TGF-beta and the Smad signal transduction pathway

Physiological Functions of the Ubiquitin Ligases Nedd4-1 and Nedd4-2

The Nedd4 family of E3 ubiquitin ligases, consisting of a C2-WW(n)-HECT domain architecture, includes the closely related Nedd4/Nedd4-1 and Nedd4L/Nedd4-2, which play critical roles in human physiology and pathophysiology.This review focuses on the regulation of enzymatic activity of these Nedd4 proteins, as well as on their roles in regulating stability and function of membrane and other signaling proteins, such as ion channels, ion transporters, and growth factor receptors. The diseases caused by impairment of such regulation are discussed, as well as opportunities and challenges for targeting these enzymes for therapy.

The miR-143/145 cluster induced by TGF-β1 suppresses Wilms' tumor 1 expression in cultured human podocytes

Transforming growth factor (TGF)-β1 contributes to podocyte injury in various glomerular diseases, including diabetic kidney disease, probably at least in part by attenuating the expression of Wilms' tumor 1 (WT1). However, the precise mechanisms remain to be defined. We performed miRNA microarray analysis in a human podocyte cell line cultured with TGF-β1 to examine the roles of miRNAs in podocyte damage. The microarray analysis identified miR-143-3p as the miRNA with the greatest increase following exposure to TGF-β1. Quantitative RT-PCR confirmed a significant increase in the miR-143-3p/145-5p cluster in TGF-β1-supplemented cultured podocytes and demonstrated upregulation of miR-143-3p in the glomeruli of mice with type 2 diabetes. Ectopic expression of miR-143-3p and miR-145-5p suppressed WT1 expression in cultured podocytes. Furthermore, inhibition of Smad or mammalian target of rapamycin signaling each partially reversed the TGF-β1-induced increase in miR-143-3p/145-5p and decrease in WT1. In conclusion, TGF-β1 induces expression of miR-143-3p/145-5p in part through Smad and mammalian target of rapamycin pathways, and miR-143-3p/145-5p reduces expression of WT1 in cultured human podocytes. miR-143-3p/145-5p may contribute to TGF-β1-induced podocyte injury.NEW & NOTEWORTHY This study by miRNA microarray analysis demonstrated that miR-143-3p expression was upregulated in cultured human podocytes following exposure to transforming growth factor (TGF)-β1. Furthermore, we report that the miR-143/145 cluster contributes to decreased expression of Wilms' tumor 1, which represents a possible mechanism for podocyte injury induced by TGF-β1. This study is important because it presents a novel mechanism for TGF-β-associated glomerular diseases, including diabetic kidney disease (DKD), and suggests potential therapeutic strategies targeting miR-143-3p/145-5p.

Zearalenone Exposure Triggered Cecal Physical Barrier Injury through the TGF-β1/Smads Signaling Pathway in Weaned Piglets

This study aims to investigate the effects of exposure to different dosages of zearalenone (ZEA) on cecal physical barrier functions and its mechanisms based on the TGF-β1/Smads signaling pathway in weaned piglets. Thirty-two weaned piglets were allotted to four groups and fed a basal diet supplemented with ZEA at 0, 0.15, 1.5, and 3.0 mg/kg, respectively. The results showed that 1.5 and 3.0 mg/kg ZEA damaged cecum morphology and microvilli, and changed distribution and shape of M cells. Moreover, 1.5 and 3.0 mg/kg ZEA decreased numbers of goblet cells, the expressions of TFF3 and tight junction proteins, and inhibited the TGF-β1/Smads signaling pathway. Interestingly, the 0.15 mg/kg ZEA had no significant effect on cecal physical barrier functions but decreased the expressions of Smad3, p-Smad3 and Smad7. Our study suggests that high-dose ZEA exposure impairs cecal physical barrier functions through inhibiting the TGF-β1/Smads signaling pathway, but low-dose ZEA had no significant effect on cecum morphology and integrity through inhibiting the expression of smad7. These findings provide a scientific basis for helping people explore how to reduce the toxicity of ZEA in feeds.

Amygdalin isolated from Amygdalus mongolica protects against hepatic fibrosis in rats

The aim of this research was to investigate the effect of amygdalin on hepatic fibrosis in rats. Amygdalin was purified and identified from the seeds of Amygdalus mongo lica. Sprague Dawley rats in the control and model groups were administered water. Sprague Dawley rats were divided into the low-, middle-, and high-dose amygdalin groups that received 20, 40, and 80 mg kg^-1 amygdalin, respectively. whereas the silymarin group was treated with 50 mg kg^-1 silymarin. The control and model groups were administered water. Liver tissue analysis revealed significantly lower activities of ALT, AST, ALP, SOD, and MDA in the drug-treated groups compared to the model group. Serum analysis revealed significantly lower HYC and C-IV in the middle-dose amygdalin-treated group compared to the model group. The histopathological changes were less severe in the drug-treated groups as observed by the formation of pseudolobuli and decreased collagen fiber deposition. Hepatic fibrosis-related genes were expressed at significantly lower levels in the amygdalin-treated groups than in the model group. Amygdalin from A. mongolica represents a therapeutic candidate for hepatic fibrosis prevention and treatment.

Narasin inhibits tumor metastasis and growth of ERα‑positive breast cancer cells by inactivation of the TGF‑β/SMAD3 and IL‑6/STAT3 signaling pathways

Treatment of human estrogen receptor (ER)-positive breast cancer (ER⁺ BC) using conventional chemotherapy remains a challenge and is often ineffective as a result of tumor metastasis. The present study aimed to investigate the ability of narasin, an ionophore antibiotic, to potentially inhibit tumor metastasis and growth in human ER⁺ BC. Narasin was found to have significant inhibitory abilities on cell proliferation, migration and invasion in ER⁺ BC cell lines MCF-7 and T47D compared with the triple-negative BC cell MDA-MB-231. For the in vivo studies, narasin effectively decreased the number of tumor metastasis nodules, tumor volume and weight without apparent toxicity in human MCF-7 nude mouse left ventricle injection tumor metastasis and xenograft models. Mechanistically, it demonstrated that exposure to TGF-β or IL-6 induced the expression of epithelial-mesenchymal transition (EMT) markers in ER⁺ BC cell lines. On the contrary, narasin dose-dependently reversed EMT by increasing the expression of E-cadherin and decreasing the expression of N-cadherin, vimentin, β-catenin and zinc finger E-box-binding homeobox 1 at the protein and gene expression levels. Gene microarray, molecular docking and western blotting were performed to demonstrate that those protein and gene expression levels are regulated by the inactivation of the TGF-β/phosphorylated (p)-SMAD3 and IL-6/p-STAT3 signaling pathways. Taken together, these findings indicated that narasin may be a promising candidate that can be further optimized for the treatment of human ER⁺ BC.

A Proliferation-Inducing Ligand Regulation in Polymorphonuclear Neutrophils by Panax ginseng

A proliferation-inducing ligand (APRIL) is a member of the tumor necrosis factor superfamily that was first identified as a factor favoring tumorigenesis. APRIL is important fitness and survival factors for B cells and plasma cells in the periphery. Considering this, as well as the quantitative predominance of neutrophils among the peripheral blood leukocytes, we carried out the first study assessing the influence of the transforming growth factor (TGF)-β signaling pathway on APRIL expression in these cells. Furthermore, as the Rb1 ginsenoside is known to exhibit multiple pharmacological activities, we verified if the saponin is capable of modulating the process. The present study shows that TGF-β increased the expression of APRIL and the level of phospho-p38, phospho-Akt(T308), and phospho-Akt(S473) in the cytoplasmic fraction, as well as the expression of Fra1, c-Fos, and c-Jun in the nuclear fraction, of neutrophils. However, exposure of these cells to Rb1 reduced the expression and level of the investigated proteins. No changes were found in the expression of APRIL and the level of p-p38 in the cytoplasmic fraction of neutrophils following the application of Rb1 alone, as well as in the neutrophils incubated first with Rb1 and then with TGF-β, whereas a higher level of phosphorylation was observed for Akt and PI3 kinases in the cells. Moreover, a higher expression of all the studied transcription factors was observed in the nuclear fraction of neutrophils. Based on the observed changes, it may be assumed that the expression of APRIL molecule in TGF-β-induced neutrophils and its regulation by Rb1 are associated with PI3K/AKT signaling pathways and transcription factors Fra-1, Fra-2, c-Jun, and c-Fos. Rb1 appears to be a favorable factor that may be potentially used in the modulation of tumor-promoting APRIL expression.

