Effects Of TGF-beta Research Articles

Transforming growth factor (TGF)-β1-induced human endometrial stromal cell decidualization through extracellular signal-regulated kinase and Smad activation in vitro: peroxisome proliferator-activated receptor gamma acts as a negative regulator of TGF-β1

To investigate the effect of transforming growth factor (TGF)-beta1 on the extracellular signal-regulated kinase (ERK) and Smad pathway and the role of peroxisome proliferator-activated receptor (PPAR)-gamma in cultured human endometrial stromal cells. Experimental study. Infertility center of a tertiary university hospital. MATERIAL(S): Human endometrial tissues obtained by hysterectomy from patients with conditions other than endometrial diseases. Endometrial stromal cells were cultured under normal laboratory conditions. TGF-beta1, rosiglitazone (PPARgamma agonist), and PD98059 (ERK inhibitor) were added to endometrial stromal cell culture according to experimental purposes. Cell count, PRL expression, Smad and ERK phosphorylation, cyclooxygenase (COX)-2 expression, and prostaglandin E(2) (PGE(2)) release. TGF-beta1 inhibited cellular proliferation and induced the expressions of COX-2, PGE(2), and PRL of cultured human endometrial stromal cells. These effects may be mediated by Smad and ERK phosphorylation. Treatment with rosiglitazone, a PPARgamma agonist, reversed the TGF-beta1 effect by antagonizing the activation of ERK and Smad that was induced by TGF-beta1. PPARgamma plays a negative role by directly acting on Smad and ERK phosphorylation in human endometrial cell decidualization that is induced by TGF-beta1 in vitro.

GDNF prevents TGF-β-induced damage of the plasma membrane in cerebellar granule neurons by suppressing activation of p38-MAPK via the phosphatidylinositol 3-kinase pathway

Transforming growth factor-beta (TGF-beta) and glial-cell-line-derived neurotrophic factor (GDNF) have been shown to synergize in several paradigms of neuronal survival. We have previously shown that cerebellar granule neurons (CGN) degenerate in low potassium via ERK1/2 (extra-cellular-regulated kinase)-dependent plasma membrane (PM) damage and caspase-3-dependent DNA fragmentation. Here, we have investigated the putative synergistic function of GDNF and TGF-beta in CGN degeneration. GDNF alone prevents low-potassium-induced caspase-3 activation and DNA fragmentation but does not affect either low-potassium-induced ERK activation or PM damage. TGF-beta alone does not affect low-potassium-induced DNA fragmentation but potentiates low-potassium-induced PM damage. This effect of TGF-beta is independent of ERK1/2 activation but dependent on p38-MAPK (mitogen-activated protein kinase) activation. When co-applied with TGF-beta, GDNF paradoxically antagonizes TGF-beta-induced potentiation of PM damage by inhibiting TGF-beta-induced p38-MAPK activation. In addition, PI3K (phosphatidylinositol 3-kinase) inhibitors abolish the GDNF effect. This study thus demonstrates a differential mechanism of action of GDNF and TGF-beta on CGN degeneration. GDNF inhibits caspase-3-dependent DNA fragmentation but does not affect ERK-dependent PM damage. However, GDNF can attenuate TGF-beta-induced p38-MAPK-dependent PM damage via the PI3K pathway.

Effect of TGF-β1 on the expression of IL-12, IL-15, IL-18, IL-4 and IL-10 in heart transplantation rejection in rats

To investigate the effect of TGF-beta1 on the expressions of IL-12, IL-15, IL-18, IL-4 and IL-10 in heart transplantation rejection in rats, a model of rat cervical heterotopic heart transplantation was set up and the model rats were randomly divided into three groups: control group, transplant group and TGF-beta1 group. The mRNA expression levels of IL-12, IL-15, IL-18, IL-4 and IL-10 were determined by RT-PCR at the 5th day after the transplantation. The mRNA expression levels of IL-12, IL-15, IL-18 were increased obviously and those of IL-4, IL-10 were significantly decreased in the transplant group as compared with the control group (P<0.01). In the TGF-beta1 group, the mRNA expression levels of IL-12, IL-15, IL-18 were significantly decreased and those of IL-4, IL-10 were significantly increased as compared with the transplant group (P<0.01). The immunosuppressive effect of TGF-beta1 on heart transplantation rejection was related to its inhibition of the expressions of Th1-type cytokines (IL-12, IL-15, IL-18 etc) and its promotion of the expressions of Th2-type cytokines (IL-4, IL-10).

