Journal of Biological Chemistry
Volume 276, Issue 34, 24 August 2001, Pages 31851-31857
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MOLECULAR BASIS OF CELL AND DEVELOPMENTAL BIOLOGY
Accelerated G1 Phase Progression Induced by the Human T Cell Leukemia Virus Type I (HTLV-I) Tax Oncoprotein*

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Tax, the human T cell leukemia virus type I oncoprotein, plays a crucial role in viral transformation and the development of the virally associated disease adult T cell leukemia. Because oncogenesis involves alterations in cell growth, it is important to examine the effects of Tax on cell cycle progression. Using a synchronized cell system, we have found that Tax expression accelerates G1 phase progression and S phase entry with concomitant DNA replication. This accelerated progression is accompanied by an earlier onset of cdk2 kinase activity. In contrast to the shortening of G1 phase, the length of S phase is unaffected by Tax expression. As a result of a more rapid cell cycle progression, cells expressing Tax exhibit faster growth kinetics and display an altered cell cycle distribution. Additionally, the decreased time allowed for growth in the presence of Tax results in a decreased cell size. Tax-associated acceleration of cell cycle progression may play a role in the ability of this viral oncoprotein to mediate cellular transformation and promote the development of human T cell leukemia virus type I-associated diseases.

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Published, JBC Papers in Press, July 7, 2001, DOI 10.1074/jbc.M105195200

*

This study was supported in part by United States Public Health Service Grant CA-77371 from NCI, National Institutes of Health (to S. J. Marriott).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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Supported in part by National Institutes of Health Training Grant CA09197.