| Summary: | 碩士 === 國立中興大學 === 生物醫學研究所 === 102 === Faithful segregation of duplicated chromosomes in mitosis requires the formation of a bipolar mitotic spindle. Loss of spindle pole integrity leads to multipolar spindle formation and abnormal chromosomal segregation. We have previously demonstrated that the actin-binding protein adducin-1 (ADD1) associates with mitotic spindles through myosin-X and is crucial for proper spindle assembly and mitotic progression. In this study, we found that the phosphorylation of ADD1 at S726 was apparently increased in mitosis and the phosphorylated ADD1 was specifically localized at mitotic centrosomes. In addition, we demonstrated that the depletion of ADD1 by short-hairpin RNA induced centriole splitting and thereby led to multiple spindle poles in mitosis, which was rescued by re-expression of FLAG tagged-ADD1 but not the S726A mutant. The depletion of protein kinase Cδ（PKCδ）prevented the phosphorylation of ADD1 at S726 and led to multipolar spindles in mitosis. Taken together, our results suggest that ADD1 may play an essential role in protecting centriole cohesion, which requires ADD1 phosphorylation at S726 by PKCδ.
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