Asymmetric cell division: recent developments and their implications for tumour biology

Abstract

Asymmetric cell division involves the segregation of cytoplasmic determinants into one of the two daughter cells. Considerable progress has been made in understanding this important biological process during the past 10 years. Cytoplasmic determinants localize asymmetrically because they are differentially modified or associate with different cytoplasmic components on the two opposing ends of a cell. Centrosomes induce the break in symmetry and initiate polarization in the one-cell Caenorhabditis elegans embryo. In Drosophila melanogaster neuroblasts, centrosomes maintain polarity over multiple cell cycles. α-subunits of heterotrimeric G proteins form complexes with microtubule-binding proteins to regulate microtubule–cell membrane attachment and position mitotic spindles. This determines the orientation of division and the size of daughter cells. Defects in asymmetric cell division can lead to tumour formation when they occur in stem cells.