Indole alkaloids from leaves of Alstonia scholaris (L.) R. Br. protect against emphysema in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Alstonia scholaris (L.) R. Br. (Apocynaceae) is a medicinal plant in China traditionally used to treat pulmonary diseases, including bronchitis, whooping cough, asthma and chronic obstructive pulmonary disease.

AIM OF THE STUDY

To provide experimental data supporting clinical adaptation of total indole alkaloids ( TA) from A. scholaris leaves for treating emphysema.

MATERIALS AND METHODS

An emphysema model was induced by a single intratracheal instillation of porcine pancreatic elastase followed by administration of TA and four main alkaloid components (scholaricine, 19-epischolaricine, vallesamine, and picrinine) for 30 consecutive days. Cytokine levels, histopathological parameters and protein expression in lung tissues were examined.

RESULTS

Administering the TA, picrinine, scholaricine, 19-epischolaricine and vallesamine for 30 days effectively inhibited inflammatory cell accumulation and invasion in the lung tissue and relieved pulmonary tissue injury. Oxygen saturation was enhanced, and interleukin (IL)-1β, monocyte-chemo attractive peptide 1, IL-11, matrix metalloproteinase-12, transforming growth factor-β and vascular endothelial growth factor levels were significantly reduced, likely by suppressing overactivation of alveolar macrophages and pulmonary fibrosis. The elastin content was markedly elevated, and fibronectin was reduced. Bcl-2 expression was significantly increased, and nuclear factor-κB and β-catenin levels were decreased.

CONCLUSIONS

TA can be potentially used as an effective novel drug for pulmonary emphysema and exerts its effects through not only inhibiting inflammation of the airway wall and airflow resistance but also promoting lung elastic recoil and protease/anti-protease balance.

High-dose TGF-β1 degrades human nucleus pulposus cells via ALK1-Smad1/5/8 activation

Transforming growth factor β1 (TGF-β1) can promote the proliferation and differentiation of intervertebral disc cells and participates in its repair process. However, whether TGF-β1 engages in the process of disc degeneration has not yet been fully elucidated. The present study aimed to investigate the function of high-dose TGF-β1 on the metabolism of nucleus pulposus cells (NPCs). TGF-β1 levels in human degenerative intervertebral disc tissues and tumor necrosis factor (TNF)-α-induced degenerative NPCs were analyzed. Furthermore, NPCs were treated with TGF-β1 and inhibitors of TGF-β1 receptors [ALK tyrosine kinase receptor (ALK) 1 and ALK5] to determine the effect of the receptors in the mediation of NPC degeneration. The NPC state was determined by the components of secretory collagen I/II, tissue inhibitor of metalloproteinase-3 (TIMP-3) and matrix metalloproteinase (MMP)-13. The mRNA expression of Smad1/2/3/5/8, the downstream gene of TGF-β1 mediated by ALK, was also measured. Results showed that TGF-β1 and ALK1 were positively associated with the degree of degeneration of NP or NPCs in vitro, but negatively associated with ALK5. Furthermore, high-doses of TGF-β1 suppressed collagen II, but enhanced collagen I, TIMP-3, MMP-13, ALK1/5 and Smad1/2/3/5/8 expression. ALK5 inhibition induced the suppression of Smad2/3 and aggravated high-dose TGF-β1-induced NPC degeneration, as shown by the reduction in collagen II and increase in collagen I, TIMP-3 and MMP-13. By contrast, ALK1 inhibition resulted in Smad1/5/8 suppression and alleviated high-dose TGF-β1-induced NPC degeneration. Taken together, it was concluded that high-doses of TGF-β1 contributed to the degeneration of NPCs via the upregulation of ALK1 and Smad1/5/8.

Bone morphogenetic protein 2 (BMP2) mediates spermatogenesis in Chinese mitten crab Eriocheir sinensis by regulating kinesin motor KIFC1 expression

The TGF-beta superfamily is widely involved in cell events such as cell division and differentiation, while bone morphogenetic proteins (BMPs) belong to one of the subgroups. Their functions in crustacean spermatogenesis are still unknown. In this study, we first identified the bone morphogenetic protein 2 (bmp2) from Eriocheir sinensis (E. sinensis) testis. The es-BMP2 shows high expression in E. sinensis testis. We found that es-BMP2 is expressed in spermatids. The successfully knockdown of es-BMP2 through in vivo RNAi are used for functional analysis. Compared with the control group, the proportion of abnormal nuclear cup morphology in mature spermatozoa increased significantly after es-bmp2 RNAi, suggesting that es-BMP2 plays an important role in mature sperm morphogenesis. Immunofluorescence results confirm this finding. In order to study the specific mechanism of es-BMP2 involved in spermiogenesis, we tested kinesin-14 KIFC1, which functions in the nucleus formation of spermatozoa in E. sinensis. The results showed that knockdown of es-BMP2 caused a significant decrease of es-KIFC1 expression. We further performed es-bmp2 knockdown in vitro in primary cultured testis cells. es-KIFC1 expression was significantly reduced after es-bmp2 RNAi. The above results indicate that es-BMP2 participates in maintaining the spermiogenesis of E. sinensis by regulating es-KIFC1 expression.

Activation of Nrf2/AREs-mediated antioxidant signalling, and suppression of profibrotic TGF-β1/Smad3 pathway: a promising therapeutic strategy for hepatic fibrosis - A review

Hepatic fibrosis (HF) is a wound-healing response that occurs during chronic liver injury and features by an excessive accumulation of extracellular matrix (ECM) components. Activation of hepatic stellate cell (HSC), the leading effector in HF, is responsible for overproduction of ECM. It has been documented that transforming growth factor-β1 (TGF-β1) stimulates superfluous accumulation of ECM and triggers HSCs activation mainly via canonical Smad-dependent pathway. Also, the pro-fibrogenic TGF-β1 is correlated with generation of reactive oxygen species (ROS) and inhibition of antioxidant mechanisms. Moreover, involvement of oxidative stress (OS) can be clearly elucidated as a fundamental event in liver fibrogenesis. Nuclear factor erythroid 2-related factor 2-antioxidant response elements (Nrf2-AREs) pathway, a group of OS-mediated transcription factors with diverse downstream targets, is associated with the induction of diverse detoxifying enzymes and the most pivotal endogenous antioxidative system. More specifically, Nrf2-AREs pathway has recently assigned as a new therapeutic target for cure of HF. The overall goal of this review will focus on recent findings about activation of Nrf2-AREs-mediated antioxidant and suppression of profibrotic TGF-β1/Smad3 pathway in the liver, providing an overview of recent advances in transcriptional repressors that dislocated during HF formation, and highlighting possible novel therapeutic targets for liver fibrosis.

The role of miR-431-5p in regulating pulmonary surfactant expression in vitro

Background

Pulmonary surfactant is the complex mixture of lipid and protein that covers the alveolar surface. Pulmonary surfactant deficiency is one of the main causes of neonatal respiratory distress. Recent studies showed that miRNA plays an important role in lung development, but research into miR-431 regulation of pulmonary surfactant are sparse. In this study, we explored the regulatory role of miR-431-5p in the expression of pulmonary surfactant and identified its potential target gene, Smad4.

Methods

The bioinformatics tool TargetScan was used to predict the targets of miR-431. The expression of miR-431-5p was achieved via transfection of miR-431-5p mimics, an miR-431-5p inhibitor and corresponding negative control. The level of miR-431-5p was determined using quantitative real-time PCR. The CCK8 assay was conducted to confirm cell growth 12 h after transfection with miR-431-5p mimics, inhibitor or NC. Smad4 and surfactant-associated proteins in A549 were analyzed using western blot and quantitative real-time PCR.

