TGF-β1 signaling regulates mouse hepatic stellate cell differentiation via the Jagged1/Notch pathway

Insufficient GDF15 expression predisposes women to unexplained recurrent pregnancy loss by impairing extravillous trophoblast invasion

Insufficient extravillous trophoblast (EVT) invasion during early placentation has been shown to contribute to recurrent pregnancy loss (RPL). However, the regulatory factors involved and their involvement in RPL pathogenesis remain unknown. Here, we found aberrantly decreased growth differentiation factor 15 (GDF15) levels in both first-trimester villous and serum samples of unexplained recurrent pregnancy loss (URPL) patients as compared with normal pregnancies. Moreover, GDF15 knockdown significantly reduced the invasiveness of both HTR-8/SVneo cells and primary human EVT cells and suppressed the Jagged-1 (JAG1)/NOTCH3/HES1 pathway activity, and JAG1 overexpression rescued the invasion phenotype of the GDF15 knockdown cells. Induction of a lipopolysaccharide-induced abortion model in mice resulted in significantly reduced GDF15 level in the placenta and serum, as well as increased rates of embryonic resorption, and these effects were reversed by administration of recombinant GDF15. Our study thus demonstrates that insufficient GDF15 level at the first-trimester maternal-foetal interface contribute to the pathogenesis of URPL by impairing EVT invasion and suppressing JAG1/NOTCH3/HES1 pathway activity, and suggests that supplementation with GDF15 could benefit early pregnancy maintenance and reduce the risk of early pregnancy.

Characterization of human stem cell-derived hepatic stellate cells and liver sinusoidal endothelial cells during extended in vitro culture

Background: There is a significant need for predictive and stable in vitro human liver representations for disease modeling and drug testing. Hepatic stellate cells (HSCs) and liver sinusoidal endothelial cells (LSECs) are important non-parenchymal cell components of the liver and are hence of relevance in a variety of disease models, including hepatic fibrosis. Pluripotent stem cell- (PSC-) derived HSCs (scHSCs) and LSECs (scLSECs) offer an attractive alternative to primary human material; yet, the suitability of scHSCs and scLSECs for extended in vitro modeling has not been characterized. Methods: In this study, we describe the phenotypic and functional development of scHSCs and scLSECs during 14 days of 2D in vitro culture. Cell-specific phenotypes were evaluated by cell morphology, immunofluorescence, and gene- and protein expression. Functionality was assessed in scHSCs by their capacity for intracellular storage of vitamin A and response to pro-fibrotic stimuli induced by TGF-β. scLSECs were evaluated by nitric oxide- and factor VIII secretion as well as endocytic uptake of bioparticles and acetylated low-density lipoprotein. Notch pathway inhibition and co-culturing scHSCs and scLSECs were separately tested as options for enhancing long-term stability and maturation of the cells. Results and Conclusion: Both scHSCs and scLSECs exhibited a post-differentiation cell type-specific phenotype and functionality but deteriorated during extended culture with PSC line-dependent variability. Therefore, the choice of PSC line and experimental timeframe is crucial when designing in vitro platforms involving scHSCs and scLSECs. Notch inhibition modestly improved long-term monoculture in a cell line-dependent manner, while co-culturing scHSCs and scLSECs provides a strategy to enhance phenotypic and functional stability.

Cellular and Molecular Biology of Cancer Stem Cells of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death globally. The cancer stem cells (CSCs) of HCC are responsible for tumor growth, invasion, metastasis, recurrence, chemoresistance, target therapy resistance and radioresistance. The reported main surface markers used to identify liver CSCs include epithelial cell adhesion/activating molecule (EpCAM), cluster differentiation 90 (CD90), CD44 and CD133. The main molecular signaling pathways include the Wnt/β-catenin, transforming growth factors-β (TGF-β), sonic hedgehog (SHH), PI3K/Akt/mTOR and Notch. Patients with EpCAM-positive alpha-fetoprotein (AFP)-positive HCC are usually young but have advanced tumor-node-metastasis (TNM) stages. CD90-positive HCCs are usually poorly differentiated with worse prognosis. Those with CD44-positive HCC cells develop early metastases. Those with CD133 expression have a higher recurrence rate and a shorter overall survival. The Wnt/β-catenin signaling pathway triggers angiogenesis, tumor infiltration and metastasis through the enhancement of angiogenic factors. All CD133+ liver CSCs, CD133+/EpCAM+ liver CSCs and CD44+ liver CSCs contribute to sorafenib resistance. SHH signaling could protect HCC cells against ionizing radiation in an autocrine manner. Reducing the CSC population of HCC is crucial for the improvement of the therapy of advanced HCC. However, targeting CSCs of HCC is still challenging.

