SnoN as a novel negative regulator of TGF-β/Smad signaling: a target for tailoring organ fibrosis

LP340, a novel histone deacetylase inhibitor, decreases liver injury and fibrosis in mice: role of oxidative stress and microRNA-23a

Effective therapy for liver fibrosis is lacking. Here, we examined whether LP340, the lead candidate of a new-generation of hydrazide-based HDAC1,2,3 inhibitors (HDACi), decreases liver fibrosis. Liver fibrosis was induced by CCl4 treatment and bile duct ligation (BDL) in mice. At 6 weeks after CCl4, serum alanine aminotransferase increased, and necrotic cell death and leukocyte infiltration occurred in the liver. Tumor necrosis factor-α and myeloperoxidase markedly increased, indicating inflammation. After 6 weeks, α-smooth muscle actin (αSMA) and collagen-1 expression increased by 80% and 575%, respectively, indicating hepatic stellate cell (HSC) activation and fibrogenesis. Fibrosis detected by trichrome and Sirius-red staining occurred primarily in pericentral regions with some bridging fibrosis in liver sections. 4-Hydroxynonenal adducts (indicator of oxidative stress), profibrotic cytokine transforming growth factor-β (TGFβ), and TGFβ downstream signaling molecules phospho-Smad2/3 also markedly increased. LP340 attenuated indices of liver injury, inflammation, and fibrosis markedly. Moreover, Ski-related novel protein-N (SnoN), an endogenous inhibitor of TGFβ signaling, decreased, whereas SnoN expression suppressor microRNA-23a (miR23a) increased markedly. LP340 (0.05 mg/kg, ig., daily during the last 2 weeks of CCl4 treatment) decreased 4-hydroxynonenal adducts and miR23a production, blunted SnoN decreases, and inhibited the TGFβ/Smad signaling. By contrast, LP340 had no effect on matrix metalloproteinase-9 expression. LP340 increased histone-3 acetylation but not tubulin acetylation, indicating that LP340 inhibited Class-I but not Class-II HDAC in vivo. After BDL, focal necrosis, inflammation, ductular reactions, and portal and bridging fibrosis occurred at 2 weeks, and αSMA and collagen-1 expression increased by 256% and 560%, respectively. LP340 attenuated liver injury, ductular reactions, inflammation, and liver fibrosis. LP340 also decreased 4-hydroxynonenal adducts and miR23a production, prevented SnoN decreases, and inhibited the TGFβ/Smad signaling after BDL. In vitro, LP340 inhibited immortal human hepatic stellate cells (hTERT-HSC) activation in culture (αSMA and collagen-1 expression) as well as miR23a production, demonstrating its direct inhibitory effects on HSC. In conclusions, LP340 is a promising therapy for both portal and pericentral liver fibrosis, and it works by inhibiting oxidative stress and decreasing miR23a.

Bone marrow mesenchymal stem cell transplantation alleviates radiation-induced myocardial fibrosis through inhibition of the TGF-β1/Smad2/3 signaling pathway in rabbit model

Background

and purpose: Radiotherapy (RT) is an effective treatment for most malignant chest tumors. However, radiation-induced myocardial fibrosis (RIMF) is a serious side effect of RT. Currently, due to the mechanism of RIMF has not been fully elucidated, there is a lack of effective therapeutic approach. In this study, we aimed to investigate the role and possible mechanisms of bone marrow mesenchymal stem cells (BMSCs) in the therapy of RIMF.

Materials and methods

Twenty-four New Zealand white rabbits were allotted into four groups (n = 6). Rabbits in the Control group received neither irradiation nor treatment. A single dose of 20 Gy heart X-irradiation was applied to the RT group, RT + PBS group and RT + BMSCs group. Rabbits in the RT + PBS group and RT + BMSCs group were injected with 200 μL PBS or 2 × 10⁶ cells via pericardium puncture 24 h following irradiation, respectively. Echocardiography was used to test the cardiac function; Then the heart samples were collected, and processed for histopathological, Western blot and immunohistochemistry investigations.

Results

It was observed that BMSCs have therapeutic effect on RIMF. Compared with the Control group, inflammatory mediators, oxidative stress and apoptosis were significantly increased, meanwhile, cardiac function was remarkably decreased in the RT group and RT + PBS group. However, in the BMSCs group, BMSCs significantly improved cardiac function, decreased inflammatory mediators, oxidative stress and apoptosis. Furthermore, BMSCs remarkably reduced the expression level of TGF-β1 and the phosphorylated-Smad2/3.

Conclusions

In conclusion, our research indicates BMSCs have the potential to alleviate RIMF through TGF-β1/Smad2/3 and would be a new therapeutic approach for patients with myocardial fibrosis.

ESRRB Inhibits the TGFβ Signaling Pathway to Drive Cell Proliferation in Cervical Cancer

Estrogen-related receptor β (ESRRB) is a member of the orphan nuclear receptor family and mediates stem cell self-renewal and early embryonic development. Previous studies have also reported that ESRRB plays a role in the development and progression of breast cancer and prostate cancer. In this study, we observed that ESRRB was highly expressed in cervical cancer and was associated with disease progression. Knocking out ESRRB using CRISPR/Cas9 gene editing in cervical cancer cells induced cell-cycle arrest at the transition from the G0-G1 phase to the S phase, resulting in inhibition of cell proliferation in vitro and reduced tumor growth in vivo. Conversely, ectopic expression of ESRRB significantly promoted the proliferation of cervical cancer cells. ESRRB activated transcription of SMAD7, a TGFβ pathway inhibitor, which blocked phosphorylation and nuclear translocation of SMAD2/3 to the nucleus, thereby downregulating CDKN1A and upregulating CCNA2 and MYC. In turn, MYC transactivated ESRRB and upregulated SMAD7, thus forming a positive feedback loop with ESRRB. Together, these findings identify the tumor-promoting function of ESRRB in cervical cancer and reveal a mechanism by which ESRRB stimulates cell proliferation to promote cancer progression.

