracellular form of Notch1 (ICN) leads to the development of leukemia or lymphoma in humans or mice, respectively. Current models propose that ICN functions by suppressing E2A through a pre-T cell receptor (TCR)-dependent mechanism. Here we show that lymphomas arising in E2A(-/-) mice require the activation of Notch1 for their survival and have accumulated mutations in, or near, the Notch1 PEST domain, resulting in increased stability and signaling. In contrast, lymphomas arising in p53(-/-) mice show the activation of Notch1, but no mutations were identified in ICN. The requirement for Notch1 signaling in E2A(-/-) lymphomas cannot be overcome by ectopic expression of pTalpha; however, pTalpha is required for optimal survival and expansion of these cells. Our findings indicate that the activation of Notch1 is an important "second hit" for the transformation of E2A(-/-) T cell lymphomas and that Notch1 promotes survival through pre-TCR-dependent and -independent mechanisms.
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PMID:Notch1 promotes survival of E2A-deficient T cell lymphomas through pre-T cell receptor-dependent and -independent mechanisms. 1644 26

Toll-like receptors (TLRs) are important sensors of microbial pathogens and mediators of innate immune responses. Although the signal transduction of TLRs is well elucidated, their basal regulation is largely unexplored. Here we show that the tumor suppressor p53 positively regulates the transcription of TLR3, a receptor for viral double-stranded RNA and poly(I-C), by binding to the p53 site in the TLR3 promoter. TLR3 expression was lower in HCT116 p53(-/-) cells than in HCT116 p53(+/+) cells. Activation of p53 by 5-fluorouracil increased the TLR3 mRNA in epithelial cell lines with wild-type p53 but not in cell lines harboring mutant p53. Knockdown of p53 by small interfering RNA decreased the TLR3 expression. TLR3 mRNA was also lower in liver and intestine of p53(-/-) mice than in p53(+/+) mice. Furthermore, the poly(I-C)-induced phosphorylation of IkappaB-alpha, nuclear translocation of NF-kappaB, and phosphorylation of interferon regulatory transcription factor 3, were drastically reduced in HCT116 p53(-/-) cells, indicating a dysregulation of the two signaling pathways governed by TLR3. Consequently, induction of interleukin-8 and beta interferon after poly(I-C) stimulation was impaired in HCT116 p53(-/-) cells. These results suggest that p53 influences TLR3 expression and function and highlight a role of p53 in innate immune response in epithelial cells.
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PMID:p53 regulates Toll-like receptor 3 expression and function in human epithelial cell lines. 1877 17


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