Functional characterization of AIBp, a novel Aurora-A binding protein in centrosome structure and spindle formation
- Authors: Ann-Shung Lieu, Tai-Shan Cheng, Chia-Hua Chou, Chia-Hung Wu, Chia-Yi Hsu, Chi-Ying F. Huang, Li-Kwan Chang, Joon-Khim Loh, Chung-Shing Chang, Ching-Mei Hsu, Shen-Long Howng, Yi-Ren Hong
Published on: 01 August 2010
- Pages: 429-436
- DOI: 10.3892/ijo_00000691
Aurora-A is involved in chromosome alignment, centrosome maturation, mitotic spindle assembly and regards to an oncogene. Aurora-A is also known to bind to several other proteins affecting its up-regulation or down-regulation and localization. However, how these different binding signals work together to regulate Aurora-A is not properly known. To explore more Aurora-A interacting proteins, the low-copy yeast two-hybrid screening using Aurora-A as bait protein was performed. One novel gene, AIBp, was demonstrated to associate with Aurora-A by the yeast two-hybrid method and in vitro GST pull-down assay. Molecular characterization showed that AIBp possessed a binding site at the C-terminal with Aurora-A (kinase domain). Interestingly, AIBp also interacts with hNinein at the N-terminal, which overlaps with a previously reported hNinein and GSK3β binding site. Using a kinase assay, AIBp interacts with the Aurora-A kinase domain functions as a positive regulator, whereas AIBp binding to hNinein appears to block the phosphorylation of hNinein by both Aurora-A and GSK3β. siRNA-mediated elimination of AIBp from HeLa cells, results in a doughnut-like shape, asymmetrical spindle pole and multiple spindle pole formation. We also demonstrated that both AIBp and Aurora-A are co-overexpressed in various brain tumors. These studies demonstrate that AIBp may not only be required for the dynamic movement of Aurora-A at the centrosomes and spindle apparatus during the cell cycle, but may also be important during brain tumorigenesis.