TGFβ signaling controls intrahepatic bile duct development may through regulating the Jagged1‐Notch‐Sox9 signaling axis

Diverse functions of SOX9 in liver development and homeostasis and hepatobiliary diseases

The liver is the central organ for digestion and detoxification and has unique metabolic and regenerative capacities. The hepatobiliary system originates from the foregut endoderm, in which cells undergo multiple events of cell proliferation, migration, and differentiation to form the liver parenchyma and ductal system under the hierarchical regulation of transcription factors. Studies on liver development and diseases have revealed that SRY-related high-mobility group box 9 (SOX9) plays an important role in liver embryogenesis and the progression of hepatobiliary diseases. SOX9 is not only a master regulator of cell fate determination and tissue morphogenesis, but also regulates various biological features of cancer, including cancer stemness, invasion, and drug resistance, making SOX9 a potential biomarker for tumor prognosis and progression. This review systematically summarizes the latest findings of SOX9 in hepatobiliary development, homeostasis, and disease. We also highlight the value of SOX9 as a novel biomarker and potential target for the clinical treatment of major liver diseases.

To observe the clinical effect of lipoic acid combined with continuous positive airway pressure ventilation in treating obstructive sleep apnea-hypopnea syndrome and its effect on peripheral blood γ-aminobutyric acid and melatonin levels

BACKGROUND

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a common respiratory disease with potential lethality. At present, the commonly used treatment method is continuous positive airway pressure ventilation, but with the prolongation of the course of the disease, the effect of single ventilation on the improvement of oxidative stress levels is not good. Lipoic acid is a commonly used antioxidant in clinics. In this paper, lipoic acid combined with continuous positive airway pressure ventilation is used to explore whether it has a better therapeutic effect on patients.

AIM

To probe into the clinical efficacy of lipoic acid combined with continuous positive airway pressure ventilation in the therapy of OSAHS.

METHODS

82 patients with OSAHS who were cured in our hospital from March 2021 to September 2022 were prospectively collected as subjects. Based on different treatment methods, patients were grouped into a control group (43 cases) and an observation group (39 cases). The control group was treated with continuous positive airway pressure (CPAP), and the observation group was treated with lipoic acid based on control group. The therapeutic effects were measured by apnea hypopnea index (AHI), oxygen saturation (SpO2), mean oxygen saturation (MSpO2), serum malondialdehyde (MDA), superoxide dismutase (SOD), hypoxia inducible factor-1α (HIF-1α) levels, peripheral blood γ-aminobutyric acid, melatonin levels.

RESULTS

The clinical effectiveness of the observation group was better (P < 0.05). After treatment, AHI, the levels of MDA and HIF-1α in the observation group were lower and SpO2, MSpO2 and the level of SOD, γ- aminobutyric acid, and melatonin were higher than those in the control group (P < 0.05). The levels of γ- aminobutyric acid and melatonin were negatively correlated with the severity of symptoms, ESS, and AIS scores (P < 0.05).

CONCLUSIONS

The clinical effect of lipoic acid combined with CPAP in the treatment of OSAHS is better, and it has a positive effect on the levels of γ-aminobutyric acid and melatonin in peripheral blood. Lipoic acid was added to the original method for treatment, and the therapeutic effect was greatly improved.

Biliary atresia: the development, pathological features, and classification of the bile duct

Biliary atresia is an occlusive biliary disease involving intrahepatic and extrahepatic bile ducts. Its etiology and pathogenesis are unclear. There are many manifestations of bile duct involvement in biliary atresia, but little is known about its occurrence and development. In addition, different classification methods have been proposed in different periods of biliary atresia, each with its advantages and disadvantages. The combined application of biliary atresia classification will help to improve the survival rate of patients with native liver. Therefore, this article reviews the development, pathological features, and classification of intrahepatic and extrahepatic bile ducts in biliary atresia, to provide a reference for the study of the pathogenesis and the choice of treatment methods.

Liver Explants of Biliary Atresia Patients Transplanted in Adulthood Show Features of Obliterative Portal Venopathy: Case Series and Guidelines for Pathologic Reporting of Adult Explants

CONTEXT.—

Biliary atresia (BA) patients can have portal vein (PV) abnormalities.

OBJECTIVE.—

To investigate the explant pathology of BA patients transplanted in adulthood with a focus on portal venous abnormalities.

