Epithelial polarity and spindle orientation: intersecting pathways.
During asymmetric stem cell divisions, the mitotic spindle must be correctly oriented and positioned with respect to the axis of cell polarity to ensure that cell fate determinants are appropriately segregated into only one daughter cell. By contrast, epithelial cells divide symmetrically and orient their mitotic spindles perpendicular to the main apical-basal polarity axis, so that both daughter cells remain within the epithelium. Work in the past 20 years has defined a core ternary complex consisting of Pins, Mud and Gαi that participates in spindle orientation in both asymmetric and symmetric divisions. As additional factors that interact with this complex continue to be identified, a theme has emerged: there is substantial overlap between the mechanisms that orient the spindle and those that establish and maintain apical-basal polarity in epithelial cells. In this review, we examine several factors implicated in both processes, namely Canoe, Bazooka, aPKC and Discs large, and consider the implications of this work on how the spindle is oriented during epithelial cell divisions.
The Gurdon Institute and the Department of Genetics, University of Cambridge, , Tennis Court Road, Cambridge CB2 1QN, UK.
Dan T
DT
Bergstralh
Timm
T
Haack
Daniel
D
St Johnston
D000818:Animals; D017173:Caenorhabditis elegans; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000502:physiology*; D016764:Cell Polarity / Q000502:physiology*; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism; D004847:Epithelial Cells / Q000502:physiology*; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D008941:Spindle Apparatus / Q000502:physiology*
D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D044385:GTP-Binding Protein alpha Subunits; D020730:Guanine Nucleotide Dissociation Inhibitors; D008565:Membrane Proteins; C411670:Mud protein, Drosophila; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins; C405164:Pins protein, Drosophila
epithelial polarity; mitosis; spindle orientation