CELL BIOLOGY: Little and Large

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Science  24 Jan 2003:
Vol. 299, Issue 5606, pp. 475c
DOI: 10.1126/science.299.5606.475c

During neuroblast development in Drosophila, an uneven or asymmetric division occurs, producing daughter cells with different sizes that are destined for different fates. The larger apical cell carries on dividing to produce more of the smaller cells, which differentiate to form ganglion mother cells and, after one further division, two neurons or glial cells. Cai et al. studied the mechanisms involved in asymmetric division and found that mitotic spindle geometry (and thus the unequal daughter cell size) relies on two sets of signaling pathways within an apically localized protein complex. One involves Bazooka and protein kinase C, whereas the other involves Partner of Inscuteable and GMαi. Each pathway can promote asymmetric division, but if both pathways are blocked, symmetric divisions ensue. In the sensory organ precursor cells, both pathways are also active, but they cancel one another because of their localization to opposite sides of the cells. — SMH

Acknowledgments

Cell 112, 51 (2003).

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