Endothelin is a downstream mediator of profibrotic responses to transforming growth factor β in human lung fibroblasts

Fibrosis is excessive scarring caused by the accumulation and contraction of extracellular matrix proteins and is a common end pathway in many chronic diseases, including scleroderma (systemic sclerosis [SSc]). Indeed, pulmonary fibrosis is a major cause of death in SSc. Transforming growth factor beta (TGFbeta) induces endothelin 1 (ET-1) in human lung fibroblasts by a Smad-independent, JNK-dependent mechanism. The goal of this study was to assess whether ET-1 is a downstream mediator of the profibrotic effects of TGFbeta in lung fibroblasts. We used a specific endothelin receptor antagonist to determine whether ET-1 is a downstream mediator of TGFbeta responses in lung fibroblasts, using microarray technology, real-time polymerase chain reaction, and Western blot analyses. The ability of TGFbeta to induce the expression of a cohort of profibrotic genes, including type I collagen, fibronectin, and CCN2, and to contract a collagen gel matrix, depends on ET-1. ET-1 contributes to the ability of TGFbeta to promote a profibrotic phenotype in human lung fibroblasts, consistent with the notion that endothelin receptor antagonism may be beneficial in controlling fibrogenic responses in lung fibroblasts.

TGFB1 promoter polymorphism C-509T and pathophysiology of asthma

TGF-beta1 can modulate airway inflammation and exaggerate airway remodeling. A polymorphism of a promoter region of TGFB1, C-509T, might be associated with the development of asthma, but its pathophysiologic relevance remains poorly understood. We investigated relations of the C-509T polymorphism to airflow obstruction, sputum eosinophilia, and airway wall thickening, as assessed by means of computed tomography, in 85 patients with stable asthma. The CC, CT, and TT genotypes were examined by means of PCR and restriction enzyme fragment length polymorphism. At a selected bronchus, 3 indices of airway wall thickness were measured with an automatic method. The CC, CT, and TT genotypes were found in 22, 46, and 17 patients, respectively. Serum TGF-beta1 levels were significantly associated with the polymorphism and were increased in the CT/TT genotypes. FEV(1) and sputum eosinophil percentages were also significantly associated with the polymorphism and were both decreased in the CT/TT genotypes. The polymorphism was unrelated to airway wall thickness. In addition to increased serum TGF-beta1 levels, the T allele of the C-509T polymorphism is related to increased airflow obstruction but attenuated eosinophilic inflammation. The former relation is not attributed to thickening of the central airway walls. The latter relation might reflect the anti-inflammatory effect of TGF-beta1. The C-509T polymorphism has a complex role in asthma pathophysiology, presumably because of the diverse functions of TGF-beta1 and its various interactions with cells and humoral factors in vivo.

Transforming growth factor-beta1 attenuates expression of both the progesterone receptor and Dickkopf in differentiated human endometrial stromal cells.

