scholarly journals Insulin-like Growth Factor-1 Regulates Endogenous RUNX2 Activity in Endothelial Cells through a Phosphatidylinositol 3-Kinase/ERK-dependent and Akt-independent Signaling Pathway

2004 ◽  
Vol 279 (41) ◽  
pp. 42709-42718 ◽  
Author(s):  
Meng Qiao ◽  
Paul Shapiro ◽  
Rakesh Kumar ◽  
Antonino Passaniti
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Signaling Pathway ◽  
Insulin Like Growth Factor ◽  
Phosphatidylinositol 3 Kinase ◽  
Phosphatidylinositol 3

scholarly journals Insulin-like growth factor induces phosphorylation of immunoreactive insulin receptor substrate and its association with phosphatidylinositol-3 kinase in human thymocytes.

1995 ◽  
Vol 182 (2) ◽  
pp. 593-597 ◽  
Author(s):  
R Kooijman ◽  
J J Lauf ◽  
A C Kappers ◽  
G T Rijkers
Keyword(s):  
T Cells ◽  
Growth Factor ◽  
Insulin Receptor ◽  
Signaling Pathway ◽  
Insulin Receptor Substrate ◽  
Type I ◽  
Insulin Like Growth Factor ◽  
Phosphatidylinositol 3 Kinase ◽  
Igf I ◽  
Phosphatidylinositol 3

Insulin receptor substrate 1 (IRS-1) is the principle cellular substrate for insulin and insulin-like growth factor I (IGF-I) receptor signaling. After phosphorylation of tyrosine residues within the YMXM or YXXM motifs, IRS-1 associates with phosphatidylinositol-3 kinase (PI3K). This signaling pathway and the presence of an IRS-1-like molecule have been demonstrated in IRS-1-transfected and in nontransfected hematopoietic cell lines, respectively. IGF-I has been implicated in lymphocyte development and function, and recently, we showed that functional type-I IGF receptors are present on human thymocytes and peripheral T cells. In this study, we addressed IGF-I signal transduction in nontransformed, freshly isolated, human thymocytes, as well as in blood T cells. Using Western blot analysis, we found that IGF-I induced phosphorylation of a 160-180-kD protein (pp170) in human thymocytes and that phosphorylated pp170 becomes associated with PI3K and is recognized by anti-IRS-1. In blood T cells, this immunoreactive IRS-1 (irIRS-1) is less abundantly expressed than in thymocytes, as assessed with immunoblotting. As a consequence, phosphorylated pp170 was not or hardly detectable after stimulation with IGF-I, and irIRS-1 was not detected in PI3K immunoprecipitates from lysates of IGF-I-stimulated T cells. However, IGF-I induced the tyrosine phosphorylation of other cellular proteins, indicating that differential expression of irIRS-1 contributes to a distinct signaling pathway in T cells.

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