V. Radha et al., Induction of p53 dependent apoptosis upon overexpression of a nuclear protein tyrosine phosphatase, FEBS LETTER, 453(3), 1999, pp. 308-312
Two ubiquitously expressed protein tyrosine phosphatases, PTP-S2 and PTP-S4
(also known as TC45 and TC48, respectively), are alternately spliced produ
cts of the same gene. Overexpression of PTP-S2 be transient transfection in
duced chromatin condensation and nuclear fragmentation, typical of apoptosi
s. Expression of PTP-S4 resulted in a much loner number of cells with apopt
otic phenotype, PTP-S2 induced apoptosis in MCF7 and A549 human tumor cell
lines which are p53 positive but not in HeLa and SW620 cells which are p53
negative. Apoptosis induced by PTP-S2 in MCF7 cells nas inhibited by cotran
sfection with mutant p53 (Arg-273 --> His) but not by wild type p53, PTP-S2
induced apoptosis was inhibited by antiapoptotic protein Bc12 and certain
inhibitors of caspases. These results suggest that the nuclear tyrosine pho
sphatase PTP-S2 induces p53 dependent, serum starvation independent and cas
pase mediated apoptosis. (C) 1999 Federation of European Biochemical Societ
ies.