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In Situ Monitoring of Thermal Degradation of CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> Films by Spectroscopic Ellipsometry
摘要： High mobility group A2 (HMGA2) is an architectural transcription factor that promotes human colorectal cancer (CRC) aggressiveness by modulating the transcription of target genes. The degradation of p53 is mediated by murine double minute 2 (MDM2) in a proteasome-dependent manner. Here we report that HMGA2 promotes cell cycle progression and inhibits apoptosis in CRC cells in vitro. We also developed an intestinal epithelial cell-specific Hmga2 knock-in (KI) mouse model. It revealed that the Hmga2 KI promoted chemical carcinogen-induced tumorigenesis in the intestine in vivo. In studying the underlying molecular mechanism, we found that HMGA2 formed a protein complex with p53. The tetramerization domain of p53 (amino acids 294–393) and the three AT-hook domains (amino acids 1–83) of HMGA2 were responsible for their direct interaction. We also found that HMGA2 directly bound to MDM2 and the central acidic and zinc finger domains of MDM2 (amino acids 111–360) were required for interaction with HMGA2. Furthermore, our results indicated that HMGA2 promoted MDM2-mediated p53 ubiquitination and degradation. Interestingly, Hmga2 overexpression in Hmga2 KI mice resulted in an increase in the accumulation of ubiquitinated p53. In addition, in two large CRC cohorts, it was demonstrated that high HMGA2 expression was predictive of an adverse outcome in the p53-negative subgroup of CRC patients. In summary, our data have established for the first time a novel mechanism by which HMGA2 functions with p53 and MDM2 to promote CRC progression.
关键词： high mobility group AT-hook 2,colorectal cancer,p53
更新于2025-09-23 15:23:52
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Diarylethene moiety as an enthalpy-entropy switch: photoisomerizable stapled peptides for modulating p53/MDM2 interaction
摘要： Analogs of the known inhibitor (peptide pDI) of the p53/MDM2 protein–protein interaction are reported, which are stapled by linkers bearing a photoisomerizable diarylethene moiety. The corresponding photoisomers possess significantly different affinities to the p53-interacting domain of the human MDM2. Apparent dissociation constants are in the picomolar-to-low nanomolar range for those isomers with diarylethene in the 'open' configuration, but up to eight times larger for the corresponding 'closed' isomers. Spectroscopic, structural, and computational studies showed that the stapling linkers of the peptides contribute to their binding. Calorimetry revealed that the binding of the 'closed' isomers is mostly enthalpy-driven, whereas the 'open' photoforms bind to the protein stronger due to their increased binding entropy. The results suggest that conformational dynamics of the protein-peptide complexes may explain the differences in the thermodynamic profiles of the binding.
关键词： Photoisomerizable stapled peptides,Thermodynamic profiles,p53/MDM2 interaction,Diarylethene,Conformational dynamics
更新于2025-09-23 15:21:01
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Inverted mirror image molecular beacon-based three concatenated logic gates to detect p53 tumor suppressor gene
摘要： Mutation of p53 tumor suppressor gene represents one of the early molecular events in tumor initiation and progression. Although molecular computing holds tremendous potential with important applications in diagnosis, prognosis and treatment of human diseases at the molecular level, designing molecular logic gates to implement cascade amplification via operating autonomously for the detection of point mutations still remains challenging. In this contribution, we developed a three concatenated logic gates (TCLG) to perform multiple strand displacement amplification (m-SDA) for screening the cancer-related point mutations only via designing an innovative molecular beacon (MB). Specifically, using p53 gene as model target, extending the two ends of a MB via adding two fragments with the same sequence achieves two unique terminal single-stranded (ss) overhangs. After self-folding of MB into hairpin structure, the two overhangs exhibit a near inverted mirror image (IM) relationship if taking the base nature and direction into account. For this, the probe is called IM-MB. Because cascade SDAs can occur on IM-MB and promote each other, the target gene can be detected down to 10 pM. Along this line, the TCLG circuit was proposed, and two primers and target gene serve as the indispensable input signals. Utilizing this logic circuit, the point mutation or absence of target gene can be sensitively screened. Moreover, its potential application in the recognition of point mutations in complex biomatrix has been demonstrated via blind test. The proof-of-concept scheme is expected to provide new insight into the development of DNA-based molecular logic gates and their applications in basic research, medical diagnosis and precise treatment and treatment of genetic diseases.
