Effects of growth factors on myogenic differentiation

1989 ◽  
Vol 256 (4) ◽  
pp. C701-C711 ◽  
Author(s):  
J. R. Florini ◽  
K. A. Magri

It has now been well established that the terminal differentiation of muscle cells in culture is subject to control by hormones and growth factors in the incubation medium. Thus far the most potent and most extensively studied agents are fibroblast growth factor (FGF), the insulinlike growth factors (IGFs), and transforming growth factor-beta (TGF-beta). Independent reports from several laboratories have established that both FGF and TGF-beta are potent inhibitors of differentiation and both appear to act at early stages of commitment to differentiation. Stimulation of differentiation by the IGFs (and by insulin at concentrations in the microgram/ml range) has also been observed and confirmed repeatedly. FGF and IGF are mitogenic for muscle cells, and TGF-beta either has no effect or suppresses cell proliferation, so previous generalizations that mitogens inhibit myogenic differentiation are clearly not valid when results with purified agents in well-defined media are considered. Work with oncogenes and specific toxins is beginning to reveal the mechanisms by which these agents might affect differentiation, and there is reason for optimism that an understanding of the molecular events that control terminal differentiation may be attained in the near future.

1990 ◽  
Vol 10 (6) ◽  
pp. 2669-2677
Author(s):  
G E Panganiban ◽  
K E Rashka ◽  
M D Neitzel ◽  
F M Hoffmann

The decapentaplegic (dpp) gene of Drosophila melanogaster is required for pattern formation in the embryo and for viability of the epithelial cells in the imaginal disks. The dpp protein product predicted from the DNA sequence is similar to members of a family of growth factors that includes transforming growth factor beta (TGF-beta). We have produced polyclonal antibodies to a recombinant dpp protein made in bacteria and used a metallothionein promoter to express a dpp cDNA in Drosophila S2 cells. Similar to other proteins in the TGF-beta family, the dpp protein produced by the Drosophila cells was proteolytically cleaved, and both portions of the protein were secreted from the cells. The amino-terminal 47-kilodalton (kDa) peptide was found in the medium and in the proteins adhering to the plastic petri dish. The carboxy-terminal peptide, the region with sequence similarity to the active ligand portion of TGF-beta, was found extracellularly as a 30-kDa homodimer. Most of the 30-kDa homodimer was in the S2 cell protein adsorbed onto the surface of the plastic dish. The dpp protein could be released into solution by increased salt concentration and nonionic detergent. Under these conditions, the amino-terminal and carboxy-terminal portions of dpp were not associated in a stable complex.


Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 635-645 ◽  
Author(s):  
K.M. Stocker ◽  
L. Sherman ◽  
S. Rees ◽  
G. Ciment

In previous studies, we showed that neural crest (NC)-derived cells from embryonic quail dorsal root ganglia (DRG) and peripheral nerve (PN), which do not normally give rise to melanocytes, become committed to melanogenesis following treatment in culture with the phorbol ester drug 12-O-tetradecanoyl phorbol-13-acetate (TPA). These and other observations support the notion that melanocytes and Schwann cells are derived from a common bipotent intermediate in the neural crest lineage—the melanocyte/Schwann cell progenitor. In this study, we test the possibility that peptide growth factors found in the embryonic environment might act similarly to TPA to influence the fates of these cells. DRG and PN explants were cultured in medium supplemented with a variety of growth factors, and then the cultures were examined for the presence of pigment cells. We found that basic fibroblast growth factor (bFGF), but not various other growth factors, induced pigmentation in about 20% of these cultures. When low concentrations of TPA were included in the culture medium, bFGF augmented the TPA-induced pigmentation, significantly increasing the proportion of pigmented cultures. These effects of bFGF were age-dependent, and could be blocked by addition of a bFGF-neutralizing antibody to the culture medium. In contrast to these stimulatory effects of bFGF, transforming growth factor-beta 1 (TGF-beta 1) was found to inhibit the TPA- or bFGF-induced pigmentation of DRG cultures. These data suggest, therefore, that at least some NC-derived cells are responsive to bFGF and TGF-beta 1, and that these growth factors may play an important role in the control of NC cell fate.


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.


