Interdependent SMAD and JNK signaling in transforming growth factor-beta-mediated transcription

Liver Fibrosis: From Basic Science towards Clinical Progress, Focusing on the Central Role of Hepatic Stellate Cells

The burden of chronic liver disease is globally increasing at an alarming rate. Chronic liver injury leads to liver inflammation and fibrosis (LF) as critical determinants of long-term outcomes such as cirrhosis, liver cancer, and mortality. LF is a wound-healing process characterized by excessive deposition of extracellular matrix (ECM) proteins due to the activation of hepatic stellate cells (HSCs). In the healthy liver, quiescent HSCs metabolize and store retinoids. Upon fibrogenic activation, quiescent HSCs transdifferentiate into myofibroblasts; lose their vitamin A; upregulate α-smooth muscle actin; and produce proinflammatory soluble mediators, collagens, and inhibitors of ECM degradation. Activated HSCs are the main effector cells during hepatic fibrogenesis. In addition, the accumulation and activation of profibrogenic macrophages in response to hepatocyte death play a critical role in the initiation of HSC activation and survival. The main source of myofibroblasts is resident HSCs. Activated HSCs migrate to the site of active fibrogenesis to initiate the formation of a fibrous scar. Single-cell technologies revealed that quiescent HSCs are highly homogenous, while activated HSCs/myofibroblasts are much more heterogeneous. The complex process of inflammation results from the response of various hepatic cells to hepatocellular death and inflammatory signals related to intrahepatic injury pathways or extrahepatic mediators. Inflammatory processes modulate fibrogenesis by activating HSCs and, in turn, drive immune mechanisms via cytokines and chemokines. Increasing evidence also suggests that cellular stress responses contribute to fibrogenesis. Recent data demonstrated that LF can revert even at advanced stages of cirrhosis if the underlying cause is eliminated, which inhibits the inflammatory and profibrogenic cells. However, despite numerous clinical studies on plausible drug candidates, an approved antifibrotic therapy still remains elusive. This state-of-the-art review presents cellular and molecular mechanisms involved in hepatic fibrogenesis and its resolution, as well as comprehensively discusses the drivers linking liver injury to chronic liver inflammation and LF.

Network model of skeletal muscle cell signalling predicts differential responses to endurance and resistance exercise training

Exercise-induced muscle adaptations vary based on exercise modality and intensity. We constructed a signalling network model from 87 published studies of human or rodent skeletal muscle cell responses to endurance or resistance exercise in vivo or simulated exercise in vitro. The network comprises 259 signalling interactions between 120 nodes, representing eight membrane receptors and eight canonical signalling pathways regulating 14 transcriptional regulators, 28 target genes and 12 exercise-induced phenotypes. Using this network, we formulated a logic-based ordinary differential equation model predicting time-dependent molecular and phenotypic alterations following acute endurance and resistance exercises. Compared with nine independent studies, the model accurately predicted 18/21 (85%) acute responses to resistance exercise and 12/16 (75%) acute responses to endurance exercise. Detailed sensitivity analysis of differential phenotypic responses to resistance and endurance training showed that, in the model, exercise regulates cell growth and protein synthesis primarily by signalling via mechanistic target of rapamycin, which is activated by Akt and inhibited in endurance exercise by AMP-activated protein kinase. Endurance exercise preferentially activates inflammation via reactive oxygen species and nuclear factor κB signalling. Furthermore, the expected preferential activation of mitochondrial biogenesis by endurance exercise was counterbalanced in the model by protein kinase C in response to resistance training. This model provides a new tool for investigating cross-talk between skeletal muscle signalling pathways activated by endurance and resistance exercise, and the mechanisms of interactions such as the interference effects of endurance training on resistance exercise outcomes.

Cell type-specific transforming growth factor-β (TGF-β) signaling in the regulation of salivary gland fibrosis and regeneration

Salivary gland damage and hypofunction result from various disorders, including autoimmune Sjögren's disease (SjD) and IgG4-related disease (IgG4-RD), as well as a side effect of radiotherapy for treating head and neck cancers. There are no therapeutic strategies to prevent the loss of salivary gland function in these disorders nor facilitate functional salivary gland regeneration. However, ongoing aquaporin-1 gene therapy trials to restore saliva flow show promise. To identify and develop novel therapeutic targets, we must better understand the cell-specific signaling processes involved in salivary gland regeneration. Transforming growth factor-β (TGF-β) signaling is essential to tissue fibrosis, a major endpoint in salivary gland degeneration, which develops in the salivary glands of patients with SjD, IgG4-RD, and radiation-induced damage. Though the deposition and remodeling of extracellular matrix proteins are essential to repair salivary gland damage, pathological fibrosis results in tissue hardening and chronic salivary gland dysfunction orchestrated by multiple cell types, including fibroblasts, myofibroblasts, endothelial cells, stromal cells, and lymphocytes, macrophages, and other immune cell populations. This review is focused on the role of TGF-β signaling in the development of salivary gland fibrosis and the potential for targeting TGF-β as a novel therapeutic approach to regenerate functional salivary glands. The studies presented highlight the divergent roles of TGF-β signaling in salivary gland development and dysfunction and illuminate specific cell populations in damaged or diseased salivary glands that mediate the effects of TGF-β. Overall, these studies strongly support the premise that blocking TGF-β signaling holds promise for the regeneration of functional salivary glands.

TGFβR1 inhibition drives hepatocellular carcinoma proliferation through induction of toll-like-receptor signalling

Transforming growth factor (TGF)-β and toll-like receptors (TLRs) have been shown to independently modulate the proliferation of hepatocellular carcinoma (HCC). Since a direct cross-talk between these two signalling pathways in HCC has not been clearly described before, we aimed here to explore the possibility of such interaction. A human HCC tissue array (n = 20 vs. four control samples), human HCC samples (n = 10) and steatohepatitis-driven murine HCC samples (control, NASH and HCC; n = 6/group) were immunostained for TGFβR1, pSMAD2, TRAF6, IRAK1 and PCNA. The results were confirmed by immunoblotting. Effects of constant activation of the SMAD pathway by constitutive expression of ALK5 or knockdown of mediators of TLR signalling, IRAK1 and MyD88, on HCC proliferation, were investigated in the HCC cell line (HUH-7) after treatment with TGFβ1 cytokine or TGFβR1 kinase inhibitor (LY2157299) using PCNA and MTS assay. TGFβR1 expression is decreased in human and murine HCC and associated with downregulated pSMAD2, but increased IRAK1, TRAF6 and PCNA staining. TGFβR1 kinase inhibition abolished the cytostatic effects of TGFβ1 and led to the induction of IRAK1, pIRAK1 and elevated mRNA levels of TLR-9. Overexpression of ALK5 and knockdown of MyD88 or IRAK1 augmented the cytostatic effects of TGFβ1 on HUH-7. In another epithelial HCC cell line, that is, HepG2, TGFβR1 kinase inhibitor similarly elevated cellular proliferation. There is a balance between the canonical SMAD-driven tumour-suppressing arm and the non-canonical tumour-promoting arm of TGFβ signalling. Disruption of this balance, by inhibition of the canonical pathway, induces HCC proliferation through TLR signalling.

TGF-β signaling in health, disease, and therapeutics

Transforming growth factor (TGF)-β is a multifunctional cytokine expressed by almost every tissue and cell type. The signal transduction of TGF-β can stimulate diverse cellular responses and is particularly critical to embryonic development, wound healing, tissue homeostasis, and immune homeostasis in health. The dysfunction of TGF-β can play key roles in many diseases, and numerous targeted therapies have been developed to rectify its pathogenic activity. In the past decades, a large number of studies on TGF-β signaling have been carried out, covering a broad spectrum of topics in health, disease, and therapeutics. Thus, a comprehensive overview of TGF-β signaling is required for a general picture of the studies in this field. In this review, we retrace the research history of TGF-β and introduce the molecular mechanisms regarding its biosynthesis, activation, and signal transduction. We also provide deep insights into the functions of TGF-β signaling in physiological conditions as well as in pathological processes. TGF-β-targeting therapies which have brought fresh hope to the treatment of relevant diseases are highlighted. Through the summary of previous knowledge and recent updates, this review aims to provide a systematic understanding of TGF-β signaling and to attract more attention and interest to this research area.

