Novel Interaction, Regulation of Phosphorylation and Mitotic Localization of Cell Division Cycle Associated Protein 7 (CDCA7)

Cell Division Cycle Associated Protein 7 (CDCA7) is a novel protein with poorly defined physiological significance. The proximity labeling method known as Biotin Identification (BioID) was used to determine candidate interactors of CDCA7. Mass spectrometry identified the microtubule spindle assembly protein TPX2 as a novel candidate interactor of CDCA7. Immunoprecipitation experiments verified interaction between CDCA7 and TPX2. The region of interaction was isolated to residues 195-204 of CDCA7. Based on inhibitor experiments, Aurora A kinase activity coincides with the phosphorylation of CDCA7 at the threonine (T) 163 residue. During mitosis, CDCA7 colocalizes with TPX2, localizes at centrosomes and undergoes phosphorylation at T163. These findings and previous findings in literature place CDCA7, TPX2 and potentially Aurora A kinase together within the context of mitosis. The results here demonstrate the direct interaction between CDCA7 and TPX2, and highlight residue T163 of CDCA7 as a prospective phosphorylation target of Aurora A kinase.