Gremlin1 Accelerates Hepatic Stellate Cell Activation Through Upregulation of TGF-Beta Expression

The possible role of Gremlin1 in inflammatory apical periodontitis

OBJECTIVE

In this study, we investigated the involvement of Gremlin1 on the pathological process of apical periodontitis and detect the underlying mechanisms preliminarily.

METHODS

Clinical healthy and inflamed periapical specimens were collected. Then, apical periodontitis (AP) animal models were established by consistent pulp exposure. In addition, AAV-shGremlin1 was injected into inflamed periapical lesions to inhibit the expression of Gremlin1. Alveolar bone loss was measured by Micro-CT. Furthermore, immunohistochemical or immunofluorescence staining of Gremlin1, phosphorylated-CREB, ICAM-1, VCAM-1, IL-1β were performed.

RESULTS

The expression of Gremlin1 is markedly increased in periapical lesions not only in clinic samples but also in animal models. Moreover, in rats' AP model, we uncovered that the Gremlin1 protein expression levels in apical lesions is positively correlated with those of IL-1β. Besides, the blockade of Gremlin1 in periapical lesions could substantially suppress the alveolar bone loss and restrains the inflammatory status by impacting the activation levels of phosphorylated-CREB, ICAM-1, VCAM-1, IL-1β.

CONCLUSIONS

Taken together, these results illustrated that Gremlin1 acts as a crucial mediator and possibly serves as a potential diagnostic marker for periapical periodontitis. Discovery of new factors involved in the pathophysiology of periapical periodontitis could contribute to the development of novel therapeutic treatment for the disease.

Gremlin-1 Promotes Colorectal Cancer Cell Metastasis by Activating ATF6 and Inhibiting ATF4 Pathways

Cancer cell survival, function and fate strongly depend on endoplasmic reticulum (ER) proteostasis. Although previous studies have implicated the ER stress signaling network in all stages of cancer development, its role in cancer metastasis remains to be elucidated. In this study, we investigated the role of Gremlin-1 (GREM1), a secreted protein, in the invasion and metastasis of colorectal cancer (CRC) cells in vitro and in vivo. Firstly, public datasets showed a positive correlation between high expression of GREM1 and a poor prognosis for CRC. Secondly, GREM1 enhanced motility and invasion of CRC cells by epithelial–mesenchymal transition (EMT). Thirdly, GREM1 upregulated expression of activating transcription factor 6 (ATF6) and downregulated that of ATF4, and modulation of the two key players of the unfolded protein response (UPR) was possibly through activation of PI3K/AKT/mTOR and antagonization of BMP2 signaling pathways, respectively. Taken together, our results demonstrate that GREM1 is an invasion-promoting factor via regulation of ATF6 and ATF4 expression in CRC cells, suggesting GREM1 may be a potential pharmacological target for colorectal cancer treatment.

Fibrin, Bone Marrow Cells and Macrophages Interactively Modulate Cardiomyoblast Fate

Interactions between macrophages, cardiac cells and the extracellular matrix are crucial for cardiac repair following myocardial infarction (MI). We hypothesized that cell-based treatments might modulate these interactions. After validating that bone marrow cells (BMC) associated with fibrin lowered the infarct extent and improved cardiac function, we interrogated the influence of fibrin, as a biologically active scaffold, on the secretome of BMC and the impact of their association on macrophage fate and cardiomyoblast proliferation. In vitro, BMC were primed with fibrin (F-BMC). RT-PCR and proteomic analyses showed that fibrin profoundly influenced the gene expression and the secretome of BMCs. Consequently, the secretome of F-BMC increased the spreading of cardiomyoblasts and showed an alleviated immunomodulatory capacity. Indeed, the proliferation of anti-inflammatory macrophages was augmented, and the phenotype of pro-inflammatory switched as shown by downregulated Nos2, Il6 and IL1b and upregulated Arg1, CD163, Tgfb and IL10. Interestingly, the secretome of F-BMC educated-macrophages stimulated the incorporation of EdU in cardiomyoblasts. In conclusion, our study provides evidence that BMC/fibrin-based treatment improved cardiac structure and function following MI. In vitro proofs-of-concept reveal that the F-BMC secretome increases cardiac cell size and promotes an anti-inflammatory response. Thenceforward, the F-BMC educated macrophages sequentially stimulated cardiac cell proliferation.

The miR-23b/27b/24-1 Cluster Inhibits Hepatic Fibrosis by Inactivating Hepatic Stellate Cells

BACKGROUND & AIMS

Hepatic fibrosis is characterized by hepatic stellate cell (HSC) activation and transdifferentiation-mediated extracellular matrix (ECM) deposition, which both contribute to cirrhosis. However, no antifibrotic regimen is available in the clinic. microRNA-23b/27b/24-1 cluster inhibition of transforming growth factor-β (TGF-β) signaling during hepatic development prompted us to explore whether this cluster inhibits HSC activation and hepatic fibrosis.