Signaling pathways underlying TGF-β mediated suppression of IL-12A gene expression in monocytes

Transforming growth factor-β (TGF-β) is a pleiotropic cytokine essential for multiple biological processes, including the regulation of inflammatory and immune responses. One of the important functions of TGF-β is the suppression of the proinflammatory cytokine interleukin-12 (IL-12), which is crucial for mounting an anti-tumorigenic response. Although the regulation of the IL-12p40 subunit (encoded by the IL-12B gene) of IL-12 has been extensively investigated, the knowledge of IL-12p35 (encoded by IL-12A gene) subunit regulation is relatively limited. This study investigates the molecular regulation of IL-12A by TGF-β-activated signaling pathways in THP-1 monocytes. Our study identifies a complex regulation of IL-12A gene expression by TGF-β, which involves multiple cellular signaling pathways, such as Smad2/3, NF-κB, p38 and JNK1/2. Pharmacological inhibition of NF-κB signaling decreased IL-12A expression, while blocking the Smad2/3 signaling pathway by overexpression of Smad7 and inhibiting JNK1/2 signaling with a pharmacological inhibitor, SP600125, increased its expression. The elucidated signaling pathways that regulate IL-12A gene expression potentially provide new therapeutic targets to increase IL-12 levels in the tumor microenvironment.

Decrypting the Pathological Pathways in IgA Nephropathy

IgAN is the most common form of glomerulonephritis affecting 2000000 people annually. The disease ultimately progresses to chronic renal failure and ESRD. In this article, we focused on a comprehensive understanding of the pathogenesis of the disease and thus identifying different target proteins that could be essential in therapeutic approaches in the management of the disease. Aberrantly glycosylated IgA1 produced by the suppression of the enzyme β-1, 3 galactosyltransferase ultimately triggered the formation of IgG autoantibodies which form complexes with Gd-IgA1. The complex gets circulated through the blood vessels through monocytes and ultimately gets deposited in the glomerular mesangial cells via CD71 receptors present locally. This complex triggers the inflammatory pathways activating the alternate complement system, various types of T Cells, toll-like receptors, cytokines, and chemokines ultimately recruiting the phagocytic cells to eliminate the Gd-IgA complex. The inflammatory proteins cause severe mesangial and podocyte damage in the kidney which ultimately initiates the repair process following chronic inflammation by an important protein named TGFβ1. TGF β1 is an important protein produced during chronic inflammation mediating the repair process via various downstream transduction proteins and ultimately producing fibrotic proteins which help in the repair process but permanently damage the glomerular cells.

Classical cadherins in the testis: how are they regulated?

Cadherins (CDH) are crucial intercellular adhesion molecules, contributing to morphogenesis and creating tissue barriers by regulating cells' movement, clustering and differentiation. In the testis, classical cadherins such as CDH1, CDH2 and CDH3 are critical to gonadogenesis by promoting the migration and the subsequent clustering of primordial germ cells with somatic cells. While CDH2 is present in both Sertoli and germ cells in rodents, CDH1 is primarily detected in undifferentiated spermatogonia. As for CDH3, its expression is mainly found in germ and pre-Sertoli cells in developing gonads until the establishment of the blood-testis barrier (BTB). This barrier is made of Sertoli cells forming intercellular junctional complexes. The restructuring of the BTB allows the movement of early spermatocytes toward the apical compartment as they differentiate during a process called spermatogenesis. CDH2 is among many junctional proteins participating in this process and is regulated by several pathways. While cytokines promote the disassembly of the BTB by enhancing junctional protein endocytosis for degradation, testosterone facilitates the assembly of the BTB by increasing the recycling of endocytosed junctional proteins. Mitogen-activated protein kinases (MAPKs) are also mediators of the BTB kinetics in many chemically induced damages in the testis. In addition to regulating Sertoli cell functions, follicle stimulating hormone can also regulate the expression of CDH2. In this review, we discuss the current knowledge on regulatory mechanisms of cadherin localisation and expression in the testis.

Atractylodinol prevents pulmonary fibrosis through inhibiting TGF-β receptor 1 recycling by stabilizing vimentin

Pirfenidone and nintedanib are only anti-pulmonary fibrosis (PF) drugs approved by the FDA. However, they are not target specific, and unable to modify the disease status. Therefore, it is still desirable to discover more effective agents against PF. Vimentin (VIM) plays key roles in tissue regeneration and wound healing, but its molecular mechanism remains unknown. In this work, we demonstrated that atractylodinol (ATD) significantly inhibits TGF-β1-induced epithelial-mesenchymal transition and fibroblast-to-myofibroblast transition in vitro. ATD also reduces bleomycin-induced lung injury and fibrosis in mice models. Mechanistically, ATD inhibited TGF-β receptor I recycling by binding to VIM (KD = 454 nM) and inducing the formation of filamentous aggregates. In conclusion, we proved that ATD (derived from Atractylodes lancea) modified PF by targeting VIM and inhibiting the TGF-β/Smad signaling pathway. Therefore, VIM is a druggable target and ATD is a proper drug candidate against PF. We prove a novel VIM function that TGF-β receptor I recycling. These findings paved the way to develop new targeted therapeutics against PF.

Role of transforming growth factor-β in airway remodelling in bronchiolitis obliterans

Airway remodelling is the main pathological mechanism of bronchiolitis obliterans (BO). Several studies have found that transforming growth factor-β (TGF-β) expression is increased in BO during airway remodelling, where it plays an important role in various biological processes by binding to its receptor complex to activate multiple signalling proteins and pathways. This review examines the role of TGF-β in airway remodelling in BO and its potential as a therapeutic target, highlighting the mechanisms of TGF-β activation and signalling, cellular targets of TGF-β actions, and research progress in TGF-β signalling and TGF-β-mediated processes.

JNK Signalling Regulates Self-Renewal of Proliferative Urine-Derived Renal Progenitor Cells via Inhibition of Ferroptosis

With a global increase in chronic kidney disease patients, alternatives to dialysis and organ transplantation are needed. Stem cell-based therapies could be one possibility to treat chronic kidney disease. Here, we used multipotent urine-derived renal progenitor cells (UdRPCs) to study nephrogenesis. UdRPCs treated with the JNK inhibitor-AEG3482 displayed decreased proliferation and downregulated transcription of cell cycle-associated genes as well as the kidney progenitor markers-SIX2, SALL1 and VCAM1. In addition, levels of activated SMAD2/3, which is associated with the maintenance of self-renewal in UdRPCs, were decreased. JNK inhibition resulted in less efficient oxidative phosphorylation and more lipid peroxidation via ferroptosis, an iron-dependent non-apoptotic cell death pathway linked to various forms of kidney disease. Our study is the first to describe the importance of JNK signalling as a link between maintenance of self-renewal and protection against ferroptosis in SIX2-positive renal progenitor cells.

The effect of extracorporeal shock wave on joint capsule fibrosis in rats with knee extension contracture: a preliminary study

The purpose of this study was to observe the therapeutic effect of extracorporeal shock wave (ESW) on extensional joint contracture of knee joint in rats and its mechanism on articular capsule fibrosis. Thirty-two SD rats were randomly divided into blank control, immobilization, natural recovery, and ESW intervention groups. Except for the control group, the left knee joints of other rats were fixed with external fixation brace for 4 weeks when they were fully extended to form joint contracture. The effect of intervention was assessed by evaluating joint contracture, total cell count and collagen deposition in joint capsule, and protein expression levels of TGF-β1, p-Smad2/3, Smad2/3, p-JNK, JNK, I and III collagen in joint capsule. ESW can effectively reduce arthrogenic contracture, improve the histopathological changes of anterior joint capsule, inhibit the high expression of target protein and the excessive activation of TGF-β1/Smad2/3/JNK signal pathway. Inhibition of excessive activation of TGF-β1/Smad2/3/JNK pathway may be one of the potential molecular mechanisms by which extracorporeal shock wave can play a role.

Salvianolic Acid A Improves Rat Kidney Injury by Regulating MAPKs and TGF-β1/Smads Signaling Pathways

Salvianolic acid A (SAA) is one of the major components in Salvia miltiorrhiza Bge., with various pharmacological activities, and is likely to be a promising agent for the treatment of kidney diseases. The purpose of this study was to explore the protective effect and mechanisms of SAA on kidney disease. In this study, the improvement effects of SAA (10, 20, 40 mg/kg, i.g.) on kidney injury rats were investigated by detecting the levels of KIM-1, NGAL in serum and UP in the urine of AKI model rats established with gentamicin, as well as the levels of SCr and UREA in serum and IL-6, IL-12, MDA and T-SOD in the kidneys of CKD model rats established with 5/6 nephrectomy. HE and Masson staining were used to observe the histopathological changes in the kidney. Network pharmacology and Western blotting were used to explore the mechanism of SAA in improving kidney injury. The results showed that SAA improved kidney function in kidney injury rats by reducing the kidney index and pathological injury by HE and Masson staining, reducing the levels of KIM-1, NGAL and UP in AKI rats and UREA, SCr and UP in CKD rats, as well as exerting anti-inflammatory and anti-oxidative stress effects by inhibiting the release of IL-6 and IL-12, reducing MDA and increasing T-SOD. Western blotting results showed that SAA significantly reduced the phosphorylation levels of ERK1/2, p38, JNK and smad2/3, and the expression of TLR-4 and smad7. In conclusion, SAA plays a significant role in improving kidney injury in rats and the mechanism may be achieved by regulating the MAPKs and TGF-β1/smads signaling pathways.

