scholarly journals IGFBP-1 expression is reduced in human type 2 diabetic glomeruli and modulates β1-integrin/FAK signalling in human podocytes

Diabetologia ◽  
2021 ◽  
Author(s):  
Abigail C. Lay ◽  
Lorna J. Hale ◽  
Holly Stowell-Connolly ◽  
Robert J. P. Pope ◽  
Viji Nair ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Igf Binding Proteins ◽  
Impedance Sensing ◽  
Human Type ◽  
Early Stages ◽  
Igf Binding ◽  
Phosphoinositide 3 Kinase ◽  
End Stage

AbstractAims/hypothesisPodocyte loss or injury is one of the earliest features observed in the pathogenesis of diabetic kidney disease (DKD), which is the leading cause of end-stage renal failure worldwide. Dysfunction in the IGF axis, including in IGF binding proteins (IGFBPs), is associated with DKD, particularly in the early stages of disease progression. The aim of this study was to investigate the potential roles of IGFBPs in the development of type 2 DKD, focusing on podocytes.MethodsIGFBPexpression was analysed in the Pima DKD cohort, alongside data from the Nephroseq database, and in ex vivo human glomeruli. Conditionally immortalised human podocytes and glomerular endothelial cells were studied in vitro, where IGFBP-1 expression was analysed using quantitative PCR and ELISAs. Cell responses to IGFBPs were investigated using migration, cell survival and adhesion assays; electrical cell-substrate impedance sensing; western blotting; and high-content automated imaging.ResultsData from the Pima DKD cohort and from the Nephroseq database demonstrated a significant reduction in glomerularIGFBP-1in the early stages of human type 2 DKD. In the glomerulus, IGFBP-1 was predominantly expressed in podocytes and controlled by phosphoinositide 3-kinase (PI3K)–forkhead box O1 (FoxO1) activity. In vitro,IGFBP-1 signalled to podocytes via β1-integrins, resulting in increased phosphorylation of focal-adhesion kinase (FAK), increasing podocyte motility, adhesion, electrical resistance across the adhesive cell layer and cell viability.Conclusions/interpretationThis work identifies a novel role for IGFBP-1 in the regulation of podocyte function and that the glomerular expression ofIGFBP-1is reduced in the early stages of type 2 DKD, via reduced FoxO1 activity. Thus, we hypothesise that strategies to maintain glomerular IGFBP-1 levels may be beneficial in maintaining podocyte function early in DKD.Graphical abstract

scholarly journals Differential Activation of CD8+Tumor-Specific Tc1 and Tc2 Cells by an IL-10-Producing Murine Plasmacytoma

1998 ◽  
Vol 6 (3-4) ◽  
pp. 331-342 ◽  
Author(s):  
Christoph Specht ◽  
Hans-Gerd Pauels ◽  
Christian Becker ◽  
Eckehart Kölsch
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Tumor Cells ◽  
T Cell Subsets ◽  
Early Stages ◽  
Specific Tolerance

The involvement of counteractiveCD8+T-cell subsets during tumor-specific immune responses was analyzed in a syngeneic murine plasmacytoma model.CD8+Tc cells against the immunogenic IL-10-producing BALB/c plasmacytoma ADJ-PC-5 can be easily induced by immunization of BALB/c mice with X-irradiated ADJ-PC-5 tumor cellsin vivoandin vitro. However, the failure of recipient mice to mount a protective Tc response against the tumor during early stages of a real or simulated tumor growth is not due to immunological ignorance, but depends on the induction of tumor-specific tolerance, involving a population of tumorinducedCD8+T cells that are able to inhibit the generation of tumor-specific Tc cells in a primary ADJ-PC-5-specific MLTC, using IFN-γas a suppressive factor. Whereas most longterm cultivated CD8+ADJ-PC-5-specific Tc lines produce type-1 cytokines on stimulation, at least two of them, which were derived from a primary MLTC, display a type-2 cytokine spectrum. Furthermore, the primaryin vitroTc response against ADJ-PC-5 cells shows characteristics of a Tc2 response. The Tc response is strictly depending on tumor-derived IL-10.CD8+Tc cells that are induced in a primary MLTC do not produce IFN-γ, and the tumor-specific Tc response is enhanced by IL-4 but suppressed by IFN-γor IL-12. In contrast, ADJ-PC- 5-specificCD8+Tc cells from immunized mice are IFN-γproducing Tc1 cells. Since the primaryin vitroTc response against the tumor is suppressed even by the smallest numbers of irradiated ADJ-PC-5-specific Tc1 cells via IFN-γthese Tc1 cells behave similar to the suppressiveCD8+T cells that are induced during early stages of ADJ-PC-5 tumorigenesis.