SIGNIFICANCE

The ESRRB/SMAD7/MYC-positive feedback loop inhibits TGFβ signaling to activate cell-cycle progression and promote proliferation in cervical cancer, thereby driving tumor growth.

N-butyldeoxynojirimycin (miglustat) ameliorates pulmonary fibrosis through inhibition of nuclear translocation of Smad2/3

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease. The disease involves excessive accumulation of fibroblasts and myofibroblasts, and myofibroblasts differentiated by pro-fibrotic factors promote the deposition of extracellular matrix proteins such as collagen and fibronectin. Transforming growth factor-β1 is a pro-fibrotic factor that promotes fibroblast-to-myofibroblast differentiation (FMD). Therefore, inhibition of FMD may be an effective strategy for IPF treatment. In this study, we screened the anti-FMD effects of various iminosugars and showed that some compounds, including N-butyldeoxynojirimycin (NB-DNJ, miglustat, an inhibitor of glucosylceramide synthase (GCS)), a clinically approved drug for treating Niemann-Pick disease type C and Gaucher disease type 1, inhibited TGF-β1-induced FMD by inhibiting the nuclear translocation of Smad2/3. N-butyldeoxygalactonojirimycin having GCS inhibitory effect did not attenuate the TGF-β1-induced FMD, suggesting that NB-DNJ exerts the anti-FMD effects by GCS inhibitory effect independent manner. N-butyldeoxynojirimycin did not inhibit TGF-β1-induced Smad2/3 phosphorylation. In a mouse model of bleomycin (BLM)-induced pulmonary fibrosis, intratracheal or oral administration of NB-DNJ at an early fibrotic stage markedly ameliorated lung injury and deterioration of respiratory functions, such as specific airway resistance, tidal volume, and peak expiratory flow. Furthermore, the anti-fibrotic effects of NB-DNJ in the BLM-induced lung injury model were similar to those of pirfenidone and nintedanib, which are clinically approved drugs for the treatment of IPF. These results suggest that NB-DNJ may be effective for IPF treatment.

SB431542 alleviates lupus nephritis by regulating B cells and inhibiting the TLR9/TGFβ1/PDGFB signaling

Lupus nephritis (LN) is the most common cause of morbidity and mortality in patients with systemic lupus erythematosus (SLE). Currently, immunosuppressive treatments for LN are suboptimal and can induce significant side effects. SB431542 is a selective and potent inhibitor of the TGFβ/Activin/NODAL pathway. Here, we study the effects of SB431542 treatment on LN and discuss the potential mechanisms. SB431542 ameliorated clinical outcomes with a consequent histological improvement in NZB/W mice. A comparative transcriptional profiling analysis revealed 586 differentially expressed genes (247 downregulated genes) in the SB431542 group compared to the control group. We found that the downregulated genes were mainly enriched in the biological processes of B cell activation, B cell proliferation, B cell differentiation, and B cell receptor signaling. Kyoto encyclopedia of genes and genomes pathway analysis revealed that the hematopoietic cell linage pathway was significantly downregulated in the SB431542 group. In addition, we observed that SB431542 reduced the splenic or renal levels of CD20 and the serum levels of anti-dsDNA antibody (IgG) in NZB/W mice. Furthermore, qRT-PCR and immunohistochemistry confirmed that SB431542 inhibits the production of TLR9, TGFβ1, and PDGFB. Thus, due to its immunomodulatory activities, SB431542 could be considered for clinical therapy development for LN.

Combination Therapy of Alpha-Lipoic Acid, Gliclazide and Ramipril Protects Against Development of Diabetic Cardiomyopathy via Inhibition of TGF-β/Smad Pathway

Background: Diabetic cardiomyopathy (DCM) is a major long-term complication of diabetes mellitus, accounting for over 20% of annual mortality rate of diabetic patients globally. Although several existing anti-diabetic drugs have improved glycemic status in diabetic patients, prevalence of DCM is still high. This study investigates cardiac effect of alpha-lipoic acid (ALA) supplementation of anti-diabetic therapy in experimental DCM. Methods: Following 12 h of overnight fasting, 44 male Sprague Dawley rats were randomly assigned to two groups of healthy control (n = 7) and diabetic (n = 37) groups, and fasting blood glucose was measured. Type 2 diabetes mellitus (T2DM) was induced in diabetic group by intraperitoneal (i.p.) administration of nicotinamide (110 mg/kg) and streptozotocin (55 mg/kg). After confirmation of T2DM on day 3, diabetic rats received monotherapies with ALA (60 mg/kg; n = 7), gliclazide (15 mg/kg; n = 7), ramipril (10 mg/kg; n = 7) or combination of the three drugs (n = 7) for 6 weeks while untreated diabetic rats received distilled water and were used as diabetic control (n = 9). Rats were then sacrificed, and blood, pancreas and heart tissues were harvested for analyses using standard methods. Results: T2DM induction caused pancreatic islet destruction, hyperglycemia, weight loss, high relative heart weight, and development of DCM, which was characterized by myocardial degeneration and vacuolation, cardiac fibrosis, elevated cardiac damage markers (plasma and cardiac creatine kinase-myocardial band, brain natriuretic peptide and cardiac troponin I). Triple combination therapy of ALA, gliclazide and ramipril preserved islet structure, maintained body weight and blood glucose level, and prevented DCM development compared to diabetic control (p < 0.001). In addition, the combination therapy markedly reduced plasma levels of inflammatory markers (IL-1β, IL-6 and TNF-α), plasma and cardiac tissue malondialdehyde, triglycerides and total cholesterol while significantly increasing cardiac glutathione and superoxide dismutase activity and high-density lipoprotein-cholesterol compared to diabetic control (p < 0.001). Mechanistically, induction of T2DM upregulated cardiac expression of TGF-β1, phosphorylated Smad2 and Smad3 proteins, which were downregulated following triple combination therapy (p < 0.001). Conclusion: Triple combination therapy of ALA, gliclazide and ramipril prevented DCM development by inhibiting TGF-β1/Smad pathway. Our findings can be extrapolated to the human heart, which would provide effective additional pharmacological therapy against DCM in T2DM patients.

