Effects of transforming growth factor β, tumor necrosis factor α and interferon γ on pancreatic islet β-cell responsiveness to transforming growth factor α

The insulin-producing pancreatic islet -cell, characterized by low proliferative potential, is normally not responsive to the polypeptide epidermal growth factor (EGF) or its homolog transforming growth factor (TGF-). Since EGF receptors in other tissues can be up-regulated by other growth factors and by cytokines, we have in this paper investigated whether such a -cell responsiveness to TGF-, or EGF, can be conferred by co-culture with interferon (IFN-), tumor necrosis factor (TNF-) or transforming growth factor (TGF-) in various combinations. To this end, fetal rat pancreatic islets enriched in -cells were isolated and cultured for 3 days with or without 200 pM or 20 nM TGF-. It was found that neither of these TGF- concentrations affected -cell mitogenesis, insulin content or insulin secretion. However, IFN- (1000 U/ml) evoked a modest stimulation of -cell replication, while suppressing insulin secretion and leaving the islet insulin content unaltered. TNF- (1000 U/ml), on the other hand, affected none of these parameters either alone or in any combination with TGF- or IFN-. However, when TNF- or IFN-, either alone or in combination, were combined with the cytokine interleukin-1, this resulted in islet disintegration, whereas the latter cytokine alone did not exert any gross necrotic changes evident by light microscopy. TGF- (500 pM) stimulated insulin secretion but did not influence islet insulin content or -cell mitogenesis either alone or in combination with TGF- (200 pM or 20 nM). In no instance could any mitogenic or secretory response to low or high concentrations of TGF- be conferred by IFN-, TNF- or TGF- whether used alone or in combinations. Hence, responsiveness to TGF- or EGF in the -cell obviously cannot be achieved by any of these peptides.Abbreviations EGF epidermal growth factor - IFN- interferon - TGF- transforming growth factor - TGF- transforming growth factor - TNF- tumor necrosis factor      

Immunohistochemical localization of transforming growth factor β1 and β2 in mouse testes during postnatal development

We examined age-related changes in the expression of transforming growth factor-β(1) (TGF-β(1)) and transforming growth factor-β(2) in mouse testes. The mice were assigned to three age groups: 35, 50, and 75 days old. Paraffin embedded testis sections were processed for the standard streptavidin biotin peroxidase complex immunohistochemistry method. TGF-β(1) expression increased in aging round spermatids over the time studied. There was no expression in 35-day-old Leydig cells, whereas strong expression of TGF-β(1) was observed in 50-day-old Leydig cells. Expression decreased in 75-day-old Leydig cells. TGF-β(2) expression was weak in 35- and 50-day-old mouse spermatids, but expression was greater in 75-day-old elongated spermatids. In Leydig cells, TGF-β(2) expression was strong in both 35- and 50-day-old mice, whereas the expression of TGF-β(2) was less in 75-day-old Leydig cells. Our results suggest that TGF-β(1) and TGF-β(2) may play significant roles in testicular functions and germ cell development in mice.     

Plasma transforming growth factor β1 as a biomarker of psoriasis activity and treatment efficacy

Transforming growth factor-β₁ (TGFβ₁) is thought to be an inhibitor of the keratinocyte hyperproliferation associated with psoriasis. The aim of this study was to evaluate plasma TGFβ₁ and TGFβ₂ concentrations in psoriatic patients as possible indicators of treatment efficacy. TGFβ concentrations were measured in the plasma of 26 patients with psoriasis using an enzyme immunoassay and analysed with respect to the psoriasis area and severity index (PASI) before and after treatment with salicylic acid and/or sulphur followed by dithranol ointment. Baseline plasma concentrations of both TGFβ₁ and TGFβ₂ (20.3±2.2 ng ml^?1 and 0.14±0.02 ng ml^?1, respectively) did not differ significantly from control values (18.3±1.6 ng ml^?1 and 0.14±0.03 ng ml^?1, respectively). However, a significant positive correlation (r=0.69) between the baseline PASI and TGFβ₁, but not TGFβ₂, values was demonstrated. The pretreatment TGFβ₁ concentration in patients with a PASI ≥15 (26.6±3.2 ng ml^?1) was significantly higher than control values. There were no significant elevation of pretreatment TGFβ₁ concentrations in patients with a PASI<15, or with respect to TGFβ₂ in both groups. Treatment caused a significant decrease in TGFβ₁, but only in patients with a PASI≥15. Patients with baseline TGFβ₁ concentrations exceeding the mean of the control group had a PASI value that was significantly higher than that of patients with a TGFβ₁ concentration below the mean of the controls. These results confirmed an association between plasma TGFβ₁ concentration and psoriasis severity, and demonstrated its normalization during treatment. Measurement of TGFβ₁ in plasma should be considered as a possible biomarker of psoriasis activity during its management.     

