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)

The tetramerization domain of p53 is required for efficient tumor suppressor activity. This domain, however, also allows wild-type p53 to heterooligomerize with dominant negative tumor-derived p53 mutants. We explored the feasibility of substituting the native tetramerization domain of wild-type p53 with an engineered leucine zipper that assembles as a four-stranded coiled coil. The engineered zipper drove p53 tetramerization in vitro and p53 function in vivo. Furthermore, it alleviated transdominant inhibition by tumor-derived p53 mutants, implying that dominant negative mutants act by hetero-oligomerizing with wild-type p53. The ability of the engineered zipper to drive tetramerization was critical for p53 function, since p53 dimers, formed by substituting the p53 tetramerization domain with a native leucine zipper, were weak tumor suppressors.
 ...
PMID:An engineered four-stranded coiled coil substitutes for the tetramerization domain of wild-type p53 and alleviates transdominant inhibition by tumor-derived p53 mutants. 854 57

The E2A-HLF (for hepatic leukaemia factor) fusion gene, formed by action of the t(17;19) (q22;p13) chromosomal translocation, drives the leukaemic transformation of early B-cell precursors, but the mechanism of this activity remains unknown. Here we report that human leukaemia cells carrying the translocation t(17;19) rapidly died by apoptosis when programmed to express a dominant-negative suppressor of the fusion protein E2A-HLF, indicating that the chimaeric oncoprotein probably affects cell survival rather than cell growth. Moreover, when introduced into murine pro-B lymphocytes, the oncogenic E2A-HLF fusion protein reversed both interleukin-3-dependent and p53-mediated apoptosis. The close homology of the basic region/leucine zipper (bZIP) DNA-binding and dimerization domain of HLF to that of the CES-2 cell-death specification protein of Caenorhabditis elegans suggests a model of leukaemogenesis in which E2A-HLF blocks an early step within an evolutionarily conserved cell-death pathway.
 ...
PMID:Reversal of apoptosis by the leukaemia-associated E2A-HLF chimaeric transcription factor. 870 Feb 28

The hepatitis B virus-encoded protein, HBx, may contribute to carcinogenesis by perturbing cell growth and differentiation. There is some evidence indicating that HBx represses the nuclear import of the tumour repressor p53 and p53-dependent trans-activation and that HBx activates members of the basic region-leucine zipper (bZIP) family.
 ...
PMID:Hepatitis B virus-induced hepatocellular carcinoma: possible roles for HBx. 882 35

CHOP (GADD153) is a member of the C/EBP family and a stress-induced protein. To investigate the role of CHOP in cellular growth, we expressed CHOP conditionally in M1 myeloblastic leukemia cells that do not express p53 protein. More than 60% of M1 cells died through apoptosis 72 h after CHOP induction. Site-directed mutagenesis revealed that this process requires leucine zipper domain but neither intact basic region nor trans-activation domain. CHOP-mediated apoptosis accompanied downregulation of bcl-2 mRNA and overexpression of Bcl-2 delayed the process. Our results indicate that CHOP can induce apoptosis in a p53-independent manner.
 ...
PMID:Ectopic expression of CHOP (GADD153) induces apoptosis in M1 myeloblastic leukemia cells. 889 82

The Epstein-Barr virus (EBV) immediate early transactivator Zta is a basic leucine zipper (bZIP) transcription factor that causes G0/G1 cell cycle arrest through induction of the tumor suppressor protein, p53, and the cyclin-dependent kinase inhibitors, p21 and p27 (Cayrol, C., and Flemington, E. K. (1996) EMBO J. 15, 2748-2759). Here, we report a genetic analysis of Zta-mediated G0/G1 growth arrest and p21 induction. The majority of the Zta transactivation domain can be deleted (ZDelta1-128) without significantly affecting the ability of Zta to elicit growth arrest. A larger amino-terminal deletion (ZDelta1-167) abrogates the ability of Zta to inhibit proliferation, mapping the growth-inhibitory domain to a carboxyl-terminal region encompassing the bZIP domain (amino acids 128-245). The integrity of the bZIP domain is required for growth suppression since a two-amino acid mutant which is defective for homodimerization, fails to induce cell cycle arrest. Western blot analysis of p21 expression in cells expressing Zta mutants reveals that the ability of Zta mutants to cause G0/G1 growth arrest is intimately related to their capacity to induce p21 expression. Together, these data demonstrate that a carboxyl-terminal region of Zta that includes the bZIP domain is sufficient to mediate G0/G1 growth arrest and p21 induction.
 ...
PMID:G0/G1 growth arrest mediated by a region encompassing the basic leucine zipper (bZIP) domain of the Epstein-Barr virus transactivator Zta. 894 19

