Repair responses to abnormalities in morphogen activity gradient

Establishing and maintaining a morphogen gradient are important in the growth and patterning of developing organs. When a discontinuity in a morphogen signal gradient is created by somatic mutant clones with aberrant intensities of morphogen signals within the Drosophila wing disc, the clones can be removed by apoptosis to restore the morphogen signal gradient. This apoptosis is termed "morphogenetic apoptosis" and has been observed to occur in a cell autonomous or non-cell autonomous manner. This review discusses possible molecular mechanisms of both autonomous and non-cell autonomous apoptosis in addition to similar cellular events in reference to recent findings.