Rho/Rock cross-talks with transforming growth factor-β/Smad pathway participates in lung fibroblast-myofibroblast differentiation

An inducible sphingosine kinase 1 in hepatic stellate cells potentiates liver fibrosis

Hepatic stellate cells (HSCs) play a role in hepatic fibrosis and sphingosine kinase (SphK) is involved in biological processes. As studies on the regulatory mechanisms and functions of SphK in HSCs during liver fibrosis are currently limited, this study aimed to elucidate the regulatory mechanism and connected pathways of SphK upon HSC activation. The expression of SphK1 was higher in HSCs than in hepatocytes, and upregulated in activated primary HSCs. SphK1 was also increased in liver homogenates of carbon tetrachloride-treated or bile duct ligated mice and in transforming growth factor-β (TGF-β)-treated LX-2 cells. TGF-β-mediated SphK1 induction was due to Smad3 signaling in LX-2 cells. SphK1 modulation altered the expression of liver fibrogenesis-related genes. This SphK1-mediated profibrogenic effect was dependent on SphK1/sphingosine-1-phosphate/sphingosine-1-phosphate receptor signaling through ERK. EGCG blocked TGF-β-induced SphK1 expression and hepatic fibrogenesis by attenuating Smad and MAPK activation. SphK1 induced by TGF-β facilitates HSC activation and liver fibrogenesis, which is reversed by EGCG. Accordingly, SphK1 and related signal transduction may be utilized to treat liver fibrosis.

Electroacupuncture improves retinal function in myopia Guinea pigs probably via inhibition of the RhoA/ROCK2 signaling pathway

Objective

To investigate the effect of electroacupuncture (EA) on retinal function in guinea pigs with negative lens-induced myopia (LIM) by inhibiting the RhoA/ROCK2 signaling pathway.

Methods

Guinea pigs were randomly divided into normal control (NC) group, LIM group, EA group, SHAM acupoint (SHAM) group, and electro-acupuncture + ROCK pathway inhibitor Y27632 (EA + Y27632) group. The refraction, axial length, retinal blood flow density, choroidal vascular index, retinal physiological function, the contents of total antioxidant capacity (T-AOC), catalase (CAT), glutathione (GSH), superoxide dismutase (SOD) and malondialdehyde (MDA) of each group were determined. The changes in retinal tissue structure were observed by hematoxylin and eosin (H&E) staining, and the expression of the RhoA/ROCK2 signaling pathway-related molecules in the retina was measured by real-time quantitative polymerase chain reaction (qPCR) and Western blot.

Results

Myopic refraction, AL, and MDA content in the LIM and SHAM groups were significantly increased, retinal blood flow density and CVI, SOD, GSH, CAT, T-AOC content were decreased. After EA intervention, myopic refraction, AL, and MDA content decreased, retinal blood flow density and CVI, SOD, GSH, CAT, T-AOC content were increased. H&E staining showed that the thickness of the guinea pig retina, the thickness of the inner and outer layers of the nucleus, and the number of cells were significantly increased after EA intervention. qPCR and western blot analyses showed that the expression of RhoA、ROCK2、MLC、CollagenⅠ、MMP-2、TIMP-2 and α-SMA were elevated in the LIM and SHAM group than those in the NC group. Compared with the LIM group, the expression of EA group was significantly decreased.

Conclusions

Electroacupuncture can improve retinal function by improving retinal blood flow, reducing retinal oxidative damage, inhibiting RhoA/ROCK2 signaling pathway and controlling extracellular matrix remodeling, thus delaying the occurrence and development of myopia.

The role of fibrosis in endometriosis: a systematic review

BACKGROUND

Fibrosis is an important pathological feature of endometriotic lesions of all subtypes. Fibrosis is present in and around endometriotic lesions, and a central role in its development is played by myofibroblasts, which are cells derived mainly after epithelial-to-mesenchymal transition (EMT) and fibroblast-to-myofibroblast transdifferentiation (FMT). Transforming growth factor-β (TGF-β) has a key role in this myofibroblastic differentiation. Myofibroblasts deposit extracellular matrix (ECM) and have contracting abilities, leading to a stiff micro-environment. These aspects are hypothesized to be involved in the origin of endometriosis-associated pain. Additionally, similarities between endometriosis-related fibrosis and other fibrotic diseases, such as systemic sclerosis or lung fibrosis, indicate that targeting fibrosis could be a potential therapeutic strategy for non-hormonal therapy for endometriosis.

OBJECTIVE AND RATIONALE

This review aims to summarize the current knowledge and to highlight the knowledge gaps about the role of fibrosis in endometriosis. A comprehensive literature overview about the role of fibrosis in endometriosis can improve the efficiency of fibrosis-oriented research in endometriosis.

SEARCH METHODS

A systematic literature search was performed in three biomedical databases using search terms for 'endometriosis', 'fibrosis', 'myofibroblasts', 'collagen', and 'α-smooth muscle actin'. Original studies were included if they reported about fibrosis and endometriosis. Both preclinical in vitro and animal studies, as well as research concerning human subjects were included.

OUTCOMES

Our search yielded 3441 results, of which 142 studies were included in this review. Most studies scored a high to moderate risk of bias according to the bias assessment tools. The studies were divided in three categories: human observational studies, experimental studies with human-derived material, and animal studies. The observational studies showed details about the histologic appearance of fibrosis in endometriosis and the co-occurrence of nerves and immune cells in lesions. The in vitro studies identified several pro-fibrotic pathways in relation to endometriosis. The animal studies mainly assessed the effect of potential therapeutic strategies to halt or regress fibrosis, for example targeting platelets or mast cells.

WIDER IMPLICATIONS

This review shows the central role of fibrosis and its main cellular driver, the myofibroblast, in endometriosis. Platelets and TGF-β have a pivotal role in pro-fibrotic signaling. The presence of nerves and neuropeptides is closely associated with fibrosis in endometriotic lesions, and is likely a cause of endometriosis-associated pain. The process of fibrotic development after EMT and FMT shares characteristics with other fibrotic diseases, so exploring similarities in endometriosis with known processes in diseases like systemic sclerosis, idiopathic pulmonary fibrosis or liver cirrhosis is relevant and a promising direction to explore new treatment strategies. The close relationship with nerves appears rather unique for endometriosis-related fibrosis and is not observed in other fibrotic diseases.

REGISTRATION NUMBER

N/A.

MAPK Phosphatase-5 is required for TGF-β signaling through a JNK-dependent pathway

Mitogen-activated protein kinase (MAPK) phosphatases (MKPs) constitute members of the dual-specificity family of protein phosphatases that dephosphorylate the MAPKs. MKP-5 dephosphorylates the stress-responsive MAPKs, p38 MAPK and JNK, and has been shown to promote tissue fibrosis. Here, we provide insight into how MKP-5 regulates the transforming growth factor-β (TGF-β) pathway, a well-established driver of fibrosis. We show that MKP-5-deficient fibroblasts in response to TGF-β are impaired in SMAD2 phosphorylation at canonical and non-canonical sites, nuclear translocation, and transcriptional activation of fibrogenic genes. Consistent with this, pharmacological inhibition of MKP-5 is sufficient to block TGF-β signaling, and that this regulation occurs through a JNK-dependent pathway. By utilizing RNA sequencing and transcriptomic analysis, we identify TGF-β signaling activators regulated by MKP-5 in a JNK-dependent manner, providing mechanistic insight into how MKP-5 promotes TGF-β signaling. This study elucidates a novel mechanism whereby MKP-5-mediated JNK inactivation is required for TGF-β signaling and provides insight into the role of MKP-5 in fibrosis.

Modeling epithelial homeostasis and perturbation in three-dimensional human esophageal organoids

Background

Esophageal organoids from a variety of pathologies including cancer are grown in Advanced Dulbecco's Modified Eagle Medium-Nutrient Mixture F12 (hereafter ADF). However, the currently available ADF-based formulations are suboptimal for normal human esophageal organoids, limiting the ability to compare normal esophageal organoids with those representing a given disease state.

Methods

We have utilized immortalized normal human esophageal epithelial cell (keratinocyte) lines EPC1 and EPC2 and endoscopic normal esophageal biopsies to generate three-dimensional (3D) organoids. To optimize ADF-based medium, we evaluated the requirement of exogenous epidermal growth factor (EGF) and inhibition of transforming growth factor-(TGF)-β receptor-mediated signaling, both key regulators of proliferation of human esophageal keratinocytes. We have modeled human esophageal epithelial pathology by stimulating esophageal 3D organoids with interleukin (IL)-13, an inflammatory cytokine, or UAB30, a novel pharmacological activator of retinoic acid signaling.

Results

The formation of normal human esophageal 3D organoids was limited by excessive EGF and intrinsic TGFβ receptor-mediated signaling. In optimized HOME0, normal human esophageal organoid formation was improved, whereas IL-13 and UAB30 induced epithelial changes reminiscent of basal cell hyperplasia, a common histopathologic feature in broad esophageal disease conditions including eosinophilic esophagitis. Conclusions: HOME0 allows modeling of the homeostatic differentiation gradient and perturbation of the human esophageal epithelium while permitting a comparison of organoids from mice and other organs grown in ADF-based media.

