Accelerated G(1) phase progression induced by the human T cell leukemia virus type I (HTLV-I) Tax oncoprotein.
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 G(1) 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 G(1) 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.
Lemoine
F J
FJ
Interdepartmental Program of Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
Marriott
S J
SJ
D042846:CDC2-CDC28 Kinases; D002460:Cell Line; D048429:Cell Size / Q000502:physiology; D002472:Cell Transformation, Viral; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016193:G1 Phase; D016356:Gene Products, tax / Q000502:physiology*; D015368:Human T-lymphotropic virus 1 / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D016192:Resting Phase, Cell Cycle; D016196:S Phase
D016356:Gene Products, tax; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases