TRPV4 channel inhibits TGF-β1-induced proliferation of hepatic stellate cells

TRPV4 overactivation enhances cellular contractility and drives ocular hypertension in TGFβ2 overexpressing eyes

The risk for developing primary open-angle glaucoma (POAG) correlates with the magnitude of ocular hypertension (OHT) and the concentration of transforming growth factor-β2 (TGFβ2) in the aqueous humor. Effective treatment of POAG requires detailed understanding of interaction between pressure sensing mechanisms in the trabecular meshwork (TM) and biochemical risk factors. Here, we employed molecular, optical, electrophysiological and tonometric strategies to establish the role of TGFβ2 in transcription and functional expression of mechanosensitive channel isoforms alongside studies of TM contractility in biomimetic hydrogels, and intraocular pressure (IOP) regulation in a mouse model of TGFβ2 -induced OHT. TGFβ2 upregulated expression of TRPV4 and PIEZO1 transcripts and time-dependently augmented functional TRPV4 activation. TRPV4 activation induced TM contractility whereas pharmacological inhibition suppressed TGFβ2-induced hypercontractility and abrogated OHT in eyes overexpressing TGFβ2. Trpv4-deficient mice resisted TGFβ2-driven increases in IOP. Nocturnal OHT was not additive to TGFβ-evoked OHT. Our study establishes the fundamental role of TGFβ as a modulator of mechanosensing in nonexcitable cells, identifies TRPV4 channel as the final common mechanism for TM contractility and circadian and pathological OHT and offers insights future treatments that can lower IOP in the sizeable cohort of hypertensive glaucoma patients that resist current treatments.

Abnormal metabolism in hepatic stellate cells: Pandora's box of MAFLD related hepatocellular carcinoma

Metabolic associated fatty liver disease (MAFLD) is a significant risk factor for the development of hepatocellular carcinoma (HCC). Hepatic stellate cells (HSCs), as key mediators in liver injury response, are believed to play a crucial role in the repair process of liver injury. However, in MAFLD patients, the normal metabolic and immunoregulatory mechanisms of HSCs become disrupted, leading to disturbances in the local microenvironment. Abnormally activated HSCs are heavily involved in the initiation and progression of HCC. The metabolic disorders and abnormal activation of HSCs not only initiate liver fibrosis but also contribute to carcinogenesis. In this review, we provide an overview of recent research progress on the relationship between the abnormal metabolism of HSCs and the local immune system in the liver, elucidating the mechanisms of immune imbalance caused by abnormally activated HSCs in MAFLD patients. Based on this understanding, we discuss the potential and challenges of metabolic-based and immunology-based mechanisms in the treatment of MAFLD-related HCC, with a specific focus on the role of HSCs in HCC progression and their potential as targets for anti-cancer therapy. This review aims to enhance researchers' understanding of the importance of HSCs in maintaining normal liver function and highlights the significance of HSCs in the progression of MAFLD-related HCC.

The effects of high-intensity interval training and Iranian propolis extract on serum levels of TRPV4 and CYP2E1 proteins in patients with nonalcoholic fatty liver

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of liver failure, fibrosis, cirrhosis, and liver cancer, which can eventually lead to death.

AIM

To investigate the effects of high-intensity interval training (HIIT) and iranian propolis extract on serum levels of transient receptor potential cation channel subfamily V member 4 (TRPV4) and cytochrome P450 2E1 (CYP2E1) proteins in patients with NAFLD.

METHODS

Thirty-two patients with NAFLD (mean±standard deviation of age: 45.1±3.6 years; body mass index: 30.0±3.6 kg/m2) were assigned in a randomized control trial to one of the following groups: HIIT (n=8), propolis supplement (n=8), propolis + HIIT (n=8), and controls (n=8). The subjects participated in eight weeks of HIIT (one bout of 1-min intervals at 80-95% of the maximal heart-rate, interspersed by two min at 50-55% of the reserve heart-rate). The Propolis supplement was taken three times a day by the patients in the form of 50 mg tablet after the main meals. Body composition, liver injury test (eg; Alanine- and Aspartate- aminotransferase levels), liver ultrasound and serum levels of TRPV4 and CYP2E1 were measured before and after intervention. One-way analysis of variance was used to compare post-tests among the groups.