TKF, a mexicanolide-type limonoid derivative, suppressed hepatic stellate cells activation and liver fibrosis through inhibition of the YAP/Notch3 pathway

BACKGROUND

Liver fibrosis is a common scarring response and may ultimately lead to liver cancer, unfortunately, there is currently no effective antifibrotic drug approved for human use. Limonoids exhibit a broad spectrum of biological activities; however, the potential role of limonoids against fibrosis is largely unknown.

PURPOSE

This study investigates the antifibrotic activities and potential mechanisms of TKF (3-tigloyl-khasenegasin F), a natural mexicanolide-type limonoid derivative.

STUDY DESIGN/METHODS

Two well-established mouse models (CCl₄ challenge and bile duct ligation) were used to assess anti-fibrotic effects of TKF in vivo. Human hepatic stellate cell (HSC) line LX-2 and mouse primary hepatic stellate cells (pHSCs) also served as in vitro liver fibrosis models.

RESULT

TKF administration significantly attenuated hepatic histopathological injury and collagen accumulation and suppressed fibrogenesis-associated gene expression including Col1a1, Acta2, and Timp1. In LX-2 cells and mouse pHSCs, TKF dose-dependently suppressed HSC activation and the expression levels of fibrogenic markers. Mechanistic studies showed that TKF inhibited Notch3-Hes1 and YAP signalings in vivo and in vitro. Furthermore, YAP inhibition or knockdown downregulated the Notch3 expression; however, Notch3 inhibition or knockdown did not affect the level of YAP in activated HSC. We revealed that TKF inhibited Notch3-Hes1 activation and downregulated hepatic fibrogenic gene expression via inhibiting YAP.

CONCLUSION

The therapeutic benefit of TKF against liver fibrosis results from inhibition of YAP and Notch3-Hes1 pathways, indicating that TKF may be a novel therapeutic candidate for liver fibrosis.

Glycyrrhizin and its derivatives promote hepatic differentiation via sweet receptor, Wnt, and Notch signaling

The acute liver disease is involved in aberrant release of high-mobility group box 1 (HMGB1). Glycyrrhizin (GL), a traditional Chinese medicine for liver disease, binds to HMGB1, thereby inhibits tissue injury. However the mode of action of GL for chronic liver disease remains unclear. We investigated the effects of glycyrrhizin (GL) and its derivatives on liver differentiation using human iPS cells by using a flow cytometric analysis. GL promoted hepatic differentiation at the hepatoblast formation stage. The GL derivatives, 3-O-mono-glucuronyl 18β-glycyrrhetinic acid (Mono) and 3-O-[glucosyl (1 → 2)-glucuronyl] 18β-glycyrrhetinic acid increased AFP⁺ cell counts and albumin⁺ cell counts. Glucuronate conjugation seemed to be a requirement for hepatic differentiation. Mono exhibited the most significant hepatic differentiation effect. We evaluated the effects of (±)-2-(2,4-dichlorophenoxy) propionic acid (DP), a T1R3 antagonist, and sucralose, a T1R3 agonist, on hepatic differentiation, and found that DP suppressed Mono-induced hepatic differentiation, while sucralose promoted hepatic differentiation. Thus, GL promoted hepatic differentiation via T1R3 signaling. In addition, Mono increased β-catenin⁺ cell count and decreased Hes5⁺ cell count suggesting the involvement of Wnt and Notch signaling in GL-induced hepatic differentiation. In conclusion, GL exerted a hepatic differentiation effect via sweet receptor (T1R3), canonical Wnt, and Notch signaling.