TGFbeta1 is thought to be intimately involved in cyclic tissue remodeling and inflammatory events associated with menstruation. Menstruation is initiated by progesterone withdrawal; however, the underlying mechanisms are not well understood. In the present study, we have tested the hypothesis that locally produced TGFbeta1 may influence expression of progesterone receptor (PR) or the Wnt antagonist Dickkopf-1 (DKK) with consequential impact on regulation of menstruation. Endometrial stromal cells (ESC) were isolated from endometrial biopsy samples collected from patients undergoing gynecological procedures for benign indications. Treatment of differentiated ESC with TGFbeta1 (10 ng/ml) significantly inhibited the expression of mRNAs encoding PR and DKK. TGFbeta1 also attenuated the protein expression of PR and secretion of DKK proteins in culture supernatants. Neutralization of endogenous TGFbeta1 signaling abolished the TGFbeta1-induced effects, significantly increased expression of PR, and increased DKK protein release levels to that of differentiated ESCs, confirming the specificity of the TGFbeta1 effect. Additionally, in vitro decidualization of ESCs significantly augmented DKK protein release. Moreover, although TGFbeta1 was capable of signaling via the Sma- and mothers against decapentaplegic (MAD)-related protein (SMAD) pathway, the inhibitory effect on DKK was SMAD independent. Conversely, the inhibitory effect of TGFbeta1 on PR was dependent on SMAD signal transduction. In conclusion, these results suggest that local TGFbeta1 signaling can potentiate progesterone withdrawal by suppressing expression of PR and may coordinate tissue remodeling associated with menstruation by inducing Wnt-signaling via inhibition of DKK, which we found to be up-regulated as a consequence of decidualization of ESCs.

Synergistic effect between EGF and TGF-β1 in inducing oncogenic properties of intestinal epithelial cells

Transforming growth factor (TGF)-beta1 has a biphasic effect on rat intestinal epithelial (RIE) cells. By itself, TGF-beta1 functions as a tumor suppressor by inhibiting the growth, migration and invasion of RIE cells. We show in this study that in conjunction with epidermal growth factor (EGF), TGF-beta1 helped to augment migration, invasion and anchorage-independent growth (AIG) compared to that by EGF alone. EGF plus TGF-beta1 induced a dramatic morphological change characteristic of epithelial-mesenchymal transition (EMT). The mechanism for this enhanced effect of TGF-beta1 and EGF on oncogenic properties was explored by analysis of EGF- and TGF-beta1-mediated signaling pathways and complementary DNA arrays. TGF-beta1 augmented EGF-mediated signaling of mitogen-activated protein kinase (MAPK) and AKT by enhancing and prolonging the activation of the former and prolonging the activation of the latter. Inhibition of MAPK, but not phosphoinositide-3 kinase (PI3K), abolished TGF-beta1 plus EGF-induced EMT and downregulation of E-cadherin at mRNA and protein levels. By contrast, cell migration and invasion were sensitive to inhibition of either MAPK or PI3 kinase. TGF-beta1 plus EGF-induced AIG was significantly more resistant to inhibition of PI3K and MAPK compared to that induced by EGF alone. EGF and TGF-beta1 synergistically induced the expression of a series of proteases including matrix metalloproteinase (MMP) 1 (collagenase), MMP3, MMP9, MMP10, MMP14 and cathepsin. Among them, the expression of MMP1, MMP3, MMP9 and MMP10 was MAPK dependent. Inhibition of the MMPs or cathepsin significantly blocked EGF plus TGF-beta1-induced invasion, but had no effect on colony formation. Phospholipase C (PLC) and Cox2 induced by EGF plus TGF-beta1 also played a significant role in invasion, whereas PLC was also important for colony formation. Our study reveals specific signaling functions and induction of genes differentially required for enhanced effect of EGF- and TGF-beta1-induced oncogenic properties, and helps to explain the tumor-promoting effect of TGF-beta1 in human cancer with elevated expression or activation of TGF-beta1 and receptor protein tyrosine kinases.

Context-dependent regulation of cutaneous immunological responses by TGF 1 and its role in skin carcinogenesis

Transforming growth factor beta1 (TGFbeta1) signaling plays a critical role in skin carcinogenesis. While most studies have focused on TGFbeta1 signaling and response in keratinocytes, it is now becoming clear that the interaction of keratinocyte-derived TGFbeta1 with cells of the immune system has an equally important role in tumor development. Tumors form within the context of innate and adaptive immune responses and studies in skin and skin carcinogenesis models have provided important insight into the impact of context-dependent pro-inflammatory and immunosuppressive actions of TGFbeta1 on tumor development. Indeed, the paradigm of TGFbeta1 duality is clearly evident in its ability to both promote and inhibit inflammatory responses. Recent studies have begun to shed new light on the molecular basis for these actions and to provide insight into how these may contribute to context-dependent effects of TGFbeta1 on carcinogenesis in the skin and other epithelial tissues.