Genetic variance of transforming growth factor β2 gene in conotruncal heart defects

Objective: The aim of this study was to evaluate the association between two haplotype-tag single nucleotide polymorphisms (SNPs) (rs6658835 and rs10495098) of TGF-β2 and conotruncal heart defects (CTDs).

Methods: Two polymorphisms of TGF-β2 gene were genotyped by polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) from 259 CTDs patients and 310 control subjects.

Results: The association between SNP rs6658835 in TGF-β2 and CTDs has been found. The frequency of G allele in CTDs patients was significantly higher than that in control subjects (52.7% versus 40.3%, p?<?0.001, OR =1.649).

Conclusion: TGF-β2 gene polymorphisms may serve as a novel genetic marker for the risk of CTDs.     

Thrombospondin-4 critically controls transforming growth factor β1 induced hypertrophic scar formation

Transforming growth factor β (TGF-β) is a growth factor presenting important functions during tissue remodeling and hypertrophic scar (HS) formation. However, the underlying molecular mechanisms are largely unknown. In this study, we identified thrombospondin-4 (TSP-4) as a TGF-β1 target that essentially mediates TGF-β1-induced scar formation both in vitro and in vivo. The expression of TSP-4 was compared on both mRNA and protein levels between hypertrophic scar fibroblasts (HSFs) and normal skin fibroblast (NFs) in response to TGF-β1 treatment. Two signaling molecules, Smad3 and p38, were assessed for their importance in regulating TGF-β1-mediated TSP-4 expression. The significance of TSP-4 in controlling TGF-β1-induced proliferation, invasion, migration, and fibrosis in HSFs was analyzed by knocking down endogenous TSP-4 using small hairpin RNA (shRNA) (TSP-4 shRNA). Finally, a skin HS model was established in rats and the scar formation was compared between rats treated with vehicle (saline), TGF-β1, and TGF-β1 + TSP-4 shRNA. The TSP-4 level was significantly higher in HSFs than in NFs and TGF-β1 more potently boosted TSP-4 expression in the former than in the latter. Both Smad3 and p38 essentially mediated TGF-β1-induced TSP-4 expression. TSP-4 shRNA significantly suppressed TGF-β1-stimulated proliferation, invasion, migration, or fibrosis of HSFs in vitro and drastically improved wound healing in vivo. TGF-β1, by activating both Smad3 and p38, induces TSP-4, which in turn not only presents a positive feedback regulation on the activation of Smad3 and p38, but also essentially mediates TGF-β1-induced HS formation. Targeting TSP-4 thus may benefit HS treatment.     

Vitamin D inhibition of pro-fibrotic effects of transforming growth factor β1 in lung fibroblasts and epithelial cells

The mechanisms that control fibroproliferation and matrix deposition in lung fibrosis remain unclear. We speculate that vitamin D deficiency may contribute to pulmonary fibrosis since vitamin D deficiency has been implicated in several diseases. First, we confirmed the presence of vitamin D receptors (VDRs) in cultured NIH/3T3 and lung fibroblasts. Fibroblasts transfected with a vitamin D response element–reporter construct and exposed to the active vitamin D metabolite, 1,25(OH)₂D₃, showed increased promoter activity indicating VDR functionality in these cells. Testing the effects of 1,25(OH)₂D₃ on fibroblasts treated with transforming growth factor β1 (TGFβ1), considered a driver of many fibrotic disorders, we found that 1,25(OH)₂D₃ inhibited TGFβ1-induced fibroblast proliferation in a dose-dependent fashion. 1,25(OH)₂D₃ also inhibited TGFβ1 stimulation of α-smooth muscle actin expression and polymerization and prevented the upregulation of fibronectin and collagen in TGFβ1-treated fibroblasts. Finally, we examined how 1,25(OH)₂D₃ affects epithelial–mesenchymal transformation of lung epithelial cells upon exposure to TGFβ1. We showed that the TGFβ1-induced upregulation of mesenchymal cell markers and abnormal expression of epithelial cell markers were blunted by 1,25(OH)₂D₃. These observations suggest that under TGFβ1 stimulation, 1,25(OH)₂D₃ inhibits the pro-fibrotic phenotype of lung fibroblasts and epithelial cells.     

