Insulin activates the alpha isoform of class II phosphoinositide 3-kinase.
J Biol Chem
; 274(21): 14529-32, 1999 May 21.
Article
em En
| MEDLINE
| ID: mdl-10329640
ABSTRACT
The novel class II phosphoinositide (PI) 3-kinases are characterized by the presence of a C-terminal C2 domain, but little is known about their regulation. We find insulin causes a rapid 2-3-fold increase in the activity of PI 3-kinase C2alpha (PI3K-C2alpha) in CHO-IR cells, 3T3-L1 adipocytes, and fully differentiated L5L6 myotubes. No insulin-induced activation of PI3K-C2alpha was observed in cell types known to have low responsiveness to insulin including HEK 293 cells, 3T3-L1 preadipocytes, and undifferentiated L5L6 myoblasts. The mechanism of activation of PI3K-C2alpha by insulin differs from that of class Ia PI 3-kinases in that insulin stimulation did not cause PI3K-C2alpha to associate with IRS-1 or insulin receptor. PI3K-C2alpha existed as a doublet, and insulin stimulation caused a redistribution from the lower molecular weight band to the higher molecular weight band, suggesting phosphorylation-induced bandshift. Consistent with this, in vitro phosphatase treatment reduced the intensity of the upper band back to that seen in unstimulated cells. This suggests that insulin-induced phosphorylation could play a role in regulation of the activity of PI3K-C2alpha. The finding that insulin activates PI3K-C2alpha in cell types known to possess a wide range of responses to insulin suggests that PI3K-C2alpha is a novel component of insulin-stimulated signaling cascades.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfatidilinositol 3-Quinases
/
Insulina
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1999
Tipo de documento:
Article
País de afiliação:
Reino Unido