Macrophage and TGF- β immunohistochemical expression in Jorge Lobo's disease

Jorge Lobo's disease, or lacaziosis, is a chronic deep mycosis that clinically manifests as solid, variable-sized nodular parakeloidal lesions. Few studies have characterized the in situ cellular and humoral immune response, especially the involvement of cytokines with immunosuppressive effects such as TGF-beta. The objective this paper was to analyze the expression of TGF-beta in cutaneous lesions in lacaziosis and investigate its importance in the etiopathogy of the disease. The results indicate that the abundance of collagen bands, together with weak immunolabeling for CD68 seen in macrophages, indicates a concomitant effect of TGF-beta inhibiting macrophages and inducing fibrosis, which is responsible for the keloid aspect frequently acquired by these lesions. Finally, the evolution of the infection supports the hypothesis that TGF-beta plays a fundamental role in the etiopathology of Lacazia loboi infection, either by inhibiting the cellular immune response mainly mediated by macrophages or by inducing fibrosis. Further studies are necessary to better characterize the phenotype of the inflammatory infiltrate as well as the participation of other cytokines and growth factors in the tissue response of the host in Jorge Lobo's disease.

Cyclooxygenase-2 overexpression abrogates the antiproliferative effects of TGF-β

The influence of cyclooxygenase-2 (COX-2) overexpression on the development of tumours has been well documented. The underlying mechanism however has still not been completely elucidated. An escape of proliferating cells from the regulatory influence of TGF-β for example in the intestine has been discussed as well as a preponderance or prolongation of growth factor stimulation. The experiments presented here demonstrated that COX-2 transfection of a TGF-β-sensitive cell line abrogates the growth inhibitory effects of TGF-β. However, analysis of the TGF-β/Smad-signalling pathway clearly revealed that COX-2 overexpression did not interfere with that. Neither TGF-receptor expression nor Smad phosphorylation and signal transfer into the nucleus were influenced by COX-2 overexpression. In addition, a TGF-β reporter assay revealed no difference between controls and COX-2-transfected cells. Thus, the proliferation inhibiting effects must have been well compensated by growth-inducing stimuli. Indications for this came from experiments showing an induction of TGF-α expression and secretion with a higher and prolonged stimulation of the ERK 1/2 (p42/44) pathway in COX-2 transfectants. This effect could have been triggered by direct prostaglandin receptor stimulation or changes in intracellular lipid mediators. An increase in PPAR signalling as proven by a reporter assay is indication for the latter. Therefore, inhibiting both COX-2 as well as the PPAR and TGF/EGF pathway could be effective in the inhibition of adenoma or even carcinoma development in the intestine.

Abstract 782: Fra2 Mediates Oxygen-induced TGFbeta-1 mRNA Expression In Adult Cardiac Fibroblasts: Significance In Myocardial Fibrosis Following Ischemia-reperfusion Injury

