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Specific nuclear localizing sequence directs two myosin isoforms to the cell nucleus in calmodulin-sensitive manner
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SYSNO ASEP 0387649 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Specific nuclear localizing sequence directs two myosin isoforms to the cell nucleus in calmodulin-sensitive manner Author(s) Dzijak, Rastislav (UMG-J) RID
Yildirim, Sukriye (UMG-J)
Kahle, Michal (UMG-J)
Novák, Petr (MBU-M) RID, ORCID
Hnilicová, Jarmila (UMG-J)
Venit, Tomáš (UMG-J) RID, ORCID
Hozák, Pavel (UMG-J) RID, ORCIDSource Title PLoS ONE. - : Public Library of Science - ISSN 1932-6203
Roč. 7, č. 1 (2012), e30529Number of pages 13 s. Publication form Online - E Language eng - English Country US - United States Keywords NM1 ; nuclear import ; NLS ; calmodulin Subject RIV EB - Genetics ; Molecular Biology R&D Projects GA204/07/1592 GA ČR - Czech Science Foundation (CSF) GD204/09/H084 GA ČR - Czech Science Foundation (CSF) GAP305/11/2232 GA ČR - Czech Science Foundation (CSF) LC545 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) LC06063 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) Institutional support UMG-J - RVO:68378050 ; MBU-M - RVO:61388971 CEZ AV0Z50520514 - UMG-J (2005-2011) UT WOS 000301640600037 DOI 10.1371/journal.pone.0030529 Annotation Nuclear myosin I (NM1) was the first molecular motor identified in the cell nucleus. Together with nuclear actin, they participate in crucial nuclear events such as transcription, chromatin movements, and chromatin remodeling. NM1 is an isoform of myosin 1c (Myo1c) that was identified earlier and is known to act in the cytoplasm. NM1 differs from the “cytoplasmic” myosin 1c only by additional 16 amino acids at the N-terminus of the molecule. This amino acid stretch was therefore suggested to direct NM1 into the nucleus. We investigated the mechanism of nuclear import of NM1 in detail. Using over-expressed GFP chimeras encoding for truncated NM1 mutants, we identified a specific sequence that is necessary for its import to the nucleus. This novel nuclear localization sequence is placed within calmodulin-binding motif of NM1, thus it is present also in the Myo1c. We confirmed the presence of both isoforms in the nucleus by transfection of tagged NM1 and Myo1c constructs into cultured cells, and also by showing the presence of the endogenous Myo1c in purified nuclei of cells derived from knock-out mice lacking NM1. Using pull-down and co-immunoprecipitation assays we identified importin beta, importin 5 and importin 7 as nuclear transport receptors that bind NM1. Since the NLS sequence of NM1 lies within the region that also binds calmodulin we tested the influence of calmodulin on the localization of NM1. The presence of elevated levels of calmodulin interfered with nuclear localization of tagged NM1. We have shown that the novel specific NLS brings to the cell nucleus not only the “nuclear” isoform of myosin I (NM1 protein) but also its “cytoplasmic” isoform (Myo1c protein). This opens a new field for exploring functions of this molecular motor in nuclear processes, and for exploring the signals between cytoplasm and the nucleus. Workplace Institute of Molecular Genetics Contact Nikol Škňouřilová, nikol.sknourilova@img.cas.cz, Tel.: 241 063 217 Year of Publishing 2013
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