In mammals, three Aurora kinases have been identified and characterized: Aurora-A, Aurora-B, and Aurora-C .
Experimental evidence showed that EWS-Fli1 protein upregulates Aurora-A and Aurora-B expression by binding to regulatory ETS-binding sites located at -84 and -71 bp upstream of the transcription initiation sites in both Aurora-A and Aurora-B promoters .
Aurora-B. The Aurora-B is encoded by the AURKB gene (also known as AIK2; AIM1; ARK2; AurB; IPL1; STK5; AIM1; STK12), mapped to chromosome 17p13.1, and consisting of 9 exons (Gene ID: 9212).
As for the Aurora-A promoter, also the Aurora-B promoter possesses the CDE and CHR elements, though responsible for the cell cycle regulation of its expression, and several CDE-binding proteins have been identified by means of electrophoretic mobility shift assay and biotinstreptavidin pull-down assay, including the E2F-1, E2F-4, and DP-2 .
As described for Aurora-A, also the Aurora-B protein is characterized by a catalytic domain, a C-terminal D-box, and an N-terminal A-box/DAD [18-21].
However, differently from Aurora-A and Aurora-B, Aurora-C does not contain the KEN and the A-box/DAD motifs in its N-terminal region, while the C-terminal D-box is present.
Aurora-B. Aurora-B mRNA and protein levels peak at G2/M phase, and the maximum kinase activity is reached from metaphase to the end of mitosis [18, 19].
Aurora-B activation requires its autophosphorylation and binding to INCENP, while all CPC components are necessary for its proper localization during mitosis.
Aurora-C is highly similar to Aurora-B in sequence (61% identity), which may explain why the two kinases display similar localization patterns and share interacting proteins and substrates such as INCENP, survivin, and borealin [18, 39].
It has been reported that the overexpression of either Aurora-A, Aurora-B, or Aurora-C induces cell malignant transformation [46-48].
The expression of Aurora-A and Aurora-B in this cell type is mainly regulated at the transcriptional level, while that of Aurora-C appears to be modulated at the posttranscriptional level .
Dang et al., "Human Aurora-B binds to a proteasome a-subunit HC8 and undergoes degradation in a proteasome-dependent manner," Molecular and Cellular Biochemistry, vol.