Notch signaling regulates col1α1 and col1α2 expression in airway fibroblasts

Role of Hippo pathway dysregulation from gastrointestinal premalignant lesions to cancer

BACKGROUND

First identified in Drosophila melanogaster, the Hippo pathway is considered a major regulatory cascade controlling tissue homeostasis and organ development. Hippo signaling components include kinases whose activity regulates YAP and TAZ final effectors. In response to upstream stimuli, YAP and TAZ control transcriptional programs involved in cell proliferation, cytoskeletal reorganization and stemness.

MAIN TEXT

While fine tuning of Hippo cascade components is essential for maintaining the balance between proliferative and non-proliferative signals, pathway signaling is frequently dysregulated in gastrointestinal cancers. Also, YAP/TAZ aberrant activation has been described in conditions characterized by chronic inflammation that precede cancer development, suggesting a role of Hippo effectors in triggering carcinogenesis. In this review, we summarize the architecture of the Hippo pathway and discuss the involvement of signaling cascade unbalances in premalignant lesions of the gastrointestinal tract, providing a focus on the underlying molecular mechanisms.

CONCLUSIONS

The biology of premalignant Hippo signaling dysregulation needs further investigation in order to elucidate the evolutionary trajectories triggering cancer inititation and develop effective early therapeutic strategies targeting the Hippo/YAP pathway.

Single-Cell Transcriptomic Profiling Identifies Molecular Phenotypes of Newborn Human Lung Cells

While animal model studies have extensively defined the mechanisms controlling cell diversity in the developing mammalian lung, there exists a significant knowledge gap with regards to late-stage human lung development. The NHLBI Molecular Atlas of Lung Development Program (LungMAP) seeks to fill this gap by creating a structural, cellular and molecular atlas of the human and mouse lung. Transcriptomic profiling at the single-cell level created a cellular atlas of newborn human lungs. Frozen single-cell isolates obtained from two newborn human lungs from the LungMAP Human Tissue Core Biorepository, were captured, and library preparation was completed on the Chromium 10X system. Data was analyzed in Seurat, and cellular annotation was performed using the ToppGene functional analysis tool. Transcriptional interrogation of 5500 newborn human lung cells identified distinct clusters representing multiple populations of epithelial, endothelial, fibroblasts, pericytes, smooth muscle, immune cells and their gene signatures. Computational integration of data from newborn human cells and with 32,000 cells from postnatal days 1 through 10 mouse lungs generated by the LungMAP Cincinnati Research Center facilitated the identification of distinct cellular lineages among all the major cell types. Integration of the newborn human and mouse cellular transcriptomes also demonstrated cell type-specific differences in maturation states of newborn human lung cells. Specifically, newborn human lung matrix fibroblasts could be separated into those representative of younger cells (n = 393), or older cells (n = 158). Cells with each molecular profile were spatially resolved within newborn human lung tissue. This is the first comprehensive molecular map of the cellular landscape of neonatal human lung, including biomarkers for cells at distinct states of maturity.

PCSK9 Inhibition Regulates Infarction-Induced Cardiac Myofibroblast Transdifferentiation via Notch1 Signaling

Increasing evidence suggests that PCSK9 inhibition protects cardiomyocytes against ischemia-reperfusion injury after myocardial infarction. However, it is not clear whether PCSK9 inhibitor (PCSK9i) affects cardiac fibroblasts (CFs) activation after MI. In this study we used SBC-115076, an antagonist of PCSK9, to investigate the role of PCSK9i in the conversion of CFs to cardiac myofibroblasts (CMFs) after MI and provided a basic for its clinical application in cardiac fibrosis after MI. In vivo study, PCSK9i was injected into mice 4 days after MI. Cardiac function and degree of fibrosis were evaluated by echocardiographic and tissue staining after treatment. Western blot showed that PCSK9i treatment decreases expression of α-SMA, collagen and increases expression of Notch1 in border infarct area. Vitro studies showed that PCSK9i decreased the degree of fibrosis, migration, and collagen fiber deposition in CFs. Confocal microscopy imaging also showed that hypoxia contributes to the formation of α-SMA stress filaments, and PCSK9i alleviated this state. Moreover, overexpression of Notch1 further suppress the activation of CFs under hypoxia. These results revealed that SBC-115076 ameliorates cardiac fibrosis and ventricular dysfunction post-myocardial infarction through inhibition of the differentiation of cardiac fibroblasts to myofibroblasts via Notch1/Hes1 signaling.

Bacterial cellulose membrane combined with BMSCs promotes wound healing by activating the notch signaling pathway

Objective

The bacterial cellulose membrane (BCM) has been widely studied and applied as a new biomaterial for wound healing, but causes pain with frequent dressing changes. Local application of bone marrow mesenchymal stem cells (BMSCs) requires a niche. Furthermore, the effect and mechanism of the BCM combined with BMSCs have not been reported.

Methods

Morphological and chemical identifications of BCMs were investigated by porosity analyses, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Biological wound dressings (BWDs) were prepared by the BCM in combination with BMSCs. The biological effects of BWDs on human dermal fibroblast (HDF) and VEGF-A in human vascular endothelial cells (HuVECs) were detected in vitro, and the effect of BWDs on acute wounds in mice was detected in vivo. Collagen and angiogenesis were evaluated through hematoxylin-eosin staining and Masson staining. The expressions of COL-1 and VEGF-A and the activation of the Notch signaling pathway in vivo and in vitro were detected by quantitative reverse-transcriptase polymerase chain reaction.

Results

The BCM had a nanoscale structure and provided a partial niche for the survival and proliferation of BMSCs. BWDs were successfully prepared and regulated the biological behaviors of wound healing-related cells in vitro and upregulated the expressions of COL-1 in HDF and VEGF-A in HuVECs. BWDs promoted wound healing by increasing collagen type I synthesis and angiogenesis in acute wounds in mice.

Conclusions

BWDs prepared by the combination of nanomaterial BCMs and BMSCs facilitated acute wound healing, which may be regulated by activating the Notch signaling pathway.

Oxidative stress mediated by the TLR4/NOX2 signalling axis is involved in polystyrene microplastic-induced uterine fibrosis in mice

Microplastics (MPs), as a new environmental pollutant, have received widespread attention worldwide. Uterine fibrosis is one of the main factors of female reproductive disorders. However, it is unclear whether the female reproductive disorders caused by MPs are related to uterine fibrosis. Therefore, in this study, we constructed female mouse models exposed to polystyrene microplastics (PS-MPs). We found that PS-MP exposure resulted in endometrial thinning and severe collagen fibre deposition in female mice. Further mechanistic studies found that PS-MP exposure increased the expression of high mobility group Box 1 (HMGB1) and acetyl-HMGB1, further activating the Toll-like receptor 4/NADPH oxidase 2 (TLR4/NOX2) signalling axis and eventually causing oxidative stress. Afterwards, oxidative stress elicited the activation of Notch and the transforming growth factor β (TGF-β) signalling pathway, leading to increased levels of fibrotic proteins and collagen. Correspondingly, PS-MP treatment upregulated the expression of TLR4 and NOX2 and the level of reactive oxygen species (ROS) and increased the levels of fibrotic protein and collagen in mouse endometrial epithelial cells cultured in vitro. Conversely, inhibition of the TLR4/NOX2 signalling pathway effectively reduced the level of ROS in cells, weakened the upregulation of Notch and TGF-β signalling by PS-MPs, and efficiently reduced the expression of fibrotic and collagen genes. In summary, we demonstrated a new mechanism by which MPs induce uterine fibrosis in mice, that is, by inducing oxidative stress to activate the Notch and TGF-β signalling pathways by triggering the TLR4/NOX2 signalling axis. Targeting TLR4/NOX2 signalling may consequently prove to be an innovative therapeutic option that is effective in alleviating the reproductive toxicity of PS-MPs. Our study sheds new light on the reproductive toxicity of MPs and provides suggestions and references for comparative medicine and clinical medicine.

Role of notch signaling pathway in Muc5ac secretion induced by atmospheric PM2.5 in rats

BACKGROUND

The secretion of Muc5ac is closely related to the pathogenesis, treatment and prognosis of bronchial asthma. Atmospheric PM_2.5 entered the airway can irritate and corrode the bronchial wall, affecting the expression and secretion of Muc5ac. However, the underlying mechanism is not clear. In this study, we investigated the role of the Notch signaling pathway in mucin section induced by atmospheric PM_2.5 in rats.

METHODS

Fifty rats were divided randomly into five groups: the control received physiological saline; the health, health Notch signaling pathway inhibition and asthma, asthma Notch signaling pathway inhibition groups received 7.5 mg/kg PM_2.5. PM_2.5 or saline was instilled into the trachea at 2-day intervals for two doses. IL-1β, TNF-α and Muc5ac levels were detected by ELISA. The mRNA expression levels of Notch signaling pathway genes were detected by real time PCR. The levels of Notch signaling pathway protein were detected by western blot.

RESULTS

The levels of Muc5ac in the lungs and TNF-α in serum of asthmatic rats exposed to PM2.5 was the highest, and when Notch signaling pathway was inhibited, the levels of Muc5ac in the lungs and tracheas and TNF-α in serum of asthmatic rats exposed to PM2.5 was significantly decreased. Hes1 mRNA expression level in trachea was the lowest in the asthma inhibition group; and inhibiting the Notch signaling pathway could decrease the mRNA and protein levels of Hes1 in rats' lung. The mRNA relative levels of Notch3 and Notch4 in rats' trachea, the protein levels of Notch3 in rats' lung, and the mRNA relative levels of Jagged1 and Jaggeed2 in rats' lung were more consist with the changes of Muc5ac, TNF-α and Hes1.

CONCLUSION

Notch signaling pathway played an important role in Muc5ac secretion induced by atmospheric PM_2.5 of the asthmatic rats' airways. Jagged1 and Jagged2 interacting with Notch3 and Notch4 regulated the expression of Hes1, further regulated TNF-α in the process of PM_2.5 inducing the secretion of Muc5ac.

The role of the Notch pathway in the pathogenesis of systemic sclerosis: clinical implications

INTRODUCTION

Systemic sclerosis (SSc) is a chronic debilitating disease characterized by vascular insufficiency, widespread fibrosis and immune activation. Current understanding of its pathophysiology remains incomplete, which translates into inefficient therapies. Notch signaling is a central player in the development of physiological and pathological fibrosis not only in general but also in the context of SSc and is most likely involved in the vascular dysfunction that characterizes the disease.

AREAS COVERED

This review explores the role of the Notch pathway in the pathophysiology of SSc and the potential implications for the diagnosis, evaluation, and management of this yet incurable disease.

EXPERT OPINION

Although major issues still exist about the comprehension of SSc and the design of effective treatments, the knowledge of the role of the Notch pathway in fibrogenesis and vascular biology has shed light and enthusiasm over the field. Drugs that target components of Notch signaling are currently in development including already some in clinical trials. As such, Notch may become a very important topic in the near future (considering both the pathophysiology and treatment perspectives), not only in the context of SSc but also in the vascular-dependent fibrotic processes present in a multitude of diseases.

Effects of a gamma-secretase inhibitor of notch signalling on transforming growth factor β1-induced urethral fibrosis

Urethral stricture (US) is a common disorder of the lower urinary tract in men caused by fibrosis. The recurrence rate of US is high; however, there are no effective therapies to prevent or treat urethral fibrosis. The pathogenesis of urethral fibrosis involves myofibroblast activation and excessive extracellular matrix (ECM) deposition. The molecular mechanisms underlying this pathological activation are not completely understood. It has been demonstrated that Notch signalling contributes to the development of fibrosis and inflammation. However, whether this contributes to urethral fibrosis remains unclear. In this study, activation of Notch signalling was observed in patients with US. Additionally, it was noted that activation of Notch signalling promoted ECM production and myofibroblast activation in human urethral scar fibroblasts (HUSFs) treated with transforming growth factor (TGF) β1. However, the Notch inhibitor N‐[N‐(3,5‐difluorophenacetyl)‐L‐alanyl]‐S‐phenylglycine t‐butyl ester (DAPT) suppressed activation of Notch signalling as well as proliferation and migration of the TGFβ1‐treated HUSFs. Additionally, DAPT ameliorated TGFβ1‐induced urethral fibrosis in Sprague Dawley rats by suppressing ECM production, myofibroblast activation and the TGFβ signalling pathway. These findings demonstrate that Notch signalling may be a promising and potential target in the prevention or treatment of urethral fibrosis.

Inhibition of Notch Intracellular Domain Suppresses Cell Activation and Fibrotic Factors Production in Hypertrophic Scar Fibroblasts Versus Normal Skin Fibroblasts

BACKGROUND

Hypertrophic scar (HS) is the most common complication after skin injury with unknown etiopathogenesis. There is increasing evidence to suggest that aberrant Notch signaling contributes directly to skin pathogenesis and altered expression of the Notch intracellular domain (NICD) identified in HS. Therefore, the aim of this study was to investigate the effects of Notch signaling pathway in HS pathogenesis.

METHODS

Hypertrophic scar and normal skin samples were collected. Notch intracellular domain expression was detected by immunohistochemistry staining and fibroblasts were separated from the samples. We compared fibrotic factors production, cell viability, migration and apoptosis of HS fibroblasts (HFB) versus normal skin fibroblasts (NFB) by real time quantitative polymerase chain reaction, MTS, cell scratch assay and flow cytometry respectively under the impact of inhibition of Notch signaling by NICD-small-interfering RNA (SiRNA).

