Canine tracheal epithelial cells express the type 1 insulin-like growth factor receptor and proliferate in response to insulin-like growth factor I.
Disaggregated airway epithelial cells replicate in serum-free media containing supraphysiologic concentrations of insulin. To examine the hypothesis that the type 1 insulin-like growth factor (IGF) receptor mediates the mitogenic action of insulin on these cells, we studied the mitogenic effects of IGF-I and insulin, and the expression of type 1 IGF receptors in primary cultures of adult canine tracheal epithelial cells. Isolated tracheal epithelial cells were grown in varying concentrations of IGF-I or insulin in Ham's F12 medium supplemented with transferrin, cholera toxin, and endothelial cell growth supplement. Both IGF-I and insulin increased DNA synthesis (measured as [3H]thymidine incorporation into DNA) and cell number in a concentration-dependent fashion, but IGF-I was at least 20 to 60 times more potent than insulin in its mitogenic effects. No additive or synergistic effect was observed with the simultaneous addition of IGF-I and insulin in maximally effective doses. A monoclonal antibody directed against the type 1 IGF receptor (alpha IR3) blocked the mitogenic activity of both IGF-I and insulin. Affinity labeling of type 1 IGF receptors by covalent cross-linking with disuccinimidyl suberate demonstrated the tracheal epithelial cell IGF-I binding moiety to have a relative molecular weight of 130,000 D. Binding of [125I]IGF-I to this protein was inhibited by low concentrations of IGF-I, relative to insulin, and by alpha IR3. An 11-kb transcript characteristic of mRNA for the type 1 IGF receptor was recognized in poly(A+) RNA derived from cultured canine tracheal epithelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Retsch-Bogart
G Z
GZ
Department of Pediatrics, University of North Carolina, Chapel Hill 27599-7220.
Stiles
A D
AD
Moats-Staats
B M
BM
Van Scott
M R
MR
Boucher
R C
RC
D'Ercole
A J
AJ
D000818:Animals; D002455:Cell Division; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004261:DNA Replication; D004285:Dogs; D004848:Epithelium / Q000378:metabolism / Q000648:ultrastructure; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008934:Mitogens / Q000096:biosynthesis* / Q000235:genetics; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000494:pharmacology*; D014132:Trachea / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*
D008934:Mitogens; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D004247:DNA