Effects of IGFBP-2 overexpression in vitro and in vivo.

Insulin-like growth factor-binding proteins (IGFBPs) are important modulators of IGF actions and may have both stimulatory and inhibitory effects. Expression of IGFBP-2 is increased after fasting and in a variety of pathological conditions. However, the specific role of IGFBP-2 in growth physiology remains to be determined. In this review, we summarize data from in vitro and in vivo models suggesting that IGFBP-2 has mainly inhibitory effects on IGF actions. Since the growth hormone (GH)/IGF system is involved in a number of pathological alterations of the kidney and these changes may--at least in part--be due to increased IGF-I, local overexpression of inhibitory IGFBP-2 in the kidney might prevent IGF-I-induced lesions. This hypothesis will be tested by crossing GH transgenic mice, a common model of glomerulosclerosis, with transgenic mice characterized by systemic and renal overexpression of IGFBP-2.