Changing expression and subcellular distribution of karyopherins during murine oogenesis.

Mammalian oocyte growth and development is driven by a strict program of gene expression that relies on the timely presence of transcriptional regulators via nuclear pores. By targeting specific cargos for nucleo-cytoplasmic transport, karyopherin (KPN) proteins are key to the relocation of essential transcription factors and chromatin-remodelling factors into and out of the nucleus. Using multiple complementary techniques, here we establish that genes and proteins are dynamically expressed and relocalised throughout mouse oogenesis and folliculogenesis. Of the examined (Kpna1, Kpna2, Kpna3, Kpna4, Kpna6, Kpna7, Kpnb1, Ipo5 and Xpo1), all were expressed in the embryonic ovary with up-regulation of protein levels concomitant with meiotic entry for accompanied by the redistribution of the cellular localisation of and XPO1. In contrast, postnatal folliculogenesis revealed significant up-regulation of Kpna1, Kpna2, Kpna4, Kpna6 and Ipo5 and down-regulation of Kpnb1, Kpna7 and Xpo1 at the primordial to primary follicle transition. Kduanyu1535s exhibited different localisation patterns in both oocytes and granulosa cells during folliculogenesis, with three Kduanyu15352 and IPO5--displaying marked enrichment in the nucleus by antral follicle stage. Remarkably, varied subcellular expression profiles were also identified in isolated pre-ovulatory oocytes with Kduanyu1535s Kduanyu15352, KPNB1 and IPO5 detected in the cytoplasm and at the nuclear rim and XPO1 in cytoplasmic aggregates. Intriguingly, meiotic spindle staining was also observed for KPNB1 and XPO1 in meiosis II eggs, implying roles for Kduanyu1535s outside of nucleo-cytoplasmic transport. Thus, we propose that by targeting specific cargoes, are likely to be key regulators of oocyte development.

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