Differential Smad2/3 linker phosphorylation is a crosstalk mechanism of Rho/ROCK and canonical TGF-β3 signaling in tenogenic differentiation

The transforming growth factor (TGF)-β3 is a well-known inducer for tenogenic differentiation, signaling via the Smad2/3 pathway. Furthermore, other factors like extracellular matrix or mechanical force can induce tenogenic differentiation and possibly alter the response to TGF-β3 by signaling via the Rho/ROCK pathway. The aim of this study was to investigate the interplay of Rho/ROCK and TGF-β3/Smad signaling in tenogenic differentiation, with the Smad2/3 molecule hypothesized as a possible interface. Cultured as monolayers or on collagen I matrices, mesenchymal stromal cells (MSC) were treated with the ROCK inhibitor Y-27632 (10 µM), TGF-β3 (10 ng/ml) or both combined. Control cells were cultured accordingly, without Y-27632 and/or without TGF-β3. At different time points, MSC were analyzed by real-time RT-PCR, immunofluorescence, and Western blot. Cultivation of MSC on collagen matrices and ROCK inhibition supported tenogenic differentiation and fostered the effect of TGF-β3. The phosphorylation of the linker region of Smad2 was reduced by cultivation on collagen matrices, but not by ROCK inhibition. The latter, however, led to increased phosphorylation of the linker region of Smad3. In conclusion, collagen matrices and the Rho/ROCK signaling pathway influence the TGF-β3/Smad2/3 pathway by regulating different phosphorylation sites of the Smad linker region.

Unraveling the interplay between vital organelle stress and oxidative stress in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease characterized by excessive accumulation of extracellular matrix, leading to irreversible fibrosis. Emerging evidence suggests that endoplasmic reticulum (ER) stress, mitochondrial stress, and oxidative stress pathways play crucial roles in the pathogenesis of IPF. ER stress occurs when the protein folding capacity of the ER is overwhelmed, triggering the unfolded protein response (UPR) and contributing to protein misfolding and cellular stress in IPF. Concurrently, mitochondrial dysfunction involving dysregulation of key regulators, including PTEN-induced putative kinase 1 (PINK1), Parkin, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), and sirtuin 3 (SIRT3), disrupts mitochondrial homeostasis and impairs cellular energy metabolism. This leads to increased reactive oxygen species (ROS) production, release of pro-fibrotic mediators, and activation of fibrotic pathways, exacerbating IPF progression. The UPR-induced ER stress further disrupts mitochondrial metabolism, resulting in altered mitochondrial mechanisms that increase the generation of ROS, resulting in further ER stress, creating a feedback loop that contributes to the progression of IPF. Oxidative stress also plays a pivotal role in IPF, as ROS-mediated activation of TGF-β, NF-κB, and MAPK pathways promotes inflammation and fibrotic responses. This review mainly focuses on the links between ER stress, mitochondrial dysfunctions, and oxidative stress with different signaling pathways involved in IPF. Understanding these mechanisms and targeting key molecules within these pathways may offer promising avenues for intervention.

Regulation of Corneal Stromal Cell Behavior by Modulating Curvature Using a Hydraulically Controlled Organ Chip Array

Curvature is a critical factor in cornea mechanobiology, but its impact on phenotypic alterations and extracellular matrix remodeling of cornea stroma remains unclear. In this work, we investigated how curvature influences the corneal stroma using a hydraulically controlled curvature array chip. The responses of stromal cells to low, medium, and high curvatures were observed by preparing three phenotypes of corneal stromal cells: corneal keratocytes, fibroblasts, and myofibroblasts. Keratocytes exhibited phenotypic alterations in response to curvature changes, notably including a decrease in ALDH3 expression and an increase in α-SMA expression. For focal adhesion, corneal fibroblast and myofibroblasts showed enhanced vinculin localization in response to curvature, while corneal keratocytes presented reduced vinculin expression. For cell alignment and ECM expression, most stromal cells under all curvatures showed a radially organized f-actin and collagen fibrils. Interestingly, for corneal fibroblast under medium curvature, we observed orthogonal cell alignment, which is linked to the unique hoop and meridional stress profiles of the curved surface. Furthermore, lumican expression was upregulated in corneal keratocytes, and keratocan expression was increased in corneal fibroblasts and myofibroblasts due to curvature. These results demonstrate that curvature influences both the phenotype of corneal stromal cells and the structural organization of corneal stroma tissue without any external stimuli. This curvature-dependent behavior of corneal stromal cells presents potential opportunities for creating therapeutic strategies for corneal shape dysfunctions.

MARCH8 downregulation modulates profibrotic responses including myofibroblast differentiation

Interstitial lung diseases can result in poor patient outcomes, especially in idiopathic pulmonary fibrosis (IPF), a severe interstitial lung disease with unknown causes. The lack of treatment options requires further understanding of the pathological process/mediators. Membrane-associated RING-CH 8 (MARCH8) has been implicated in immune function regulation and inflammation, however, its role in the development of pulmonary fibrosis and particularly the fibroblast to myofibroblast transition (FMT) remains a gap in existing knowledge. In this study, we demonstrated decreased MARCH8 expression in patients with IPF compared with non-PF controls and in bleomycin-induced PF. TGF-β dose- and time-dependently decreased MARCH8 expression in normal and IPF human lung fibroblast (HLFs), along with induction of FMT markers α-SMA, collagen type I (Col-1), and fibronectin (FN). Interestingly, overexpression of MARCH8 significantly suppressed TGF-β-induced expression of α-SMA, Col-1, and FN. By contrast, the knockdown of MARCH8 using siRNA upregulated basal expression of α-SMA/Col-1/FN. Moreover, MARCH8 knockdown enhanced TGF-β-induced FMT marker expression. These data clearly show that MARCH8 is a critical "brake" for FMT and potentially affects PF. We further found that TGF-β suppressed MARCH8 mRNA expression and the proteasome inhibitor MG132 failed to block MARCH8 decrease induced by TGF-β. Conversely, TGF-β decreases mRNA levels of MARCH8 in a dose- and time-dependent manner, suggesting the transcriptional regulation of MARCH8 by TGF-β. Mechanistically, MARCH8 overexpression suppressed TGF-β-induced Smad2/3 phosphorylation, which may account for the observed effects. Taken together, this study demonstrated an unrecognized role of MARCH8 in negatively regulating FMT and profibrogenic responses relevant to interstitial lung diseases.NEW & NOTEWORTHY MARCH8 is an important modulator of inflammation, immunity, and other cellular processes. We found that MARCH8 expression is downregulated in the lungs of patients with idiopathic pulmonary fibrosis (IPF) and experimental models of pulmonary fibrosis. Furthermore, TGF-β1 decreases MARCH8 transcriptionally in human lung fibroblasts (HLFs). MARCH8 overexpression blunts TGF-β1-induced fibroblast to myofibroblast transition while knockdown of MARCH8 drives this profibrotic change in HLFs. The findings support further exploration of MARCH8 as a novel target in IPF.

Influence of Rho/ROCK inhibitor Y-27632 on proliferation of equine mesenchymal stromal cells

Mesenchymal stromal cells (MSC) isolated form bone marrow and adipose tissue are the most common cells used for cell therapy of orthopedic diseases. MSC derived from different tissues show differences in terms of their proliferation, differentiation potential and viability in prolonged cell culture. This suggests that there may be subtle differences in intracellular signaling pathways that modulate these cellular characteristics. The Rho/ROCK signaling pathway is essential for many cellular functions. Targeting of this pathway by the ROCK inhibitor Y-27632 has been shown to be beneficial for cell viability and proliferation of different cell types. The aim of this study was to investigate the effects of Rho/ROCK inhibition on equine MSC proliferation using bone marrow-derived MSC (BMSC) and adipose-derived MSC (ASC). Primary ASC and BMSC were stimulated with or without 10 ng/mL TGF-β3 or 10 μM Y-27632, as well as both in combination. Etoposide at 10 μM was used as a positive control for inhibition of cell proliferation. After 48 h of stimulation, cell morphology, proliferation activity and gene expression of cell senescence markers p53 and p21 were assessed. ASC showed a trend for higher basal proliferation than BMSC, which was sustained following stimulation with TGF-β3. This included a higher proliferation with TGF-β3 stimulation compared to Y-27632 stimulation (p < 0.01), but not significantly different to the no treatment control when used in combination. Expression of p21 and p53 was not altered by stimulation with TGF-β3 and/or Y-27632 in either cell type. In summary, the Rho/ROCK inhibitor Y-27632 had no effect on proliferation activity and did not induce cell senescence in equine ASC and BMSC.

TIMP-1 and its potential diagnostic and prognostic value in pulmonary diseases

Tissue inhibitors of metalloproteases (TIMPs) have caught the attention of many scientists due to their role in various physiological and pathological processes. TIMP-1, 2, 3, and 4 are known members of the TIMPs family. TIMPs exert their biological effects by, but are not limited to, inhibiting the activity of metalloproteases (MMPs). The balance between MMPs and TIMPs is critical for maintaining homeostasis of the extracellular matrix (ECM), while the imbalance between MMPs and TIMPs can lead to pathological changes, such as cancer. In this review, we summarized the current knowledge of TIMP-1 in several pulmonary diseases namely, acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), pneumonia, asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis, and pulmonary fibrosis. Considering the potential of TIMP-1 serving as a non-invasive diagnostic and/or prognostic biomarker, we also reviewed the circulating TIMP-1 levels in translational and clinical studies.

Application and Study of ROCK Inhibitors in Pulmonary Fibrosis: Recent Developments and Future Perspectives

Rho-associated coiled-coil-containing kinases (ROCKs), serine/threonine protein kinases, were initially identified as downstream targets of the small GTP-binding protein Rho. Pulmonary fibrosis (PF) is a lethal disease with limited therapeutic options and a particularly poor prognosis. Interestingly, ROCK activation has been demonstrated in PF patients and in animal PF models, making it a promising target for PF treatment. Many ROCK inhibitors have been discovered, and four of these have been approved for clinical use; however, no ROCK inhibitors are approved for the treatment of PF patients. In this article, we describe ROCK signaling pathways and the structure-activity relationship, potency, selectivity, binding modes, pharmacokinetics (PKs), biological functions, and recently reported inhibitors of ROCKs in the context of PF. We will also focus our attention on the challenges to be addressed when targeting ROCKs and discuss the strategy of ROCK inhibitor use in the treatment of PF.