scholarly journals PAPA-1 Is a Nuclear Binding Partner of IGFBP-2 and Modulates Its Growth-Promoting Actions

2009 ◽  
Vol 23 (2) ◽  
pp. 169-175 ◽  
Author(s):  
Kenichi Miyako ◽  
Laura J. Cobb ◽  
Malik Francis ◽  
Alden Huang ◽  
Bonnie Peng ◽  
...  
Keyword(s):  
Glutathione S Transferase ◽  
Mouse Embryonic Fibroblasts ◽  
Promoting Effect ◽  
Embryonic Fibroblasts ◽  
Igf Binding Proteins ◽  
Cellular Effects ◽  
Igf Binding ◽  
Growth Promoting ◽  
Interfering Rna

Abstract IGF-binding proteins (IGFBPs) have multiple cellular effects, which occur by both IGF-dependent and -independent mechanisms. IGFBP-2 is involved in the regulation of both normal and carcinogenic cell growth. To further understand the actions of IGFBP-2, we carried out a yeast two-hybrid screen to search for intracellular partner proteins using a human prostate cDNA library. We isolated Pim-1-associated protein-1 (PAP-1)-associated protein-1 (PAPA-1) as an IGFBP-2-binding protein, whose expression and subcellular localization is regulated by both IGFBP-2 and androgens. Coimmunoprecipitation and glutathione S-transferase pull-down assay confirmed the interaction in vitro, and confocal microscopy showed the colocalization of IGFBP-2 and PAPA-1 in the nucleus. Suppression of PAPA-1 by small interfering RNA treatment enhanced the growth-promoting effect of IGFBP-2. Conversely, IGFBP-2-promoted bromodeoxyuridine incorporation into LNCaP cells was abrogated by the simultaneous overexpression of myc-hPAPA-1. Mouse embryonic fibroblasts from IGFBP-2 knockout mouse showed diminished growth activity compared with wild type, and expression of FLAG-mPAPA-1 decreased cell proliferation in IGFBP-2 knockout, but not control mouse embryonic fibroblasts. These studies suggest that the growth-promoting role of IGFBP-2 in prostate cancer is inhibited by its intracellular interaction with PAPA-1.

scholarly journals Effects of IGF-I bioavailability on bovine preantral follicular development in vitro

Reproduction ◽  
2007 ◽  
Vol 133 (6) ◽  
pp. 1121-1128 ◽  
Author(s):  
Fiona H Thomas ◽  
Bruce K Campbell ◽  
David G Armstrong ◽  
Evelyn E Telfer
Keyword(s):  
Follicular Development ◽  
Follicle Development ◽  
Dependent Manner ◽  
Igf Binding Proteins ◽  
Preantral Follicles ◽  
Follicle Diameter ◽  
Igf I ◽  
Igf Binding ◽  
Development In Vitro

The aim of this study was to determine the effect of regulation of IGF-I bioavailability on preantral follicle development in vitro. Bovine preantral follicles were cultured for 6 days in serum-free medium with increasing doses of Long R3 (LR3) IGF-I (an analog with low affinity for IGF-binding proteins (IGFBPs)), or human recombinant IGF-I (hrIGF-I). Follicle diameter and estradiol production were measured every second day. On day 6, ratios of oocyte/follicle diameter and oocyte morphology were assessed by histological examination, and IGFBP-2 and -3 were detected by immunocytochemistry and in situ hybridization respectively. Both types of IGF-I increased follicle diameter in a dose-dependent manner (P < 0.05) and increased estradiol production over control levels (P < 0.05). However, follicles treated with LR3 IGF-I and the highest concentration of hrIGF-I (1000 ng/ml) had smaller oocyte/follicle ratios, and increased oocyte degeneration, compared with controls or follicles treated with physiological concentrations of hrIGF-I (P < 0.05). IGFBPs were detected in cultured preantral follicles, indicating a requirement for regulation of IGF bioavailability during the early stages of follicular development. Specifically, IGFBP-3 mRNA was found to be expressed in oocytes, and IGFBP-2 immunoreactivity was detected in oocytes and granulosa cells of cultured follicles. In summary, the regulation of IGF-I bioavailability by IGFBPs is necessary for the co-ordination of oocyte and follicle development in vitro.

