Control of protein and matrix-molecule synthesis in isolated ovine fetal growth-plate chondrocytes by the interactions of basic fibroblast growth factor, insulin-like growth factors-I and -II, insulin and transforming growth factor-β1

1992 ◽  
Vol 133 (3) ◽  
pp. 363-373 ◽  
Author(s):  
D. J. Hill ◽  
A. Logan ◽  
M. McGarry ◽  
D. De Sousa

ABSTRACT Chondrogenesis is thought to be controlled by interactions between circulating anabolic hormones and locally produced peptide growth factors, and involves ordered changes in matrix composition which ultimately allow endochondral calcification. We have used a model of isolated ovine fetal growth-plate chondrocytes to examine the actions and interactions of basic fibroblast growth factor (basic FGF), insulin-like growth factors-I and -II (IGF-I and -II), insulin and transforming growth factor-β1 (TGF-β1) on total protein, collagen or non-collagenous protein and sulphated glycosaminoglycan synthesis. These parameters were determined by assessment of the incorporation by monolayer cultures of early passage chondrocytes of [3H]leucine, [14C]proline and [35S]sulphate respectively, followed by partial molecular characterization. Basic FGF enhanced total protein synthesis with a half-maximal effective concentration of 270 ± 60 pmol/l (mean ± s.e.m., four animals) and was sixfold more active on a molar basis than IGF-I or insulin, and 28-fold more active that IGF-II which is the endogenously synthesized IGF. The actions of basic FGF were additive to those of IGF-I or insulin. More detailed analysis of extracellular-matrix component synthesis showed that basic FGF, IGF-I and insulin each caused significant increases in the synthesis of collagen and sulphated glycosaminoglycans. TGF-β1 had no effect on total protein synthesis by chondrocytes when present alone at concentrations of 200 pmol/l or less, but was inhibitory at 400 pmol/l. However, the use of this parameter masked a stimulatory action of 50 or 100 pmol TGF-β1 on sulphated glycosaminoglycan synthesis and a relative shift in the ratio of collagen: non-collagenous protein synthesis in favour of the former. A synergistic interaction existed between TGF-β1 (20–100 pmol/l) and basic FGF which potentiated total protein and collagen synthesis, and their actions on sulphated glycosaminoglycan production were additive. The same concentrations of TGF-β1 inhibited the ability of IGF-I or insulin to stimulate total protein or collagen synthesis, but were additive to their stimulatory effects on sulphated glycosaminoglycan synthesis. The results suggest that matrix-molecule composition and the anabolic status of the epiphyseal growth-plate may be modulated in utero by multiple interactions between peptide growth factors produced locally, such as basic FGF, IGF-II and TGF-β1, and circulating hormones such as insulin and IGF-I. Journal of Endocrinology (1992) 133, 363–373

1997 ◽  
Vol 273 (3) ◽  
pp. C843-C851 ◽  
Author(s):  
H. A. Franch ◽  
P. V. Curtis ◽  
W. E. Mitch

The combination of epidermal growth factor (EGF) plus transforming growth factor-beta 1 (TGF-beta 1) causes hypertrophy in renal epithelial cells. One mechanism contributing to hypertrophy is that EGF induces activation of the cell cycle and increases protein synthesis, whereas TGF-beta 1 prevents cell division, thereby converting hyperplasia to hypertrophy. To assess whether suppression of proteolysis is another mechanism causing hypertrophy induced by these growth factors, we measured protein degradation in primary cultures of proximal tubule cells and in cultured NRK-52E kidney cells. A concentration of 10(-8) M EGF alone or EGF plus 10(-10) M TGF-beta 1 decreased proteolysis by approximately 30%. TGF-beta 1 alone did not change protein degradation. Using inhibitors, we examined which proteolytic pathway is suppressed. Neither proteasome nor calpain inhibitors prevented the antiproteolytic response to EGF + TGF-beta 1. Inhibitors of lysosomal proteases eliminated the antiproteolytic response to EGF + TGF-beta 1, suggesting that these growth factors act to suppress lysosomal proteolysis. This antiproteolytic response was not caused by impaired EGF receptor signaling, since lysosomal inhibitors did not block EGF-induced protein synthesis. We conclude that suppression of lysosomal proteolysis contributes to growth factor-mediated hypertrophy of cultured kidney cells.


