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International Journal of Cell Biology
Volume 2009, Article ID 243532, 11 pages
http://dx.doi.org/10.1155/2009/243532
Research Article

The N-Terminal Domain of Y-Box Binding Protein-1 Induces Cell Cycle Arrest in G2/M Phase by Binding to Cyclin D1

Department of Molecular Sciences, The University of Tennessee Health Science Center, Memphis, TN 38163, USA

Received 1 November 2009; Accepted 31 December 2009

Academic Editor: David Bazett-Jones

Copyright © 2009 Payal Khandelwal et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Y-box binding protein YB-1 is a multifunctional protein involved in cell proliferation, regulation of transcription and translation. Our previous study indicated that disruption of one allele of Chk-YB-1b gene in DT-40 cells resulted in major defects in the cell cycle. The abnormalities seen in heterozygous mutants could be attributed to a dominant negative effect exerted by the disrupted YB-1 allele product. To test this hypothesis the N-terminal sequence of the YB-1 was fused with the third helix of antennapedia and the green fluorescent protein. These purified fusion proteins were introduced into rat hepatoma cells and their effect on cell proliferation was studied. Results indicate that the N-terminal 77 amino acid domain of the YB-1 protein induced the cells to arrest in G2/M phase of the cell cycle and undergo apoptosis. Additional deletion analysis indicated that as few as 26 amino acids of the N-terminus of YB-1 can cause these phenotypic changes. We further demonstrated that this N-terminal 77 amino acid domain of YB-1 sequesters cyclin D1 in the cytoplasm of cells at G2/M phase of cell cycle. We conclude that the N-terminal domain of YB-1 plays a major role in cell cycle progression through G2/M phase of cell cycle.