Transforming growth factor-β1 production in porcine thyroid follicular cells: regulation by intrathyroidal organic iodine

1992 ◽  
Vol 9 (3) ◽  
pp. 197-205 ◽  
Author(s):  
A. J. Cowin ◽  
J. R. E. Davis ◽  
S. P. Bidey

ABSTRACT The present studies have demonstrated the production of transforming growth factor-β1 (TGF-β1) by porcine thyroid follicular cells (TFCs) maintained in vitro as subconfluent monolayers, and have confirmed a stimulatory effect of iodide on thyroidal TGF-β1 mRNA and peptide release. RNA extracted from TFCs maintained in the absence of iodide contained a 2·5 kb transcript which hybridized specifically with a cDNA probe for human TGF-β1, and which showed an approximate doubling in intensity in cells exposed to 10 μmol NaI/l. In the presence of the anti-thyroid thionamide drug methimazole (MMI; 1 mmol/l), the action of iodide on TGF-β1 mRNA was attenuated, although MMI alone had no effect on the control level of TGF-β1 mRNA. The TGF-β1 peptide content of TFC-conditioned media (TFC-CM) was assessed using the fetal mink lung cell line Mv1 Lu, in which activated TGF-β1 specifically suppresses trichloroacetic acid-precipitable [methyl-3H]thymidine incorporation. Newly conditioned TFC-CM stimulated [methyl-3H]thymidine incorporation into Mv1Lu cells, but after heat treatment to inactivate growth stimulators and activate the latent TGF-β1 component this medium inhibited [methyl-3H]thymidine incorporation. This inhibitory effect was prevented by immunoadsorption of TFC-CM with a TGF-β1-neutralizing antiserum, confirming the specificity of the inhibitory response. The inhibitory activity of TFC-CM was increased when the TFCs were preincubated with 10 μmol NaI/l, and lost when TFCs were exposed to MMI. In conclusion, TFCs produce TGF-β1 mRNA and TGF-β1 peptide, which are both increased by iodide treatment in vitro. The anti-thyroid effects of MMI may, at least in part, be mediated by a decrease in TFC-derived TGF-β1 production.

1996 ◽  
Vol 148 (1) ◽  
pp. 87-94 ◽  
Author(s):  
A J Cowin ◽  
E L Heaton ◽  
S H Cheshire ◽  
S P Bidey

Abstract The present study has investigated an involvement of autocrine transforming growth factor-β1 (TGF-β1) in regulating the proliferative response of porcine thyroid follicular cells (TFCs) to epidermal growth factor (EGF) and TSH. Primary monolayer TFC cultures exposed to EGF over the range 0–0·4 nmol/l showed a dose-dependent increase in [methyl-3H]thymidine incorporation, whereas higher EGF doses were associated with a reduction in the level of [methyl-3 H]thymidine incorporation. TGF-β immunoneutralisation had little effect on the stimulatory action of low EGF doses, but led to an increase in [methyl-3H]thymidine incorporation at higher EGF levels. In TFC cultures exposed to TSH, the level of [methyl-3H]thymidine incorporation attained at a dose of 1 U TSH/1 was enhanced in the presence of TGF-β1 antiserum, although the similar stimulatory effect of 8-bromo cAMP was unaffected. Treatment of TFCs with phorbol 12-myristate 13-acetate (8 nmol/l) to activate protein kinase C (PKC) led to an enhanced incorporation of [methyl-3H]thymidine which was increased further after neutralisation of endogenous TGF-β1. While confirming, therefore, a role for autocrine TGF-β1 in maintaining control of TFC DNA synthesis in vitro, these findings provide evidence that an increase in the availability of autocrine TGF-β1 effected by EGF and TSH may play an instrumental role in limiting the cellular hyperplasia induced by these factors within the thyroid follicular microenvironment. Moreover, the present data also suggest that the availability of active autocrine TGF-β1 to TFCs under such conditions may be dependent upon a PKC-mediated mechanism. Journal of Endocrinology (1996) 148, 87–94


