Characterization of insulin-like growth factor-I/somatomedin-C receptors on human keratinocyte monolayers

Pratima Misra, Brian J. Nickoloff, Vera B. Morhenn, Raymond L. Hintz, Ron G. Rosenfeld

Research output: Contribution to journalArticle

50 Scopus citations

Abstract

A membrane receptor for insulin on cultured human keratinocyte monolayers has recently been reported. It has also been established by previous investigators that the receptors for insulin and the somatomedin peptide, insulin-like growth factor-I/somatomedin-C (IGF-I), have similar oligomeric composition. However, these 2 receptors can be distinguished by their high affinitiy for their respective peptides. The present study was undertaken to identify and characterize IGF-I receptors on human keratinocytes, using time courses at different temperatures, competitive displacement of [125I]IGF-I by unlabeled IGF-I and insulin, and comparative binding of IGF-I, IGF-II, and insulin. The binding of[125I]IGF-I was time and temperature dependent, achieving steady state after 6 h of incubation at 15°C. Specific binding at 15°C averaged 4.33% for 0.8-1.0 million cells. Competition for binding was observed at IGF-I concentrations as low as 1 ng/ml, with half maximal displacement of [125I]IGF-I at IGF-I concentration of 17 ng/ml. Insulin, on the other hand, was 100-fold less potent than IGF-I in displacing [125I]IGF-I. Scatchard analysis of the competitive binding data revealed a curvilinear plot, with a calculated Kd = 1.4 × 10-9 mol/liter. When the binding of [125I]IGF-I, -IGF-II, and -insulin was compared in the same experiment, the specific binding of [125I]IGF-I was 3.43% as compared with 5.60% for [125I]insulin and 0.90% for [125I]IGF-II. The finding of specific IGF-I receptors on cultured human keratinocytes suggests a possible role for this mitogenic peptide in epidermal cell proliferation.

Original languageEnglish (US)
Pages (from-to)264-267
Number of pages4
JournalJournal of Investigative Dermatology
Volume87
Issue number2
DOIs
StatePublished - Aug 1986

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Dermatology
  • Cell Biology

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