DESIGN.—

Adult BA liver explants were reviewed, along with prior biopsies, Kasai portoenterostomy (KP), and relevant medical records.

RESULTS.—

Three explants were identified; all patients were female, with age at diagnosis, KP, and liver transplantation (LT) as follows: (1) less than 1 week, 8 days, and 25 years; (2) 15 weeks, 16 weeks, and 32 years; and (3) 7 weeks, 8 weeks, and 33 years, respectively, with normalization of conjugated bilirubin within 6 months of KP and development of portal hypertension (PHTN) within 3 years of KP for all 3. The first 2 had recurrent cholangitis. Duration of pre-LT PHTN was 22, 29, and 30 years, and that of pre-LT cholangitis was 9, 3, and 0 years, respectively. All 3 explants showed hilar and extrahepatic fibromyxoid intimal hyperplasia of the PV with parenchymal hepatoportal sclerosis. Cholestasis was limited to those with a history of cholangitis. Patient 3, without cholangitis, showed delicate septal fibrosis with peripheral accentuation without biliary cirrhosis.

CONCLUSIONS.—

In the context of a functioning KP, cholestasis and biliary cirrhosis are likely related to recurrent cholangitis, which may or may not occur after KP. In the absence of biliary cirrhosis, PHTN may be secondary to obliterative venopathy. Adult BA explants should be sampled thoroughly, with a focus on hilar/perihilar connective tissue to include PV branches. Explants may not show biliary cirrhosis and should be reported with appropriate clinicopathologic correlation.

Exosomes derived from TGF-β1-pretreated mesenchymal stem cells alleviate biliary ischemia-reperfusion injury through Jagged1/Notch1/SOX9 pathway

BACKGROUND

This study aimed to evaluate the efficacy of exosomes (EXO) derived from TGF-β1-pretreated mesenchymal stem cells (MSCs) on biliary ischemia reperfusion injury (IRI) and further reveal the possible mechanisms.

METHODS

Bone marrow-derived MSCs were treated with exogenous TGF-β1, Jagged1/Notch1/SOX9 pathway inhibitor LY450139, or their combination. Then, EXO were isolated from the culture supernatants and further characterized. After establishing IRI model of biliary epithelial cells (EpiCs), EXO derived from differently-treated MSCs were applied to detect their protective effects on EpiCs, and LY450139 was applied in EpiCs to detect the possible mechanisms after treatment with MSCs-EXO. EXO derived from differently-treated MSCs were further injected into the hepatic artery immediately after establishment of intrahepatic biliary IRI for animal studies.

RESULTS

Pretreatment with TGF-β1 significantly enhanced MSCs-EXO production and elevated the levels of massive miRNAs associated with anti-apoptosis and tissue repair, which were evidently decreased after TGF-β1 plus LY450139 cotreatment. Notable improvement was observed in EpiCs after MSCs-EXO treatment, evidenced by reduced cellular apoptosis, increased cellular proliferation and declined oxidative stress, which were more evident in EpiCs that were treated with EXO derived from TGF-β1-pretreated MSCs. However, application of EXO derived from TGF-β1 plus LY450139-cotreated MSCs reversely enhanced cellular apoptosis, decreased cellular proliferation and anti-oxidants production. Interestingly, LY450139 application in EpiCs after treatment with MSCs-EXO also reversed the declined cellular apoptosis and enhanced oxidative stress induced by TGF-β1 pretreatment. In animal studies, administration of EXO derived from TGF-β1-pretreated MSCs more effectively attenuated biliary IRI through reducing oxidative stress, apoptosis, inflammation and enhancing the expression levels of TGF-β1 and Jagged1/Notch1/SOX9 pathway-related markers, which were reversed after administration of EXO derived from TGF-β1 plus LY450139-cotreated MSCs.

CONCLUSION

Our results provided a vital insight that TGF-β1 pretreatment endowed MSCs-EXO with stronger protective effects to improve biliary IRI via Jagged1/Notch1/SOX9 pathway.