1995 ◽  
Vol 144 (1) ◽  
pp. 67-73 ◽  
Author(s):  
A J Cowin ◽  
S P Bidey

Abstract The release of latent transforming growth factor-β1 (TGFβ1), and conversion to the biologically active peptide, has been investigated in porcine thyroid follicular cells maintained in primary monolayer culture. Analysis by radioreceptor assay of medium conditioned for 72 h by subconfluent thyroid monolayers showed that a high proportion of the expressed TGF-β1 peptide was in the active form. Medium conditioned by iodide (10 aμmol/l)treated follicular cells contained higher levels of both active and total TGF-β1 than were present in medium conditioned by untreated cells. Exposure of cells to iodide also led to a marked decrease in [methyl-3H]thymidine incorporation that was relieved by immunoadsorption with a neutralizing antiserum against the active form of TGFβ1. Inclusion of a low dose (80 units/l) of porcine plasmin led to a small increase in incorporation of [methyl3H]thymidine, while higher doses of plasmin (1250–5000 units/l) or plasminogen (100 mg/l) significantly reduced [methyl-3H]thymidine incorporation. This inhibition was effectively reversed by immunoadsorption of TGF-β1 from the medium during the test incubations. The study therefore provides direct evidence for a stimulatory role of thyroidal iodide in enhancing the release of latent TGF-β1 peptide, and suggests that in normal thyroid follicular cells, as in other TGF-β1 producing epithelia, post-secretory processing to the biologically active molecule occurs through an endogenous cellular mechanism. It appears likely that plasmin, generated locally within the thyroid follicular microenvironment, may play a fundamental role in effecting this conversion. Journal of Endocrinology (1995) 144, 67–73


1994 ◽  
Vol 141 (1) ◽  
pp. 183-190 ◽  
Author(s):  
A J Cowin ◽  
S P Bidey

Abstract The present study has investigated the relative levels and interconversion of latent and active forms of transforming growth factor-β1 (TGF-β1) in human thyroid follicular cell cultures derived from sporadic non-toxic goitres. Northern blotting of RNA extracted from 72-h cultures revealed a 2·5 kb mRNA transcript hybridizing with a cDNA probe for latent TGF-β1, the intensity of which was doubled in cells exposed to Nal (10 μmol/l). Radioreceptor assay of follicular cell-conditioned medium for TGF-β1 content confirmed a similar enhancing effect of iodide. The endogenous active component of TGF-β1 present in conditioned medium represented only a minor fraction of the total TGF-β1 content, this fraction was not enhanced by exposure of follicular cells to iodide. The low level of endogenous active TGF-β1 in medium conditioned by either control or iodide-treated cells was confirmed by immunoadsorption with a precipitating antiserum against active TGF-β1, when such cells failed to show a reversal of the iodide-induced decrease in [methyl-3H]thymidine incorporation into trichloroacetic acid-precipitable material. In contrast to the inhibitory effect of iodide on de novo DNA synthesis, which appeared not to reflect an increase in active TGF-β1, the inhibitory effects of plasminogen (100 mg/l) or plasmin (2000 U/l) on [methyl-3H]thymidine incorporation into thyroid cells were reversible by TGF-β1 immunoadsorption. This provides evidence that the plasmin-mediated inhibition of DNA synthesis in thyroid follicular cells may be attributed to the growth-regulating action of an increased level of activated TGF-β1. The findings of this study therefore provide evidence that (i) human thyroid follicular cells are potentially capable of activating locally derived latent TGF-β1, (ii) an increase in thyroidal TGF-β1 mRNA and latent TGF-β1 peptide availability, following exposure of cells to iodide, is not accompanied by a corresponding increase in active TGF-β1, and (iii) within the thyroid gland, as in other epithelial tissues, activation of endogenous TGF-β1 may be dependent upon the proteolytic actions of plasmin. Journal of Endocrinology (1994) 141, 183–190


1991 ◽  
Vol 130 (1) ◽  
pp. 3-9 ◽  
Author(s):  
H. M. Beere ◽  
J. Soden ◽  
S. Tomlinson ◽  
S. P. Bidey

ABSTRACT The regulation of thyroid follicular cell growth in vitro involves autocrine or paracrine actions of insulin-like growth factor-I (IGF-I), which are partially suppressed by transforming growth factor-β (TGF-β). Using subconfluent monolayers of porcine thyroid follicular cells, the aims of this study were to establish whether the actions of TGF-β involve changes in the synthesis of, or response to, IGF-I. We also investigated the extent to which inhibitory actions of iodide on IGF-I-dependent proliferation of thyroid follicular cells may be attributable to the production of TGF-β by follicular cells, as opposed to iodide-mediated autoregulation events. Exposure of porcine thyroid follicular cells in subconfluent monolayer culture to TGF-β over a 7-day period reduced both IGF-I release and the incorporation of [met hyl-3H]thymidine into trichloroacetic acidprecipitable cellular material, while preincubation of cells with NaI (0 ·1 mmol/l) for 24 h prior to the addition of TSH reduced the stimulatory effect of the latter on IGF-I release over the following 7 days. Preincubation of cells with iodide also reduced basal (i.e. autonomous) [methyl-3H]thymidine incorporation. This effect was partially reversed when, following initial exposure to follicular cells, iodide-containing preincubation medium was immunoadsorbed with a neutralizing TGF-β antiserum, and subsequently readded to the cells. Furthermore, similar immunoadsorption of iodide-free preincubation medium resulted in an enhancement of the control level of [methyl-3H]thymidine incorporation when the treated medium was returned to the original cultures. The results of this study are consistent with the hypothesis that IGF-I and TGF-β are both produced by subconfluent thyroid follicular cells in vitro, and that the inhibitory action of TGF-β on follicular cell growth may involve a decrease in the thyroidal production of IGF-I. While the attenuating action of iodide on follicular cell proliferation may, in part, reflect an increased autocrine production of TGF-β, and a reduction by TGF-β of the growth response to IGF-I, these studies also provide evidence that the intrathyroidal actions of TGF-β include an attenuation of IGF-I biosynthesis. Journal of Endocrinology (1991) 130, 3–9


2001 ◽  
Vol 21 (21) ◽  
pp. 7218-7230 ◽  
Author(s):  
Francesc Viñals ◽  
Jacques Pouysségur

ABSTRACT Mouse capillary endothelial cells (1G11 cell line) embedded in type I collagen gels undergo in vitro angiogenesis. Cells rapidly reorganize and form capillary-like structures when stimulated with serum. Transforming growth factor β1 (TGF-β1) alone can substitute for serum and induce cell survival and tubular network formation. This TGF-β1-mediated angiogenic activity depends on phosphatidylinositol 3-kinase (PI3K) and p42/p44 mitogen-activated protein kinase (MAPK) signaling. We showed that specific inhibitors of either pathway (wortmannin, LY-294002, and PD-98059) all suppressed TGF-β1-induced angiogenesis mainly by compromising cell survival. We established that TGF-β1 stimulated the expression of TGF-α mRNA and protein, the tyrosine phosphorylation of a 170-kDa membrane protein representing the epidermal growth factor (EGF) receptor, and the delayed activation of PI3K/Akt and p42/p44 MAPK. Moreover, we showed that all these TGF-β1-mediated signaling events, including tubular network formation, were suppressed by incubating TGF-β1-stimulated endothelial cells with a soluble form of an EGF receptor (ErbB-1) or tyrphostin AG1478, a specific blocker of EGF receptor tyrosine kinase. Finally, addition of TGF-α alone poorly stimulated angiogenesis; however, by reducing cell death, it strongly potentiated the action of TGF-β1. We therefore propose that TGF-β1 promotes angiogenesis at least in part via the autocrine secretion of TGF-α, a cell survival growth factor, activating PI3K/Akt and p42/p44 MAPK.


EP Europace ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1590-1599
Author(s):  
Maximilian Funken ◽  
Tobias Bruegmann ◽  
Philipp Sasse

Abstract Aims Besides providing mechanical stability, fibroblasts in the heart could modulate the electrical properties of cardiomyocytes. Here, we aim to develop a three-dimensional hetero-cellular model to analyse the electric interaction between fibroblasts and human cardiomyocytes in vitro using selective optogenetic de- or hyperpolarization of fibroblasts. Methods and results NIH3T3 cell lines expressing the light-sensitive ion channel Channelrhodopsin2 or the light-induced proton pump Archaerhodopsin were generated for optogenetic depolarization or hyperpolarization, respectively, and characterized by patch clamp. Cardiac bodies consisting of 50% fibroblasts and 50% human pluripotent stem cell-derived cardiomyocytes were analysed by video microscopy and membrane potential was measured with sharp electrodes. Myofibroblast activation in cardiac bodies was enhanced by transforming growth factor-β1 (TGF-β1)-stimulation. Connexin-43 expression was analysed by qPCR and fluorescence recovery after photobleaching. Illumination of Channelrhodopsin2 or Archaerhodopsin expressing fibroblasts induced inward currents and depolarization or outward currents and hyperpolarization. Transforming growth factor-β1-stimulation elevated connexin-43 expression and increased cell–cell coupling between fibroblasts as well as increased basal beating frequency and cardiomyocyte resting membrane potential in cardiac bodies. Illumination of cardiac bodies generated with Channelrhodopsin2 fibroblasts accelerated spontaneous beating, especially after TGF-β1-stimulation. Illumination of cardiac bodies prepared with Archaerhodopsin expressing fibroblasts led to hyperpolarization of cardiomyocytes and complete block of spontaneous beating after TGF-β1-stimulation. Effects of light were significantly smaller without TGF-β1-stimulation. Conclusion Transforming growth factor-β1-stimulation leads to increased hetero-cellular coupling and optogenetic hyperpolarization of fibroblasts reduces TGF-β1 induced effects on cardiomyocyte spontaneous activity. Optogenetic membrane potential manipulation selectively in fibroblasts in a new hetero-cellular cardiac body model allows direct quantification of fibroblast–cardiomyocyte coupling in vitro.


Marine Drugs ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 65 ◽  
Author(s):  
Agata Zykwinska ◽  
Mélanie Marquis ◽  
Mathilde Godin ◽  
Laëtitia Marchand ◽  
Corinne Sinquin ◽  
...  

Articular cartilage is an avascular, non-innervated connective tissue with limited ability to regenerate. Articular degenerative processes arising from trauma, inflammation or due to aging are thus irreversible and may induce the loss of the joint function. To repair cartilaginous defects, tissue engineering approaches are under intense development. Association of cells and signalling proteins, such as growth factors, with biocompatible hydrogel matrix may lead to the regeneration of the healthy tissue. One current strategy to enhance both growth factor bioactivity and bioavailability is based on the delivery of these signalling proteins in microcarriers. In this context, the aim of the present study was to develop microcarriers by encapsulating Transforming Growth Factor-β1 (TGF-β1) into microparticles based on marine exopolysaccharide (EPS), namely GY785 EPS, for further applications in cartilage engineering. Using a capillary microfluidic approach, two microcarriers were prepared. The growth factor was either encapsulated directly within the microparticles based on slightly sulphated derivative or complexed firstly with the highly sulphated derivative before being incorporated within the microparticles. TGF-β1 release, studied under in vitro model conditions, revealed that the majority of the growth factor was retained inside the microparticles. Bioactivity of released TGF-β1 was particularly enhanced in the presence of highly sulphated derivative. It comes out from this study that GY785 EPS based microcarriers may constitute TGF-β1 reservoirs spatially retaining the growth factor for a variety of tissue engineering applications and in particular cartilage regeneration, where the growth factor needs to remain in the target location long enough to induce robust regenerative responses.


1998 ◽  
Vol 530 ◽  
Author(s):  
Y. Tabata ◽  
M. Yamamoto ◽  
Y. Ikada

AbstractA biodegradable hydrogel was prepared by glutaraldehyde crosslinking of acidic gelatin with an isoelectric point (IEP) of 5.0 as a carrier to release basic growth factors on the basis of polyion complexation. Basic fibroblast growth factor (bFGF), transforming growth factor β1 (TGF-β1), and bone morphogenetic protein-2 (BMP-2) were sorbed from their aqueous solution into the dried gelatin hydrogels to prepare respective growth factor-incorporating hydrogels. Under an in vitro non-degradation condition, approximately 20 % of incorporated bFGF and TGF-β1 was released from the hydrogels within initial 40 min, followed by no further release, whereas a large initial release of BMP-2 was observed. After subcutaneous implantation of the gelatin hydrogels incorporating 125I-labeled growth factor in the mouse back, the remaining radioactivity was measured to estimate the in vivo release profile of growth factors. Incorporation into gelatin hydrogels enabled bFGF and TGF-β1 to retain in the body for about 15 days and the retention period well correlated with that of the gelatin hydrogel. Taken together, it is likely that the growth factors ionically complexed with acidic gelatin were released in vivo as a result of hydrogel biodegradation. On the contrary, basic BMP-2 did not ionically interact with acidic gelatin, resulting in no sustained released by the present biodegradable carrier system.


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