BMP-7 ameliorates partial epithelial-mesenchymal transition by restoring SnoN protein level via Smad1/5 pathway in diabetic kidney disease

Tubulointerstitial fibrosis (TIF) is involved in the development of diabetic kidney disease (DKD). Transforming growth factor β1 (TGF-β1) is involved in the extensive fibrosis of renal tissue by facilitating the partial epithelial-mesenchymal transition (EMT), increasing the synthesis of extracellular matrix (ECM), inhibiting degradation, inducing apoptosis of renal parenchyma cells, and activating renal interstitial fibroblasts and inflammatory cells. Recent studies indicated that bone morphogenetic protein-7 (BMP-7) upregulated the expression of endogenous SnoN against renal TIF induced by TGF-β1 or hyperglycemia. Nevertheless, the mechanisms underlying the BMP-7-mediated restoration of SnoN protein level remains elusive. The present study demonstrated the increased expression of BMP-7 in diabetic mellitus (DM) mice by hydrodynamic tail vein injection of overexpressed BMP-7 plasmid, which attenuated the effects of DM on kidney in mice. Partial tubular EMT and the accumulation of Collagen-III were resisted in DM mice that received overexpressed BMP-7 plasmid. Similar in vivo results showed that BMP-7 was competent to alleviate NRK-52E cells undergoing partial EMT in a high-glucose milieu. Furthermore, exogenous BMP-7 activated the Smad1/5 pathway to promote gene transcription of SnoN and intervened ubiquitination of SnoN; both effects repaired the SnoN protein level in renal tubular cells and kidney tissues of DM mice. Therefore, these findings suggested that BMP-7 could upregulate SnoN mRNA and protein levels by activating the classical Smad1/5 pathway to refrain from the partial EMT of renal tubular epithelial cells and the deposition of ECM in DKD-induced renal fibrosis.

Regulation of transforming growth factor-β signalling by SUMOylation and its role in fibrosis

Fibrosis is an abnormal healing process that only repairs the structure of an organ after injury and does not address damaged functions. The pathogenesis of fibrosis is multifactorial and highly complex; numerous signalling pathways are involved in this process, with the transforming growth factor-β (TGF-β) signalling pathway playing a central role. TGF-β regulates the generation of myofibroblasts and the epithelial-mesenchymal transition by regulating transcription and translation of downstream genes and precisely regulating fibrogenesis. The TGF-β signalling pathway can be modulated by various post-translational modifications, of which SUMOylation has been shown to play a key role. In this review, we focus on the function of SUMOylation in canonical and non-canonical TGF-β signalling and its role in fibrosis, providing promising therapeutic strategies for fibrosis.

Blood glucose control contributes to protein stability of Ski-related novel protein N in a rat model of diabetes

Ski-related novel protein N (SnoN) negatively regulates the transforming growth factor-β1 (TGF-β1)/Smads signaling pathway and is present at a low level during diabetic nephropathy (DN), but its underlying regulatory mechanism is currently unknown. The present study aimed to assess the effects of insulin-controlled blood glucose on renal SnoN expression and fibrosis in rats with diabetes mellitus (DM). Streptozotocin-induced DM rats were treated with insulin glargine (INS group) following successful model establishment. Blood samples were collected and centrifuged for biochemical indexes and the kidneys were collected for morphological analysis. In vitro, rat renal proximal tubular epithelial cells were treated with high-glucose medium for 24 h and transferred to normal glucose medium for 24 h. The expression levels of TGF-β1, SnoN, Smad ubiquitin regulatory factor 2 (Smurf2), Arkadia, Smads, E-cadherin, α-smooth muscle actin and collagen III were assessed by western blotting and immunohistochemistry. The ubiquitylation of SnoN was detected by immunoprecipitation, and the expression levels of SnoN mRNA were evaluated by reverse transcription-quantitative PCR. The biochemical parameters and morphology indicated that renal fibrosis was notable in the DM group and mitigated in the INS group. Compared with the control group, TGF-β1, phosphor (p)-Smad2, p-Smad3, Smurf2 and Arkadia levels were enhanced in the DM group, and the levels of SnoN protein were decreased, whereas the levels of SnoN mRNA and ubiquitylation were increased in renal tissues. Notably, treatment with insulin reversed this trend. Furthermore, changing the glucose levels in the medium from high to normal glucose suppressed the epithelial-mesenchymal transition of NRK-52E cells by restoring the SnoN protein levels, and this phenomenon was impaired by the knockout of SnoN. SnoN protein levels were likely reduced through a mechanism enhanced by the ubiquitin proteasome system, which reversed the transcriptional activation of SnoN during DN progression. In addition, controlling blood glucose may delay DN fibrosis by rescuing the protein stability of SnoN.