Tonic repression of Collagen I by the Bradykinin receptor 2 in skin fibroblasts

Imbalance of collagen I expression results in severe pathologies. Apart from activation by the TGFβ-receptor/Smad pathway, control of collagen I expression remains poorly understood. Here, we used human dermal fibroblasts expressing a mCherry fluorescent protein driven by endogenous COL1A1 promoter to functionally screen the kinome and phosphatome. We identify 8 negative regulators, revealing that collagen is under tonic repression. The cell surface receptor BDKRB2 represses collagen I and other pro-fibrotic genes. Interestingly, it also promotes other basal membrane ECM genes. This function is independent of the natural ligand, bradykinin, and of SMAD2/3 factors, instead requiring constant ERK1/2 repression. TGFβ stimulation induces rapid BDKRB2 transcriptional downregulation. Human fibrotic fibroblasts have reduced BDKRB2 levels and enhancing its expression in keloid fibroblasts represses COL1A1. We propose that tonic signalling by BDKRB2 prevents collagen overproduction in skin fibroblasts.

Hepatic Stellate Cells: Dictating Outcome in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a fast growing, chronic liver disease affecting ∼25% of the global population. Nonalcoholic fatty liver disease severity ranges from the less severe simple hepatic steatosis to the more advanced nonalcoholic steatohepatitis (NASH). The presence of NASH predisposes individuals to liver fibrosis, which can further progress to cirrhosis and hepatocellular carcinoma. This makes hepatic fibrosis an important indicator of clinical outcomes in patients with NASH. Hepatic stellate cell activation dictates fibrosis development during NASH. Here, we discuss recent advances in the analysis of the profibrogenic pathways and mediators of hepatic stellate cell activation and inactivation, which ultimately determine the course of disease in nonalcoholic fatty liver disease/NASH.

Exploring the cardiac ECM during fibrosis: A new era with next-gen proteomics

Extracellular matrix (ECM) plays a critical role in maintaining elasticity in cardiac tissues. Elasticity is required in the heart for properly pumping blood to the whole body. Dysregulated ECM remodeling causes fibrosis in the cardiac tissues. Cardiac fibrosis leads to stiffness in the heart tissues, resulting in heart failure. During cardiac fibrosis, ECM proteins get excessively deposited in the cardiac tissues. In the ECM, cardiac fibroblast proliferates into myofibroblast upon various kinds of stimulations. Fibroblast activation (myofibroblast) contributes majorly toward cardiac fibrosis. Other than cardiac fibroblasts, cardiomyocytes, epithelial/endothelial cells, and immune system cells can also contribute to cardiac fibrosis. Alteration in the expression of the ECM core and ECM-modifier proteins causes different types of cardiac fibrosis. These different components of ECM culminated into different pathways inducing transdifferentiation of cardiac fibroblast into myofibroblast. In this review, we summarize the role of different ECM components during cardiac fibrosis progression leading to heart failure. Furthermore, we highlight the importance of applying mass-spectrometry-based proteomics to understand the key changes occurring in the ECM during fibrotic progression. Next-gen proteomics studies will broaden the potential to identify key targets to combat cardiac fibrosis in order to achieve precise medicine-development in the future.

β-Asarone suppresses TGF-β/Smad signaling to reduce the invasive properties in esophageal squamous cancer cells

Esophageal cancer is one of the most common malignancies which induces cancer-related death. Cancer metastasis and recurrence are the main obstacle faced in esophageal cancer treatment. β-Asarone has been shown to act as an anti-cancer reagent in various cancer types. However, the anti-cancer activities of β-Asarone in esophageal cancer have not been shown. In the current study, we show that β-Asarone suppressed the proliferation of esophageal squamous cancer cells (ESCC) in both dose- and time-dependent manners. Moreover, β-Asarone treatment increases activated caspase 3, caspase 9, and cleaved poly ADP-ribose polymerase, and induces apoptosis in ESCC. Additionally, β-Asarone also suppresses epithelial-mesenchymal transition (EMT) and the invasive and migratory abilities in ESCC. Interestingly, β-Asarone suppresses TGF-β/Smad signaling by inhibition of TGF-β-induced phosphorylation of Smad2 and Smad3. Importantly, we show that inhibition of TGF-β/Smad signaling activation is critical for β-Asarone-suppressed EMT. Our data revealed a novel role of β-Asarone which targets invasive properties by inhibiting TGF-β/Smad signaling activation in ESCC. Our study suggests the potential application of β-Asarone to reduce cancer metastasis and recurrence in esophageal cancer treatment.

TGF-β signaling in myeloproliferative neoplasms contributes to myelofibrosis without disrupting the hematopoietic niche

Myeloproliferative neoplasms (MPNs) are associated with significant alterations in the bone marrow microenvironment that include decreased expression of key niche factors and myelofibrosis. Here, we explored the contribution of TGF-β to these alterations by abrogating TGF-β signaling in bone marrow mesenchymal stromal cells. Loss of TGF-β signaling in Osx-Cre-targeted MSCs prevented the development of myelofibrosis in both MPLW515L and Jak2V617F models of MPNs. In contrast, despite the absence of myelofibrosis, loss of TGF-β signaling in mesenchymal stromal cells did not rescue the defective hematopoietic niche induced by MPLW515L, as evidenced by decreased bone marrow cellularity, hematopoietic stem/progenitor cell number, and Cxcl12 and Kitlg expression, and the presence of splenic extramedullary hematopoiesis. Induction of myelofibrosis by MPLW515L was intact in Osx-Cre Smad4fl/fl recipients, demonstrating that SMAD4-independent TGF-β signaling mediates the myelofibrosis phenotype. Indeed, treatment with a c-Jun N-terminal kinase (JNK) inhibitor prevented the development of myelofibrosis induced by MPLW515L. Together, these data show that JNK-dependent TGF-β signaling in mesenchymal stromal cells is responsible for the development of myelofibrosis but not hematopoietic niche disruption in MPNs, suggesting that the signals that regulate niche gene expression in bone marrow mesenchymal stromal cells are distinct from those that induce a fibrogenic program.

TGF-β signaling in myeloproliferative neoplasms contributes to myelofibrosis without disrupting the hematopoietic niche

Myeloproliferative neoplasms (MPNs) are associated with significant alterations in the bone marrow microenvironment that include decreased expression of key niche factors and myelofibrosis. Here, we explored the contribution of TGF-β to these alterations by abrogating TGF-β signaling in bone marrow mesenchymal stromal cells. Loss of TGF-β signaling in Osx-Cre-targeted MSCs prevented the development of myelofibrosis in both MPLW515L and Jak2V617F models of MPNs. In contrast, despite the absence of myelofibrosis, loss of TGF-β signaling in mesenchymal stromal cells did not rescue the defective hematopoietic niche induced by MPLW515L, as evidenced by decreased bone marrow cellularity, hematopoietic stem/progenitor cell number, and Cxcl12 and Kitlg expression, and the presence of splenic extramedullary hematopoiesis. Induction of myelofibrosis by MPLW515L was intact in Osx-Cre Smad4fl/fl recipients, demonstrating that SMAD4-independent TGF-β signaling mediates the myelofibrosis phenotype. Indeed, treatment with a c-Jun N-terminal kinase (JNK) inhibitor prevented the development of myelofibrosis induced by MPLW515L. Together, these data show that JNK-dependent TGF-β signaling in mesenchymal stromal cells is responsible for the development of myelofibrosis but not hematopoietic niche disruption in MPNs, suggesting that the signals that regulate niche gene expression in bone marrow mesenchymal stromal cells are distinct from those that induce a fibrogenic program.

Advantages and drawbacks of dexamethasone in glioblastoma multiforme

The most widespread, malignant, and deadliest type of glial tumor is glioblastoma multiforme (GBM). Despite radiation, chemotherapy, and radical surgery, the median survival of afflicted individuals is about 12 months. Unfortunately, existing therapeutic interventions are abysmal. Dexamethasone (Dex), a synthetic glucocorticoid, has been used for many years to treat brain edema and inflammation caused by GBM. Several investigations have recently shown that Dex also exerts antitumoral effects against GBM. On the other hand, more recent disputed findings have questioned the long-held dogma of Dex treatment for GBM. Unfortunately, steroids are associated with various undesirable side effects, including severe immunosuppression and metabolic changes like hyperglycemia, which may impair the survival of GBM patients. Current ideas and concerns about Dex's effects on GBM cerebral edema, cell proliferation, migration, and its clinical outcomes were investigated in this study.

Overexpression of bone morphogenetic protein receptor type 2 suppresses transforming growth factor β-induced profibrotic responses in lung fibroblasts

MATERIALS AND METHODS

We investigated BMPR2 expression in pulmonary fibrosis and TGF-β/BMP signaling in lung fibroblasts. Then we evaluated the impact of BMPR2 upregulation using adenoviral transduction on TGF-β-induced Smad2/3 phosphorylation and fibronectin production in lung fibroblasts.

RESULTS

BMPR2 was distributed in airway epithelium and alveolar walls in rat lungs. BMPR2 expression was decreased in fibrotic lesions in the lungs of rats with bleomycin-induced pulmonary fibrosis and in human lung fibroblasts (HLFs) stimulated with TGF-β. Although Smad2/3 phosphorylation and fibronectin production were not suppressed solely by BMPs, phosphorylated Smad2/3 was decreased in BMPR2-transduced cells even without BMP stimulation. Fibronectin was decreased only when BMPR2-transduced HLFs were stimulated with BMP7 (but not BMP4). Similar results were also observed in IPF patient HLFs and rat lung fibroblasts.

CONCLUSIONS

BMPR2 expression was reduced in fibrotic lungs and lung fibroblasts stimulated with TGF-β. BMPR2 transduction to lung fibroblasts reduced Smad2/3 phosphorylation, and reduced fibronectin production when treated with BMP7. Upregulation of BMPR2 may be a possible strategy for treating pulmonary fibrosis.

Germacrone Attenuates Hepatic Stellate Cells Activation and Liver Fibrosis via Regulating Multiple Signaling Pathways

Liver fibrosis is an abnormal proliferation of connective tissue in the liver caused by various pathogenic factors. Chronic liver injury leads to release of inflammatory cytokines and reactive oxygen species (ROS) from damaged hepatocytes, which activates hepatic stellate cells (HSCs) to secrete extracellular matrix proteins, thereby leading to fibrosis. Thus, inhibition of hepatocyte injury and HSC activation, and promotion of apoptosis of activated HSCs are important strategies for prevention of liver fibrosis. In this study, we showed that the germacrone (GER), the main component in the volatile oil of zedoary turmeric, inhibited hepatic fibrosis by regulating multiple signaling pathways. First, GER improved the cell survival rate by inhibiting the production of ROS after hepatocyte injury caused by acetaminophen (APAP). In addition, GER inhibited the activation of HSCs and expression of collagen I by blocking TGF-β/Smad pathway in LX-2 cells. However, when the concentration of GER was higher than 60 μM, it specifically induced HSCs apoptosis by promoting the expression and activation of apoptosis-related proteins, but it had no effect on hepatocytes. Importantly, GER significantly attenuated the methionine- and choline-deficient (MCD) diet-induced liver fibrosis by inhibiting liver injury and the activation of HSCs in vivo. In summary, GER can not only protect hepatocytes by reducing ROS release to avoid the liver injury-induced HSC activation, but also directly inhibit the activation and survival of HSCs by regulating TGF-β/Smad and apoptosis pathways. These results demonstrate that GER can be used as a potential therapeutic drug for the treatment of liver fibrosis.

Canonical TGFβ Signaling and Its Contribution to Endometrial Cancer Development and Progression-Underestimated Target of Anticancer Strategies

Endometrial cancer is one of the leading gynecological cancers diagnosed among women in their menopausal and postmenopausal age. Despite the progress in molecular biology and medicine, no efficient and powerful diagnostic and prognostic marker is dedicated to endometrial carcinogenesis. The canonical TGFβ pathway is a pleiotropic signaling cascade orchestrating a variety of cellular and molecular processes, whose alterations are responsible for carcinogenesis that originates from different tissue types. This review covers the current knowledge concerning the canonical TGFβ pathway (Smad-dependent) induced by prototypical TGFβ isoforms and the involvement of pathway alterations in the development and progression of endometrial neoplastic lesions. Since Smad-dependent signalization governs opposed cellular processes, such as growth arrest, apoptosis, tumor cells growth and differentiation, as well as angiogenesis and metastasis, TGFβ cascade may act both as a tumor suppressor or tumor promoter. However, the final effect of TGFβ signaling on endometrial cancer cells depends on the cancer disease stage. The multifunctional role of the TGFβ pathway indicates the possible utilization of alterations in the TGFβ cascade as a potential target of novel anticancer strategies.

[Study on the gelatin methacryloyl composite scaffold with exogenous transforming growth factor β 1 to promote the repair of skull defects]

Objective

To prepare a bone tissue engineering scaffold for repairing the skull defect of Sprague Dawley (SD) rats by combining exogenous transforming growth factor β ₁ (TGF-β ₁) with gelatin methacryloyl (GelMA) hydrogel.

Methods

Firstly, GelMA hydrogel composite scaffolds containing exogenous TGF-β ₁ at concentrations of 0, 150, 300, 600, 900, and 1 200 ng/mL (set to groups A, B, C, D, E, and F, respectively) were prepared. Cell counting kit 8 (CCK-8) method was used to detect the effect of composite scaffold on the proliferation of bone marrow mesenchymal stem cells (BMSCs) in SD rats. ALP staining, alizarin red staining, osteocalcin (OCN) immunofluorescence staining, and Western blot were used to explore the effect of scaffolds on osteogenic differentiation of BMSCs, and the optimal concentration of TGF-β ₁/GelMA scaffold was selected. Thirty-six 8-week-old SD rats were taken to prepare a 5 mm diameter skull bone defect model and randomly divided into 3 groups, namely the control group, the GelMA group, and the GelMA+TGF-β ₁ group (using the optimal concentration of TGF-β ₁/GelMA scaffold). The rats were sacrificed at 4 and 8 weeks after operation, and micro-CT, HE staining, and OCN immunohistochemistry staining were performed to observe the repair effect of skull defects.

Results

The CCK-8 method showed that the TGF-β ₁/GelMA scaffolds in each group had a promoting effect on the proliferation of BMSCs. Group D had the strongest effect, and the cell activity was significantly higher than that of the other groups ( P<0.05). The results of ALP staining, alizarin red staining, OCN immunofluorescence staining, and Western blot showed that the percentage of ALP positive area, the percentage of alizarin red positive area, and the relative expressions of ALP and OCN proteins in group D were significantly higher than those of the other groups ( P<0.05), the osteogenesis effect in group D was the strongest. Therefore, in vitroexperiments screened out the optimal concentration of TGF-β ₁/GelMA scaffold to be 600 ng/mL. Micro-CT, HE staining, and OCN immunohistochemistry staining of rat skull defect repair experiments showed that the new bone tissue and bone volume/tissue volume ratio in the TGF-β ₁+GelMA group were significantly higher than those in the GelMA group and control group at 4 and 8 weeks after operation ( P<0.05).

Conclusion

The TGF-β ₁/GelMA scaffold with a concentration of 600 ng/mL can significantly promote the osteogenic differentiation of BMSCs, can significantly promote bone regeneration at the skull defect, and can be used as a bioactive material for bone tissue regeneration.

P-Rex1 Cooperates With TGFβR2 to Drive Lung Fibroblast Migration in Pulmonary Fibrosis

Pulmonary fibrosis is a kind of interstitial lung disease with progressive pulmonary scar formation, leading to irreversible loss of lung functions. The TGF-β1/Smad signaling pathway plays a key role in fibrogenic processes. It is associated with the increased synthesis of extracellular matrix, enhanced proliferation of fibroblasts, and transformation of alveolar epithelial cells into interstitial cells. We investigated P-Rex1, a PIP₃-Gβγ-dependent guanine nucleotide exchange factor (GEF) for Rac, for its potential role in TGF-β1-induced pulmonary fibrosis. A high expression level of P-Rex1 was identified in the lung tissue of patients with pulmonary fibrosis than that from healthy donors. Using the P-Rex1 knockdown and overexpression system, we established a novel player of P-Rex1 in mouse lung fibroblast migration. P-Rex1 contributed to fibrogenic processes in lung fibroblasts by targeting the TGF-β type Ⅱ receptor (TGFβR2). The RNA-seq analysis for expression profiling confirmed the modulation of P-Rex1 in cell migration and the involvement of P-Rex1 in TGF-β1 signaling. These results identified P-Rex1 as a signaling molecule involved in TGF-β1-induced pulmonary fibrosis, suggesting that P-Rex1 may be a potential target for pulmonary fibrosis treatment.