Upstream stimulating factor (USF2) is a basic helix-loop-helix leucine zipper transcription factor, which is found in most tissues. A critical role for USF2 in cellular proliferation has been proposed based on its importance in the regulation of various cyclins and P53 and its capability to antagonize c-myc. In this paper we report that IL-3, which is a major growth factor for mast cells, induces USF2 protein synthesis in murine mast cells (MC-9). Surprisingly, it does not significantly affect the level of USF2 mRNA in these cells at any of the time points tested. Using polysomal fractionation and RNA analysis we then demonstrated that this translational regulation is mostly the result of increased USF2 translational efficiency. Moreover, protein kinase C (PKC) inhibitors prevented both the induction of USF2 protein synthesis and the increase in USF2 translational efficiency in IL-3-activated mast cells. Two other hematopoietic cell lines were used to determine whether the translational regulation of USF2 is of a more general nature: mouse lymphosarcoma cells whose proliferation is inhibited by dexamethasone; and mouse erythroleukemia cells that differentiate upon exposure to hexamethylen bisacetamide. In both cell types, USF2 translation was repressed in the non-dividing cells. This strongly implies that USF2 is translationally repressed in quiescent hematopoietic cells. Considering the proposed role of USF in proliferation it seems that translational regulation of USF2 might have an important role in cellular growth.
 ...
PMID:Growth-dependent and PKC-mediated translational regulation of the upstream stimulating factor-2 (USF2) mRNA in hematopoietic cells. 948 40

The Drosophila Groucho (Gro) protein is a corepressor required by a number of DNA-binding transcriptional repressors. Comparison of Gro with its homologues in other eukaryotic organisms reveals that Gro contains, in addition to a conserved C-terminal WD repeat domain, a conserved N-terminal domain, which has previously been implicated in transcriptional repression. We determined, via a variety of hydrodynamic measurements as well as protein cross-linking, that native Gro is a tetramer in solution and that tetramerization is mediated by two putative amphipathic alpha-helices (termed leucine zipper-like motifs) found in the N-terminal region. Point mutations in the leucine zipper-like motifs that block tetramerization also block repression by Gro, as assayed in cultured Drosophila cells with Gal4-Gro fusion proteins. Furthermore, the heterologous tetramerization domain from p53 fully substitutes for the Gro tetramerization domain in transcriptional repression. These findings suggest that oligomerization is essential for Gro-mediated repression and that the primary function of the conserved N-terminal domain is to mediate this oligomerization.
 ...
PMID:A role for Groucho tetramerization in transcriptional repression. 981 12

The human genetic disorder ataxia-telangiectasia (AT) is characterized by immunodeficiency, progressive cerebellar ataxia, radiosensitivity, cell cycle checkpoint defects and cancer predisposition. The gene mutated in this syndrome, ATM (for AT mutated), encodes a protein containing a phosphatidyl-inositol 3-kinase (PI-3 kinase)-like domain. ATM also contains a proline-rich region and a leucine zipper, both of which implicate this protein in signal transduction. The proline-rich region has been shown to bind to the SH3 domain of c-Abl, which facilitates its phosphorylation and activation by ATM. Previous results have demonstrated that AT cells are defective in the G1/S checkpoint activated after radiation damage and that this defect is attributable to a defective p53 signal transduction pathway. We report here direct interaction between ATM and p53 involving two regions in ATM, one at the amino terminus and the other at the carboxy terminus, corresponding to the PI-3 kinase domain. Recombinant ATM protein phosphorylates p53 on serine 15 near the N terminus. Furthermore, ectopic expression of ATM in AT cells restores normal ionizing radiation (IR)-induced phosphorylation of p53, whereas expression of ATM antisense RNA in control cells abrogates the rapid IR-induced phosphorylation of p53 on serine 15. These results demonstrate that ATM can bind p53 directly and is responsible for its serine 15 phosphorylation, thereby contributing to the activation and stabilization of p53 during the IR-induced DNA damage response.
 ...
PMID:ATM associates with and phosphorylates p53: mapping the region of interaction. 984 17

The purpose of this review is to discuss ATF3, a member of the ATF/CREB family of transcription factors, and its roles in stress responses. In the introduction, we briefly describe the ATF/CREB family, which contains more than 10 proteins with the basic region-leucine zipper (bZip) DNA binding domain. We summarize their DNA binding and heterodimer formation with other bZip proteins, and discuss the nomenclature of these proteins. Over the years, identical or homologous cDNA clones have been isolated by different laboratories and given different names. We group these proteins into subgroups according to their amino acid similarity; we also list the alternative names for each member, and clarify some potential confusion in the nomenclature of this family of proteins. We then focus on ATF3 and its potential roles in stress responses. We review the evidence that the mRNA level of ATF3 greatly increases when the cells are exposed to stress signals. In animal experiments, the signals include ischemia, ischemia coupled with reperfusion, wounding, axotomy, toxicity, and seizure; in cultured cells, the signals include serum factors, cytokines, genotoxic agents, cell death-inducing agents, and the adenoviral protein E1A. Despite the overwhelming evidence for its induction by stress signals, not much else is known about ATF3. Preliminary results suggest that the JNK/SAPK pathway is involved in the induction of ATF3 by stress signals; in addition, IL-6 and p53 have been demonstrated to be required for the induction of ATF3 under certain conditions. The consequences of inducing ATF3 during stress responses are not clear. Transient transfection and in vitro transcription assays indicate that ATF3 represses transcription as a homodimer; however, ATF3 can activate transcription when coexpressed with its heterodimeric partners or other proteins. Therefore, it is possible that, when induced during stress responses, ATF3 activates some target genes but represses others, depending on the promoter context and cellular context. Even less is understood about the physiological significance of inducing ATF3. We will discuss our preliminary results and some reports by other investigators in this regard.
 ...
PMID:ATF3 and stress responses. 1044 Feb 33

The cell cycle inhibitor protein p21(WAF1/Cip1) (p21) is a critical downstream effector in p53-dependent mechanisms of growth control and p53-independent pathways of terminal differentiation. We have recently reported that the transforming growth factor-beta pathway-specific Smad3 and Smad4 proteins transactivate the human p21 promoter via a short proximal region, which contains multiple binding sites for the ubiquitous transcription factor Sp1. In the present study we show that the Sp1-occupied promoter region mediates transactivation of the p21 promoter by c-Jun and the related proteins JunB, JunD, and ATF-2. By using gel electrophoretic mobility shift assays we show that this region does not contain a binding site for c-Jun. In accordance with the DNA binding data, c-Jun was unable to transactivate the p21 promoter when overexpressed in the Sp1-deficient Drosophila-derived SL2 cells. Coexpression of c-Jun and Sp1 in these cells resulted in a strong synergistic transactivation of this promoter. In addition, a chimeric promoter consisting of six tandem high affinity Sp1-binding sites fused with the CAT gene was transactivated by overexpressed c-Jun in HepG2 cells. The above data propose functional cooperation between c-Jun and Sp1. Physical interactions between the two factors were demonstrated in vitro by using GST-Sp1 hybrid proteins expressed in bacteria and in vitro transcribed-translated c-Jun. The region of c-Jun mediating interaction with Sp1 was mapped within the basic region leucine zipper domain. In vivo, functional interactions between c-Jun and Sp1 were demonstrated using a GAL4-based transactivation assay. Overexpressed c-Jun transactivated a chimeric promoter consisting of five tandem GAL4-binding sites only when coexpressed with GAL4-Sp1-(83-778) fusion proteins in HepG2 cells. By utilizing the same assay, we found that the glutamine-rich segment of the B domain of Sp1 (Bc, amino acids 424-542) was sufficient for c-Jun-induced transactivation of the p21 promoter. In conclusion, our data support a mechanism of superactivation of Sp1 by c-Jun, which is based on physical and functional interactions between these two transcription factors on the human p21 and possibly other Sp1-dependent promoters.
 ...
PMID:c-Jun transactivates the promoter of the human p21(WAF1/Cip1) gene by acting as a superactivator of the ubiquitous transcription factor Sp1. 1050 25


1 2 3 4 5 Next >>