Sox9 is required in regeneration of pancreatic β cells following injury

The reduction of insulin secretion due to pancreatic β cell injury caused by autoimmune reaction is the pathological basis of Type 1 diabetes mellitus (T1DM). Therefore, seeking new molecular targets for alleviating pancreatic β cell injury will provide experimental basis for the prevention and treatment of T1DM. SRY-box 9 (Sox9) is not only an important molecule regulating the development of various organs, but also its high expression can aggravate the pathological process of various diseases. In addition, Sox9⁺ cells are also pancreatic progenitor cells, participating in pancreatic repair reaction induced by injury. In our study, elevated blood glucose and lack of pancreatic β cells almost returned to normal over time after streptozotocin (STZ)-induced pancreatic β cell damage, implying that pancreatic β cells were regenerated after STZ-induced injury. In particular, the expression of Sox9 was significantly elevated during pancreatic β cell regeneration. On this basis, we conducted in vitro experiments to verify whether overexpression of Sox9 could inhibit the damage of pancreatic β cells by inflammatory factors. Our results showed that overexpression of Sox9 alleviated the damage of pancreatic β cells by inflammatory factors and improved the inhibitory effect of inflammatory factors on insulin secretion of pancreatic β cells. Unsurprising, blood glucose levels, insulin content and pancreatic β cell number failed to return to near-normal levels timely after pancreatic β cells specific knockout Sox9 mice were treated with STZ, further confirming the importance of Sox9 in facilitating pancreatic β cell repair or regeneration. Our study indicate that enhanced Sox9 activity might protect pancreatic β cells from autoimmune induced damage and thus improve the pathological process of T1DM.

Dynamics of hepatocyte-cholangiocyte cell-fate decisions during liver development and regeneration

The immense regenerative potential of the liver is attributed to the ability of its two key cell types – hepatocytes and cholangiocytes – to trans-differentiate to one another either directly or through intermediate progenitor states. However, the dynamic features of decision-making between these cell-fates during liver development and regeneration remains elusive. Here, we identify a core gene regulatory network comprising c/EBPα, TGFBR2, and SOX9 which is multistable in nature, enabling three distinct cell states – hepatocytes, cholangiocytes, and liver progenitor cells (hepatoblasts/oval cells) – and stochastic switching among them. Predicted expression signature for these three states are validated through multiple bulk and single-cell transcriptomic datasets collected across developmental stages and injury-induced liver repair. This network can also explain the experimentally observed spatial organization of phenotypes in liver parenchyma and predict strategies for efficient cellular reprogramming. Our analysis elucidates how the emergent dynamics of underlying regulatory networks drive diverse cell-fate decisions in liver development and regeneration.

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Identified minimal regulatory network to model liver development and regeneration

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Changes in phenotypic landscapes by in-silico perturbations of regulatory networks

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Ability to explain physiological spatial patterning of liver cell types

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Decoded strategies for efficient reprogramming among liver cell phenotypes

IL-7-Treated Periodontal Ligament Cells Regulate Local Immune Homeostasis by Modulating Treg/Th17 Cell Polarization

Both interleukin (IL)-7 and human periodontal ligament cells (hPDLCs) have immunomodulatory properties. However, their combined effect on CD4⁺T cells has never been studied. In this study, we aimed to investigate the effect of conditioned medium of hPDLCs treated with rhIL-7 on the differentiation of CD4⁺T cells into regulatory T cells/T helper 17 cells (Treg/Th17 cells) and observe the effect of IL-7 on the immunomodulatory properties of PDLCs. After hPDLCs were treated with different concentrations of rhIL-7 for 24 h, the collected supernatants were used to incubate CD4⁺T cells for 3 days. A gamma-secretase inhibitor (DAPT) was used to suppress the activation of the Notch1 signaling pathway. Cell proliferation, apoptosis, and necrosis were determined using the cell counting kit-8 (CCK-8) and flow cytometry (FCM). The expressions of forkhead box P3 (Foxp3) in CD4⁺T cells and transforming growth factor (TGF-β) and IL-6 in the supernatants were determined by ELISA. Reverse transcription-quantitative PCR (RT-qPCR), and the Western blot (WB) determined the mRNA levels and protein expression of various target factors. FCM was used to detect the mean fluorescence intensity of PD-L1 in hPDLCs and to analyze the differentiation of Treg/Th17 cells. Our results showed that IL-7 promoted proliferation and inhibited apoptosis in hPDLCs, promoted the expression of TGF-β, PD-L1, Notch1, Jagged1, and Hes1, and inhibited the levels of hypoxia-inducible factor (HIF)-1α and TCF7, whereas the addition of DAPT effectively reversed these effects. Importantly, we found that the conditioned medium of hPDLCs treated with rhIL-7 promoted the polarization of CD4⁺T cells into Treg cells but had no significant effect on the differentiation of Th17 cells. Our study indicated that treatment of PDLCs with IL-7 can promote the polarization of CD4⁺T cells into Treg cells by modulating the expression of inflammatory factors and signaling molecules through activating the Notch1 signaling pathway, thus participating in the regulation of immune homeostasis in the periodontal microenvironment.

