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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2019.01044

Identification of domains and factors involved in MINIYO nuclear import

  • 1Department of Molecular Genetics of Plants, National Center of Biotechnology (CSIC), Spain
  • 2Centro de Biotecnología y Genómica de Plantas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Spain
  • 3Institute of Molecular and Cellular Biology of Plants, Polytechnic University of Valencia, Spain

The transition of stem cells from self-renewal into differentiation is tightly regulated to assure proper development of the organism. Arabidopsis MINIYO (IYO) and its mammalian orthologue RNA Polymerase II Associated Protein 1 (RPAP1) are essential factors for initiating stem cell differentiation in plants and animals. Moreover, there is evidence suggesting that the translocation of IYO and RPAP1 from the cytosol into the nucleus functions as a molecular switch to initiate this cell fate transition. Identifying the determinants of IYO subcellular localization would allow testing if, indeed, nuclear IYO migration triggers cell differentiation and could provide tools to control this crucial developmental transition. Through transient and stable expression assays in Nicotiana benthamiana and Arabidopsis thaliana we demonstrate that IYO contains two nuclear localization signals (NLSs), located at the N- and C-terminus of the protein, which mediate the interaction with the NLS-receptor IMPA4 and the import of the protein into the nucleus. Interestingly, IYO also interacts with GPN GTPases, which are involved in selective nuclear import of RNA polymerase II. This interaction is prevented when the G1 motif in GPN1 is mutated, suggesting that IYO binds specifically to the nucleotide-bound form of GPN1. In contrast, deleting the NLSs in IYO does not prevent the interaction with GPN1, but it interferes with import of GPN1 into the nucleus, indicating that IYO and GPN1 are co-transported as a complex that requires the IYO NLSs for import. This work unveils key domains and factors involved in IYO nuclear import, which may prove instrumental to determine how IYO and RPAP1 control stem cell differentiation.

Keywords: stem cell, differentiation, nuclear localization signal (NLS), Importin, GTPase

Received: 22 May 2019; Accepted: 29 Jul 2019.

Copyright: © 2019 Contreras, Kalemi, González-García, Lazarova, Sánchez-Serrano, Sanmartín and Rojo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Maite Sanmartín, Institute of Molecular and Cellular Biology of Plants, Polytechnic University of Valencia, Valencia, 46022, Spain,
Dr. Enrique Rojo, Department of Molecular Genetics of Plants, National Center of Biotechnology (CSIC), Madrid, 28049, Madrid, Spain,