关键词： Multiple strand displacement amplification,p53 tumor suppressor gene,Logic gates,DNA
更新于2025-09-23 15:21:01
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Evaluation of Light-Emitting Diodes’ Effects on the Expression Level of P53 and EGFR in the Gingival Tissues of Albino Rats
摘要： Background and objectives: The light-curing unit is considered an essential piece of equipment in every dental office. This study was conducted to evaluate the effect of Light-Emitting Diodes (LEDs) by the light cure (LC) device on gingival tissues of albino rats histologically and by regarding the expression of P53 and epidermal growth factor receptor (EGFR). Materials and methods: Gingival tissues of the rats were exposed to LEDs for 30 s with an interval of 30 s for periods of 2 and 5 min and were examined after two and four weeks of light exposure. After the set time, histological sections were studied and the P53 and EGFR expressions were evaluated immunohistochemically and by molecular methods. Results: Mild hyperplasia and mild inflammatory response were detected in higher rates after two weeks of exposure when compared to 4 weeks postexposure. Whereas fibrosis was found at a higher rate after four weeks than that found after two weeks postexposure, parakeratosis was seen only in the group that was exposed for 5 min to LC and when biopsies were taken after 2 weeks. We found that the immunohistochemical expression of P53 was not changed. Similarly, the alteration of EGFR expression was statistically nonsignificant (p > 0.05) when compared to the control group. The data obtained from the qRT-PCR reaction was analyzed using the comparative CT (2???CT) method. Statistically, there was no significant difference in the expression of EGER and P53 gene transcripts. Conclusions: LED causes no serious alteration in P53 and EGFR expression, and only trivial histopathological changes occurred, most of which recovered after a 4-week interval.
关键词： P53,qRT-PCR,EGFR,dental curing lights,blue light hazard
更新于2025-09-12 10:27:22
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Simultaneous measurement of p53:Mdm2 and p53:Mdm4 protein-protein interactions in whole cells using fluorescence labelled foci
摘要： In this report we describe the development of a fluorescent protein-protein interaction-visualization (FLUOPPI) to enable the simultaneous measurement of both Mdm2:p53 and Mdm4:p53 interactions in order to assess the relative efficiencies of mimetic molecules of the p53 peptide helix against both PPIs. Mdm2 and Mdm4 overexpression frequently leads to the inactivation of non-mutated p53 in human cancers, via inhibition of its transcriptional activity, enhancing its degradation by the proteasome or by preventing its nuclear import. Development of inhibitors to disrupt the binding of one or both of these protein interactions have been the subject of intensive pharmaceutical development for anti-cancer therapies. Using the bimodal FLUOPPI system we have characterised compounds that were either monospecific for Mdm2 or bispecific for both Mdm2 and Mdm4. We have also demonstrated that the FLUOPPI assay can reliably differentiate between specific and non-specific disruption of these protein complexes via accurate assessment and normalization to the cell population under measurement. We envision that this methodology will increase the efficiency of identifying compounds that are either specific against a single PPI from a closely related family of interactions or compounds that interact across multiple related PPI pairs, depending on which is more desirable.
关键词： Mdm4,Mdm2,protein-protein interactions,cancer therapy,FLUOPPI,p53
更新于2025-09-11 14:15:04
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Fluorescent biosensor for detection of the R248Q aggregation‐prone mutant of p53
摘要： The p53 tumour suppressor and guardian of the genome undergoes missense mutations which lead to functional inactivation in 50% human cancers. These mutations occur mostly in the DNA-binding domain of the protein and several of these result in conformational changes which lead to amyloid-like protein aggregation. Here we describe a fluorescent biosensor that reports on the R248Q mutant of p53 in vitro and in living cells, engineered through conjugation of an environmentally-sensitive probe onto a peptide derived from the primary aggregation segment of p53.This biosensor was characterized both in vitro and by fluorescence microscopy following facilitated delivery into cultured cells. We show that this biosensor preferentially reports on the p53 R248Q mutant in PC9 lung cancer cell line compared to other lung cancer cell lines harbouring either wildtype or no p53.
关键词： p53,lung cancer,fluorescent biosensor,peptide,aggregation
更新于2025-09-04 15:30:14