Integrin-mediated adhesion orients the spindle parallel to the substratum in an EB1- and myosin X-dependent manner

• Published in: The EMBO journal Vol. 26; no. 6; pp. 1487 - 1498
• Main Authors: Toyoshima, Fumiko, Nishida, Eisuke
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 21.03.2007; Blackwell Publishing Ltd; Nature Publishing Group
• Subjects: Actins - metabolism; Adhesion; Blotting, Western; Cell adhesion & migration; Cell Adhesion - physiology; Cell culture; Cell Polarity - physiology; cell-substrate adhesion; Cellular biology; DNA Primers; EB1; HeLa Cells; Humans; integrin; Integrin beta1 - genetics; Integrin beta1 - metabolism; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - metabolism; myosin X; Myosins - metabolism; Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA, Small Interfering - genetics; Spindle Apparatus - metabolism; Spindle Apparatus - physiology; spindle orientation; Substrates
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/sj.emboj.7601599

The orientation of mitotic spindles is tightly regulated in polarized cells, but it has been unclear whether there is a mechanism regulating spindle orientation in nonpolarized cells. Here we show that integrin‐dependent cell adhesion to the substrate orients the mitotic spindle of nonpolarized cultured cells parallel to the substrate plane. The spindle is properly oriented in cells plated on fibronectin or collagen, but misoriented in cells on poly‐L‐lysine or treated with the RGD peptide or anti‐β1‐integrin antibody, indicating requirement of integrin‐mediated cell adhesion for this mechanism. Remarkably, this mechanism is independent of gravitation or cell–cell adhesion, but requires actin cytoskeleton and astral microtubules. Furthermore, myosin X and the microtubule plus‐end‐tracking protein EB1 are shown to play a role in this mechanism through remodeling of actin cytoskeleton and stabilization of astral microtubules, respectively. Our results thus uncover the existence of a mechanism that orients the spindle parallel to the cell–substrate adhesion plane, and identify crucial factors involved in this novel mechanism.