Results

Smad4 was validated as a target of miR-431 in A549 cells. Overexpression of miR-431 accelerated A549 proliferation and inhibited A549 apoptosis. The mRNA and protein levels for the surfactant proteins (SP-A, SP-B, SP-C and SP-D) were found to be differentially expressed in A549 cells over- or under-expressing miR-431-5p.

Conclusion

Our results show that miR-431-5p is critical for pulmonary surfactant expression and that its regulation is closely related to the TGF-β/Smad4 pathway. These results will help us to study the pathophysiological mechanism of lung developmental diseases.

Recent Developments in Breast Muscle Myopathies Associated with Growth in Poultry

The functional unit in skeletal muscle is the multinucleated myofiber, which is composed of parallel arrays of microfibrils. The myofiber and sarco-mere structure of skeletal muscle are established during embryogenesis, when mononuclear myoblast cells fuse to form multinucleated myotubes and develop into muscle fibers. With the myoblasts permanently unable to enter a proliferative state again after they fuse to form the multinucleated myotube, postnatal myofiber growth, muscle homeostasis, and myofiber regeneration are dependent on a myogenic stem cell, the satellite cell. Because the satellite cell is a partially differentiated stem cell controlling the state of skeletal muscle structure throughout the life of the bird, it can impact muscle development and structure, growth, and regeneration and, subsequently, meat quality. When myofibers are damaged, muscle repair is dependent on the satellite cells. Regenerated myofibers after the repair process should be similar to the original muscle fiber. Despite significant improvements in meat-type birds, degenerative myopathies have arisen. In many of these degenerative breast muscle myopathies, like Wooden Breast, satellite cell–mediated regeneration of muscle is suppressed. Thus, the biological function of avian myogenic satellite cells and their influence on cellular mechanisms affecting breast muscle development and growth, function during degenerative myopathies, and meat quality are discussed.

JNK regulates muscle remodeling via myostatin/SMAD inhibition

Skeletal muscle has a remarkable plasticity to adapt and remodel in response to environmental cues, such as physical exercise. Endurance exercise stimulates improvements in muscle oxidative capacity, while resistance exercise induces muscle growth. Here we show that the c-Jun N-terminal kinase (JNK) is a molecular switch that when active, stimulates muscle fibers to grow, resulting in increased muscle mass. Conversely, when muscle JNK activation is suppressed, an alternative remodeling program is initiated, resulting in smaller, more oxidative muscle fibers, and enhanced aerobic fitness. When muscle is exposed to mechanical stress, JNK initiates muscle growth via phosphorylation of the transcription factor, SMAD2, at specific linker region residues leading to inhibition of the growth suppressor, myostatin. In human skeletal muscle, this JNK/SMAD signaling axis is activated by resistance exercise, but not endurance exercise. We conclude that JNK acts as a key mediator of muscle remodeling during exercise via regulation of myostatin/SMAD signaling.

Activation of Activin receptor-like kinases curbs mucosal inflammation and proliferation in chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a widespread disease causing obstruction of the nasal cavity. Its cause remains unclear. The transforming growth-factor beta (TGF-β) superfamily and their receptors, termed Activin receptor-like kinases (ALKs), have recently been suggested to play a role in local airway inflammation, but have so far not been evaluated in human nasal epithelial cells (HNECs) from CRSwNP patients. We demonstrated that ALK1–7 were expressed in the nasal polyp epithelium, and the expression of ALK1-6 was markedly elevated in polyps compared to nasal mucosa from healthy controls. Stimulation with the ALK ligand TGF-β1 decreased Ki67 expression in HNECs from CRSwNP patients, not evident in controls. Likewise, TGF-β1, Activin A and Activin B, all ALK ligands, decreased IL-8 release and Activin A and Activin B reduced ICAM1 expression on HNECs from CRSwNP patients, not seen in controls. Pre-stimulation with TGF-β1, Activin A, BMP4 and Activin B attenuated a TNF-α-induced ICAM1 upregulation on HNECs of CRSwNP. No effect was evident in controls. In conclusion, an increased expression of ALK1-6 was found on polyp epithelial cells and ligand stimulation appeared to reduce proliferation and local inflammation in polyps.

An Update on the Therapeutic Potential of Stem Cells

The seeming setbacks noted for stem cells underscore the need for experimental studies for safe and efficacious application to patients. Both clinical and experimental researchers have gained valuable knowledge on the characteristics of stem cells, and their behavior in different microenvironment. This introductory chapter focuses on adult mesenchymal stem cells (MSCs) based on the predominance in the clinic. MSCs can be influenced by inflammatory mediators to exert immune suppressive properties, commonly referred to as "licensing." Interestingly, while there are questions if other stem cells can be delivered across allogeneic barrier, there is no question on the ability of MSCs to provide this benefit. This property has been a great advantage since MSCs could be available for immediate application as "off-the-shelf" stem cells for several disorders, tissue repair and gene/drug delivery. Despite the benefit of MSCs, it is imperative that research continues with the various types of stem cells. The method needed to isolate these cells is outlined in this book. In parallel, safety studies are needed; particularly links to oncogenic event. In summary, this introductory chapter discusses several potential areas that need to be addressed for safe and efficient delivery of stem cells, and argue for the incorporation of microenvironmental factors in the studies. The method described in this chapter could be extrapolated to the field of chimeric antigen receptor T-cells (CAR-T). This will require application to stem cell hierarchy of memory T-cells.

Transforming growth factor β-induced epithelial to mesenchymal transition requires the Ste20-like kinase SLK independently of its catalytic activity

Invasion can be stimulated in vitro using the soluble ligand transforming growth factor-β (TGFβ) to induce a process called epithelial-to-mesenchymal transition (EMT) characterized by cell-cell junction breakdown and an invasive phenotype. We have previously demonstrated a role for Ste20-like kinase SLK cell migration and invasion. Here we show that SLK depletion in NMuMG mammary epithelial cells significantly impairs their TGFβ-induced migration and invasion. Immunofluorescence studies show that a fraction of SLK localizes to E-cadherin-positive adherens junction and that SLK impairs the breakdown of cell-cell contacts. We find that SLK-depleted cultures express significantly lower levels of vimentin protein as well as Snai1 and E-cadherin mRNA levels following TGF-β treatment. Surprisingly, our data show that SLK depletion does not affect the activation and nuclear translocation of Smad3. Furthermore, we show that expression of a dominant negative kinase does not impair tight junction breakdown and rescues Snai1 mRNA expression levels. Together these data suggest that SLK plays a novel role in TGFβ-induced EMT, independent of Smads, in a kinase activity-independent manner.

MiR-490-5p Suppresses Cell Proliferation and Invasion by Targeting BUB1 in Hepatocellular Carcinoma Cells

OBJECTIVE

To verify that miR-490-5p could influence hepatocellular carcinoma (HCC) cells' proliferation, invasion, cycle, and apoptosis by targeting BUB1.

METHODS

Quantitative real time-PCR (QRT-PCR) was used to determine the miR-490-5p expression. Immunohistochemistry, qRT-PCR, and Western blot were employed to detect BUB1 and transforming growth factor-beta (TGFβ/Smad) signaling-related proteins expression in hepatic tissues and cells. The luciferase assay was used to confirm the targeting relationship between miR-490-5p and BUB1. The Cell Counting Kit-8, colony formation, Transwell invasion, scratch healing assays, and flow cytometry analysis were conducted to evaluate HCC cells proliferation, invasion, migration, and apoptosis alteration after transfection.

RESULTS

In HCC tissues and cells, lower expression of miR-490-5p was detected, while BUB1 was overexpressed than controls. The upregulation of miR-490-5p inhibited BUB1 expression and the overexpression of miR-490-5p or the under-expression of BUB1 inhibited HCC cells proliferation, migration, invasion, and increased the apoptosis rate.

CONCLUSION

MiR-490-5p could regulate TGFβ/Smad signaling pathways by inhibiting BUB1, which could then inhibit HCC cells proliferation, invasion, and migration as well as decrease cell viability and increase apoptosis.

