Similar distribution of insulin-like growth factor binding proteins-1, -2, -3 in human fetal tissues.
The actions of insulin-like growth factors (IGFs) are modulated by several specific binding proteins (IGF BPs). Since the anatomical distribution of IGF BPs is likely to dictate IGF bioavailability we used immunocytochemistry to localize IGF BP-1, -2, and -3 in early second trimester human fetal tissues. Primary antisera were directed against hIGF BP-1, bIGF BP-2 and hIGF BP-3 respectively, and showed less than 5% cross-reaction with heterologous IGF BP species. The distribution of immunopositive staining was similar for each IGF BP in many tissues being prominent in the epithelial lining of the gut, kidney and lung; in epidermis, adrenal cortex and pancreatic endocrine tissue; and in association with membranes of skeletal muscle fibres and cardiocytes. Unlike IGF BP-1 -2, IGF BP-3 was barely detectable in liver and absent from epiphyseal chondrocytes. Conversely, IGF BP-3 alone was visualized within neurons of the cerebral cortex. The co-distribution of IGF BPs in many human fetal tissues suggests that they may co-ordinately regulate IGF bioavailability in target tissues and modify IGF: receptor interactions.
Hill
D J
DJ
MRC Group in Fetal and Neonatal Health and Development, Lawson Research Institute, University of Western Ontario, St. Joseph's Health Centre, London, Canada.
Clemmons
D R
DR
D015153:Blotting, Western; D002352:Carrier Proteins / Q000032:analysis*; D005260:Female; D005333:Fetus / Q000378:metabolism*; D005865:Gestational Age; D006801:Humans; D007150:Immunohistochemistry; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018969:Insulin-Like Growth Factor Binding Proteins; D008099:Liver / Q000166:cytology / Q000378:metabolism; D009928:Organ Specificity; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D013002:Somatomedins / Q000378:metabolism
D002352:Carrier Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins