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Overexpressed poly(ADP‐ribose) polymerase delays the release of rat cells from p53‐mediated G 1 checkpoint
Author(s) -
WęsierskaGądek Józefa,
Schmid Gerald
Publication year - 2000
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/1097-4644(20010101)80:1<85::aid-jcb80>3.0.co;2-1
Subject(s) - poly adp ribose polymerase , cytoplasm , mutant , microbiology and biotechnology , polymerase , immunostaining , cell cycle , biology , immunoprecipitation , intracellular , cell culture , chemistry , cell , enzyme , biochemistry , immunohistochemistry , gene , genetics , immunology
We have previously reported that in cells ectopically expressing temperature‐sensitive p53 135val mutant, p53 formed tight complexes with poly(ADP‐ribose) polymerase (PARP). At elevated temperatures, p53 135val protein, adopting the mutant phenotype, was localized in the cytoplasm and sequestered the endogenous PARP. To prove whether an excess of p53 135val protein led to this unusual intracellular distribution of PARP, we have established cell lines overexpressing p53 135val + c‐Ha‐ras alone or in combination with PARP. Interestingly, immunostaining revealed that PARP is sequestered in the cytoplasm by mutant p53 in cells overexpressing both proteins. Simultaneous overexpression of PARP had no effect on temperature‐dependent cell proliferation and only negligibly affected the kinetics of p53‐mediated G 1 arrest. However, if the cells were completely growth arrested at 32°C and then shifted up to 37°C, coexpressed PARP dramatically delayed the reentry of transformed cells into the cell cycle. Even after 72 h at 37°C the proportion of S‐phase cells was reduced to 20% compared to those expressing only p53 135val + c‐Ha‐ras. The coexpressed PARP stabilized wt p53 protein and its enzymatic activity was necessary for stabilization. J. Cell. Biochem. 80:85–103, 2000. © 2000 Wiley‐Liss, Inc.