Expression of IGF-II/Man-6-P receptors on rat, rabbit, and human colon epithelial cells

Am J Physiol. 1993 Jun;264(6 Pt 2):R1101-10. doi: 10.1152/ajpregu.1993.264.6.R1101.

Abstract

Previous experiments from this laboratory have established the presence of receptors for insulin and insulin-like growth factor I (IGF-I) on apical membranes prepared from rabbit colon epithelial cells; however, no receptors for multiplication-stimulating activity (MSA), the rat peptide hormone equivalent of human IGF-II, were found in this tissue. In the current studies, radioligand binding assays, covalent cross-linking experiments, and immunoblot analyses using a polyclonal rabbit antiserum that recognizes the IGF-II/mannose 6-phosphate (Man-6-P) receptor, all confirmed the presence of IGF-II/Man-6-P receptors on membranes prepared from rat and human colon epithelial cells. Exposure of rat colon epithelial cell membrane fractions to 5 mM Man-6-P before incubation with 125I-labeled IGF-II increased radioligand binding. Immunoblot analysis indicated that IGF-II/Man-6-P receptors were present in both unfractionated rat colon membranes and fractions enriched with apical membranes. Rabbit and human colon epithelial cells displayed a different pattern of receptor distribution than rat colon epithelial cells, with more insulin receptors but relatively few IGF-II/Man-6-P receptors. Immunohistochemical studies using a rabbit polyclonal antiserum confirmed that IGF-II/Man-6-P receptors were present on both the apical and the basolateral surfaces of colon epithelial cells.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Autoradiography
  • Blotting, Western
  • Colon / cytology
  • Colon / metabolism*
  • Cross-Linking Reagents
  • Humans
  • Immunohistochemistry
  • Insulin-Like Growth Factor II / metabolism*
  • Intestinal Mucosa / cytology
  • Intestinal Mucosa / metabolism*
  • Mannosephosphates / metabolism*
  • Rabbits
  • Radioligand Assay
  • Rats
  • Receptors, Somatomedin / metabolism*

Substances

  • Cross-Linking Reagents
  • Mannosephosphates
  • Receptors, Somatomedin
  • mannose-6-phosphate
  • Insulin-Like Growth Factor II