1994 ◽  
Vol 267 (6) ◽  
pp. E990-E1001 ◽  
Author(s):  
M. Slater ◽  
J. Patava ◽  
K. Kingham ◽  
R. S. Mason

Human fetal osteoblast-like cells formed a regular multilayered structure in vitro with an extensive collagen-based extracellular matrix. With colloidal gold immunocytochemistry, labels for alkaline phosphatase and osteocalcin were distributed in a relatively diffuse pattern, in contrast to the bone growth factors, insulin-like growth factors I and II (IGF-I and IGF-II), transforming growth factor-beta 1 (TGF-beta 1), and basic fibroblast growth factor, which were colocalized in the collagenous matrix of the multilayer. The inclusion of 17 beta-estradiol (10(-11) to 10(-9) M) in the culture medium increased multilayer depths, increased labeling for IGF-I, IGF-II, and TGF-beta 1, and resulted in earlier detection of TGF-beta 1 label. In contrast, the increase in multilayer depth resulting from treatment with human platelets, an exogenous source of growth factors, was not accompanied by an increase in matrix IGF-I, IGF-II, or TGF-beta 1 label, suggesting a particular effect of estradiol to facilitate this process. Because growth factors in bone matrix may act as coupling agents when released during resorption, reduced growth factor incorporation in the presence of reduced sex steroid concentrations may lead to uncoupling of resorption and subsequent formation.


2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Anna Zairi ◽  
Theodoros Lambrianidis ◽  
Ourania Pantelidou ◽  
Serafim Papadimitriou ◽  
Dimitrios Tziafas

The aim of this study was the comparative evaluation of inflammatory reactions and tissue responses to four growth factors, or mineral trioxide aggregate (MTA), or a zinc-oxide-eugenol-based cement (IRM) as controls, when used for the repair of furcal perforations in dogs’ teeth. Results showed significantly higher inflammatory cell response in the transforming growth factorβ1 (TGFβ1) and zinc-oxide-eugenol-based cement (IRM) groups and higher rates of epithelial proliferation in the TGFβ1, basic fibroblast growth factor (bFGF), and insulin growth factor-I (IGF-I) groups compared to the MTA. Significantly higher rates of bone formation were found in the control groups compared to the osteogenic protein-1 (OP-1). Significantly higher rates of cementum formation were observed in the IGF-I and bFGF groups compared to the IRM. None of the biologically active molecules can be suggested for repairing furcal perforations, despite the fact that growth factors exerted a clear stimulatory effect on cementum formation and inhibited collagen capsule formation. MTA exhibited better results than the growth factors.


2002 ◽  
Vol 283 (4) ◽  
pp. F707-F716 ◽  
Author(s):  
Elizabeth Gore-Hyer ◽  
Daniel Shegogue ◽  
Malgorzata Markiewicz ◽  
Shianlen Lo ◽  
Debra Hazen-Martin ◽  
...  

Transforming growth factor-β (TGF-β) and connective tissue growth factor (CTGF) are ubiquitously expressed in various forms of tissue fibrosis, including fibrotic diseases of the kidney. To clarify the common and divergent roles of these growth factors in the cells responsible for pathological extracellular matrix (ECM) deposition in renal fibrosis, the effects of TGF-β and CTGF on ECM expression in primary human mesangial (HMCs) and human proximal tubule epithelial cells (HTECs) were studied. Both TGF-β and CTGF significantly induced collagen protein expression with similar potency in HMCs. Additionally, α2(I)-collagen promoter activity and mRNA levels were similarly induced by TGF-β and CTGF in HMCs. However, only TGF-β stimulated collagenous protein synthesis in HTECs. HTEC expression of tenascin-C (TN-C) was increased by TGF-β and CTGF, although TGF-β was the more potent inducer. Thus both growth factors elicit similar profibrogenic effects on ECM production in HMCs, while promoting divergent effects in HTECs. CTGF induction of TN-C, a marker of epithelial-mesenchymal transdifferentiation (EMT), with no significant induction of collagenous protein synthesis in HTECs, may suggest a more predominant role for CTGF in EMT rather than induction of excessive collagen deposition by HTECs during renal fibrosis.