RESULTS

The results showed that NICD was overexpressed in the dermis of HS tissues. Inhibition of Notch signaling by NICD-SiRNA suppressed the production of the fibrotic factors including collagen 1, collagen 3, α-SMA, and TGF-β1 by HFB and NFB. Cell viability and migration were reduced in NICD-SiRNA-treated NFB and HFB, whereas cell apoptosis was enhanced by NICD-SiRNA.

CONCLUSIONS

Conclusively, the study demonstrates a potential role for Notch signaling in HS progression, and targeting this pathway may provide a novel strategy for treatment of HS.

The Role of RECK in Hepatobiliary Neoplasia Reveals Its Therapeutic Potential in NASH

Non-alcoholic fatty liver disease (NAFLD) is a multimorbidity disorder ranging from excess accumulation of fat in the liver (steatosis) to steatohepatitis (NASH) and end-stage cirrhosis, and the development of hepatocellular carcinoma (HCC) in a subset of patients. The defining features of NASH are inflammation and progressive fibrosis. Currently, no pharmaceutical therapies are available for NAFLD, NASH and HCC; therefore, developing novel treatment strategies is desperately needed. Reversion Inducing Cysteine Rich Protein with Kazal motifs (RECK) is a well-known modifier of the extracellular matrix in hepatic remodeling and transition to HCC. More recently, its role in regulating inflammatory and fibrogenic processes has emerged. Here, we summarize the most relevant findings that extend our current understanding of RECK as a regulator of inflammation and fibrosis, and its induction as a potential strategy to blunt the development and progression of NASH and HCC.

Class C1 decoy oligodeoxynucleotide inhibits profibrotic genes expression in rat hepatic stellate cells

The aim of the present study was to investigate whether class C1 decoy oligodeoxynucleotides (ODNs) can inhibit the expression of pro‑fibrotic genes associated with rat hepatic stellate cell (HSC) activation and hepatic fibrosis. Luciferase reporter assays were performed to test the promoter activities of transforming growth factor (TGF)‑β and its downstream target genes following transfection of decoy ODNs and plasmids into HSC‑T6 cells, and western blot assays were performed to measure the protein expression of those genes following decoy ODN transfection. Class C1 decoy ODNs were confirmed to inhibit the promoter activity of TGF‑β and its downstream target genes, such as type 1 collagen (COLI)α1, tissue inhibitor of metalloproteinases (TIMP)1 and α‑smooth muscle actin by Gaussia luciferase reporter assay, and to further downregulate the expression of TGF‑β, SMAD3, COLIα1 and TIMP1 by western blotting in activated HSC‑T6 cells. In conclusion, class C1 decoy ODNs inhibited pro‑fibrotic gene expression in rat HSCS by downregulating TGF‑β signaling.

Silencing TBX1 Exerts Suppressive Effects on Epithelial-Mesenchymal Transition and Inflammation of Chronic Rhinosinusitis Through Inhibition of the TGF-Smad2/3 Signaling Pathway in Mice

Background

Chronic rhinosinusitis (CRS) is a multifactorial inflammatory disease characterized by high prevalence and morbidity, and little is known about the mechanisms that underlie its pathogenesis.

Objective

This study focuses on the effect of T-box 1 (TBX1) on the epithelial–mesenchymal transition (EMT) and inflammation of CRS via the transforming growth factor (TGF)β-Smad2/3 signaling pathway.

Methods

CRS mice models were established by Merocel nasal packing material, followed by the streptococcus pneumoniae cultivation. The expression levels of TBX1 in the sinus mucosa tissues of mice were measured accordingly. The successfully modeled mice were subsequently injected with TBX1 mimic or TBX1 inhibitor and the TGFβ-Smad2/3 signaling pathway inhibitor (SB-431542) to elucidate the influence of TBX1 on EMT and inflammation in CRS, with the expression of the EMT-related factors (E-cadherin, Vimentin, alpha-smooth muscle actin [α-SMA]), Th1 cytokines (interleukin [IL]-2, interferon-γ), and Th2 cytokines (IL-4, IL-8, total immunoglobulin E) assayed.

Results

TBX1 expression exhibited upregulated levels in the sinus mucosa tissues of the mice. In addition, TBX1 downregulation was found to inhibit the expression of TGFβ as well as the extent of Smad2 and Smad3 phosphorylation. Silencing TBX1 was shown to elevate the expression of Th1 cytokines and E-cadherin, while diminishing expression of Th2 cytokines, Vimentin and α-SMA.

Conclusions

Taken together, the key findings of our study highlight the inhibitory role of TBX1 in the process of EMT and inflammation in CRS mice via the inhibition of the TGFβ-Smad2/3 signaling pathway, underlining the promise of TBX1 as a potential target for CRS therapy.

Hyaluronan synthase 2-mediated hyaluronan production mediates Notch1 activation and liver fibrosis

Hyaluronan (HA), a major extracellular matrix glycosaminoglycan, is a biomarker for cirrhosis. However, little is known about the regulatory and downstream mechanisms of HA overproduction in liver fibrosis. Hepatic HA and HA synthase 2 (HAS2) expression was elevated in both human and murine liver fibrosis. HA production and liver fibrosis were reduced in mice lacking HAS2 in hepatic stellate cells (HSCs), whereas mice overexpressing HAS2 had exacerbated liver fibrosis. HAS2 was transcriptionally up-regulated by transforming growth factor-β through Wilms tumor 1 to promote fibrogenic, proliferative, and invasive properties of HSCs via CD44, Toll-like receptor 4 (TLR4), and newly identified downstream effector Notch1. Inhibition of HA synthesis by 4-methylumbelliferone reduced HSC activation and liver fibrosis in mice. Our study provides evidence that HAS2 actively synthesizes HA in HSCs and that it promotes HSC activation and liver fibrosis through Notch1. Targeted HA inhibition may have potential to be an effective therapy for liver fibrosis.

Transcriptomics Analysis Reveals New Insights into the Roles of Notch1 Signaling on Macrophage Polarization

Naïve macrophages (Mφ) polarize in response to various environmental cues to a spectrum of cells that have distinct biological functions. The extreme ends of the spectrum are classified as M1 and M2 macrophages. Previously, we demonstrated that Notch1 deficiency promotes Tgf-β2 dependent M2-polarization in a mouse model of abdominal aortic aneurysm. The present studies aimed to characterize the unique set of genes regulated by Notch1 signaling in macrophage polarization. Bone marrow derived macrophages isolated from WT or Notch1+/- mice (n = 12) were differentiated to Mφ, M1 or M2-phenotypes by 24 h exposure to vehicle, LPS/IFN-γ or IL4/IL13 respectively and total RNA was subjected to RNA-Sequencing (n = 3). Bioinformatics analyses demonstrated that Notch1 haploinsufficiency downregulated the expression of 262 genes at baseline level, 307 genes with LPS/IFN-γ and 254 genes with IL4/IL13 treatment. Among these, the most unique genes downregulated by Notch1 haploinsufficiency included fibromodulin (Fmod), caspase-4, Has1, Col1a1, Alpl and Igf. Pathway analysis demonstrated that extracellular matrix, macrophage polarization and osteogenesis were the major pathways affected by Notch1 haploinsufficiency. Gain and loss-of-function studies established a strong correlation between Notch1 haploinsufficiency and Fmod in regulating Tgf-β signaling. Collectively, our studies suggest that Notch1 haploinsufficiency increases M2 polarization through these newly identified genes.

NOTCH3 Overexpression and Posttranscriptional Regulation by miR-150 Were Associated With EGFR-TKI Resistance in Lung Adenocarcinoma

Acquired resistance remains a key challenge in epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) therapy in lung adenocarcinoma (LUAD). Recent studies have shown that Notch signaling is associated with drug resistance. However, its role and possible mechanisms in EGFR-TKI resistance are not yet clear. In our study, we found that among four members of NOTCH1-4, only NOTCH3 was upregulated in LUAD tissues and TKI-resistant cell line (HCC827GR6). Knockdown of NOTCH3 by siRNA significantly inhibited proliferative ability, and decreased colony and sphere formation in HCC827GR6 cells. Then miR-150 was identified as a posttranscriptional regulator of NOTCH3. Its expression was downregulated in LUAD tissues and negatively correlated with NOTCH3 mRNA. The cell proliferation and IC₅₀ of gefitinib were decreased in HCC827GR6 cells transfected with miR-150 mimic, but was reversed when cotransfected with NOTCH3 overexpressed vector. Moreover, we also enrolled 20 patients with advanced LUAD who have taken TKIs as first-line therapy in this study. We found that collagen 1A1 (COL1A1) expression was increased significantly in LUAD tissues both at mRNA and protein levels, and positively correlated with NOTCH3 expression verified in our data and TCGA data. Univariate survival analysis showed that patients with high protein expression of NOTCH3 or COL1A1 were associated with shorter overall survival (OS). Taken together, these results suggest that miR-150/NOTCH3/COL1A1 axis contributed to EGFR-TKI resistance in LUAD, which provide a potential therapeutic target for LUAD treatment.