The role of mesenchymal stem cells in liver injury

Recently, mesenchymal stem cell (MSC) therapy has been suggested as an effective alternate approach for the treatment of hepatic diseases. MSCs have potential therapeutic value, because these have high self-renewal ability, are capable of multipotent differentiation, and have low immunogenicity. Furthermore, MSCs have the potential to differentiate into hepatocytes, and the therapeutic value exists in their immune-modulatory properties and secretion of trophic factors, such as growth factors and cytokines. Moreover, MSCs can suppress inflammatory responses, reduce hepatocyte apoptosis, increase hepatocyte regeneration, regress liver fibrosis, and enhance liver functionality. This article is protected by copyright. All rights reserved.

A Synopsis of Signaling Crosstalk of Pericytes and Endothelial Cells in Salivary Gland

The salivary gland (SG) microvasculature constitutes a dynamic cellular organization instrumental to preserving tissue stability and homeostasis. The interplay between pericytes (PCs) and endothelial cells (ECs) culminates as a key ingredient that coordinates the development, maturation, and integrity of vessel building blocks. PCs, as a variety of mesenchymal stem cells, enthrall in the field of regenerative medicine, supporting the notion of regeneration and repair. PC-EC interconnections are pivotal in the kinetic and intricate process of angiogenesis during both embryological and post-natal development. The disruption of this complex interlinkage corresponds to SG pathogenesis, including inflammation, autoimmune disorders (Sjögren’s syndrome), and tumorigenesis. Here, we provided a global portrayal of major signaling pathways between PCs and ECs that cooperate to enhance vascular steadiness through the synergistic interchange. Additionally, we delineated how the crosstalk among molecular networks affiliate to contribute to a malignant context. Additionally, within SG microarchitecture, telocytes and myoepithelial cells assemble a labyrinthine companionship, which together with PCs appear to synchronize the regenerative potential of parenchymal constituents. By underscoring the intricacy of signaling cascades within cellular latticework, this review sketched a perceptive basis for target-selective drugs to safeguard SG function.

Hepatocyte TLR4 triggers inter-hepatocyte Jagged1/Notch signaling to determine NASH-induced fibrosis

Aberrant hepatocyte Notch activity is critical to the development of nonalcoholic steatohepatitis (NASH)-induced liver fibrosis, but mechanisms underlying Notch reactivation in developed liver are unclear. Here, we identified that increased expression of the Notch ligand Jagged1 (JAG1) tracked with Notch activation and nonalcoholic fatty liver disease (NAFLD) activity score (NAS) in human liver biopsy specimens and mouse NASH models. The increase in Jag1 was mediated by hepatocyte Toll-like receptor 4 (TLR4)-nuclear factor κB (NF-κB) signaling in pericentral hepatocytes. Hepatocyte-specific Jag1 overexpression exacerbated fibrosis in mice fed a high-fat diet or a NASH-provoking diet rich in palmitate, cholesterol, and sucrose and reversed the protection afforded by hepatocyte-specific TLR4 deletion, whereas hepatocyte-specific Jag1 knockout mice were protected from NASH-induced liver fibrosis. To test therapeutic potential of this biology, we designed a Jag1-directed antisense oligonucleotide (ASO) and a hepatocyte-specific N-acetylgalactosamine (GalNAc)-modified siRNA, both of which reduced NASH diet-induced liver fibrosis in mice. Overall, these data demonstrate that increased hepatocyte Jagged1 is the proximal hit for Notch-induced liver fibrosis in mice and suggest translational potential of Jagged1 inhibitors in patients with NASH.

Fibrotic Events in the Progression of Cholestatic Liver Disease

Cholestatic liver diseases including primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are associated with active hepatic fibrogenesis, which can ultimately lead to the development of cirrhosis. However, the exact relationship between the development of liver fibrosis and the progression of cholestatic liver disease remains elusive. Periductular fibroblasts located around the bile ducts seem biologically different from hepatic stellate cells (HSCs). The fibrotic events in these clinical conditions appear to be related to complex crosstalk between immune/inflammatory mechanisms, cytokine signalling, and perturbed homeostasis between cholangiocytes and mesenchymal cells. Several animal models including bile duct ligation (BDL) and the Mdr2-knockout mice have improved our understanding of mechanisms underlying chronic cholestasis. In the present review, we aim to elucidate the mechanisms of fibrosis in order to help to identify potential diagnostic and therapeutic targets.

