共查询到20条相似文献,搜索用时 31 毫秒
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The p16INK4a tumor suppressor controls p21WAF1 induction in response to ultraviolet light 总被引:1,自引:0,他引:1
p16INK4a and p21WAF1, two major cyclin-dependent kinase inhibitors, are the products of two tumor suppressor genes that play important roles in various cellular metabolic pathways. p21WAF1 is up-regulated in response to different DNA damaging agents. While the activation of p21WAF1 is p53-dependent following γ-rays, the effect of ultraviolet (UV) light on p21WAF1 protein level is still unclear. In the present report, we show that the level of the p21WAF1 protein augments in response to low UVC fluences in different mammalian cells. This up-regulation is mediated through the stabilization of p21WAF1 mRNA in a p16INK4a-dependent manner in both human and mouse cells. Furthermore, using p16-siRNA treated human skin fibroblast; we have shown that p16 controls the UV-dependent cytoplasmic accumulation of the mRNA binding HuR protein. In addition, HuR immunoprecipitations showed that UV-dependent binding of HuR to p21 mRNA is p16-related. This suggests that p16 induces p21 by enabling the relocalization of HuR from the nucleus to the cytoplasm. Accordingly, we have also shown that p16 is necessary for efficient UV-dependent p53 up-regulation, which also requires HuR. These results indicate that, in addition to its role in cell proliferation, p16INK4a is also an important regulator of the cellular response to UV damage. 相似文献
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Xiao Fang Guojun Lu Kyungsoo Ha Han Lin Ye Du Qiuhong Zuo Yi Fu Chaoxia Zou Pumin Zhang 《Experimental cell research》2018,362(2):279-286
Tumor cells often encounter hypoglycemic microenvironment due to rapid cell expansion. It remains elusive how tumors reprogram the genome to survive the metabolic stress. The tumor suppressor TIP60 functions as the catalytic subunit of the human NuA4 histone acetyltransferase (HAT) multi-subunit complex and is involved in many different cellular processes including DNA damage response, cell growth and apoptosis. Attenuation of TIP60 expression has been detected in various tumor types. The function of TIP60 in tumor development has not been fully understood. Here we found that suppressing TIP60 inhibited p53 K120 acetylation and thus rescued apoptosis induced by glucose deprivation in hepatocellular cancer cells. Excitingly, Lys-104 (K104), a previously identified lysine acetylation site of TIP60 with unknown function, was observed to be indispensable for inducing p53-mediated apoptosis under low glucose condition. Mutation of Lys-104 to Arg (K104R) impeded the binding of TIP60 to human NuA4 complex, suppressed the acetyltransferase activity of TIP60, and inhibited the expression of pro-apoptotic genes including NOXA and PUMA upon glucose starvation. These findings demonstrate the critical regulation of TIP60/p53 pathway in apoptosis upon metabolic stress and provide a novel insight into the down-regulation of TIP60 in tumor cells. 相似文献
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Over-expression of the human MDM2 p53 binding domain by fusion to a p53 transactivation peptide 总被引:1,自引:0,他引:1
MDM2 binds to the tumor suppressor protein p53 and regulates the level of p53 in cells. Although it is possible to prepare a small amount of the region of MDM2 that binds to p53, the expression level of this fragment of MDM2 is relatively low, limiting the studies involving this protein. Here, we describe a construct for the optimized bacterial expression and purification of the MDM2 p53 binding domain. We found that the expression level of the soluble MDM2 p53 binding domain in bacteria was increased dramatically by fusing it to its interaction partner, the p53 transactivation peptide. Attachment of the p53 transactivation peptide (residues 17-29) to the N-terminus of MDM2 resulted in a more than 200-fold increase of soluble protein expression of the p53 binding domain in bacteria. To obtain the final MDM2 p53 binding domain (residues 5-109) we inserted a tobacco etch virus protease recognition site between the P53 peptide and the MDM2 p53 binding domain. To weaken the protein/peptide interaction and facilitate the separation of the protein from the complex, we introduced a point mutation of one of the key interaction residues (F19A or W23A) in the p53 peptide. The advantages of our new construct are high yield and easy purification of the MDM2 protein. 相似文献
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Tawnya M. Webber 《Biochemical and biophysical research communications》2009,384(1):66-12658
The p53 tumor suppressor protein is a critical checkpoint in prevention of tumor formation, and the function of p53 is dependent on proper formation of the active tetramer. In vitro studies have shown that p53 binds DNA most efficiently as a tetramer, though inactive p53 is predicted to be monomeric in vivo. We demonstrate that FlAsH binding can be used to distinguish between oligomeric states of p53, providing a potential tool to explore p53 oligomerization in vivo. The FlAsH tetra-cysteine binding motif has been incorporated along the dimer and tetramer interfaces in the p53 tetramerization domain to create reporters for the dimeric and tetrameric states of p53, though the geometry of the four cysteines is critical for efficient FlAsH binding. Furthermore, we demonstrate that FlAsH binding can be used to monitor tetramer formation in real-time. These results demonstrate the potential for using FlAsH fluorescence to monitor protein-protein interactions in vivo. 相似文献
