Persistent Link:
http://hdl.handle.net/10150/298798
Title:
Mechanisms involved in p53 regulation
Author:
Gaitonde, Supriya Vishwaraj
Issue Date:
2000
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Inactivation of the tumor suppressor protein p53 is a very important and common step in the process of carcinogenesis. The overall purpose of this project was to gain a better understanding of the mechanisms involved in the regulation of p53 function. To gain insight into these mechanisms, we chemically mutagenized A1-5 cells expressing high levels of temperature sensitive p53 val135 (tsp53) and selected for clones that were capable of growth at the permissive temperature for p53 activation. The clones generated, called ALTR (for A&barbelow;1-5 L&barbelow;ow T&barbelow;emperature R&barbelow;esistant), could grow at the permissive temperature. Using the ALTR cell system and the parent A1-5 cells, we determined that nuclear translocation of p53 could result in a change in the conformation from mutant to wild-type but that these may be two separable events. We also investigated, in depth, the mechanism by which p53 was inactivated in one ALTR cell line, ALTR 9. We identified calpain mediated degradation of p53 as a partial mechanism of p53 inactivation in these cells. Our results suggest that degradation of p53 by calpain can lead to the functional inactivation of p53 and that this degradation can be regulated by genomic stress. To gain insight into the significance of cytoplasmically sequestered p53 protein in tumors, we chose a neuroblastoma derived cell line, SK-N-SH, that expresses a wild-type but cytoplasmically sequestered p53 protein. We report here, that down regulation of p53 by HPV-16 E6 resulted in the morphological conversion of SK-N-SH cells to substrate-adherent fibroblast-like S-type cells. The morphologic conversion was accompanied by a loss of neurofilament expression, a marker for the neuronal N-type cells, an increase in the expression of vimentin, a lack of responsiveness to RA induced neuronal differentiation, and loss of anchorage independent growth. These results suggest that p53 is required for the maintenance of the neuroblastic tumorigenic phenotype. Both the ALTR cell system and the SK-N-SH cells provided us with insight into the mechanisms involved in p53 inactivation resulting in tumor formation.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Cell.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Cancer Biology
Degree Grantor:
University of Arizona
Advisor:
Martinez, Jesse D.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleMechanisms involved in p53 regulationen_US
dc.creatorGaitonde, Supriya Vishwarajen_US
dc.contributor.authorGaitonde, Supriya Vishwarajen_US
dc.date.issued2000en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractInactivation of the tumor suppressor protein p53 is a very important and common step in the process of carcinogenesis. The overall purpose of this project was to gain a better understanding of the mechanisms involved in the regulation of p53 function. To gain insight into these mechanisms, we chemically mutagenized A1-5 cells expressing high levels of temperature sensitive p53 val135 (tsp53) and selected for clones that were capable of growth at the permissive temperature for p53 activation. The clones generated, called ALTR (for A&barbelow;1-5 L&barbelow;ow T&barbelow;emperature R&barbelow;esistant), could grow at the permissive temperature. Using the ALTR cell system and the parent A1-5 cells, we determined that nuclear translocation of p53 could result in a change in the conformation from mutant to wild-type but that these may be two separable events. We also investigated, in depth, the mechanism by which p53 was inactivated in one ALTR cell line, ALTR 9. We identified calpain mediated degradation of p53 as a partial mechanism of p53 inactivation in these cells. Our results suggest that degradation of p53 by calpain can lead to the functional inactivation of p53 and that this degradation can be regulated by genomic stress. To gain insight into the significance of cytoplasmically sequestered p53 protein in tumors, we chose a neuroblastoma derived cell line, SK-N-SH, that expresses a wild-type but cytoplasmically sequestered p53 protein. We report here, that down regulation of p53 by HPV-16 E6 resulted in the morphological conversion of SK-N-SH cells to substrate-adherent fibroblast-like S-type cells. The morphologic conversion was accompanied by a loss of neurofilament expression, a marker for the neuronal N-type cells, an increase in the expression of vimentin, a lack of responsiveness to RA induced neuronal differentiation, and loss of anchorage independent growth. These results suggest that p53 is required for the maintenance of the neuroblastic tumorigenic phenotype. Both the ALTR cell system and the SK-N-SH cells provided us with insight into the mechanisms involved in p53 inactivation resulting in tumor formation.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Cell.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineCancer Biologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMartinez, Jesse D.en_US
dc.identifier.proquest3002521en_US
dc.identifier.bibrecord.b41426721en_US
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