Dibutyryl-cAMP attenuates pulmonary fibrosis by blocking myofibroblast differentiation via PKA/CREB/CBP signaling in rats with silicosis

BACKGROUND

Myofibroblasts play a major role in the synthesis of extracellular matrix (ECM) and the stimulation of these cells is thought to play an important role in the development of silicosis. The present study was undertaken to investigate the anti-fibrotic effects of dibutyryl-cAMP (db-cAMP) on rats induced by silica.

METHODS

A HOPE MED 8050 exposure control apparatus was used to create the silicosis model. Rats were randomly divided into 4 groups: 1)controls for 16 w; 2)silicosis for 16 w; 3)db-cAMP pre-treatment; 4) db-cAMP post-treatment. Rat pulmonary fibroblasts were cultured in vitro and divided into 4 groups as follows: 1) controls; 2) 10^-7mol/L angiotensin II (Ang II); 3) Ang II +10^-4 mol/L db-cAMP; and 4) Ang II + db-cAMP+ 10^-6 mol/L H89. Hematoxylin-eosin (HE), Van Gieson staining and immunohistochemistry (IHC) were performed to observe the histomorphology of lung tissue. The levels of cAMP were detected by enzyme immunoassay. Double-labeling for α-SMA with Gαi3, protein kinase A (PKA), phosphorylated cAMP-response element-binding protein (p-CREB), and p-Smad2/3 was identified by immunofluorescence staining. Protein levels were detected by Western blot analysis. The interaction between CREB-binding protein (CBP) and Smad2/3 and p-CREB were measured by co-immunoprecipitation (Co-IP).

RESULTS

Db-cAMP treatment reduced the number and size of silicosis nodules, inhibited myofibroblast differentiation, and extracellular matrix deposition in vitro and in vivo. In addition, db-cAMP regulated Gαs protein and inhibited expression of Gαi protein, which increased endogenous cAMP. Db-cAMP increased phosphorylated cAMP-response element-binding protein (p-CREB) via protein kinase A (PKA) signaling, and decreased nuclear p-Smad2/3 binding with CREB binding protein (CBP), which reduced activation of p-Smads in fibroblasts induced by Ang II.

CONCLUSIONS

This study showed an anti-silicotic effect of db-cAMP that was mediated via PKA/p-CREB/CBP signaling. Furthermore, the findings offer novel insight into the potential use of cAMP signaling for therapeutic strategies to treat silicosis.

Binding and biologic characterization of recombinant human serum albumin-eTGFBR2 fusion protein expressed in CHO cells

Transforming growth factor-β1 (TGF-β1) signaling is involved in cell metabolism, growth, differentiation, carcinoma invasion and fibrosis development, which suggests TGF-β1 can be treated as a therapeutic target extensively. Because TGF-β1 receptor type α(TGFBR2) is the directed and essential mediator for TGF-β1 signals, the extracellular domain of TGFBR2 (eTGFBR2), binding partner for TGF-β1, has been produced in a series of expression systems to inhibit TGF-β1 signaling. However, eTGFBR2 is unstable with a short half-life predominantly because of enzymatic degradation and kidney clearance. In this study, a fusion protein consisting of human eTGFBR2 fused at the C-terminal of human serum albumin (HSA) was stably and highly expressed in Chinese Hamster Ovary (CHO) cells. The high and stable expression sub-clones with Ig kappa signal peptide were selected by Western blot analysis and used for suspension culture. After fed-batch culture over 8 d, the expression level of HSA-eTGFBR2 reached 180 mg/L. The fusion protein was then purified from culture medium using a 2-step chromatographic procedure that resulted in 39% recovery rate. The TGF-β1 binding assay revealed that HSA-eTGFBR2 could bind to TGF-β1 with the affinity constant (K_D of 1.42 × 10^-8 M) as determined by the ForteBio Octet System. In addition, our data suggested that HSA-eTGFBR2 exhibited a TGF-β1 neutralizing activity and maintained a long-term activity more than eTGFBR2. It concluded that the overexpressing CHO cell line supplied sufficient recombinant human HSA-eTGFBR2 for further research and other applications.

TGF-β1 protects intestinal integrity and influences Smads and MAPK signal pathways in IPEC-J2 after TNF-α challenge

The aim of this study was to investigate the protective effects of TGF-β1 on intestinal epithelial barrier, as well as canonical Smad and MAPK signal pathways involved in these protection processes by a IPEC-J2 model stimulated with TNF-α. IPEC-J2 monolayers were treated without or with TNF-α in the absence or presence of TGF-β1. The results showed that TGF-β1 pretreatment ameliorated TNF-α-induced intestinal epithelial barrier disturbances as indicated by decrease of transepithelial electrical resistance (TER) and increase of paracellular permeability. TGF-β1 also dramatically alleviated TNF-α-induced alteration of TJ proteins ZO-1 and occludin. Moreover, TGF-β1 pretreatment increased TβRII protein expression in IPEC-J2 monolayers challenged with TNF-α. In addition, a significant increase of Smad4 and Smad7 mRNA was also observed in the TGF-β1 pretreatment after TNF-α challenge compared with the control group. Furthermore, TGF-β1 pretreatment enhanced smad2 protein activation. These results indicated that the canonical Smad signaling pathway was activated by TGF-β1 pretreatment. Finally, TGF-β1 pretreatment decreased the ratios of the phosphorylated to total JNK and p38 (p-JNK/JNK and p-p38/p38) and increased the ratio of ERK (p-ERK/ERK). Anti-TGF-β1 Abs reduced these TGF-β1 effects. These results indicated that TGF-β1 protects intestinal integrity and influences Smad and MAPK signal pathways in IPEC-J2 after TNF-α challenge.

Hsa-miR-590-5p Interaction with SMAD3 Transcript Supports Its Regulatory Effect on The TGFβ Signaling Pathway

OBJECTIVE

SMAD proteins are the core players of the transforming growth factor-beta (TGFβ) signaling pathway, a pathway which is involved in cell proliferation, differentiation and migration. On the other hand, hsa-miRNA-590-5p (miR-590-5p) is known to have a negative regulatory effect on TGFβ signaling pathway receptors. Since, RNAhybrid analy- sis suggested SMAD3 as a bona fide target gene for miR-590, we intended to investigate the effect of miR-590-5p on SMAD3 transcription.

MATERIALS AND METHODS

In this experimental study, miR-590-5p was overexpressed in different cell lines and its increased expression was detected through quantitative reverse transcription-polymerase chain reaction (RT-qPCR). Western blot analysis was then used to investigate the effect of miR-590-5p overexpression on SMAD3 protein level. Next, the direct interaction of miR-590-5p with the 3´-UTR sequence of SMAD3 transcript was investigated using the dual luciferase assay. Finally, flow cytometery was used to inves- tigate the effect of miR-590-5p overexpression on cell cycle progression in HeLa and SW480 cell lines.

RESULTS

miR-590-5p was overexpressed in the SW480 cell line and its overexpression resulted in significant reduction of the SMAD3 protein level. Consistently, direct interaction of miR-590-5p with 3´-UTR sequence of SMAD3 was detected. Finally, miR-590-5p over- expression did not show a significant effect on cell cycle progression of Hela and SW480 cell lines.

CONCLUSION

Consistent with previous reports about the negative regulatory effect of miR-590 on TGFβ receptors, our data suggest that miR-590-5p also attenuates the TGFβ signaling pathway through down-regulation of SMAD3.

The adhesion molecule PECAM-1 enhances the TGF-β-mediated inhibition of T cell function

Transforming growth factor-β (TGF-β) is an immunosuppressive cytokine that inhibits the proinflammatory functions of T cells, and it is a major factor in abrogating T cell activity against tumors. Canonical TGF-β signaling results in the activation of Smad proteins, which are transcription factors that regulate target gene expression. We found that the cell surface molecule platelet endothelial cell adhesion molecule-1 (PECAM-1) facilitated noncanonical (Smad-independent) TGF-β signaling in T cells. Subcutaneously injected tumor cells that are dependent on TGF-β-mediated suppression of immunity for growth grew more slowly in PECAM-1(-/-) mice than in their wild-type counterparts. T cells isolated from PECAM-1(-/-) mice demonstrated relative insensitivity to the TGF-β-dependent inhibition of interferon-γ (IFN-γ) production, granzyme B synthesis, and cellular proliferation. Similarly, human T cells lacking PECAM-1 demonstrated decreased sensitivity to TGF-β in a manner that was partially restored by reexpression of PECAM-1. Co-incubation of T cells with TGF-β and a T cell-activating antibody resulted in PECAM-1 phosphorylation on an immunoreceptor tyrosine-based inhibitory motif (ITIM) and the recruitment of the inhibitory Src homology 2 (SH2) domain-containing tyrosine phosphatase-2 (SHP-2). Such conditions also induced the colocalization of PECAM-1 with the TGF-β receptor complex as identified by coimmunoprecipitation, confocal microscopy, and proximity ligation assays. These studies indicate a role for PECAM-1 in enhancing the inhibitory functions of TGF-β in T cells and suggest that therapeutic targeting of the PECAM-1-TGF-β inhibitory axis represents a means to overcome TGF-β-dependent immunosuppression within the tumor microenvironment.

Peroxiredoxin 5 Protects TGF-β Induced Fibrosis by Inhibiting Stat3 Activation in Rat Kidney Interstitial Fibroblast Cells

Renal fibrosis is a common final pathway of end-stage kidney disease which is induced by aberrant accumulation of myofibroblasts. This process is triggered by reactive oxygen species (ROS) and proinflammatory cytokines generated by various source of injured kidney cells. Peroxiredoxin 5 (Prdx5) is a thiol-dependent peroxidase that reduces oxidative stress by catalyzing intramolecular disulfide bonds. Along with its antioxidant effects, expression level of Prdx5 also was involved in inflammatory regulation by immune stimuli. However, the physiological effects and the underlying mechanisms of Prdx5 in renal fibrosis have not been fully characterized. Sprague-Dawley rats were subjected to unilateral ureteral obstruction (UUO) for 1 or 7 days. For the in vitro model, NRK49F cells, a rat kidney interstitial fibroblast cell lines, were treated with transforming growth factor β (TGF-β) for 0, 1, 3, or 5 days. To access the involvement of its peroxidase activity in TGF-β induced renal fibrosis, wild type Prdx5 (WT) and double mutant Prdx5 (DM), converted two active site cysteines at Cys 48 and Cys 152 residue to serine, were transiently expressed in NRK49F cells. The protein expression of Prdx5 was reduced in UUO kidneys. Upregulation of fibrotic markers, such as fibronectin and alpha-smooth muscle actin (α-SMA), declined at 5 days in time point of higher Prdx5 expression in TGF-β treated NRK49F cells. The overexpression of wild type Prdx5 by transient transfection in NRK49F cells attenuated the TGF-β induced upregulation of fibronectin and α-SMA. On the other hand, the transient transfection of double mutant Prdx5 did not prevent the activation of fibrotic markers. Overexpression of Prdx5 also suppressed the TGF-β induced upregulation of Stat3 phosphorylation, while phosphorylation of Smad 2/3 was unchanged. In conclusion, Prdx5 protects TGF-β induced fibrosis in NRK49F cells by modulating Stat3 activation in a peroxidase activity dependent manner.

Phenylethanol Glycosides from Cistanche tubulosa Suppress Hepatic Stellate Cell Activation and Block the Conduction of Signaling Pathways in TGF-β1/smad as Potential Anti-Hepatic Fibrosis Agents

Cistanche tubulosa is a traditional Chinese herbal medicine widely used for regulating immunity and phenylethanol glycosides (CPhGs) are among the primary components responsible for this activity. Previous studies have indicated the preventive and therapeutic effects of CPhGs on bovine serum albumin (BSA)-induced hepatic fibrosis in rats. The aim of the study was to evaluate the anti-hepatic fibrosis effect of CPhGs and the monomers echinacoside and acteoside by inhibiting hepatic stellate cell (HSC) activation, blocking the conduction of signaling pathways in transforming growth factor-β1 (TGF-β1)/smad, and determine their in vitro hepatoprotective activity. HSC proliferation was obviously inhibited after treatment with CPhGs (100, 50 μg/mL)/echinacoside (500, 250, 125 μg/mL)/acteoside (6, 3 μg/mL), with IC50 values of 119.125, 520.345 and 6.999 μg/mL, respectively, in the MTT assay. Different concentrations of CPhGs/echinacoside/acteoside did not affect the cellular toxicity on HSC according to lactate dehydrogenase (LDH) measurements. Different concentrations of CPhGs/echinacoside/acteoside increased the mRNA level and protein expression of smad7, and decreased the mRNA levels of smad2, smad3 and the protein expression of smad2, phospho-smad2 (p-smad2), smad3, phospho-smad3 (p-smad3) in HSC. In summary, these results demonstrate that CPhGs/echinacoside/acteoside can block the conduction of the signaling pathways in TGF-β1/smad, and inhibit the activation of HSC, suggesting that C. tubulosa may thus be a potential herbal medicine for the treatment of liver fibrosis.

Putative hormone with anti-obesogenic and insulin-sensitizing effect

It was confirmed that bone morphogenetic protein-9 (BMP-9), like insulin, improves glycemia in diabetic mice and regulates glucose metabolism in hepatocytes, which is why it is proposed as a candidate for the hepatic insulin-sensitizing substance (HISS). Regarding the fact that BMP-9 has a signaling pathway similar to other BMPs as well as insulin, it is expected that BMP-9 would also have certain effects on the liver. In our 2011 hypothesis, we aimed towards BMP-9 as a possible "hepatic insulin-sensitizing substance" (HISS) and in this article, we provide further evidence, derived from existing studies, suggesting that this putative hormone might in fact be none other than BMP-9.

Akbu-LAAO exhibits potent anti-tumor activity to HepG2 cells partially through produced H2O2 via TGF-β signal pathway

Previously, we characterized the biological properties of Akbu-LAAO, a novel L-amino acid oxidase from Agkistrodon blomhoffii ussurensis snake venom (SV). Current work investigated its in vitro anti-tumor activity and underlying mechanism on HepG2 cells. Akbu-LAAO inhibited HepG2 growth time and dose-dependently with an IC50 of ~38.82 μg/mL. It could induce the apoptosis of HepG2 cells. Akbu-LAAO exhibited cytotoxicity by inhibiting growth and inducing apoptosis of HepG2 as it showed no effect on its cell cycle. The inhibition of Akbu-LAAO to HepG2 growth partially relied on enzymatic-released H2O2 as catalase only partially antagonized this effect. cDNA microarray results indicated TGF-β signaling pathway was linked to the cytotoxicity of Akbu-LAAO on HepG2. TGF-β pathway related molecules CYR61, p53, GDF15, TOB1, BTG2, BMP2, BMP6, SMAD9, JUN, JUNB, LOX, CCND1, CDK6, GADD45A, CDKN1A were deregulated in HepG2 following Akbu-LAAO stimulation. The presence of catalase only slightly restored the mRNA changes induced by Akbu-LAAO for differentially expressed genes. Meanwhile, LDN-193189, a TGF-β pathway inhibitor reduced Akbu-LAAO cytotoxicity on HepG2. Collectively, we reported, for the first time, SV-LAAO showed anti-tumor cell activity via TGF-β pathway. It provides new insight of SV-LAAO exhibiting anti-tumor effect via a novel signaling pathway.

The footprint of TGF-β in airway remodeling of the mustard lung

Mustard lung is a major pulmonary complication in individuals exposed to sulfur mustard (SM) gas during the Iran-Iraq war. It shares common pathological and clinical features with some chronic inflammatory lung disorders, particularly chronic obstructive pulmonary disease (COPD). Airway remodeling, which is one of the main causes of lung dysfunction and the dominant phenomenon of chronic pulmonary diseases, is seen in the mustard lung. Among all mediators involved in the remodeling process, the transforming growth factor (TGF)-β plays a pivotal role in lung fibrosis and consequently in the airway remodeling. Regarding the high levels of this mediator detected in mustard lung patients, in the present study, we have discussed the possible roles of TGF-β in airway remodeling (including epithelial layer damage, subepithelial fibrosis and angiogenesis). Finally, based on TGF-β targeting, we have reviewed new airway remodeling therapeutic approaches.

