Insulin-Like Growth Factor-II/Mannose-6-Phosphate Receptors Are Increased in Hepatocytes from Regenerating Rat Liver*
- 1 May 1990
- journal article
- research article
- Published by The Endocrine Society in Endocrinology
- Vol. 126 (5) , 2543-2549
- https://doi.org/10.1210/endo-126-5-2543
Abstract
Insulin-like growth-factor-II (IGF-II) receptor levels were determined in hepatocytes from sham-operated and two thirds hepatectomized rats. [125I]IGF-II binding to confluent cultures increased 2-fold in cells isolated 24 and 48 h after hepatectomy compared to that in cells from sham-operated rats. Receptor levels increased from 1.74 .+-. 0.14 .times. 104/cell (sham-operated) to 3.60 .+-. 0.31 .times. 104/cell (hepatectomized; P = 0.002), with no change in affinity of IGF-II binding (Ka = 6.4 .times. 109 M-1). As previously reported, receptor levels increased in cells plated at low density, but this effect was decreased in cells from hepatectomized rats (80% increase) compared to that in cells from control rats (300% increase). Serum IGF-I levels decreased 50% 24 h after partial hepatectomy (P < 0.001), but returned to normal levels by 48 h. However, IGF-I synthesis was not decreased in hepatocytes isolated 24 h after partial hepatectomy, suggesting that decreased serum levels are due to decreased liver mass. Circulating IGF-II levels were not altered by partial hepatectomy, and IGF-II production was not detected in hepatocytes from sham-operated or hepatectomized rats. Transforming growth factor-.beta. is thought to terminate hepatocyte proliferation upon complete liver regeneration. In hepatocytes from sham-operated or hepatectomized rats transforming growth factor-.beta. totally blocked DNA synthesis, but had no effect on elevated IGF-II receptor levels after partial hepatectomy. Concomitant with increased IGF-II receptor levels, hepatocytes from hepatectomized rats were more sensitive to IGF-II stimulation of DNA synthesis. [3H]Thymidine incorporation in the presence of epidermal growth factor (50 ng/ml) was stimulated 66% by IGF-II (300 ng/ml) in control cells compared with 220% in cells from hepatectomized animals. These results suggest that IGF-II and the IGF-II receptor may play a role in liver regeneration.This publication has 25 references indexed in Scilit:
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