METHODS

Experimental fibrosis was studied in carbon tetrachloride (CCl₄)-treated C57BL/6 mice. After administration of miR-23b/27b/24-1 lentivirus or vehicle, animals were euthanized for liver histology. In primary rat HSC and HSC-T6, the anti-fibrotic effect of miR-23b/27b/24-1 cluster was furtherly investigated by RNA-sequencing, luciferase reporter assay, western blotting and bioinformatic means.

RESULTS

In this study, we showed that increasing the miR-23b/27b/24-1 level through intravenous delivery of miR-23b/27b/24-1 lentivirus ameliorated mouse hepatic fibrosis. Mechanistically, the miR-23b/27b/24-1 cluster directly targeted messenger RNAs, which reduced the protein expression of 5 secretory profibrotic genes (TGF-β2, Gremlin1, LOX, Itgα2, and Itgα5) in HSCs. Suppression of the TGF-β signaling pathway by down-regulation of TGF-β2, Itgα2, and Itgα5, and activation of the bone morphogenetic protein signaling pathway by inhibition of Gremlin1, decreased extracellular matrix secretion of HSCs. Furthermore, down-regulation of LOX expression softened the ECM. Moreover, a reduction in tissue inhibitors of metalloproteinase 1 expression owing to weakened TGF-β signaling increased ECM degradation.

CONCLUSIONS

Hepatic overexpression of the miR-23b/27b/24-1 cluster blocked hepatic fibrosis and may be a novel therapeutic regimen for patients with hepatic fibrosis.

Emerging Role of Bone Morphogenetic Protein 4 in Metabolic Disorders

Bone morphogenetic proteins (BMPs) are a group of signaling molecules that belong to the TGF-β superfamily. Initially discovered for their ability to induce bone formation, BMPs are known to play a diverse and critical array of biological roles. We here focus on recent evidence showing that BMP4 is an important regulator of white/beige adipogenic differentiation with important consequences for thermogenesis, energy homeostasis, and development of obesity in vivo. BMP4 is highly expressed in, and released by, human adipose tissue, and serum levels are increased in obesity. Recent studies have now shown BMP4 to play an important role not only for white/beige/brown adipocyte differentiation and thermogenesis but also in regulating systemic glucose homeostasis and insulin sensitivity. It also has important suppressive effects on hepatic glucose production and lipid metabolism. Cellular BMP4 signaling/action is regulated by both ambient cell/systemic levels and several endogenous and systemic BMP antagonists. Reduced BMP4 signaling/action can contribute to the development of obesity, insulin resistance, and associated metabolic disorders. In this article, we summarize the pleiotropic functions of BMP4 in the pathophysiology of these diseases and also consider the therapeutic implications of targeting BMP4 in the prevention/treatment of obesity and its associated complications.

Down-regulation of Gremlin1 inhibits inflammatory response and vascular permeability in chronic idiopathic urticaria through suppression of TGF-β signaling pathway

Chronic idiopathic urticaria (CIU) is an unfavorable skin condition which could be maintained for six weeks or longer time. Gremlin1 (GREM1) was recently applied in treatments of many diseases. However, the possible regulatory mechanism of GREM1 in CIU remained unclear. This study aimed to explore the regulatory effects of GREM1 on the inflammatory response and vascular permeability mediated by mast cells of CIU via TGF-β signaling pathway. Initially, microarray analysis was used to identify CIU-related differentially expressed genes and the potential mechanism of this gene. A mouse model of CIU was established. To explore the functional role of GREM1 in CIU, the modeled mice were then injected with GREM1-siRNA, SRI-011381 (the activator of TGF-β signaling pathway), or both, followed by serum test, and immunoglobulin detection. The levels of inflammatory factors and tryptase, β-hexosaminase, histamine in the serum were detected. Besides, vascular endothelial cell permeability and the target relation between GREM1 and TGF-β were also examined. Mice injected with SRI-011381 exhibited higher levels of tryptase, β-hexosaminase, histamine, inflammation-related factors and increased vascular endothelial cell permeability, while GREM1-silenced mice yet expressed opposite tendency. Silencing of GREM1 was demonstrated to inhibit the TGF-β signaling pathway. Taken together, our results demonstrated that down-regulation of GREM1 could potentially impede inflammatory response and vascular permeability by suppressing TGF-β signaling pathway. GREM1 may promote the development of prognosis management and therapeutic treatment in CIU.

