Spindle orientation
We study how mitotic spindles are oriented in the context of tissues, in particular in epithelial tissues, where cells divide symmetrically to give rise to two identical daughter cells.
Spindle Rotation in Drosophila epithelia
Tubulin-RFP (red) and Centrosomin-GFP (green) are used to reveal the mitotic spindle and poles. Confocal imaging of live tissue. Each frame is a merge of two planes spaced 0.5 mm apart. Frames taken 15 seconds apart. = 5 μm.
How is the spindle-orienting force positioned?
Oriented cell divisions are critical to animal development; they promote cell diversity and help to organize and expand tissues. A conserved set of proteins controls the orientation that cells divide in animals. We are working to understand how this complex functions, and why it seems to function differently depending on the tissue context.
The orientation of cell division determines the position of the daughter cells after mitosis. In many instances, division orientation drives asymmetry, meaning that the two division products take on different fates. Stem and progenitor cells direct their divisions to ensure that while one cell keeps its stem cell identity, the other cell differentiates.
Spindle orientation is also implicated in symmetrical cell division. Cells within an epithelial monolayer tend to orient their divisions such that both daughters are born within the tissue layer. In this way, oriented symmetric cell division is proposed to regulate the shape of epithelial tubes in the mammalian lung and kidney.