Latent transforming growth factor β-binding protein-3 and fibulin-1C interact with the extracellular domain of the heparin-binding EGF-like growth factor precursor

Background  

The membrane-bound cell-surface precursor and soluble forms of heparin-binding epidermal growth factor-like growth factor (HB-EGF) contribute to many cellular developmental processes. The widespread occurrence of HB-EGF in cell and tissue types has led to observations of its role in such cellular and tissue events as tumor formation, cell migration, extracellular matrix formation, wound healing, and cell adherence. Several studies have reported the involvement of such extracellular matrix proteins as latent transforming growth factor β-binding protein, TGF-β, and fibulin-1 in some of these processes. To determine whether HB-EGF interacts with extracellular matrix proteins we used the extracellular domain of proHB-EGF in a yeast two-hybrid system to screen a monkey kidney cDNA library. cDNA clones containing nucleotide sequences encoding domains of two proteins were obtained and their derived amino acid sequences were evaluated.     

Serum levels of transforming growth factor β1 and C-reactive protein as possible markers of intra uterine insemination outcome

Objective

Maternal immunity is important for the implantation phase, and exaggerated inflammatory responses may reduce the chance of implantation and pregnancy. Transforming growth factor β1 (TGF-β1) plays a role in the modulation of cellular growth, maturation and differentiation, extracellular matrix formation, immunoregulation, and apoptosis. In this study, we aimed to evaluate the changes in serum TGF-β1 and C-reactive protein (CRP) levels in infertile women following intrauterine insemination (IUI) according to the presence of pregnancy.

Methods

Sixty-three infertile patients were selected for the study in a nine-month period. Clomiphene citrate or recombinant gonadotropins were used for ovulation induction, and all patients underwent IUI following human chorionic gonadotropin (hCG) trigger. The pregnant and non-pregnant groups’ TGF-β1 and CRP levels were measured.

Results

The CRP levels increased significantly from the day of the hCG trigger to the 8th day after hCG trigger in the non-pregnant group (P = 0.003) whereas TGF-β1 levels decreased in the pregnant group (P = 0.001).

Conclusion

Maternal inflammatory responses play an important role in the occurrence of pregnancy. Changes in the levels of TGF-β1 and CRP may have a role in the outcome of IUI. Serial measurements of TGF-β1 and C-reactive protein, if confirmed by larger studies, may become valuable in predicting the outcome of IUI.

     

Comparison of transforming growth factor β and a human tumour-derived suppressor factor

Summary Serum-free supernatants from the human melanoma cell line G361 contain a factor that can potently suppress the generation of tumouricidal lymphokine-activated killer (LAK) cells in response to interleukin-2. To characterise the suppressive factor of tumour origin we performed a number of physicochemical and functional comparisons with another immunosuppressive protein, transforming growth factor (TGF). The bioactivity of tumour-derived suppressor factor (TDSF), assayed by suppression of LAK cell generation, was unaffected by a reducing agent but lost when denatured with a chaotropic agent. In contrast, TGF was inactivated by reduction but not denaturation. TDSF lost bioactivity in conditions of pH less than 4, whereas TGF showed no loss of activity. The TDSF moiety has an estimated pI of 4.3 and a molecular mass of 69–87 kDa. This differs from published values of pI 9.5, and 25 kDa molecular mass for TGF. Anti-TGF antiserum reversed the effects of TGF but did not affect the suppression of LAK cell generation caused by TDSF. These findings provide compelling evidence that the TDSF moiety is not TGF, and may be a novel immunoregulatory cytokine.     

Isogenic mesenchymal stem cells transplantation improves a rat model of chronic aristolochic acid nephropathy via upregulation of hepatic growth factor and downregulation of transforming growth factor β1

Chronic aristolochic acid (AA) nephropathy (CAAN) caused by intake of AA-containing herbs is difficult to treat. We evaluated the therapeutic effect of bone marrow (BM) mesenchymal stem cells (MSCs) on a rat model of CAAN. Female Wistar rats were fed with decoction of Caulis Aristolochia manshuriensis by intragastric administration. MSCs were prepared from BM of male Wistar rats and injected into female CAAN rats through tail vein. Body weight, renal function, and urinary excretion of these CAAN rats were monitored before killing at the end of the 20th week. Blood, urine, and tissue samples were collected from experimental (MSC and non-MSC) and normal control groups. All animals developed renal fibrosis after 12 weeks of intake of AA-containing decoction. Fibrosis in the MSC groups was significantly reduced as examined with light and electron microscopy. Blood urea nitrogen, serum creatinine, and urine protein levels were significantly reduced and hemoglobin levels were improved in the MSC group as compared with the non-MSC group (p < 0.01). The expression of TGF-β1 mRNA and protein was reduced but hepatic growth factor (HGF) was increased in the MSC group compared with the non-MSC group, but still higher than the normal control level as measured by immunochemical, RT-PCR, and western blotting assays (p < 0.01). The renal fibrosis of CAAN could be protected by isogenic MSC transplantation, probably via upregulation of HGF and downregulation of TGF-β1.     

