Insulin-like growth factor-binding protein-3 expression and secretion by cultures of human prostate epithelial cells and stromal fibroblasts

1994 ◽  
Vol 141 (3) ◽  
pp. 535-540 ◽  
Author(s):  
R S Birnbaum ◽  
J L Ware ◽  
S R Plymate
Keyword(s):  
Growth Factor ◽  
Epithelial Cells ◽  
Conditioned Medium ◽  
Binding Protein ◽  
Human Prostate ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Cell Extracts ◽  
Prostate Epithelial Cells ◽  
Igfbp 3

Abstract Prostate-specific antigen (PSA) was recently shown to be an insulin-like growth factor-binding protein (IGFBP)-3 protease. However, only IGFBPs-2 and -4 have been identified in conditioned medium of prostate epithelial cells. Using cultures of human prostate epithelial and stromal fibroblastic cells, we examined conditioned medium and cell extracts for evidence of IGFBP-3 expression and secretion. Western ligand blotting of conditioned medium from epithelial or stromal cultures revealed the presence of IGFBPs in the molecular weight range 36–48 kDa, suggestive of IGFBP-3. Western immunoblots of these media confirmed the presence of IGFBP-3. Northern analyses of extracts of both stromal and epithelial cells showed a 2·5 kb band, the size of IGFBP-3 mRNA. We conclude that prostate cells express IGFBP-3 and that local proteolysis by PSA could modify this binding protein's actions in the prostate. Journal of Endocrinology (1994) 141, 535–540

scholarly journals Proteomic analysis identifies insulin-like growth factor-binding protein-related protein-1 as a podocyte product

2010 ◽  
Vol 299 (4) ◽  
pp. F776-F784 ◽  
Author(s):  
Takayuki Matsumoto ◽  
Sonja Hess ◽  
Hiroshi Kajiyama ◽  
Toru Sakairi ◽  
Moin A. Saleem ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epithelial Cells ◽  
Conditioned Medium ◽  
Cell Biology ◽  
Transforming Growth Factor ◽  
Binding Protein ◽  
Insulin Like Growth Factor ◽  
Related Protein ◽  
Podocyte Injury ◽  
Factor Binding

The podocyte secretory proteome may influence the phenotype of adjacent podocytes, endothelial cells, parietal epithelial cells, and tubular epithelial cells but has not been systematically characterized. We have initiated studies to characterize this proteome, with the goal of further understanding the podocyte cell biology. We cultured differentiated conditionally immortalized human podocytes and subjected the proteins in conditioned medium to mass spectrometry. At a false discovery rate of <3%, we identified 111 candidates from conditioned medium, including 44 proteins that have signal peptides or are described as secreted proteins in the UniProt database. As validation, we confirmed that one of these proteins, insulin-like growth factor-binding protein-related protein-1 (IGFBP-rP1), was expressed in mRNA and protein of cultured podocytes. In addition, transforming growth factor-β1 stimulation increased IGFBP-rP1 in conditioned medium. We analyzed IGFBP-rP1 glomerular expression in a mouse model of human immunodeficiency virus-associated nephropathy. IGFBP-rP1 was absent from podocytes of normal mice and was expressed in podocytes and pseudocrescents of transgenic mice, where it was coexpressed with desmin, a podocyte injury marker. We conclude that IGFBP-rP1 may be a product of injured podocytes. Further analysis of the podocyte secretory proteome may identify biomarkers of podocyte injury.

Production of insulin-like growth factor binding protein (IGFBP), IGFBP-3 protease, and expression of IGF-I receptors by cells of the sheep immune system

1995 ◽  
Vol 132 (1) ◽  
pp. 118-122 ◽  
Author(s):  
Elizabeth Tonner ◽  
James Beattie ◽  
David J Flint
Keyword(s):  
Immune System ◽  
Growth Factor ◽  
Conditioned Medium ◽  
Binding Protein ◽  
Lymphoid Cells ◽  
Scatchard Analysis ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Igf I ◽  
Igfbp 3

Tonner E, Beattie J, Flint DJ. Production of insulin-like growth factor binding protein (IGFBP), IGFBP-3 protease, and expression of IGF-I receptors by cells of the sheep immune system. Eur J Endocrinol 1995;132:118–22. ISSN 0804–4643 Single-cell suspensions of sheep thymus cells were cultured in serum-free medium with or without polyclonal activators (phytohaemagglutinin or concanavalin A) and the resultant conditioned medium was assayed for insulin-like growth factor binding protein (IGFBP) activity by binding of [125I]IGF-I, using charcoal to separate free from bound. All cultures produced IGFBP but mitogen stimulation significantly increased IGFBP concentrations, indicating production by lymphoid cells. Conditioned medium also degraded recombinant human [125I]IGFBP-3, suggesting IGFBP-3 protease production within the thymus. This degradation was inhibited by several protease inhibitors (phenylmethylsulphonyl fluoride, aprotinin, N-α-p-tosyl-l-lysine chloromethyl ketone), suggesting the presence of a serine protease. Cell surface [125I]IGF-I binding was demonstrated on cells from thymus, mesenteric lymph node, peripheral blood mononuclear cells and platelets. The [125I]IGF-I binding to platelets could be inhibited by unlabelled peptides, with relative potencies IGF-I > IGF-II ≫ insulin. Scatchard analysis of IGF-I competitive binding revealed a Kd of 266 pmol/l and approximately 40 receptor sites per cell. The high-affinity binding of IGF-I and competition by insulin suggested that the [125I]IGF-I binding was to an IGF-I receptor rather than to a membrane-associated IGFBP, to which insulin does not bind. These data provide further support for the role of the IGF-IGFBP axis in the immune system, particularly in relation to the thymus. Elizabeth Tonner, Hannah Research Institute, Ayr, UK

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