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Satisfactory Essays
This research studies about the unique role of HAUSP in the p53-Mdm2 pathway. p53 is a tumor suppressor gene, so not only does it stop the formation of tumors but can also arrest growth and initiate apoptosis. Stabilization of p53 is important for these functions to occur. Now ubiquitination of proteins is useful in many cellular processes and Mdm2 mediates p53's degradation. Mdm2 is an oncoprotein that binds and blocks the N terminus of p53 repressing its activity, but interestingly p53 activates the transcription of Mdm2. HAUSP is a deubiquitylating enzyme which cleaves ubiquitin from substrate proteins. Not only does HAUSP bind and deubiquitinate p53 but it also stabilizes p53. HAUSP also stabilizes the ubiquitin ligase, Mdm2, so this study will show the dynamic role of HAUSP in the p53-Mdm2 pathway.
Constructing the p53, Mdm2, HAUSP and ubiquitin vectors meant getting expression in bacteria and mammalian cells, so cDNA sequences were amplified by PCR and subcloned into a pGEX vector and pcDNA3 vector accordingly. First, stable cell lines were made to express HAUSP short-hairpin RNA (shRNA). Then, rounds of transfection with HAUSP-specific RNA oligonucleotides were used. 24 hours before the transfection, approximately one million cells were plated on a 10 cm dish. Deubiquitination assays were carried out with different rounds of transfections.
The experiment supported that HAUSP played a positive role in the stabilization of cellular p53. Then after the rounds of transfection "severe ablation of HAUSP expression induced stabilization of p53." A different approach was used to test HAUSP ablation, but this time in another cell type. Once more endogenous HAUSP proteins were nearly not able to be detected, but th...

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...how the interaction among p53, HAUSP, and Mdm2 are dynamically regulated upon DNA damage or viral infection or is HAUSP exclusively dedicated to the p53-Mdm2 pathway?” The results section was well-written with clear subheadings. It provided evidence to support their arguments and also provided evidence to questions that might arise from their arguments. The methodology seemed appropriate but they wrote the experimental procedures after discussion. It might confuse the reader to read the results without knowing how the experiment was done, but the researchers did incorporate some methods as they stated the results in the result section. The results were supportive of previous studies as they include it in their paper.

Works Cited

Li, M., Brooks, C. L., Kon, N. and Gu, W. 2004. A Dynamic Role of HAUSP in the p53-Mdm2 Pathway. Molecular Cell, 13 pp. 879-886.
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