Promoting roles of KLF5 in myocardial infarction in mice involving microRNA-27a suppression and the following GFPT2/TGF-β/Smad2/3 axis activation

Myocardial infarction (MI) is a major atherosclerotic cardiovascular disease which represents a leading cause of death worldwide. Kruppel-like factor 5 (KLF5) is a member of the kruppel-like transcription factor family which has been reported with pro-apoptotic functions in myocardial cells. This work focuses on the function of KLF5 in the pathogenesis of MI and the molecules involved. A mouse model with MI was established. Hypoxia/reoxygenation (H/R)-treated H9C2 cells were applied for in vitro experiments. A KLF5-specific inhibitor ML264 was administrated in cell and animal models. ML264 significantly reduced apoptosis, expression of fibrosis-related markers, reactive oxygen species in the H/R-treated H9C2 cells, and it reduced myocardial injury, infarct size, apoptosis and fibrosis in the myocardial tissues in model mice through specific downregulation of KLF5. A microRNA (miRNA) microarray analysis was performed, which suggested miR-27a as the most upregulated miRNA in the H/R-treated cells after ML264 treatment. miR-27a mimic reduced apoptosis and fibrosis in H/R-treated cells, while miR-27a inhibition blocked the protective roles of ML264. The integrated bioinformatic analyses and luciferase assays confirmed glutamine fructose-6-phosphate transaminase 2 (GFPT2) mRNA as a target of miR-27a. Overexpression of GFPT2 counteracted the protective functions of miR-27a against MI through the activation of the TGF-β/Smad2/3 signaling pathway. To conclude, this study evidenced that KLF5 possibly induces cell and tissue damage in MI through downregulation of miR-27a and the subsequent activation of GFPT2/TGF-β/Smad2/3 axis. This study may offer novel thoughts into MI treatment.

The Ubiquitin Proteasome System and Skin Fibrosis

The ubiquitin proteasome system (UPS) is a highly conserved way to regulate protein turnover in cells. The UPS hydrolyzes and destroys variant or misfolded proteins and finely regulates proteins involved in differentiation, apoptosis, and other biological processes. This system is a key regulatory factor in the proliferation, differentiation, and collagen secretion of skin fibroblasts. E3 ubiquitin protein ligases Parkin and NEDD4 regulate multiple signaling pathways in keloid. Tumor necrosis factor (TNF) receptor-associated factor 4 (TRAF4) binding with deubiquitinase USP10 can induce p53 destabilization and promote keloid-derived fibroblast proliferation. The UPS participates in the occurrence and development of hypertrophic scars by regulating the transforming growth factor (TGF)-β/Smad signaling pathway. An initial study suggests that TNFα-induced protein 3 (TNFAIP3) polymorphisms may be significantly associated with scleroderma susceptibility in individuals of Caucasian descent. Sumoylation and multiple ubiquitin ligases, including Smurfs, UFD2, and KLHL42, play vital roles in scleroderma by targeting the TGF-β/Smad signaling pathway. In the future, drugs targeting E3 ligases and deubiquitinating enzymes have great potential for the treatment of skin fibrosis.

Naringin attenuates renal interstitial fibrosis by regulating the TGF-β/Smad signaling pathway and inflammation

Interstitial fibrosis is a typical feature of all progressive renal diseases. The process of fibrosis is frequently coupled with the presence of pro-fibrotic factors and inflammation. Naringin is a dihydroflavone compound that has been previously reported to exhibit anti-fibrotic effects in the liver, where it prevents oxidative damage. In the present study, a rat model of renal interstitial fibrosis and fibrosis cell model were established to evaluate the effects of naringin on inflammatory proteins and fibrosis markers in kidney of rats and NRK-52E cells, and to elucidate the role of the TGF-β/Smad signaling pathway in this mechanism. Compared with those in fibrotic NRK-52E cells that were stimulated by transforming growth factor-β (TGF-β), gene expression levels of α-smooth muscle actin (α-SMA), collagen 1 (COL1A1), collagen 3 (COL3A1), interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) were all found to be significantly decreased in fibrotic NRK-52E cells following treatment with naringin (50, 100 and 200 ng/ml). Results from the histopathological studies showed that naringin treatment preserved the renal tissue structure and reduced the degree of fibrosis in the kidney tissues of rats that underwent unilateral ureteral obstruction (UUO). In addition, naringin administration reduced the expression of α-SMA, COL1A1, COL3A1, IL-1β, IL-6 and TNF-α in the kidneys of rats following UUO. The current study, using western blot analysis, indicated that naringin also downregulated the activation of Smad2/3 and the expression of Smad4, high-mobility group protein B1, activator protein-1, NF-κB and cyclooxygenase-2 whilst upregulating the expression of Smad7 in fibrotic NRK-52E cells and rats in the UUO group. In conclusion, naringin could antagonize renal interstitial fibrosis by regulating the TGF-β/Smad pathway and the expression of inflammatory factors.

Transforming growth factor-β in tissue fibrosis

TGF-β is extensively implicated in the pathogenesis of fibrosis. In fibrotic lesions, spatially restricted generation of bioactive TGF-β from latent stores requires the cooperation of proteases, integrins, and specialized extracellular matrix molecules. Although fibroblasts are major targets of TGF-β, some fibrogenic actions may reflect activation of other cell types, including macrophages, epithelial cells, and vascular cells. TGF-β–driven fibrosis is mediated through Smad-dependent or non-Smad pathways and is modulated by coreceptors and by interacting networks. This review discusses the role of TGF-β in fibrosis, highlighting mechanisms of TGF-β activation and signaling, the cellular targets of TGF-β actions, and the challenges of therapeutic translation.

