Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

cdc2 is inactivated before mitosis by phosphorylation at its inhibitory sites, Thr-14 and Tyr-15. Irradiation prevents HeLa cells from completing the G(2)-M transition, and they arrest in G(2). Whereas phosphorylation at both of these sites occurs during the G(2) arrest, the individual role of each site in the G(2) delay has not previously been investigated. We have shown that the radiation-induced G(2) delay is preserved in wild-type or cdc2-AY-transfected cells (which retain Tyr-15); this delay is abolished in cdc2-TF- or cdc2-AF-transfected cells (which lack Tyr-15). Thus Tyr-15, but not Thr-14, appears to be essential for development of a G(2) delay after radiation. Abolishment of the G(2) delay by mutation at Tyr-15 resulted in the accumulation of cells with condensed chromatin and disrupted lamin B, suggesting that these cells may be blocked at a second G(2)-M checkpoint in early mitosis (i.e., prophase). These data suggest (a) that the two inhibitory phosphorylation sites have distinct functions and that Tyr-15 phosphorylation, in particular, has a key role in the radiation-induced G(2) delay, and (b) that a second G(2)-M checkpoint exists in early mitosis and that activation of this checkpoint by radiation prevents cells that enter mitosis from progressing further.

Type

Journal article

Journal

Cancer Res

Publication Date

01/01/2002

Volume

62

Pages

241 - 250

Keywords

Binding Sites, CDC2 Protein Kinase, Chromatin, Cyclin B, Cyclin B1, G2 Phase, HeLa Cells, Humans, Lamin Type B, Lamins, Mitosis, Mutagenesis, Nuclear Proteins, Phosphorylation, Structure-Activity Relationship, Transfection, Tyrosine