In fruit-fly nerve cells, the prospero gene acts as a binary switch.

In 'The Tempest', Prospero is the figure who controls the destiny of other characters. In the fruit fly Drosophila, the prospero gene is likewise a controller of fate – in this instance, of cells in the fly's nervous system.

Neural cells originate from neural stem cells, or neuroblasts. As neuroblasts repeatedly divide, some daughter cells continue to renew themselves by further division, and others start to differentiate.

In these asymmetric cell divisions, cell fate determinants – including the product of the prospero gene – are segregated into the daughter cell that then goes on to differentiate. Andrea Brand at the Wellcome Trust/Cancer Research UK Gurdon Institute and colleagues have now shown that the Prospero protein acts as a binary switch: it represses the activity of genes whose products are required for self-renewal and activates genes required for differentiation.

Prospero acts at one of the first steps in terminal differentiation, when neural stem cells produce ganglion mother cells. Notably, a ganglion mother cell lacking Prospero is transformed back into a stem cell: it divides repeatedly and expresses stem-cell-specific markers. This molecular handle on this transition could shed light on the factors controlling the fate of stem cells – in flies and potentially other organisms too.

Above image: Unlike wild-type cells, prospero mutant neural stem cells do not develop axonal projections seen in differentiated cells; courtesy of Andrea Brand.

External link

• Choksi SP et al. Prospero acts as a binary switch between self-renewal and differentiation in Drosophila neural stem cells. Dev Cell 2006;11(6):775–89.