Smad2 and Smad3 play antagonistic roles in high glucose-induced renal tubular fibrosis via the regulation of SnoN

Diabetic nephropathy (DN) is a serious microvascular complication of diabetes mellitus.The main pathological features of DN include glomerular sclerosis and renal tubular interstitial fibrosis, which results in epithelial mesenchymal transition (EMT) and excessive extracellular matrix (ECM) deposition.Transforming growth factor-β1(TGF-β1) is a critical factor that regulates the manifestation of renal fibrosis.Smad2 and Smad3 are the main downstream of the TGF-β1 pathway. Ski-related novel protein N(SnoN) is a negative regulator of TGF-β1, and inhibits the activation of the TGF-β1/Smad2/3 signalling pathway. In this study, the expression of Smad2 and Smad3 proteins, SnoN mRNA, SnoN proteins, and the ubiquitination levels of SnoN were determined in DN rats and renal tubular epithelial cells(NRK52E cells). Knockdown and overexpression of Smad2 or Smad3 in NRK52E cells were used to investigate the specific roles of Smad2 and Smad3 in the development of high glucose-induced renal tubular fibrosis, with a specific focus on their effect on the regulation of SnoN expression. Our study demonstrated that Smad3 could inhibit SnoN expression and increase ECM deposition in NRK52E cells, to promote high glucose-induced renal tubular fibrosis. In contrast, Smad2 could induce SnoN expression and reduce ECM deposition, to inhibit high glucose-induced fibrosis. The underlying mechanism involves regulation of SnoN expression. These findings provide a novel mechanism to understanding the significant role of the TGF-β1/ Smad2/3 pathway in DN.

SnoN residue (1-366) attenuates hypertrophic scars through resistance to transforming growth factor-β1-induced degradation

Hypertrophic scars (HSs) are characterized by fibroblast hyperproliferation and excessive matrix deposition. During wound healing, transforming growth factor (TGF)-β1/Smad signaling acts as a key regulator. As a transcriptional corepressor of TGF-β1/Smads, SnoN is expressed at low levels in many fibrotic diseases due to TGF-β1/Smad-induced degradation. SnoN residue (1-366; SR) is resistant to TGF-β1-induced degradation. However, the expression and role of SR in HSs are unknown. Here, we inhibited TGF-β1/Smad signaling via overexpression of SR to block fibroblast transdifferentiation, proliferation, and collagen deposition during HS formation. Our results showed that SnoN was downregulated in HS fibroblasts (HSFs) owing to TGF-β1/Smad-induced degradation. Overexpression of SR in normal human dermal fibroblasts (NHDFs) and HSFs successfully blocked phosphorylation of Smad2 and Smad3, thereby inhibiting NHDF transdifferentiation and HSF proliferation and reducing type I collagen (ColI) and type III collagen (ColIII) production and secretion. In addition, we applied overexpressed full-length SnoN (SF) and SR to wound granulation tissue in a rabbit model of HSs. SR reduced wound scarring, improved collagen deposition and arrangement of scar tissue, and decreased mRNA and protein expression of ColI, ColIII, and α-smooth muscle actin (α-SMA) more effectively than SF in vivo. These results suggest that SR could be a promising therapy for the prevention of HS.

Recent Advances in Understanding FOXN3 in Breast Cancer, and Other Malignancies

FOXN3 (forkhead box N3; CHES1: check point suppressor 1) belongs to the forkhead box (FOX) protein family. FOXN3 displays transcriptional inhibitory activity, and is involved in cell cycle regulation and tumorigenesis. FOXN3 is a tumor suppresser and alterations in FOXN3 are found in of a variety of cancers including melanoma, osteosarcoma, and hepatocellular carcinoma. While the roles of FOXN3 role in some cancers have been explored, its role in breast cancer remains unclear. Here we describe current state of knowledge of FOXN3 functions, and focus on its roles (known and potential) in breast cancer.

TAK1 may promote the development of diabetic nephropathy by reducing the stability of SnoN protein

AIMS

This study aimed to investigate the role of transforming growth factor-β-activated protein kinase 1(TAK1) in the development of diabetic nephropathy (DN) by regulating the protein stability of Ski-related novel protein N(SnoN).

MAIN METHODS

A combination of in vivo and in vitro model systems was used to investigate how TAK1 regulated the expression of SnoN protein in DN. The study determined the effects of modulating the expression or activity of TAK1 on the SnoN protein level and its influence on the epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) deposition.

KEY FINDINGS

Under the high-glucose condition, the activation of TGF-β1/TAK1-induced phosphorylation and ubiquitination of SnoN protein resulted in reduced SnoN protein level as a consequence of enhanced SnoN degradation, which promoted EMT and ECM deposition in renal tubular epithelial cells. The study showed that TAK1 impaired SnoN protein level by decreasing the protein stability of SnoN.

SIGNIFICANCE

TAK1 mediated the phosphorylation of SnoN, resulting in SnoN ubiquitination and eventual degradation, which enhanced EMT and ECM deposition to promote renal fibrosis during DN.