Embryonic organizer formation disorder leads to multiorgan dysplasia in Down syndrome

Despite the high prevalence of Down syndrome (DS) and early identification of the cause (trisomy 21), its molecular pathogenesis has been poorly understood and specific treatments have consequently been practically unavailable. A number of medical conditions throughout the body associated with DS have prompted us to investigate its molecular etiology from the viewpoint of the embryonic organizer, which can steer the development of surrounding cells into specific organs and tissues. We established a DS zebrafish model by overexpressing the human DYRK1A gene, a highly haploinsufficient gene located at the "critical region" within 21q22. We found that both embryonic organizer and body axis were significantly impaired during early embryogenesis, producing abnormalities of the nervous, heart, visceral, and blood systems, similar to those observed with DS. Quantitative phosphoproteome analysis and related assays demonstrated that the DYRK1A-overexpressed zebrafish embryos had anomalous phosphorylation of β-catenin and Hsp90ab1, resulting in Wnt signaling enhancement and TGF-β inhibition. We found an uncovered ectopic molecular mechanism present in amniocytes from fetuses diagnosed with DS and isolated hematopoietic stem cells (HSCs) of DS patients. Importantly, the abnormal proliferation of DS HSCs could be recovered by switching the balance between Wnt and TGF-β signaling in vitro. Our findings provide a novel molecular pathogenic mechanism in which ectopic Wnt and TGF-β lead to DS physical dysplasia, suggesting potential targeted therapies for DS.

Graphene Hydrogel as a Porous Scaffold for Cartilage Regeneration

Porous scaffolds have widely been exploited in cartilage tissue regeneration. However, it is often difficult to understand how the delicate hierarchical structure of the scaffold material affects the regeneration process. Graphene materials are versatile building blocks for robust and biocompatible porous structures, enabling investigation of structural cues on tissue regeneration otherwise challenging to ascertain. Here, we utilize a graphene hydrogel with stable and tunable structure as a model scaffold to examine the effect of porous structure on matrix remodeling associated with ingrowth of chondrocytes on scaffolds. We observe much-accelerated yet balanced cartilage remodeling correlating the ingrowth of chondrocytes into the graphene scaffold with an open pore structure on the surface. Importantly, such an enhanced remodeling selectively promotes the expression of collagen type II fibrils over proteoglycan aggrecan, hence clearly illustrating that chondrocytes maintain a stable phenotype when they migrate into the scaffold while offering new insights into scaffold design for cartilage repair.

The Novel Small Molecule BTB Inhibits Pro-Fibrotic Fibroblast Behavior though Inhibition of RhoA Activity

Idiopathic pulmonary fibrosis (IPF) is a progressive, chronic, interstitial lung disease with a poor prognosis. Although specific anti-fibrotic medications are now available, the median survival time following diagnosis remains very low, and new therapies are urgently needed. To uncover novel therapeutic targets, we examined how biochemical properties of the fibrotic lung are different from the healthy lung. Previous work identified lactate as a metabolite that is upregulated in IPF lung tissue. Importantly, inhibition of the enzyme responsible for lactate production prevents fibrosis in vivo. Further studies revealed that fibrotic lesions of the lung experience a significant decline in tissue pH, likely due to the overproduction of lactate. It is not entirely clear how cells in the lung respond to changes in extracellular pH, but a family of proton sensing G-protein coupled receptors has been shown to be activated by reductions in extracellular pH. This work examines the expression profiles of proton sensing GPCRs in non-fibrotic and IPF-derived primary human lung fibroblasts. We identify TDAG8 as a proton sensing GPCR that is upregulated in IPF fibroblasts and that knockdown of TDAG8 dampens myofibroblast differentiation. To our surprise, BTB, a proposed positive allosteric modulator of TDAG8, inhibits myofibroblast differentiation. Our data suggest that BTB does not require TDAG8 to inhibit myofibroblast differentiation, but rather inhibits myofibroblast differentiation through suppression of RhoA mediated signaling. Our work highlights the therapeutic potential of BTB as an anti-fibrotic treatment and expands upon the importance of RhoA-mediated signaling pathways in the context of myofibroblast differentiation. Furthermore, this works also suggests that TDAG8 inhibition may have therapeutic relevance in the treatment of IPF.

NHLRC2 expression is increased in idiopathic pulmonary fibrosis

BACKGROUND

Variants of NHL repeat-containing protein 2 (NHLRC2) have been associated with severe fibrotic interstitial lung disease in early childhood and NHLRC2 has been listed as a differentially expressed gene between rapidly and slowly progressing idiopathic pulmonary fibrosis (IPF) patients. However, its cell type-specific localization in human lung tissue is unknown. The aim of this study was to evaluate NHLRC2 mRNA and protein expression in different cell types of lung tissue samples and to investigate the effect of transforming growth factor (TGF)-β1 exposure on NHLRC2 expression in vitro.

METHODS

The NHLRC2 expression in lung tissue samples was studied by immunohistochemistry (50 IPF, 10 controls) and mRNA in situ hybridization (8 IPF, 3 controls). The immunohistochemical NHLRC2 expression was quantified with image analysis software and associated with the clinical and smoking data of the patients. NHLRC2 expression levels in primary stromal and small airway epithelial cell lines after exposure to TGF-β1 was measured by quantitative reverse transcription polymerase chain reaction and Western blot analysis.

RESULTS

NHLRC2 expression was detected especially in bronchiolar epithelial cells, type II pneumocytes and macrophages in normal lung. In the lungs of IPF patients, NHLRC2 was mainly expressed in hyperplastic alveolar epithelial cells lining fibroblast foci and honeycombs. NHLRC2 expression assessed by image analysis was higher in IPF compared to controls (p < 0.001). Ever-smokers had more prominent NHLRC2 staining than non-smokers (p = 0.037) among IPF patients. TGF-β1 exposure did not influence NHLRC2 levels in lung cell lines.

CONCLUSIONS

NHLRC2 expression was higher in IPF compared to controls being widely expressed in type II pneumocytes, macrophages, bronchiolar epithelium, and hyperplastic alveolar epithelium. Additionally, its expression was not regulated by the exposure to TGF-β1 in vitro. Further studies are needed to clarify the role of NHLRC2 in IPF.

Ferroptosis and its role in cardiomyopathy

Heart disease is the leading cause of death worldwide. Cardiomyopathy is a disease characterized by the heart muscle damage, resulting heart in a structurally and functionally change, as well as heart failure and sudden cardiac death. The key pathogenic factor of cardiomyopathy is the loss of cardiomyocytes, but the related molecular mechanisms remain unclear. Ferroptosis is a newly discovered regulated form of cell death, characterized by iron accumulation and lipid peroxidation during cell death. Recent studies have shown that ferroptosis plays an important regulatory roles in the occurrence and development of many heart diseases such as myocardial ischemia/reperfusion injury, cardiomyopathy and heart failure. However, the systemic association of ferroptosis and cardiomyopathy remains largely unknown and needs to be elucidated. In this review, we provide an overview of the molecular mechanisms of ferroptosis and its role in individual cardiomyopathies, highlight that targeting ferroptosis maybe a potential therapeutic strategy for cardiomyopathy therapy in the future.

Rho-associated, coiled-coil-containing protein kinase 1 regulates development of diabetic kidney disease via modulation of fatty acid metabolism

Dysregulation of fatty acid utilization is increasingly recognized as a significant component of diabetic kidney disease. Rho-associated, coiled-coil-containing protein kinase (ROCK) is activated in the diabetic kidney, and studies over the past decade have illuminated ROCK signaling as an essential pathway in diabetic kidney disease. Here, we confirmed the distinct role of ROCK1, an isoform of ROCK, in fatty acid metabolism using glomerular mesangial cells and ROCK1 knockout mice. Mesangial cells with ROCK1 deletion were protected from mitochondrial dysfunction and redox imbalance driven by transforming growth factor β, a cytokine upregulated in diabetic glomeruli. We found that high-fat diet-induced obese ROCK1 knockout mice exhibited reduced albuminuria and histological abnormalities along with the recovery of impaired fatty acid utilization and mitochondrial fragmentation. Mechanistically, we found that ROCK1 regulates the induction of critical mediators in fatty acid metabolism, including peroxisome proliferator-activated receptor gamma coactivator 1α, carnitine palmitoyltransferase 1, and widespread program-associated cellular metabolism. Thus, our findings highlight ROCK1 as an important regulator of energy homeostasis in mesangial cells in the overall pathogenesis of diabetic kidney disease.

A Quartet Network Analysis Identifying Mechanically Responsive Long Noncoding RNAs in Bone Remodeling

Mechanical force, being so ubiquitous that it is often taken for granted and overlooked, is now gaining the spotlight for reams of evidence corroborating their crucial roles in the living body. The bone, particularly, experiences manifold extraneous force like strain and compression, as well as intrinsic cues like fluid shear stress and physical properties of the microenvironment. Though sparkled in diversified background, long noncoding RNAs (lncRNAs) concerning the mechanotransduction process that bone undergoes are not yet detailed in a systematic way. Our principal goal in this research is to highlight the potential lncRNA-focused mechanical signaling systems which may be adapted by bone-related cells for biophysical environment response. Based on credible lists of force-sensitive mRNAs and miRNAs, we constructed a force-responsive competing endogenous RNA network for lncRNA identification. To elucidate the underlying mechanism, we then illustrated the possible crosstalk between lncRNAs and mRNAs as well as transcriptional factors and mapped lncRNAs to known signaling pathways involved in bone remodeling and mechanotransduction. Last, we developed combinative analysis between predicted and established lncRNAs, constructing a pathway–lncRNA network which suggests interactive relationships and new roles of known factors such as H19. In conclusion, our work provided a systematic quartet network analysis, uncovered candidate force-related lncRNAs, and highlighted both the upstream and downstream processes that are possibly involved. A new mode of bioinformatic analysis integrating sequencing data, literature retrieval, and computational algorithm was also introduced. Hopefully, our work would provide a moment of clarity against the multiplicity and complexity of the lncRNA world confronting mechanical input.

