The STARD9/Kif16a Kinesin Associates with Mitotic Microtubules and Regulates Spindle Pole Assembly

During cell division, cells form the microtubule-based mitotic spindle, a highly specialized and dynamic structure that mediates proper chromosome transmission to daughter cells. Cancer cells can show perturbed mitotic spindles and an approach in cancer treatment has been to trigger cell killing by targeting microtubule dynamics or spindle assembly. To identify and characterize proteins necessary for spindle assembly, and potential antimitotic targets, we performed a proteomic and genetic analysis of 592 mitotic microtubule copurifying proteins (MMCPs). Screening for regulators that affect both mitosis and apoptosis, we report the identification and characterization of STARD9, a kinesin-3 family member, which localizes to centrosomes and stabilizes the pericentriolar material (PCM). STARD9-depleted cells have fragmented PCM, form multipolar spindles, activate the spindle assembly checkpoint (SAC), arrest in mitosis, and undergo apoptosis. Interestingly, STARD9-depletion synergizes with the chemotherapeutic agent taxol to increase mitotic death, demonstrating that STARD9 is a mitotic kinesin and a potential antimitotic target. [Display omitted] ► Proteomic and genetic screens identify factors contributing to cell division ► The mitotic kinesin STARD9 is required for pericentriolar matrix cohesion ► Depletion of STARD9 leads to mitotic arrest and apoptosis in multiple types of cancers ► STARD9-depletion synergizes with the chemotherapeutic agent paclitaxel Paclitaxel efficacy as an antimitotic drug is limited by toxic side effects. Loss of STARD9, a kinesin associated with daughter centrioles and the stability of pericentriolar material, synergizes with the drug to enhance apoptosis and shift Paclitaxel's effective concentration range in cells.