1989 ◽  
Vol 122 (2) ◽  
pp. 565-571 ◽  
Author(s):  
J. A. Roe ◽  
J. M. M. Harper ◽  
P. J. Buttery

ABSTRACT Methods were developed for the isolation and culture of satellite cells from adult sheep muscle. Differentiated cultures of these cells were used to investigate the effects of four hormones and growth factors on protein synthesis and degradation. Insulin was found to have no effect except at supraphysiological concentrations (100 nmol/l and 1 μmol/l) where it is probably cross-reacting with the insulin-like growth factor (IGF) type-I receptor. IGF-I was found to be anabolic at lower concentrations (1–3 nmol/l). Epidermal growth factor (EGF) had a smaller effect on protein synthesis and degradation than insulin or IGF-I. The specific activity of the muscle-specific enzyme creatine phosphokinase (CPK) was increased by treatment with EGF. When both IGF-I and EGF were present in the test media an additive effect on protein synthesis was observed. However, no additive effect of IGF-I and insulin was noted. No effects of bovine GH were seen. Journal of Endocrinology (1989) 122, 565–571


1994 ◽  
Vol 267 (5) ◽  
pp. G843-G850 ◽  
Author(s):  
S. Oguchi ◽  
W. A. Walker ◽  
I. R. Sanderson

Previous reports have shown that gastrointestinal epithelial cells produce insulin-like growth factor-binding proteins (IGF-BP), which modulate the actions of IGF. This study aims to examine the relationship between differentiation and IGF-BP secretion by human intestinal epithelial cells and the effect of growth factors on their production. Caco-2 cells were cultured in serum-free media. IGF-BP secretion into the incubation media was analyzed by Western ligand blotting and immunoblotting. Caco-2 cells produced IGF-BP-2, IGF-BP-3, and IGF-BP-4. Secretion of IGF-BP-2 and IGF-BP-3 increased with differentiation, but IGF-BP-4 secretion diminished. The effect of exogenous growth factors on IGF-BP secretion was maximal at earlier stages of differentiation. IGF-I stimulated mainly IGF-BP-3 production, but epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) stimulated predominantly IGF-BP-4 secretion. Adding an anti-EGF receptor antibody to block autocrine TGF-alpha activity inhibited IGF-BP-4 production but stimulated IGF-BP-2 and IGF-BP-3. In conclusion, the profile of IGF-BP secretion changes with differentiation. IGF-I and EGF (or TGF-alpha) stimulate different types of IGF-BP, with autocrine TGF-alpha activity being a factor affecting IGF-BP production during differentiation.


2000 ◽  
Vol 167 (2) ◽  
pp. 331-338 ◽  
Author(s):  
T Leinskold ◽  
TE Adrian ◽  
U Arnelo ◽  
J Larsson ◽  
J Permert

Insulin-like growth factor-I (IGF-I) has been demonstrated to exert a nitrogen sparing effect, both experimentally and in patients after abdominal surgery. IGF-I is a major mediator for the anabolic effects of growth hormone (GH). Whether elevated circulating IGF-I levels are the sole mediator of the anabolic effects following GH has not been clarified. IGF-I influences glucose metabolism, both through its own specific receptor and by activating the insulin receptor, and has also been proposed to influence pancreatic islet secretion directly. In the present study, the postoperative effects of IGF-I on plasma levels of other gastrointestinal and pancreatic islet hormones and growth factors were measured in patients after abdominal surgery. Fifteen patients who were candidates for large bowel resection were randomly divided into two groups: IGF-I-treated (n=8) and placebo-treated (n=7). The IGF-I group received daily two s.c. injections of human recombinant IGF-I (80 microg/kg body weight) for five days, beginning on the morning of the first postoperative day. The other group received placebo injections. Fasting plasma levels of gastrointestinal growth factors (epidermal growth factor, transforming growth factor-alpha, IGF-II), gastrointestinal hormones (gastrin, enteroglucagon, peptide YY), and islet hormones (insulin, islet amyloid polypeptide (IAPP) and pancreatic glucagon) were determined by RIA preoperatively and after five days of treatment. No significant effects of IGF-I on other growth factors or gastrointestinal hormones were seen. A marked increase in plasma insulin postoperatively compared with the preoperative levels (42+/-3 vs 61+/-5 pM, P<0.05) was seen in the placebo group, whereas the postoperative levels in the IGF-I-treated patients remained unchanged (44+/-3 vs 45+/-4 pM). A similar pattern was observed for IAPP and cortisol concentrations. No differences in glucagon concentrations were seen. In conclusion, these results suggest that IGF-I does not influence production of other gastrointestinal hormones thought to be involved in alimentary growth or pancreatic glucagon. In contrast, IGF-I caused a marked reduction of insulin and IAPP secretion. The inhibition of beta-cell secretion could be direct or, alternatively, could involve an improvement in postoperative insulin resistance, perhaps by reducing serum cortisol.


