There and back again: amitosis to repopulate a stem cell pool

Proper maintenance of a relatively stable stem cell population is essential for many tissues, within which stem cells and their differentiated progenies function to maintain tissue homeostasis and physiological fitness, especially in response to constantly changing environmental conditions. Failure of such control is tightly linked to tissue degeneration, aging and cancer. Understanding the mechanisms by which the stem cell pool is properly maintained would shed light on the physiological causes of these diseases and facilitate the development of effective therapeutic treatments. In an article published recently in Cell Stem Cell, Lucchetta and Ohlstein investigated such mechanism in the Drosophila intestine, and found that missing stem cells can be replaced by differentiated polyploid cells through a ploidy reduction process known as amitosis (1). This exciting novel study reveals an unexpected mechanism to expand stem cell number in the intestine and respond to more favorable nutritional conditions. It is likely that the underlying principles described in this work will apply to other stem cell populations and other organisms, including in vertebrate tissues.