Characterization of PIASy, a novel regulator of the transcriptional activation function of the p53 tumor suppressor protein /
The tumor suppressor p53 is an important player in the process of tumorigenesis. The initial goal of this project was to identify novel molecular pathways involved in p53-mediated apoptosis and/or growth suppression. The experimental strategy to accomplish this goal involved application of the Mat...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=727853191&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The tumor suppressor p53 is an important player in the process of tumorigenesis. The initial goal of this project was to identify novel molecular pathways involved in p53-mediated apoptosis and/or growth suppression. The experimental strategy to accomplish this goal involved application of the Matchmaker yeast two-hybrid system to identify novel p53-protein interactions. A truncated form of murine p53 lacking the first 72 amino acids was used to screen a human brain cDNA library. The screening process yielded a number of cDNA expressing protein-binding candidates, which were cloned and sequenced. The sequence of one human clone identified it as cDNA encoding the PIASy protein. The PIASy protein is a member of the PIAS family of proteins that specifically inhibits STATs (signal transducers and activators of transcription). The binding site for PIASy was localized to within the C-terminal 100 amino acids of p53. Northern blotting showed PIASy mRNA was differentially expressed in human tissues, with highest levels being found in brain, kidney, and lung. Addition of a GFP tag to the N-terminus of PIASy (GFP-PIASy) allowed functional studies to be performed, and the GFP-PIASy protein localized predominantly to the nucleus. The GFP-PIASy fusion protein was also used to determine that PIASy promoted apoptosis and inhibited proliferation of H1299 cells. PIASy also blocked the ability of p53 to bind a consensus oligonucleotide and inhibited p53's ability to transactivate the Waf1/Cip1/p21 and bax genes. Interestingly, p53 was still capable of inducing apoptosis even though its transactivation function was compromised. The hypothesis of this dissertation is that the PIASy inhibitor is involved in the regulation of p53 during apoptosis and/or growth suppression, possibly by driving p53 into a transactivation-independent apoptotic mode of action. |
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| Item Description: | Vita. "Major Subject: Medical Sciences". |
| Physical Description: | xii, 109 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 103-108). |