1991 ◽  
Vol 131 (2) ◽  
pp. 203-209 ◽  
Author(s):  
S. C. Butterwith ◽  
C. Goddard

ABSTRACT Adipose tissue growth can occur by both hypertrophy and hyperplasia. The capacity for adipocyte hyperplasia in vivo resides in a population of fibroblast-like adipocyte precursor cells but the regulation of the proliferation of these cells by growth factors has not been well characterized. This study was designed to determine the effects of the insulin-like growth factors (IGF-I and IGF-II), platelet-derived growth factor (PDGF) and transforming growth factor-β1 (TGF-β1) added alone or together on the proliferation of primary adipocyte precursor cells in vitro. Adipocyte precursor cell proliferation measured by [3H]thymidine incorporation into DNA was stimulated by all of these growth factors and was particularly marked with PDGF. IGF-I or IGF-II added together with TGF-β1 produced a greater than additive response and the effect of PDGF was synergistic with that of IGF-I at certain concentrations. Stimulation of proliferation of some cell types by TGF-β has been linked to the secondary production of PDGF but the evidence we have suggests that this is unlikely in chicken adipocyte precursors. DNA synthesis in response to TGF-β1 required only a short exposure to the peptide, and conditioned medium from chicken adipocyte precursor cells previously exposed to TGF-β had no effect on DNA synthesis when added to fresh batches of cells. Addition of TGF-β1 together with PDGF produced a synergistic effect whereas an additive effect would be expected if PDGF mediated the effect of TGF-β1. IGF-I mRNA is expressed in the Ob 1771 preadipocyte cell line during differentiation, in stromalvascular cells from adipose tissue, and TGF-β mRNA is expressed in both proliferating and differentiating 3T3-L1 preadipocytes. Together with the data presented here, this would indicate that these peptides have a role in adipocyte development by an autocrine or paracrine mechanism although the source of PDGF in vivo is at present unknown. Journal of Endocrinology (1991) 131, 203–209


1995 ◽  
Vol 13 (5) ◽  
pp. 761-768 ◽  
Author(s):  
S. Jingushi ◽  
S. P. Scully ◽  
M. E. Joyce ◽  
Y. Sugioka ◽  
M. E. Bolander

1995 ◽  
Vol 10 (4) ◽  
pp. 216-220 ◽  
Author(s):  
R. McWilliam ◽  
R.E. Leake ◽  
J.R.T. Coutts

The levels of oestradiol (E2), progesterone (P4), transforming growth factor a (TGFa), transforming growth factor β2 (TGFβ2), insulin-like growth factor I (IGF-I), platelet-derived growth factor AB (PDGF-AB) and epidermal growth factor (EGF) were measured in follicular fluids obtained from patients undergoing ovarian stimulation as part of an in vitro fertilisation program. Each of the substances was detected in all of the fluid samples tested, except TGFα (which was detected in 90% of samples tested), PDGF-AB (70%) and EGF (2%). Comparisons were made between each of these factors, follicular maturity, successful oocyte recovery and the outcome of fertilisation and embryo transfer. No statistically significant correlations were found. The presence of receptors for EGF, IGF-I and PDGF in extracts from granulosa-luteal cells isolated from follicular fluids was detected by means of Western blotting. The co-localisation of these growth factors and their receptors within the ovarian follicle suggests a likely role in control of follicular development.


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