In animal embryos, primordial germ cells (PGCs) migrate long distances to the developing gonads. During this journey, programmed cell death removes abnormal, misplaced or excess cells. The regulation of this process, which ensures germline integrity, is poorly understood. Now, Clark Coffman and co-workers report that the tumour suppressor p53 and Outsiders (a monocarboxylate transporter) regulate programmed cell death during PGC development in Drosophila (see ). They show that in loss-of-function p53 and outsiders embryos, the programmed cell death (but not migration) of PGCs is abnormal, resulting in the persistence of ectopic PGCs outside of the gonads. This p53phenotype (the first developmental phenotype seen for loss of Drosophila p53 function) closely resembles that of outsiders mutants, note the researchers. Furthermore, overexpression of p53 in the PGCs of outsiders embryos partly suppresses the cell death phenotype. Thus,p53 and Outsiders may function in a common pathway to eliminate a subset of PGCs during embryogenesis.