Background . Transforming growth factor beta-1 (TGFbeta-1) is a key cytokine implicated in the development of cardiac fibrosis following ischemia-reperfusion (IR) injury. The profibrotic effects of TGFbeta-1 are primarily attributable to the differentiation of cardiac fibroblasts (CF) to myofibroblasts. Previously, we have reported perceived hyperoxia (Circ Res 92:264 –71), sub-lethal reoxygenation shock during IR, induces differentiation of CF to myofibroblasts at the infarct site. The mechanisms underlying oxygen-sensitive induction of TGFbeta-1 mRNA remain to be characterized. Hypothesis . Fra2 mediates oxygen-induced TGFbeta-1 mRNA expression in adult cardiac fibroblasts. Methods. TGFbeta-1 mRNA expression in infarct tissue was investigated in an IR injury model. The left anterior descending coronary artery of mice was transiently occluded for 60 minutes followed by reperfusion to induce IR injury. Spatially resolved infarct and non-infarct tissues were collected at 0, 1, 3, 5, and 7 days post-IR using laser capture microdissection. TGFbeta-1 mRNA levels were measured using real-time PCR. To investigate the role of oxygen in the regulation of TGFbeta-1, we used our previously reported model of perceived hyperoxia where CF (from 5wks old mice) after isolation were cultured at 5%O 2 (physiological pO 2 ) followed by transferring them to 20%O 2 to induce hyperoxic insult. Results &amp; Conclusions. In vivo, a significant increase (p&lt;0.01; n=5) in TGFbeta-1 mRNA was observed at the infarct site already at day 1 post-IR. The levels continued to increase until day 7 post-IR. In vitro, exposure of CF to 20%O 2 hyperoxic insult induced TGFbeta-1 mRNA (p&lt;0.001; n=4) and protein (p&lt;0.01; n=4) expression. Using a TGFbeta-1 promoter-luciferase reporter and DNA binding assays, we collected first evidence that AP-1 and its component Fra2 as major mediators of oxygen-induced TGFbeta-1 expression. Exposure to 20%O 2 resulted in increased localization of Fra2 in nucleus. siRNA-dependent Fra-2 knock-down completely abrogated oxygen-induced TGFbeta1 expression. In conclusion, this study presents first evidence that Fra-2 is involved in inducible TGFbeta1 expression in CF. Fra2 was noted as being central in regulating oxygen-induced TGFbeta-1 expression.s

Preferential Induction of Transforming Growth Factor–β Production in Gastric Epithelial Cells and Monocytes byHelicobacter pyloriSoluble Proteins

The cytokines induced by Helicobacter pylori, as well as the intricate balance of proinflammatory and anti-inflammatory cytokines, are relevant to the outcomes of H. pylori infection. Transforming growth factor (TGF)-beta and interleukin (IL)-10 are 2 vital anti-inflammatory cytokines that regulate mucosal immunity in various inflammatory and infectious diseases. To elucidate whether host-bacteria interaction can influence TGF-beta and IL-10 production, we investigated the expression of TGF-beta and IL-10 in various mammalian cell lines preincubated with H. pylori and other enteric bacteria. The amount of TGF-beta protein, but not IL-10, was significantly increased after stimulation with H. pylori, but other enteric bacteria did not induce TGF- beta production. Different H. pylori strains isolated from patients with gastritis, peptic ulcer, gastric cancer and strains with cagA or vacA isogenic mutations showed similar effects on TGF-beta induction, indicating that this effect was a constitutional characteristic of H. pylori and independent of cagA and vacA status. The results imply the presence of a protein factor (termed "TGF-beta-inducing protein") that induces production of TGF-beta. In view of the multiple effects of TGF-beta , we conclude the TGF-beta-inducing protein of H. pylori might mediate the immune response and contribute to the pathogenesis of H. pylori infection.

Expression of TGF-beta 2 in human glioblastoma: a role in resistance to immune rejection?

Glioblastomas are among the most malignant tumours for which no curative treatment exists. A dysfunction of cellular immunity with decreased skin reactivity and lymphocyte blastogenesis has been described in patients with glioblastomas. In culture human glioblastoma cells release a factor termed glioblastoma-derived T cell suppressor factor (G-TsF) which inhibits the antigen-dependent growth of both helper and cytotoxic T cells. Purification and cloning indicated that G-TsF is a novel member of the TGF-beta family with a well-conserved mature sequence but less homology in the precursor segments. The factor was renamed TGF-beta 2. The two glioblastoma cell lines investigated expressed mRNAs for both G-TsF/TGF-beta 2 and TGF-beta 1 but only G-TsF/TGF-beta 2 protein was secreted. Neuroblastoma cells express only the mRNA for TGF-beta 1 but not the protein, nor the mRNA for G-TsF/TGF-beta 2. Recombinant G-TsF/TGF-beta 2 inhibits the generation of virus-specific cytotoxic T cells when injected into mice infected with lymphocytic choriomeningitis virus. Thus G-TsF/TGF-beta 2 might contribute to the impairment of tumour immune surveillance. Some T cell clones may escape the immunosuppressive effects of TGF-beta: ovalbumin-specific T helper cell lines that showed different degrees of susceptibility to TGF-beta contained clones which had lost receptor(s) for TGF-beta.

