Release of insulin-like growth factor carrier proteins by osteoblasts: Stimulation by estradiol and growth hormone

Christoph Schmid, Matthias Ernst, Jürgen Zapf, E. Rudolf Froesch

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Osteoblast-like rat calvaria cells release specific insulin-like growth factor (IGF) carrier proteins (CPs). As analyzed by SDS-PAGE under nonreducing conditions, Western blotting and detection by 125I-IGFs, CPs migrating with the IGF-binding subunits of the major CP species of rat serum (42/45/49kDa) accumulate in cell culture medium. Treatment of the cells with growth hormone and estradiol increases the abundance of this glycosylated CP species. Since the two hormones were previously found to stimulate osteoblast replication via an IGF I-dependent mechanism, the data indicate that hormones may control local IGF action not only by regulating synthesis of IGFs and their receptors but also their presentation by CPs.

Original languageEnglish
Pages (from-to)788-794
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number2
Publication statusPublished - 28 Apr 1989
Externally publishedYes

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