TGF-β1 inhibits human trophoblast cell invasion by upregulating kisspeptin expression through ERK1/2 but not SMAD signaling pathway

BACKGROUND

Tightly regulation of extravillous cytotrophoblast (EVT) cell invasion is critical for the placentation and establishment of a successful pregnancy. Insufficient EVT cell invasion leads to the development of preeclampsia (PE) which is a leading cause of maternal and perinatal mortality and morbidity. Transforming growth factor-beta1 (TGF-β1) and kisspeptin are expressed in the human placenta and have been shown to inhibit EVT cell invasion. Kisspeptin is a downstream target of TGF-β1 in human breast cancer cells. However, whether kisspeptin is regulated by TGF-β1 and mediates TGF-β1-suppressed human EVT cell invasion remains unclear.

METHODS

The effect of TGF-β1 on kisspeptin expression and the underlying mechanisms were explored by a series of in vitro experiments in a human EVT cell line, HTR-8/SVneo, and primary cultures of human EVT cells. Serum levels of TGF-β1 and kisspeptin in patients with or without PE were measured by ELISA.

RESULTS

TGF-β1 upregulates kisspeptin expression in HTR-8/SVneo cells and primary cultures of human EVT cells. Using pharmacological inhibitor and siRNA, we demonstrate that the stimulatory effect of TGF-β1 on kisspeptin expression is mediated via the ALK5 receptor. Treatment with TGF-β1 activates SMAD2/3 canonical pathways as well as ERK1/2 and PI3K/AKT non-canonical pathways. However, only inhibition of ERK1/2 activation attenuates the stimulatory effect of TGF-β1 on kisspeptin expression. In addition, siRNA-mediated knockdown of kisspeptin attenuated TGF-β1-suppressed EVT cell invasion. Moreover, we report that serum levels of TGF-β1 and kisspeptin are significantly upregulated in patients with PE.

CONCLUSIONS

By illustrating the potential physiological role of TGF-β1 in the regulation of kisspeptin expression, our results may serve to improve current strategies used to treat placental diseases.

Distal Enhancer Potentiates Activin- and GnRH-Induced Transcription of FSHB

FSH is critical for fertility. Transcription of FSHB, the gene encoding the beta subunit, is rate-limiting in FSH production and is regulated by both GnRH and activin. Activin signals through SMAD transcription factors. Although the mechanisms and importance of activin signaling in mouse Fshb transcription are well-established, activin regulation of human FSHB is less well understood. We previously reported a novel enhancer of FSHB that contains a fertility-associated single nucleotide polymorphism (rs10031006) and requires a region resembling a full (8 base-pair) SMAD binding element (SBE). Here, we investigated the role of the putative SBE within the enhancer in activin and GnRH regulation of FSHB. In mouse gonadotrope-derived LβT2 cells, the upstream enhancer potentiated activin induction of both the human and mouse FSHB proximal promoters and conferred activin responsiveness to a minimal promoter. Activin induction of the enhancer required the SBE and was blocked by the inhibitory SMAD7, confirming involvement of the classical SMAD signaling pathway. GnRH induction of FSHB was also potentiated by the enhancer and dependent on the SBE, consistent with known activin/GnRH synergy regulating FSHB transcription. In DNA pull-down, the enhancer SBE bound SMAD4, and chromatin immunoprecipitation demonstrated SMAD4 enrichment at the enhancer in native chromatin. Combined activin/GnRH treatment elevated levels of the active transcriptional histone marker, histone 3 lysine 27 acetylation, at the enhancer. Overall, this study indicates that the enhancer is directly targeted by activin signaling and identifies a novel, evolutionarily conserved mechanism by which activin and GnRH can regulate FSHB transcription.

The role of microRNAs in the osteogenic and chondrogenic differentiation of mesenchymal stem cells and bone pathologies

Mesenchymal stem cells (MSCs) have been identified in many adult tissues. MSCs can regenerate through cell division or differentiate into adipocytes, osteoblasts and chondrocytes. As a result, MSCs have become an important source of cells in tissue engineering and regenerative medicine for bone tissue and cartilage. Several epigenetic factors are believed to play a role in MSCs differentiation. Among these, microRNA (miRNA) regulation is involved in the fine modulation of gene expression during osteogenic/chondrogenic differentiation. It has been reported that miRNAs are involved in bone homeostasis by modulating osteoblast gene expression. In addition, countless evidence has demonstrated that miRNAs dysregulation is involved in the development of osteoporosis and bone fractures. The deregulation of miRNAs expression has also been associated with several malignancies including bone cancer. In this context, bone-associated circulating miRNAs may be useful biomarkers for determining the predisposition, onset and development of osteoporosis, as well as in clinical applications to improve the diagnosis, follow-up and treatment of cancer and metastases. Overall, this review will provide an overview of how miRNAs activities participate in osteogenic/chondrogenic differentiation, while addressing the role of miRNA regulatory effects on target genes. Finally, the role of miRNAs in pathologies and therapies will be presented.

TGFβ signaling networks in ovarian cancer progression and plasticity

Epithelial ovarian cancer (EOC) is a leading cause of cancer-related death in women. Late-stage diagnosis with significant tumor burden, accompanied by recurrence and chemotherapy resistance, contributes to this poor prognosis. These morbidities are known to be tied to events associated with epithelial-mesenchymal transition (EMT) in cancer. During EMT, localized tumor cells alter their polarity, cell-cell junctions, cell-matrix interactions, acquire motility and invasiveness and an exaggerated potential for metastatic spread. Key triggers for EMT include the Transforming Growth Factor-β (TGFβ) family of growth factors which are actively produced by a wide array of cell types within a specific tumor and metastatic environment. Although TGFβ can act as either a tumor suppressor or promoter in cancer, TGFβ exhibits its pro-tumorigenic functions at least in part via EMT. TGFβ regulates EMT both at the transcriptional and post-transcriptional levels as outlined here. Despite recent advances in TGFβ based therapeutics, limited progress has been seen for ovarian cancers that are in much need of new therapeutic strategies. Here, we summarize and discuss several recent insights into the underlying signaling mechanisms of the TGFβ isoforms in EMT in the unique metastatic environment of EOCs and the current therapeutic interventions that may be relevant.

Arecoline suppresses epithelial cell viability by upregulating tropomyosin-1 through the transforming growth factor-β/Smad pathway

CONTEXT

Oral submucous fibrosis (OSF) is a chronic and progressive disease. Arecoline, present in betel nuts, has been proposed as a vital aetiological factor. However, the underlying mechanism remains unclear.

OBJECTIVES

This research elucidates the expression of tropomyosin-1 (TPM1) and its regulation mechanism in HaCaT cells treated with arecoline.

MATERIALS AND METHODS

HaCaT cells were assigned into three groups: (1) Control; (2) Treated with arecoline (0.16 mM) for 48 h (3) Treated with arecoline (0.16 mM) and transfected with small interfering RNA (siRNA) for TPM1 (50 nM) for 48 h. CCK8, cell cycle, and apoptosis phenotypic analyses were performed. PCR and western blot analyses were performed to detect the expression level of TPM1 and examine the related signalling pathway.

RESULTS

The IC₅₀ of arecoline was approximately 50 μg/mL (0.21 mM). The arecoline dose (0.16 mM) and time (48 h) markedly increased TPM1 expression at the mRNA and protein levels in HaCaT cells. Arecoline suppressed the cell growth, caused cell cycle arrest at the G1 phase, and induced cell apoptosis in HaCaT cells. siRNA-mediated knockdown of TPM1 attenuated the effect of arecoline on cell proliferation, apoptosis, and cell cycle arrest at the G1 phase. Furthermore, blocking of the transforming growth factor (TGF)-β receptor using SB431542 significantly suppressed TPM1 expression in the cells treated with arecoline.

DISCUSSION AND CONCLUSIONS

Arecoline suppresses HaCaT cell viability by upregulating TPM1 through the TGF-β/Smad signalling pathway. This research provides a scientific basis for further study of arecoline and TPM1 in OSF and can be generalised to broader pharmacological studies. TPM1 may be a promising molecular target for treating OSF.

