Phospholipase C delta 1 regulates cell proliferation and cell-cycle progression from G1- to S-phase by control of cyclin E-CDK2 activity.
Biochem J
; 415(3): 439-48, 2008 Nov 01.
Article
em En
| MEDLINE
| ID: mdl-18588506
ABSTRACT
In the present study, we examined the role of PLC delta 1 (phospholipase C delta 1) in the regulation of cellular proliferation. We demonstrate that RNAi (RNA interference)-mediated knockdown of endogenous PLC delta 1, but not PLC beta 3 or PLC epsilon, induces a proliferation defect in Rat-1 and NIH 3T3 fibroblasts. The decreased proliferation was not due to an induction of apoptosis or senescence, but was associated with an approx. 60% inhibition of [(3)H]thymidine incorporation. Analysis of the cell cycle with BrdU (bromodeoxyuridine)/propidium iodide-labelled FACS (fluorescence-activated cell sorting) demonstrated an accumulation of cells in G(0)/G(1)-phase and a corresponding decrease in cells in S-phase. Further examination of the cell cycle after synchronization by serum-starvation demonstrated normal movement through G(1)-phase but delayed entry into S-phase. Consistent with these findings, G(1) cyclin (D2 and D3) and CDK4 (cyclin-dependent kinase 4) levels and associated kinase activity were not affected. However, cyclin E-associated CDK2 activity, responsible for G(1)-to-S-phase progression, was inhibited. This decreased activity was accompanied by unchanged CDK2 protein levels and paradoxically elevated cyclin E and cyclin E-associated CDK2 levels, suggesting inhibition of the cyclin E-CDK2 complex. This inhibition was not due to altered stimulatory or inhibitory phosphorylation of CDK2. However, p27, a Cip/Kip family CKI (CDK inhibitor)-binding partner, was elevated and showed increased association with CDK2 in PLC delta 1-knockdown cells. The result of the present study demonstrate a novel and critical role for PLC delta 1 in cell-cycle progression from G(1)-to-S-phase through regulation of cyclin E-CDK2 activity and p27 levels.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fase G1
/
Fase S
/
Ciclina E
/
Proliferação de Células
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Quinase 2 Dependente de Ciclina
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Fosfolipase C delta
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Biochem J
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Estados Unidos