Meeting Abstract
In eukaryotes, karyopherin-alpha (KPNA) importins assist in transfer of transcription factors and other molecules into the nucleus. It has become increasingly evident that learning more about KPNAs may benefit human health as their expression is misregulated in late-stage cancers, viral diseases, and several neurological disorders. The sea urchin embryo is an excellent model for these investigations and should be promoted as a tool to learn more about roles of nuclear transport in intact organisms. BLAST searches of Lytechinus variegatus pre- and postgastrula embryonic transcriptomes revealed three KPNA sequences: KPNA1/5/6, KPNA2/7, and KPNA3/4. Using wholemount in situ hybridization, mRNA distribution was examined between fertilization and pluteus stages. LvKPNAs1/5/6 and 3/4 were both clearly present during cleavage, however varied in staining. Blastulae were ubiquitously stained and transcripts in mesenchyme blastulae were restricted to vegetal cells with lower levels throughout. In gastrulae, expression was observed in the archenteron and, by prism/pluteus stages, was restricted to the gut and oral territories. Studies in vertebrates suggest these two KPNAs may regulate assembly of the mitotic apparatus (Trieselmann et al., 2003). Also, like vertebrate KPNA1, LvKPNA1/5/6 may influence neurogenesis (Yasuhara et al., 2013). Like SpBrn1/2/4 and SpSynaptotagmin B, two genes associated with neural differentiation, LvKPNA2/7 was found in patches of ectodermal cells ultimately associated with the ciliary band. Studies in mouse embryonic stem cells (Yasuhara et al., 2013) suggest that KPNA2 maintains pluripotency in neural precursors by preventing nuclear localization of the transcription factors Brn2 and Oct6. LvKPNA2/7 may play similar roles in neural differentiation of the sea urchin. LvKPNA2/7 was also present in the archenteron/gut.
