Circulating Insulin-Like Growth Factor Binding Proteins (IGFBPs) 1 and 2 Induced in Vitamin C-Deficient or Fasted Guinea Pigs Inhibit IGF-I Action in Cultured Cells

1994 ◽  
Vol 10 (4) ◽  
pp. 229-241 ◽  
Author(s):  
Beverly Peterkofsky ◽  
Anna Gosiewska ◽  
Deborah E. Kipp ◽  
Varsha Shah ◽  
Shirley Wilson
Keyword(s):  
Growth Factor ◽  
Vitamin C ◽  
Guinea Pigs ◽  
Binding Proteins ◽  
Cultured Cells ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Igf I

Colocalization of insulin-like growth factor-binding protein with insulin-like growth factor I

1991 ◽  
Vol 261 (1) ◽  
pp. F22-F28 ◽  
Author(s):  
S. Kobayashi ◽  
D. R. Clemmons ◽  
M. A. Venkatachalam
Keyword(s):  
Growth Factor ◽  
Cultured Cells ◽  
Binding Protein ◽  
Insulin Like Growth Factor ◽  
Intense Staining ◽  
Factor Binding ◽  
Factor I ◽  
Collecting Ducts ◽  
Igf I ◽  
Growth Factor I

We report the localization of insulin-like growth factor I (IGF-I) and a 25-kDa form of insulin-like growth factor-binding protein (IGF-BP-1) in adult rat kidney. The antigens were localized using a rabbit anti-human IGF-I antibody, and a rabbit anti-human IGF-BP-1 antibody raised against human 25-kDa IGF-BP-1 purified from amniotic fluid. Immunohistochemistry by the avidin-biotin peroxidase conjugate technique showed that both peptides are located in the same nephron segments, in the same cell types. The most intense staining was in papillary collecting ducts. There was moderate staining also in cortical collecting ducts and medullary thick ascending limbs of Henle's loop. In collecting ducts the antigens were shown to be present in principal cells but not in intercalated cells. In distal convoluted tubules, cortical thick ascending limbs, and in structures presumptively identified as thin limbs of Henle's loops there was only modest staining. The macula densa, however, lacked immunoreactivity. Colocalization of IGF-I and IGF-BP-1 in the same cells supports the notion, derived from studies on cultured cells, that the actions of IGF-I may be modified by IGF-BPs that are present in the same location.

Comparison of the effectiveness of various procedures for reducing or eliminating insulin-like growth factor-binding protein interference with insulin-like growth factor-I radioimmunoassays on porcine sera

1994 ◽  
Vol 140 (2) ◽  
pp. 229-237 ◽  
Author(s):  
R S Frey ◽  
M R Hathaway ◽  
W R Dayton
Keyword(s):  
Molecular Weight ◽  
Growth Factor ◽  
Binding Proteins ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I ◽  
Igfbp 3 ◽  
Glycyl Glycine

Abstract We have examined the efficacy of various methods for reducing the interference of insulin-like growth factor-binding proteins (IGFBPs) with insulin-like growth factor-I (IGF-I) radioimmunoassays (RIAs) run on porcine sera. Acid–ethanol (AE) extraction, AE extraction followed by cryoprecipitation, glycyl–glycine (GG) extraction, GG extraction followed by Sephadex G-50 chromatography in 1 mol acetic acid/l (GG/G-50), and Sep-Pak chromatography were analysed. To provide a range of IGF-I and IGFBP levels, sera obtained from control, hypophysectomized, diabetic and somatotrophin-treated pigs were used. Recoveries of IGF-I added to sera prior to treatments other than Sep-Pak chromatography ranged from 85 to 105% and were not significantly different. In contrast, Sep-Pak chromatography gave extremely variable recoveries. 125I-Labelled IGF-I ligand blotting showed that GG extraction followed by acid G-50 chromatography was by far the most effective method of removing or inactivating IGFBPs in porcine sera. Consequently, this procedure was used as a standard against which to compare other extraction procedures. GG extraction alone removed or inactivated low molecular weight binding proteins but appeared to have little effect on IGFBP-3. AE extraction reduced the level of IGFBP-3 but had little effect on lower molecular weight binding proteins. Even though none of the tested procedures completely removed or inactivated the binding proteins, all samples yielded IGF-I displacement curves that were parallel to that obtained for IGF-I standard. Despite yielding parallel displacement curves, sera extracted by various methods gave dramatically different apparent IGF-I levels when subjected to IGF-I RIA. IGF-I RIA of GG extracted sera yielded IGF-I values that were closest to those obtained for identical serum samples subjected to glycyl-glycine extraction followed by G-50 chromatography. For sera from control, hypophysectomized, diabetic and somatotrophin-treated pigs, the relationship of the IGF-I level in GG-extracted sera to that in GG-extracted, acid G-50 chromatographed (GG/G-50) sera was √GG=1·13√GG/G-50−0·23 (r2=0·98). Consequently, GG extraction can be used to remove IGFBP interference with IGF-I RIAs of porcine sera from normal, hypophysectomized, diabetic and somatotrophin-treated animals. Journal of Endocrinology (1994) 140, 229–237