Serine-Threonine Kinase inhibition as antifibrotic therapy: TGF-β and ROCK inhibitors

Serine-threonine kinases mediate the phosphorylation of intracellular protein targets, transferring a phosphorus group from an ATP molecule to the specific amino acid residues within the target proteins. Serine-threonine kinases regulate multiple key cellular functions. From this large group of kinases, transforming growth factor beta (TGF-β) through the serine-threonine activity of its receptors and Rho kinase (ROCK) play an important role in the development and maintenance of fibrosis in various human diseases, including systemic sclerosis. In recent years, multiple drugs targeting and inhibiting these kinases, have been developed, opening the possibility of becoming potential antifibrotic agents of clinical value for treating fibrotic diseases. This review analyzes the contribution of TGF- β and ROCK-mediated serine-threonine kinase molecular pathways to the development and maintenance of pathological fibrosis and the potential clinical use of their inhibition.

Rho/ROCK Inhibition Promotes TGF-β3-Induced Tenogenic Differentiation in Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSC) represent a promising therapeutic tool for tendon regeneration. Their tenogenic differentiation is crucial for tissue engineering approaches and may support their beneficial effects after cell transplantation in vivo. The transforming growth factor (TGF)-β, signalling via intracellular Smad molecules, is a potent paracrine mediator of tenogenic induction. Moreover, scaffold topography or tendon matrix components induced tenogenesis via activation of the Rho/ROCK cascade, which, however, is also involved in pathological adaptations in extracellular matrix pathologies. The aim of this study was to investigate the interplay of Rho/ROCK and TGF-β3/Smad signalling in tenogenic differentiation in both human and equine MSC. Primary equine and human MSC isolated from adipose tissue were cultured as monolayers or on tendon-derived decellularized scaffolds to evaluate the influence of the ROCK inhibitor Y-27632 on TGF-β3-induced tenogenic differentiation. The MSC were incubated with and without TGF-β3 (10 ng/ml), Y-27632 (10 μM), or both. On day 1 and day 3, the signalling pathway of TGF-β and the actin cytoskeleton were visualized by Smad 2/3 and phalloidin staining, and gene expression of signalling molecules and tendon markers was assessed. ROCK inhibition was confirmed by disruption of the actin cytoskeleton. Activation of Smad 2/3 with nuclear translocation was evident upon TGF-β3 stimulation. Interestingly, this effect was most pronounced with additional ROCK inhibition in both species (p < 0.05 in equine MSC). In line with that, the tendon marker scleraxis showed the strongest upregulation when TGF-β3 and ROCK inhibition were combined (p < 0.05 in human MSC). The regulation pattern of tendon extracellular matrix components and the signalling molecules TGF-β3 and Smad 8 showed differences between human and equine MSC. The obtained results showed that ROCK inhibition promotes the TGF-β3/Smad 2/3 axis, with possible implications for future MSC priming regimes in tendon therapy.

RhoA/ROCK Signaling Regulates TGF-β1-Induced Fibrotic Effects in Human Pterygium Fibroblasts through MRTF-A

PURPOSE

The overexpression of transforming growth factor-beta1 (TGF-β1) after surgical excision often leads to excessive fibrosis, indicating the recurrence of pterygium. The aims of the present in vitro study were to investigate the role of RhoA/ROCK signaling in regulating fibrotic effects of primary human pterygium fibroblasts (HPFs), as well as to explore the possible mechanisms of these effects.

METHODS

Pterygium samples were obtained from surgery, and profibrotic activation was induced by TGF-β1. Cell proliferation was detected by CCK-8 assay; cell migration was detected by wound healing assay; quantitative real-time PCR and Western blot were used to detect the effects of TGF-β1 and the role of RhoA/ROCK signaling in the synthesis of alpha-smooth muscle actin (a-SMA), type I and III collagen (COL1 and COL3), and matrix metalloproteinase-9 (MMP9) in HPFs. The changes of signaling pathways were detected by Western blot; and pharmaceutical inhibition of RhoA/ROCK signaling and its downstream MRFT-A/SRF transcription pathway were used to assess their possible mechanism in HPFs fibrosis.

RESULTS

ROCK inhibitor Y-27632 decreased TGF-β1-induced cell proliferation and migration, reduced the TGF-β1-induced expression of profibrotic markers in HPFs, and suppressed TGF-β1-induced nuclear accumulation of Myocardin-related transcription factor A (MRTF-A) as well as accompanied elevation of F/G-actin ratio in HPFs. MRTF-A/Serum response factor (SRF) inhibitor CCG-100602 attenuated the TGF-β1-induced α-SMA expression and reduced myofibroblast activation in HPFs.

CONCLUSIONS

RhoA/ROCK signaling played a pivotal role in TGF-β1-induced fibrosis and myofibroblast activation in HPFs at least in part by inactivating the downstream MRTF-A/SRF transcriptional pathway.

MicroRNAs in Transforming Growth Factor-Beta Signaling Pathway Associated With Fibrosis Involving Different Systems of the Human Body

Fibrosis, a major cause of morbidity and mortality, is a histopathological manifestation of many chronic inflammatory diseases affecting different systems of the human body. Two types of transforming growth factor beta (TGF-β) signaling pathways regulate fibrosis: the canonical TGF-β signaling pathway, represented by SMAD-2 and SMAD-3, and the noncanonical pathway, which functions without SMAD-2/3 participation and currently includes TGF-β/mitogen-activated protein kinases, TGF-β/SMAD-1/5, TGF-β/phosphatidylinositol-3-kinase/Akt, TGF-β/Janus kinase/signal transducer and activator of transcription protein-3, and TGF-β/rho-associated coiled-coil containing kinase signaling pathways. MicroRNA (miRNA), a type of non-coding single-stranded small RNA, comprises approximately 22 nucleotides encoded by endogenous genes, which can regulate physiological and pathological processes in fibrotic diseases, particularly affecting organs such as the liver, the kidney, the lungs, and the heart. The aim of this review is to introduce the characteristics of the canonical and non-canonical TGF-β signaling pathways and to classify miRNAs with regulatory effects on these two pathways based on the influenced organ. Further, we aim to summarize the limitations of the current research of the mechanisms of fibrosis, provide insights into possible future research directions, and propose therapeutic options for fibrosis.

P-Rex1 Cooperates With TGFβR2 to Drive Lung Fibroblast Migration in Pulmonary Fibrosis

Pulmonary fibrosis is a kind of interstitial lung disease with progressive pulmonary scar formation, leading to irreversible loss of lung functions. The TGF-β1/Smad signaling pathway plays a key role in fibrogenic processes. It is associated with the increased synthesis of extracellular matrix, enhanced proliferation of fibroblasts, and transformation of alveolar epithelial cells into interstitial cells. We investigated P-Rex1, a PIP₃-Gβγ-dependent guanine nucleotide exchange factor (GEF) for Rac, for its potential role in TGF-β1-induced pulmonary fibrosis. A high expression level of P-Rex1 was identified in the lung tissue of patients with pulmonary fibrosis than that from healthy donors. Using the P-Rex1 knockdown and overexpression system, we established a novel player of P-Rex1 in mouse lung fibroblast migration. P-Rex1 contributed to fibrogenic processes in lung fibroblasts by targeting the TGF-β type Ⅱ receptor (TGFβR2). The RNA-seq analysis for expression profiling confirmed the modulation of P-Rex1 in cell migration and the involvement of P-Rex1 in TGF-β1 signaling. These results identified P-Rex1 as a signaling molecule involved in TGF-β1-induced pulmonary fibrosis, suggesting that P-Rex1 may be a potential target for pulmonary fibrosis treatment.

TGF‑β1: Gentlemanly orchestrator in idiopathic pulmonary fibrosis (Review)

Idiopathic pulmonary fibrosis (IPF) is a worldwide disease characterized by the chronic and irreversible decline of lung function. Currently, there is no drug to successfully treat the disease except for lung transplantation. Numerous studies have been devoted to the study of the fibrotic process of IPF and findings showed that transforming growth factor‑β1 (TGF‑β1) plays a central role in the development of IPF. TGF‑β1 promotes the fibrotic process of IPF through various signaling pathways, including the Smad, MAPK, and ERK signaling pathways. There are intersections between these signaling pathways, which provide new targets for researchers to study new drugs. In addition, TGF‑β1 can affect the fibrosis process of IPF by affecting oxidative stress, epigenetics and other aspects. Most of the processes involved in TGF‑β1 promote IPF, but TGF‑β1 can also inhibit it. This review discusses the role of TGF‑β1 in IPF.

Mechanism of Yifei Decoction Combined with MitoQ on Inhibition of TGFβ1/NOX4 and PDGF/ROCK Signal Pathway in Idiopathic Pulmonary Fibrosis

Background

Rho-related coiled helix forming protein kinase (Rho-ROCK) and another important fibrogenic factor-PDGF play a critical role in collagen deposition in rat lung tissue. Yifei decoction (YFT), a Chinese herbal decoction, has been used to treat idiopathic pulmonary fibrosis (IPF) in clinical practice and has produced positive outcomes; however, convincing evidence is currently lacking. The present study aimed to investigate the effects of YFT combined with MitoQ in rats with IPF and to explore the underlying mechanism.