Sprouty is a negative regulator of transforming growth factor β-induced epithelial-to-mesenchymal transition and cataract

Fibrosis affects an extensive range of organs and is increasingly acknowledged as a major component of many chronic disorders. It is now well accepted that the elevated expression of certain inflammatory cell-derived cytokines, especially transforming growth factor β (TGFβ), is involved in the epithelial-to-mesenchymal transition (EMT) leading to the pathogenesis of a diverse range of fibrotic diseases. In lens, aberrant TGFβ signaling has been shown to induce EMT leading to cataract formation. Sproutys (Sprys) are negative feedback regulators of receptor tyrosine kinase (RTK)-signaling pathways in many vertebrate systems, and in this study we showed that they are important in the murine lens for promoting the lens epithelial cell phenotype. Conditional deletion of Spry1 and Spry2 specifically from the lens leads to an aberrant increase in RTK-mediated extracellular signal-regulated kinase 1/2 phosphorylation and, surprisingly, elevated TGFβ-related signaling in lens epithelial cells, leading to an EMT and subsequent cataract formation. Conversely, increased Spry overexpression in lens cells can suppress not only TGFβ-induced signaling, but also the accompanying EMT and cataract formation. On the basis of these findings, we propose that a better understanding of the relationship between Spry and TGFβ signaling will not only elucidate the etiology of lens pathology, but will also lead to the development of treatments for other fibrotic-related diseases associated with TGFβ-induced EMT.     

Effects of transforming growth factor β1 and basic fibroblast growth factor on lipoprotein lipase activity in primary cultures of chicken (Gallus domesticus) adipocyte precursors

• 1.1. The effect of TGF-β and bFGF on lipoprotein lipase activity in chicken adipocyte precursors was investigated.
• 2.2. Lipoprotein lipase activity was reduced by up to 80% by incubation with TGF-β whereas bFGF had no effect.
• 3.3. Contrary to that found with the 3T3-L1 preadipocyte cell line it was not necessary for TGF-β to be present prior to the start of differentiation in order to be effective.
• 4.4. Incubation of adipocyte precursors with actinomycin D abolished the effect of TGF-β suggesting that synthesis of a protein effector is required.
• 5.5. These results indicate differences in responsiveness to TGF-β and bFGF between primary chicken adipocyte precursors and some preadipocyte cell lines.

     

The involvement of p38 MAPK in transforming growth factor β1－induced apoptosis in murine hepatocytes

INTRODUCTIONApoptosis is a fundamental important biologicalprocess that is required to maintain the integrity andhomeostasis of multicenular organism[1]. It seemsthat apoptosis is a predominant type of active cendeath in the liver. Endogenous factors, such astransforming growth factor FI (TGF-gi), activin A,CD95 ligand, and tumor necrosis factor (TNF) maybe involved in induction of apoptosis in the liver[2].transforming growth factor P (TGF-P) is amember of a super-family of multifu…     

Association between transforming growth factor β1 polymorphisms and atrial fibrillation in essential hypertensive subjects

Background  

The association of TGF β1 polymorphisms and atrial fibrillation (AF) in essential hypertensive (EH) subjects remains unknown. Methods EH subjects with AF (EH+AF+) and sinus rhythm (EH+AF-) were enrolled. The polymorphisms of +869 T → C at codon 10 and + 915 G → C at codon 25, were genotyped. The clinical characteristics including serum TGF β1 levels were detected.     

CD24 regulates cell proliferation and transforming growth factor β-induced epithelial to mesenchymal transition through modulation of integrin β1 stability

To determine the role of CD24 in breast cancer cells, we knocked down CD24 in MCF-7 human breast cancer cells by retroviral delivery of shRNA. MCF-7 cells with knocked down CD24 (MCF-7 hCD24 shRNA) exhibited decreased cell proliferation and cell adhesion as compared to control MCF-7 mCD24 shRNA cells. Decreased proliferation of MCF-7 hCD24 shRNA cells resulted from the inhibition of cell cycle progression from G1 to S phase. The specific inhibition of MEK/ERK signaling by CD24 ablation might be responsible for the inhibition of cell proliferation. Phosphorylation of Src/FAK and TGF-β1-mediated epithelial to mesenchymal transition was also down-regulated in MCF-7 hCD24 shRNA cells. Reduced Src/FAK activity was caused by a decrease in integrin β1 bound with CD24 and subsequent destabilization of integrin β1. Our results suggest that down-regulation of Raf/MEK/ERK signaling via Src/FAK may be dependent on integrin β1 function and that this mechanism is largely responsible for the CD24 ablation-induced decreases in cell proliferation and epithelial to mesenchymal transition.     

Expression of human transforming growth factor β1 in E. coli (I) --Direct expression in cytoplasm

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