Responses of insulin-like growth factor binding protein-1 (IGFBP-1) and the IGFBP-3 complex to administration of insulin-like growth factor-I

1993 ◽  
Vol 128 (2) ◽  
pp. 101-108 ◽  
Author(s):  
Robert C Baxter ◽  
Naomi Hizuka ◽  
Kazue Takano ◽  
Sara R Holman ◽  
Kumiko Asakawa
Keyword(s):  
Single Dose ◽  
Growth Factor ◽  
Food Intake ◽  
Binding Proteins ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Factor I ◽  
Igf I ◽  
Highly Correlated ◽  
Igfbp 3

The importance of insulin-like growth factor binding proteins (IGFBPs) in modulating the bioactivity of administered IGFs is poorly understood. This study examines responses of IGFBP-1 and the IGFBP-3 complex to recombinant human IGF-I. Eight fasted subjects received a single dose of 0.1-0.125 mg/kg IGF-I sc. This caused a 10-fold rise in IGFBP-1 over 6 h. falling rapidly after food intake. Peak (6-h) IGFBP-1 values were highly correlated with peak post-prandial (8-h) glucose values (r = 0.941). IGFBP--3 showed little response, decreasing slightly over the 48-h period following IGF-I. Adaptive changes in IGFBPs were studied in fed adults injected daily for 7 days with IGF-I, 0.1 mg/kg sc. Following the first injection. IGFBP-1 had a markedly blunted response compared to that in fasted subjects. However, after the seventh IGF-I injection, a 3.5-fold greater IGFBP-1 response to the same IGF-I dose was seen. Concomitantly with the increased IGFBP-1 responsiveness, mean immunoreactive IGFBP-3 and acidlabile subunit levels decreased significantly (p< 0.005), whereas IGFBP-2 detected by immunoblotting increased. Thus IGF-I administration causes changes in IGFBPs which may be important in regulating IGF-1 bioavailability.

scholarly journals Possible role of kallikrein in proteolysis of insulin-like growth factor binding proteins during the oestrous cycle and early pregnancy in pigs

Reproduction ◽  
2001 ◽  
pp. 719-728 ◽  
Author(s):  
RD Geisert ◽  
CS Chamberlain ◽  
KA Vonnahme ◽  
LJ Spicer ◽  
Keyword(s):  
Growth Factor ◽  
Matrix Metalloproteinases ◽  
Early Pregnancy ◽  
Binding Proteins ◽  
Oestrous Cycle ◽  
Tissue Kallikrein ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Igf I ◽  
Conceptus Development

