Subcellular localization of Apak,a negative regulator of P53

Objective To study the mechanism determining the subcellular localization of Apak which negatively regulates P53.Methods Immunofluorescence assay(IF) was used to observe the subcellular localization of Apak in response to stimuli such as heat shock and DNA damage agent MMS.The localization of Apak truncated forms was analyzed under the confocal laser fluorescence microscope.Results Apak was evenly distributed in cell nuclei and gathered in nucleoli on occasion,but was accumulated mainly in the form of blob-shaped large particles in the nucleolus in response to stimuli.All the truncated forms of Apak were localized in the nucleus but presented with different ratios between the nucleolus and nucleoplasm.Conclusion Our data here demonstrate that DNA damage stimuli promote the translocation of Apak from the nucleoplasm to the nucleolus.The number of Zn-finger domains in Apak determines its nucleolus localization while the KRAB region performs a contrary function.