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p53. The guardian of the genome. By Siddhartha Ray. p53: general info. 393 amino acids long Localized to the nucleus Found at locus 17p13.1 About 200 germline TP53 mutations have been discovered One of a highly conserved gene family that also includes p63 and p73
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p53 The guardian of the genome By Siddhartha Ray
p53: general info • 393 amino acids long • Localized to the nucleus • Found at locus 17p13.1 • About 200 germline TP53 mutations have been discovered • One of a highly conserved gene family that also includes p63 and p73 • However the other genes lack p53’s tumor suppressor abilities http://ghr.nlm.nih.gov/gene=tp53
Occurrence of p53 mutations in human cancers 50% Greenblatt et al. (1995) Cancer Res. 54:4855
Li-Fraumeni Syndrome (LFS) • Rare autosomal dominant predisposition to certain types of cancer • LFS has only been diagnosed in about 300 families wordwide • It has been estimated that roughly half of LFS cases involve a p53 mutation Courtesy of Dr. Bob Duronio
p53 structure • The p53 gene has 3 functional domains: • N-terminal: contains transcription activation signal • C-terminal: controls oligomerization • Central area (aa 100-300): DNA binding site, contains transcription activation signal • Most commonly mutated area in cancer is this central DNA-binding area http://www.kcl.ac.uk/kis/schools/life_sciences/life_sci/nikolovaR.html
p53 binds DNA as a tetramer, upstream of target genes Unbound p53 p53 bound to DNA http://www.rcsb.org/pdb/molecules/pdb31_1.html
There are 3 methods of activating the p53 pathway and 3 potential results Guimaraes et Hainut (2002) Biochimie 84:83
Protein interactions in the p53 pathway Guimaraes et Hainut (2002) Biochimie 84:83
p53 is involved in a mutual feedback system with its E3 ubiquitin ligase mdm2 http://www.rockefeller.edu/pubinfo/p53part2.html Courtesy of Dr. Bob Duronio
p53-mediated cell cycle arrest versus apoptosis http://www.hcoa.org/newsite/FacultyandStaff/xiangwei_wu.asp
p53 knockout mouse • p53 knockout mice were bred in 1992 by Donehower et al.
P53/mdm2 double knockout • Bred in 1995 by Jones et. al mdm2-/- p53 -/- p53-/- mdm2-/- Courtesy of Dr. Bob Duronio
3 types of mutations Guimaraes et Hainut (2002) Biochimie 84:83
Late vs early acting mutations Guimaraes et Hainut (2002) Biochimie 84:83