scholarly journals GH/IGF e neoplasia: o que há de novo nesta associação

2005 ◽  
Vol 49 (5) ◽  
pp. 833-842 ◽  
Author(s):  
Angela M. Spinola e Castro ◽  
Gil Guerra-Júnior
Keyword(s):  
Growth Factors ◽  
Binding Proteins ◽  
De Novo ◽  
Igf Binding Proteins ◽  
Igf I ◽  
Ciclo Celular ◽  
Igf Binding ◽  
Insulin Like Growth Factors

Estudos in vitro e em animais sugerem que os membros do sistema insulin-like growth factors (IGFs), incluindo IGF-I, IGF-II, receptores de IGF-I e IGF-II (IGF-IR e IGF-IIR), e as IGF-binding proteins (IGFBPs) podem ter um importante envolvimento no desenvolvimento e na progressão de neoplasias. Mais especificamente, as IGFs promovem a progressão do ciclo celular e inibem a apoptose tanto por ação direta com outros fatores de crescimento como por ação indireta interagindo com outros sistemas moleculares intracelulares envolvidos na promoção e/ou progressão do câncer. Além disso, inúmeros estudos epidemiológicos têm sugerido que concentrações elevadas das IGFs, independente das alterações nas IGFBPs, podem estar associadas a um aumento no risco de desenvolver determinadas neoplasias. Esta revisão tem como objetivo apresentar o envolvimento do sistema IGF na regulação tumoral, os principais estudos epidemiológicos realizados e o risco de desenvolvimento de neoplasia em pacientes (com ou sem história pessoal de neoplasia prévia) que receberam hormônio de crescimento (rhGH). É importante salientar que o uso clínico de rhGH, nas indicações aprovadas internacionalmente, é seguro e não existem evidências, até o momento, da associação com o desenvolvimento de neoplasias.

Genomic engineering of adipocytes with CRISPR/Cas9 delivery particles for ex vivo therapeutic approach for type 2 diabetes

2021 ◽  
Author(s):  
Εμμανουέλα Τσαγκαράκη
Keyword(s):  
Type 2 Diabetes ◽  
Therapeutic Approach ◽  
Ex Vivo ◽  
Knock Out ◽  
Genomic Engineering ◽  
Fat Depots