Si-Miao-Yong-An decoction attenuates cardiac fibrosis via suppressing TGF-β1 pathway and interfering with MMP-TIMPs expression

BACKGROUND

Myocardial fibrosis is an important pathological feature of pressure overload cardiac remodeling. Si-Miao-Yong-An decoction (SMYAD), a traditional Chinese formula, is now clinically used in the treatment of cardiovascular diseases in China. However, its mechanisms in the prevention of heart failure are not fully revealed.

PURPOSE

To determine whether treatment with SMYAD for 4 weeks would lead to changes in collagen metabolism and ventricular remodeling in a mice model of heart failure.

METHODS

Mice were subjected to transverse aorta constriction to generate pressure overload induced cardiac remodeling and then were administered SMYAD (14.85 g/kg/day) or captopril (16.5 mg/kg/day) intragastrically for 4 weeks after surgery. Echocardiography and immunohistochemical examination were used to evaluate the effects of SMYAD. The mRNA of collagen metabolism biomarkers were detected. Protein expression of TGF-β1/Smad and TGF-β1/TAK1/p38 pathway were assessed by Western blot.

RESULTS

SMYAD significantly improved cardiac function, increased left ventricle ejection fraction, and decreased fibrosis area and αSMA expression. Moreover, SMYAD reduced proteins expression related to collagen metabolism, including Col1, Col3, TIMP2 and CTGF. The increased levels of TGF-β1, Smad2, and Smad3 phosphorylation were attenuated in SMYAD group. In addition, SMYAD reduced the levels of TGF-β1, p-TAK1 and p-p38 compared with TAC group.

CONCLUSIONS

SMYAD improved cardiac fibrosis and heart failure by inhibition of TGF-β1/Smad and TGF-β1/TAK1/p38 pathway. SMYAD protected against cardiac fibrosis and maintained collagen metabolism balance by regulating MMP-TIMP expression. Taken together, these results indicate that SMYAD might be a promising therapeutic agent against cardiac fibrosis.

Integrin-Linked Kinase Deficiency in Collecting Duct Principal Cell Promotes Necroptosis of Principal Cell and Contributes to Kidney Inflammation and Fibrosis

BACKGROUND

Necroptosis is a newly discovered cell death pathway that plays a critical role in AKI. The involvement of integrin-linked kinase (ILK) in necroptosis has not been studied.

METHODS

We performed experiments in mice with an Ilk deletion in collecting duct (CD) principal cells (PCs), and cultured tubular epithelial cells treated with an ILK inhibitor or ILK siRNA knockdown.

RESULTS

Ilk deletion in CD PCs resulted in acute tubular injury and early mortality in mice. Progressive interstitial fibrosis and inflammation associated with the activation of the canonical TGF-β signaling cascade were detected in the kidneys of the mice lacking ILK in the CD PCs. In contrast to the minimal apoptosis detected in the animals' injured CDs, widespread necroptosis was present in ILK-deficient PCs, characterized by cell swelling, deformed mitochondria, and rupture of plasma membrane. In addition, ILK deficiency resulted in increased expression and activation of necroptotic proteins MLKL and RIPK3, and membrane translocation of MLKL in CD PCs. ILK inhibition and siRNA knockdown reduced cell survival in cultured tubular cells, concomitant with increased membrane accumulation of MLKL and/or phospho-MLKL. Administration of a necroptosis inhibitor, necrostatin-1, blocked cell death in vitro and significantly attenuated inflammation, interstitial fibrosis, and renal failure in ILK-deficient mice.

CONCLUSIONS

The study demonstrates the critical involvement of ILK in necroptosis through modulation of the RIPK3 and MLKL pathway and highlights the contribution of CD PC injury to the development of inflammation and interstitial fibrosis of the kidney.

TGF-β/Smad and Renal Fibrosis

Renal fibrosis is characterized by excessive deposition of extracellular matrix (ECM) that disrupts and replaces functional parenchyma, which leads to organ failure. It is known as the major pathological mechanism of chronic kidney disease (CKD). Although CKD has an impact on no less than 10% of the world population, therapeutic options are still limited. Regardless of etiology, elevated TGF-β levels are highly correlated with the activated pro-fibrotic pathways and disease progression. TGF-β, the key driver of renal fibrosis, is involved in a dynamic pathophysiological process that leads to CKD and end-stage renal disease (ESRD). It is becoming clear that epigenetics regulates renal programming, and therefore, the development and progression of renal disease. Indeed, recent evidence shows TGF-β1/Smad signaling regulates renal fibrosis via epigenetic-correlated mechanisms. This review focuses on the function of TGF-β/Smads in renal fibrogenesis, and the role of epigenetics as a regulator of pro-fibrotic gene expression.

Regulation of Foxe1 by Thyrotropin and Transforming Growth Factor Beta Depends on the Interplay Between Thyroid-Specific, CREB and SMAD Transcription Factors

Background: Thyroid follicular cells are characterized by the expression of a specific set of genes necessary for the synthesis and secretion of thyroid hormones, which are in turn regulated by the transcription factors Nkx2-1, Pax8, and Foxe1. Thyroid differentiation is finely tuned by the balance between positive regulatory signals, including thyrotropin (TSH), and by negative regulatory signals, such as transforming growth factor beta (TGF-β), which counteracts the action of TSH. A role for Foxe1 as a mediator of hormonal and growth-factor control of thyroid differentiation has been previously suggested. Therefore, the aim of this work was to study the mechanisms governing Foxe1 expression to define the ligands and signals that regulate one of the important factors in thyroid differentiation. Methods: Expression of Foxe1 was evaluated in rat PCCl3 thyroid follicular cells under different treatments. The mouse Foxe1 promoter was cloned, and site-directed mutagenesis was undertaken to study its transcriptional regulation and to identify response elements. Protein/DNA binding assays were performed to evaluate the binding of different transcription factors, and gene-silencing approaches were used to elucidate their functional roles. Results:In silico analysis of the Foxe1 promoter identified binding sites for Nkx2-1, Pax8, Foxe1, and Smad proteins, as well as cAMP-response element (CRE) sites. It was found that both CRE-binding protein and CRE modulator were necessary for the TSH-mediated induction of Foxe1 expression via the cAMP/PKA signaling pathway. Moreover, transcription of Foxe1 was regulated by Nkx2-1 and Pax8 and by itself, suggesting an autoregulatory mechanism of activation and an important role for thyroid transcription factors. Finally, TGF-β, through Smad proteins, inhibited the TSH-induced Foxe1 expression. Conclusions: This study shows that Foxe1 is the final target of TSH/cAMP and TGF-β regulation that mediates expression of thyroid differentiation genes, and provides evidence of an interplay between CRE-binding proteins, thyroid transcription factors, and Smad proteins in its regulation. Thus, Foxe1 plays an important role in the complex transcriptional network that regulates thyroid follicular cell differentiation.

Discoidin-domain receptor coordinates cell-matrix adhesion and collective polarity in migratory cardiopharyngeal progenitors

Integrated analyses of regulated effector genes, cellular processes, and extrinsic signals are required to understand how transcriptional networks coordinate fate specification and cell behavior during embryogenesis. Ciona cardiopharyngeal progenitors, the trunk ventral cells (TVCs), polarize as leader and trailer cells that migrate between the ventral epidermis and trunk endoderm. We show that the TVC-specific collagen-binding Discoidin-domain receptor (Ddr) cooperates with Integrin-β1 to promote cell-matrix adhesion. We find that endodermal cells secrete a collagen, Col9-a1, that is deposited in the basal epidermal matrix and promotes Ddr activation at the ventral membrane of migrating TVCs. A functional antagonism between Ddr/Intβ1-mediated cell-matrix adhesion and Vegfr signaling appears to modulate the position of cardiopharyngeal progenitors between the endoderm and epidermis. We show that Ddr promotes leader-trailer-polarized BMP-Smad signaling independently of its role in cell-matrix adhesion. We propose that dual functions of Ddr integrate transcriptional inputs to coordinate subcellular processes underlying collective polarity and migration.

Vitamin C deficiency exacerbates diabetic glomerular injury through activation of transforming growth factor-β signaling

BACKGROUND

The hyperglycemia and hyperoxidation that characterize diabetes lead to reduced vitamin C (VC) in diabetic humans and experimentally diabetic animals. Herein, we access the effects of VC deficiency on the diabetic kidney injury and explore the underlying mechanism.

METHODS

l-gulonolactone oxidase conventional knockout (Gulo-/-) mice genetically unable to synthesize VC were subjected to streptozotocin-induced diabetic kidney injury and the role of VC deficiency was evaluated by biochemical and histological approaches. Rat mesangial cells were cultured to investigate the underlying mechanism.

RESULTS

Functionally, VC deficiency aggravates the streptozotocin-induced renal insufficiency, exhibiting the increased urine albumin, water intake, and urine volume in Gulo-/- mice. Morphologically, VC deficiency exacerbates the streptozotocin-induced kidney injury, exhibiting the increased glomerular expansion, deposition of Periodic Acid-Schiff- and Masson-positive materials, and expression of α-smooth muscle actin, fibronectin and type 4 collagen in glomeruli of Gulo-/- mice. Mechanistically, VC activates protein kinase B (Akt) to destabilize Ski and thereby induce the expression of Smad7, resulting in suppression of TGF-β/Smad signaling and extracellular matrix deposition in mesangial cells.

CONCLUSIONS

VC is essential for the renal function maintenance in diabetes.

GENERAL SIGNIFICANCE

Compensation for the loss of VC could be an effective remedy for diabetic kidney injury.

The TGF-β Family in Caenorhabditis elegans

Transforming growth factor β (TGF-β) and related ligands have potent effects on an enormous diversity of biological functions in all animals examined. Because of the strong conservation of TGF-β family ligand functions and signaling mechanisms, studies from multiple animal systems have yielded complementary and synergistic insights. In the nematode Caenorhabditis elegans, early studies were instrumental in the elucidation of TGF-β family signaling mechanisms. Current studies in C. elegans continue to identify new functions for the TGF-β family in this organism as well as new conserved mechanisms of regulation.

Extracellular calcium promotes bone formation from bone marrow mesenchymal stem cells by amplifying the effects of BMP-2 on SMAD signalling

Understanding the molecular events that regulate osteoblast differentiation is essential for the development of effective approaches to bone regeneration. In this study, we analysed the osteoinductive properties of extracellular calcium in bone marrow-derived mesenchymal stem cell (BM-MSC) differentiation. We cultured BM-MSCs in 3D gelatin scaffolds with Ca²⁺ and BMP-2 as osteoinductive agents. Early and late osteogenic gene expression and bone regeneration in a calvarial critical-size defect model demonstrate that extracellular Ca²⁺ enhances the effects of BMP-2 on Osteocalcin, Runx2 and Osterix expression and promotes bone regeneration in vivo. Moreover, we analysed the molecular mechanisms involved and observed an antagonistic effect between Ca²⁺ and BMP-2 on SMAD1/5, ERK and S6K signalling after 24 hours. More importantly, a cooperative effect between Ca²⁺ and BMP-2 on the phosphorylation of SMAD1/5, S6, GSK3 and total levels of β-CATENIN was observed at a later differentiation time (10 days). Furthermore, Ca²⁺ alone favoured the phosphorylation of SMAD1, which correlates with the induction of Bmp2 and Bmp4 gene expression. These data suggest that Ca²⁺ and BMP-2 cooperate and promote an autocrine/paracrine osteogenic feed-forward loop. On the whole, these results demonstrate the usefulness of calcium-based bone grafts or the addition of exogenous Ca²⁺ in bone tissue engineering.

Halofuginone inhibits radiotherapy-induced epithelial-mesenchymal transition in lung cancer

Radiotherapy is used to treat many different human tumors. Paradoxically, radiation can activate TGF-β1 signaling and induce the epithelial-mesenchymal transition (EMT), which is associated with enhanced tumor progression. This study investigated the inhibitory effects of halofuginone, a plant-derived alkaloid that has been shown to inhibit TGF-β1 signaling, on radiation-induced EMT and explored the underlying mechanisms using a Lewis lung carcinoma (LLC) xenograft model. The cells and animals were divided into five treatment groups: Normal Control (NC), Halofuginone alone (HF), Radiotherapy alone (RT), Radiotherapy combined with Halofuginone (RT+HF), and Radiotherapy combined with the TGF-β1 inhibitor SB431542 (RT+SB). Radiation induced EMT in lung cancer cells and xenografts, as evidenced by increased expression of the mesenchymal markers N-cadherin and Vimentin, and reduced expression of the epithelial markers E-cadherin and Cytokeratin. Further, radiotherapy treatment increased the migration and invasion of LLC cells. Halofuginone reversed the EMT induced by radiotherapy in vitro and in vivo, and inhibited the migration and invasion of LLC cells. In addition, TGF-β1/Smad signaling was activated by radiotherapy and the mRNA expression of Twist and Snail was elevated; this effect was reversed by halofuginone or the TGF-β1 inhibitor SB431542. Our results demonstrate that halofuginone inhibits radiation-induced EMT, and suggest that suppression of TGF-β1 signaling may be responsible for this effect.

Enhanced Osteogenesis of Adipose-Derived Stem Cells by Regulating Bone Morphogenetic Protein Signaling Antagonists and Agonists

Although adipose-derived stem cells (ASCs) are an attractive cell source for bone tissue engineering, direct use of ASCs alone has had limited success in the treatment of large bone defects. Although bone morphogenetic proteins (BMPs) are believed to be the most potent osteoinductive factors to promote osteogenic differentiation of ASCs, their clinical applications require supraphysiological dosage, leading to high medical burden and adverse side effects. In the present study, we demonstrated an alternative approach that can effectively complement the BMP activity to maximize the osteogenesis of ASCs without exogenous application of BMPs by regulating levels of antagonists and agonists to BMP signaling. Treatment of ASCs with the amiloride derivative phenamil, a positive regulator of BMP signaling, combined with gene manipulation to suppress the BMP antagonist noggin, significantly enhanced osteogenic differentiation of ASCs through increased BMP-Smad signaling in vitro. Furthermore, the combination approach of noggin suppression and phenamil stimulation enhanced the BMP signaling and bone repair in a mouse calvarial defect model by adding noggin knockdown ASCs to apatite-coated poly(lactic-coglycolic acid) scaffolds loaded with phenamil. These results suggest novel complementary osteoinductive strategies that could maximize activity of the BMP pathway in ASC bone repair while reducing potential adverse effects of current BMP-based therapeutics.

SIGNIFICANCE

Although stem cell-based tissue engineering strategy offers a promising alternative to repair damaged bone, direct use of stem cells alone is not adequate for challenging healing environments such as in large bone defects. This study demonstrates a novel strategy to maximize bone formation pathways in osteogenic differentiation of mesenchymal stem cells and functional bone formation by combining gene manipulation with a small molecule activator toward osteogenesis. The findings indicate promising stem cell-based therapy for treating bone defects that can effectively complement or replace current osteoinductive therapeutics.

MicroRNA-29b Inhibits Endometrial Fibrosis by Regulating the Sp1-TGF-β1/Smad-CTGF Axis in a Rat Model

Intrauterine adhesions (IUAs), which are characterized by endometrial fibrosis, increase the risk of secondary infertility and recurrent miscarriage. MicroRNA-29 (miR-29) is a potent inhibitor of TGF-β1/Smad signaling. In this study, we investigated the therapeutic potential of agomir-29b, an miR-29b mimic, in endometrial fibrosis induced by dual injury (uterine curettage and lipopolysaccharide treatment) in a rat model of IUA and explored the underlying mechanism. We found that injured rats developed endometrial fibrosis characterized by increased COL1A1 and α-smooth muscle actin expression and decreased E-cadherin expression, associated with a loss of miR-29b. Overexpression of miR-29b before injury prevented endometrial fibrosis including collagen accumulation and epithelial-mesenchymal transition. Delay of agomir-29b treatment until endometrial fibrosis was established on day 4 also halted the progression of disease. Further experiments indicated that miR-29b inhibited endometrial fibrosis via blockade of the Sp1-TGF-β1/Smad-CTGF pathway. In conclusion, agomir-29b may act as a novel and effective therapeutic agent against IUAs.

Protective effect of fucoidan from Fucus vesiculosus on liver fibrosis via the TGF-β1/Smad pathway-mediated inhibition of extracellular matrix and autophagy

Liver fibrosis is a dynamic reversible pathological process in the development of chronic liver disease to cirrhosis. However, the current treatments are not administered for a long term due to their various side effects. Autophagy is initiated to decompose damaged or excess organelles, which had been found to alter the progression of liver fibrosis. In this article, we hypothesized that fucoidan from Fucus vesiculosus may attenuate liver fibrosis in mice by inhibition of the extracellular matrix and autophagy in carbon tetrachloride- and bile duct ligation-induced animal models of liver fibrosis. The results were determined using enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemical staining. Fucoidan from F. vesiculosus could inhibit the activation of hepatic stellate cells and the formation of extracellular matrix and autophagosomes, and its effect may be associated with the downregulation of transforming growth factor beta 1/Smads pathways. Fucoidan, as an autophagy and transforming growth factor beta 1 inhibitor, could be a promising potential therapeutic agent for liver fibrosis.

Effect of hesperidin on TGF-beta1/Smad signaling pathway in HSC

Liver fibrosis is a common pathological process for chronic liver injury caused by multiple etiological factors and an inevitable phase leading to liver cirrhosis. According to the previous studies, hesperidin (HDN) shows a very good protective effect on CCl4-induced chemical hepatic fibrosis in rats. In this experiment, based on the findings of the previous studies, a platelet-derived growth factor (PDGF)-induced HSC-T6 model was established to observe the inhibitory effect of HDN on HSC-T6 proliferation. The ELISA method was adopted to detect the content of collagen I in HSC-T6 supernatant. Transforming growth factor (TGF)-beta1, Smad2, Smad3, Smad7 and connective tissue growth factor (CTGF) mRNA expressions were measured by RT-PCR; TGF-beta1 and CT-GF protein expressions in HSC-T6 were determined by Western blot, in order to study HDN's effect on TGF-beta1 signaling pathway in HSC and its potential action mechanism. The results demonstrated that HDN could notably improve HSC-T6 proliferation, Collagen I growth and TGF-beta1, Smad2, Smad3 and CTGF mRNA.expressions. After being intervened with HDN, it could notably inhibit HSC-T6 proliferation and Collagen I growth, reduce TGF-beta1, Smad2, Smad3 and CTGF mRNA and TGF-beta1, CTGF protein expressions and increase Smad7 mRNA expression. HDN's antihepatic fibrosis effect may be related to the inhibition of HSC proliferation and activation by modulating TGF-beta/Smad signaling pathway.

SMADs and YAP compete to control elongation of β-catenin:LEF-1-recruited RNAPII during hESC differentiation

The Wnt3a/β-catenin and Activin/SMAD2,3 signaling pathways synergize to induce endodermal differentiation of human embryonic stem cells; however, the underlying mechanism is not well understood. Using ChIP-seq and GRO-seq analyses, we show here that Wnt3a-induced β-catenin:LEF-1 enhancers recruit cohesin to direct enhancer-promoter looping and activate mesendodermal (ME) lineage genes. Moreover, we find that LEF-1 and other hESC enhancers recruit RNAPII complexes (eRNAPII) that are highly phosphorylated at Ser5, but not Ser7. Wnt3a signaling further increases Ser5P-RNAPII at LEF-1 sites and ME gene promoters, indicating that elongation remains limiting. However, subsequent Activin/SMAD2,3 signaling selectively increases transcription elongation, P-TEFb occupancy, and Ser7P-RNAPII levels at these genes. Finally, we show that the Hippo regulator, YAP, functions with TEAD to regulate binding of the NELF negative elongation factor and block SMAD2,3 induction of ME genes. Thus, the Wnt3a/β-catenin and Activin/SMAD2,3 pathways act in concert to counteract YAP repression and upregulate ME genes during early hESC differentiation.

Endocardial fibroelastosis is caused by aberrant endothelial to mesenchymal transition

RATIONALE

Endocardial fibroelastosis (EFE) is a unique form of fibrosis, which forms a de novo subendocardial tissue layer encapsulating the myocardium and stunting its growth, and which is typically associated with congenital heart diseases of heterogeneous origin, such as hypoplastic left heart syndrome. Relevance of EFE was only recently highlighted through the establishment of staged biventricular repair surgery in infant patients with hypoplastic left heart syndrome, where surgical removal of EFE tissue has resulted in improvement in the restrictive physiology leading to the growth of the left ventricle in parallel with somatic growth. However, pathomechanisms underlying EFE formation are still scarce, and specific therapeutic targets are not yet known.

OBJECTIVE

Here, we aimed to investigate the cellular origins of EFE tissue and to gain insights into the underlying molecular mechanisms to ultimately develop novel therapeutic strategies.

METHODS AND RESULTS

By utilizing a novel EFE model of heterotopic transplantation of hearts from newborn reporter mice and by analyzing human EFE tissue, we demonstrate for the first time that fibrogenic cells within EFE tissue originate from endocardial endothelial cells via aberrant endothelial to mesenchymal transition. We further demonstrate that such aberrant endothelial to mesenchymal transition involving endocardial endothelial cells is caused by dysregulated transforming growth factor beta/bone morphogenetic proteins signaling and that this imbalance is at least in part caused by aberrant promoter methylation and subsequent transcriptional suppression of bone morphogenetic proteins 5 and 7. Finally, we provide evidence that supplementation of exogenous recombinant bone morphogenetic proteins 7 effectively ameliorates endothelial to mesenchymal transition and experimental EFE in rats.

CONCLUSIONS

In summary, our data point to aberrant endothelial to mesenchymal transition as a common denominator of infant EFE development in heterogeneous, congenital heart diseases, and to bone morphogenetic proteins 7 as an effective treatment for EFE and its restriction of heart growth.

Constitutively active FOXO1 diminishes activin induction of Fshb transcription in immortalized gonadotropes

In the present study, we investigate whether the FOXO1 transcription factor modulates activin signaling in pituitary gonadotropes. Our studies show that overexpression of constitutively active FOXO1 decreases activin induction of murine Fshb gene expression in immortalized LβT2 cells. We demonstrate that FOXO1 suppression of activin induction maps to the −304/−95 region of the Fshb promoter containing multiple activin response elements and that the suppression requires the FOXO1 DNA-binding domain (DBD). FOXO1 binds weakly to the −125/−91 region of the Fshb promoter in a gel-shift assay. Since this region of the promoter contains a composite SMAD/FOXL2 binding element necessary for activin induction of Fshb transcription, it is possible that FOXO1 DNA binding interferes with SMAD and/or FOXL2 function. In addition, our studies demonstrate that FOXO1 directly interacts with SMAD3/4 but not SMAD2 in a FOXO1 DBD-dependent manner. Moreover, we show that SMAD3/4 induction of Fshb-luc and activin induction of a multimerized SMAD-binding element-luc are suppressed by FOXO1 in a DBD-dependent manner. These results suggest that FOXO1 binding to the proximal Fshb promoter as well as FOXO1 interaction with SMAD3/4 proteins may result in decreased activin induction of Fshb in gonadotropes.

[Mechanisms of cordycepin on improving renal interstitial fibrosis via regulating eIF2α/TGF-β/Smad signaling pathway]

OBJECTIVE

To investigate the effects and mechanisms of cordycepin,an effective component of cordyceps militaris, on renal interstitial fibrosis (RIF) and its related eIF2α/TGF-β/Smad signaling pathway.

METHOD

Firstly, 15 C57BL/6 mice were randomly divided into 3 groups,the control group (Group A), the model group (Group B) and the cordycepin-treated group (Group C). After renal interstitial fibrotic model was successfully established by unilateral ureteral obstruction (UUO), the mice in Group C were intraperitoneally administrated with cordycepin(5 mg x kg(-1) d(-1)) and the ones in Group A and B were administrated with physiological saline for 5 days. At the end of the study, the obstructed kidneys were collected and detected for the pathological changes of RIF, and the mRNA expressions of collagen type I (Col I) and α-smooth muscle actin (α-SMA) in the kidney by Northern blot. Secondly, after renal tubular epithelial (NRK-52E) cells cultured in vitro were exposed to transforming growth factor (TGF) -β with or without cordycepin, the mRNA expressions of Col I and collagen type IV( Col IV) by Northern blot, and the protein expressions of eukaryotic initiation factor 2α (eIF2α), phosphorylated eIF2α ( p-eIF2α), Smad2/3 and phosphorylated Smad2/3 (p-Smad2/3) were tested by Western blot.

RESULT

In vivo, cordycepin alleviated RIF in model mice, including improving fibrotic pathological characteristics and mRNA expressions of Col I and α-SMA. In vitro, cordycepin induced the high expression of p-elF2α, and inhibited the expressions of p-Smad2/3, Col I and Col IV induced by TGF-β in NRK-52E cells.

CONCLUSION

Cordycepin attenuates RIF in vivo and in vitro, probably by inducing the phosphorylation of eIF2α, suppressing the expression of p-Smad2/3, a key signaling molecule in TGF-β/Smad signaling pathway, and reducing the expressions of collagens and α-SMA in the kidney.

TGF-β1 induces COX-2 expression and PGE2 production in human granulosa cells through Smad signaling pathways

CONTEXT

Cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) production have been shown to play key roles in the regulation of ovulation. The TGF-β superfamily members are important molecules that regulate many ovarian functions under normal physiological and pathological conditions. TGF-β1 and its receptors are expressed in human granulosa cells. However, to date, whether TGF-β1 can regulate COX-2 expression and PGE2 production, which in turn contribute to the process of ovulation, remains unknown.

OBJECTIVE

The objective of the study was to investigate the effects of TGF-β1 on COX-2 expression and PGE2 production in human granulosa cells.

DESIGN

SVOG cells are human granulosa cells that were obtained from women undergoing in vitro fertilization and immortalized with Simian virus 40 large T antigen. SVOG cells were used to investigate the effect of TGF-β1 on COX-2 expression and PGE2 production.

SETTING

The study was conducted at an academic research center.

MAIN OUTCOME MEASURES

mRNA and protein levels were examined by RT-quantitative real-time PCR and Western blotting, respectively. The concentrations of PGE2 in the culture medium were measured by an ELISA.

RESULTS

TGF-β1 treatment induced COX-2 expression and PGE2 production. The inductive effects of TGF-β1 on COX-2 and PGE2 were abolished by the inhibition of TGF-β type I receptor (TβRI). In addition, treatment with TGF-β1 activated phosphorylated mothers against decapentaplegic (Smad)-2 and Smad3 signaling pathways. Inhibition of the Smad signaling pathways by small interfering RNA-mediated approaches attenuated the TGF-β1-induced COX-2 expression and PGE2 production.

CONCLUSION

TGF-β1 induced PGE2 production by inducing the COX-2 expression through a Smad-dependent signaling pathway in human granulosa cells.

The regulation of TGF-β/SMAD signaling by protein deubiquitination

Transforming growth factor-β (TGF-β) members are key cytokines that control embryogenesis and tissue homeostasis via transmembrane TGF-β type II (TβR II) and type I (TβRI) and serine/threonine kinases receptors. Aberrant activation of TGF-β signaling leads to diseases, including cancer. In advanced cancer, the TGF-β/SMAD pathway can act as an oncogenic factor driving tumor cell invasion and metastasis, and thus is considered to be a therapeutic target. The activity of TGF-β/SMAD pathway is known to be regulated by ubiquitination at multiple levels. As ubiquitination is reversible, emerging studies have uncovered key roles for ubiquitin-removals on TGF-β signaling components by deubiquitinating enzymes (DUBs). In this paper, we summarize the latest findings on the DUBs that control the activity of the TGF-β signaling pathway. The regulatory roles of these DUBs as a driving force for cancer progression as well as their underlying working mechanisms are also discussed.

BMP growth factor signaling in a biomechanical context

Bone Morphogenetic Proteins (BMPs) are members of the transforming growth factor-β superfamily of secreted polypeptide growth factors and are important regulators in a multitude of cellular processes. To ensure the precise and balanced propagation of their pleiotropic signaling responses, BMPs and their corresponding signaling pathways are subject to tight control. A large variety of regulatory mechanisms throughout different biological levels combines into a complex network and provides the basis for physiological BMP function. This regulatory network not only includes biochemical factors but also mechanical cues. Both BMP signaling and mechanotransduction pathways are tightly interconnected and represent an elaborate signaling network active during development but also during organ homeostasis. Moreover, its dysregulation is associated with a number of human pathologies. A more detailed understanding of this crosstalk in respect to molecular interactions will be indispensable in the future, in particular to understand BMP-related diseases as well as with regard to an efficient clinical application of BMP ligands.

[Involvement of Smad pathway in proteoglycan 4 expression induced by hydrostatic pressure in temporomandibular synovial fibroblasts]

OBJECTIVE

To examine the expression of proteoglycan 4 (PRG-4) induced by hydrostatic pressure in rat temporomandibular synovial fibroblasts and investigate the possible mechanism.

METHODS

The cultured rat temporomandibular synovial fibroblasts were subjected to 100 kPa magnitude intermittent hydrostatic pressure (IHP) at frequency of 4 h/day, and the static group served as control. The expressions of Smad pathway proteins and p38MAPK pathway proteins were analyzed by Western blot and immunofluorescence staining. Then the cells were incubated with SB431542, the inhibitor of transforming growth factor (TGF)-β receptor. Western blot and reverse transcription PCR were used to detect the PRG-4 expression after 72 h.

RESULTS

The expression of phosphorylated Smad-2 and phosphorylated Smad-3 were increased after 1 h of IHP, reaching a maximum after 2 h and 4 h of IHP, respectively.However, the protein content of phosphorylated p38 did not vary significantly. In addition, IHP induced nuclear translocation of Smad-2/-3, and the immunofluorescence staining signal intensity markedly increased (24.11 ± 4.70)(P < 0.05). The levels of PRG-4 mRNA were significantly increased by IHP (1.48 ± 0.08)(P < 0.05). Treatment of cells with SB431542 could decrease the expression of PRG-4 mRNA significantly after IHP (0.47 ± 0.05)(P < 0.05). In addition, SB431542 inhibited the expression of PRG-4 protein induced by IHP.

CONCLUSIONS

Smad signal acts as an essential signal pathway to regulate PRG-4 expression induced by IHP.

Immunopathogenesis of psoriasis: a possible role of TGFbeta/Smads pathway

Psoriasis is a chronic immune-mediated inflammatory skin disease with both genetic and environmental factors contributing to its pathogenesis. Transforming Growth Factor beta (TGFbeta) is a member of a large family of pleiotropic cytokines with three different isoforms (TGFbeta1,2,3). Smads are a family of eight-related proteins that function as intracellular signaling intermediates for TGFbeta once the latter is bound to its receptors (TGFbRI, II and III). The involvement of Smads in TGFbeta signaling has been studied intensively in the skin in the process of wound healing. Few studies, and with controversial results, have investigated at the immunohistochemical and molecular level the role of TGFbeta/Smads signaling in psoriasis.

[Effect of compound panax notoginsenoside granules on TGF-β1/Smads signaling pathway in rats with bleomycin-induced pulmonary fibrosis]

OBJECTIVE

To investigate the intervention effects and mechanisms of the compound panax notoginsenoside granules (CPNG) on bleomycin-induced pulmonary fibrosis in rats.

