Ultraviolet light-induced G2 phase cell cycle checkpoint blocks cdc25-dependent progression into mitosis.
Oncogene
; 15(7): 749-58, 1997 Aug 14.
Article
in En
| MEDLINE
| ID: mdl-9266961
ABSTRACT
In response to low doses of ultraviolet (U.V.) radiation, cells undergo a G2 delay. In this study we have shown that the G2 delay results in the accumulation of inactive forms of cyclin B1/cdc2 and both the G2 and mitotic complexes of cyclin A/cdk. This appears to be through a block in the cdc25-dependent activation of these complexes. The expression and localisation of cyclin A and cyclin B1/cdk complexes are similar in U.V.-induced G2 delay and normal early G2 phase cells. Cdc25B and cdc25C also accumulate to normal G2 levels in U.V. irradiated cells, but the mitotic phosphorylation associated with increased activity of both cdc25B and cdc25C is absent. The cdc25B accumulates in the nucleus of U.V. irradiated cells and in normal G2 phase cells. Thus the block in cyclin B/cdc2 activation is in part due to the physical separation of cyclin B/cdc2, localised in the cytoplasm, from the cdc25B and cdc25C phosphatases localised in the nucleus. The data positions the U.V.-induced G2 checkpoint at either the S/G2 transition or early G2 phase, prior to the activation of cyclin A/cdk2.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
G2 Phase
/
CDC2 Protein Kinase
/
Cyclins
/
Phosphoprotein Phosphatases
/
Cell Cycle Proteins
/
Cyclin B
Limits:
Humans
Language:
En
Journal:
Oncogene
Journal subject:
BIOLOGIA MOLECULAR
/
NEOPLASIAS
Year:
1997
Document type:
Article
Affiliation country:
Australia