Cancer driver mutations in endometriosis: Variations on the major theme of fibrogenesis

BACKGROUND

One recent study reports cancer driver mutations in deep endometriosis, but its biological/clinical significance remains unclear. Since the natural history of endometriosis is essentially gradual progression toward fibrosis, it is thus hypothesized that the six driver genes reported to be mutated in endometriosis (the RP set) may play important roles in fibrogenesis but not necessarily malignant transformation.

METHODS

Extensive PubMed search to see whether RP and another set of driver genes not yet reported (NR) to be mutated in endometriosis have any roles in fibrogenesis. All studies reporting on the role of fibrogenesis of the genes in both RP and NR sets were retrieved and evaluated in this review.

RESULTS

All six RP genes were involved in various aspects of fibrogenesis as compared with only three NR genes. These nine genes can be anchored in networks linking with their upstream and downstream genes that are known to be aberrantly expressed in endometriosis, piecing together seemingly unrelated findings.

CONCLUSIONS

Given that somatic driver mutations can and do occur frequently in physiologically normal tissues, it is argued that these mutations in endometriosis are not necessarily synonymous with malignancy or premalignancy, but the result of enormous pressure for fibrogenesis.

Matrine blocks AGEs- induced HCSMCs phenotypic conversion via suppressing Dll4-Notch pathway

Vascular smooth muscle cells (VSMCs) contractile- synthetic phenotypic conversion takes responsibility in the atherosclerotic plaque formation by abnormal synthesis, secretion and deposition of extracellular matrix (ECM). Matrine exerts therapeutic effects on both cardiovascular diseases and organ fibrosis. In this study, we investigated matrine's inhibitory effect and mechanisms on AGEs- induced VSMC contractile- synthetic phenotypic conversion. Cultured human coronary smooth muscle cells (HCSMCs) were exposed to AGEs. Matrine at serially diluted concentrations were used to treat the cells. HCSMCs phenotype was identified by immunofluorescent staining of contractile phenotypic markers including mooth muscle myosin heavy chain (MYH11) and smooth muscle α-actin (ACTA2). Sircol collagen assay was used to assess the collagen secretion level. Notch signaling activation was determined by luciferase assay. Western blotting was used to evaluate expression levels of collagen I, collagen VIII, Delta-like (Dll)1, Dll3, Dll4, Jagged1, Jagged2, Notch intracellular domain (NICD)1 and Hes family basic helix-loop-helix (bHLH) transcription factor1 (HES1). Matrine pre-treatment recovered the AGEs- induced contractile- synthetic phenotypic conversion by increasing MYH11 and ACTA2 in HCSMCs. Matrine reduced AGEs- mediated activation of Notch signaling, down-regulated expression levels of NICD1, HES1, collagen I and collagen VIII and collagen secretion contents in HCSMCs. Matrine inhibited expression level of Dll4 without affecting other Notch ligands including Dll1, Dll3, Jagged1 and Jagged2 in HCSMCs exposed to AGEs. These results suggested that AGEs exposure facilitated the contractile- synthetic phenotypic conversion of HCSMCs. Matrine blocked this phenotypic conversion by suppressing Dll4- Notch signaling pathway activation.

Myeloid-specific targeting of Notch ameliorates murine renal fibrosis via reduced infiltration and activation of bone marrow-derived macrophage

Macrophages play critical roles in renal fibrosis. However, macrophages exhibit ontogenic and functional heterogeneities, and which population of macrophages contributes to renal fibrosis and the underlying mechanisms remain unclear. In this study, we genetically targeted Notch signaling by disrupting the transcription factor recombination signal binding protein-Jκ (RBP-J), to reveal its role in regulation of macrophages during the unilateral ureteral obstruction (UUO)-induced murine renal fibrosis. Myeloid-specific disruption of RBP-J attenuated renal fibrosis with reduced extracellular matrix deposition and myofibroblast activation, as well as attenuated epithelial-mesenchymal transition, likely owing to the reduced expression of TGF-β. Meanwhile, RBP-J deletion significantly hampered macrophage infiltration and activation in fibrotic kidney, although their proliferation appeared unaltered. By using macrophage clearance experiment, we found that kidney resident macrophages made negligible contribution, but bone marrow (BM)-derived macrophages played a major role in renal fibrogenesis. Further mechanistic analyses showed that Notch blockade reduced monocyte emigration from BM by down-regulating CCR2 expression. Finally, we found that myeloid-specific Notch activation aggravated renal fibrosis, which was mediated by CCR2⁺ macrophages infiltration. In summary, our data have unveiled that myeloid-specific targeting of Notch could ameliorate renal fibrosis by regulating BM-derived macrophages recruitment and activation, providing a novel strategy for intervention of this disease.

