Axin determines cell fate by controlling the p53 activation threshold after DNA damage.

Cells can undergo either cell-cycle arrest or apoptosis after genotoxic stress, based on p53 activity(1-6). Here we show that cellular fate commitment depends on Axin forming distinct complexes with Pirh2, Tip60, HIPK2 and p53. In cells treated with sublethal doses of ultra-violet (UV) radiation or doxorubicin (Dox), Pirh2 abrogates Axin-induced ...
p53 phosphorylation at Ser 46 catalysed by HIPK2, by competing with HIPK2 for binding to Axin. However, on lethal treatment, Tip60 interacts with Axin and abrogates Pirh2-Axin binding, forming an Axin-Tip60-HIPK2-p53 complex that allows maximal p53 activation to trigger apoptosis. We also provide evidence that the ATM/ATR pathway mediates the Axin-Tip60 complex assembly. An axin mutation promotes carcinogenesis in Axin(Fu)/+ (Axin-Fused) mice, consistent with a dominantnegative role for Axin(Fu) in p53 activation. Thus, Axin is a critical determinant in p53-dependent tumour suppression in which Pirh2 and Tip60 have different roles in triggering cell-cycle arrest or apoptosis depending on the severity of genotoxic stress.
Mesh Terms:
Animals, Apoptosis, Cell Cycle Proteins, Cell Line, Tumor, Cell Lineage, DNA Damage, DNA-Binding Proteins, Histone Acetyltransferases, Humans, Mice, Mutation, Papilloma, Protein Binding, Protein Kinases, Protein-Serine-Threonine Kinases, Repressor Proteins, Tumor Suppressor Protein p53, Tumor Suppressor Proteins, Ubiquitin-Protein Ligases
Nat. Cell Biol.
Date: Sep. 01, 2009
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