Regulation of Kinetochore Recruitment of Two Essential Mitotic Spindle Checkpoint Proteins by Mps1 Phosphorylation

• DOI: 10.1091/mbc.e08-03-0324
• Publication Date: 2008-10-16T03:54:21Z
• Authors: Quanbin Xu; Songcheng Zhu; Wei Wang; Xiaojuan Zhang; William Old; Natalie Ahn; Xuedong Liu
• Keywords: 0301 basic medicine; Recombinant Fusion Proteins; Calcium-Binding Proteins; Molecular Sequence Data; Cell Cycle Proteins; Spindle Apparatus; Protein Serine-Threonine Kinases; Protein-Tyrosine Kinases; Cell Line; Repressor Proteins; 03 medical and health sciences; Mad2 Proteins; Animals; Humans; Amino Acid Sequence; Phosphorylation; RNA, Small Interfering; Kinetochores; Signal Transduction

Mps1 is a protein kinase that plays essential roles in spindle checkpoint signaling. Unattached kinetochores or lack of tension triggers recruitment of several key spindle checkpoint proteins to the kinetochore, which delays anaphase onset until proper attachment or tension is reestablished. Mps1 acts upstream in the spindle checkpoint signaling cascade, and kinetochore targeting of Mps1 is required for subsequent recruitment of Mad1 and Mad2 to the kinetochore. The mechanisms that govern recruitment of Mps1 or other checkpoint proteins to the kinetochore upon spindle checkpoint activation are incompletely understood. Here, we demonstrate that phosphorylation of Mps1 at T12 and S15 is required for Mps1 recruitment to the kinetochore. Mps1 kinetochore recruitment requires its kinase activity and autophosphorylation at T12 and S15. Mutation of T12 and S15 severely impairs its kinetochore association and markedly reduces recruitment of Mad2 to the kinetochore. Our studies underscore the importance of Mps1 autophosphorylation in kinetochore targeting and spindle checkpoint signaling.