Expression of Nup98 in the Amphibian Oocyte
Nuclear Pore Complexes (NPCs) are large macromolecular assemblies (125 Mda) embedded inside the nuclear envelope to regulate the molecular trafficking between the nucleus and the cytoplasm in interphasic cells. The NPCs are composed of roughly 30 different proteins, named nucleoporins that are present in mutliple copies within one NPC. Although the structure of NPCs have been extensively analyzed by electron microscopy, how the translocation of large molecules such as RNAs and proteins through the NPC pore occurs, and which role the nucleoporins have in this process remains unclear. Recently, several nucleoporins were proposed to have other functions than the one of structuring NPCs. One of them, Nup98, was shown to shuttle between the nucleus and the cytoplasm and, when expressed in somatic cells, to distribute within several large nuclear foci. Because of its large size, the nucleus of the amphibian oocyte can be isolated and its content spread onto a slide. The chromosomes and all other nuclear organelles are then readily observable by light microscopy with an unprecedented spatial resolution. A 6myc-Nup98 RNA was synthesized in vitro and micro-injected into the cytoplasm of stage V Xenopus oocytes. We determined, using laser scanning confocal fluorescence microscopy, that the newly made 6myc-Nup98 accumulates within Cajal bodies (CBs) in the nucleus. CBs were previously implicated in the transcription and processing of all nuclear RNAs. Thus, our data supports the recently described role of Nup98 in RNA maturation.
School:
University of Illinois at Urbana-Champaign
Department:
Cell and Developmental Biology
Research Advisor:
Michel Bellini
Department of Research Advisor:
Cell and Developmental Biology
Year of Publication:
2006