A transcription factor of lipid synthesis, sterol regulatory element-binding protein (SREBP)-1a causes G(1) cell-cycle arrest after accumulation of cyclin-dependent kinase (cdk) inhibitors.
FEBS J
; 274(17): 4440-52, 2007 Sep.
Article
em En
| MEDLINE
| ID: mdl-17662109
ABSTRACT
Sterol regulatory element-binding protein (SREBP)-1a is a unique membrane-bound transcription factor highly expressed in actively growing cells and involved in the biosynthesis of cholesterol, fatty acids, and phospholipids. Because mammalian cells need to synthesize membrane lipids for cell replication, the functional relevance of SREBP-1a in cell proliferation has been considered a biological adaptation. However, the effect of this potent lipid-synthesis activator on cell growth has never been explored. Here, we show that induction of nuclear SREBP-1a, but not SREBP-2, completely inhibited cell growth in inducible Chinese hamster ovary (CHO) cell lines. Growth inhibition occurred through G(1) cell-cycle arrest, which is observed in various cell types with transient expression of nuclear SREBP-1a. SREBP-1a caused the accumulation of cyclin-dependent kinase (cdk) inhibitors such as p27, p21, and p16, leading to reduced cdk2 and cdk4 activities and hypophosphorylation of Rb protein. In contrast to transactivation of p21, SREBP-1a activated p27 by enhancing stabilization of the protein through inhibition of SKP2 and KPC1. In vivo, SREBP-1a-expressing livers of transgenic mice exhibited impaired regeneration after partial hepatectomy. SREBP-1-null mouse embryonic fibroblasts had a higher cell proliferation rate than wild-type cells. The unexpected cell growth-inhibitory role of SREBP-1a provides a new paradigm to link lipid synthesis and cell growth.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fase G1
/
Quinases Ciclina-Dependentes
/
Inibidores de Proteínas Quinases
/
Proteína de Ligação a Elemento Regulador de Esterol 1
/
Lipídeos
Tipo de estudo:
Etiology_studies
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article