Notch Signaling: Linking Embryonic Lung Development and Asthmatic Airway Remodeling

Lung development is mediated by assorted signaling proteins and orchestrated by complex mesenchymal-epithelial interactions. Notch signaling is an evolutionarily conserved cell-cell communication mechanism that exhibits a pivotal role in lung development. Notably, both aberrant expression and loss of regulation of Notch signaling are critically linked to the pathogenesis of various lung diseases, in particular, pulmonary fibrosis, lung cancer, pulmonary arterial hypertension, and asthmatic airway remodeling; implying that precise regulation of intensity and duration of Notch signaling is imperative for appropriate lung development. Moreover, evidence suggests that Notch signaling links embryonic lung development and asthmatic airway remodeling. Herein, we summarized all-recent advances associated with the mechanistic role of Notch signaling in lung development, consequences of aberrant expression or deletion of Notch signaling in linking early-impaired lung development and asthmatic airway remodeling, and all recently investigated potential therapeutic strategies to treat asthmatic airway remodeling.

HES1 promotes extracellular matrix protein expression and inhibits proliferation and migration in human trabecular meshwork cells under oxidative stress

Glaucoma is the leading cause of irreversible blindness. The most prevalent form of glaucoma is primary open-angle glaucoma (POAG). Oxidative stress is one of the major pathogenic factors of the POAG, and can elicit molecular and functional changes in trabecular meshwork cells, causing increased aqueous humor outflow resistance and elevated intraocular pressure. However, the regulatory mechanisms underlying oxidative stress-induced cell phenotypic changes remain elusive. Herein, we exposed primary human trabecular meshwork cells to the oxidative stress induced by 300 μM H₂O₂ for 2 h, and found significantly up-regulated expression of extracellular matrix proteins and a transcription factor, hairy and enhancer of split-1 (HES1). The cell functions, including migration and proliferation, were impaired by the oxidative stress. Furthermore, HES1 shRNA abrogated the extracellular matrix protein up-regulation and rescued the functional defects caused by the oxidative stress; conversely, HES1 overexpression resulted in the molecular and functional changes similar to those induced by H₂O₂. These results suggest that HES1 promotes extracellular matrix protein expression and inhibits proliferative and migratory functions in the trabecular meshwork cells under oxidative stress, thereby providing a novel pathogenic mechanism underlying and a potential therapeutic target to the POAG.

MDM2 mediates fibroblast activation and renal tubulointerstitial fibrosis via a p53-independent pathway

It is well recognized that murine double minute gene 2 (MDM2) plays a critical role in cell proliferation and inflammatory processes during tumorigenesis. It is also reported that MDM2 is expressed in glomeruli and involved in podocyte injury. However, whether MDM2 is implicated in renal fibrosis remains unclear. Here we investigated the role of MDM2 in tubulointerstitial fibrosis (TIF). By immunohistochemical staining and Western blotting we confirmed that MDM2 is upregulated in the tubulointerstitial compartment in patients with TIF and unilateral urethral obstruction (UUO) mice, which mainly originates from myofibroblasts. Consistently, in vitro MDM2 is increased in TGF-β1-treated fibroblasts, one of the major sources of collagen-producing myofibroblasts during TIF, along with fibroblast activation. Importantly, genetic deletion of MDM2 significantly attenuates fibroblast activation. We then analyzed the possible downstream signaling of MDM2 during fibroblast activation. p53-dependent pathway is the classic downstream signaling of MDM2, and Nutlin-3 is a small molecular inhibitor of MDM2-p53 interaction. To our surprise, Nutlin-3 could not ameliorate fibroblast activation in vitro and TIF in UUO mice. However, we found that Notch1 signaling is attenuated during fibroblast activation, which could be markedly rescued by MDM2 knockdown. Overexpression of intracellular domain of Notch1 (NICD) by plasmid could obviously minimize fibroblast activation induced by TGF-β1. In addition, the degradation of NICD is strikingly suppressed by PYR-41, an inhibitor of ubiquitin-activating enzyme E1, and proteasome inhibitor MG132. Taken together, our findings provide the first evidence that MDM2 is involved in fibroblast activation and TIF, which associates with Notch1 ubiquitination and proteasome degradation.

