Feo, the Drosophila Homolog of PRC1, Is Required for Central-Spindle Formation and Cytokinesis

• Published in: Current biology 2004-09, Vol.14 (17), p.1569-1575
• Main Authors: Vernı̀, Fiammetta, Somma, Maria Patrizia, Gunsalus, Kristin C., Bonaccorsi, Silvia, Belloni, Giorgio, Goldberg, Michael L., Gatti, Maurizio
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Blotting, Western; Cell Cycle Proteins - genetics; Cell Cycle Proteins - physiology; Chromosome Mapping; Cytokinesis - genetics; Cytokinesis - physiology; DNA Primers; Drosophila; Drosophila - genetics; Drosophila - physiology; Drosophila Proteins - genetics; Drosophila Proteins - physiology; Female; Gene Components; Gene Expression; Immunohistochemistry; Male; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - physiology; Molecular Sequence Data; Mutation - genetics; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Sequence Analysis, DNA; Sequence Homology; Sex Factors; Spermatocytes - metabolism; Spindle Apparatus - genetics; Spindle Apparatus - physiology; Transgenes - genetics
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2004.08.054

We performed a functional analysis of fascetto (feo), a Drosophila gene that encodes a protein homologous to the Ase1p/PRC1/MAP65 conserved family of microtubule-associated proteins (MAPs) [1–5]. These MAPs are enriched at the spindle midzone in yeast and mammals and at the fragmoplast in plants, and are essential for the organization and function of these microtubule arrays [1–5]. Here we show that the Feo protein is specifically enriched at the central-spindle midzone and that its depletion either by mutation or by RNAi results in aberrant central spindles. In Feo-depleted cells, late anaphases showed normal overlap of the antiparallel MTs at the cell equator, but telophases displayed thin MT bundles of uniform width instead of robust hourglass-shaped central spindles. These thin central spindles exhibited diffuse localizations of both the Pav and Asp proteins, suggesting that these spindles comprise improperly oriented MTs. Feo-depleted cells also displayed defects in the contractile apparatus that correlated with those in the central spindle; late anaphase cells formed regular contractile structures, but these structures did not constrict during telophase, leading to failures in cytokinesis. The phenotype of Feo-depleted telophases suggests that Feo interacts with the plus ends of central spindle MTs so as to maintain their precise interdigitation during anaphase-telophase MT elongation and antiparallel sliding.