Tank-Binding Kinase 1 Associates With Centrosomes And Regulates Microtubule Dynamics And Mitosis

TANK Binding Kinase 1 (TBK1) regulates interferon signaling and NFκB function by acting as a non-canonical IκB kinase. TBK1 also participates in RalB-mediated inflammatory responses and contributes to the survival of non-small cell lung cancers (NSCLC) driven by oncogenic KRAS. In addition, TBK1 could phosphorylate and activate Akt, modulate autophagy and alter the autocrine cytokine network in cancer cells indicating oncogenic roles in addition to its immune regulatory functions. Our studies reveal that TBK1 plays a novel and direct role in promoting mitotic progression of lung cancer cells by phosphorylating multiple substrates during mitosis as well as by modulating microtubule dynamics. Levels of active phospho-TBK1 are elevated in mitotic cells where it localized to centrosomes, mitotic spindles and midbody as seen by confocal microscopy. Inhibition of TBK1 by kinase inhibitors such as BX795, Amlexanox, MRT67037 or depletion of TBK1 by shRNA resulted in mitotic defects and decreased the number of mitotic cells. TBK1 could interact with the centrosomal protein CEP170 and the nuclear mitotic apparatus protein NuMA as seen by GST binding assays, immunoprecipitation-western blot assays and proximity ligation assays. In addition, TBK1 could phosphorylate CEP170 and NuMA in in vitro kinase assays; mass spectrometry analysis revealed that TBK1 phosphorylated 12 serine residues and a threonine residue of CEP170 and five serine residues of NuMA. Inhibition or depletion of TBK1 prevented the centrosomal localization of CEP170 and the association of NuMA with the spindle poles. TBK1 depletion in A549 and H1650 cells resulted in more stable microtubules; further, depletion of TBK1 inhibited the interaction of CEP170 with the microtubule depolymerase Kif2b and the binding of NuMA to Dynein, resulting in mitotic abnormalities or mitotic arrest. In addition, inhibition of specific interaction between TBK1 and CEP170 using a 13 amino acid peptide resulted in inhibition of mitosis, enhanced microtubule stability and mitotic defects. These results are paradigm shifting that suggest TBK1 plays a significant role in regulating microtubule dynamics and mitotic progression of cells and this might have significant relevance to cancer as well as innate immune response. Citation Format: Smitha R. Pillai, Jonathan Nguyen, Joseph Johnson, Eric Haura, Domenico Coppola, Srikumar Chellappan. Tank-binding kinase 1 associates with centrosomes and regulates microtubule dynamics and mitosis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3771. doi:10.1158/1538-7445.AM2015-3771