Role of cytokines and inflammation in heart function during health and disease

By virtue of their actions on NF-κB, an inflammatory nuclear transcription factor, various cytokines have been documented to play important regulatory roles in determining cardiac function under both physiological and pathophysiological conditions. Several cytokines including TNF-α, TGF-β, and different interleukins such as IL-1 IL-4, IL-6, IL-8, and IL-18 are involved in the development of various inflammatory cardiac pathologies, namely ischemic heart disease, myocardial infarction, heart failure, and cardiomyopathies. In ischemia-related pathologies, most of the cytokines are released into the circulation and serve as biological markers of inflammation. Furthermore, there is an evidence of their direct role in the pathogenesis of ischemic injury, suggesting cytokines as potential targets for the development of some anti-ischemic therapies. On the other hand, certain cytokines such as IL-2, IL-4, IL-6, IL-8, and IL-10 are involved in the post-ischemic tissue repair and thus are considered to exert beneficial effects on cardiac function. Conflicting reports regarding the role of some cytokines in inducing cardiac dysfunction in heart failure and different types of cardiomyopathies seem to be due to differences in the nature, duration, and degree of heart disease as well as the concentrations of some cytokines in the circulation. In spite of extensive research work in this field of investigation, no satisfactory anti-cytokine therapy for improving cardiac function in any type of heart disease is available in the literature.

Tetrahydroxy stilbene glucoside alleviates palmitic acid-induced inflammation and apoptosis in cardiomyocytes by regulating miR-129-3p/Smad3 signaling

Objective

Tetrahydroxy stilbene glucoside (TSG) has been reported to exert a cytoprotective effect against various toxicants. However, the function and mechanism of TSG in palmitic acid (PA)-induced inflammation and apoptosis in cardiomyocytes are still unknown. The present study was designed to investigate the post-transcriptional mechanism in TSG-treated cardiomyocytes’ inflammation and apoptosis induced by PA.

Methods

The mRNA and protein levels were assayed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting, respectively. The targeted genes were predicted by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay. Cell proliferation was analyzed by CCK-8 assay. Annexin V-fluorescein isothiocyanate/polyimide (annexin V-FITC/PI) staining was used to evaluate apoptosis using flow cytometry.

Results

TSG restricted the detrimental effects, including the activated inflammatory response and apoptosis, of PA in cardiomyocytes, as well as the up-regulation of miR-129-3p and down-regulation of p-Smad3 expression. In addition, bioinformatics and experimental analysis suggested that Smad3 was a direct target of miR-129-3p, which could inhibit or enhance the expression of p-Smad by transfection with miR-129-3p mimics or inhibitors, respectively. Furthermore, our results demonstrated that overexpression of Smad3 reversed the inhibition of inflammation and apoptosis by overexpression of miR-129-3p in PA-stimulated cardiomyocytes.

Conclusion

TSG targeted to miR-129-3p/Smad3 signaling inhibited PA-induced inflammation and apoptosis in cardiomyocytes.

Cardiac fibrosis: Cell biological mechanisms, molecular pathways and therapeutic opportunities

Cardiac fibrosis is a common pathophysiologic companion of most myocardial diseases, and is associated with systolic and diastolic dysfunction, arrhythmogenesis, and adverse outcome. Because the adult mammalian heart has negligible regenerative capacity, death of a large number of cardiomyocytes results in reparative fibrosis, a process that is critical for preservation of the structural integrity of the infarcted ventricle. On the other hand, pathophysiologic stimuli, such as pressure overload, volume overload, metabolic dysfunction, and aging may cause interstitial and perivascular fibrosis in the absence of infarction. Activated myofibroblasts are the main effector cells in cardiac fibrosis; their expansion following myocardial injury is primarily driven through activation of resident interstitial cell populations. Several other cell types, including cardiomyocytes, endothelial cells, pericytes, macrophages, lymphocytes and mast cells may contribute to the fibrotic process, by producing proteases that participate in matrix metabolism, by secreting fibrogenic mediators and matricellular proteins, or by exerting contact-dependent actions on fibroblast phenotype. The mechanisms of induction of fibrogenic signals are dependent on the type of primary myocardial injury. Activation of neurohumoral pathways stimulates fibroblasts both directly, and through effects on immune cell populations. Cytokines and growth factors, such as Tumor Necrosis Factor-α, Interleukin (IL)-1, IL-10, chemokines, members of the Transforming Growth Factor-β family, IL-11, and Platelet-Derived Growth Factors are secreted in the cardiac interstitium and play distinct roles in activating specific aspects of the fibrotic response. Secreted fibrogenic mediators and matricellular proteins bind to cell surface receptors in fibroblasts, such as cytokine receptors, integrins, syndecans and CD44, and transduce intracellular signaling cascades that regulate genes involved in synthesis, processing and metabolism of the extracellular matrix. Endogenous pathways involved in negative regulation of fibrosis are critical for cardiac repair and may protect the myocardium from excessive fibrogenic responses. Due to the reparative nature of many forms of cardiac fibrosis, targeting fibrotic remodeling following myocardial injury poses major challenges. Development of effective therapies will require careful dissection of the cell biological mechanisms, study of the functional consequences of fibrotic changes on the myocardium, and identification of heart failure patient subsets with overactive fibrotic responses.

Herbal compound 861 prevents hepatic fibrosis by inhibiting the TGF-β1/Smad/SnoN pathway in bile duct-ligated rats

BACKGROUND

This study was to evaluate the effects of herbal compound 861 (Cpd861) on ski-related novel protein N (SnoN) and transforming growth factor-β1 (TGF-β1) /Smad signaling in rats with bile duct ligation (BDL)-induced hepatic fibrosis, and to explore the mechanisms of Cpd861 on hepatic fibrosis.

