Characterizing Nuclear Pore Proteins as Multifunctional Regulators of Germline Development in Drosophila Melanogaster

Abstract

The germline develops as a functionally distinct population of cells, uniquely tasked with transmitting genetic information across generations. In Drosophila melanogaster, the identity of germ cell precursors – termed pole cells – is established by maternally deposited determinants. A maternal germ plasm containing germ granules – ribonucleoprotein assemblies that guide germline development – accumulates at the posterior, where it associates with syncytial nuclei to induce their cellularization into individual pole cells. In early stages of embryogenesis, all nuclei are transcriptionally quiescent, with maternal factors independently driving development. Pole cells retain this transcriptional quiescence for longer relative to somatic cells, a feature believed to insulate them from somatic induction, thereby safeguarding their fate. While several factors with roles in the regulation of transcription in the germline have been characterized, the full repertoire of responsible molecules remains unknown. According to the demonstrated role of nucleoporins (Nups) – proteins of the nuclear pore complex (NPC) – in gene regulation, this project explored their role in the regulation of transcriptional quiescence in the Drosophila germline. An exploration of phenotypic outcomes resulting from the RNAi-based depletion of individual Nups allowed for the characterization of four Nups as potential regulators of transcriptional quiescence in pole cells. Additionally, the investigation of unexpected phenotypes – namely infertility and defective embryonic development – allowed for the implication of several Nups in a variety of developmental processes, ranging from oogenesis to germ granule localization. These results expand our understanding of the role of the NPC beyond nucleocytoplasmic transport, potentially implicating Nups and nuclear architecture in the regulation of various stages of development across the animal kingdom.