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Identification of insulin-like growth factor binding proteins in human oviduct
L C Giudice1, B A Dsupin, J C Irwin
1Department of Gynecology and Obstetrics, Stanford University Medical Center, California 94305.
Objective:
To determine if human oviduct expresses messenger ribonucleic acids (mRNAs) encoding insulin-like growth factor binding proteins (IGFBPs), if oviductal epithelium secretes IGFBPs into conditioned medium (CM), and if IGFBP secretion is regulated by steroid hormones.
Design:
Northern blots of RNA, isolated from late proliferative phase human fimbria and oviductal isthmus, were probed with complementary deoxyribonucleic acids encoding IGFBP-1, IGFBP-2, IGFBP-3, and IGFBP-4. In addition, oviductal ampullary epithelial cells were cultured with and without estrogen and/or progesterone (P), and IGFBPs were examined in CM by Western ligand blot analysis and identified using specific antisera.
Setting:
Tissue was obtained from hysterectomy specimens at Stanford University Hospital, a private teaching institution.
Patients, Participants:
Patients undergoing hysterectomy for benign disease.
Interventions:
None.
Main Outcome Measures:
Transcripts of IGFBP mRNA and IGFBPs secreted into CM were detected by autoradiography of Northern and Western ligand blots, respectively.
Results:
Messenger RNA transcripts encoding IGFBP-2, -3, and -4 were detected, whereas IGFBP-1 mRNA was barely detectable in oviductal tissue. In CM, IGFBP-2 and IGFBP-3 were detected, as was a unique 24-kd IGFBP, although IGFBP-1 was not observed. Estrogen and/or P did not regulate the secretion of these IGFBPs by cultured oviductal epithelium.
Conclusions:
Human oviduct expresses mRNAs encoding IGFBP-2, IGFBP-3, and IGFBP-4, and in vitro oviductal epithelium secretes IGFBP-2, IGFBP-3, and a unique binding protein of 24 kd, which may be the recently identified IGFBP-4.