Notch: A multi-functional integrating system of microenvironmental signals

The Notch signaling cascade is an evolutionarily ancient system that allows cells to interact with their microenvironmental neighbors through direct cell-cell interactions, thereby directing a variety of developmental processes. Recent research is discovering that Notch signaling is also responsive to a broad variety of stimuli beyond cell-cell interactions, including: ECM composition, crosstalk with other signaling systems, shear stress, hypoxia, and hyperglycemia. Given this emerging understanding of Notch responsiveness to microenvironmental conditions, it appears that the classical view of Notch as a mechanism enabling cell-cell interactions, is only a part of a broader function to integrate microenvironmental cues. In this review, we summarize and discuss published data supporting the idea that the full function of Notch signaling is to serve as an integrator of microenvironmental signals thus allowing cells to sense and respond to a multitude of conditions around them.

ω-3 PUFAs ameliorate liver fibrosis and inhibit hepatic stellate cells proliferation and activation by promoting YAP/TAZ degradation

Elevated levels of the transcriptional regulators Yes-associated protein (YAP) and transcriptional coactivators with PDZ-binding motif (TAZ), key effectors of the Hippo pathway, have been shown to play essential roles in controlling liver cell fate and the activation of hepatic stellate cells (HSCs). The dietary intake of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) has been positively associated with a number of health benefits including prevention and reduction of cardiovascular diseases, inflammation and cancers. However, little is known about the impact of ω-3 PUFAs on liver fibrosis. In this study, we used CCl₄-induced liver fibrosis mouse model and found that YAP/TAZ is over-expressed in the fibrotic liver and activated HSCs. Fish oil administration to the model mouse attenuates CCl₄-induced liver fibrosis. Further study revealed that ω-3 PUFAs down-regulate the expression of pro-fibrogenic genes in activated HSCs and fibrotic liver, and the down-regulation is mediated via YAP, thus identifying YAP as a target of ω-3 PUFAs. Moreover, ω-3 PUFAs promote YAP/TAZ degradation in a proteasome-dependent manner. Our data have identified a mechanism of ω-3 PUFAs in ameliorating liver fibrosis.

Promoter Assay Using Luciferase Reporter Gene in the A549 Cell Line

The development of reporters systems has simplified the study of promoter activity in different areas of knowledge, and represents an easy and fast approach to study genetic variations. In this chapter, we show a transfection protocol of A549 lung epithelial cells with a reporter vector, using the Luciferase-Renilla dual system for studying the variations caused by several polymorphisms in the promoter region of a gene.

Notch in fibrosis and as a target of anti-fibrotic therapy

The Notch pathway represents a highly conserved signaling network with essential roles in regulation of key cellular processes and functions, many of which are critical for development. Accumulating evidence indicates that it is also essential for fibrosis and thus the pathogenesis of chronic fibroproliferative diseases in diverse organs and tissues. Different effects of Notch activation are observed depending on cellular and tissue context as well as in both physiologic and pathologic states. Close interactions of Notch signaling pathway with other signaling pathways have been identified. In this review, current knowledge on the role of the Notch signaling with special focus on fibrosis and its potential as a therapeutic target is summarized.

Mesenchymal deficiency of Notch1 attenuates bleomycin-induced pulmonary fibrosis

Notch signaling pathway is involved in the regulation of cell fate, differentiation, proliferation, and apoptosis in development and disease. Previous studies suggest the importance of Notch1 in myofibroblast differentiation in lung alveogenesis and fibrosis. However, direct in vivo evidence of Notch1-mediated myofibroblast differentiation is lacking. In this study, we examined the effects of conditional mesenchymal-specific deletion of Notch1 on pulmonary fibrosis. Crossing of mice bearing the floxed Notch1 gene with α2(I) collagen enhancer-Cre-ER(T)-bearing mice successfully generated progeny with a conditional knockout (CKO) of Notch1 in collagen I-expressing (mesenchymal) cells on treatment with tamoxifen (Notch1 CKO). Because Notch signaling is known to be activated in the bleomycin model of pulmonary fibrosis, control and Notch1 CKO mice were analyzed for their responses to bleomycin treatment. The results showed significant attenuation of pulmonary fibrosis in CKO relative to control mice, as examined by collagen deposition, myofibroblast differentiation, and histopathology. However, there were no significant differences in inflammatory or immune cell influx between bleomycin-treated CKO and control mouse lungs. Analysis of isolated lung fibroblasts confirmed absence of Notch1 expression in cells from CKO mice, which contained fewer myofibroblasts and significantly diminished collagen I expression relative to those from control mice. These findings revealed an essential role for Notch1-mediated myofibroblast differentiation in the pathogenesis of pulmonary fibrosis.