Genome-wide Mechanosensitive MicroRNA (MechanomiR) Screen Uncovers Dysregulation of Their Regulatory Networks in the mdm Mouse Model of Muscular Dystrophy

Muscular dystrophies (MDs) are a heterogeneous group of genetic and neuromuscular disorders, which result in severe loss of motor ability and skeletal muscle mass and function. Aberrant mechanotransduction and dysregulated-microRNA pathways are often associated with the progression of MD. Here, we hypothesized that dysregulation of mechanosensitive microRNAs (mechanomiRs) in dystrophic skeletal muscle plays a major role in the progression of MD. To test our hypothesis, we performed a genome-wide expression profile of anisotropically regulated mechanomiRs and bioinformatically analyzed their target gene networks. We assessed their functional roles in the advancement of MD using diaphragm muscles from mdm (MD with myositis) mice, an animal model of human tibial MD (titinopathy), and their wild-type littermates. We were able to show that ex vivo anisotropic mechanical stretch significantly alters the miRNA expression profile in diaphragm muscles from WT and mdm mice; as a result, some of the genes associated with MDs are dysregulated in mdm mice due to differential regulation of a distinct set of mechanomiRs. Interestingly, we found a contrasting expression pattern of the highly expressed let-7 family mechanomiRs, let-7e-5p and miR-98-5p, and their target genes associated with the extracellular matrix and TGF-β pathways, respectively, between WT and mdm mice. Gain- and loss-of-function analysis of let-7e-5p in myocytes isolated from the diaphragms of WT and mdm mice confirmed Col1a1, Col1a2, Col3a1, Col24a1, Col27a1, Itga1, Itga4, Scd1, and Thbs1 as target genes of let-7e-5p. Furthermore, we found that miR-98 negatively regulates myoblast differentiation. Our study therefore introduces additional biological players in the regulation of skeletal muscle structure and myogenesis that may contribute to unexplained disorders of MD.

TCR signaling intensity controls CD8+ T cell responsiveness to TGF-β

DGK-ζ is a negative regulator of TCR signaling that causes degradation of the second messenger DAG, terminating DAG-mediated activation of Ras and PKCθ. Cytotoxic T cells deficient in DGK-ζ demonstrate enhanced effector functions in vitro and antitumor activity in vivo, perhaps because of insensitivity to inhibitory cytokines. We sought to determine whether the enhanced responsiveness of DGK-ζ-deficient T cells renders them insensitive to the inhibitory cytokine TGF-β and to determine how the loss of DGK-ζ facilitates this insensitivity. We identified decreased transcriptional and functional responses to TGF-β in CD8(+) DGK-ζ(-/-) T cells but preserved TGF-β-mediated conversion of naïve DGK-ζ(-/-) CD4(+) T cells to a regulatory T cell phenotype. Decreased CD8(+) T cell responsiveness to TGF-β did not result from impaired canonical TGF-β signal transduction, because similar levels of TGF-β-R and intracellular Smad components were identified in WT and DGK-ζ(-/-) CD8(+) T cells, and TGF-β-mediated activation of Smad2 was unchanged. Instead, an enhanced TCR signal strength was responsible for TGF-β insensitivity, because (i) loss of DGK-ζ conferred resistance to TGF-β-mediated inhibition of Erk phosphorylation, (ii) TGF-β insensitivity could be recapitulated by exogenous addition of the DAG analog PMA, and (iii) TGF-β sensitivity could be observed in DGK-ζ-deficient T cells at limiting dilutions of TCR stimulation. These data indicate that enhanced TCR signal transduction in the absence of DGK-ζ makes T cells relatively insensitive to TGF-β, in a manner independent of Smads, a finding with practical implications in the development of immunotherapies that target TGF-β.

Cyclic nucleotide signalling in kidney fibrosis

Kidney fibrosis is an important factor for the progression of kidney diseases, e.g., diabetes mellitus induced kidney failure, glomerulosclerosis and nephritis resulting in chronic kidney disease or end-stage renal disease. Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were implicated to suppress several of the above mentioned renal diseases. In this review article, identified effects and mechanisms of cGMP and cAMP regarding renal fibrosis are summarized. These mechanisms include several signalling pathways of nitric oxide/ANP/guanylyl cyclases/cGMP-dependent protein kinase and cAMP/Epac/adenylyl cyclases/cAMP-dependent protein kinase. Furthermore, diverse possible drugs activating these pathways are discussed. From these diverse mechanisms it is expected that new pharmacological treatments will evolve for the therapy or even prevention of kidney failure.

Non-histone protein methylation as a regulator of cellular signalling and function

Methylation of Lys and Arg residues on non-histone proteins has emerged as a prevalent post-translational modification and as an important regulator of cellular signal transduction mediated by the MAPK, WNT, BMP, Hippo and JAK-STAT signalling pathways. Crosstalk between methylation and other types of post-translational modifications, and between histone and non-histone protein methylation frequently occurs and affects cellular functions such as chromatin remodelling, gene transcription, protein synthesis, signal transduction and DNA repair. With recent advances in proteomic techniques, in particular mass spectrometry, the stage is now set to decode the methylproteome and define its functions in health and disease.

Developmental changes of TGF-β1 and Smads signaling pathway in intestinal adaption of weaned pigs

Weaning stress caused marked changes in intestinal structure and function. Transforming growth factor-β1 (TGF-β1) and canonical Smads signaling pathway are suspected to play an important regulatory role in post-weaning adaptation of the small intestine. In the present study, the intestinal morphology and permeability, developmental expressions of tight junction proteins and TGF-β1 in the intestine of piglets during the 2 weeks after weaning were assessed. The expressions of TGF-β receptor I/II (TβRI, TβRII), smad2/3, smad4 and smad7 were determined to investigate whether canonical smads signaling pathways were involved in early weaning adaption process. The results showed that a shorter villus and deeper crypt were observed on d 3 and d 7 postweaning and intestinal morphology recovered to preweaning values on d 14 postweaning. Early weaning increased (P<0.05) plasma level of diamine oxidase (DAO) and decreased DAO activities (P<0.05) in intestinal mucosa on d 3 and d 7 post-weaning. Compared with the pre-weaning stage (d 0), tight junction proteins level of occludin and claudin-1 were reduced (P<0.05) on d 3, 7 and 14 post-weaning, and ZO-1 protein was reduced (P<0.05) on d 3 and d 7 post-weaning. An increase (P<0.05) of TGF-β1 in intestinal mucosa was observed on d 3 and d 7 and then level down on d 14 post-weaning. Although there was an increase (P<0.05) of TβR II protein expression in the intestinal mucosa on d3 and d 7, no significant increase of mRNA of TβRI, TβRII, smad2/3, smad4 and smad7 was observed during postweaning. The results indicated that TGF-β1 was associated with the restoration of intestinal morphology and barrier function following weaning stress. The increased intestinal endogenous TGF-β1 didn't activate the canonical Smads signaling pathway.