TGF-β signaling: A recap of SMAD-independent and SMAD-dependent pathways

Transforming growth factor-β (TGF-β) is a proinflammatory cytokine known to control a diverse array of pathological and physiological conditions during normal development and tumorigenesis. TGF-β-mediated physiological effects are heterogeneous and vary among different types of cells and environmental conditions. TGF-β serves as an antiproliferative agent and inhibits tumor development during primary stages of tumor progression; however, during the later stages, it encourages tumor development and mediates metastatic progression and chemoresistance. The fundamental elements of TGF-β signaling have been divulged more than a decade ago; however, the process by which the signals are relayed from cell surface to nucleus is very complex with additional layers added in tumor cell niches. Although the intricate understanding of TGF-β-mediated signaling pathways and their regulation are still evolving, we tried to make an attempt to summarize the TGF-β-mediated SMAD-dependent andSMAD-independent pathways. This manuscript emphasizes the functions of TGF-β as a metastatic promoter and tumor suppressor during the later and initial phases of tumor progression respectively.

PI3K as Mediator of Apoptosis and Contractile Dysfunction in TGFβ1-Stimulated Cardiomyocytes

BACKGROUND

TGFβ₁ is a growth factor that plays a major role in the remodeling process of the heart by inducing cardiomyocyte dysfunction and apoptosis, as well as fibrosis thereby restricting heart function. TGFβ₁ mediates its effect via the TGFβ receptor I (ALK5) and the activation of SMAD transcription factors, but TGFβ₁ is also known as activator of phosphoinositide-3-kinase (PI3K) via the non-SMAD signaling pathway. The aim of this study was to investigate whether PI3K is also involved in TGFβ₁-induced cardiomyocytes apoptosis and contractile dysfunction.

METHODS AND RESULTS

Incubation of isolated ventricular cardiomyocytes with TGFβ₁ resulted in impaired contractile function. Pre-incubation of cells with the PI3K inhibitor Ly294002 or the ALK5 inhibitor SB431542 attenuated the decreased cell shortening in TGFβ₁-stimulated cells. Additionally, TGFβ-induced apoptosis was significantly reduced by the PI3K inhibitor Ly294002. Administration of a PI3Kγ-specific inhibitor AS605240 abolished the TGFβ effect on apoptosis and cell shortening. This was also confirmed in cardiomyocytes from PI3Kγ KO mice. Induction of SMAD binding activity and the TGFβ target gene collagen 1 could be blocked by the PI3K inhibitor Ly294002, but not by the specific PI3Kγ inhibitor AS605240.

CONCLUSIONS

TGFβ₁-induced SMAD activation, cardiomyocyte apoptosis, and impaired cell shortening are mediated via both, the ALK5 receptor and PI3K, in adult cardiomyocytes. PI3Kγ specifically contributes to apoptosis induction and impairment of contractile function independent of SMAD signaling.

A cytokine in turmoil: Transforming growth factor beta in cancer

Cancer remains one of the debilitating health threats to mankind in view of its incurable nature. Many factors are complicit in the initiation, progression and establishment of cancers. Early detection of cancer is the only window of hope that allows for appreciable management and possible limited survival. However, understanding of cancer biology and knowledge of the key factors that interplay at multi-level in the initiation and progression of cancer may hold possible avenues for cancer treatment and management. In particular, dysregulation of growth factor signaling such as that of transforming growth factor beta (TGF-β) and its downstream mediators play key roles in various cancer subtypes. Expanded understanding of the context/cell type-dependent roles of TGF-β and its downstream signaling mediators in cancer may provide leads for cancer pharmacotherapy. Reliable information contained in original articles, reviews, mini-reviews and expert opinions on TGF-β, cancer and the specific roles of TGF-β signaling in various cancer subtypes were retrieved from major scientific data bases including PubMed, Scopus, Medline, Web of Science core collections just to mention but a sample by using the following search terms: TGF-β in cancer, TGF-β and colorectal cancer, TGF-β and brain cancer, TGF-β in cancer initiation, TGF-β and cell proliferation, TGF-β and cell invasion, and TGF-β-based cancer therapy. Retrieved information and reports were carefully examined, contextualized and synchronized into a coherent scientific content to highlight the multiple roles of TGF-β signaling in normal and cancerous cells. From a conceptual standpoint, development of pharmacologically active agents that exert non-specific inhibitory effects on TGF-β signaling on various cell types will undoubtedly lead to a plethora of serious side effects in view of the multi-functionality and pleiotropic nature of TGF-β. Such non-specific targeting of TGF-β could derail any beneficial therapeutic intention associated with TGF-β-based therapy. However, development of pharmacologically active agents designed specifically to target TGF-β signaling in cancer cells may improve cancer pharmacotherapy. Similarly, specific targeting of downstream mediators of TGF-β such as TGF-β type 1 and II receptors (TβRI and TβRII), receptor-mediated Smads, mitogen activated protein kinase (MAPK) and importing proteins in cancer cells may be crucial for cancer pharmacotherapy.

Megakaryoblastic leukemia: a study on novel role of clinically significant long non-coding RNA signatures in megakaryocyte development during treatment with phorbol ester

Acute megakaryocytic leukemia (AMKL) is one of the rarest sub-types of acute myeloid leukemia (AML). AMKL is characterized by high proliferation of megakaryoblasts and myelofibrosis of bone marrow, this disease is also associated with poor prognosis. Previous analyses have reported that the human megakaryoblastic cells can be differentiated into cells with megakaryocyte (MK)-like characteristics by phorbol 12-myristate 13-acetate (PMA). However, little is known about the mechanism responsible for regulating this differentiation process. We performed long non-coding RNA (lncRNA) profiling to investigate the differently expressed lncRNAs in megakaryocyte blast cells treated with and without PMA and examined those that may be responsible for the PMA-induced differentiation of megakaryoblasts into MKs. We found 30 out of 90 lncRNA signatures to be differentially expressed after PMA treatment of megakaryoblast cells, including the highly expressed JPX lncRNA. Further, in silico lncRNA-miRNA and miRNA-mRNA interaction analysis revealed that the JPX is likely involved in unblocking the expression of TGF-β receptor (TGF-βR) by sponging oncogenic miRNAs (miR-9-5p, miR-17-5p, and miR-106-5p) during MK differentiation. Further, we report the activation of TGF-βR-induced non-canonical ERK1/2 and PI3K/AKT pathways during PMA-induced MK differentiation and ploidy development. The present study demonstrates that TGF-βR-induced non-canonical ERK1/2 and PI3K/AKT pathways are associated with PMA-induced MK differentiation and ploidy development; in this molecular mechanism, JPX lncRNA could act as a decoy for miR-9-5p, miR-17-5p, and miR-106-5p, titrating them away from TGF-βR mRNAs. Importantly, this study reveals the activation of ERK1/2 and PI3K/AKT pathway in PMA-induced Dami cell differentiation into MK. The identified differentially expressed lncRNA signatures may facilitate further study of the detailed molecular mechanisms associated with MK development. Thus, our data provide numerous targets with therapeutic potential for the modulation of the differentiation of megakaryoblastic cells in AMKL.

Inhibition of TGF-β/Smad3 Signaling Disrupts Cardiomyocyte Cell Cycle Progression and Epithelial-Mesenchymal Transition-Like Response During Ventricle Regeneration

Unlike mammals, zebrafish can regenerate injured hearts even in the adult stage. Cardiac regeneration requires the coordination of cardiomyocyte (CM) proliferation and migration. The TGF-β/Smad3 signaling pathway has been implicated in cardiac regeneration, but the molecular mechanisms by which this pathway regulates CM proliferation and migration have not been fully illustrated. Here, we investigated the function of TGF-β/Smad3 signaling in a zebrafish model of ventricular ablation. Multiple components of this pathway were upregulated/activated after injury. Utilizing a specific inhibitor of Smad3, we detected an increased ratio of unrecovered hearts. Transcriptomic analysis suggested that the TGF-β/Smad3 signaling pathway could affect CM proliferation and migration. Further analysis demonstrated that the CM cell cycle was disrupted and the epithelial–mesenchymal transition (EMT)-like response was impaired, which limited cardiac regeneration. Altogether, our study reveals an important function of TGF-β/Smad3 signaling in CM cell cycle progression and EMT process during zebrafish ventricle regeneration.