METHODS

Sixty male Sprague-Dawley rats were randomly divided into 6 groups, including normal control group, model group, prednisolone group, and CPNG (high, middle and low-dose) groups. Each group included 10 Sprague-Dawley rats. Except the control group, pulmonary fibrosis model rats were injected with bleomycin (5 mg/kg) via trachea. On the second day of the bleomycin injection, the rats in each treatment group were given prednisolone (3.33 mg/kg) and corresponding doses of CPNG (100, 50, 25 mg/kg) by nasogastric feeding daily; the normal control group and the model group were given the equal volume distilled water daily. Twenty-eight days later, all rats were executed and the lung tissues were subjected to the histopathological examination via HE and Masson staining. The hydroxyproline (HYP) in lung tissues was assessed by alkaline hydrolysis. The expressions of TGF-β1, Smad2, and Smad7 proteins were analyzed by Western blotting.

RESULTS

Compared with the model group, the histopathological results revealed that CPNG dramatically decreased the severity of lung inflammation and fibrosis in rats (P<0.01). Compared with the control group, the HYP in lung tissues was reduced in all of the CPNG groups (P<0.01). Moreover, CPNG inhibited the expressions of TGF-β1 or Smad2 proteins (P<0.01), but enhanced the expression of Smad7 protein in the rat lung tissues (P<0.01).

CONCLUSION

CPNG has the prevention and treatment effect on the bleomycin-induced pulmonary fibrosis in rats, and it might be attributed to the regulation on the TGF-β1/Smads signaling pathway.

Role of activin A in carbon tetrachloride-induced acute liver injury

AIM: To investigate the expression and role of activin A in a mouse model of acute chemical liver injury.

METHODS: Acute liver injury in C57BL/6 male mice was induced by intraperitoneal injection with carbon tetrachloride (CCl₄) (0.5 mL/kg, body weight) dissolved in olive oil (1:19 v/v). Mice were sacrificed 1, 3, 5 and 7 d after the treatment. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum were examined and pathological changes of liver observed by hematoxylin and eosin staining to evaluate the liver injury. Activin A protein levels in serum and hepatic tissue homogenate of mice were detected by enzyme-linked immunosorbent assay, and the expression pattern of activin A protein in livers of mice was examined by immunohistochemistry. Activin type IIA receptor (ActRIIA) and Smad3 expressions in the liver were analyzed by real-time quantitative reverse transcription-polymerase chain reaction. In order to further investigate the role of activin A, we also utilized activin A blocking experiment by anti-activin A antibody (500 μg/kg, body weight) injection into mouse tail vein.

RESULTS: In CCl₄-treated mice, serum ALT and AST levels were significantly increased, compared with that in control mice (P < 0.01). Furthermore, the serious necrosis was observed around hepatic portal areas in CCl₄-treated mice. Simultaneously, activin A levels in serum and hepatic tissue homogenate of mice treated with CCl₄ for 1, 3 and 5 d increased significantly, compared with that in control mice (P < 0.01). Activin A protein expression in hepatocytes not within the necrotic area was also upregulated in mice following CCl₄ treatment. Not only activin A, but also ActRIIA and activin signaling molecule Smad3 mRNA expressions in injury liver induced by CCl₄ were significantly higher than that in control liver. In addition, levels of serum ALT and AST in CCl₄-treated mice were significantly decreased by injection of anti-activin A antibody to block endogenous activin A action, compared with that in CCl₄-treated mice by injection of immunoglobulin G instead of anti-activin A antibody (P < 0.01), and the severity of liver injury was also reduced remarkably.

CONCLUSION: These data show that activin A is involved in CCl₄-induced acute liver injury. Blocking activin A actions may be a therapeutic approach for acute liver injury.

Rnf165/Ark2C enhances BMP-Smad signaling to mediate motor axon extension

Little is known about extrinsic signals required for the advancement of motor neuron (MN) axons, which extend over long distances in the periphery to form precise connections with target muscles. Here we present that Rnf165 (Arkadia-like; Arkadia2; Ark2C) is expressed specifically in the nervous system and that its loss in mice causes motor innervation defects that originate during development and lead to wasting and death before weaning. The defects range from severe reduction of motor axon extension as observed in the dorsal forelimb to shortening of presynaptic branches of the phrenic nerve, as observed in the diaphragm. Molecular functional analysis showed that in the context of the spinal cord Ark2C enhances transcriptional responses of the Smad1/5/8 effectors, which are activated (phosphorylated) downstream of Bone Morphogenetic Protein (BMP) signals. Consistent with Ark2C-modulated BMP signaling influencing motor axons, motor pools in the spinal cord were found to harbor phosphorylated Smad1/5/8 (pSmad) and treatment of primary MN with BMP inhibitor diminished axon length. In addition, genetic reduction of BMP-Smad signaling in Ark2C (+/-) mice caused the emergence of Ark2C (-/-) -like dorsal forelimb innervation deficits confirming that enhancement of BMP-Smad responses by Ark2C mediates efficient innervation. Together the above data reveal an involvement of BMP-Smad signaling in motor axon advancement.

Smad mediated regulation of inhibitor of DNA binding 2 and its role in phenotypic maintenance of human renal proximal tubule epithelial cells

The basic-Helix-Loop-Helix family (bHLH) of transcriptional factors plays a major role in regulating cellular proliferation, differentiation and phenotype maintenance. The downregulation of one of the members of bHLH family protein, inhibitor of DNA binding 2 (Id2) has been shown to induce de-differentiation of epithelial cells. Opposing regulators of epithelial/mesenchymal phenotype in renal proximal tubule epithelial cells (PTEC), TGFβ1 and BMP7 also have counter-regulatory effects in models of renal fibrosis. We investigated the regulation of Id2 by these growth factors in human PTECs and its implication in the expression of markers of epithelial versus myofibroblastic phenotype. Cellular Id2 levels were reduced by TGFβ1 treatment; this was prevented by co-incubation with BMP7. BMP7 alone increased cellular levels of Id2. TGFβ1 and BMP7 regulated Id2 through Smad2/3 and Smad1/5 dependent mechanisms respectively. TGFβ1 mediated Id2 suppression was essential for α-SMA induction in PTECs. Although Id2 over-expression prevented α-SMA induction, it did not prevent E-cadherin loss under the influence of TGFβ1. This suggests that the loss of gate keeper function of E-cadherin alone may not necessarily result in complete EMT and further transcriptional re-programming is essential to attain mesenchymal phenotype. Although BMP7 abolished TGFβ1 mediated α-SMA expression by restoring Id2 levels, the loss of Id2 was not sufficient to induce α-SMA expression even in the context of reduced E-cadherin expression. Hence, a reduction in Id2 is critical for TGFβ1-induced α-SMA expression in this model of human PTECs but is not sufficient in it self to induce α-SMA even in the context of reduced E-cadherin.

Activin receptor-like kinase 7 suppresses lipolysis to accumulate fat in obesity through downregulation of peroxisome proliferator-activated receptor γ and C/EBPα

We previously identified a quantitative trait locus for adiposity, non-insulin-dependent diabetes 5 (Nidd5), on mouse chromosome 2. In the current study, we identified the actual genetic alteration at Nidd5 as a nonsense mutation of the Acvr1c gene encoding activin receptor-like kinase 7 (ALK7), one of the type I transforming growth factor-β receptors, which results in a COOH-terminal deletion of the kinase domain. We further showed that the ALK7 dysfunction causes increased lipolysis in adipocytes and leads to decreased fat accumulation. Conversely, ALK7 activation inhibits lipolysis by suppressing the expression of adipose lipases. ALK7 and activated Smads repress those lipases by downregulating peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein (C/EBP) α. Although PPARγ and C/EBPα act as adipogenic transcription factors during adipocyte differentiation, they are lipolytic in sum in differentiated adipocytes and are downregulated by ALK7 in obesity to accumulate fat. Under the obese state, ALK7 deficiency improves glucose tolerance and insulin sensitivity by preferentially increasing fat combustion in mice. These findings have uncovered a net lipolytic function of PPARγ and C/EBPα in differentiated adipocytes and point to the ALK7-signaling pathway that is activated in obesity as a potential target of medical intervention.

