The centriolar satellite protein SSX2IP promotes centrosome maturation

• DOI: 10.1083/jcb.201302122
• Publication Date: 2013-07-02T04:37:39Z
• Authors: Felix Bärenz; Daigo Inoue; Hideki Yokoyama; Justus Tegha-Dunghu; Stephanie Freiss; Stefanie Draeger; Dmytro Mayilo; Ivana Cado; Sabine Merker; Maren Klinger; Burkhard Hoeckendorf; Sahra Pilz; Kerstin Hupfeld; Herbert Steinbeisser; Holger Lorenz; Thomas Ruppert; Joachim Wittbrodt; Oliver J. Gruss
• Keywords: Centrosome; Proteomics; 0301 basic medicine; Blastomeres; Embryo, Nonmammalian; Oryzias; Mitosis; Spindle Apparatus; Xenopus Proteins; Time-Lapse Imaging; Chromosomes; Neoplasm Proteins; Repressor Proteins; Xenopus laevis; 03 medical and health sciences; Tubulin; Chromosome Segregation; Gene Knockdown Techniques; Oocytes; Animals; Research Articles; Centrioles

Meiotic maturation in vertebrate oocytes is an excellent model system for microtubule reorganization during M-phase spindle assembly. Here, we surveyed changes in the pattern of microtubule-interacting proteins upon Xenopus laevis oocyte maturation by quantitative proteomics. We identified the synovial sarcoma X breakpoint protein (SSX2IP) as a novel spindle protein. Using X. laevis egg extracts, we show that SSX2IP accumulated at spindle poles in a Dynein-dependent manner and interacted with the γ-tubulin ring complex (γ-TuRC) and the centriolar satellite protein PCM-1. Immunodepletion of SSX2IP impeded γ-TuRC loading onto centrosomes. This led to reduced microtubule nucleation and spindle assembly failure. In rapidly dividing blastomeres of medaka (Oryzias latipes) and in somatic cells, SSX2IP knockdown caused fragmentation of pericentriolar material and chromosome segregation errors. We characterize SSX2IP as a novel centrosome maturation and maintenance factor that is expressed at the onset of vertebrate development. It preserves centrosome integrity and faithful mitosis during the rapid cleavage division of blastomeres and in somatic cells.