RESULTS

HIIT significantly reduced serum levels of TRPV4 protein (p=0.001). The reduction in CYP2E1 was not significant in HIIT group (p=0.075). Propolis consumption had no significant effect on serum levels of CYP2E1 protein (p=0.059), and TRPV4 (p=0.072). There was a significant decrease in TRPV4 and CYP2E1 in the HIIT (p=0.001) and propolis supplement (p=0.032) groups.

CONCLUSION

HIIT and propolis supplementation can be used to reduce TRPV4 and CYP2E1, which in turn reduces oxidative stress and inflammation in patients with NAFLD.

Role of TRP Channels in Liver-Related Diseases

The liver plays a crucial role in preserving the homeostasis of an entire organism by metabolizing both endogenous and exogenous substances, a process that relies on the harmonious interactions of hepatocytes, hepatic stellate cells (HSCs), Kupffer cells (KCs), and vascular endothelial cells (ECs). The disruption of the liver's normal structure and function by diverse pathogenic factors imposes a significant healthcare burden. At present, most of the treatments for liver disease are palliative in nature, rather than curative or restorative. Transient receptor potential (TRP) channels, which are extensively expressed in the liver, play a crucial role in regulating intracellular cation concentration and serve as the origin or intermediary stage of certain signaling pathways that contribute to liver diseases. This review provides an overview of recent developments in liver disease research, as well as an examination of the expression and function of TRP channels in various liver cell types. Furthermore, we elucidate the molecular mechanism by which TRP channels mediate liver injury, liver fibrosis, and hepatocellular carcinoma (HCC). Ultimately, the present discourse delves into the current state of research and extant issues pertaining to the targeting of TRP channels in the treatment of liver diseases and other ailments. Despite the numerous obstacles encountered, TRP channels persist as an extremely important target for forthcoming clinical interventions aimed at treating liver diseases.

TRP (transient receptor potential) ion channel family: structures, biological functions and therapeutic interventions for diseases

Transient receptor potential (TRP) channels are sensors for a variety of cellular and environmental signals. Mammals express a total of 28 different TRP channel proteins, which can be divided into seven subfamilies based on amino acid sequence homology: TRPA (Ankyrin), TRPC (Canonical), TRPM (Melastatin), TRPML (Mucolipin), TRPN (NO-mechano-potential, NOMP), TRPP (Polycystin), TRPV (Vanilloid). They are a class of ion channels found in numerous tissues and cell types and are permeable to a wide range of cations such as Ca²⁺, Mg²⁺, Na⁺, K⁺, and others. TRP channels are responsible for various sensory responses including heat, cold, pain, stress, vision and taste and can be activated by a number of stimuli. Their predominantly location on the cell surface, their interaction with numerous physiological signaling pathways, and the unique crystal structure of TRP channels make TRPs attractive drug targets and implicate them in the treatment of a wide range of diseases. Here, we review the history of TRP channel discovery, summarize the structures and functions of the TRP ion channel family, and highlight the current understanding of the role of TRP channels in the pathogenesis of human disease. Most importantly, we describe TRP channel-related drug discovery, therapeutic interventions for diseases and the limitations of targeting TRP channels in potential clinical applications.