Iron chelation: inhibition of key signaling pathways in the induction of the epithelial mesenchymal transition in pancreatic cancer and other tumors

Pancreatic cancer is the fourth leading cause of cancer-related deaths worldwide in both men and women. It presents late with non-specific symptoms, which makes it difficult to diagnose until the cancer has progressed and metastasized. Metastasis is facilitated by the epithelial-to-mes-enchymal transition (EMT), which is promoted via the oncogenic transforming growth factor beta (TGFβ), Wnt, and nuclear factor kappa B (NFκB) signaling pathways. However, recent studies have demonstrated that the EMT can be inhibited by novel anti-cancer agents known as thiosemicarbazone iron chelators. These novel agents also up-regulate the metastasis suppressor, N-myc downstream regulated gene 1 (NDRG1), which can restore normal signaling to the cell and suppresses metastasis via inhibition of the EMT. Through the ability of iron chelators to up-regulate NDRG1 expression and affect multiple molecular targets, these agents have the potential to maintain the epithelial phenotype of cancer cells and may lead to improved survival rates for patients with late-stage disease.

Hexim-1 modulates androgen receptor and the TGF-β signaling during the progression of prostate cancer

BACKGROUND

Androgen and TGF-β signaling are important components during the progression of prostate cancer. However, whether common molecular events participate in the activation of these signaling pathways are less understood.

METHOD

Hexim 1 expression was detected by immunohistochemistry of human tissue microarrays and TRAMP mouse models. The in vivo significance of Hexim-1 was established by crossing the TRAMP mouse model of prostate cancer with Hexim-1 heterozygous mice. TRAMP C2 cell line was also modified to delete one copy of Hexim-1 gene to generate TRAMP-C2-Hexim-1+/- cell lines.

RESULTS

In this report, we observed that Hexim-1 protein expression is absent in normal prostate but highly expressed in adenocarcinoma of the prostate and a characteristic sub-cellular distribution among normal, benign hyperplasia, and adenocarcinoma of the prostate. Heterozygosity of the Hexim-1 gene in the prostate cancer mice model and the TRAMP-C2 cell line, leads to increased Cdk9-dependent serine phosphorylation on protein targets such as the androgen receptor (AR) and the TGF-β-dependent downstream transcription factors, such as the SMAD proteins.

CONCLUSION

Our results suggest that changes in the Hexim-1 protein expression and cellular distribution significantly influences the AR activation and the TGF-β signaling. Thus, Hexim-1 is likely to play a significant role in prostate cancer progression.

Bone morphogenetic protein signaling transcription factor (SMAD) function in granulosa cells

The transforming growth factor β (TGFβ) family of proteins are key regulators of growth and differentiation. Members of this family, including multiple TGFβs, activins, bone morphogenetic proteins (BMPs), and growth and differentiation factor 9 (GDF9), are expressed from oocytes or their associated follicular somatic cells (granulosa and thecal cells) with cell-type and stage-dependent specificity. Granulosa cells are the target cells for many of these ligands. Granulosa cell-specific knockout mice for all of the receptor-regulated SMADs, as well as the common regulatory SMAD4, have recently been generated and highlight the importance of this family in most stages of folliculogenesis. These models have also uncovered a novel role for the BMPs in suppression of granulosa cell tumor development and metastasis. This review summarizes the phenotypes of these mouse models and their contribution to our understanding of the complexity of BMP function during follicle development.

Targeting the hepcidin-ferroportin axis to develop new treatment strategies for anemia of chronic disease and anemia of inflammation

Anemia of chronic disease (ACD) or anemia of inflammation is prevalent in patients with chronic infection, autoimmune disease, cancer, and chronic kidney disease. ACD is associated with poor prognosis and lower quality of life. Management of ACD using intravenous iron and erythropoiesis stimulating agents are ineffective for some patients and are not without adverse effects, driving the need for new alternative therapies. Recent advances in our understanding of the molecular mechanisms of iron regulation reveal that increased hepcidin, the iron regulatory hormone, is a key factor in the development of ACD. In this review, we will summarize the role of hepcidin in iron homeostasis, its contribution to the pathophysiology of ACD, and novel strategies that modulate hepcidin and its target ferroportin for the treatment of ACD.

[Protective effect of TGF-beta-Smads signal-based oxymatrine on myocardial fibrosis induced by acute myocardial infarction in rats]

OBJECTIVE

To study the protective effect of oxymatrine (OMT) on myocardial fibrosis induced by acute myocardial infarction in rats and its effect on TGF-beta-Smads signal pathway.

METHOD

Arteria coronaria ligation-induced acute myocardial infarction model was established in rats. The survived rats were randomly allotted into the model group, 50, 25, 12.5 mg x kg(-1) OMT groups, the 50 mg x kg(-1) captopril group, and the Sham-operated group which was treated as the model group without the arteria coranaria ligation. After 8 weeks of ligation, myocardial fibrosis was detected by HE and Masson staining, and the RT-PCR method were used to detect the expression of mRNA of TGF-beta-Smads signal system.

RESULT

The histopathological examination showed decrease in cardiocytes, deposition of extra-cellular matrix, and increase of collagen contents after 8 weeks of ligation. RT-PCR results showed that mRNA expressions of TGF-beta1, TbetaR1, Smad2, Smad3 and Smad4 significantly increased, but mRNA expression of Smad7 is remarkable lower than the sham-operated group. Treatment with OMT for 8 weeks could remarkably inhibit myocardial fibrosis, decrease mRNA expressions of TGF-beta1, TbetaR1, Smad2, Smad3, and Smad4, and increase mRNA expressions of Smad7.

CONCLUSION

OMT has the inhibitory effect on the experimental myocardial fibrosis induced by AMI in rats. Its mechanism may be closely related to TGF-beta-Smads signal system.

Transforming growth factor β1/Smad signalling pathway of aortic disorders: histopathological and immunohistochemical studies

BACKGROUND

The aim of the present study was to evaluate the expressions and biological functions of the TGF-β(1)/Smad signalling pathway of aortic disorders by way of histopathological and immunohistochemical studies.

MATERIAL AND METHODS

Aortic specimens of 20 patients with aortic dissection, 9 patients with aortic aneurysm, 9 patients with coronary artery disease, and 5 deceased healthy adults were collected. The samples were stained with haematoxylin -eosin, Masson's trichrome, van Gieson, and alcian blue, and with immunohistochemical stainings to detect TGF-β(1), type I receptor (TβRI), Smad2/3, Smad4, and Smad7.

RESULTS

Masson's trichrome and van Gieson stainings showed attenuated collagens in the aorta of the patients with aortic dissection and aortic aneurysm. TGF-β(1), TβRI, and Smad2/3 mainly showed a cytoplasmic immunoreactivity in the aortic media, Smad4 immunoreactivity was predominantly located in the cytoplasm and/or the nucleus of the aortic media, and Smad7 immunoreactivity was present in the nucleus of the aortic media and intima. The TGF-β(1) signalling pathway proteins were similarly expressed in the aorta of aortic dissection and aortic aneurysm patients, while they were less pronounced in the aorta of coronary artery disease patients, and weak or negative in the aorta of healthy control individuals.

CONCLUSIONS

These observations support the notion that there is an association between the TGF-β(1)/Smad pathway and the pathological events of the aorta. Dysregulation of the TGF-β(1)/Smad pathway may predispose the pathologenesis of aortic disorders.

Fibrosis: is it a coactivator disease?