Η παχυσαρκία και ο διαβήτης τύπου 2 (ΔΤ2) σχετίζονται με διαταραχές στην ομοιόσταση της γλυκόζης και των λιπιδίων η οποία ρυθμίζεται από την ινσουλίνη και προκαλεί σοβαρές επιπλοκές συμπεριλαμβανομένων καρδιαγγειακών νοσημάτων και στεατοηπατίτιδας. Ο συστημικός μεταβολισμός της γλυκόζης ρυθμίζεται από τους διακριτούς λιπώδεις ιστούς (fat depots), στις οποίες συμπεριλαμβάνονται δύο κυρίως τύποι λιπώδους ιστού το λευκό λίπος και το φαιό (ή καφέ) λίπος. Το μεν λευκό λίπος αποτελείται από τα «λευκά» λιποκύτταρα και έχει ρόλο αποθήκευσης της ενέργειας σε μορφή λιπιδίων ενώ το φαιό λίπος αποτελείται από τα «φαιά» και «μπεζ» λιποκύτταρα. Tα κύτταρα αυτά καταναλώνουν την αποθηκευμένη ενέργεια για την παραγωγή θερμότητας και εκφράζουν την πρωτεΐνη αποσύζευξης 1 (UCP1) καθώς και πλήθος εκκρινόμενων παραγόντων που ευνοούν τον μεταβολισμό. Έχει περιγραφή στη βιβλιογραφία ότι η μεταμόσχευση φαιού λιπώδους ιστού ή ποντικίσιων ή αθανατοποιημένων ανθρώπινων φαιών λιποκυττάρων σε παχύσαρκους μύες βελτιώνει την ανοχή στη γλυκόζη. Ωστόσο, η εφαρμογή μιας ανάλογης θεραπευτικής παρέμβασης στον άνθρωπο δεν έχει καταστεί δυνατή καθώς η διαθεσιμότητα των πρωτογενών ανθρώπινων φαιών/μπεζ λιποκυττάρων είναι εξαιρετικά περιορισμένη. Στην παρούσα διατριβή, χρησιμοποίησα μεθόδους πολλαπλασιασμού σε μεγάλη κλίματα ανθρώπινων πρόγονων λιποκυττάρων από εξαιρετικά μικρά δείγματα ανθρώπινου λιπώδους ιστού. Στα ανθρώπινα πρόδρομα λιποκύτταρα, παράλληλα με τα ποντικίσια, εφάρμοσα τροποποίηση του γονιδιώματος με τη χρήση ομαδοποιημένων με τακτά μεσοδιαστήματα σύντομων παλινδρομικών μοτίβων (CRISPR). O στόχος αυτής της γονιδιακής τροποποίησης είναι να απενεργοποιήσει γονίδια που φυσιολογικά παρεμποδίζουν τη μετατροπή των λιποκυττάρων από λευκά σε φαιά. Συνεπώς, η απώλεια της λειτουργικότητας αυτών των γονιδίων αναμένεται να προκαλέσει την μετατροπή των λευκών λιποκυττάρων σε φαιά που είναι ωφέλιμα για τον μεταβολισμό της γλυκόζης. Σημαντικοί δευτερεύοντες στόχοι της στρατηγικής της θεραπείας είναι η παράκαμψη της ανοσογονικότητας των συστατικών CRISPR και της γονιδιακής τροποποίησης σε ανεπιθύμητους ιστούς καθώς και η ελαχιστοποίηση της ανεπιθύμητης τροποποίησης σε περιοχές του γονιδιώματος εκτός των στοχευμένων. Στην παρούσα εργασία, ανέπτυξα και μεγιστοποίησα τη μέθοδο ex vivo μεταφοράς στα κύτταρα – στόχους (λιποκύτταρα) των συμπλεγμάτων στρεπτοκοκκικού Cas9 ενζύμου και στου οδηγού sgRNA, ούτως ώστε να επιτυγχάνεται η ταχύτατη διάσπασή τους αμέσως μετά την τροποποίηση του γονιδίου – στόχο. Για τη μεταφορά των συμπλεγμάτων αυτών, χρησιμοποιήθηκε η μέθοδος της ηλεκτροδιάτρησης με αποτελεσματικότητα τροποποίησης που πλησιάζει το 100%. Κατόπιν ελέγχου πλήθους υποψηφίων γονιδίων – στόχων που αναφέρονται στη βιβλιογραφία, εντοπίστηκε ως ο πλέον υποσχόμενος στόχος το γονίδιο της πρωτεΐνης 1 που αναγνωρίζει πυρηνικούς υποδοχείς (NRIP1). Τα λιποκύτταρα στα οποία απενεργοποιήθηκε το Nrip1 γονίδιο (NRIP1 Knock-out, NRIP1KO) επάγουν την έκφραση ενός «φαιού» γονιδιακού προφίλ το οποίο συμπεριλαμβάνει την πρωτεΐνη UCP1 και ορισμένους εκκρινόμενους παράγοντες. Στη συνέχεια, χαρακτήρισα in vitro το φαινότυπο των τροποποιημένων κυττάρων με πλήθος δοκιμασιών όπως έκφραση γνωστών γονιδίων που σχετίζονται με τη θερμογένεση, μιτοχονδριακή αναπνοή, οξέωση λιπιδίων, εκκρινομένους παράγοντες, δοκιμασία κατανάλωση οξυγόνου, έκφραση της πρωτεΐνης UCP1, τόσο στο ποντικίσια όσο και στο ανθρώπινα κύτταρα. Τέλος, τα βελτιστοποιημένα με CRISPR ποντικίσια ή ανθρώπινα «φαιά» λιποκύτταρα εμφυτεύθηκαν σε ποντίκια – λήπτες τα οποία λάμβαναν διατροφή εμπλουτισμένη σε λίπος για την πρόκληση διαβήτη τύπου 2. Τα εμφυτεύματα των τροποποιημένων κυττάρων έδειξαν μικρότερη συσσώρευση σωματικού λίπους μικρότερη συσσώρευση τριγλυκεριδίων στο ηπατικό παρέγχυμα καθώς επίσης βελτίωσαν την ανοχή στη γλυκόζη συγκριτικά με τα ποντίκια – μάρτυρες που έλαβαν εμφυτεύματα μη τροποποιημένων λιποκυττάρων. Παράλληλα, όπως απεδείχθη η παρουσία των συστατικών της CRISPR τροποποίησης ήταν παροδική στα κύτταρα-στόχους καθώς η ενδονουκλεάση Cas9 αποδομείται και δεν είναι ανιχνεύσιμη με ηλεκτροφόρηση ολικής πρωτεΐνης πριν τις εμφυτεύσεις. Τα ευρήματα αυτά υποδεικνύουν μια θεραπευτική στρατηγική για τη βελτίωση της ομοιόστασης του μεταβολισμού μέσω της γονιδιακής τροποποίησης με CRISPR ανθρώπινων λιποκυττάρων χωρίς την έκθεση του ασθενούς στα ανοσογόνα και δυνητικά επιβλαβή ένζυμο Cas9 και οδηγό sgRNA και άλλων οχημάτων μεταφοράς των συστατικών CRISPR.