Zinc oxide influences mitogen-activated protein kinase and TGF-β1 signaling pathways, and enhances intestinal barrier integrity in weaned pigs

Weaning is the most significant event in the life of pigs and is always related with intestinal disruption. Although it is well known that zinc oxide (ZnO) exerts beneficial effects on the intestinal barrier, the mechanisms underlying these effects have not yet been fully elucidated. We examined whether ZnO protects the intestinal barrier via mitogen-activated protein kinases and TGF-β1 signaling pathways. Twelve barrows weaned at 21 d of age were randomly assigned to two treatments (0 verus 2200 mg Zn/kg from ZnO) for 1 wk. The results showed that supplementation with ZnO increased daily gain and feed intake, and decreased postweaning scour scores. ZnO improved intestinal morphology, as indicated by increased villus height and villus height:crypt depth ratio, and intestinal barrier function, indicated by increased transepithelial electrical resistance and decreased mucosal-to-serosal permeability to 4-ku FITC dextran. ZnO decreased the ratios of the phosphorylated to total JNK and p38 (p-JNK/JNK and p-p38/p38), while it increased the ratio of ERK (p-ERK/ERK). Supplementation with ZnO increased intestinal TGF-β1 expression. The results indicate that supplementation with ZnO activates ERK ½, and inhibits JNK and p38 signaling pathways, and increases intestinal TGF-β1 expression in weaned pigs.

microRNA and non-canonical TGF-β signalling: implications for prostate cancer therapy

The incidence of prostate cancer is increasing worldwide and marks a significant health issue. Paired with this, current therapeutic options for advanced prostate cancer, notably androgen deprivation therapy (ADT), fail to provide a consistent level of efficacy throughout the treatment period, highlighting the need for new robust therapies. Growth factors, such as Transforming Growth Factor-beta (TGF-β), possess the ability to impede cancer development in the early stages, via alterations in either apoptosis, cell proliferation, or the promotion of cellular senescence. However, later in the pathogenesis, advanced prostate cancer cells become insensitive to the previously beneficial effects of TGF-β. The molecular mechanisms behind this acquired insensitivity are not well understood. Thus, the aim of this review is to examine the effects of a class of small non-coding RNA, microRNA (miRNA), on TGF-β signalling. The impact of miRNA on the canonical TGF-β Smad signalling pathway has been well investigated, hence, in this review, we will examine whether miRNA targeting members of non-canonical TGF-β signalling members, such as, Erk, RhoA, PI3K/Akt and JNK/p38 could provide alternate therapeutic options for advanced prostate cancer.

Partial loss of Smad signaling during in vitro progression of HPV16-immortalized human keratinocytes

Background

Disruption of the transforming growth factor-beta (TGF-β) signaling pathway is observed in many cancers, including cervical cancer, resulting in TGF-β resistance. While normal human keratinocytes (HKc) and human papillomavirus type 16-immortalized HKc (HKc/HPV16) are sensitive to the growth inhibitory effects of TGF-β, HKc/HPV16 develop resistance to TGF-β1 as they progress in vitro to a differentiation resistant phenotype (HKc/DR). The loss of sensitivity to the antiproliferative effects of TGF-β1 in HKc/DR is due, at least partially, to decreased expression of the TGF-β receptor type I. In the present study, we explored in detail whether alterations in Smad protein levels, Smad phosphorylation, or nuclear localization of Smads in response to TGF-β could contribute to the development of TGF-β resistance during in vitro progression of HKc/HPV16, and whether TGF-β induction of a Smad-responsive reporter gene was altered in HKc/DR.

Methods

Western blot analysis was used to assess Smad protein levels. In order to study Smad nuclear localization we performed indirect immunofluorescence. In addition, we determined Smad-mediated TGF-β signaling using a luciferase reporter construct.

Results

We did not find a decrease in protein levels of Smad2, Smad3 or Smad4, or an increase in the inhibitory Smad7 that paralleled the loss of sensitivity to the growth inhibitory effects of TGF-β1 observed in HKc/DR. However, we found diminished Smad2 phosphorylation, and delayed nuclear Smad3 localization in response to TGF-β1 in HKc/DR, compared to normal HKc and TGF-β sensitive HKc/HPV16. In addition, we determined that TGF-β1 induction of a Smad responsive promoter is reduced by about 50% in HKc/DR, compared to HKc/HPV16.

Conclusions

These results demonstrate that alterations in Smad protein levels are not associated with the loss of response to the antiproliferative effects of TGF-β in HKc/DR, but that diminished and delayed Smad phosphorylation and nuclear localization, and decreased Smad signaling occur in response to TGF-β in HKc/DR.

Expression and regulation of miR-17a and miR-430b in zebrafish ovarian follicles

MicroRNAs (miRNAs) are small noncoding RNAs that post-transcriptionally regulate gene expression and control many developmental and physiological processes. Oocyte maturation in fish is mainly regulated by luteinizing hormone (LH) and maturation-inducing hormone (MIH). In addition, growth factors, including members of the transforming growth factor β (TGF-β) superfamily, have also been shown to play important roles in regulating oocyte maturation. In this study, we determined the expression and regulation of two miRNAs, miR-17a and miR-430b, which potentially target signalling molecules in the TGF-β pathway, in zebrafish ovarian follicles. Using real-time PCR, we observed that miR-17a and miR-430b levels in follicular cells were significantly lower in late vitellogenic and full grown follicles than in early vitellogenic follicles. Treatment with a LH analog, human chorionic gonadotropin, significantly down-regulated miR-17a and miR-430b expression in follicular cells but had no effect on their expression in oocytes. Forskolin also inhibited follicular cell miR-430b expression; however, no significant changes in miR-17a levels were observed after Forskolin treatment. Finally, MIH did not affect the expression of these miRNAs either in follicular cells or oocytes at the time points tested. These findings suggest that miR-17a and miR-430b may be involved in the regulation of follicle development and oocyte maturation in zebrafish.

The Dual Role of TGFβ in Human Cancer: From Tumor Suppression to Cancer Metastasis

The transforming growth factor-beta (TGFβ) superfamily encompasses widespread and evolutionarily conserved polypeptide growth factors that regulate and orchestrate growth and differentiation in all cell types and tissues. While they regulate asymmetric cell division and cell fate determination during early development and embryogenesis, TGFβ family members play a major regulatory role in hormonal and immune responses, cell growth, cell death and cell immortalization, bone formation, tissue remodeling and repair, and erythropoiesis throughout adult life. The biological and physiological functions of TGFβ, the founding member of this family, and its receptors are of central importance to human diseases, particularly cancer. By regulating cell growth, death, and immortalization, TGFβ signaling pathways exert tumor suppressor effects in normal cells and early carcinomas. Thus, it is not surprising that a high number of human tumors arise due to mutations or deletions in the genes coding for the various TGFβ signaling components. As tumors develop and progress, these protective and cytostatic effects of TGFβ are often lost. TGFβ signaling then switches to promote cancer progression, invasion, and tumor metastasis. The molecular mechanisms underlying this dual role of TGFβ in human cancer will be discussed in depth in this paper, and it will highlight the challenge and importance of developing novel therapeutic strategies specifically aimed at blocking the prometastatic arm of the TGFβ signaling pathway without affecting its tumor suppressive effects.

Insulin resistance and the polycystic ovary syndrome revisited: an update on mechanisms and implications

Polycystic ovary syndrome (PCOS) is now recognized as an important metabolic as well as reproductive disorder conferring substantially increased risk for type 2 diabetes. Affected women have marked insulin resistance, independent of obesity. This article summarizes the state of the science since we last reviewed the field in the Endocrine Reviews in 1997. There is general agreement that obese women with PCOS are insulin resistant, but some groups of lean affected women may have normal insulin sensitivity. There is a post-binding defect in receptor signaling likely due to increased receptor and insulin receptor substrate-1 serine phosphorylation that selectively affects metabolic but not mitogenic pathways in classic insulin target tissues and in the ovary. Constitutive activation of serine kinases in the MAPK-ERK pathway may contribute to resistance to insulin's metabolic actions in skeletal muscle. Insulin functions as a co-gonadotropin through its cognate receptor to modulate ovarian steroidogenesis. Genetic disruption of insulin signaling in the brain has indicated that this pathway is important for ovulation and body weight regulation. These insights have been directly translated into a novel therapy for PCOS with insulin-sensitizing drugs. Furthermore, androgens contribute to insulin resistance in PCOS. PCOS may also have developmental origins due to androgen exposure at critical periods or to intrauterine growth restriction. PCOS is a complex genetic disease, and first-degree relatives have reproductive and metabolic phenotypes. Several PCOS genetic susceptibility loci have been mapped and replicated. Some of the same susceptibility genes contribute to disease risk in Chinese and European PCOS populations, suggesting that PCOS is an ancient trait.

Targeting the TGFβ signalling pathway in disease

Many drugs that target transforming growth factor-β (TGFβ) signalling have been developed, some of which have reached Phase III clinical trials for a number of disease applications. Preclinical and clinical studies indicate the utility of these agents in fibrosis and oncology, particularly in augmentation of existing cancer therapies, such as radiation and chemotherapy, as well as in tumour vaccines. There are also reports of specialized applications, such as the reduction of vascular symptoms of Marfan syndrome. Here, we consider why the TGFβ signalling pathway is a drug target, the potential clinical applications of TGFβ inhibition, the issues arising with anti-TGFβ therapy and how these might be tackled using personalized approaches to dosing, monitoring of biomarkers as well as brief and/or localized drug-dosing regimens.

