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Oncogene. 2009 Nov 5;28(44):3915-25. doi: 10.1038/onc.2009.248. Epub 2009 Aug 31.

The prolyl cis/trans isomerase cyclophilin 18 interacts with the tumor suppressor p53 and modifies its functions in cell cycle regulation and apoptosis.

Author information

1
Department of Biochemistry, Leibniz-Institute for Age Research (Fritz Lipmann Institute), Jena, Germany.

Abstract

The functional diversity of the tumor suppressor protein p53 is mainly regulated by protein interactions. In this study, we describe a new interaction with the peptidyl-prolyl cis/trans isomerase cyclophilin 18 (Cyp18). The interaction reduced the sequence-specific DNA binding of p53 in vitro, whereas the inhibition of the interaction increased p53-reporter gene activity in vivo. The active site of the folding helper enzyme Cyp18 was directly involved in binding. The proline-rich region (amino acids 64-91) of p53 was most likely responsible for the observed binding because a synthetic peptide comprising amino acids 68-81 of p53 inhibited this interaction, and a p53 variant containing a proline residue at position 72 (p53(P72)) interacted with Cyp18 more effectively than the corresponding p53(R72) variant. Impairment of the Cyp18-p53 interaction induced an accumulation of cells in the G2/M phase of the cell cycle, which was more pronounced when p53(P72) was expressed compared with p53(R72) in an otherwise isogenic cellular background. Moreover, p53-dependent apoptosis was elevated in Cyp18 knockout cells, suggesting an antiapoptotic potential of Cyp18-p53 complexes. Functional in vivo data hint to a possible clinical relevance of the p53-Cyp18 interaction observed.

PMID:
19718045
DOI:
10.1038/onc.2009.248
[Indexed for MEDLINE]

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