Development and homeostasis depend crucially on the maintenance of cell identity, and in gamete-producing tissues the somatic/germline distinction is paramount. The conserved Drosophila tumour suppressor L(3)mbt has been implicated in maintaining somatic/germline identity: in l(3)mbt mutants, brain tumours ectopically express germline genes. However, l(3)mbt mutants also show autonomous defects in the germline, and its endogenous role during gonadogenesis has remained unclear. Now, Ruth Lehmann and colleagues characterise the function of L(3)mbt during ovarian development, and show that L(3)mbt functions through the LINT chromatin complex in a role that extends beyond maintaining somatic/germline identity. l(3)mbt mutant ovaries show numerous developmental defects, which reflect a requirement in both somatic and germ cells. While cell identities are correctly specified in l(3)mbt mutants, tissues of the developing ovary are spatially disorganised. Loss of l(3)mbt leads to expression of germline genes in somatic tissues, and the authors were able to genetically connect the somatic morphological disarrays to the misexpression of a single key regulator of the germline fate, nanos. In the female germline on the other hand, loss of l(3)mbt causes derepression of groups of genes normally expressed in testis and neuronal tissues, and this is associated with apoptotic egg chambers. This work expands our understanding of how L(3)mbt safeguards cell identity during oogenesis, uncovering more complex, tissue-specific roles than previously appreciated.

© 2018. Published by The Company of Biologists Ltd
2018