Wnt signaling in biliary development, proliferation, and fibrosis

Biliary fibrosis is an important pathological indicator of hepatobiliary damage. Cholangiocyte is the key cell type involved in this process. To reveal the pathogenesis of biliary fibrosis, it is essential to understand the normal development as well as the aberrant generation and proliferation of cholangiocytes. Numerous reports suggest that the Wnt signaling pathway is implicated in the physiological and pathological processes of cholangiocyte development and ductular reaction. In this review, we summarize the effects of Wnt pathway in cholangiocyte development from embryonic stem cells, as well as the underlying mechanisms of cholangiocyte responses to adult ductal damage. Wnt signaling pathway is regulated in a step-wise manner during each of the liver differentiation stages from embryonic stem cells to functional mature cholangiocytes. With the modulation of Wnt pathway, cholangiocytes can also be generated from adult liver progenitor cells and mature hepatocytes to repair liver damage. Non-canonical Wnt signaling is triggered in the active ductal cells during biliary fibrosis. Targeted control of the Wnt signaling may hold the great potential to reduce and/or reverse the biliary fibrogenic process.

Connexin Expression Is Altered in Liver Development of Yotari (dab1 -/-) Mice

Disabled-1 (Dab1) protein is an intracellular adaptor of reelin signaling required for prenatal neuronal migration, as well as postnatal neurotransmission, memory formation and synaptic plasticity. Yotari, an autosomal recessive mutant of the mouse Dab1 gene is recognizable by its premature death, unstable gait and tremor. Previous findings are mostly based on neuronal abnormalities caused by Dab1 deficiency, but the role of the reelin signaling pathway in nonneuronal tissues and organs has not been studied until recently. Hepatocytes, the most abundant cells in the liver, communicate via gap junctions (GJ) are composed of connexins. Cell communication disruption in yotari mice was examined by analyzing the expression of connexins (Cxs): Cx26, Cx32, Cx37, Cx40, Cx43 and Cx45 during liver development at 13.5 and 15.5 gestation days (E13.5 and E15.5). Analyses were performed using immunohistochemistry and fluorescent microscopy, followed by quantification of area percentage covered by positive signal. Data are expressed as a mean ± SD and analyzed by one-way ANOVA. All Cxs examined displayed a significant decrease in yotari compared to wild type (wt) individuals at E13.5. Looking at E15.5 we have similar results with exception of Cx37 showing negligible expression in wt. Channels formation triggered by pathological stimuli, as well as propensity to apoptosis, was studied by measuring the expression of Pannexin1 (Panx1) and Apoptosis-inducing factor (AIF) through developmental stages mentioned above. An increase in Panx1 expression of E15.5 yotari mice, as well as a strong jump of AIF in both phases suggesting that yotari mice are more prone to apoptosis. Our results emphasize the importance of gap junction intercellular communication (GJIC) during liver development and their possible involvement in liver pathology and diagnostics where they can serve as potential biomarkers and drug targets.

Maladaptive regeneration - the reawakening of developmental pathways in NASH and fibrosis

With the rapid expansion of the obesity epidemic, nonalcoholic fatty liver disease is now the most common chronic liver disease, with almost 25% global prevalence. Nonalcoholic fatty liver disease ranges in severity from simple steatosis, a benign 'pre-disease' state, to the liver injury and inflammation that characterize nonalcoholic steatohepatitis (NASH), which in turn predisposes individuals to liver fibrosis. Fibrosis is the major determinant of clinical outcomes in patients with NASH and is associated with increased risks of cirrhosis and hepatocellular carcinoma. NASH has no approved therapies, and liver fibrosis shows poor response to existing pharmacotherapy, in part due to an incomplete understanding of the underlying pathophysiology. Patient and mouse data have shown that NASH is associated with the activation of developmental pathways: Notch, Hedgehog and Hippo-YAP-TAZ. Although these evolutionarily conserved fundamental signals are known to determine liver morphogenesis during development, new data have shown a coordinated and causal role for these pathways in the liver injury response, which becomes maladaptive during obesity-associated chronic liver disease. In this Review, we discuss the aetiology of this reactivation of developmental pathways and review the cell-autonomous and cell-non-autonomous mechanisms by which developmental pathways influence disease progression. Finally, we discuss the potential prognostic and therapeutic implications of these data for NASH and liver fibrosis.

