MOUSE INSULIN-LIKE-GROWTH-FACTOR BINDING PROTEIN-6 - EXPRESSION, PURIFICATION, CHARACTERIZATION AND HISTOCHEMICAL-LOCALIZATION

The mitogenic and metabolic activities of insulin-like growth factors (IGF) are modulated by a family of six high affinity IGF binding prote ins (IGFBPs). This study describes the expression of the mouse IGFBP-6 which is unique among IGFBPs in its preferential binding of IGF II, i n insect cells using the baculovirus system. The purified, O-glycosyla ted IGFBP-6 was functional as shown by IGF binding and by inhibition o f IGF II-stimulated DNA synthesis in human fibroblasts. Specific antib odies generated in chicken against the recombinant IGFBP-6 were used f or Western blotting analysis and immunohistochemistry. Strong immunore activity was found in ossifying bones of the cranial base, in cell clu sters of the pancreas anlage, in the trigeminal ganglion, on myoblasts , on motoneurons of the spinal cord of embryonic mice. In tissues of a dult mouse, strong IGFBP-6 immunostaining was present in epidermal and peridermal layers of the skin, in meningeal layers, in long-striated skeletal muscle, and in the Langerhans' islets of the pancreas. No imm unopositive staining was observed in lung and liver indicating that si tes of synthesis and IGFBP action are different. (C) 1998 Elsevier Sci ence Ireland Ltd. All rights reserved.