FBXL2 is a ubiquitin E3 ligase subunit that triggers mitotic arrest.

Mitotic progression is regulated by ubiquitin E3 ligase complexes to carefully orchestrate eukaryotic cell division. Here, we show that a relatively new E3 ligase component belonging to the SCF (Skip-Cullin1-F-box protein) E3 ligase family, SCF (FBXL2) , impairs cell proliferation by mediating cyclin D3 polyubiquitination and degradation. Both cyclin D3 and FBXL2 colocalize within the centrosome. FBXL2 overexpression led to G 2/M-phase arrest in transformed epithelia, resulting in the appearance of supernumerary centrosomes, tetraploidy and nuclei where condensed chromosomes are arranged on circular monopolar spindles typical of mitotic arrest. RNAi-mediated knockdown of cyclin D3 recapitulated effects of SCF (FBXL2) expression. SCF (FBXL2) impaired the ability of cyclin D3 to associate with centrosomal assembly proteins [Aurora A, polo-like kinase 4 (Plk4), CDK11]. Thus, these results suggest a role for SCF (FBXL2) in regulating the fidelity of cellular division.