CD73/NT5E-mediated ubiquitination of AURKA regulates alcohol-related liver fibrosis via modulating hepatic stellate cell senescence

Alcohol-related liver disease (ALD) is the most common chronic liver disease worldwide; however, no effective treatment to prevent the progression of alcohol-related liver fibrosis (ALF) is available. CD73/NT5E, a nucleotidase, controls cellular homeostasis by combining extracellular purinergic signaling with intracellular kinase activity and gene transcription and is associated with cell proliferation, differentiation, and death. In this study, we demonstrated that CD73/NT5E had a more significant regulatory effect on the activation, proliferation, and apoptosis of HSCs compared with that of CD39/ENTPD1. We examined the expression of CD73/NT5E in the normal and fibrotic human livers. The absence of CD73/NT5E was protective in mouse models of ALF. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that CD73/NT5E overexpression was related to the p53 signaling pathway, which regulates cell senescence. Proteins interacting with p53 were predicted using the STRING database. The overlap between proteomic analysis and STRING databases was for Aurora kinase A (AURKA), a cell cycle-regulated kinase. Coimmunoprecipitation (co-IP) assay and molecular docking confirmed that CD73/NT5E directly interacted with AURKA. We found that overexpression of CD73/NT5E inhibited AURKA ubiquitination, whereas p53 signaling was downregulated. Mechanistically, CD73/NT5E regulated ALF and the activation and senescence of stellate cells by binding to AURKA. These findings indicate that CD73/NT5E is a potential therapeutic target for ALF.

Hydrogel cultures reveal Transient Receptor Potential Vanilloid 4 regulation of myofibroblast activation and proliferation in valvular interstitial cells

As aortic valve stenosis develops, valve tissue becomes stiffer. In response to this change in environmental mechanical stiffness, valvular interstitial cells (VICs) activate into myofibroblasts. We aimed to investigate the role of mechanosensitive calcium channel Transient Receptor Potential Vanilloid type 4 (TRPV4) in stiffness induced myofibroblast activation. We verified TRPV4 functionality in VICs using live calcium imaging during application of small molecule modulators of TRPV4 activity. We designed hydrogel biomaterials that mimic mechanical features of healthy or diseased valve tissue microenvironments, respectively, to investigate the role of TRPV4 in myofibroblast activation and proliferation. Our results show that TRPV4 regulates VIC proliferation in a microenvironment stiffness-independent manner. While there was a trend toward inhibiting myofibroblast activation on soft microenvironments during TRPV4 inhibition, we observed near complete deactivation of myofibroblasts on stiff microenvironments. We further identified Yes-activated protein (YAP) as a downstream target for TRPV4 activity on stiff microenvironments. Mechanosensitive TRPV4 channels regulate VIC myofibroblast activation, whereas proliferation regulation is independent of the microenvironmental stiffness. Collectively, the data suggests differential regulation of stiffness-induced proliferation and myofibroblast activation. Our data further suggest a regulatory role for TRPV4 regarding YAP nuclear localization. TRPV4 is an important regulator for VIC myofibroblast activation, which is linked to the initiation of valve fibrosis. Although more validation studies are necessary, we suggest TRPV4 as a promising pharmaceutical target to slow aortic valve stenosis progression.

Role of Transient Receptor Potential Vanilloid 4 in Vascular Function

Transient receptor potential vanilloid 4 (TRPV4) channels are widely expressed in systemic tissues and can be activated by many stimuli. TRPV4, a Ca²⁺-permeable cation channel, plays an important role in the vasculature and is implicated in the regulation of cardiovascular homeostasis processes such as blood pressure, vascular remodeling, and pulmonary hypertension and edema. Within the vasculature, TRPV4 channels are expressed in smooth muscle cells, endothelial cells, and perivascular nerves. The activation of endothelial TRPV4 contributes to vasodilation involving nitric oxide, prostacyclin, and endothelial-derived hyperpolarizing factor pathways. TRPV4 activation also can directly cause vascular smooth muscle cell hyperpolarization and vasodilation. In addition, TRPV4 activation can evoke constriction in some specific vascular beds or under some pathological conditions. TRPV4 participates in the control of vascular permeability and vascular damage, particularly in the lung capillary endothelial barrier and lung injury. It also participates in vascular remodeling regulation mainly by controlling vasculogenesis and arteriogenesis. This review examines the role of TRPV4 in vascular function, particularly in vascular dilation and constriction, vascular permeability, vascular remodeling, and vascular damage, along with possible mechanisms, and discusses the possibility of targeting TRPV4 for therapy.