In vivo and in vitro effects of TGF-beta 1 on normal and neoplastic haemopoiesis.

TGF-beta 1 and TGF-beta 2 are equipotent selective inhibitors of murine and human haemopoiesis in vitro. Primitive haemopoietic cells such as the high proliferative potential progenitor cell and the colony-forming unit (CFU)-GEMM are directly inhibited by TGF-beta whereas the more differentiated CFU-G, CFU-M and CFU-E are not. Recombinant TGF-beta 1 administered intraperitoneally or intravenously to mice selectively inhibits haemopoietic colony formation in a time- and dose-dependent manner to the same extent as seen in vitro. The progenitors are reversibly prevented from entering the cell cycle. This inhibitory action of TGF-beta functions on at least two levels: (1) down-modulation of the cell surface expression of receptors for growth stimulatory molecules and (2) interference with the intracellular signalling pathways of these molecules. In addition, expression of TGF-beta receptors is regulated during cytokine stimulation of haemopoiesis. Neoplastic B lymphocytes can proliferate by escaping from a TGF-beta-mediated autocrine inhibitory loop. Activation signals (e.g. phorbol esters) inhibit tumour cell growth by stimulating active TGF-beta production and inducing cell surface expression of TGF-beta receptors. These results indicate that TGF-beta may be useful as a bone marrow protective and/or an antitumour agent.

TGF-β Suppresses EGF-Induced MAPK Signaling and Proliferation in Asthmatic Epithelial Cells

Epithelial damage is an important pathophysiologic feature of asthma. Bronchial epithelium damage results in release of growth factors such as transforming growth factor (TGF)-beta(1) that may affect epithelial cell proliferation. The objective of our study is to evaluate the importance of TGF-beta(1) in regulating epithelial cell repair in asthma. We evaluated the effect of TGF-beta(1) on epidermal growth factor (EGF)-induced proliferation and downstream signaling in epithelial cells obtained from subjects with asthma compared with cells from healthy subjects. Cell proliferation was evaluated by bromodeoxyuridine incorporation. EGF receptor (EGFR), mitogen-activated protein kinase, TGF-beta receptors, Smads, Smad anchor for receptor activation (SARA), and cyclin-dependant kinase inhibitors were evaluated by Western blot. TGF-beta(1) and receptor expression were measured by RT-PCR and by enzyme-linked immunosorbent assay. Proliferation of epithelial cells at baseline and after EGF stimulation was significantly reduced in cells derived from subjects with asthma compared with cells obtained from healthy control subjects. EGF-induced ERK1/2 phosphorylation was reduced in epithelial cells from subjects with asthma compared with cells from healthy control subjects. This was paralleled with a reduced EGFR phosphorylation. Addition of TGF-beta(1) significantly decreased EGF-induced cell proliferation. TGF-beta(1) production was higher in asthmatic epithelial cells compared with normal cells. This was supported by a high expression of pSmad 3 and SARA in cells derived from individuals with asthma compared with normal subjects. Cycline-dependent kinase inhibitors were highly expressed in asthmatic compared with normal cells. Inhibition of TGF-beta(1) signaling in asthmatic epithelial cells restored EGFR, ERK1/2 phosphorylation, and cell proliferation induced by EGF. Our results suggest that TGF-beta restrains EGFR phosphorylation and downstream signaling in bronchial epithelial cells.