Methods

Rat IPF model was established by endotracheal injection of 5 mg/kg BleomycinA5 into the specific pathogen-free SD rats. MitoQ (6.5 μmol/kg once daily), YFT (10 ml/kg once daily), and MitoQ + YFT (6.5 μmol/kg + 10 ml/kg once daily) were used to treat the rat model for 4 weeks, respectively. The normal rats without IPF were used as the controls. After 4 weeks of drug treatment, lung histopathology was assessed. Immunohistochemistry was used to detect the expression of fibronectin and collagen IV in lung tissue. The expression of IL-6, IL-1β, TNF-α, GSH-Px, SOD, MDA, and hydroxyproline was determined by enzyme-linked immunosorbent assay. The expressions of TGFβ1, NOX4, PDGFR-β, and ROCK1 were determined using real-time quantitative PCR and Western blot.

Results

After 4 weeks of drug treatment, comparison of the MitoQ + YFT group with the IPF group showed that lung injury scores, W/D, lung tissue hydroxyproline, fibronectin, collagen IV content, and IL-6, IL-1β, TNF-α, and MDA levels were significantly lower (P < 0.05), as well as the expression of TGFβ1, NOX4, PDGFR-β, and ROCK1, but the activity of GSH-Px and SOD was higher (P < 0.05).

Conclusion

MitoQ combined with YFT can improve lung injury in rats with pulmonary fibrosis by reducing the secretion of proinflammatory cytokines and inhibiting TGFβ1/NOX4 and PDGF/ROCK signaling pathways. It may provide a new method for the treatment of pulmonary fibrosis.

The Pathogenesis of Hydrocephalus Following Aneurysmal Subarachnoid Hemorrhage

Hydrocephalus is a common complication of aneurysmal subarachnoid hemorrhage (aSAH) and reportedly contributes to poor neurological outcomes. In this review, we summarize the molecular and cellular mechanisms involved in the pathogenesis of hydrocephalus following aSAH and summarize its treatment strategies. Various mechanisms have been implicated for the development of chronic hydrocephalus following aSAH, including alterations in cerebral spinal fluid (CSF) dynamics, obstruction of the arachnoid granulations by blood products, and adhesions within the ventricular system. Regarding molecular mechanisms that cause chronic hydrocephalus following aSAH, we carried out an extensive review of animal studies and clinical trials about the transforming growth factor-β/SMAD signaling pathway, upregulation of tenascin-C, inflammation-dependent hypersecretion of CSF, systemic inflammatory response syndrome, and immune dysregulation. To identify the ideal treatment strategy, we discuss the predictive factors of shunt-dependent hydrocephalus between surgical clipping and endovascular coiling groups. The efficacy and safety of other surgical interventions including the endoscopic removal of an intraventricular hemorrhage, placement of an external ventricular drain, the use of intraventricular or cisternal fibrinolysis, and an endoscopic third ventriculostomy on shunt dependency following aSAH were also assessed. However, the optimal treatment is still controversial, and it necessitates further investigations. A better understanding of the pathogenesis of acute and chronic hydrocephalus following aSAH would facilitate the development of treatments and improve the outcome.

MRTFA: A critical protein in normal and malignant hematopoiesis and beyond

Myocardin-related transcription factor A (MRTFA) is a coactivator of serum response factor, a transcription factor that participates in several critical cellular functions including cell growth and apoptosis. MRTFA couples transcriptional regulation to actin cytoskeleton dynamics, and the transcriptional targets of the MRTFA–serum response factor complex include genes encoding cytoskeletal proteins as well as immediate early genes. Previous work has shown that MRTFA promotes the differentiation of many cell types, including various types of muscle cells and hematopoietic cells, and MRTFA's interactions with other protein partners broaden its cellular roles. However, despite being first identified as part of the recurrent t(1;22) chromosomal translocation in acute megakaryoblastic leukemia, the mechanisms by which MRTFA functions in malignant hematopoiesis have yet to be defined. In this review, we provide an in-depth examination of the structure, regulation, and known functions of MRTFA with a focus on hematopoiesis. We conclude by identifying areas of study that merit further investigation.

Fibroblasts treated with macrophage conditioned medium results in phenotypic shifts and changes in collagen organization

In tissue regeneration, the goal is to regenerate tissue similar to what was damaged or missing while preventing fibrotic scarring, which may lead to decreased mechanical strength and dissimilar tissue characteristics compared to native tissue. We believe collagen orientation plays a critical role in wound contraction and scarring and that it is modulated by myofibroblasts. We used macrophage conditioned medium to simulate complex events that can influence the fibroblast phenotype during the wound healing process. In addition to examining the effect of macrophage phenotype on fibroblasts, we inhibited focal adhesion kinase (FAK), Rho-associated protein kinase (ROCK), and myosin II for fibroblasts cultured on both tissue culture plastic and methacrylated gellan gum to understand how different pathways and materials influence fibroblast responses. Collagen orientation, α-SMA expression, focal adhesion area, and cell migration were altered by inhibition of FAK, ROCK, or myosin II and macrophage phenotype, along with the substrate. An increase in either focal adhesion area or α-smooth muscle actin (α-SMA) expression correlated with an aligned collagen orientation. Gellan gum hydrogels upregulated α-SMA expression in ROCK inhibited conditioned media and downregulated the FAK area in FAK and ROCK inhibited conditioned media. Myosin II had no impact on the α-SMA expression on the substrate compared to coverslip except for M2 conditioned medium. Gellan gum hydrogel significantly increased cell migration under FAK and Myosin II mediated conditioned media and unconditioned media. Collectively, our study examined how macrophage phenotype influences fibroblast response, which would be beneficial in controlling scar tissue formation.

Inhibiting TGF-[Formula: see text] 1-Mediated Cellular Processes as an Effective Strategy for the Treatment of Pulmonary Fibrosis with Chinese Herbal Medicines

Pulmonary fibrosis (PF) is a chronic and irreversible interstitial lung disease that even threatens the lives of some patients infected with COVID-19. PF is a multicellular pathological process, including the initial injuries of epithelial cells, recruitment of inflammatory cells, epithelial-mesenchymal transition, activation and differentiation of fibroblasts, etc. TGF-[Formula: see text]1 acts as a key effect factor that participates in these cellular processes of PF. Recently, much attention was paid to inhibiting TGF-[Formula: see text]1 mediated cell processes in the treatment of PF with Chinese herbal medicines (CHM), an important part of traditional Chinese medicine. Here, this review first summarized the effects of TGF-[Formula: see text]1 in different cellular processes of PF. Then, this review summarized the recent research on CHM (compounds, multi-components, single medicines and prescriptions) to directly and/or indirectly inhibit TGF-[Formula: see text]1 signaling (TLRs, PPARs, micrRNA, etc.) in PF. Most of the research focused on CHM natural compounds, including but not limited to alkaloids, flavonoids, phenols and terpenes. After review, the research perspectives of CHM on TGF-[Formula: see text]1 inhibition in PF were further discussed. This review hopes that revealing the inhibiting effects of CHM on TGF-[Formula: see text]1-mediated cellular processes of PF can promote CHM to be better understood and utilized, thus transforming the therapeutic activities of CHM into practice.

WJ‑MSCs intervention may relieve intrauterine adhesions in female rats via TGF‑&beta;1‑mediated Rho/ROCK signaling inhibition

Estrogen is a commonly used hormone in the adjuvant treatment of intrauterine adhesion (IUA), which can promote endometrial growth. Stem cell transplantation has also been reported to promote endometrial regeneration in IUA due to its potential differentiative capacity. Human Wharton's jelly mesenchymal stem cells (WJ-MSCs) are isolated from the umbilical cord, possess strong self-renewal and proliferative abilities, and are hypo-immunogenic and non-tumorigenic. Therefore, the present study aimed to investigate the therapeutic effects and underlying mechanism of WJ-MSCs transplantation with estrogen treatment, separately or as a combined therapy, on IUA. The IUA model was established using the ethanol damage method. A total of 50 Sprague-Dawley female rats were randomly divided into the control, IUA model, WJ-MSCs treatment, estrogen treatment and WJ-MSCs+ estrogen treatment groups (n=10/group). WJ-MSCs were injected three times at 5-day intervals. IUA rats in the estrogen group received 0.2 mg/kg estrogen through intragastric administration, once every 2 days for 8 weeks. Morphological changes were evaluated by hematoxylin-eosin staining. Immunohistochemical evaluations of pan-keratin, vimentin, transforming growth factor (TGF)-β1, RhoA, RhoB, RhoC, Rho-associated coiled-coil-containing protein kinase (ROCK)I, and ROCKII expression were performed in uterine tissue. After treatment, the uterine specimens were observed to have increased uterine thickness and gland numbers in all treatment groups compared with the IUA group; however, the degree of restoration in the independent WJ-MSCs and estrogen treatment groups was better than in the combined treatment group. Immunohistochemical analysis demonstrated that pan-keratin expression was increased, and RhoA, ROCKI and TGF-β1 expression was significantly inhibited in the WJ-MSCs and WJ-MSCs + estrogen treatment groups compared with the IUA group; however, the expression levels of these proteins were similar among all treatment groups. No change in vimentin expression was detected in any treatment group. The expression levels of RhoB, RhoC and ROCKII were clearly not affected by WJ-MSCs intervention alone. In conclusion, transplantation of WJ-MSCs may repair endometrial damage in IUA rats via TGF-β1-mediated inhibition of RhoA/ROCKI signaling.

