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Nat Cell Biol. 2006 Jun;8(6):586-93. Epub 2006 Apr 30.

Drosophila Pins-binding protein Mud regulates spindle-polarity coupling and centrosome organization.

Author information

1
Laboratory for Cell Asymmetry, Center for Developmental Biology, RIKEN, and CREST, Japan Science and Technology Corporation, 2-2-3 Minatojima-Minamimachi, Chuou-ku, Kobe 650-0047, Japan. izumi@cdb.riken.jp

Abstract

The orientation of the mitotic spindle relative to the cell axis determines whether polarized cells undergo symmetric or asymmetric divisions. Drosophila epithelial cells and neuroblasts provide an ideal pair of cells to study the regulatory mechanisms involved. Epithelial cells divide symmetrically, perpendicular to the apical-basal axis. In the asymmetric divisions of neuroblasts, by contrast, the spindle reorients parallel to that axis, leading to the unequal distribution of cell-fate determinants to one daughter cell. Receptor-independent G-protein signalling involving the GoLoco protein Pins is essential for spindle orientation in both cell types. Here, we identify Mushroom body defect (Mud) as a downstream effector in this pathway. Mud directly associates and colocalizes with Pins at the cell cortex overlying the spindle pole(s) in both neuroblasts and epithelial cells. The cortical Mud protein is essential for proper spindle orientation in the two different division modes. Moreover, Mud localizes to centrosomes during mitosis independently of Pins to regulate centrosomal organization. We propose that Drosophila Mud, vertebrate NuMA and Caenorhabditis elegans Lin-5 (refs 5, 6) have conserved roles in the mechanism by which G-proteins regulate the mitotic spindle.

PMID:
16648846
DOI:
10.1038/ncb1409
[Indexed for MEDLINE]

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