SMAD3 inhibits SF-1-dependent activation of the CYP17 promoter in H295R cells

Cytochrome P450c17, encoded by the CYP17 gene, is a component of 17alpha-hydroxylase/17,20 lyase which catalyses 17alpha-hydroxylation of pregnenolone or progesterone, required for glucocorticosteroid and androgen synthesis. It has been reported that transforming growth factor beta (TGF-beta) decreases both basal and cAMP-stimulated levels of CYP17 mRNA, but the mechanism of TGF-beta action on CYP17 expression remains unknown. We investigated an inhibitory effect of TGF-beta on CYP17 expression in H295R cells using constructs containing the CYP17 promoter region fused with the luciferase gene. In the H295R cells, TGF-beta decreased endogenous SF-1 level and inhibited activity of the 300 bp fragment of CYP17 promoter, which was stimulated by coexpression of SF-1. Overexpression of SMAD3 caused an inhibition of SF-1-stimulated CYP17 promoter activity, whereas overexpression of SMAD7 was ineffective. In conclusion, our results suggest that the inhibitory action of TGF-beta on CYP17 transcription involve at least two mechanisms: SMAD3 dependent inactivation of CYP17 promoter activity and repression of SF-1 expression.

Modulation of tumor induction and progression of oncogenic K-ras-positive tumors in the presence of TGF- 1 haploinsufficiency

Oncogenic K-ras is one of the most common genetic alterations in human lung adenocarcinomas. In addition, inactivation of clusters of tumor suppressor genes is required to bring about classical characteristics of cancer including angiogenesis as a prelude to invasion and metastasis. Transforming growth factor-beta (TGF-beta) 1 is a tumor suppressor gene that is implicated in lung cancer progression. Although in vitro studies have shown that TGF-beta1 and Ras pathways cooperate during tumorigenesis, the biology of interaction of TGF-beta1 and Ras has not been studied in in vivo tumorigenesis. We hypothesized that inactivation of TGF-beta1 in addition to oncogeneic activation of K-ras would lead to early initiation and faster progression to lung adenocarcinoma and invasion and metastasis. Heterozygous (HT) TGF-beta1 mice were mated with latent activatable (LA) mutated K-ras mice to generate TGF-beta1(+/+), K-ras LA (wild-type (WT)/LA) and TGF-beta1(+/-), K-ras LA (HT/LA) mice. Both HT/LA and WT/LA mice developed spontaneous lung tumors, but HT/LA mice progressed to adenocarcinomas significantly earlier compared with WT/LA mice. In addition, WT/LA adenocarcinomas had significantly higher angiogenic activity compared with HT/LA adenocarcinomas. Thus, while oncogenic K-ras mutation and insensitivity to the growth regulatory effects of TGF-beta1 is essential for initiation and progression of mouse lung tumors to adenocarcinoma, a full gene dosage of TGF-beta1 is required for tumor-induced angiogenesis and invasive potential. This study identifies a number of genes not previously associated with lung cancer that are involved in tumor induction and progression. In addition, we provide evidence that progression to invasive angiogenic lesions requires TGF-beta1 responsiveness in addition to Ras mutation.

CD4+CD25+ T Regulatory Cells and TGF-&amp;#946; in Mucosal Immune System: The Good and the Bad

Three major mucosal systems exist in the body, the oral-gastrointestinal, the respiratory and the genitourinary systems. In particular, the gastrointestinal (GI) tract contains the largest mucosal surface in the body and is the major port of entry for foreign antigens. Therefore, the gut immune system has to differentiate to tolerate dietary antigens and expel infectious and harmful pathogens. During the complex but well-orchestrated immune responses in the mucosal system, T cells play a pivotal role in both immunity and tolerance. Of many T cell subpopulations, CD4(+)CD25(+) T regulatory cells (Tregs) are instrumental in regulation of immune responses in mucosea. Among the multitude of cytokines and factors that are produced in the gut, Transforming Growth Factor-beta (TGF-beta) is probably the most important one in influencing mucosal T cell responses. The interaction and mutual regulation between TGF-beta and CD4(+)CD25(+) Tregs may be the key in maintaining the balance between T cell immunity and tolerance in mucosal system. In this article, we attempt to discuss both beneficial and detrimental effects of TGF-beta and Tregs on oral tolerance, mucosal inflammation and autoimmunity, colon cancer and HIV infection in the gut.