Direct effects of transforming growth factor-β1 signaling on the differentiation fate of fetal hepatic progenitor cells

Aim: To investigate direct roles of TGF-β1 signaling in the differentiation process of fetal hepatic progenitor cells (HPCs). Materials & methods: Exogenous TGF-β1 and SB431542 were added into fetal HPCs. Then, SB431542 was intraperitoneally injected into pregnant mice for 8 days. Results: Fetal HPCs treated with TGF-β1 differentiated into cholangiocytes. However, hepatocyte marker was highly expressed after inhibiting TGF-β1 signaling. In vivo, hematopoietic cells were gradually replaced with liver cells and TGF-β1 expression was evidently decreased as fetal liver developed. Inhibition of TGF-β1 signaling caused increase of ALB⁺ cells, but CK19 expression was more obvious in control mice livers. Conclusion: TGF-β1 signaling may play decisive roles in fetal HPCs differentiation into functional hepatocytes or cholangiocytes.

Biliary Atresia Patients With Successful Kasai Portoenterostomy Can Present With Features of Obliterative Portal Venopathy

OBJECTIVE

Study of liver explants of biliary atresia (BA) patients with successful Kasai portoenterostomy (KP).

METHODS

Pathology and medical records of BA liver explants from January 2009 to June 2018 with successful KP were reviewed along with appropriate controls.

RESULTS

Fourteen out of 68 (20.6%) BA patients with LT had a successful KP. Median age at BA diagnosis, KP and LT was 60.5 days, 61 days, and 10 years, respectively, with conjugated bilirubin (c-bil) normalizing at 12.5 weeks after KP. Advanced fibrosis was diffuse in 2/14 (14.3%) explants, limited to periphery in 11/14 (78.6%) and absent in 1. Hilar partial nodular transformation (PNT) was seen in 11 explants (78.6%) and diffuse nodular regenerative hyperplasia (NRH) in 2 (14.3%). Areas of PNT and NRH showed diffuse portal sclerosis (100%), complete and incomplete portal vein (PV) stenosis (100%), PV herniation (100%), hypervascular portal tracts (20%), periportal abnormal vessels (100%), abundant lymphatic collaterals (100%), mild medial hepatic arterial hypertrophy (100%), and delicate fibrous septae (100%). Extrahepatic PVs showed variable luminal occlusion with mean PV intima to full thickness ratio of 0.6 +/- 0.11; significantly higher than age-matched noncirrhotic (n = 27, 0.08 +/- 0.09; P < 0.0001) and cirrhotic controls (n = 19, 0.34 +/- 0.2; P = 0.0015); and comparable to BA patients with failed KP (P = 0.82) and without KP (P = 0.04).

CONCLUSIONS

BA patients with successful KP can present with obliterative portal venopathy (OPV). In the context of optimal bile drainage, portal hypertension may not be because of advanced parenchymal fibrosis but possibly because of OPV. Vascular abnormalities of the PV system should be investigated in BA patients.

The local and circulating SOX9 as a potential biomarker for the diagnosis of primary bone cancer

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The SOX9 expression increased in tumor tissues and peripheral blood of malignant and benign bone tumors.

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The protein level of SOX9 is enhanced in malignant bone tumor tissues.

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SOX9 over-expression correlated with tumor severity, grade, invasion feature, poor response to therapy, and recurrence.

Purpose

The status of the local and circulating SOX9, a master regulator of the tumor fate, and its relevance to tumor types, severity, invasion feature, response to therapy, and chemotherapy treatment were surveyed in bone cancer in the current study.

Methods

The SOX9 expression level was evaluated in tissue and peripheral blood mononuclear cells from patients with different types of malignant and benign bone tumors also tumor margin tissues using Real-Time PCR. The protein level of SOX9 was assessed using immunohistochemistry and western blot analysis. Also, the correlations of the SOX9 expression level with the patient’s clinical and pathological features were considered.

