Asymmetric stem cell division and pathology: insights from Drosophila stem cell systems.

Adult stem cells maintain many tissues and organs throughout the life of an organism by serving as renewable sources of differentiated cells. While stem cells remain in a relatively undifferentiated state, their daughters can commit to differentiation to acquire distinct cell fates. Therefore, a stem cell's choice between self-renewal and commitment to differentiation is of critical importance to the maintenance of functional tissues and organs. Many adult stem cells can divide asymmetrically to produce one self-renewed stem cell and one differentiated daughter, preserving the critical balance between stem cell and differentiated cell populations. Stem cell dysfunction and/or malfunction have been proposed to lead to several human pathologies, including tumourigenesis and tissue degeneration, yet whether a failure of asymmetric division is a primary cause of stem cell-related pathologies remains largely uninvestigated. Here, I discuss the implications of asymmetric stem cell division in pathology.