Rootletin forms centriole-associated filaments and functions in centrosome cohesion.
After duplication of the centriole pair during S phase, the centrosome functions as a single microtubule-organizing center until the onset of mitosis, when the duplicated centrosomes separate for bipolar spindle formation. The mechanisms regulating centrosome cohesion and separation during the cell cycle are not well understood. In this study, we analyze the protein rootletin as a candidate centrosome linker component. As shown by immunoelectron microscopy, endogenous rootletin forms striking fibers emanating from the proximal ends of centrioles. Moreover, rootletin interacts with C-Nap1, a protein previously implicated in centrosome cohesion. Similar to C-Nap1, rootletin is phosphorylated by Nek2 kinase and is displaced from centrosomes at the onset of mitosis. Whereas the overexpression of rootletin results in the formation of extensive fibers, small interfering RNA-mediated depletion of either rootletin or C-Nap1 causes centrosome splitting, suggesting that both proteins contribute to maintaining centrosome cohesion. The ability of rootletin to form centriole-associated fibers suggests a dynamic model for centrosome cohesion based on entangling filaments rather than continuous polymeric linkers.
Bahe
Susanne
S
Department of Cell Biology, Max-Planck-Institute for Biochemistry, D-82152 Martinsried, Germany.
Stierhof
York-Dieter
YD
Wilkinson
Christopher J
CJ
Leiss
Florian
F
Nigg
Erich A
EA
D008841:Actin Cytoskeleton / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D001324:Autoantigens / Q000378:metabolism; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D002502:Centrioles / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D018385:Centrosome / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D007399:Interphase / Q000502:physiology; D008958:Models, Molecular; D000072379:NIMA-Related Kinases; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000502:physiology; D011994:Recombinant Proteins / Q000235:genetics
D001324:Autoantigens; C499237:CROCC protein, human; D018797:Cell Cycle Proteins; C111329:CEP250 protein, human; D003598:Cytoskeletal Proteins; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; C089441:NEK2 protein, human; D000072379:NIMA-Related Kinases; D017346:Protein Serine-Threonine Kinases