PtdIns(3,4,5)P3 regulates spindle orientation in adherent cells.
Cultured adherent cells divide on the substratum, leading to formation of the cell monolayer. However, how the orientation of this anchorage-dependent cell division is regulated remains unknown. We have previously shown that integrin-dependent adhesion orients the spindle parallel to the substratum, which ensures this anchorage-dependent cell division. Here, we show that phosphatidylinositol-3,4,5-triphosphate (PtdIns(3,4,5)P3) is essential for this spindle orientation control. In metaphase, PtdIns(3,4,5)P3 is accumulated in the midcortex in an integrin-dependent manner. Inhibition of phosphatidylinositol-3-OH kinase (PI(3)K) reduces the accumulation of PtdIns(3,4,5)P3 and induces spindle misorientation. Introduction of PtdIns(3,4,5)P3 to these cells restores the midcortical accumulation of PtdIns(3,4,5)P3 and proper spindle orientation. PI(3)K inhibition causes dynein-dependent spindle rotations along the z-axis, resulting in spindle misorientation. Moreover, dynactin, a dynein-binding partner, is accumulated in the midcortex in a PtdIns(3,4,5)P3-dependent manner. We propose that PtdIns(3,4,5)P3 directs dynein/dynactin-dependent pulling forces on spindles to the midcortex, and thereby orients the spindle parallel to the substratum.
Toyoshima
Fumiko
F
Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. ftoyoshima@lif.kyoto-u.ac.jp
Matsumura
Shigeru
S
Morimoto
Hiroko
H
Mitsushima
Masaru
M
Nishida
Eisuke
E
D000199:Actins / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D016764:Cell Polarity; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D000072159:Dynactin Complex; D004398:Dyneins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D016023:Integrins / Q000378:metabolism; D007672:Kidney Cortex / Q000378:metabolism; D008677:Metaphase / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D008941:Spindle Apparatus / Q000378:metabolism*; D014162:Transfection
D000199:Actins; D000072159:Dynactin Complex; D016023:Integrins; D008869:Microtubule-Associated Proteins; D018129:Phosphatidylinositol Phosphates; D034741:RNA, Small Interfering; C060974:phosphatidylinositol 3,4,5-triphosphate; D019869:Phosphatidylinositol 3-Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D004398:Dyneins