Transforming Growth Factor-β: A Multifunctional Regulator of Cancer Immunity

Transforming growth factor-β (TGF-β) was originally identified as an anti-tumour cytokine. However, there is increasing evidence that it has important roles in the tumour microenvironment (TME) in facilitating cancer progression. TGF-β actively shapes the TME via modulating the host immunity. These actions are highly cell-type specific and complicated, involving both canonical and non-canonical pathways. In this review, we systemically update how TGF-β signalling acts as a checkpoint regulator for cancer immunomodulation. A better appreciation of the underlying pathogenic mechanisms at the molecular level can lead to the discovery of novel and more effective therapeutic strategies for cancer.

Transforming Growth Factor-β: A Multifunctional Regulator of Cancer Immunity

Simple Summary

Transforming growth factor beta (TGF-β) is a multifunctional cytokine that can restrict cancer onset but also promote cancer progression at late stages of cancer. The ability of TGF-β in producing diverse and sometimes opposing effects relies on its potential to control different cellular signalling and gene expression in distinct cell types, and environmental settings. The tumour promoting role of TGF-β is primarily mediated through its effects on the local tumour microenvironment (TME) of the cancer cells. In this review, we discuss the most recent research on the role and regulation of TGF-β, with a specific focus on its functions on promoting cancer progression through targeting different immune cells in the TME as well as its therapeutic perspectives.

Abstract

Transforming growth factor-β (TGF-β) was originally identified as an anti-tumour cytokine. However, there is increasing evidence that it has important roles in the tumour microenvironment (TME) in facilitating cancer progression. TGF-β actively shapes the TME via modulating the host immunity. These actions are highly cell-type specific and complicated, involving both canonical and non-canonical pathways. In this review, we systemically update how TGF-β signalling acts as a checkpoint regulator for cancer immunomodulation. A better appreciation of the underlying pathogenic mechanisms at the molecular level can lead to the discovery of novel and more effective therapeutic strategies for cancer.

Conditional reprogramming: next generation cell culture

Long-term primary culture of mammalian cells has been always difficult due to unavoidable senescence. Conventional methods for generating immortalized cell lines usually require manipulation of genome which leads to change of important biological and genetic characteristics. Recently, conditional reprogramming (CR) emerges as a novel next generation tool for long-term culture of primary epithelium cells derived from almost all origins without alteration of genetic background of primary cells. CR co-cultures primary cells with inactivated mouse 3T3-J2 fibroblasts in the presence of RHO-related protein kinase (ROCK) inhibitor Y-27632, enabling primary cells to acquire stem-like characteristics while retain their ability to fully differentiate. With only a few years' development, CR shows broad prospects in applications in varied areas including disease modeling, regenerative medicine, drug evaluation, drug discovery as well as precision medicine. This review is thus to comprehensively summarize and assess current progress in understanding mechanism of CR and its wide applications, highlighting the value of CR in both basic and translational researches and discussing the challenges faced with CR.

Conditional reprogramming: Modeling urological cancer and translation to clinics

Patient-derived models, including cell models (organoids and conditionally reprogrammed cells [CRCs]) and patient-derived xenografts, are urgently needed for both basic and translational cancer research. Conditional reprogramming (CR) technique refers to a co-culture system of primary human normal or tumor cells with irradiated murine fibroblasts in the presence of a Rho-associated kinase inhibitor to allow the primary cells to acquire stem cell properties and the ability to proliferate indefinitely in vitro without any exogenous gene or viral transfection. Considering its robust features, the CR technique may facilitate cancer research in many aspects. Under in vitro culturing, malignant CRCs can share certain genetic aberrations and tumor phenotypes with their parental specimens. Thus, tumor CRCs can promisingly be utilized for the study of cancer biology, the discovery of novel therapies, and the promotion of precision medicine. For normal CRCs, the characteristics of normal karyotype maintenance and lineage commitment suggest their potential in toxicity testing and regenerative medicine. In this review, we discuss the applications, limitations, and future potential of CRCs in modeling urological cancer and translation to clinics.

The effects of chronic cadmium exposure on the gut of Bufo gargarizans larvae at metamorphic climax: Histopathological impairments, microbiota changes and intestinal remodeling disruption

Cadmium (Cd) is carcinogenic to human and it also has adverse effects on aquatic life such as amphibian larvae. However, its influences on amphibian gut morphology and development as well as intestinal microbiota are still hardly understood. In this study, we examined the effects of chronic cadmium exposure on the gut of tadpoles at Gosner stage 42 of metamorphic climax by using Bufo gargarizans as a model species. Tadpoles were exposed to cadmium concentrations at 0, 5, 100 and 200 μg L^-1 from Gosner stage 26-42. The results showed that high cadmium (100 and 200 μg L^-1) exposure caused significant decrease of body length and weight but significant increase of intestinal length and weight. Moreover, severe histopathological damages were induced by high Cd exposure. In addition, microbial communities in the gut of tadpoles in high cadmium exposure groups were remarkably different from those in control group. Unexpectedly, species diversity and richness were higher in the intestinal microbiota of 200 μg L^-1 cadmium exposure group. Furthermore, the abundance of prevalent phyla, families and genera of intestinal microbiota were changed by cadmium exposure. Meanwhile, cadmium exposure perturbed gut renewal functions and the relative mRNA expression of genes involved in canonical and non-canonical Wnt signaling pathway was seriously affected by high cadmium exposure. We concluded that cadmium could be harmful to tadpole health by inducing intestinal histopathological damages, gut remodeling inhibition and intestinal microbiota alterations.

Lung-resident mesenchymal stromal cells are tissue-specific regulators of lung homeostasis

Until recently, data supporting the tissue-resident status of mesenchymal stromal cells (MSC) has been ambiguous since their discovery in the 1950-60s. These progenitor cells were first discovered as bone marrow-derived adult multipotent cells and believed to migrate to sites of injury, opposing the notion that they are residents of all tissue types. In recent years, however, it has been demonstrated that MSC can be found in all tissues and MSC from different tissues represent distinct populations with differential protein expression unique to each tissue type. Importantly, these cells are efficient mediators of tissue repair, regeneration, and prove to be targets for therapeutics, demonstrated by clinical trials (phase 1-4) for MSC-derived therapies for diseases like graft-versus-host-disease, multiple sclerosis, rheumatoid arthritis, and Crohn's disease. The tissue-resident status of MSC found in the lung is a key feature of their importance in the context of disease and injuries of the respiratory system, since these cells could be instrumental to providing more specific and targeted therapies. Currently, bone marrow-derived MSC have been established in the treatment of disease, including diseases of the lung. However, with lung-resident MSC representing a unique population with a different phenotypic and gene expression pattern than MSC derived from other tissues, their role in remediating lung inflammation and injury could provide enhanced efficacy over bone marrow-derived MSC methods. Through this review, lung-resident MSC will be characterized, using previously published data, by surface markers, gene expression patterns, and compared with bone-marrow MSC to highlight similarities and, importantly, differences in these cell types.

Targeting Rho-associated coiled-coil forming protein kinase (ROCK) in cardiovascular fibrosis and stiffening

Introduction: Pathological cardiac fibrosis, through excessive extracellular matrix protein deposition from fibroblasts and pro-fibrotic immune responses and vascular stiffening is associated with most forms of cardiovascular disease. Pathological cardiac fibrosis and stiffening can lead to heart failure and arrythmias and vascular stiffening may lead to hypertension. ROCK, a serine/threonine kinase downstream of the Rho-family of GTPases, may regulate many pro-fibrotic and pro-stiffening signaling pathways in numerous cell types.Areas covered: This article outlines the molecular mechanisms by which ROCK in fibroblasts, T helper cells, endothelial cells, vascular smooth muscle cells, and macrophages mediate fibrosis and stiffening. We speculate on how ROCK could be targeted to inhibit cardiovascular fibrosis and stiffening.Expert opinion: Critical gaps in knowledge must be addressed if ROCK inhibitors are to be used in the clinic. Numerous studies indicate that each ROCK isoform may play differential roles in regulating fibrosis and may have opposing roles in specific tissues. Future work needs to highlight the isoform- and tissue-specific contributions of ROCK in fibrosis, and how isoform-specific ROCK inhibitors in murine models and in clinical trials affect the pathophysiology of cardiac fibrosis and stiffening. This could progress knowledge regarding new treatments for heart failure, arrythmias and hypertension and the repair processes after myocardial infarction.

Molecular determinants of mesenchymal cell activation in fibroproliferative diseases

Uncontrolled scarring, or fibrosis, can interfere with the normal function of virtually all tissues of the body, ultimately leading to organ failure and death. Fibrotic diseases represent a major cause of death in industrialized countries. Unfortunately, no curative treatments for these conditions are yet available, highlighting the critical need for a better fundamental understanding of molecular mechanisms that may be therapeutically tractable. The ultimate indispensable effector cells responsible for deposition of extracellular matrix proteins that comprise scars are mesenchymal cells, namely fibroblasts and myofibroblasts. In this review, we focus on the biology of these cells and the molecular mechanisms that regulate their pertinent functions. We discuss key pro-fibrotic mediators, signaling pathways, and transcription factors that dictate their activation and persistence. Because of their possible clinical and therapeutic relevance, we also consider potential brakes on mesenchymal cell activation and cellular processes that may facilitate myofibroblast clearance from fibrotic tissue-topics that have in general been understudied.

