Aurora-A Interacts with AP-2α and Down Regulates Its Transcription Activity

Aurora-A is a serine/threonine protein kinase and plays an important role in the control of mitotic progression. Dysregulated expression of Aurora-A impairs centrosome separation and maturation, which lead to disrupted cell cycle progression and tumorigenesis. However, the molecular mechanism by which Aurora-A causes cell malignant transformation remains to be further defined. In this report, using transcription factors array and mRNA expression profiling array, we found that overexpression of Aurora-A suppressed transcription activity of AP-2 alpha, a tumor suppressor that is often downregulated in variety of tumors, and inhibited expression of AP-2 alpha-regulated downstream genes. These array-based observations were further confirmed by microwell colorimetric TF assay and luciferase reporter assay. Downregulated transcription activity of AP-2 alpha by Aurora-A was found to be associated with reduced AP-2 alpha protein stability, which appeared to be mediated by Aurora-A enhanced ubiquitin-dependent proteasomal degradation of AP-2 alpha protein. Interestingly, Aurora-A-mediated AP-2 alpha degradation was likely dependent Aurora-A kinase activity since inhibition of Aurora-A kinase activity was able to rescue Aurora-A-induced degradation of AP-2 alpha. Moreover, we defined a physical interaction between Aurora-A and AP-2 alpha, and such interaction might bridge the suppressive effect of Aurora-A on AP-2 alpha protein stability. These findings provide new insights into molecular mechanism by which Aurora-A acts as an oncogenic molecule in tumor occurrence and malignant development.