title: Centrioles regulate centrosome size by controlling the rate of Cnn incorporation into the PCM.
abstract: BACKGROUND
  centrosomes are major microtubule organizing centers in animal cells, and they comprise a pair of centrioles surrounded by an amorphous pericentriolar material (PCM). Centrosome size is tightly regulated during the cell cycle, and it has recently been shown that the two centrosomes in certain stem cells are often asymmetric in size. There is compelling evidence that centrioles influence centrosome size, but how centrosome size is set remains mysterious.
  
  
  RESULTS
  we show that the conserved Drosophila PCM protein Cnn exhibits an unusual dynamic behavior, because Cnn molecules only incorporate into the PCM closest to the centrioles and then spread outward through the rest of the PCM. Cnn incorporation into the PCM is driven by an interaction with the conserved centriolar proteins Asl (Cep152 in humans) and DSpd-2 (Cep192 in humans). The rate of Cnn incorporation into the PCM is tightly regulated during the cell cycle, and this rate influences the amount of Cnn in the PCM, which in turn is an important determinant of overall centrosome size. Intriguingly, daughter centrioles in syncytial embryos only start to incorporate Cnn as they disengage from their mothers; this generates a centrosome size asymmetry, with mother centrioles always initially organizing more Cnn than their daughters.
  
  
  CONCLUSIONS
  centrioles can control the amount of PCM they organize by regulating the rate of Cnn incorporation into the PCM. This mechanism can explain how centrosome size is regulated during the cell cycle and also allows mother and daughter centrioles to set centrosome size independently of one another.
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
authors.forename: Paul T
authors.initials: PT
authors.lastname: Conduit
authors.forename: Kathrin
authors.initials: K
authors.lastname: Brunk
authors.forename: Jeroen
authors.initials: J
authors.lastname: Dobbelaere
authors.forename: Carly I
authors.initials: CI
authors.lastname: Dix
authors.forename: Eliana P
authors.initials: EP
authors.lastname: Lucas
authors.forename: Jordan W
authors.initials: JW
authors.lastname: Raff
mesh_terms: D000818:Animals; D002502:Centrioles / Q000378:metabolism*; D018385:Centrosome / Q000378:metabolism* / Q000648:ultrastructure*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D011993:Recombinant Fusion Proteins; C098130:cnn protein, Drosophila