Increased XXXX expression mediated through the insulin-like growth factor-I receptor in cultured fibroblasts.

@entity1 @entity754 @entity442 @entity755 @entity2856 @entity165
Plasma insulin-like growth factor-I ( @entity442 ) levels are inversely correlated with @entity755 and low density lipoprotein (LDL) @entity165 in @entity1 . To identify a molecular basis for this observation, the effects of @entity442 on @entity754 expression in fibroblasts were studied. @entity442 increased LDL receptors in cultured @entity1 skin fibroblasts at concentrations greater than 25 ng/ml. However, @entity442 effects were not easily quantitated due to secretion of inhibitory IGF-binding proteins by the cells. To circumvent this difficulty, QAYL, an @entity442 analog that binds to the @entity2856 but not to IGF-binding proteins, was used. QAYL increased @entity754 number 56-72% with half-maximum effect at 0.6 ng/ml. alpha-IR3, a monoclonal antibody directed toward the @entity2856 , blocked this effect. QAYL treatment increased synthesis of @entity754 protein without increasing @entity754 mRNA levels or altering protein stability. Both QAYL and @entity442 increased LDL receptors prominently in cells that had been treated with physiological amounts of LDL @entity165 . @entity442 , acting through the @entity2856 and modulated by IGF-binding proteins, may contribute to the regulation of LDL metabolism by increasing translation of @entity754 message.