scholarly journals N-Acetylcysteine and Sulodexide Reduce the Prothrombotic Effect of Uremic Serum on the Venous Endothelial Cells

2019 ◽  
Vol 44 (2) ◽  
pp. 277-285
Author(s):  
Patrycja Sosinska-Zawierucha ◽  
Beata Mackowiak ◽  
Andrzej Breborowicz
Keyword(s):  
Gene Expression ◽  
Renal Failure ◽  
Endothelial Cells ◽  
Ex Vivo ◽  
Secretory Activity ◽  
Serum Samples ◽  
Uremic Serum ◽  
Uremic Patients ◽  
End Stage

Background/Aims: Thromboembolic episodes are a frequent problem in end stage renal failure patients. The pathomechanism of the disorder is complex, including bioincompatibility of renal replacement therapy, endothelial dysfunction, increased blood level of procoagulant factors and uremic toxins. We studied changes in the functional properties of venous endothelial cells (VEC) in the presence of uremic serum and evaluated their possible modulation by N-acetylcysteine (NAC) or sulodexide (SUL). Methods: Serum samples from 12 uremic patients treated with hemodialysis were studied ex vivo on in vitro cultured VEC. In separate experiments, NAC 1 mmol/L or SUL 0.5 LRU/mL were added to uremic serum samples. Both changes in the gene expression and secretory activity of VEC were studied. Results: Uremic serum increased the expression of the following genes: IL6 +97%, p < 0.002; VEGF +28%, p < 0.002; vWF +47%, p < 0.002; PECAM +76%, p < 0.002; ICAM-1 +275%, p < 0.002; t-PA +96%, p < 0.002. Changes in gene expression were reflected by the increased secretory activity of VEC treated with the uremic serum. Exposure of VEC to uremic serum supplemented with NAC or SUL resulted in weaker stimulation of the studied genes’ expression. Also, secretion of the studied solutes, with the exception of ICAM-1, was reduced in the presence of NAC: IL6 –34%, p < 0.01; VEGF –40%, p < 0.005; vWF –25%, p < 0.001; t-PA –47%, p < 0.01, and MMP9 –37%, p < 0.001. SUL reduced the uremic serum-induced secretion of all solutes: IL6 –24%, p < 0.05; ICAM-1 –43%, p < 0.01; VEGF –38%, p < 0.01; vWF –23%, p < 0.01; t-PA –49%, p < 0.01, and MMP9 –25%, p < 0.05. Conclusions: Uremic serum induces prothrombotic changes in VEC, which may cause a predisposition to thrombotic disorders in patients with renal failure. NAC and SUL reduce the effects of the uremic serum in VEC, which suggests their potential therapeutic application in uremic patients.

Relationships between concentrations of steroids, igf-1 and igf binding proteins during follicular development in the ewe

1995 ◽  
Vol 1995 ◽  
pp. 56-56
Author(s):  
M. Khalid ◽  
W. Haresign
Keyword(s):  
Follicular Fluid ◽  
Biochemical Markers ◽  
Binding Proteins ◽  
Ovarian Function ◽  
Follicular Development ◽  
Physiological Status ◽  
Igf Binding Proteins ◽  
Ovarian Cells ◽  
Igf Binding

Insulin-like growth factor-1 (IGF-1) is one of the potential autocrine/paracrine regulators of ovarian function. Not only do relationships exist between follicular fluid concentrations of IGF-1 and various biochemical markers of follicular differentiation, but IGF-1 has also been shown to stimulate both proliferation and steroidogenesis in ovarian cells in vitro (Adashi et al., 1985). The actions of IGF-1 are thought to be modulated by IGF-binding proteins (IGFBPs). Indeed, follicular growth and atresia in the ewe have been reported to be determined more by changes in IGFBPs than by changes in IGF-1 (Monget et al., 1993). However, in mat particular study, stage of follicular development was determined by follicle size and by microscopic examination of the granulosa cells of individual follicles rather than by biochemical markers of follicle status. The objective of the present study was, therefore, to investigate changes in IGF-1 and IGFBPs levels in follicular fluid and to relate these to the physiological status as determined by steroidogenic content of follicular fluid.