Pathological matrix stiffness promotes cardiac fibroblast differentiation through the POU2F1 signaling pathway

Cardiac fibroblast (CF) differentiation into myofibroblasts is a crucial cause of cardiac fibrosis, which increases in the extracellular matrix (ECM) stiffness. The increased stiffness further promotes CF differentiation and fibrosis. However, the molecular mechanism is still unclear. We used bioinformatics analysis to find new candidates that regulate the genes involved in stiffness-induced CF differentiation, and found that there were binding sites for the POU-domain transcription factor, POU2F1 (also known as Oct-1), in the promoters of 50 differentially expressed genes (DEGs) in CFs on the stiffer substrate. Immunofluorescent staining and Western blotting revealed that pathological stiffness upregulated POU2F1 expression and increased CF differentiation on polyacrylamide hydrogel substrates and in mouse myocardial infarction tissue. A chromatin immunoprecipitation assay showed that POU2F1 bound to the promoters of fibrosis repressors IL1R2, CD69, and TGIF2. The expression of these fibrosis repressors was inhibited on pathological substrate stiffness. Knockdown of POU2F1 upregulated these repressors and attenuated CF differentiation on pathological substrate stiffness (35 kPa). Whereas, overexpression of POU2F1 downregulated these repressors and enhanced CF differentiation. In conclusion, pathological stiffness upregulates the transcription factor POU2F1 to promote CF differentiation by inhibiting fibrosis repressors. Our work elucidated the crosstalk between CF differentiation and the ECM and provided a potential target for cardiac fibrosis treatment.

TRPV4 Mediates Cardiac Fibrosis via the TGF-β1/Smad3 Signaling Pathway in Diabetic Rats

Emerging evidence shows that the transient receptor potential vanilloid 4 (TRPV4) channel is involved in fibrosis in many organs. However, its role in diabetic cardiac fibrosis remains unclear. Our aim was to evaluate the expression level of TRPV4 in the diabetic heart and clarify its role in diabetes-induced cardiac fibrosis. A diabetic animal model was induced by a single intraperitoneal injection of streptozotocin into Sprague-Dawley rats. We also investigated cardiac fibroblasts isolated from neonatal Sprague-Dawley rats. TRPV4 expression was significantly upregulated in both diabetic myocardium and cardiac fibroblasts cultured in high-glucose medium. Masson's trichrome staining revealed that the TRPV4 antagonist HC067047 attenuated the diabetes-induced cardiac fibrosis. Furthermore, HC067047 reduced collagen Ι synthesis and suppressed the transforming growth factor beta 1 (TGF-β1) level as well as the phosphorylation of Smad3 in the diabetic heart. In addition, the TRPV4 antagonist inhibited the proliferation of cardiac fibroblasts, collagen Ι synthesis, and activation of the TGF-β1/Smad3 signaling pathway induced by high-glucose culture medium. Our findings demonstrate that the upregulation of TRPV4 expression mediates diabetic cardiac fibrosis via activation of the TGF-β1/Smad3 signaling pathway.