METHODS

Thirty Wistar male rats were randomly divided into three groups: sham operation, BDL, and Cpd861. To induce hepatic fibrosis, BDL and Cpd861 group rats underwent bile duct ligation. Cpd861 at 9 g/kg/d or an equal volume of normal saline was administered intragastrically for 28 days. Liver injury was assessed biochemically and histologically. Protein and mRNA changes for SnoN and TGF-β1/Smad signaling (TGF-β1, Smad2, phosphorylated Smad2 [p-Smad2], phosphorylated Smad3 [p-Smad3], fibronectin, and collagen III) were determined by Western blotting and quantitative real-time PCR.

RESULTS

BDL rats treated with Cpd861 had significantly alleviated hepatic fibrosis compared to BDL rats not receiving Cpd861 treatment. Moreover, Cpd861 decreased the expression of fibrosis-associated proteins fibronectin and collagen III in liver tissue. Cpd861 administration increased the expression of SnoN protein, did not change SnoN mRNA level, and decreased TGF-β1, p-Smad2, and p-Smad3 protein expression compared to BDL without Cpd861 treatment.

CONCLUSIONS

Cpd861 attenuates hepatic fibrosis by increasing SnoN protein expression and inhibiting the TGF-β1/Smad signaling pathway.

Matrine suppresses cardiac fibrosis by inhibiting the TGF‑β/Smad pathway in experimental diabetic cardiomyopathy

Cardiac fibrosis is one of the pathological characteristics of diabetic cardiomyopathy (DbCM). Matrine treatment has proven to be effective in cases of organ fibrosis and cardiovascular diseases. In the present study, the anti-fibrosis-associated cardioprotective effects of matrine on DbCM were investigated. Rats with experimental DbCM were administered matrine orally. Cardiac functions were evaluated using invasive hemodynamic examinations. Cardiac compliance was assessed in isolated hearts. Using Sirius Red and fluorescence staining, the collagen in diabetic hearts was visualized. MTT assay was used to select non-cytotoxic concentrations of matrine, which were subsequently used to treat isolated cardiac fibroblasts incubated under various conditions. Western blotting was performed to assess activation of the transforming growth factor-β1 (TGF-β1)/Smad signaling pathway. Rats with DbCM exhibited impaired heart compliance and left ventricular (LV) functions. Excessive collagen deposition in cardiac tissue was also observed. Furthermore, TGF-β1/R-Smad (Smad2/3) signaling was revealed to be markedly activated; however, the expression of inhibitory Smad (I-Smad, also termed Smad7) was reduced in DbCM. Matrine administration led to a marked recovery in LV function and heart compliance by exerting inhibitory effects on TGF-β1/R-Smad signaling pathway-induced fibrosis without affecting I-Smad. Incubation with a high concentration of glucose triggered the TGF-β1/R-Smad (Smad2/3) signaling pathway and suppressed I-Smad signaling transduction in cultured cardiac fibroblasts, which led to an increase in the synthesis of collagen. After cardiac fibroblasts had been treated with matrine at non-cytotoxic concentrations without affecting I-Smad, matrine blocked TGF-β1/R-Smad signaling transduction to repress collagen production and deposition. In conclusion, the results of the present study demonstrated that TGF-β1/Smad signaling-associated cardiac fibrosis is involved in the impairment of heart compliance and LV dysfunction in DbCM. By exerting therapeutic effects against cardiac fibrosis via its influence on TGF-β1/Smad signaling, matrine exhibited cardioprotective effects in DbCM.

Down-regulation of miR-23a inhibits high glucose-induced EMT and renal fibrogenesis by up-regulation of SnoN

It has been reported that transforming growth factor-β1 (TGF-β1) signaling plays an important role in the development of diabetic nephropathy (DN). The nuclear transcription co-repressor Ski-related novel protein N (SnoN) is a critical negative regulator of TGF-β1/Smad signal pathway, involving in tubule epithelial-mesenchymal transition (EMT), extracellular matrix (ECM) accumulation, and tubulointerstitial fibrosis. In this study, we focused on miR-23a as a regulator of SnoN. Our purpose is to study the effects of miR-23a on high glucose (HG)-induced EMT process and ECM deposition in HK2 cells. We found that miR-23a was up-regulated in renal tissues of diabetic patients and HG-induced HK2 cells. Besides, the high level of miR-23a was closely associated with decreased SnoN expression. Knockdown of miR-23a increased SnoN expression and in turn suppressed HG-induced EMT and renal fibrogenesis. Introduction of miR-23a decreased SnoN expression and enhanced the profibrogenic effects of HG on HK2 cells. Next, bioinformatics analysis predicted that the SnoN was a potential target gene of miR-23a. Luciferase reporter assay demonstrated that miR-23a could directly target SnoN. We demonstrated that overexpression of SnoN was sufficient to inhibit HG-induced EMT and renal fibrogenesis in HK2 cells. Furthermore, down-regulation of SnoN partially reversed the protective effect of miR-23a knockdown on HG-induced EMT and renal fibrogenesis in HK2 cells. Collectively, miR-23a and SnoN significantly impact on the progression of HG-induced EMT and renal fibrogenesis in vitro, and they may represent novel targets for the prevention strategies of renal fibrosis in the context of DN.

