Insulin-like growth factor binding protein-5 (IGFBP-5) is produced by osteoblasts and potentiates IGF mitogenic actions in osteoblast cultures. Progesterone (PG) increases osteoblast proliferation and increases osteoblast IGFBP-5 expression. Mechanisms underlying PG induction of IGFI3P-5 expression were investigated in U2 human osteosarcoma cells. In nuclear run-on analyses, PG increased IGF)3P-5 gene transcription to 400% of control. To define the underlying mechanisms, the human IGF13P-5 gene proximal promoter was cloned and sequenced. The proximal 500 bp of this region contains TATA and CAAT boxes, five putative PG response element (PRE) half-sites and two tandem CACCC boxes. Chloramphenicol acetyltransferase (CAT) reporter constructs containing up to 753 bp of the human IGFBP-5 gene 5'-flanking sequence were made. In U2 cells transfected with reporter construct pCAT753 containing positions -753 to t23, PG increased CAT activity to 134% of untreated control activity (P
Thomas A. Linkhart
Donna D. Strong
R. Bruce Wilcox
Aladar A. Szalay
John F. Sands
Doctor of Philosophy (PhD)
Year Degree Awarded
Date (Title Page)
Library of Congress/MESH Subject Headings
Progesterone; Insulin-Like Growth-Factor-Binding-Protein 5; Reverse Transcriptions; Osteoblasts
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This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.
Boonyaratanakornicit, Viroj, "Progesterone Regulation of Insulin like-Growth Factor : Binding Protein-5 Gene Transcription in Human Osteoblasts" (1996). Loma Linda University Electronic Theses, Dissertations & Projects. 658.
Loma Linda University Electronic Theses and Dissertations
Loma Linda University. Del E. Webb Memorial Library. University Archives