scholarly journals A Versatile Model of Microfluidic Perifusion System for the Evaluation of C-Peptide Secretion Profiles: Comparison Between Human Pancreatic Islets and HLSC-Derived Islet-Like Structures

Biomedicines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 26 ◽  
Author(s):  
Yonathan Gomez ◽  
Victor Navarro-Tableros ◽  
Ciro Tetta ◽  
Giovanni Camussi ◽  
Maria Felice Brizzi
Keyword(s):  
High Glucose ◽  
Ex Vivo ◽  
C Peptide ◽  
Healthy Donors ◽  
Secretion Profile ◽  
Lower Amplitude ◽  
Peptide Secretion ◽  
Perifusion System

A robust and easy-to-use tool for the ex vivo dynamic evaluation of pancreatic islet (PI) function is essential for further development of novel cell-based therapeutic approaches to treating diabetes. Here, we developed four different glucose perifusion protocols (GPPs) in a microfluidic perifusion system (MPS), based entirely on commercially available components. After validation, the GPPs were used to evaluate C-peptide secretion profiles of PIs derived from different donors (healthy, obese, and type 2 diabetic) and from human liver stem-cell-derived islet-like structures (HLSC-ILS). Using this device, we demonstrated that PIs derived from healthy donors displayed a physiological C-peptide secretion profile as characterized by the response to (a) different glucose concentrations, (b) consecutive pulses of high-glucose concentrations, (c) a glucose threshold ranging from 5–8 mM, and (d) a constant high-glucose perifusion in a biphasic manner. Moreover, we were able to detect a dysregulated secretion profile in PIs derived from both obese and type 2 diabetes mellitus (T2DM) donors. Finally, we also evaluated the kinetic secretion profiles of HLSC-ILS, demonstrating that, nonetheless, with a lower amplitude of secretion compared to PI derived from healthy donors, they were already glucose-responsive on day seven post-differentiation. In conclusion, we have provided evidence that our MPS is a versatile device and may represent a valuable tool to study insulin-producing cells in vitro.

Secretion of insulin-like growth factor-I (IGF-I) and IGF-binding proteins from bovine mammary tissue in vitro

1991 ◽  
Vol 128 (2) ◽  
pp. 219-228 ◽  
Author(s):  
P. G. Campbell ◽  
T. C. Skaar ◽  
J. R. Vega ◽  
C. R. Baumrucker
Keyword(s):  
Growth Factor ◽  
Binding Proteins ◽  
Conditioned Media ◽  
Mammary Tissue ◽  
Igf Binding Proteins ◽  
Factor I ◽  
Igf I ◽  
Igf Binding ◽  
Bovine Mammary Tissue

ABSTRACT In vitro, insulin-like growth factor-I (IGF-I) promotes both growth and development of bovine mammary tissue. In vivo, the effects of IGF-I may encompass endocrine, paracrine or autocrine mediation. We addressed the possibility of paracrine/autocrine effects of IGF-I in the mammary gland by examining the in-vitro secretion of IGF-I and IGF-binding proteins (IGFBPs) from bovine mammary tissue. Bovine mammary explants from pregnant non-lactating and lactating non-pregnant animals were found to synthesize and secrete IGF-I and IGFBPs. Mammary acini cultures, representative of mammary secretory epithelia, secreted both IGF-I and IGFBP, but synthesized only IGFBP. Concentrations of IGF-I in conditioned media from explants were 1·54 and 0·72 fmol/μg DNA for pregnant and lactating animals respectively. Concentrations of IGFBPs in conditioned media from explants were similar for both physiological states at 2529 pmol 125I-labelled IGF-I bound/pg DNA. Ligand/Western blotting procedures identified four IGFBPs of 29, 33, 37 and 44 kDa for acini cultures and five IGFBPs of 28, 31, 36, 44 and 46 kDa for explant cultures. Similar affinities for IGF-I and IGF-II were shown by IGFBP, using 125I-labelled recombinant human IGF-I as the competing ligand (median effective dose (ED50) of 0·085 pmol). When 125I-labelled bovine IGF-II was used as the ligand, only bovine IGF-II (ED50 of 0·25 pmol) inhibited binding. The addition of prolactin, insulin and cortisol, with or without GH, did not affect secretion of either IGF-I or IGFBP. This report describes the ability of normal mammary tissue to synthesize and secrete IGF-I and IGFBPs. Journal of Endocrinology (1991) 128, 219–228

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