scholarly journals Parathyroid hormone increases the concentration of insulin-like growth factor-I and transforming growth factor beta 1 in rat bone.

1995 ◽  
Vol 96 (2) ◽  
pp. 767-774 ◽  
Author(s):  
J Pfeilschifter ◽  
F Laukhuf ◽  
B Müller-Beckmann ◽  
W F Blum ◽  
T Pfister ◽  
...  
1993 ◽  
Vol 290 (3) ◽  
pp. 901-905 ◽  
Author(s):  
D R Poyner ◽  
M R Hanley ◽  
T R Jackson ◽  
P T Hawkins

The activation of phosphoinositide 3-hydroxykinase (P13K) is currently believed to represent the critical regulatory event which leads to the production of a novel intracellular signal. We have examined the control of this pathway by a number of cell-surface receptors in NG115-401L-C3 neuronal cells. Insulin-like growth factor-I stimulated the accumulation of 3-phosphorylated inositol lipids in intact cells and the appearance of P13K in antiphosphotyrosine-antibody-directed immunoprecipitates prepared from lysed cells, suggesting that P13K had been activated by a mechanism involving a protein tyrosine kinase. In contrast, P13K in these cells was not regulated by a variety of G-protein-coupled receptors, nerve growth factor acting via a low affinity receptor, or receptors for transforming growth factor-beta and interleukin-1. The receptor-specificity of P13K activation in these cells places significant constraints on the possible physiological function(s) of this pathway.


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