Fibrosis is an abnormal fibroblast-activation-associated pathological manifestation in injured organs where excessive non-physiological synthesis and accumulation of extracellular matrix (ECM) proteins by activated/differentiated fibroblasts disrupts tissue homeostasis. Like other eukaryotic genes, expression of ECM protein genes not only depends on its gene sequences in the regulatory region but also influenced by non-genetic factors called epigenetic regulators including acetyltransferases, deacetylases, methyltransferases and microRNAs. The acetyltransferase p300 (ATp300), a transcriptional coactivator, is a major player in the epigenetic regulation of genes whose products are involved in cellular growth, proliferation, apoptosis and essential for embryonic development. ATp300 acetylates specific lysine residues in histones and transcription factors (KAT) and as a transcriptional coactivator it forms a bridge between upstream regulatory element binding protein complex and basal transcriptional machinery. Abnormal coactivator activity-associated diseases are known as coactivator diseases. Abnormalities in ATp300 activities in adults are associated with numerous diseases. Here, we review the significant roles of ATp300 in epigenetic regulation of collagen synthesis and deposition in extracellular spaces, matrix remodeling and tissue fibrogenesis. The present day understanding on the distinct role of acetyltransferases, deacetylases, and deacetylase inhibitors on epigenetic regulation of matrix remodeling and fibrosis has also been discussed.

Fluorofenidone suppresses epithelial-mesenchymal transition and the expression of connective tissue growth factor via inhibiting TGF-beta/Smads signaling in human proximal tubular epithelial cells

OBJECTIVES

The present study was designed to investigate the potential effects and mechanism of fluorofenidone (AKF-PD) on transforming growth factor beta1 (TGF-beta1)-induced tubular epithelial-mesenchymal transition (EMT) and the expression of connective tissue growth factor (CTGF) in human proximal tubular epithelial cells.

METHODS

HK-2 cells were pretreated with AKF-PD, pirfenidone (PFD), Losartan, and SB431542 (an inhibitor of TGF-beta type I receptor). The pretreated HK-2 cells were subsequently co-treated with TGF-beta1 (5 ng/ml). The morphological changes of HK-2 cells were observed under an inverted microscope. Expression of alpha-SMA was detected by Western blot and immunofluorescence. The protein expression of ZO-1, fibronectin, CTGF, phosphorylated Smad2 (p-Smad2) and phosphorylated Smad3 (p-Smad3) were evaluated by Western blot.

RESULTS

Through down-regulation of p-Smad2 and p-Smad3 proteins, AKF-PD significantly inhibited protein expression of alpha-SMA, fibronectin, and CTGF. Meanwhile, the depressed ZO-1 expression and morphological changes induced by TGF-beta1 were attenuated by AKF-PD.

CONCLUSION

AKF-PD acts as an anti-fibrotic agent through blocking TGF-beta/Smads signaling and consequently inhibits TGF-beta1-induced EMT and CTGF expression in human proximal tubular epithelial cells.

Differential roles of CCN family proteins during osteoblast differentiation: Involvement of Smad and MAPK signaling pathways

CCN family proteins play diverse roles in many aspects of cellular processes such as proliferation, differentiation, adhesion, migration, angiogenesis and survival. In the bone tissue of vertebrate species, the expression of most CCN family members has been observed in osteoblasts. However, their spatial and temporal distributions, as well as their functions, are still only partially understood. In this study, we evaluated the localization of CCN family members in skeletal tissue in vivo and comparatively analyzed the gene expression patterns and functions of the members in murine osteoblasts in primary culture. Immunofluorescent analyses revealed that the CCN family members were differentially produced in osteoblasts and osteocytes. The presence of all Ccn transcripts was confirmed in those osteoblasts. Among the members, CCN1, CCN2, CCN4 and CCN5 were found in osteocytes. CCN4 and CCN5 were distributed in osteocytes located inside of bone matrix as well. Next, we investigated the expression pattern of Ccn family members during osteoblast differentiation. Along with differentiation, most of the members followed proper gene expression patterns; whereas, Ccn4 and Ccn5 showed quite similar patterns. Furthermore, we evaluated the effects of CCN family members on the osteoblastic activities by using recombinant CCN proteins and RNA interference method. Five members of this family displayed positive effects on osteoblast proliferation or differentiation. Of note, CCN3 drastically inhibited the osteoblast activities. Each Ccn specific siRNA could modulate osteoblast activities in a manner expected by the observed effect of respective recombinant CCN protein. In addition, we found that extracellular signal-regulated kinase1/2 and p38 mitogen-activated protein kinase pathways were critically involved in the CCN family member-mediated modification of osteoblast activities. Collectively, all Ccn family members were found to be differentially expressed along with differentiation and therefore could participate in progression of the osteoblast lineage.

TGF-beta signalling in colon carcinogenesis

Colorectal cancer remains the most common cancer and the second leading cause of cancer mortality in Europe. There are a number of pathways that have been implicated in colorectal carcinogenesis, including TGF-beta (TGF-β)/Smad signalling pathway. The TGF-β pathway is involved in several biological processes, including cell proliferation, differentiation, migration and apoptosis. Here we review the role of TGF-β signalling cascade in colorectal carcinogenesis and provide some new molecular insights that may aid efforts towards targeted antitumor therapies.

Transforming growth factor beta-induced reactivation of Epstein-Barr virus involves multiple Smad-binding elements cooperatively activating expression of the latent-lytic switch BZLF1 gene

Transforming growth factor β (TGF-β) physiologically induces Epstein-Barr virus (EBV) lytic infection by activating the expression of EBV's latent-lytic switch BZLF1 gene. Liang et al. (J. Biol. Chem. 277:23345-23357, 2002) previously identified a Smad-binding element (SBE) within the BZLF1 promoter, Zp; however, it accounts for only 20 to 30% of TGF-β-mediated activation of transcription from Zp. Here, we identified additional factors responsible for the rest of this activation. The incubation of EBV-positive MutuI cells with a TGF-β neutralizing antibody or inhibitors of the TGF-β type I receptor (TβRI) or Smad3 eliminated the TGF-β-induced reactivation of EBV. The coexpression of Smad2, Smad3, and Smad4 together with a constitutively active form of TβRI induced 15- to 25-fold transcription from Zp in gastric carcinoma AGS cells. By electrophoretic mobility shift assays, we identified four additional Smad-binding elements, named SBE2 to SBE5. Substitution mutations in individual SBEs reduced Smad-mediated activation of Zp by 20 to 60%; together, these mutations essentially eliminated it. Chromatin immunoprecipitation assays confirmed that Smad4 newly bound the Zp region of the EBV genome following the incubation of MutuI cells with TGF-β. SBE2 overlaps the ZEB-binding ZV silencing element of Zp. Depending upon posttranslational modifications, Smad4 either competed with ZEB1 for binding or formed a complex with ZEB1 on the Zp ZV element in a cell-free assay system. In transiently transfected cells, exogenously expressed ZEB1 inhibited Smad-mediated transcriptional activation from Zp. We conclude that TGF-β induces EBV lytic reactivation via the canonical Smad pathway by activating BZLF1 gene expression through multiple SBEs acting in concert.

TGF-β/BMPs: crucial crossroad in neural autoimmune disorders

Transforming growth factor beta (TGF-β) has a crucial role in the differentiation of ectodermal cells to neural or epidermal precursors. TGF-β and bone morphogenetic protein molecules (BMPs) are involved in many developmental processes, including cell proliferation and differentiation, apoptosis, mitotic arrest and intercellular interactions during morphogenesis. Additionally, the failure of central thymic tolerance mechanisms, leading to T cells with a skewed autoreactive response, is being described as a contributor in inflammatory processes in autoimmune diseases such as multiple sclerosis. Since TGF-β and BMP proteins are crucial for the development of the neural system and the thymus, as well as for the differentiation of T cells, it is essential to further investigate their role in the pathophysiology of this disorder by using references from embryonic experimental research. Available literature in the TGF/BMP signalling cascade, mostly during embryonic development of the nervous system is being reviewed. An attempt is made to further elucidate a potential role of TGF/BMP signalling in the pathophysiology of MS. During demyelination, BMP signaling, through various molecular mechanisms, directs the development of the adult neural stem cell in the astrocyte rather than the oligodendrocyte direction, therefore inhibiting the repair process. Further understanding of the above relationships could lead to the development of potentially efficient therapies for MS in the future.