1994 ◽  
Vol 303 (3) ◽  
pp. 713-721 ◽  
Author(s):  
G E Ysart ◽  
R M Mason

1. The effect of different batches of fetal bovine serum and of growth factors on [35S]sulphate incorporation into glycosaminoglycans and on UDP-sugar pools in explant cultures of bovine articular cartilage was investigated. 2. [35S]Sulphate incorporation was variably stimulated between 1.2- and 3.5-fold by four different batches of serum. The UDP-glucuronate pool size expanded 4.3-6.5-fold in the presence of serum, even in those cultures in which little stimulation of [35S]sulphate incorporation occurred. The UDP-N-acetylhexosamine and UDP-hexose pools expanded by about 1.5- and 2.0-fold respectively in the presence of serum. UDP-xylose was not detected. 3. Equilibrium-labelling and pulse-chase experiments with D-[1-3H]glucose indicated that the rate of flux through the UDP-sugar pools was unaffected by serum. UDP-hexose, UDP-N-acetylhexosamine and UDP-glucuronate have approximate half-lives (t1/2) of 7, 12 and 3-4 min respectively. At equilibrium, the 3H specific activities of UDP-hexose and UDP-N-acetylhexosamine were very similar but that for the UDP-glucuronate pool was much higher, especially in serum-supplemented cultures. The results suggest that UDP-glucuronate synthesis occurs via a pathway which is independent of the main UDP-hexose pathway. 4. Supplementing cultures with heat-treated serum had no effect on the serum-induced expansion of UDP-sugar pools but stimulation of [35S]sulphate incorporation into glycosaminoglycans was 50% lower than for native serum. Acid-treated serum promoted a 2-fold expansion of the UDP-glucuronate and UDP-N-acetylhexosamine pool over that obtained with native serum but was 20% less effective in stimulating [35S]sulphate incorporation than the latter. Prior dialysis of serum had no effect on its modulatory action on either [35S]sulphate incorporation or on the size of UDP-sugar pools. 5. Insulin-like growth factor 1 (IGF-1), transforming growth factor beta-1 (TGF beta-1), platelet-derived growth factor (PDGF) (BB homodimer) and epidermal growth factor (EGF) all stimulated [35S]sulphate incorporation into glycosaminoglycans as expected. The UDP-glucuronate pool expanded by 1.5- and 2.0-fold in the presence of IGF-1 and TGF beta-1 respectively, and by about 1.8-fold in the presence of PDGF or EGF. None of the factors investigated, or combinations of IGF-1 and TGF beta-1 or IGF-1 and EGF, stimulated expansion of the UDP-glucuronate pool to the same extent as native serum.(ABSTRACT TRUNCATED AT 400 WORDS)


1993 ◽  
Vol 120 (4) ◽  
pp. 995-1002 ◽  
Author(s):  
R Flaumenhaft ◽  
M Abe ◽  
Y Sato ◽  
K Miyazono ◽  
J Harpel ◽  
...  

Transforming growth factor beta (TGF-beta) is released from cells in a latent form consisting of the mature growth factor associated with an aminoterminal propeptide and latent TGF-beta binding protein (LTBP). The endogenous activation of latent TGF-beta has been described in co-cultures of endothelial and smooth muscle cells. However, the mechanism of this activation remains unknown. Antibodies to native platelet LTBP and to a peptide fragment of LTBP inhibit in a dose-dependent manner the activation of latent TGF-beta normally observed when endothelial cells are cocultured with smooth muscle cells. Inhibition of latent TGF-beta activation was also observed when cells were co-cultured in the presence of an excess of free LTBP. These data represent the first demonstration of a function for the LTBP in the extracellular regulation of TGF-beta activity and indicate that LTBP participates in the activation of latent TGF-beta, perhaps by concentrating the latent growth factor on the cell surface where activation occurs.


1991 ◽  
Vol 2 (12) ◽  
pp. 1081-1095 ◽  
Author(s):  
C S Long ◽  
C J Henrich ◽  
P C Simpson

Cardiac nonmyocytes, primarily fibroblasts, surround cardiac myocytes in vivo. We examined whether nonmyocytes could modulate myocyte growth by production of one or more growth factors. Cardiac myocyte hypertrophic growth was stimulated in cultures with increasing numbers of cardiac nonmyocytes. This effect of nonmyocytes on myocyte size was reproduced by serum-free medium conditioned by the cardiac nonmyocytes. The majority of the nonmyocyte-derived myocyte growth-promoting activity bound to heparin-Sepharose and was eluted with 0.75 M NaCl. Several known polypeptide growth factors found recently in cardiac tissue, namely acidic fibroblast growth factor (aFGF), basic FGF (bFGF), platelet-derived growth factor (PDGF), tumor necrosis factor alpha (TNF alpha), and transforming growth factor beta 1 (TGF beta 1), also caused hypertrophy of cardiac myocytes in a dose-dependent manner. However, the nonmyocyte-derived growth factor (tentatively named NMDGF) could be distinguished from these other growth factors by different heparin-Sepharose binding profiles (TNF alpha, aFGF, bFGF, and TGF beta 1) by neutralizing growth factor-specific antisera (PDGF, TNF alpha, aFGF, bFGF, and TGF beta 1), by the failure of NMDGF to stimulate phosphatidylinositol hydrolysis (PDGF and TGF beta 1), and, finally, by the apparent molecular weight of NMDGF (45-50 kDa). This nonmyocyte-derived heparin-binding growth factor may represent a novel paracrine growth mechanism in myocardium.