Results

The remarkable overexpression of SOX9 was detected in bone tumors compared to tumor margin tissues (P < 0.0001). Malignant bone tumors revealed a higher expression of SOX9 compared to benign tumors (P < 0.0001) while osteosarcoma tumors showed higher expression levels compared to Ewing sarcoma, and chondrosarcoma. Overexpression of SOX9 was observed in high grade, metastatic, recurrent tumors also tumors with poor response to therapy. Besides, the patients under the chemotherapy treatment demonstrated higher levels of SOX9 compared to the rest of malignant tumors (P = 0.02). The simultaneous up-regulation of circulating SOX9 in the patients with bone cancer was observed compared to healthy individuals (P < 0.0001) accompanying with overexpression of SOX9 in malignant tumors compared to benign tumors (P < 0.0001). The circulating SOX9 expression was up-regulated in the patients with malignant bone tumors who receive chemotherapy treatment also patients with high grade, metastatic, recurrent tumors. The protein level of SOX9 was in line with our data on the SOX9 gene expression.

Conclusion

The simultaneous overexpression of local and circulating SOX9 in bone cancer besides its positive correlation with tumor severity, malignancy, size, and chemotherapy may deserve receiving more attention in bone cancer diagnosis and therapy.

Molecular cloning, characterization, mRNA expression changes and nucleocytoplasmic shuttling during kidney embryonic development of SOX9 in Alligator sinensis

SOX9 plays a crucial, extensive and conservative role in the process of somatic tissue development and adult regeneration through the positive self-regulation mediated by SOM across all vertebrates. In this study, we have cloned SOX9 from the kidney of hatchling Alligator sinensis. The full-length of SOX9 cDNA is 3878 bp with an open reading frame encoding 494 amino acids. Amino acid alignment analyses indicated that the SOX9 exhibit highly conserved functional domains. Using the droplet digital PCR, the mRNA abundances of SOX9 during nephrogenesis in A. sinensis showed prominent changes in the embryonic development, suggesting that SOX9 might combines a vital role in the regulation of complex renal development. Interestingly, we detected the nucleocytoplasmic shuttling of SOX9 protein using immunofluorescence, implying that nucleocytoplasmic shuttling is critical to the regulation of SOX9 in the renal embryonic development. Collectively, these data provide an important foundation for further studies on renal developmental biology and molecular biology of non-mammalian SOX9. Furthermore, it provides new insights into the phenomenon of SOX9 nucleocytoplasmic shuttling in Alligator sinensis, which is probably of great significance to the development of kidney metanephros embryo.

TGF-β Signaling Plays a Pivotal Role During Developmental Biliary Atresia in Sea Lamprey (Petromyzon marinus)

Biliary atresia (BA) is a rare neonatal disease with unknown causes. Approximately 10% of BA cases develop in utero with other congenital defects that span a large spectrum of disease variations, including degeneration of the gall bladder and bile duct as well as malformation of the liver, intestines, and kidneys. Similar developmental alterations are manifested in a unique animal model, the sea lamprey (Petromyzon marinus), in which BA occurs naturally during metamorphosis. With the likelihood of conserved developmental mechanisms underlying organogenesis and degeneration, lamprey developmental BA may be a useful model to infer mechanisms underlying human embryonic BA. We reasoned that hepatobiliary transcriptomes regulate the transition between landmark stages of BA. Therefore, we examined sea lamprey hepatobiliary transcriptomes at four stages (M0, metamorphic stage 0 or larval stage, no BA; M2, metamorphic stage 2, onset of BA; M5, metamorphic stage 5, BA, and heightened hepatocyte proliferation and reorganization; and JV, juvenile, completion of BA) using messenger RNA sequencing and Kyoto Encyclopedia of Genes and Genomes pathway analyses. We found gene-expression patterns associated with the transition between these stages. In particular, transforming growth factor β (TGF-β), hedgehog, phosphatidylinositol-4,5-bisphosphate 3-kinase-Akt, Wnt, and mitogen-activated protein kinase pathways were involved during biliary degeneration. Furthermore, disrupting the TGF-β signaling pathway with antagonist or small interfering RNA treatments at the onset of BA delayed gall bladder and bile duct degeneration. Conclusion: Distinctive gene-expression patterns are associated with the degeneration of the biliary system during developmental BA. In addition, disrupting TGF-β signaling pathway at the onset of BA delayed biliary degeneration.