The influence of delayed compressive stress on TGF-β1-induced chondrogenic differentiation of rat BMSCs through Smad-dependent and Smad-independent pathways

Mechanical stimuli play important roles in regulating chondrogenic differentiation, but seldom studies have focused on when and how mechanical stimuli should be initiated. We have previously shown that Col2α1 mRNA was increased by delayed dynamic compressive stress initiated at the 8th day of chondrogenic culture. The current work is to further study the possibility of using delayed mechanical stress to relay chondrogenesis initiated by exogenous TGF-β1. Mechanical stimulation was delivered from day 8 to day 14 of chondrogenic culture. It showed that delayed compressive stress not only stimulated gene expression and protein synthesis of chondrocyte-specific markers, but also stimulated the endogenous TGF-β1 gene transcription, protein expression and the subsequent activation even when exogenous TGF-β1 was discontinued. Furthermore, mechanical stress also promoted protein phosphorylation and nuclear translocation of Smad2/3, the TGF-β1 downstream effectors. Inhibition TGF-β with SB431542 significantly affected the stress-induced chondrogenic gene expression. In addition, phosphorylated-p38 and RhoB were upregulated by delayed loading in a TGF-β-related manner. Phosphorylated-ERK1/2 and Wnt7a were also increased, but in a TGF-β-independent way. It indicates that delayed compressive stress can be used as an effective substitute for TGF-β1 supplement in inducing chondrogenic differentiation.

Thrombospondin-1 (TSP-1) analogs ABT-510 and ABT-898 inhibit prolactinoma growth and recover active pituitary transforming growth factor-β1 (TGF-β1)

Prolactinomas are the most prevalent type of secreting pituitary tumors in humans and generally respond well to a medical therapy with dopamine agonists. However, for patients exhibiting resistance to dopaminergic drugs, alternative treatments are desired. Antiangiogenic strategies might represent a potential therapy for these tumors. Thrombospondin 1 (TSP-1) is a large multifunctional glycoprotein involved in multiple biological processes including angiogenesis, apoptosis, and activation of TGF-β1. Because tumors that overexpress TSP-1 grow more slowly, have fewer metastases, and have decreased angiogenesis, TSP-1 provides a novel target for cancer treatment. ABT-510 and ABT-898 are TSP-1 synthetic analogs that mimic its antiangiogenic action. In the present study, we explored the potential effect of ABT-510 and ABT-898 on experimental prolactinomas induced by chronic diethylstilbestrol (DES) treatment in female rats. We demonstrated that a 2-wk treatment with ABT-510 and ABT-898 counteracted the increase in pituitary size and serum prolactin levels as well as the pituitary proliferation rate induced by DES. These inhibitory effects on tumor growth could be mediated by the antiangiogenic properties of the drugs. We also demonstrated that ABT-510 and ABT-898, in addition to their described antiangiogenic effects, increased active TGF-β1 level in the tumors. We postulate that the recovery of the local cytokine activation participates in the inhibition of lactotrope function. These results place these synthetic TSP-1 analogs as potential alternative or complementary treatments in dopamine agonist-resistant prolactinomas.

The potential role of microRNAs in regulating gonadal sex differentiation in the chicken embryo

Differential gene expression regulates tissue morphogenesis. The embryonic gonad is a good example, where the developmental decision to become an ovary or testis is governed by female- or male-specific gene expression. A number of genes have now been identified that control gonadal sex differentiation. However, the potential role of microRNAs (miRNAs) in ovarian and testicular pathways is unknown. In this review, we summarise our current understanding of gonadal differentiation and the possible involvement of miRNAs, using the chicken embryo as a model system. Chickens and other birds have a ZZ/ZW sex chromosome system, in which the female, ZW, is the heterogametic sex, and the male, ZZ, is homogametic (opposite to mammals). The Z-linked DMRT1 gene is thought to direct testis differentiation during embryonic life via a dosage-based mechanism. The conserved SOX9 gene is also likely to play a key role in testis formation. No master ovary determinant has yet been defined, but the autosomal FOXL2 and Aromatase genes are considered central. No miRNAs have been definitively shown to play a role in embryonic gonadal development in chickens or any other vertebrate species. Using next generation sequencing, we carried out an expression-based screen for miRNAs expressed in embryonic chicken gonads at the time of sexual differentiation. A number of miRNAs were identified, including several that showed sexually dimorphic expression. We validated a subset of miRNAs by qRT-PCR, and prediction algorithms were used to identify potential targets. We discuss the possible roles for these miRNAs in gonadal development and how these roles might be tested in the avian model.

Ingredients of Huangqi decoction slow biliary fibrosis progression by inhibiting the activation of the transforming growth factor-beta signaling pathway

BACKGROUND

Huangqi decoction was first described in Prescriptions of the Bureau of Taiping People's Welfare Pharmacy in Song Dynasty (AD 1078), and it is an effective recipe that is usually used to treat consumptive disease, anorexia, and chronic liver diseases. Transforming growth factor beta 1 (TGFβ1) plays a key role in the progression of liver fibrosis, and Huangqi decoction and its ingredients (IHQD) markedly ameliorated hepatic fibrotic lesions induced by ligation of the common bile duct (BDL). However, the mechanism of IHQD on hepatic fibrotic lesions is not yet clear. The purpose of the present study is to elucidate the roles of TGFβ1 activation, Smad-signaling pathway, and extracellular signal-regulated kinase (ERK) in the pathogenesis of biliary fibrosis progression and the antifibrotic mechanism of IHQD.

METHODS

A liver fibrosis model was induced by ligation of the common bile duct (BDL) in rats. Sham-operation was performed in control rats. The BDL rats were randomly divided into two groups: the BDL group and the IHQD group. IHQD was administrated intragastrically for 4 weeks. At the end of the fifth week after BDL, animals were sacrificed for sampling of blood serum and liver tissue. The effect of IHQD on the TGFβ1 signaling pathway was evaluated by western blotting and laser confocal microscopy.

RESULTS

Decreased content of hepatic hydroxyproline and improved liver function and histopathology were observed in IHQD rats. Hepatocytes, cholangiocytes, and myofibroblasts in the cholestatic liver injury released TGFβ1, and activated TGFβ1 receptors can accelerate liver fibrosis. IHQD markedly inhibited the protein expression of TGFβ1, TGFβ1 receptors, Smad3, and p-ERK1/2 expression with no change of Smad7 expression.

CONCLUSION

IHQD exert significant therapeutic effects on BDL-induced fibrosis in rats through inhibition of the activation of TGFβ1-Smad3 and TGFβ1-ERK1/2 signaling pathways.

Review: The skeletal muscle extracellular matrix: Possible roles in the regulation of muscle development and growth

Velleman, S. G., Shin, J., Li, X. and Song, Y. 2012. Review: The skeletal muscle extracellular matrix: Possible roles in the regulation of muscle development and growth. Can. J. Anim. Sci. 92: 1–10. Skeletal muscle fibers are surrounded by an extrinsic extracellular matrix environment. The extracellular matrix is composed of collagens, proteoglycans, glycoproteins, growth factors, and cytokines. How the extracellular matrix influences skeletal muscle development and growth is an area that is not completely understood at this time. Studies on myogenesis have largely been directed toward the cellular components and overlooked that muscle cells secrete a complex extracellular matrix network. The extracellular matrix modulates muscle development by acting as a substrate for muscle cell migration, growth factor regulation, signal transduction of information from the extracellular matrix to the intrinsic cellular environment, and provides a cellular structural architecture framework necessary for tissue function. This paper reviews extracellular matrix regulation of muscle growth with a focus on secreted proteoglycans, cell surface proteoglycans, growth factors and cytokines, and the dynamic nature of the skeletal muscle extracellular matrix, because of its impact on the regulation of muscle cell proliferation and differentiation during myogenesis.