Presence of insulinlike growth factor receptors and lack of insulin receptors on fetal bovine smooth muscle cells

Phillip D.K. Lee, Raymond L. Hintz, Ron G. Rosenfeld, William E. Benitz

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Previous investigations have demonstrated specific receptors and associated mitogenic actions for insulin and insulinlike growth factors I and II (IGF-I and II) in postnatal bovine aortic smooth muscle. Using fetal tissue we have observed different patterns of binding and action for these peptides. Smooth muscle cells isolated from near-term fetal bovine aortae were studied in early passage. Specific receptors for both IGF-I and IGF-II were identified. Specific binding averaged 5.7%/2.5×105 cells for IGF-I, and 16.2% for IGF-II, and 0.3% for insulin. High affinity K d for both IGF receptors were nanomolar. IGF-II was fivefold less potent than IGF-I in displacing IGF-I binding. IGF-I showed no affinity for the IGF-II receptor. Insulin, at physiologic concentrations, was incapable of displacing either IGF-I or IGF-II binding. Cellular incorporation of [methyl-3H]thymidine was stimulated at the lowest dose of IGF-I tested, 0.5 ng/ml. IGF-II showed no effect up to 100 ng/ml, after which a sharp increase in incorporation was noted. Insulin had a similar effect only at concentrations >0.5 μg/ml, with a maximal response noted at 5 to 10 μg/ml. Our results indicate that fetal bovine aortic smooth muscle cells have an abundance of IGF receptors but lack specific insulin receptors. In addition, IGF-II binding levels are three times higher than for IGF-I. These results are consistent with observations in other species, in which a predominance of IGF over insulin receptors has been demonstrated in fetal tissue, and provide further evidence for a role for the IGFs in embryonic cellular metabolism.

Original languageEnglish (US)
Pages (from-to)921-926
Number of pages6
JournalIn Vitro Cellular & Developmental Biology
Volume24
Issue number9
DOIs
StatePublished - Sep 1 1988
Externally publishedYes

Keywords

  • growth factor receptors
  • insulin
  • insulinlike growth factors
  • receptors
  • smooth muscle cells

ASJC Scopus subject areas

  • Developmental Biology
  • Clinical Biochemistry
  • Cell Biology

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