Ion Channels Orchestrate Pancreatic Ductal Adenocarcinoma Progression and Therapy

Pancreatic ductal adenocarcinoma is a devastating disease with a dismal prognosis. Therapeutic interventions are largely ineffective. A better understanding of the pathophysiology is required. Ion channels contribute substantially to the "hallmarks of cancer." Their expression is dysregulated in cancer, and they are "misused" to drive cancer progression, but the underlying mechanisms are unclear. Ion channels are located in the cell membrane at the interface between the intracellular and extracellular space. They sense and modify the tumor microenvironment which in itself is a driver of PDAC aggressiveness. Ion channels detect, for example, locally altered proton and electrolyte concentrations or mechanical stimuli and transduce signals triggered by these microenvironmental cues through association with intracellular signaling cascades. While these concepts have been firmly established for other cancers, evidence has emerged only recently that ion channels are drivers of PDAC aggressiveness. Particularly, they appear to contribute to two of the characteristic PDAC features: the massive fibrosis of the tumor stroma (desmoplasia) and the efficient immune evasion. Our critical review of the literature clearly shows that there is still a remarkable lack of knowledge with respect to the contribution of ion channels to these two typical PDAC properties. Yet, we can draw parallels from ion channel research in other fibrotic and inflammatory diseases. Evidence is accumulating that pancreatic stellate cells express the same "profibrotic" ion channels. Similarly, it is at least in part known which major ion channels are expressed in those innate and adaptive immune cells that populate the PDAC microenvironment. We explore potential therapeutic avenues derived thereof. Since drugs targeting PDAC-relevant ion channels are already in clinical use, we propose to repurpose those in PDAC. The quest for ion channel targets is both motivated and complicated by the fact that some of the relevant channels, for example, KCa3.1, are functionally expressed in the cancer, stroma, and immune cells. Only in vivo studies will reveal which arm of the balance we should put our weights on when developing channel-targeting PDAC therapies. The time is up to explore the efficacy of ion channel targeting in (transgenic) murine PDAC models before launching clinical trials with repurposed drugs.

TRPV4 integrates matrix mechanosensing with Ca2+ signaling to regulate extracellular matrix remodeling

In healthy connective tissues, mechanosensors trigger the generation of Ca²⁺ signals, which enable cells to maintain the structure of the fibrillar collagen matrix through actomyosin contractile forces. Transient receptor potential vanilloid type 4 (TRPV4) is a mechanosensitive Ca²⁺ -permeable channel that, when expressed in cell-matrix adhesions of the plasma membrane, regulates extracellular matrix (ECM) remodeling. In high prevalence disorders such as fibrosis and tumor metastasis, dysregulated matrix remodeling is associated with disruptions of Ca²⁺ homeostasis and TRPV4 function. Here, we consider that ECM polymers transmit cell-activating mechanical signals to TRPV4 in cell adhesions. When activated, TRPV4 regulates fibrillar collagen remodeling, thereby altering the mechanical properties of the ECM. In this review, we integrate functionally connected processes of matrix remodeling to highlight how TRPV4 in cell adhesions and matrix mechanics are reciprocally regulated through Ca²⁺ signaling.

Polydatin inhibits ZEB1-invoked epithelial-mesenchymal transition in fructose-induced liver fibrosis

High fructose intake is a risk factor for liver fibrosis. Polydatin is a main constituent of the rhizome of Polygonum cuspidatum, which has been used in traditional Chinese medicine to treat liver fibrosis. However, the underlying mechanisms of fructose-driven liver fibrosis as well as the actions of polydatin are not fully understood. In this study, fructose was found to promote zinc finger E-box binding homeobox 1 (ZEB1) nuclear translocation, decrease microRNA-203 (miR-203) expression, increase survivin, activate transforming growth factor β1 (TGF-β1)/Smad signalling, down-regulate E-cadherin, and up-regulate fibroblast specific protein 1 (FSP1), vimentin, N-cadherin and collagen I (COL1A1) in rat livers and BRL-3A cells, in parallel with fructose-induced liver fibrosis. Furthermore, ZEB1 nuclear translocation-mediated miR-203 low-expression was found to target survivin to activate TGF-β1/Smad signalling, causing the EMT in fructose-exposed BRL-3A cells. Polydatin antagonized ZEB1 nuclear translocation to up-regulate miR-203, subsequently blocked survivin-activated TGF-β1/Smad signalling, which were consistent with its protection against fructose-induced EMT and liver fibrosis. These results suggest that ZEB1 nuclear translocation may play an essential role in fructose-induced EMT in liver fibrosis by targeting survivin to activate TGF-β1/Smad signalling. The suppression of ZEB1 nuclear translocation by polydatin may be a novel strategy for attenuating the EMT in liver fibrosis associated with high fructose diet.