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Qian Cheng Tanjing Song Lihong Chen Jiandong Chen 《Molecular and cellular biology》2014,34(15):2800-2810
The RING domain ubiquitin E3 ligase MDM2 is a key regulator of p53 degradation and a mediator of signals that stabilize p53. The current understanding of the mechanisms by which MDM2 posttranslational modifications and protein binding cause p53 stabilization remains incomplete. Here we present evidence that the MDM2 central acidic region is critical for activating RING domain E3 ligase activity. A 30-amino-acid minimal region of the acidic domain binds to the RING domain through intramolecular interactions and stimulates the catalytic function of the RING domain in promoting ubiquitin release from charged E2. The minimal activation sequence is also the binding site for the ARF tumor suppressor, which inhibits ubiquitination of p53. The acidic domain-RING domain intramolecular interaction is modulated by ATM-mediated phosphorylation near the RING domain or by binding of ARF. These results suggest that MDM2 phosphorylation and association with protein regulators share a mechanism in inhibiting the E3 ligase function and stabilizing p53 and suggest that targeting the MDM2 autoactivation mechanism may be useful for therapeutic modulation of p53 levels. 相似文献
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Wölcke J Reimann M Klumpp M Göhler T Kim E Deppert W 《The Journal of biological chemistry》2003,278(35):32587-32595
The concept that the tumor suppressor p53 is a latent DNA-binding protein that must become activated for sequence-specific DNA binding recently has been challenged, although the "activation" phenomenon has been well established in in vitro DNA binding assays. Using electrophoretic mobility shift assays and fluorescence correlation spectroscopy, we analyzed the binding of "latent" and "activated" p53 to double-stranded DNA oligonucleotides containing or not containing a p53 consensus binding site (DNAspec or DNAunspec, respectively). In the absence of competitor DNA, latent p53 bound DNAspec and DNAunspec with high affinity in a sequence-independent manner. Activation of p53 by the addition of the C-terminal antibody PAb421 significantly decreased the binding affinity for DNAunspec and concomitantly increased the binding affinity for DNAspec. The net result of this dual effect is a significant difference in the affinity of activated p53 for DNAspec and DNAunspec, which explains the activation of p53. High affinity nonspecific DNA binding of latent p53 required both the p53 core domain and the p53 C terminus, whereas high affinity sequence-specific DNA binding of activated p53 was mediated by the p53 core domain alone. The data suggest that high affinity nonspecific DNA binding of latent and high affinity sequence-specific binding of activated p53 to double-stranded DNA differ in their requirement for the C terminus and involve different structural features of the core domain. Because high affinity nonspecific DNA binding of latent p53 is restricted to wild type p53, we propose that it relates to its tumor suppressor functions. 相似文献
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p53 C-terminal interaction with DNA ends and gaps has opposing effect on specific DNA binding by the core 总被引:1,自引:1,他引:0
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In addition to binding DNA in a sequence-specific manner, the p53 tumour suppressor protein can interact with damaged DNA. In order to understand which structural features in DNA the C-teminal domain recognises we have studied the interaction of p53 protein with different types of DNA oligonucleotides imitating damaged DNA. Here we show that one unpaired nucleotide within double-stranded (ds)DNA is sufficient for recognition by the p53 C-terminus, either as a protruding end or as an internal gap in dsDNA. C-terminal interaction with DNA ends facilitated core domain binding to DNA, whereas interaction with gaps prevented core domain–DNA complexing, implying that p53 might adopt distinct conformations upon binding to different DNA lesions. These observations suggest that both single-strand and double-strand breaks can serve as a target for p53 C-terminal recognition in vivo and indicate that p53 might recruit different repair factors to the sites of damaged DNA depending on the type of lesion. 相似文献
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The Mdm2 protein is the major regulator of the tumor suppressor protein p53. We show that the p53 protein associates both with the N-terminal and with the central domain of Mdm2. The central p53-binding site of Mdm2 encompasses amino acids 235-300. Binding of p53 to the central domain is significantly enhanced after phosphorylation of the central domain of Mdm2. The N-terminal and central domains of Mdm2 act synergistically in binding to p53. p53 mutants that have mutations in the tetramerization domain and that fail to oligomerize do not show such an enhancement of binding in the presence of the other binding site. 相似文献
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