Skip to main content
ARS Home » Northeast Area » Leetown, West Virginia » Cool and Cold Water Aquaculture Research » Research » Publications at this Location » Publication #306185
Title: Kpna7 interacts with egg-specific nuclear factors in rainbow trout (Oncorhynchus mykiss)

Author
item WANG, LEI - West Virginia University
item MA, HAO - West Virginia University
item YAO, JIANBO - West Virginia University

Submitted to: Journal of Molecular Reproduction and Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2014
Publication Date: 12/15/2014
Citation: Wang, L., Ma, H., Yao, J. 2014. Kpna7 interacts with oocyte-specific nuclear factors in rainbow trout (Oncorhynchus mykiss). Journal of Molecular Reproduction and Development. DOI: 10.1002/mrd.22433.81:1136-1145.

Interpretive Summary: To fully understand embryonic development, it is essential to identify the regulatory elements directing individual developmental processes. We identified and characterized the Kpna7 gene in rainbow trout. This gene is predominantly expressed in the ovaries and it interacts with an oocyte-specific protein, implicating it in the mediation of developmental processes that may affect egg quality.

Technical Abstract: Nuclear proteins are required for initiation of transcription in early embryos before embryonic genome activation. The regulation of transportation of nuclear proteins is mediated by transport factors known as importins (karyopherins). Kpna7 is a newly discovered member of the importin a family, which is critical for early development in mammals. In this study, we report the molecular characterization of rainbow trout Kpna7. The cDNA for rainbow trout kpna7 encodes a protein of 519 amino acids, which contains a conserved IBB (importin ß binding domain) domain and seven ARM (armadillo/beta-catenin-like repeat) motifs. RT-PCR and Western blot analyses revealed that Kpna7 is specifically expressed in mature oocytes. Real time PCR analysis demonstrated that expression of kpna7 mRNA is high in unfertilized oocytes and decreases gradually in early stage embryos until 3 day post fertilization followed by a sharp decrease reaching a level that is barely detectable in day 4 embryos and thereafter. Using a yeast two-hybrid screening system, we identified two Kpna7-interacting proteins from a rainbow trout oocyte cDNA library: Stl3 (rhamnose-binding lectin 3) and an uncharacterized protein. Both genes appear to be expressed specifically in oocytes/testis as revealed by RT-PCR analysis. Co-immunoprecipitation assays confirmed the interaction between Kpna7 and Stl3, and co-transfection experiments using EGFP-tagged Stl3 showed that Kpna7 facilitates the nuclear transportation of Stl3 through interaction with the predicted NLS cluster at the C-terminus of Stl3. Our data suggest that Kpna7 may function as a unique nuclear transport receptor for oocyte-specific proteins important for early embryonic development.