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

Academic Article

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.
  • Keywords

  • Animals, Autoradiography, Blotting, Western, Colon, Cross-Linking Reagents, Humans, Immunohistochemistry, Insulin-Like Growth Factor II, Intestinal Mucosa, Mannosephosphates, Rabbits, Radioligand Assay, Rats, Receptors, Somatomedin
  • Digital Object Identifier (doi)

    Author List

  • Pillion DJ; Grizzle WE; Yang M; Meezan E; Stockard CR; Ganapathy V; Leibach FH; Myers RB; Haskell JF
  • Start Page

  • R1101
  • End Page

  • R1110
  • Volume

  • 264
  • Issue

  • 6 Pt 2