Investigations in Nuclear Transport
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Obando Velez, Mariana
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Abstract
The DNA, or genetic material, of eukaryotic cells serves as a set of instructions for processes within the cell and is surrounded by the nuclear membrane, a semipermeable barrier that allows small molecules to pass through unassisted while larger molecules require the help of nuclear transport proteins, such as karyopherins. There are three forms of karyopherins: exportins (which aid in the movement of molecules out of the nucleus), transportins (which move molecules both into and out of the nucleus), and importins (which are responsible for the transport of molecules into the nucleus). All karyopherin forms function to shuttle cargo (e.g. transcription factors, histones, ribosomal proteins, etc.) across the nuclear membrane by interacting with nuclear pore complexes. Once in the nucleus, these molecules can interact with DNA or participate in other nuclear functions. Because of this, it has been hypothesized that karyopherins could play a significant role in regulation of gene transcription as well as other cellular processes. Using wholemount <i>in situ</i> hybridization (WMISH) in embryos of the sea urchin <i>Lytechinus variegatus</i>, we examined the spatiotemporal expression of several karyopherins. Optimization of WMISH was performed via controlled trials utilizing the <i>L. variegatus</i> Endo16 transcript and then distributions of two karyopherins were tested: Importin 5 (IPO5) and Exportin 1 (XPO1). RNA probes for both karyopherins were successfully transcribed. Although WMISH results for IPO5 were inconsistent and no conclusive data was obtained, preliminary data was obtained for XPO1. These results suggest that XPO1 may be ubiquitously expressed at 12, 16, 18, and 22 hours postfertilization (hpf). The Byrum lab plans to perform further investigations to confirm these preliminary observations.
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Nuclear transport, sea urchins, karyopherins, importins, transportins, IPO5, XPO1