During early pregnancy, pig conceptuses initiate the synthesis of oestrogens and on day 12 their trophoblastic membranes undergo a rapid expansion throughout the uterine horns. The insulin-like growth factor (IGF) system may be involved with conceptus development and steroidogenesis in pigs. Changes in uterine luminal IGF, insulin-like growth factor binding proteins (IGFBPs) and enzymatic activity for cleavage of IGFBPs during the oestrous cycle and early pregnancy were investigated. Uterine luminal content of IGF-I and IGF-II in uterine flushings from pigs on day 12 of pregnancy were two and three times greater, respectively, compared with uterine flushings collected from gilts during the oestrous cycle. Both IGF-I and -II content decreased on day 15 of gestation but content of IGF-II in uterine flushings remained three times greater than that of cyclic gilts. IGFBP-2 and -3 were the predominant binding proteins present in uterine flushings during days 0-10 of the oestrous cycle or day 10 of pregnancy. No IGFBPs were detected in the uterine flushings of either cyclic or pregnant pigs after day 10 by ligand blotting. Incubation of [125I]-labelled IGFBPs with various protease inhibitors indicated that cleavage of [125I]-labelled IGFBP-2 and -3 in uterine flushings involved serine proteases such as tissue kallikrein and matrix metalloproteinases. The results of the present study indicate that an increase in tissue kallikrein activity on day 12 of the oestrous cycle and pregnancy in pigs can directly, or indirectly through activation of matrix metalloproteinases, cleave IGFBP-2 and -3, thus allowing uterine release of IGF-I and -II in the uterine lumen to stimulate conceptus development.

Insulin-like growth factor-binding proteins in tissue fluids from the lamb

1991 ◽  
Vol 129 (1) ◽  
pp. 59-68 ◽  
Author(s):  
A. P. D. Lord ◽  
A. A. Martin ◽  
P. E. Walton ◽  
F. J. Ballard ◽  
L. C. Read
Keyword(s):  
Growth Factor ◽  
Binding Proteins ◽  
Specific Binding ◽  
Binding Protein ◽  
Extracellular Fluid ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Igf I ◽  
Acid Labile Subunit

ABSTRACT Heparinized samples of plasma, cerebrospinal fluid (CSF) and lymph from intestinal, prescapular and popliteal lymph nodes were collected from young lambs in order to characterize and compare the insulin-like growth factor-binding proteins (IGFBPs) in extracellular fluids with those from the circulation. Prior to collection and analysis, the superiority of heparin for plasma preparation was established over EDTA and citrate or the use of serum, according to the extent of IGF-I and IGF-II binding achieved in the high molecular mass IGFBP region in vitro. The IGFBPs were characterized by ligand blotting and competitive binding techniques using radiolabelled IGF-I, IGF-II and the truncated IGF analogue, des(1–3)IGF-I, as well as by ligand blotting of fractions after Superose 6 chromatography of incubations of fluids with labelled factors. This combined analysis demonstrated an IGF-II-specific binding protein at approximately 250 kDa that was present in plasma and each lymph type and presumably represented the soluble type-2 IGF receptor; a complex of 130 kDa containing 52 kDa and 46 kDa binding proteins that was labelled by all three IGF peptides was particularly evident in plasma and intestinal lymph and was probably a complex between IGFBP-3 and the acid-labile subunit; and a group of binding proteins that chromatographed as IGF complexes at approximately 50 kDa. This last group contained IGFBP bands of 52, 46, 35, 28 and 23·5 kDa in plasma and all lymphs as well as an IGF-II-specific band of 22 kDa in prescapular and popliteal lymphs. CSF differed qualitatively from plasma and lymph in that the 52/46 kDa IGFBP bands were undetectable in this fluid; the 35 kDa band was the predominant binding protein, and neither this nor the 28, 23·5 and 22 kDa proteins bound des(1–3)IGF-I to any significant extent. The 52,46 and 28 kDa bands in plasma and lymph did bind this ligand. Immunoblots using antisera against bovine IGFBP-2 showed binding at 35 kDa in all fluids as well as several bands at lower molecular masses. Taken together these results show not only marked differences in the binding protein profiles of sheep plasma, lymph and CSF, but both qualitative and quantitative differences between intestinal, prescapular and popliteal lymphs. We speculate that the differences between lymphs may result from tissuespecific release of binding proteins into extracellular fluid. Journal of Endocrinology (1991) 129, 59–68

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