Human amniotic fluid stem cells attenuate cholangiocyte apoptosis in a bile duct injury model of liver ductal organoids

PURPOSE

Biliary atresia (BA) is a fibro-obliterative cholangiopathy that involves both extrahepatic and intrahepatic bile ducts in infants. Cholangiocyte apoptosis has an influence on the fibrogenesis process of bile ducts and the progression of liver fibrosis in BA. Human amniotic fluid stem cells (hAFSCs) are multipotent cells that have ability to inhibit cell apoptosis. We aimed to investigate whether hAFSCs have the potential to attenuate cholangiocyte apoptosis and injury induced fibrogenic response in our ex vivo bile duct injury model of liver ductal organoids.

METHODS

The anti-apoptotic effect of hAFSCs was tested in the acetaminophen-induced injury model of neonatal mouse liver ductal organoids (AUP #42681) by using direct and indirect co-culture systems. Cell apoptosis and proliferation were evaluated by immunofluorescent staining. Expression of fibrogenic cytokines was analyzed by RT-qPCR. Data were compared using one-way ANOVA with post hoc test.

RESULTS

In our injury model, liver ductal organoids that were treated with hAFSCs in both direct and indirect co-culture systems had a significantly smaller number of apoptotic cholangiocytes and decreased expression of fibrogenic cytokines, transforming growth factor beta-1 (TGF-β1) and platelet-derived growth factor-BB (PDGF-BB). Moreover, hAFSCs increased cholangiocyte proliferation in injured organoids.

CONCLUSION

hAFSCs have the ability to protect the organoids from injury by decreasing cholangiocyte apoptosis and promoting cholangiocyte proliferation. This protective ability of hAFSCs leads to inhibition of the fibrogenic response in the injured organoids. hAFSCs have high therapeutic potential to attenuate liver fibrogenesis in cholangiopathic diseases such as BA.

A novel model of injured liver ductal organoids to investigate cholangiocyte apoptosis with relevance to biliary atresia

PURPOSE

The fibrogenic process in cholangiopathic diseases such as biliary atresia (BA) involves bile duct injury and apoptosis of cholangiocytes, which leads to the progression of liver fibrosis into liver cirrhosis and can result in end-staged liver disease. Recent advances in the development of organoids or mini-organ structures have allowed us to create an ex vivo injury model of the bile duct that mimics bile duct injury in BA. The aim of this experimental study was to develop a novel model of injured intrahepatic cholangiocytes as this can be relevant to BA. Our new model is important for studying the pathophysiological response of bile ducts to injury and the role of cholangiocytes in initiating the fibrogenic cascade. In addition, it has the potential to be used as a tool for developing new treatment strategies for BA.

METHODS

Liver ductal organoids were generated from the liver of healthy neonatal mouse pups. Intrahepatic bile duct fragments were isolated and cultured in Matrigel dome. Injury was induced in the organoids by administration of acetaminophen in culture medium. The organoids were then evaluated for fibrogenic cytokines expression, cell apoptosis marker and cell proliferation marker.

RESULTS

Organoids generated from intrahepatic bile duct fragments organized themselves into single-layer epithelial spheroids with lumen on the inside mimicking in vivo bile ducts. After 24-h exposure to acetaminophen, cholangiocytes in the organoids responded to the injury by increasing expression of fibrogenic cytokines, transforming growth factor beta-1 (TGF-β1) and platelet-derived growth factor-BB (PDGF-BB). This fibrogenic response of injured organoids was associated with increased cholangiocyte apoptosis and decreased cholangiocyte proliferation.

CONCLUSION

To our knowledge this is the first description of cholangiocyte injury in the organoids derived from intrahepatic bile ducts. Our injury model demonstrated that cholangiocyte apoptosis and its fibrogenic response may play a role in initiation of the fibrogenic process in cholangiopathic diseases such as BA. These findings are important for the development of novel therapy to reduce cholangiocyte apoptosis and to halt the early fibrogenic cascade in liver fibrogenesis. This novel injury model can prove very valuable for future research in biliary atresia.

