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Cell cycle‐dependent variations in c‐Jun and JunB phosphorylation: a role in the control of cyclin D1 expression

Cell cycle‐dependent variations in c‐Jun and JunB phosphorylation: a role in the control of... The transcription factor AP‐1, composed of Jun and Fos proteins, is a major target of mitogen‐activated signal transduction pathways. However, little is known about AP‐1 function in normal cycling cells. Here we report that the quantity and the phosphorylation state of the c‐Jun and JunB proteins vary at the M–G1 transition. Phosphorylation of JunB by the p34cdc2–cyclin B kinase is associated with lower JunB protein levels in mitotic and early G1 cells. In contrast, c‐Jun levels remain constant while the protein undergoes N‐terminal phosphorylation, increasing its transactivation potential. Since JunB represses and c‐Jun activates the cyclin D1 promoter, these modifications of AP‐1 activity during the M–G1 transition could provide an impetus for G1 progression by a temporal increase in cyclin D1 transcription. These findings constitute a novel example of a reciprocal connection between transcription factors and the cell cycle machinery. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The EMBO Journal Wiley

Cell cycle‐dependent variations in c‐Jun and JunB phosphorylation: a role in the control of cyclin D1 expression

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References (54)

Publisher
Wiley
Copyright
Copyright © 2013 Wiley Periodicals, Inc
ISSN
0261-4189
eISSN
1460-2075
DOI
10.1093/emboj/19.9.2056
pmid
10790372
Publisher site
See Article on Publisher Site

Abstract

The transcription factor AP‐1, composed of Jun and Fos proteins, is a major target of mitogen‐activated signal transduction pathways. However, little is known about AP‐1 function in normal cycling cells. Here we report that the quantity and the phosphorylation state of the c‐Jun and JunB proteins vary at the M–G1 transition. Phosphorylation of JunB by the p34cdc2–cyclin B kinase is associated with lower JunB protein levels in mitotic and early G1 cells. In contrast, c‐Jun levels remain constant while the protein undergoes N‐terminal phosphorylation, increasing its transactivation potential. Since JunB represses and c‐Jun activates the cyclin D1 promoter, these modifications of AP‐1 activity during the M–G1 transition could provide an impetus for G1 progression by a temporal increase in cyclin D1 transcription. These findings constitute a novel example of a reciprocal connection between transcription factors and the cell cycle machinery.

Journal

The EMBO JournalWiley

Published: Feb 2, 2000

Keywords: ; ; ; ;

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