The end of a monolith: Deconstructing the Cnn-Polo interaction

  title={The end of a monolith: Deconstructing the Cnn-Polo interaction},
  author={Robert Eisman and Melissa Phelps and Thomas C. Kaufman},
  pages={60 - 72}
ABSTRACT In Drosophila melanogaster a functional pericentriolar matrix (PCM) at mitotic centrosomes requires Centrosomin-Long Form (Cnn-LF) proteins. Moreover, tissue culture cells have shown that the centrosomal localization of both Cnn-LF and Polo kinase are co-dependent, suggesting a direct interaction. Our recent study found Cnn potentially binds to and is phosphorylated by Polo kinase at 2 residues encoded by Exon1A, the initiating exon of a subset of Cnn isoforms. These interactions are… 
The Centrioles, Centrosomes, Basal Bodies, and Cilia of Drosophila melanogaster
The structure and functions of the centriole, the centrosome, and the basal body in different tissues and cultured cells of Drosophila melanogaster are reviewed, highlighting their contributions to different aspects of development and cell division.


An Amino-Terminal Polo Kinase Interaction Motif Acts in the Regulation of Centrosome Formation and Reveals a Novel Function for centrosomin (cnn) in Drosophila
A Cnn and PoloKinase interaction is apparently required during embryogenesis and involves the exon 1A-initiating coding exon, suggesting a subset of Cnn splice variants is regulated by Polo kinase.
The centrosome is a dynamic structure that ejects PCM flares
Observations indicate that centrosomes eject particles of Cnn-containing pericentriolar material that move on dynamic astral microtubules at a rate that varies with the cell cycle, and propose that flare particles play a role in organizing the actin cytoskeleton during syncytial cleavage.
Centrosomin: A Complex Mix of Long and Short Isoforms Is Required for Centrosome Function During Early Development in Drosophila melanogaster
This study addresses several questions surrounding Cnn function at the centrosome during embryogenesis and shows that cnn function cannot be ascribed to a single protein.
Sas-4 provides a scaffold for cytoplasmic complexes and tethers them in a centrosome
The Sas-4 protein is shown to be important in mediating the formation of cytoplasmic PCM complexes and the incorporation of this material into centrosomes.
A Genome-Wide RNAi Screen to Dissect Centriole Duplication and Centrosome Maturation in Drosophila
A microscopy-based genome-wide RNA interference screen in Drosophila cells to identify proteins required for centriole duplication and mitotic PCM recruitment finds that the individual depletion of only two proteins, Polo and Centrosomin (Cnn) can completely block centrosome maturation.
Sequestration of Polo kinase to microtubules by phosphopriming-independent binding to Map205 is relieved by phosphorylation at a CDK site in mitosis.
It is proposed that Map205-dependent targeting of Polo to microtubules provides a stable reservoir of Polo that can be rapidly mobilized by the activity of Cdk1 at mitotic entry.
The Plk1-dependent Phosphoproteome of the Early Mitotic Spindle*
This study identified 358 unique Plk1-dependent phosphorylation sites on spindle proteins, including novel substrates, illustrating the complexity of the Plk2-dependent signaling network and the functional interaction between PlK1 and Aurora A on the early mitotic spindle.
The centrosomin protein is required for centrosome assembly and function during cleavage in Drosophila.
Results suggest that Centrosomin is required for the assembly and function of centrosomes during the syncytial cleavage divisions, and suggests that the primary cause of division defects in mutant embryos is centrosomal malfunction.