Fanconi anemia (FA) proteins are known to play roles in the cellular response to DNA interstrand cross-linking lesions; however, several reports have suggested that FA proteins play additional roles. To elucidate novel functions of FA proteins, we used yeast two-hybrid screening to identify binding partners of the Fanconi anemia complementation group A (FANCA) protein. The candidate proteins included never-in-mitosis-gene A (NIMA)-related kinase 2 (Nek2), which functions in the maintenance of centrosome integrity. The interaction of FANCA and Nek2 was confirmed in human embryonic kidney (HEK) 293T cells. Furthermore, FANCA interacted with γ-tubulin and localized to centrosomes, most notably during the mitotic phase, confirming that FANCA is a centrosomal protein. Knockdown of FANCA increased the frequency of centrosomal abnormalities and enhanced the sensitivity of U2OS osteosarcoma cells to nocodazole, a microtubule-interfering agent. In vitro kinase assays indicated that Nek2 can phosphorylate FANCA at threonine-351 (T351), and analysis with a phospho-specific antibody confirmed that this phosphorylation occurred in response to nocodazole treatment. Furthermore, U2OS cells overexpressing the phosphorylation-defective T351A FANCA mutant showed numerical centrosomal abnormalities, aberrant mitotic arrest, and enhanced nocodazole sensitivity, implying that the Nek2-mediated T351 phosphorylation of FANCA is important for the maintenance of centrosomal integrity. Taken together, this study revealed that FANCA localizes to centrosomes and is required for the maintenance of centrosome integrity, possibly through its phosphorylation at T351 by Nek2.
Keywords: Centrosome; FANCA; Nek2; Phosphorylation; Protein interaction.
Copyright © 2013 Elsevier Ltd. All rights reserved.