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dc.contributor.advisorDr. Steven R. Grossman
dc.contributor.authorShi, Dingding
dc.date2022-08-11T08:08:42.000
dc.date.accessioned2022-08-23T16:04:57Z
dc.date.available2022-08-23T16:04:57Z
dc.date.issued2010-01-08
dc.date.submitted2010-03-31
dc.identifier.doi10.13028/hfsb-j486
dc.identifier.urihttp://hdl.handle.net/20.500.14038/31782
dc.description.abstractp53, known as the “guardian of the genome”, is the most well-characterized tumor suppressor gene. The central role of p53 is to prevent genome instability. p53 is the central node in an incredibly elaborate genome defense network for receiving various input stress signals and controlling diverse cellular responses. The final output of this network is determined not only by the p53 protein itself, but also by other p53 cooperating proteins. p300 and CBP (CREB-Binding Protein) act as multifunctional regulators of p53 via acetylase and ubiquitin ligase activities. Prior work in vitro has shown that the N-terminal 595 aa of p300 encode both generic ubiquitin ligase (E3) and p53-directed E4 functions. Analysis of p300 or CBP-deficient cells revealed that both coactivators were required for endogenous p53 polyubiquitination and the normally rapid turnover of p53 in unstressed cells. Unexpectedly, p300/CBP ubiquitin ligase activities were absent in nuclear extracts and exclusively cytoplasmic. In the nucleus, CBP and p300 exhibited differential regulation of p53 gene target expression, C-terminal acetylation, and biologic response after DNA damage. p300 activated, and CBP repressed, PUMA expression, correlating with activating acetylation of p53 C-terminal lysines by p300, and a repressive acetylation of p53 lysine-320 induced by CBP. Consistent with their gene expression effects, CBP deficiency augmented, and p300 deficiency blocked, apoptosis after doxorubicin treatment. Subcellular compartmentalization of p300/CBP’s ubiquitination and transcription activities reconciles seemingly opposed functions—cytoplasmic p300/CBP E4 activities ubiquitinate and destabilize p53, while nuclear p300/CBP direct p53 acetylation, target gene activation, and biological outcome after genotoxic stress. p53 is a prominent tumor suppressor gene and it is mutated in more than 50% of human tumors. Reactivation of endogenous p53 is one therapeutic avenue to stop cancer cell growth. In this thesis, we have identified S5as a critical regulator of p53 degradation and activity. S5a is a non-ATPase subunit in the 19S regulatory particle of the 26S proteasome. Our preliminary data indicates that S5a is required for p53 instability and is a negative regulator of p53 tranactivation. As a negative regulator of p53, S5a may therefore also represent a new target for cancer drug development against tumors that specifically maintain wild type p53.
dc.language.isoen_US
dc.rightsCopyright is held by the author, with all rights reserved.
dc.subjectGenes
dc.subjectp53
dc.subjectTumor Suppressor Protein p53
dc.subjectp300-CBP Transcription Factors
dc.subjectCREB-Binding Protein
dc.subjectE1A-Associated p300 Protein
dc.subjectProteasome Endopeptidase Complex
dc.subjectDNA Damage
dc.subjectUbiquitination
dc.subjectAmino Acids, Peptides, and Proteins
dc.subjectCancer Biology
dc.subjectGenetic Phenomena
dc.subjectNeoplasms
dc.subjectPharmaceutical Preparations
dc.subjectTherapeutics
dc.titleDefining the Roles of p300/CBP (CREB Binding Protein) and S5a in p53 Polyubiquitination, Degradation and DNA Damage Responses: A Dissertation
dc.typeDoctoral Dissertation
dc.identifier.legacyfulltexthttps://escholarship.umassmed.edu/cgi/viewcontent.cgi?article=1454&context=gsbs_diss&unstamped=1
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/gsbs_diss/452
dc.legacy.embargo2011-02-23T00:00:00-08:00
dc.identifier.contextkey1255655
refterms.dateFOA2022-08-24T03:48:35Z
html.description.abstract<p>p53, known as the “guardian of the genome”, is the most well-characterized tumor suppressor gene. The central role of p53 is to prevent genome instability. p53 is the central node in an incredibly elaborate genome defense network for receiving various input stress signals and controlling diverse cellular responses. The final output of this network is determined not only by the p53 protein itself, but also by other p53 cooperating proteins.</p> <p>p300 and CBP (CREB-Binding Protein) act as multifunctional regulators of p53 via acetylase and ubiquitin ligase activities. Prior work in vitro has shown that the N-terminal 595 aa of p300 encode both generic ubiquitin ligase (E3) and p53-directed E4 functions. Analysis of p300 or CBP-deficient cells revealed that both coactivators were required for endogenous p53 polyubiquitination and the normally rapid turnover of p53 in unstressed cells. Unexpectedly, p300/CBP ubiquitin ligase activities were absent in nuclear extracts and exclusively cytoplasmic. In the nucleus, CBP and p300 exhibited differential regulation of p53 gene target expression, C-terminal acetylation, and biologic response after DNA damage. p300 activated, and CBP repressed, PUMA expression, correlating with activating acetylation of p53 C-terminal lysines by p300, and a repressive acetylation of p53 lysine-320 induced by CBP. Consistent with their gene expression effects, CBP deficiency augmented, and p300 deficiency blocked, apoptosis after doxorubicin treatment. Subcellular compartmentalization of p300/CBP’s ubiquitination and transcription activities reconciles seemingly opposed functions—cytoplasmic p300/CBP E4 activities ubiquitinate and destabilize p53, while nuclear p300/CBP direct p53 acetylation, target gene activation, and biological outcome after genotoxic stress.</p> <p>p53 is a prominent tumor suppressor gene and it is mutated in more than 50% of human tumors. Reactivation of endogenous p53 is one therapeutic avenue to stop cancer cell growth. In this thesis, we have identified S5as a critical regulator of p53 degradation and activity. S5a is a non-ATPase subunit in the 19S regulatory particle of the 26S proteasome. Our preliminary data indicates that S5a is required for p53 instability and is a negative regulator of p53 tranactivation. As a negative regulator of p53, S5a may therefore also represent a new target for cancer drug development against tumors that specifically maintain wild type p53.</p>
dc.identifier.submissionpathgsbs_diss/452
dc.contributor.departmentMedicine
dc.contributor.departmentProgram in Cancer Biology
dc.description.thesisprogramCancer Biology


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