Abstract
YES-associated protein (YAP) is a part of the Hippo pathway, with pivotal roles in several developmental processes and dual functionality as both a tumor suppressor and an oncogene. In the present study, we identified YAP activity as a microtubular scaffold protein that maintains the stability of the mitotic spindle and midbody by physically interacting with α-tubulin during mitotic progression. The interaction of YAP and α-tubulin was evident in co-immunoprecipitation assays, as well as observing their co-localization in the microtubular structure of the mitotic spindle and midbody in immunostainings. With YAP depletion, levels of ECT2, MKLP-1, and Aurora B are reduced, which is consistent with YAP functioning in midbody formation during cytokinesis. The concomitant decrease in α-tubulin and increase in acetyl-α-tubulin during YAP depletion occurred at the post-transcriptional level. This suggests that YAP maintains the stability of the mitotic spindle and midbody, which ensures appropriate chromosome segregation during mitotic division. The increase in acetyl-α-tubulin during YAP depletion may provide a lesion-halting mechanism in maintaining the microtubule structure. The depletion of YAP also results in multinuclearity and aneuploidy, which supports its role in stabilizing the mitotic spindle and midbody.