Transforming growth factor-beta in the brain enhances fat oxidation via noradrenergic neurons in the ventromedial and paraventricular hypothalamic nucleus

We have previously reported that intracisternal administration of TGF-beta induces an increase in fat oxidation and that intracisternal administration of anti-TGF-beta antibody partially inhibits an increase in fat oxidation during treadmill running in rats. These results indicate a regulatory role of that TGF-beta in the brain on fat oxidation during exercise. However, it is not clear how TGF-beta in the brain enhance fat oxidation. We hypothesized that TGF-beta in the brain elicits its regulatory effects on fat oxidation via hypothalamic noradrenergic neurons, because some reports have demonstrated the important role of hypothalamic noradrenergic neurons in the regulation of fat oxidation during and after exercise. To examine this hypothesis, we measured the extracellular noradrenaline (NA) levels in the paraventricular hypothalamic nucleus (PVH), ventromedial hypothalamic nucleus (VMH) and lateral hypothalamic area, which are especially important in the regulation of energy metabolism, after intracisternal administration of TGF-beta by using an in vivo brain microdialysis. Microdialysis study revealed that intracisternal administration of TGF-beta3 caused increases in the NA levels in the PVH and VMH. Then, we investigated the impact of impairment of noradrenergic neurons in the PVH and VMH by neurotoxin 6-hydroxydopamine microinjection (NA-lesion) on the action of intracisternal administration of TGF-beta. The NA lesion completely abolished the regulatory effect of TGF-beta on fat oxidation. These results suggest that TGF-beta in the brain enhances fat oxidation via noradrenergic neurons in the PVH and VMH.

Transforming Growth Factor-β and Wnt Signals Regulate Chondrocyte Differentiation through Twist1 in a Stage-Specific Manner

We investigated the molecular mechanisms underlying the transition between immature and mature chondrocytes downstream of TGF-beta and canonical Wnt signals. We used two developmentally distinct chondrocyte models isolated from the caudal portion of embryonic chick sternum or chick growth plates. Lower sternal chondrocytes exhibited immature phenotypic features, whereas growth plate-extracted cells displayed a hypertrophic phenotype. TGF-beta significantly induced beta-catenin in immature chondrocytes, whereas it repressed it in mature chondrocytes. TGF-beta further enhanced canonical Wnt-mediated transactivation of the Topflash reporter expression in lower sternal chondrocytes. However, it inhibited Topflash activity in a time-dependent manner in growth plate chondrocytes. Our immunoprecipitation experiments showed that TGF-beta induced Sma- and Mad-related protein 3 interaction with T-cell factor 4 in immature chondrocytes, whereas it inhibited this interaction in mature chondrocytes. Similar results were observed by chromatin immunoprecipitation showing that TGF-beta differentially shifts T-cell factor 4 occupancy on the Runx2 promoter in lower sternal chondrocytes vs. growth plate chondrocytes. To further determine the molecular switch between immature and hypertrophic chondrocytes, we assessed the expression and regulation of Twist1 and Runx2 in both cell models upon treatment with TGF-beta and Wnt3a. We show that Runx2 and Twist1 are differentially regulated during chondrocyte maturation. Furthermore, whereas TGF-beta induced Twist1 in mature chondrocytes, it inhibited Runx2 expression in these cells. Opposite effects were observed upon Wnt3a treatment, which predominates over TGF-beta effects on these cells. Finally, overexpression of chick Twist1 in mature chondrocytes dramatically inhibited their hypertrophy. Together, our findings show that Twist1 may be an important regulator of chondrocyte progression toward terminal maturation in response to TGF-beta and canonical Wnt signaling.