Myofibroblasts control the proliferation of fetal hepatoblasts and their differentiated cholangiocytes during the hepatoblast-to-cholangiocyte transition

Mesenchymal cells in the liver provide the microenvironment for hepatoblasts expansion and differentiation. We have previously demonstrated that myofibroblasts (MFs) promoted hepatoblasts differentiation into cholangiocytes, whereas its role in controlling the proliferation of hepatoblasts and their differentiated cholangiocytes remains elusive. Here, we investigated the role of MFs in regulating the proliferation of hepatoblasts and their differentiated cholangiocytes using an indirect coculture system. When cocultured with hepatoblasts, MFs promoted hepatoblasts differentiation into cholangiocytes and inhibited the proliferation and stemness of hepatoblasts. However, when hepatoblasts already differentiated into cholangiocytes, MFs promoted the differentiated cholangiocytes proliferation. In addition, hepatoblast proliferation genes such as hepatocyte growth factor (HGF), insulin-like growth factor-1 and 2 (IGF-1 and 2), midkine 1 (Mdk1), and pleiotrophin (Ptn) expression in MFs were down-regulated compared with their levels in fibroblasts. Our findings uncover the role of MFs in controlling the proliferation of hepatoblasts and their differentiated cholangiocytes, potentially providing a novel therapeutic strategy for cholangiocyte regeneration.

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.

TGF-β1 signaling activates hepatic stellate cells through Notch pathway

Hepatic stellate cells (HSCs), as the most important stromal cells in the liver microenvironment, play crucial roles in hepatic fibrosis, hepatocellular carcinoma, liver regeneration and fetal liver development after transdifferentiating into myofibroblasts (MFs). Transforming growth factor β1 (TGF-β1), as an important polyergic cytokine, is involved in HSCs activation process. However, the specific mechanisms of HSCs transdifferentiation process are not clearly demonstrated. Here we added exogenous recombinant TGF-β1 protein and transforming growth factor β receptor 1 (TGF-βR1) inhibitor SB431542 into mouse HSCs to detect the detailed impact of TGF-β1 signaling on HSCs activation. TGF-β1 signaling significantly increased phosphorylated (P)-Smad2/3 level and promoted Smad2/3 translocation from the cytoplasm to the nucleus, which also caused transdifferentiation of HSCs into MFs. Importantly, TGF-β1 signaling also resulted in high expression of Notch pathway markers Notch1, Jagged1, Hes1 in HSCs. In contrast, expression of those above markers in mouse HSCs were obviously decreased after hampering TGF-β1 signaling via TGF-βR1 inhibitor SB431542. To further examine the effect of Notch pathway on HSCs activation process, TGF-β1-stimulated HSCs and control HSCs were treated with or without LY450139, a specific inhibitor of Notch pathway. LY450139 evidently decreased the expression of Notch1 and MFs marker α-smooth muscle actin (α-SMA) expression in HSCs. These above results may provide a novel insight that TGF-β1 signaling controls HSCs activation process through regulating the expression of Notch pathway markers.

Development of the Intrahepatic and Extrahepatic Biliary Tract: A Framework for Understanding Congenital Diseases

The involvement of the biliary tract in the pathophysiology of liver diseases and the increased attention paid to bile ducts in the bioconstruction of liver tissue for regenerative therapy have fueled intense research into the fundamental mechanisms of biliary development. Here, I review the molecular, cellular and tissular mechanisms driving differentiation and morphogenesis of the intrahepatic and extrahepatic bile ducts. This review focuses on the dynamics of the transcriptional and signaling modules that promote biliary development in human and mouse liver and discusses studies in which the use of zebrafish uncovered unexplored processes in mammalian biliary development. The review concludes by providing a framework for interpreting the mechanisms that may help us understand the origin of congenital biliary diseases.