Modulation of the inflammatory environment by spermatozoa through regulation of transforming growth factor beta in porcine uterine epithelial cells

This study investigated the changes in the mRNA expression of transforming growth factor beta (TGF-β), plasminogen activators (PAs), and interleukin (IL) caused by sperm, as well as the regulatory mechanism of PA activity through TGF-β, in porcine uterine epithelial cells. The cells were isolated from the uterine horn of pig and co-incubated with Percoll-separated boar sperm (45% or 90%), or TGF-β for 24 h. The mRNA expression of TGF-β isoforms (TGF-β1, 2 and 3) and their receptors (TGF-β R1 and R2), PAs (urokinase-type, uPA; tissue-type, tPA; uPA receptor, uPAR; type 1 PA inhibitor, PAI-1), IL-6 and IL-8 was analyzed using real-time PCR. Supernatant was used to measure PA activity. Co-incubation with sperm from the 90% Percoll layer increased TGF-β1 mRNA, whereas TGF-β2 and TGF-β3 were decreased (P < 0.05). However, both TGF-βRs were not changed by the presence of the spermatozoa. Expression of tPA, PAI-1, IL-6, and IL-8 mRNA was down-regulated by 90% Percoll-separated sperm (P < 0.05), and sperm from 45% Percoll increased uPA expression (P < 0.05). TGF-β decreased tPA and IL-8 mRNA expression, and increased uPAR and PAI-1 mRNA (P < 0.05). The suppressive effect of TGF-β on PA activity was blocked by Smad2/3 and JNK1/2 signaling inhibitors (P < 0.05). In conclusion, sperm separated in 90% in porcine uterus could suppressed inflammation via modulation of TGF-β and down-regulation of PAs and ILs. Therefore, the regulatory mechanism of inflammation by sperm in the porcine uterus could be associated with interactions between numerous cytokines including TGF-β.

Resveratrol and cardiac fibrosis prevention and treatment

Cardiovascular diseases are some of the major causes of morbidity and mortality in developed or developing countries but in developed countries as well. Cardiac fibrosis is one of the most often pathological changes of heart tissues. It occurs as a result of extracellular matrix proteins accumulation at myocardia. Cardiac fibrosis results in impaired cardiac systolic and diastolic functions and is associated with other effects. Therapies with medicines have not been sufficiently successful in treating chronic diseases such as CVD. Therefore, the interest for therapeutic potential of natural compounds and medicinal plants has increased. Plants such as grapes, berries and peanuts contain a polyphenolic compound called "resveratrol" which has been reported to have various therapeutic properties for a variety of diseases. Studies on laboratory models that show that resveratrol has beneficial effects on cardiovascular diseases including myocardial infarction, high blood pressure cardiomyopathy, thrombosis, cardiac fibrosis, and atherosclerosis. In vitro animal models using resveratrol indicated protective effects on the heart by neutralizing reactive oxygen species, preventing inflammation, increasing neoangiogenesis, dilating blood vessels, suppressing apoptosis and delaying atherosclerosis. In this review, we are presenting experimental and clinical results of studies concerning resveratrol effects on cardiac fibrosis as a CVD outcome in humans.

The Space of Disse: The Liver Hub in Health and Disease

Since it was first described by the German anatomist and histologist, Joseph Hugo Vincenz Disse, the structure and functions of the space of Disse, a thin perisinusoidal area between the endothelial cells and hepatocytes filled with blood plasma, have acquired great importance in liver disease. The space of Disse is home for the hepatic stellate cells (HSCs), the major fibrogenic players in the liver. Quiescent HSCs (qHSCs) store vitamin A, and upon activation they lose their retinol reservoir and become activated. Activated HSCs (aHSCs) are responsible for secretion of extracellular matrix (ECM) into the space of Disse. This early event in hepatic injury is accompanied by loss of the pores—known as fenestrations—of the endothelial cells, triggering loss of balance between the blood flow and the hepatocyte, and underlies the link between fibrosis and organ dysfunction. If the imbalance persists, the expansion of the fibrotic scar followed by the vascularized septae leads to cirrhosis and/or end-stage hepatocellular carcinoma (HCC). Thus, researchers have been focused on finding therapeutic targets that reduce fibrosis. The space of Disse provides the perfect microenvironment for the stem cells niche in the liver and the interchange of nutrients between cells. In the present review article, we focused on the space of Disse, its components and its leading role in liver disease development.

Diverse origins and activation of fibroblasts in cardiac fibrosis

Cardiac fibroblasts (cFBs) have emerged as a heterogenous cell population. Fibroblasts are considered the main cell source for synthesis of the extracellular matrix (ECM) and as such a dysregulation in cFB function, activity, or viability can lead to disrupted ECM structure or fibrosis. Fibrosis can be initiated in response to different injuries and stimuli, and can be reparative (beneficial) or reactive (damaging). FBs need to be activated to myofibroblasts (MyoFBs) which have augmented capacity in synthesizing ECM proteins, causing fibrosis. In addition to the resident FBs in the myocardium, a number of other cells (pericytes, fibrocytes, mesenchymal, and hematopoietic cells) can transform into MyoFBs, further driving the fibrotic response. Multiple molecules including hormones, cytokines, and growth factors stimulate this process leading to generation of activated MyoFBs. Contribution of different cell types to cFBs and MyoFBs can result in an exponential increase in the number of MyoFBs and an accelerated pro-fibrotic response. Given the diversity of the cell sources, and the array of interconnected signalling pathways that lead to formation of MyoFBs and subsequently fibrosis, identifying a single target to limit the fibrotic response in the myocardium has been challenging. This review article will delineate the importance and relevance of fibroblast heterogeneity in mediating fibrosis in different models of heart failure and will highlight important signalling pathways implicated in myofibroblast activation.

Transforming Growth Factor β1 Induces Epithelial–mesenchymal Transition by Activating the Jnk–SMAD3 Pathway in Rat Peritoneal Mesothelial Cells

⋄ Background

Peritoneal fibrosis is a serious complication in long-term peritoneal dialysis (PD) patients. Epithelial-mesenchymal transition (EMT) plays an important role in peritoneal fibrosis, and TGFβ1 is the crucial inducer of EMT. Phosphorylation of Smad proteins is required for TGFβ1-induced EMT. It was reported that C-Jun N-terminal kinase (JNK) was involved in the TGFβ1/Smad signaling pathway and might regulate the activation of Smad proteins. However, whether JNK is activated by TGFβ1 in rat peritoneal mesothelial cells (RPMCs) and the role taken by JNK signaling in EMT induced by TGFβ1 remains undetermined. In the present study, we investigated the role of JNK-Smad pathway in EMT induced by TGFβ1 in RPMCs.

⋄ Methods

We harvested RPMCs from the peritoneum of male Sprague-Dawley rats and then cultured the cells in Dulbecco modified Eagle medium / F12 medium with 15% (volume:volume) fetal bovine serum. The cells were pretreated with SP600125, a specific inhibitor of JNK, for 4 hours before incubation with TGFβ1. The protein expression levels of phosphorylated JNK, Smad2, and Smad3 were detected by Western blotting. The messenger RNA levels and protein expression of α-smooth muscle actin (α-SMA), E-cadherin, and collagen I were determined with reverse transcriptase polymerase chain reaction and Western blotting respectively.

⋄ Results

Expression of α-SMA and collagen I were significantly increased and expression of E-cadherin decreased with TGFβ1 in RPMCs. Transforming growth factor β1 can stimulate phosphorylated JNK expression from 5 minutes, with the peak at 10 minutes, and phosphorylated Smad2 and Smad3 expression from 10 minutes, with the peak at 30 minutes. The addition of SP600125, which blocked activation of JNK, effectively inhibited TGFβ1-induced phosphorylation of Smad3, but not Smad2. Also, our results showed that SP600125 effectively suppressed TGFβ1-induced high expression of α-SMA and collagen I, and prevented TGFβ1-induced downregulation of E-cadherin expression in RPMCs.

⋄ Conclusions

This study demonstrated that JNK signaling may play an important role in EMT induced by TGFβ1 in RPMCs through activation of Smad3, suggesting that JNK inhibitor may prove to be a novel therapeutic agent for peritoneal fibrosis.

Honokiol protects against epidural fibrosis by inhibiting fibroblast proliferation and extracellular matrix overproduction in rats post‑laminectomy

Epidural fibrosis (EF)‑induced failed back surgery syndrome (FBSS) in patients post‑laminectomy remains a medical challenge. Although the scarring mechanisms remain unclear, the majority of aetiological studies have reported fibroblast dysfunction. Honokiol, the major bioactive constituent of the magnolia tree, exerts a variety of pharmacological effects, including anti‑proliferative and anti‑fibrotic effects, on various cell types. The present study investigated whether honokiol attenuates EF progression. In vitro, it was found that honokiol inhibited excessive fibroblast proliferation induced by transforming growth factor‑β1 (TGF‑β1) and the synthesis of extracellular matrix (ECM) components, including fibronectin and type I collagen, in a dose‑dependent manner. These effects were attributed to the ability of honokiol to suppress the activity of connective tissue growth factor (CTGF), which is indispensable for the progression of fibrosis. Mechanistically, honokiol attenuated the TGF‑β1‑induced activation of the Smad2/3 and mitogen‑activated protein kinase (MAPK) signalling pathways in fibroblasts. In vivo, honokiol reduced the proliferation of fibroblasts and the synthesis of ECM components, thus ameliorating EF in a rat model post‑laminectomy. Taken together, these preclinical findings suggest that honokiol deserves further consideration as a candidate therapeutic agent for EF.

Targeting cardiac fibrosis in heart failure with preserved ejection fraction: mirage or miracle?

Cardiac fibrosis is central to the pathology of heart failure, particularly heart failure with preserved ejection fraction (HFpEF). Irrespective of the underlying profibrotic condition (e.g. ageing, diabetes, hypertension), maladaptive cardiac fibrosis is defined by the transformation of resident fibroblasts to matrix-secreting myofibroblasts. Numerous profibrotic factors have been identified at the molecular level (e.g. TGFβ, IL11, AngII), which activate gene expression programs for myofibroblast activation. A number of existing HF therapies indirectly target fibrotic pathways; however, despite multiple clinical trials in HFpEF, a specific clinically effective antifibrotic therapy remains elusive. Therapeutic inhibition of TGFβ, the master-regulator of fibrosis, has unfortunately proven toxic and ineffective in clinical trials to date, and new approaches are needed. In this review, we discuss the pathophysiology and clinical implications of interstitial fibrosis in HFpEF. We provide an overview of trials targeting fibrosis in HFpEF to date and discuss the promise of potential new therapeutic approaches and targets in the context of underlying molecular mechanisms.

GDF15, an update of the physiological and pathological roles it plays: a review

Growth differentiation factor 15 (GDF15) is a peptide hormone, and a divergent member of the transforming growth factor beta (TGFβ) superfamily. In normal physiology, GDF15 is expressed in multiple tissues at a low concentration. GDF15 is overexpressed during and following many pathological conditions such as tissue injury and inflammation in order to play a protective role. However, GDF15 appears to promote tumour growth in the later stages of malignant cancer. The recently identified endogenous receptor for GDF15, GDNF family receptor a-like (GFRAL), has allowed elucidation of a physiological pathway in which GDF15 regulates energy homeostasis and body weight, primarily via appetite suppression. The anorectic effect of GDF15 provides some therapeutic potential in management of cancer-related anorexia/cachexia and obesity. Despite the identification of GFRAL as a GDF15 receptor, there appears to be other signalling mechanisms utilized by GDF15 that further increase the possibility of development of therapeutic treatments, should these pathways be fully characterized. In this review, GDF15 function in both physiological and pathological conditions in various tissues will be discussed.

Hepatic Stellate Cells and Hepatocarcinogenesis

Hepatic stellate cells (HSCs) are a significant component of the hepatocellular carcinoma (HCC) tumor microenvironment (TME). Activated HSCs transform into myofibroblast-like cells to promote fibrosis in response to liver injury or chronic inflammation, leading to cirrhosis and HCC. The hepatic TME is comprised of cellular components, including activated HSCs, tumor-associated macrophages, endothelial cells, immune cells, and non-cellular components, such as growth factors, proteolytic enzymes and their inhibitors, and other extracellular matrix (ECM) proteins. Interactions between HCC cells and their microenvironment have become topics under active investigation. These interactions within the hepatic TME have the potential to drive carcinogenesis and create challenges in generating effective therapies. Current studies reveal potential mechanisms through which activated HSCs drive hepatocarcinogenesis utilizing matricellular proteins and paracrine crosstalk within the TME. Since activated HSCs are primary secretors of ECM proteins during liver injury and inflammation, they help promote fibrogenesis, infiltrate the HCC stroma, and contribute to HCC development. In this review, we examine several recent studies revealing the roles of HSCs and their clinical implications in the development of fibrosis and cirrhosis within the hepatic TME.

Role of Epithelial-Mesenchymal Transition in Retinal Pigment Epithelium Dysfunction

Retinal pigment epithelial (RPE) cells maintain the health and functional integrity of both photoreceptors and the choroidal vasculature. Loss of RPE differentiation has long been known to play a critical role in numerous retinal diseases, including inherited rod-cone degenerations, inherited macular degeneration, age-related macular degeneration, and proliferative vitreoretinopathy. Recent studies in post-mortem eyes have found upregulation of critical epithelial-mesenchymal transition (EMT) drivers such as TGF-β, Wnt, and Hippo. As RPE cells become less differentiated, they begin to exhibit the defining characteristics of mesenchymal cells, namely, the capacity to migrate and proliferate. A number of preclinical studies, including animal and cell culture experiments, also have shown that RPE cells undergo EMT. Taken together, these data suggest that RPE cells retain the reprogramming capacity to move along a continuum between polarized epithelial cells and mesenchymal cells. We propose that movement along this continuum toward a mesenchymal phenotype be defined as RPE Dysfunction. Potential mechanisms include impaired tight junctions, accumulation of misfolded proteins and dysregulation of several key pathways and molecules, such as TGF-β pathway, Wnt pathway, nicotinamide, microRNA 204/211 and extracellular vesicles. This review synthesizes the evidence implicating EMT of RPE cells in post-mortem eyes, animal studies, primary RPE, iPSC-RPE and ARPE-19 cell lines.

RIPK3: A New Player in Renal Fibrosis

Chronic kidney disease (CKD) is the end result of a plethora of renal insults, including repeated episodes of acute or toxic kidney injury, glomerular, or diabetic kidney disease. It affects a large number of the population worldwide, resulting in significant personal morbidity and mortality and economic cost to the community. Hence it is appropriate to focus on treatment strategies that interrupt the development of kidney fibrosis, the end result of all forms of CKD, in addition to upstream factors that may be specific to certain diseases. However, the current clinical approach to prevent or manage renal fibrosis remains unsatisfactory. The rising importance of receptor-interacting serine/threonine-protein kinase (RIPK) 3 in the inflammatory response and TGF-β1 signaling is increasingly recognized. We discuss here the biological functions of RIPK3 and its role in the development of renal fibrosis.

TGF-β and WNT signaling pathways in cardiac fibrosis: non-coding RNAs come into focus

Cardiac fibrosis describes the inappropriate proliferation of cardiac fibroblasts (CFs), leading to accumulation of extracellular matrix (ECM) proteins in the cardiac muscle, which is found in many pathophysiological heart conditions. A range of molecular components and cellular pathways, have been implicated in its pathogenesis. In this review, we focus on the TGF-β and WNT signaling pathways, and their mutual interaction, which have emerged as important factors involved in cardiac pathophysiology. The molecular and cellular processes involved in the initiation and progression of cardiac fibrosis are summarized. We focus on TGF-β and WNT signaling in cardiac fibrosis, ECM production, and myofibroblast transformation. Non-coding RNAs (ncRNAs) are one of the main players in the regulation of multiple pathways and cellular processes. MicroRNAs, long non-coding RNAs, and circular long non-coding RNAs can all interact with the TGF-β/WNT signaling axis to affect cardiac fibrosis. A better understanding of these processes may lead to new approaches for diagnosis and treatment of many cardiac conditions. Video Abstract.

Loss of epithelial AR increase castration resistant stem-like prostate cancer cells and promotes cancer metastasis via TGF-β1/EMT pathway

Background

Previous study has reported that loss of epithelial androgen receptor (AR) may promote tumor progression and cause TRAMP mouse model die earlier. The detail mechanisms, however, remain unclear.

Methods

Immunohistochemistry assay, Western blot and real-time PCR were used to detect the expression of epithelial and mesenchymal markers. RNA extraction, RT-PCR, quantitative RT-PCR, BrdU incorporation assays, flow cytometry and other experimental technics were also used in present work.

Results

Decreased expression of epithelial markers (Cytokeratin 8, NKX3.1 and E-cadherin) and increased expression of mesenchymal markers (α-SMA, Vimentin, and N-cadherin) in were found in AR knockout TRAMP tumors. Further investigation indicated that AR signal deprivation is associated with cell morphology transition, high cell mobility, high cell invasion rate and resistance to anoikis in TRAMP prostate tumor cells. Together, these findings implied knockout AR in TRAMP prostate tumor may lead to EMT, which may result in earlier metastasis, and then cause TRAMP mice die earlier. TGF-β1 is responsible for EMT in AR knockout TRAMP tumor cells.

Conclusions

In conclusion, ADT therapy induced hormone refractory prostate cancer may gain the ability of metastasis through cell’s EMT which is a phase of poor differentiation. Anti-EMT drugs should be developed to battle the tumor metastasis induced by ADT therapy.