1989 ◽  
Vol 109 (1) ◽  
pp. 309-315 ◽  
Author(s):  
Y Sato ◽  
D B Rifkin

When a confluent monolayer of bovine aortic endothelial (BAE) cells is wounded with a razor blade, endothelial cells (ECs) spontaneously move into the denuded area. If bovine pericytes or smooth muscle cells (SMCs) are plated into the denuded area at low density, they block the movement of the ECs. This effect is dependent upon the number of cells plated into the wound area and contact between ECs and the plated cells. Antibodies to transforming growth factor-beta 1 (TGF-beta 1) abrogate the inhibition of BAE cell movement by pericytes or SMCs. TGF-beta 1, if added to wounded BAE cell monolayers, also inhibits cell movement. When cultured separately, BAE cells, pericytes, and SMCs each produce an inactive TGF-beta 1-like molecule which is activated in BAE cell-pericyte or BAE cell-SMC co-cultures. The activation appears to be mediated by plasmin as the inhibitory effect on cell movement in co-cultures of BAE cells and pericytes is blocked by the inclusion of inhibitors of plasmin in the culture medium.


1990 ◽  
Vol 10 (6) ◽  
pp. 2669-2677 ◽  
Author(s):  
G E Panganiban ◽  
K E Rashka ◽  
M D Neitzel ◽  
F M Hoffmann

The decapentaplegic (dpp) gene of Drosophila melanogaster is required for pattern formation in the embryo and for viability of the epithelial cells in the imaginal disks. The dpp protein product predicted from the DNA sequence is similar to members of a family of growth factors that includes transforming growth factor beta (TGF-beta). We have produced polyclonal antibodies to a recombinant dpp protein made in bacteria and used a metallothionein promoter to express a dpp cDNA in Drosophila S2 cells. Similar to other proteins in the TGF-beta family, the dpp protein produced by the Drosophila cells was proteolytically cleaved, and both portions of the protein were secreted from the cells. The amino-terminal 47-kilodalton (kDa) peptide was found in the medium and in the proteins adhering to the plastic petri dish. The carboxy-terminal peptide, the region with sequence similarity to the active ligand portion of TGF-beta, was found extracellularly as a 30-kDa homodimer. Most of the 30-kDa homodimer was in the S2 cell protein adsorbed onto the surface of the plastic dish. The dpp protein could be released into solution by increased salt concentration and nonionic detergent. Under these conditions, the amino-terminal and carboxy-terminal portions of dpp were not associated in a stable complex.


1994 ◽  
Vol 14 (6) ◽  
pp. 4280-4285
Author(s):  
A Bhushan ◽  
H Y Lin ◽  
H F Lodish ◽  
C R Kintner

The type II receptors for the polypeptide growth factors transforming growth factor beta (TGF-beta) and activin belong to a new family of predicted serine/threonine protein kinases. In Xenopus embryos, the biological effects of activin and TGF-beta 1 are strikingly different; activin induces a full range of mesodermal cell types in the animal cap assay, while TGF-beta 1 has no effects, presumably because of the lack of functional TGF-beta receptors. In order to assess the biological activities of exogenously added TGF-beta 1, RNA encoding the TGF-beta type II receptor was introduced into Xenopus embryos. In animal caps from these embryos, TGF-beta 1 and activin show similar potencies for induction of mesoderm-specific mRNAs, and both elicit the same types of mesodermal tissues. In addition, the response of animal caps to TGF-beta 1, as well as to activin, is blocked by a dominant inhibitory ras mutant, p21(Asn-17)Ha-ras. These results indicate that the activin and TGF-beta type II receptors can couple to similar signalling pathways and that the biological specificities of these growth factors lie in their different ligand-binding domains and in different competences of the responding cells.


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