Matrine promotes hepatic oval cells differentiation into hepatocytes and alleviates liver injury by suppression of Notch signalling pathway

AIMS

Recent studies have shown that the hyperactive Notch pathway is involved in cirrhosis and hepatocellular carcinoma (HCC) development by regulating differentiation of hepatic oval cells (HOCs) into cancer cells. The aim of this study was to investigate whether matrine can alleviate liver injury and promote HOC differentiation into hepatocytes by suppression of Notch pathway.

MAIN METHODS

We evaluated the expression of Notch-1, Jagged-1, and Hes-1 in HCC tissue by immunohistochemistry. Stem cell characteristics of HOCs were evaluated by CCK-8, cell cycle, and apoptosis. The expression of Notch pathway, HOC markers and albumin (ALB) was detected by immunohistochemistry, QRT-PCR and western blotting. The effects of matrine in protecting liver in vivo were investigated in a rat Solt-Farber precancerous model.

KEY FINDINGS

We found an abnormal activated Notch pathway in HCC tissue, and the hyperactive Notch pathway was strongly associated with poor liver function in patients with cirrhosis with HCC. Using siNotch-1 to inhibit Notch pathway confirmed that Notch pathway could maintain stem cell characteristics of HOCs. Matrine inhibited stem cell characteristics of HOCs, the expression of Notch pathway and HOC markers but upregulated ALB. Matrine in combined with siNotch-1 RNA decreased the more potently inhibited HOC markers and Notch pathway. In rat Solt-Farber precancerous model, prophylactic application of matrine alleviated liver injury, downregulated Notch pathway and HOC markers, and upregulated ALB in a dose-dependent manner.

SIGNIFICANCE

Matrine could promote the differentiation of HOCs into hepatocytes by inhibiting the Notch signalling pathway and alleviate liver injury.

TGF-β is associated with poor prognosis and promotes osteosarcoma progression via PI3K/Akt pathway activation

Transforming growth factor beta (TGF-β) is a multifunctional cytokine with important functions in cell proliferation and differentiation. TGF-β is highly expressed in several types of cancers and promotes tumor invasion and metastasis. However, the role of TGF-β in osteosarcoma progression is poorly understood. In the present study, we found that TGF-β is highly expressed in osteosarcoma cells and tissues, and is associated with high Ennecking stage (P = 0.033), metastasis, and recurrence. TGF-β-knockdown osteosarcoma cell lines were established using siRNA (si-TGF-β). Cells transfected with si-TGF-β exhibited significantly reduced proliferation, migration/invasion, and colony formation abilities, and increased levels of cell apoptosis. In addition, si-TGF-β treatment reduced spheroid size, the ratio of CD133-positive cells, and expression of SOX-2, Nanog, and Oct-3/4 in osteosarcoma cells. Mechanistically, PI3K/mTOR phosphorylation is inhibited by TGF-β knockdown. Pretreatment with 25 µM LY294002, a PI3K-specific inhibitor, further enhanced the si-TGF-β-induced suppression of osteosarcoma progression. Taken together, these results reveal a novel role for TGF-β in osteosarcoma progression and modulation of stemness-related traits and indicate that TGF-β may be of value as a therapeutic target for the treatment of osteosarcoma.

SOX9 enhances sorafenib resistance through upregulating ABCG2 expression in hepatocellular carcinoma

Sorafenib is a multi-kinase blocker and one of the few suggested drug treatments for aggressive hepatocellular carcinoma (HCC) patients. However, drug resistance to sorafenib may often occur over time and cause further tumor aggression. Recently, cancer stem cells were found in HCC and were speculated to be involved in tumor progression. SOX9 is highly expressed in HCC cancer stem cells and promotes cell proliferation and self-renewal. Meanwhile, HCC patients with higher SOX9 expression show poorer prognosis. Whether SOX9 is involved in sorafenib resistance in HCC is still unclear. Here, we found that sorafenib treatment increased the proportion of SOX9 positive cells in HCC cell lines. Overexpression of exogenous SOX9 in HCC increased sorafenib resistance both in vitro and in vivo, whereas down-regulation led to inhibition of sorafenib resistance. Knock-down of SOX9 by RNA interference caused down-regulation of downstream genes, including ATP binding cassette subfamily G member 2 (ABCG2). The drug resistance to sorafenib caused by SOX9 overexpression could be ameliorated by ABCG2 inhibition in HCC cell lines. In the cohort of patients taken sorafenib, we found that patients with lower SOX9 expression had more prolonged overall survival (OS) and progression-free survival (PFS). Univariate and multivariate Cox analysis shows that SOX9 expression exerts as an independent risk factor for the OS and PFS of HCC patients with sorafenib treatment. These findings demonstrate that SOX9 enhances sorafenib resistance and may regulate this process by modulating ABCG2 expression.