Curcumin Can Improve Spinal Cord Injury by Inhibiting TGF-β-SOX9 Signaling Pathway

Spinal cord injury (SCI) is a severe nervous system disease with high morbidity and disability rate. Signaling pathways play a key role in the neuronal restorative mechanism following SCI. SRY-related high mobility group (HMG)-box gene 9 (SOX9) affects glial scar formation via Transforming growth factor beta (TGF-β) signaling pathway. Activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is transferred into nucleus to upregulate TGF-β-SOX9. Curcumin exhibits potent anti-inflammatory and anti-oxidant properties. Curcumin can play an important role in SCI recovery by inhibiting the expression of NF-κB and TGF-β-SOX9. Herein, we review the potential mechanism of curcumin-inhibiting SOX9 signaling pathway in SCI treatment. The inhibition of NF-κB and SOX9 signaling pathway by curcumin has the potentiality of serving as neuronal regenerative mechanism following SCI.

Direct and indirect coculture of mouse hepatic progenitor cells with mouse embryonic fibroblasts for the generation of hepatocytes and cholangiocytes

The widespread use of hepatocytes and cholangiocytes for regenerative medicine and tissue engineering is restricted by the limited number of hepatocytes and cholangiocytes; a simple and effective method for the expansion and differentiation of the hepatic progenitor cells (HPCs) is required. Recent studies demonstrated that mouse embryonic fibroblasts (MEFs) play an important role in supporting the proliferation of the mouse hepatic progenitor cells (mHPCs). However, the effect of direct and indirect coculture of MEFs with mHPCs on the differentiation of mHPCs is poorly studied. Herein, we show that mHPCs rapidly proliferate and form colonies in direct or indirect contact coculture with MEFs in the serum-free medium. Importantly, after direct contact coculture of the mHPCs with MEFs for 6 days, mHPCs expressed the hepatic marker albumin (ALB) and did not express the cholangiocyte marker CK19, indicating their differentiation into hepatocytes. In contrast, after indirect contact coculture of the mHPCs with MEFs for 6 days, mHPCs expressed the cholangiocyte marker CK19 and did not express the hepatic marker ALB, indicating their differentiation into cholangiocytes. These results indicate that direct and indirect contact cocultures of the mHPCs with MEFs are useful for rapidly producing hepatocytes and cholangiocytes.

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.

The contributions of mesoderm-derived cells in liver development

The liver is an indispensable organ for metabolism and drug detoxification. The liver consists of endoderm-derived hepatobiliary lineages and various mesoderm-derived cells, and interacts with the surrounding tissues and organs through the ventral mesentery. Liver development, from hepatic specification to liver maturation, requires close interactions with mesoderm-derived cells, such as mesothelial cells, hepatic stellate cells, mesenchymal cells, liver sinusoidal endothelial cells and hematopoietic cells. These cells affect liver development through precise signaling events and even direct physical contact. Through the use of new techniques, emerging studies have recently led to a deeper understanding of liver development and its related mechanisms, especially the roles of mesodermal cells in liver development. Based on these developments, the current protocols for in vitro hepatocyte-like cell induction and liver-like tissue construction have been optimized and are of great importance for the treatment of liver diseases. Here, we review the roles of mesoderm-derived cells in the processes of liver development, hepatocyte-like cell induction and liver-like tissue construction.

Comparative Analysis of Regulatory Role of Notch Signaling Pathway in 8 Types Liver Cell During Liver Regeneration

Notch signaling is closely related to cell proliferation, cell apoptosis, cell fate decisions, DNA damage repair, and so on. However, the exactly regulatory mechanism of Notch signaling pathway in liver regeneration (LR) remains unclear. To reveal the role of Notch signaling pathway in rat liver regeneration, Ingenuity Pathway Analysis (IPA) software and related pathway database were firstly used to construct the Notch signaling pathway in this study. Next, eight type cells with high purity were obtained by Percoll density centrifugation and immunomagnetic beads sorting. Then, the expression profiles of Notch signaling pathway-related genes in eight type cells were checked by using Rat Genome 230 2.0 Array, and the results showed that the expression of 42 genes were significantly regulated. H-cluster results showed that the hepatic stellate cells are attributed to one cluster; hepatocyte cell, oval cell, sinusoidal endothelial cell, and Kupffer cell are clustered together; and biliary epithelial cell, pit cell, and dendritic cell are one cluster. IPA software and Expression analysis systematic explorer analysis indicated that Notch signaling pathway-related genes were involved in cell proliferation, apoptosis, cell cycle, DNA damage repair, etc. In conclusion, Notch signaling pathway might regulate various physiological activities of LR through multiple pathways.