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Developmental patterns of insulin-like growth factor-I and -II synthesis and regulation in rat fibroblasts

Developmental patterns of insulin-like growth factor-I and -II synthesis and regulation in rat... Insulin-like growth factor-I (IGF-I) and IGF-II are chemically similar polypeptides with related receptor specificity and in vitro biological activity1. IGF-I and IGF-II have a 62% amino acid sequence identity and are 38–48% homologous with the A and B domains of human proinsulin. They can be distinguished by specific radioimmunoassays, appear to have different patterns of hormonal regulation, and presumably serve different in vivo biological functions. Plasma IGF-I levels reflect circulating concentrations of pituitary growth hormone (GH), and exogenous IGF-I substitutes for GH in inducing somatic and skeletal growth in GH-deficient rats2. Several recent observations in rats have suggested a possible role for IGF-II in fetal growth. IGF-II levels are 20- to 100-fold higher in fetal rat serum than in maternal serum and decline within days after birth3. IGF-I exhibits the reciprocal developmental pattern—low in the early neonate, rising to adult levels by approximately 4 weeks of age4,5. We recently reported6 that cultured rat embryo fibroblasts synthesize large amounts of multiplication-stimulating activity (MSA or rIGF-II), the rat homologue of human IGF-II7. We now demonstrate that fibroblast cultures established from rats 2 to 50 days of age mimic the developmental switch from IGF-II to IGF-I production observed in serum. In addition, we show that placental lactogen (PL) but not GH stimulates IGF-II synthesis in fetal fibroblasts. By contrast, both GH and PL stimulate IGF-I synthesis in fibroblasts from older rats with no effect on IGF-II synthesis. Stimulation of IGF-II synthesis in fetal fibroblasts by PL provides a mechanism whereby PL may regulate fetal growth. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Springer Journals

Developmental patterns of insulin-like growth factor-I and -II synthesis and regulation in rat fibroblasts

Adams, S. O.; Nissley, S. P.; Handwerger, S.; Rechler, M. M.
Nature , Volume 302 (5904) – Mar 10, 1983
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References (20)

Publisher
Springer Journals
Copyright
Copyright © 1983 by Nature Publishing Group
Subject
Science, Humanities and Social Sciences, multidisciplinary; Science, Humanities and Social Sciences, multidisciplinary; Science, multidisciplinary
ISSN
0028-0836
eISSN
1476-4687
DOI
10.1038/302150a0
Publisher site
See Article on Publisher Site

Abstract

Insulin-like growth factor-I (IGF-I) and IGF-II are chemically similar polypeptides with related receptor specificity and in vitro biological activity1. IGF-I and IGF-II have a 62% amino acid sequence identity and are 38–48% homologous with the A and B domains of human proinsulin. They can be distinguished by specific radioimmunoassays, appear to have different patterns of hormonal regulation, and presumably serve different in vivo biological functions. Plasma IGF-I levels reflect circulating concentrations of pituitary growth hormone (GH), and exogenous IGF-I substitutes for GH in inducing somatic and skeletal growth in GH-deficient rats2. Several recent observations in rats have suggested a possible role for IGF-II in fetal growth. IGF-II levels are 20- to 100-fold higher in fetal rat serum than in maternal serum and decline within days after birth3. IGF-I exhibits the reciprocal developmental pattern—low in the early neonate, rising to adult levels by approximately 4 weeks of age4,5. We recently reported6 that cultured rat embryo fibroblasts synthesize large amounts of multiplication-stimulating activity (MSA or rIGF-II), the rat homologue of human IGF-II7. We now demonstrate that fibroblast cultures established from rats 2 to 50 days of age mimic the developmental switch from IGF-II to IGF-I production observed in serum. In addition, we show that placental lactogen (PL) but not GH stimulates IGF-II synthesis in fetal fibroblasts. By contrast, both GH and PL stimulate IGF-I synthesis in fibroblasts from older rats with no effect on IGF-II synthesis. Stimulation of IGF-II synthesis in fetal fibroblasts by PL provides a mechanism whereby PL may regulate fetal growth.

Journal

Nature – Springer Journals

Published: Mar 10, 1983

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