SnoN suppresses TGF-β-induced epithelial-mesenchymal transition and invasion of bladder cancer in a TIF1γ-dependent manner

The transcriptional regulator SnoN (also known as SKI-like proto-oncogene, SKIL), a member of the Ski family, has been reported to influence epithelial-mesenchymal transition (EMT) in response to TGF-β. In the present study, we investigated the role of SnoN in bladder cancer (BC). Differential expression of SnoN was not detected in BC tissues compared with that noted in adjacent non-cancerous tissues. SnoN was upregulated in response to TGF-β treatment, but had no effect on the TGF-β pathway, which may be explained by the low level of SnoN SUMOylation. TIF1γ, which catalyzes the SUMOylation of SnoN, was downregulated in BC tissues. Overexpression of TIF1γ restored the ability of SnoN to suppress the TGF-β pathway. Furthermore, TGF-β-induced EMT and invasion of BC cells were suppressed by TIF1γ in the presence of SnoN. Collectirely, our data suggest that SnoN suppresses TGF-β‑induced EMT and invasion of BC cells in a TIF1γ‑dependent manner and may serve as a novel therapeutic option for the treatment of BC.

TGF-β receptor 1 inhibition prevents stenosis of tissue-engineered vascular grafts by reducing host mononuclear phagocyte activation

Stenosis is a critical problem in the long-term efficacy of tissue-engineered vascular grafts (TEVGs). We previously showed that host monocyte infiltration and activation within the graft drives stenosis and that TGF-β receptor 1 (TGF-βR1) inhibition can prevent it, but the latter effect was attributed primarily to inhibition of mesenchymal cell expansion. In this study, we assessed the effects of TGF-βR1 inhibition on the host monocytes. Biodegradable TEVGs were implanted as inferior vena cava interposition conduits in 2 groups of C57BL/6 mice (n = 25/group): unseeded grafts and unseeded grafts with TGF-βR1 inhibitor systemic treatment for the first 2 wk. The TGF-βR1 inhibitor treatment effectively improved TEVG patency at 6 mo compared to the untreated control group (91.7 vs. 48%, P < 0.001), which is associated with a reduction in classic activation of mononuclear phagocytes. Consistent with these findings, the addition of rTGF-β to LPS/IFN-γ-stimulated monocytes enhanced secretion of inflammatory cytokines TNF-α, IL-12, and IL-6; this effect was blocked by TGF-βR1 inhibition (P < 0.0001). These findings suggest that the TGF-β signaling pathway contributes to TEVG stenosis by inducing classic activation of host monocytes. Furthermore, blocking monocyte activation by TGF-βR1 inhibition provides a viable strategy for preventing TEVG stenosis while maintaining neotissue formation.-Lee, Y.-U., de Dios Ruiz-Rosado, J., Mahler, N., Best, C. A., Tara, S., Yi, T., Shoji, T., Sugiura, T., Lee, A. Y., Robledo-Avila, F., Hibino, N., Pober, J. S., Shinoka, T., Partida-Sanchez, S., Breuer, C. K. TGF-β receptor 1 inhibition prevents stenosis of tissue-engineered vascular grafts by reducing host mononuclear phagocyte activation.

TGFβ1 regulates Scleraxis expression in primary cardiac myofibroblasts by a Smad-independent mechanism

In cardiac wound healing following myocardial infarction (MI), relatively inactive resident cardiac fibroblasts phenoconvert to hypersynthetic/secretory myofibroblasts that produce large quantities of extracellular matrix (ECM) and fibrillar collagen proteins. Our laboratory and others have identified TGFβ1 as being a persistent stimulus in the chronic and inappropriate wound healing phase that is marked by hypertrophic scarring and eventual stiffening of the entire myocardium, ultimately leading to the pathogenesis of heart failure following MI. Ski is a potent negative regulator of TGFβ/Smad signaling with known antifibrotic effects. Conversely, Scleraxis is a potent profibrotic basic helix-loop-helix transcription factor that stimulates fibrillar collagen expression. We hypothesize that TGFβ1 induces Scleraxis expression by a novel Smad-independent pathway. Our data support the hypothesis that Scleraxis expression is induced by TGFβ1 through a Smad-independent pathway in the cardiac myofibroblast. Specifically, we demonstrate that TGFβ1 stimulates p42/44 (Erk1/2) kinases, which leads to increased Scleraxis expression. Inhibition of MEK1/2 using U0126 led to a sequential temporal reduction of phospho-p42/44 and subsequent Scleraxis expression. We also found that adenoviral Ski expression in primary myofibroblasts caused a significant repression of endogenous Scleraxis expression at both the mRNA and protein levels. Thus we have identified a novel TGFβ1-driven, Smad-independent, signaling cascade that may play an important role in regulating the fibrotic response in activated cardiac myofibroblasts following cardiac injury.

Activation of SIRT3 by resveratrol ameliorates cardiac fibrosis and improves cardiac function via the TGF-β/Smad3 pathway

Sirtuins [sirtuin (SIRT)1-SIRT7] mediate the longevity-promoting effects of calorie restriction in yeast, worms, flies, and mice. Additionally, SIRT3 is the only SIRT analog whose increased expression has been shown to be associated with longevity in humans. The polyphenol resveratrol (RSV) is the first compound discovered able to mimic calorie restriction by stimulating SIRTs. In the present study, we report that RSV activated SIRT3 in cardiac fibroblasts both in vivo and in vitro. Moreover, in wild-type mice, RSV prevented cardiac hypertrophy in response to hypertrophic stimuli. However, this protective effect was not observed in SIRT3 knockout mice. Additionally, the activation of SIRT3 by RSV ameliorated collagen deposition and improved cardiac function. In isolated cardiac fibroblasts, pretreatment with RSV suppressed fibroblast-to-myoblast transformation by inhibiting the transforming growth factor-β/Smad3 pathway. Therefore, these data indicate that the activation of SIRT3 by RSV could ameliorate cardiac fibrosis and improve cardiac function via the transforming growth factor-β/Smad3 pathway.