SADB phosphorylation of γ-tubulin regulates centrosome duplication

17 pages, 11 figures.-- PMID: 19648910 [PubMed].-- Printed version published Sep 2009.Supporting information available at: http://www.nature.com/ncb/journal/vaop/ncurrent/suppinfo/ncb1921_S1.htmlSymmetrical cell division requires duplication of DNA and protein content to generate two daughter cells. Centrosomes also duplicate during cell division, but the mechanism controlling this process is incompletely understood. We describe an alternative splice form of SadB encoding a short SADB Ser/Thr kinase whose activity fluctuates during the cell cycle, localizes to centrosomes, and controls centrosome duplication. Reduction of endogenous SADB levels diminished centrosome numbers, whereas enhanced SADB expression induced centrosome amplification. SADB exerted this action through phosphorylation of γ-tubulin on Ser 131, as expression of a phosphomimetic Ser 131-to-Asp γ-tubulin mutant alone increased centrosome numbers, whereas non-phosphorylatable Ala 131-γ-tubulin impaired centrosome duplication. We propose that SADB kinase activity controls centrosome homeostasis by regulating phosphorylation of γ-tubulin.This work was supported by the Spanish Ministry of Science and Innovation (SAF200405955, 200763624 to ACC, CSD 2006‑00023 to JMV), the Spanish Association against Cancer, the Spanish Ministry of Health (PI050964), the Royal Physiographic Society in Lund, the Ake Wibergs, Thelma Zoegas, OE och Edla Johanssons and U‑MAS Cancer Research Found, and fellowships from Teggers Fond, EMBO and the Swedish Society for Medical Research.Peer reviewe