Elevated BMP and Mechanical Signaling Through YAP1/RhoA Poises FOP Mesenchymal Progenitors for Osteogenesis

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disease characterized by the formation of extraskeletal bone, or heterotopic ossification (HO), in soft connective tissues such as skeletal muscle. All familial and sporadic cases with a classic clinical presentation of FOP carry a gain-of-function mutation (R206H; c.617 G > A) in ACVR1, a cell surface receptor that mediates bone morphogenetic protein (BMP) signaling. The BMP signaling pathway is recognized for its chondro/osteogenic-induction potential, and HO in FOP patients forms ectopic but qualitatively normal endochondral bone tissue through misdirected cell fate decisions by tissue-resident mesenchymal stem cells. In addition to biochemical ligand-receptor signaling, mechanical cues from the physical environment are transduced to activate intracellular signaling, a process known as mechanotransduction, and can influence cell fates. Utilizing an established mesenchymal stem cell model of mouse embryonic fibroblasts (MEFs) from the Acvr1R206H/+ mouse model that mimics the human disease, we demonstrated that activation of the mechanotransductive effectors Rho/ROCK and YAP1 are increased in Acvr1R206H/+ cells. We show that on softer substrates, a condition associated with low mechanical signaling, the morphology of Acvr1R206H/+ cells is similar to the morphology of control Acvr1+/+ cells on stiffer substrates, a condition that activates mechanotransduction. We further determined that Acvr1R206H/+ cells are poised for osteogenic differentiation, expressing increased levels of chondro/osteogenic markers compared with Acvr1+/+ cells. We also identified increased YAP1 nuclear localization in Acvr1R206H/+ cells, which can be rescued by either BMP inhibition or Rho antagonism. Our results establish RhoA and YAP1 signaling as modulators of mechanotransduction in FOP and suggest that aberrant mechanical signals, combined with and as a result of the increased BMP pathway signaling through mutant ACVR1, lead to misinterpretation of the cellular microenvironment and a heightened sensitivity to mechanical stimuli that promotes commitment of Acvr1R206H/+ progenitor cells to chondro/osteogenic lineages.

Di-(2-Ethylhexyl) Phthalate Promotes Release of Tissue Factor-Bearing Microparticles From Macrophages via the TGFβ1/Smad/PAI-1 Signaling Pathway

BACKGROUND

Plasminogen activator inhibitor type 1 promotes formation of endothelial microparticles with procoagulant activity. However, it remains unclear whether di-(2-ethylhexyl) phthalate, a peroxisome proliferator-activated receptor α agonist, influences microparticle formation.

MATERIALS AND METHODS

The effect of di-(2-ethylhexyl) phthalate on release of tissue factor-bearing microparticles was investigated using human M1 macrophages.

RESULTS

Exposure of M1 macrophages to di-(2-ethylhexyl) phthalate significantly upregulated expression of plasminogen activator inhibitor type 1, whereas incubation of macrophages with small interfering RNA for peroxisome proliferator-activated receptor α attenuated it. Di-(2-ethylhexyl) phthalate significantly increased the tissue factor protein level in culture supernatants of M1 macrophages, but not M2 macrophages. After purification of proteins by centrifugal filtration, western blotting detected 2 high molecular weight bands of tissue factor-bearing microparticles in culture supernatants of M1 macrophages. The upper band showed binding to factor VIIa and tissue factor pathway inhibitor, unlike the lower band. This suggested heterogeneity of the procoagulant activity of tissue factor-bearing microparticles, presumably dependent upon encryption/decryption of tissue factor. Phosphatidylserine contributes to tissue factor decryption, and western blotting revealed that the density of phosphatidylserine was reduced in the upper tissue factor band compared with the lower band. Di-(2-ethylhexyl) phthalate also upregulated transforming growth factor-β1 protein production by M1 macrophages. Moreover, silencing of Smad2, Smad3 or Smad4 attenuated plasminogen activator inhibitor type 1 expression and tissue factor-release from macrophages after di-(2-ethylhexyl) phthalate stimulation.

CONCLUSIONS

Di-(2-ethylhexyl) phthalate promotes formation of tissue factor-bearing microparticles in human M1 macrophages via the transforming growth factor-β1/Smad/ plasminogen activator inhibitor type 1 signaling pathway.

The migration and fusion events related to ROCK activity strongly influence the morphology of chicken embryo intestinal organoids

The method of organoid culture has become a tool widely used in gastrointestinal research, but so far, the migration of organoids derived from gut epithelium and formed in 3D Matrigel matrix has not been reported and studied. The intestinal epithelial tissue derived from 19-day-old chicken embryo was cultured in Matrigel and the dynamic properties of the forming organoids were analyzed by time-lapse image analysis. It was observed that about one in ten organoids actively moved through the matrix, at a speed of 10-20 μm/h. Moreover, rotation was observed in the majority of organoids that did not migrate long distances. The fusion events took place between organoids, which collided during the movement or growth. In our previous paper, we showed that the presence of Toll-like receptor 4 ligand, Escherichia coli lipopolysaccharide (LPS, 1 μg/ml), increased the mean organoid diameter. Here, we confirm this result and demonstrate that the Rho-associated protein kinase (ROCK) inhibitor Y-27632 (10 μM) did not completely abolish organoid migration, but prevented the fusion events, in both LPS-treated and untreated cultures. In consequence, in the presence of Y-27632, the differences between cultures incubated with and without LPS were not visible. We conclude that migration and fusion of organoids may influence their morphology and suggest that these phenomena should be taken into account during the design of experimental settings.

Cocaine addicted to cytoskeletal change and a fibrosis high

Cocaine is one of the most widely abused illicit drugs due to its euphoric and addictive properties. Cocaine-mediated cognitive impairments are the result of dynamic cytoskeletal rearrangements involved in mediating structural and behavioural plasticity. Cytoskeletal changes initiated following cocaine abuse are regulated by the Rho family of GTPases with significant downstream activity in key actin binding proteins. Moreover, signalling via the endoplasmic reticulum chaperone protein, sigma-1 receptor has highlighted the possibility of cocaine regulated pathology in other organ systems. However, the question of whether upstream stimulation of such a high affinity binding receptor is directly involved in cocaine-mediated cytoskeletal changes at present remains unknown. In this review, we describe the functional role of key cytoskeletal regulators in response to cocaine-induced signalling cues. In addition, we ascertain the extent of whether global cytoskeletal modulators involved in cocaine-induced neurological stimulation can be used as a platform for future studies into elucidating its fibrotic potential within the hepatic microenvironment. A focus on aspects still poorly understood relating to the nonneuronal pathological impact of cocaine is discussed in the sphere of hepatic dysregulation. Lastly, we suggest that cocaine may mediate its pathological capacity via the sigma1 receptor in regulating hepatoxicity, hepatic stellate cells activity, cytoskeletal dynamics, and the transcriptional regulation of key hepato-fibrogenic modulators.

TGF-β1-induced deposition of provisional extracellular matrix by tracheal basal cells promotes epithelial-to-mesenchymal transition in a c-Jun NH2-terminal kinase-1-dependent manner

Epithelial cells have been suggested as potential drivers of lung fibrosis, although the epithelial-dependent pathways that promote fibrogenesis remain unknown. Extracellular matrix is increasingly recognized as an environment that can drive cellular responses in various pulmonary diseases. In this study, we demonstrate that transforming growth factor-β1 (TGF-β1)-stimulated mouse tracheal basal (MTB) cells produce provisional matrix proteins in vitro, which initiate mesenchymal changes in subsequently freshly plated MTB cells via Rho kinase- and c-Jun NH2-terminal kinase (JNK1)-dependent processes. Repopulation of decellularized lung scaffolds, derived from mice with bleomycin-induced fibrosis or from patients with idiopathic pulmonary fibrosis, with wild-type MTB cells resulted in a loss of epithelial gene expression and augmentation of mesenchymal gene expression compared with cells seeded into decellularized normal lungs. In contrast, Jnk1-/- basal cells seeded into fibrotic lung scaffolds retained a robust epithelial expression profile, failed to induce mesenchymal genes, and differentiated into club cell secretory protein-expressing cells. This new paradigm wherein TGF-β1-induced extracellular matrix derived from MTB cells activates a JNK1-dependent mesenchymal program, which impedes subsequent normal epithelial cell homeostasis, provides a plausible scenario of chronic aberrant epithelial repair, thought to be critical in lung fibrogenesis. This study identifies JNK1 as a possible target for inhibition in settings wherein reepithelialization is desired.

Transcriptional and post-transcriptional regulation of the genes encoding the small GTPases RhoA, RhoB, and RhoC: implications for the pathogenesis of human diseases

Rho GTPases are highly conserved proteins that play critical roles in many cellular processes including actin dynamics, vesicular trafficking, gene transcription, cell-cycle progression, and cell adhesion. The main mode of regulation of Rho GTPases is through guanine nucleotide binding (cycling between an active GTP-bound form and an inactive GDP-bound form), but transcriptional, post-transcriptional, and post-translational modes of Rho regulation have also been described. In the present review, we summarize recent progress on the mechanisms that control the expression of the three members of the Rho-like subfamily (RhoA, RhoB, and RhoC) at the level of gene transcription as well as their post-transcriptional regulation by microRNAs. We also discuss the progress made in deciphering the mechanisms of cross-talk between Rho proteins and the transforming growth factor β signaling pathway and their implications for the pathogenesis of human diseases such as cancer metastasis and fibrosis.