Biliary antibiotics irrigation for E. coli-induced chronic proliferative cholangitis and hepatolithiasis: A pathophysiological study in rabbits

BACKGROUND

The gram-negative bacteria secreted endotoxin, Lipopolysaccharide (LPS), plays important roles in the formation and recurrence of hepatolithiasis and chronic biliary inflammation in patients of Southeast Asia. We aimed to elucidate the anti-inflammatory effect and mechanism of local antibiotics irrigation on chronic proliferative cholangitis (CPC) and hepatolithiasis.

METHODS

Escherichia coli was injected into rabbit bile ducts to induce CPC. Rabbits were divided into sham operation (SO), povidone-iodine, Metronidazole plus chlorhexidine, ofloxacin, furacillin, Neosporin® G.U., and CPC groups. Local irrigation was performed for 28 days after CPC was established. Residual E. coli and LPS, and the expression of MCP-1, CD14, COX-2, VEGF, IL-6, NF-κB, TNF-α, Fas, TGF-β1, α-SMA, Collagen-I, β-glucuronidase, PKC, C-myc, and Mucin 5AC were assessed in bile duct tissues.

RESULTS

The residual E. coli and LPS, and expression of MCP-1, CD14, COX-2, IL-6, NF-κB, TNF-α, Fas, TGF-β1, α-SMA, β-glucuronidase, PKC, C-myc, and Mucin 5AC in the SO, povidone-iodine, Metronidazole plus chlorhexidine, ofloxacin, and Neosporin® G.U. groups were significantly lower than those in the furacillin and CPC groups (P<0.05). VEGF and Collagen-I levels in the SO, povidone-iodine, metronidazole plus chlorhexidine, and ofloxacin groups were significantly lower than those in the furacillin, Neosporin® G.U., and CPC groups (P<0.05).

CONCLUSIONS

LPS affects the pathophysiology of E. coli caused chronic proliferative cholangitis and hepatolithiasis recurrence. Local antibiotics irrigation could prevent chronic proliferative cholangitis and stones formation by decreasing LPS-induced proinflammatory and profibrotic cytokines release. Povidone iodine, metronidazole plus chlorhexidine, and ofloxacin were more effective than Neosporin® G.U. and furacillin.

The role of the sphingolipid pathway in liver fibrosis: an emerging new potential target for novel therapies

Sphingolipids (SL) are a family of bioactive lipids and a major cellular membrane structural component. SLs include three main compounds: ceramide (Cer), sphingosine (Sp), and sphingosine-1-phosphate (S-1P), all of which have emerging roles in biological functions in cells, especially in the liver. They are under investigation in various liver diseases, including cirrhosis and end-stage liver disease. In this review, we provide an overview on the role of SLs in liver pathobiology and focus on their potential role in the development of hepatic fibrosis. We describe recent evidence and suggest SLs are a promising potential therapeutic target for the treatment of liver disease and fibrosis.

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.

The Roles of Notch Signaling in Liver Development and Disease

The Notch signaling pathway plays major roles in organ development across animal species. In the mammalian liver, Notch has been found critical in development, regeneration and disease. In this review, we highlight the major advances in our understanding of the role of Notch activity in proper liver development and function. Specifically, we discuss the latest discoveries on how Notch, in conjunction with other signaling pathways, aids in proper liver development, regeneration and repair. In addition, we review the latest in the role of Notch signaling in the pathogenesis of liver fibrosis and chronic liver disease. Finally, recent evidence has shed light on the emerging connection between Notch signaling and glucose and lipid metabolism. We hope that highlighting the major advances in the roles of Notch signaling in the liver will stimulate further research in this exciting field and generate additional ideas for therapeutic manipulation of the Notch pathway in liver diseases.