TGF-β in Hepatic Stellate Cell Activation and Liver Fibrogenesis-Updated 2019

Liver fibrosis is an advanced liver disease condition, which could progress to cirrhosis and hepatocellular carcinoma. To date, there is no direct approved antifibrotic therapy, and current treatment is mainly the removal of the causative factor. Transforming growth factor (TGF)-β is a master profibrogenic cytokine and a promising target to treat fibrosis. However, TGF-β has broad biological functions and its inhibition induces non-desirable side effects, which override therapeutic benefits. Therefore, understanding the pleiotropic effects of TGF-β and its upstream and downstream regulatory mechanisms will help to design better TGF-β based therapeutics. Here, we summarize recent discoveries and milestones on the TGF-β signaling pathway related to liver fibrosis and hepatic stellate cell (HSC) activation, emphasizing research of the last five years. This comprises impact of TGF-β on liver fibrogenesis related biological processes, such as senescence, metabolism, reactive oxygen species generation, epigenetics, circadian rhythm, epithelial mesenchymal transition, and endothelial-mesenchymal transition. We also describe the influence of the microenvironment on the response of HSC to TGF-β. Finally, we discuss new approaches to target the TGF-β pathway, name current clinical trials, and explain promises and drawbacks that deserve to be adequately addressed.

Overexpression of mircoRNA-137 inhibits cervical cancer cell invasion, migration and epithelial-mesenchymal transition by suppressing the TGF-β/smad pathway via binding to GREM1

Background

Accumulating evidence has highlighted the tumor suppressive roles of microRNA (miRNAs) in cervical cancer (CC). In the present study, we aim to delineate the functional relevance of microRNA-137 (miR-137) in influencing epithelial-mesenchymal transition (EMT), and other CC cell biological activities via the TGF-β/smad pathway by binding to GREM1.

Methods

Microarray analysis was initially adopted to predict the differentially expressed genes and the miRNAs related to CC, followed by the measurement of the expression patterns of GREM1, EMT-related factors in the CC tissues and the adjacent tissues. Dual luciferase reporter gene assay was conducted to determine the relationship between miR-137 and GREM1. Gain-of- and loss-of-function experiments were conducted to characterize the effects of miR-137 and GREM1 on the colony formation, proliferation, apoptosis, migration, and invasion of CC cells in vitro, and the tumorigenicity of the CC cells in nude mice. The TGF-β/smad pathway was subsequently blocked with si-TGF-β to investigate its involvement.

Results

Reduced miR-137 expression and increased GREM1 expression were predicted in CC, which was subsequently observed in the CC tissues and cells. Notably, GREM1 was a target gene of miR-137. The overexpressed miR-137 was found to inhibit EMT, cell proliferation, colony formation, invasion, migration and tumorigenesis in nude mice. In addition, miR-137 was noted to inhibit the activation of the TGF-β/smad pathway by binding to GREM1. The silencing of TGF-β1 was shown to reverse the effects induced by downregulated expression of miR-137.

Conclusions

This study suggests that upregulated miR-137 suppresses the tumor progression in CC via blocking the TGF-β/smad pathway by binding to and negatively regulating GREM1.

MiR-542-3p controls hepatic stellate cell activation and fibrosis via targeting BMP-7

There has been an increasing number of studies about microRNAs as key regulators in the development of hepatic fibrosis. Here, we demonstrate that miR-542-3p can promote hepatic fibrosis by downregulating the expression of bone morphogenetic protein 7 (BMP-7), which is known to antagonize transforming growth factor β1 (TGFβ1)-mediated fibrogenesis effect. The expression of miR-542-3p is increased in activated hepatic stellate cells (HSCs). Downregulation of MiR-542-3p by antisense inhibitors can inhibit HSCs activation markers, including α-smooth muscle actin (α-SMA) and collagen as well as TGFβ signaling pathways. MiR-542-3p was significantly upregulated in carbon tetrachloride (CCl₄ )-induced hepatic fibrosis in mice, and downregulation of miR-542-3p by lentivirus could prevent the development of hepatic fibrosis. In addition, miR-542-3p can directly bind to the 3'-untranslated region of BMP-7 mRNA, indicating that its profibrotic effect appears to be caused by its inhibition of BMP-7. Our results suggest that downregulation of miR-542-3p prevents liver fibrosis both in vitro and in vivo, highlighting its potential as a novel biomarker or therapeutic target for hepatic fibrosis.

BMP Signalling at the Crossroad of Liver Fibrosis and Regeneration

Bone Morphogenetic Proteins (BMPs) belong to the Transforming Growth Factor-β (TGF-β) family. Initially identified due to their ability to induce bone formation, they are now known to have multiple functions in a variety of tissues, being critical not only during development for tissue morphogenesis and organogenesis but also during adult tissue homeostasis. This review focus on the liver as a target tissue for BMPs actions, devoting most efforts to summarize our knowledge on their recently recognized and/or emerging roles on regulation of the liver regenerative response to various insults, either acute or chronic and their effects on development and progression of liver fibrosis in different pathological conditions. In an attempt to provide the basis for guiding research efforts in this field both the more solid and more controversial areas of research were highlighted.