hNinein is required for targeting spindle-associated protein Astrin to the centrosome during the S and G2 phases.
Human Ninein (hNinein) is implicated in centrosomal microtubule nucleation and microtubule anchoring in interphase cells and may act as a scaffold protein, but its direct interaction partners remain unexplored in the centrosome. In this report, we show clearly that a spindle-associated protein, Astrin, interacts and co-localizes with hNinein at the centrosome during the S and G2 phases, and this complex may dissociate in the M phase. We also demonstrate that the truncated forms of hNinein, which could interfere with gamma-tubulin and function as dominant-negative mutants, are able to affect Astrin localization to the centrosome. Moreover, siRNA-mediated knockdown of hNinein in HeLa cells causes Astrin to fail to target to the centrosome, whereas hNinein can localize at the centrosome in the absence of Astrin. In addition, reduction in hNinein protein levels causes mislocalization of Astrin with the spindle apparatus and results in the formation of an aberrant mitotic spindle. Collectively, these data suggest that hNinein is required for targeting Astrin to the centrosome during the S and G2 phases. We therefore propose a model wherein hNinein regulates the dynamic movement of Astrin throughout the cell cycle and this interaction, in turn, is required for maintenance of centrosome/spindle pole integrity.
Cheng
Tai-Shan
TS
Graduate Institute of Biochemistry, Kaohsiung Medical University, Kaohsiung, Taiwan.
Hsiao
Yun-Ling
YL
Lin
Ching-Chih
CC
Hsu
Ching-Mei
CM
Chang
Mau-Sun
MS
Lee
Chu-I
CI
Yu
Ricky Chang-Tze
RC
Huang
Chi-Ying F
CY
Howng
Shen-Long
SL
Hong
Yi-Ren
YR
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D018385:Centrosome / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D016195:G2 Phase; D006801:Humans; D008954:Models, Biological; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D016196:S Phase; D008941:Spindle Apparatus / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; C512806:NIN protein, human; D009687:Nuclear Proteins; C486663:SPAG5 protein, human; D014404:Tubulin