DepartmentGermline Development
Publication date16-Apr-2019

Kazuko Hanyu-Nakamura, Kazuki Matsuda, Stephen M. Cohen and Akira Nakamura

Pgc suppresses the zygotically acting RNA decay pathway to protect germ plasm RNAs in the Drosophila embryo.

Development 146(7), 2019 doi: 10.1242/dev.167056

Specification of germ cells is pivotal to ensure continuation of animal species. In many animal embryos, germ cell specification depends on maternally supplied determinants in the germ plasm. Drosophila polar granule component (pgc) mRNA is a component of the germ plasm. pgc encodes a small protein that is transiently expressed in newly formed pole cells, the germline progenitors, where it globally represses mRNA transcription. pgc is also required for pole cell survival, but the mechanism linking transcriptional repression to pole cell survival remains elusive. We report that pole cells lacking pgc show premature loss of germ plasm mRNAs, including the germ cell survival factor, nanos, and undergo apoptosis. We found that pgcpole cells misexpress multiple miRNA genes. Reduction of miRNA pathway activity in pgcembryos partially suppressed germ plasm mRNA degradation and pole cell death, suggesting that Pgc represses zygotic miRNA transcription in pole cells to protect germ plasm mRNAs. Interestingly, germ plasm mRNAs are protected from miRNA-mediated degradation in vertebrates, albeit by a different mechanism. Thus, independently evolved mechanisms are used to silence miRNAs during germ cell specification.


Figure Schematic model for the role of Pgc-mediated transcriptional repression in primordial germ cell development.

Drosophila germ cell development is achieved through Pgc-mediated transcriptional repression and Nanos-mediated translational repression. Pgc ensures proper primordial germ cell development by repressing transcription of multiple miRNA genes and preventing degradation of germ plasm mRNAs.