Transforming growth factor-β signaling confers hepatic stellate cells progenitor features after partial hepatectomy

Liver regeneration involves not only hepatocyte replication but progenitor aggregation and scarring. Partial hepatectomy (PH), an established model for liver regeneration, reactivates transforming growth factor-β (TGF-β) signaling. Hepatic stellate cells (HSCs) are primarily responding cells for TGF-β and resident in stem cell niche. In the current study, PH mice were treated with SB-431542, an inhibitor of TGF-β Type I receptor, aiming to address the role of TGF-β signaling on the fate determination of HSCs during liver regeneration. After PH, control mice exhibited HSCs activation, progenitor cells accumulation, and a fraction of HSCs acquired the phenotype of hepatocyte or cholangiocyte. Blocking TGF-β signaling delayed proliferation, impaired progenitor response, and scarring repair. In SB-431542 group, merely no HSCs were found coexpressed progenitor makers, such as SOX9 and AFP. Inhibition of TGF-β pathway disturbed the epithelial-mesenchymal transitions and diminished the nuclear accumulation of β-catenin as well as the expression of cytochrome P450 2E1 in HSC during liver regeneration. We identify a key role of TGF-β signaling on promoting HSC transition, which subsequently becomes progenitor for generating liver epithelial cells after PH. This process might interact with an acknowledged stem cell function signaling, Wnt/β-catenin.

Function and regulation of transforming growth factor β1 signalling in antler chondrocyte proliferation and differentiation

OBJECTIVES

Chondrocyte proliferation and differentiation are crucial for endochondral ossification, but their regulatory mechanism remains unclear. The present study aimed to determine the physiological function of TGFβ1 signalling in the proliferation and differentiation of antler chondrocytes and explore its relationship with Notch, Shh signalling and Foxa.

MATERIALS AND METHODS

Immunofluorescence, Western blot, MTS assay, flow cytometry, RNA interference and real-time PCR were used to analyse the function and regulatory mechanisms of TGFβ1 signalling in antler chondrocyte proliferation and differentiation.

RESULTS

TGFβ1, TGFBR1 and TGFBR2 were highly expressed in antler cartilage. TGFβ1 promoted chondrocyte proliferation, increased the proportion of S-phase cells and induced the expression of hypertrophic chondrocyte markers Col X, Runx2 and Alpl. However, this induction was weakened by TGFβ receptor inhibitor SB431542 and Smad3 inhibitor SIS3. Simultaneously, TGFβ1 activated Notch and Shh signalling whose blockage attenuated the above effects of rTGFβ1, whereas addition of rShh rescued the defects in chondrocyte proliferation and differentiation elicited by SB431542 and SIS3. Further analysis revealed that inhibition of Notch signalling impeded TGFβ1 activation of the Shh pathway. Knockdown of Foxa1, Foxa2 and Foxa3 abrogated the effects of TGFβ1 on chondrocyte differentiation. Notch and Shh signalling mediated the regulation of Foxa transcription factors by TGFβ1.

CONCLUSIONS

TGFβ1 signalling could induce the proliferation and differentiation of antler chondrocytes through Notch-Shh-Foxa pathway.

Primary Sclerosing Cholangitis: A Concise Review of Diagnosis and Management

Primary sclerosing cholangitis is a rare, chronic cholestatic liver disease characterized by progressive idiopathic stricturing of the biliary system, typically leading to cirrhosis, end-stage liver disease, and colonic or hepatobiliary malignancy. Its presentation is often that of asymptomatic alkaline phosphatase elevation. When symptoms are present, they typically include fatigue, pruritus, or jaundice. The diagnosis can be confirmed via cholangiography, either magnetic resonance cholangiography (MRCP) or endoscopic retrograde cholangiography if the former is inconclusive. The clinical course is marked by progressive liver disease leading to cirrhosis with its attendant complications of portal hypertension, often including recurrent episodes of cholangitis. Greater elevation in alkaline phosphatase or liver stiffness is associated with worse clinical outcomes. Management includes endoscopic treatment of symptomatic biliary strictures and evaluation of dominant strictures as no adequate medical treatment is available. Multiple medical therapies are under evaluation. Ultimately, liver transplantation may be necessary for management of decompensated cirrhosis or disabling symptoms. There is also a markedly increased risk of cancer, notably including cholangiocarcinoma and gallbladder and colorectal cancers (particularly in patients with colitis). Cancer screening can be done with semi-annual liver imaging (MRCP or ultrasound) and colonoscopy every 1-2 years in those with colitis.