Canonical signaling by TGF family members in mesenchymal stromal cells is dispensable for hematopoietic niche maintenance under basal and stress conditions

Mesenchymal stromal cells are an important component of the bone marrow hematopoietic niche. Prior studies showed that signaling from members of the transforming growth factor (TGF) superfamily in mesenchymal stromal cells is required for normal niche development. Here, we assessed the impact of TGF family signaling on niche maintenance and stress responses by deleting Smad4 in mesenchymal stromal cells at birth, thereby abrogating canonical TGF signaling. No alteration in the number or spatial organization of CXCL12-abundant reticular (CAR) cells, osteoblasts, or adipocytes was observed in Osx-Cre, Smad4^fl/fl mice, and expression of key niche factors was normal. Basal hematopoiesis and stress erythropoiesis responses to acute hemolytic anemia were normal. TGF-β potently inhibits stromal CXCL12 expression in vitro; however, G-CSF induced decreases in bone marrow CXCL12 expression and subsequent hematopoietic stem/progenitor cell mobilization were normal in Osx-Cre, Tgfbr2^fl/fl mice, in which all TGF-β signaling in mesenchymal stromal is lost. Finally, although a prior study showed that TGF-β enhances recovery from myeloablative therapy, hematopoietic recovery following single or multiple doses of 5-flurauracil were normal in Osx-Cre, Tgfbr2^fl/fl mice. Collectively, these data suggest that TGF family member signaling in mesenchymal stromal cells is dispensable for hematopoietic niche maintenance under basal and stress conditions.

LncRNA GAS5 attenuates fibroblast activation through inhibiting Smad3 signaling

Transforming growth factor-β (TGF-β)-induced fibroblast activation is a key pathological event during tissue fibrosis. Long noncoding RNA (lncRNA) is a class of versatile gene regulators participating in various cellular and molecular processes. However, the function of lncRNA in fibroblast activation is still poorly understood. In this study, we identified growth arrest-specific transcript 5 (GAS5) as a novel regulator for TGF-β-induced fibroblast activation. GAS5 expression was downregulated in cultured fibroblasts by TGF-β and in resident fibroblasts from bleomycin-treated skin tissues. Overexpression of GAS5 suppressed TGF-β-induced fibroblast to myofibroblast differentiation. Mechanistically, GAS5 directly bound mothers against decapentaplegic homolog 3 (Smad3) and promoted Smad3 binding to Protein phosphatase 1A (PPM1A), a Smad3 dephosphatase, and thus accelerated Smad3 dephosphorylation in TGF-β-treated fibroblasts. In addition, GAS5 inhibited fibroblast proliferation. Importantly, local delivery of GAS5 via adenoviral vector suppressed bleomycin-induced skin fibrosis in mice. Collectively, our data revealed that GAS5 suppresses fibroblast activation and fibrogenesis through inhibiting TGF-β/Smad3 signaling, which provides a rationale for an lncRNA-based therapy to treat fibrotic diseases.

Targeting Hepatic Stellate Cells for the Treatment of Liver Fibrosis by Natural Products: Is It the Dawning of a New Era?

Liver fibrosis is a progressive liver damage condition that is worth studying widely. It is important to target and alleviate the disease at an early stage before turning into later cirrhosis or liver cancer. There are currently no direct medicines targeting the attenuation or reversal of liver fibrosis, and so there is an urgent need to look into this area. Traditional Chinese Medicine has a long history in using herbal medicines to treat liver diseases including fibrosis. It is time to integrate the ancient wisdom with modern science and technology to look for the best solution to the disease. In this review, the principal concept of the pathology of liver fibrosis will be described, and then some of the single compounds isolated from herbal medicines, including salvianolic acids, oxymatrine, curcumin, tetrandrine, etc. will be discussed from their effects to the molecular mechanism behind. Molecular targets of the compounds are analyzed by network pharmacology approach, and TGFβ/SMAD was identified as the most common pathway. This review serves to summarize the current findings of herbal medicines combining with modern medicines in the area of fibrosis. It hopefully provides insights in further pharmaceutical research directions.

EX-527 Prevents the Progression of High-Fat Diet-Induced Hepatic Steatosis and Fibrosis by Upregulating SIRT4 in Zucker Rats

Sirtuin (SIRT) is known to prevent nonalcoholic fatty liver disease (NAFLD); however, the role of SIRT4 in the progression of hepatic fibrosis remains unknown. We hypothesize that EX-527, a selective SIRT1 inhibitor, can inhibit the progression of high-fat diet (HFD)-induced hepatic fibrosis. We found that SIRT4 expression in the liver of NAFLD patients is significantly lower than that in normal subjects. In this study, EX-527 (5 µg/kg), administered to HFD rats twice a week for ten weeks, reduced the serum levels of triglyceride (TG), total cholesterol, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) and attenuated hepatic fibrosis evidenced by Masson’s trichrome and hepatic fat by oil red-O staining. EX-527 upregulated SIRT2, SIRT3, and SIRT4 expression in the liver of HFD fed rats but downregulated transforming growth factor-β1 (TGF-β1) and α-smooth muscle actin (α-SMA) expression. It decreased proinflammatory cytokine production and hydroxyproline levels in the serum and SMAD4 expression and restored apoptotic protein (Bcl-2, Bax, and cleaved caspase-3) expression. These data propose a critical role for the SIRT4/SMAD4 axis in hepatic fibrogenesis. SIRT4 upregulation has the potential to counter HFD-induced lipid accumulation, inflammation, and fibrogenesis. We demonstrate that EX-527 is a promising candidate in inhibiting the progression of HFD-induced liver fibrosis.

TGF-β Signaling

Transforming growth factor-β (TGF-β) represents an evolutionarily conserved family of secreted polypeptide factors that regulate many aspects of physiological embryogenesis and adult tissue homeostasis. The TGF-β family members are also involved in pathophysiological mechanisms that underlie many diseases. Although the family comprises many factors, which exhibit cell type-specific and developmental stage-dependent biological actions, they all signal via conserved signaling pathways. The signaling mechanisms of the TGF-β family are controlled at the extracellular level, where ligand secretion, deposition to the extracellular matrix and activation prior to signaling play important roles. At the plasma membrane level, TGF-βs associate with receptor kinases that mediate phosphorylation-dependent signaling to downstream mediators, mainly the SMAD proteins, and mediate oligomerization-dependent signaling to ubiquitin ligases and intracellular protein kinases. The interplay between SMADs and other signaling proteins mediate regulatory signals that control expression of target genes, RNA processing at multiple levels, mRNA translation and nuclear or cytoplasmic protein regulation. This article emphasizes signaling mechanisms and the importance of biochemical control in executing biological functions by the prototype member of the family, TGF-β.

Age- and sex-dependent differences in extracellular matrix metabolism associate with cardiac functional and structural changes

Age-related remodeling of the heart causes structural and functional changes in the left ventricle (LV) that are associated with a high index of morbidities and mortality worldwide. Some cardiac pathologies in the elderly population vary between genders revealing that cardiac remodeling during aging may be sex-dependent. Herein, we analyzed the effects of cardiac aging in male and female C57Bl/6 mice in four age groups, 3, 6, 12, and 18 month old (n = 6-12 animals/sex/age), to elucidate which age-related characteristics of LV remodeling are sex-specific. We focused particularly in parameters associated with age-dependent remodeling of the LV extracellular matrix (ECM) that are involved in collagen metabolism. LV function and anatomical structure were assessed both by conventional echocardiography and speckle tracking echocardiography (STE). We then measured ECM proteins that directly affect LV contractility and remodeling. All data were analyzed across ages and between sexes and were directly linked to LV functional changes. Echocardiography confirmed an age-dependent decrease in chamber volumes and LV internal diameters, indicative of concentric remodeling. As in humans, animals displayed preserved ejection fraction with age. Notably, changes to chamber dimensions and volumes were temporally distinct between sexes. Complementary to the traditional echocardiography, STE revealed that circumferential strain rate declined in 18 month old females, compared to younger animals, but not in males, suggesting STE as an earlier indicator for changes in cardiac function between sexes. Age-dependent collagen deposition and expression in the endocardium did not differ between sexes; however, other factors involved in collagen metabolism were sex-specific. Specifically, while decorin, osteopontin, Cthrc1, and Ddr1 expression were age-dependent but sex-independent, periostin, lysyl oxidase, and Mrc2 displayed age-dependent and sex-specific differences. Moreover, our data also suggest that with age males and females have distinct TGFβ signaling pathways. Overall, our results give evidence of sex-specific molecular changes during physiological cardiac remodeling that associate with age-dependent structural and functional dysfunction. These data highlight the importance of including sex-differences analysis when studying cardiac aging.