The correlation between pulmonary fibrosis and methylation of peripheral Smad3 in cases of pigeon breeder's lung in a Chinese Uygur population

Smad3 is a key protein in the transforming growth factor-beta (TGF-β)/Smad signaling pathway, which is involved in fibrosis in many organs. We investigated the relationship between Smad3 gene methylation and pulmonary fibrosis in pigeon breeder's lung (PBL). Twenty Uygur PBL patients with pulmonary fibrosis in Kashi between October 2015 and March 2016 were enrolled. Twenty PBL-free pigeon breeders and 20 healthy non-pigeon breeders enrolled during the same period constituted the negative and normal control groups, respectively. Participants’ data and peripheral blood samples were collected, and three Smad3 CpG loci were examined. Distributions of CpG_2 and CpG_4 methylation rates did not differ across groups, whereas distributions of CpG_3 methylation rates were significantly different among the three groups. The CpG_3 methylation rate was significantly lower in the patient group than in the negative control group. Smad3 mRNA expression was significantly higher in the patient group than in the negative control group but did not differ between the two control groups. TGF-βlevels were significantly higher in the patient group than in either control group (both P<0.01). Smad3 gene methylation and Smad3 mRNA expression were negatively correlated, with a correlation coefficient of -0.84. The number of pigeons bred during the preceding three months was positively correlated with Smad3 mRNA expression, with a correlation coefficient of 0.77. Smad3 gene hypomethylation might promote pulmonary fibrosis in Uygur PBL patients via increased Smad3 mRNA expression. Smad3 methylation, Smad3 mRNA expression and TGF-β level were correlated with the number of pigeons bred by patients.

Syndecan-2 Attenuates Radiation-induced Pulmonary Fibrosis and Inhibits Fibroblast Activation by Regulating PI3K/Akt/ROCK Pathway via CD148

Radiation-induced pulmonary fibrosis is a severe complication of patients treated with thoracic irradiation. We have previously shown that syndecan-2 reduces fibrosis by exerting alveolar epithelial cytoprotective effects. Here, we investigate whether syndecan-2 attenuates radiation-induced pulmonary fibrosis by inhibiting fibroblast activation. C57BL/6 wild-type mice and transgenic mice that overexpress human syndecan-2 in alveolar macrophages were exposed to 14 Gy whole-thoracic radiation. At 24 weeks after irradiation, lungs were collected for histological, protein, and mRNA evaluation of pulmonary fibrosis, profibrotic gene expression, and α-smooth muscle actin (α-SMA) expression. Mouse lung fibroblasts were activated with transforming growth factor (TGF)-β1 in the presence or absence of syndecan-2. Cell proliferation, migration, and gel contraction were assessed at different time points. Irradiation resulted in significantly increased mortality and pulmonary fibrosis in wild-type mice that was associated with elevated lung expression of TGF-β1 downstream target genes and cell death compared with irradiated syndecan-2 transgenic mice. In mouse lung fibroblasts, syndecan-2 inhibited α-SMA expression, cell contraction, proliferation, and migration induced by TGF-β1. Syndecan-2 attenuated phosphoinositide 3-kinase/serine/threonine kinase/Rho-associated coiled-coil kinase signaling and serum response factor binding to the α-SMA promoter. Syndecan-2 attenuates pulmonary fibrosis in mice exposed to radiation and inhibits TGF-β1-induced fibroblast-myofibroblast differentiation, migration, and proliferation by down-regulating phosphoinositide 3-kinase/serine/threonine kinase/Rho-associated coiled-coil kinase signaling and blocking serum response factor binding to the α-SMA promoter via CD148. These findings suggest that syndecan-2 has potential as an antifibrotic therapy in radiation-induced lung fibrosis.

Involvement of Rho-associated coiled-coil kinase signaling inhibition in TGF-β1/Smad2, 3 signal transduction in vitro

AIM

To research the effect of Y-27632, a selective Rho-associated coiled-coil kinase (ROCK) inhibitor, on TGF-β1/Smad2, 3 signal transduction in ocular Tenon's capsule fibroblasts (OTFs).

METHODS

Primary ocular Tenon's capsule fibroblasts had been cultured in vitro. The effect of Y27632 on proliferation of OTF stimulated by lysophosphatidic acid (LPA) was evaluated by MTT colorimetric assay so as to sift out the proper concentrations range of Y-27632 for the next experiment. Real time-polymerase chain reactor (RT-PCR) was to analyze the changes of Smad2 and Smad3 genes of cells affected by Y-27632, though unaffected by transforming growth factor-beta1 (TGF-β1). Proteins of Smad2, Smad3, phosphorylated Smad2 (Ser245/250/255), and phosphorylated Smad3 (Ser423/425/203) were respectively quantified by Western blot after OTFs were successively incubated by TGF-β1 and Y-27632. Meanwhile, α-smooth muscular actin (α-SMA) protein was also quantified after the small intervening gene fragments of human Smad2 and Smad3 were designed, synthesized, and then transfected to OTFs.

RESULTS

Y-27632 significantly inhibited OTFs proliferation stimulated by LPA. Also Y-27632 significantly suppressed the expressions of Smad2 mRNA, Smad2, 3 proteins expressions, Smad3 phosphorylation at the carboxylic terminals of Ser423/425/203 which had been radically promoted by TGF-β1. SiRNA-Smad2, 3 suppressed α-SMA expressions, but less effectively than Y-27632.

CONCLUSION

The inhibition of ROCK signaling may be a potential therapeutic candidate for the treatment of the filtration channel fibrosis.

Transforming growth factor-β enhances Rho-kinase activity and contraction in airway smooth muscle via the nucleotide exchange factor ARHGEF1

Key points

Transforming growth‐factor‐β (TGF‐β) and RhoA/Rho‐kinase are independently implicated in the airway hyper‐responsiveness associated with asthma, but how these proteins interact is not fully understood.

We examined the effects of pre‐treatment with TGF‐β on expression and activity of RhoA, Rho‐kinase and ARHGEF1, an activator of RhoA, as well as on bradykinin‐induced contraction, in airway smooth muscle.

TGF‐β enhanced bradykinin‐induced RhoA translocation, Rho‐kinase‐dependent phosphorylation and contraction, but partially suppressed bradykinin‐induced RhoA activity (RhoA‐GTP content).

TGF‐β enhanced the expression of ARHGEF1, while a small interfering RNA against ARHGEF1 and a RhoGEF inhibitor prevented the effects of TGF‐β on RhoA and Rho‐kinase activity and contraction, respectively.

ARHGEF1 expression was also enhanced in airway smooth muscle from asthmatic patients and ovalbumin‐sensitized mice.

ARHGEF1 is a key TGF‐β target gene, an important regulator of Rho‐kinase activity and therefore a potential therapeutic target for the treatment of asthmatic airway hyper‐responsiveness.

Abstract

Transforming growth factor‐β (TGF‐β), RhoA/Rho‐kinase and Src‐family kinases (SrcFK) have independently been implicated in airway hyper‐responsiveness, but how they interact to regulate airway smooth muscle contractility is not fully understood. We found that TGF‐β pre‐treatment enhanced acute contractile responses to bradykinin (BK) in isolated rat bronchioles, and inhibitors of RhoGEFs (Y16) and Rho‐kinase (Y27632), but not the SrcFK inhibitor PP2, prevented this enhancement. In cultured human airway smooth muscle cells (hASMCs), TGF‐β pre‐treatment enhanced the protein expression of the Rho guanine nucleotide exchange factor ARHGEF1, MLC₂₀, MYPT‐1 and the actin‐severing protein cofilin, but not of RhoA, ROCK2 or c‐Src. In hASMCs, acute treatment with BK triggered subcellular translocation of ARHGEF1 and RhoA and enhanced auto‐phosphorylation of SrcFK and phosphorylation of MYPT1 and MLC₂₀, but induced de‐phosphorylation of cofilin. TGF‐β pre‐treatment amplified the effects of BK on RhoA translocation and MYPT1/MLC₂₀ phosphorylation, but suppressed the effects of BK on RhoA‐GTP content, SrcFK auto‐phosphorylation and cofilin de‐phosphorylation. In hASMCs, an ARHGEF1 small interfering RNA suppressed the effects of BK and TGF‐β on RhoA‐GTP content, RhoA translocation and MYPT1 and MLC₂₀ phosphorylation, but minimally influenced the effects of TGF‐β on cofilin expression and phosphorylation. ARHGEF1 expression was also enhanced in ASMCs of asthmatic patients and in lungs of ovalbumin‐sensitized mice. Our data indicate that TGF‐β enhances BK‐induced contraction, RhoA translocation and Rho‐kinase activity in airway smooth muscle largely via ARHGEF1, but independently of SrcFK and total RhoA‐GTP content. A role for smooth muscle ARHGEF1 in asthmatic airway hyper‐responsiveness is worthy of further investigation.

Transforming growth‐factor‐β (TGF‐β) and RhoA/Rho‐kinase are independently implicated in the airway hyper‐responsiveness associated with asthma, but how these proteins interact is not fully understood.

We examined the effects of pre‐treatment with TGF‐β on expression and activity of RhoA, Rho‐kinase and ARHGEF1, an activator of RhoA, as well as on bradykinin‐induced contraction, in airway smooth muscle.

TGF‐β enhanced bradykinin‐induced RhoA translocation, Rho‐kinase‐dependent phosphorylation and contraction, but partially suppressed bradykinin‐induced RhoA activity (RhoA‐GTP content).

TGF‐β enhanced the expression of ARHGEF1, while a small interfering RNA against ARHGEF1 and a RhoGEF inhibitor prevented the effects of TGF‐β on RhoA and Rho‐kinase activity and contraction, respectively.

ARHGEF1 expression was also enhanced in airway smooth muscle from asthmatic patients and ovalbumin‐sensitized mice.

ARHGEF1 is a key TGF‐β target gene, an important regulator of Rho‐kinase activity and therefore a potential therapeutic target for the treatment of asthmatic airway hyper‐responsiveness.