Downregulated microRNA-330 suppresses left ventricular remodeling via the TGF-β1/Smad3 signaling pathway by targeting SRY in mice with myocardial ischemia-reperfusion injury

microRNAs (miRs) are essential in the development of heart failure. The aim of this study is to investigate the effect of microRNA-330 (miR-330) on left ventricular remodeling via the TGF-β1/Smad3 signaling pathway by targeting the sex-determining region Y (SRY) in mice with myocardial ischemia-reperfusion injury (MIRI). Differentially expressed gene (DEG) in myocardial ischemia-reperfusion (IR) was screened out and the miR that targeted the DEG was also predicted and verified. A model of MIRI was established to detect the expression of miR-330, SRY, transforming growth factor-β (TGF-β1), and Sekelsky mothers against dpp3 (Smad3). To further investigate the role of miR-330 in MIRI with the involvement of SRY and TGF-β1/Smad3 signaling pathway, the modeled mice were treated with different mimic, inhibitor, or small interfering RNA (siRNA) to observe the changes of the related gene expression, as well as the myocardial infarction size and volume of myocardial collagen. SRY was screened out and verified as a target gene of miR-330. The MIRI mice showed enlarged myocardial infarction size, increased volume of myocardial collagen, increased expression of miR-330, TGF-β1 and Smad3, while decreased the expression of SRY. The MIRI mice treated with miR-330 inhibitor showed decreased myocardial infarction size, the volume of myocardial collagen, and expression of TGF-β1 and Smad3 but promoted expression of SRY. Our findings demonstrated that downregulated miR-330 could suppress left ventricular remodeling to inhibit the activation of the TGF-β1/Smad3 signaling pathway via negatively targeting of SRY in mice with MIRI. This can be a potential target in the strategy to attenuate patient suffering.

Hepatic stellate cells regulate hepatic progenitor cells differentiation via the TGF-β1/Jagged1 signaling axis

Hepatic stellate cells (HSCs) play an important microenvironmental role in hepatic progenitor cells (HPCs) differentiation fate. To reveal the specific mechanism of HSCs induced by transforming growth factor β1 (TGF-β1) signaling in HPCs differentiation process, we used Knockin and knockdown technologies induced by lentivirus to upregulate or downregulate TGF-β1 level in mouse HSCs (mHSCs) (mHSCs-TGF-β1 or mHSCs-TGF-βR1sih3). Primary mouse HPCs (mHPCs) were isolated and were cocultured with mHSCs-TGF-β1 and mHSCs-TGF-βR1sih3 for 7 days. Differentiation of mHPCs was detected by quantitative reverse transcriptase polymerase chain reaction analysis and immunofluorence in vitro. mHPCs-E_14.5 cell lines and differently treated mHSCs were cotransplanted into mice spleens immediately after establishment of acute liver injury model for animal studies. Engraftment and differentiation of transplanted cells as well as liver function recovery were measured at the seventh day via different methods. mHSCs-TGF-β1 were transformed into myofibroblasts and highly expressed Jagged1, but that expression was reduced after blockage of TGF-β1 signaling. mHPCs highly expressed downstream markers of Jagged1/Notch signaling and cholangiocyte markers (CK19, SOX9, and Hes1) after coculture with mHSCs-TGF-β1 in vitro. In contrast, mature hepatocyte marker (ALB) was upregulated in mHPCs in coculture conditions with mHSCs-TGF-βR1sih3. At the seventh day of cell transplantation assay, mHPCs-E _14.5 engrafted and differentiated into cholangiocytes after cotransplanting with TGF-β1-knockin mHSCs, but the cells had a tendency to differentiate into hepatocytes when transplanted with TGF-βR1-knockdown mHSCs, which corresponded to in vitro studies. HSCs play an important role in regulating HPCs differentiation into cholangiocytes via the TGF-β1/Jagged1 signaling axis. However, HPCs have a tendency to differentiate into hepatocytes after blockage of TGF-β1 signaling in HSCs.