Pharmacological Inhibition of Transient Receptor Potential Vanilloid 4 (TRPV4) Channel Alleviates Carbon Tetrachloride-Induced Liver Fibrosis in Mice

BACKGROUND

Transient receptor potential vanilloid 4 (TRPV4) is a member of the TRP channel family and is involved in diverse physiological and pathological processes. Accumulating evidence from in vitro studies indicates that TRPV4 has a potential role in liver fibrosis, but its precise role in the pathophysiological development of this condition is unclear. Exogenous interventions and endogenous reactions should be considered.

METHODS

This study used a mouse model of carbon tetrachloride (CCl4)-induced liver fibrosis to investigate the effects of intraperitoneal injection of the novel TRPV4 channel selective agonist GSK1016790A (GSK) and antagonist HC-067047 (HC).

RESULTS

As compared with the CCl4 group, collagen fiber deposition and alpha-smooth muscle actin (α-SMA) levels were markedly higher and hepatic lobule disorganization was worse in the CCl4+GSK group, while collagen fiber deposition was significantly lower and hepatic lobule disorganization was less severe in the CCl4+HC group.

CONCLUSIONS

The present findings suggest that activation of TRPV4 channels worsens liver fibrosis and that inhibition of TRPV4 channels may alleviate liver fibrosis in vivo.

Ca2+ signalling in fibroblasts and the therapeutic potential of KCa3.1 channel blockers in fibrotic diseases

The role of Ca²⁺ signalling in fibroblasts is of great interest in fibrosis-related diseases. Intracellular free Ca²⁺ ([Ca²⁺ ]_i ) is a ubiquitous secondary messenger, regulating a number of cellular functions such as secretion, metabolism, differentiation, proliferation and contraction. The intermediate conductance Ca²⁺ -activated K⁺ channel K_Ca 3.1 is pivotal in Ca²⁺ signalling and plays a central role in fibroblast processes including cell activation, migration and proliferation through the regulation of cell membrane potential. Evidence from a number of approaches demonstrates that K_Ca 3.1 plays an important role in the development of many fibrotic diseases, including idiopathic pulmonary, renal tubulointerstitial fibrosis and cardiovascular disease. The K_Ca 3.1 selective blocker senicapoc was well tolerated in clinical trials for sickle cell disease, raising the possibility of rapid translation to the clinic for people suffering from pathological fibrosis. This review after analysing all the data, concludes that targeting K_Ca 3.1 should be a high priority for human fibrotic disease.

Extracellular Vesicles From Pathological Microenvironment Induce Endothelial Cell Transformation and Abnormal Angiogenesis via Modulation of TRPV4 Channels

The soluble and mechanical microenvironment surrounding endothelial cells influences and instructs them to form new blood vessels. The cells in the pathological tumor microenvironment release extracellular vesicles (EVs) for paracrine signaling. EVs have been shown to induce angiogenesis by communicating with endothelial cells, but the underlying molecular mechanisms are not well known. We have recently shown that the mechanosensitive ion channel transient receptor vanilloid 4 (TRPV4) expression and activity is significantly reduced in tumor endothelial cells (TEC), and that activation of TRPV4 normalized the tumor vasculature and improved cancer therapy. However, whether and how the tumor microenvironment downregulates TRPV4 and transforms the normal endothelial cell phenotype remains unknown. To explore this, we exposed normal human endothelial cells (hNEC) to human lung tumor cell conditioned media (TCM) and measured phenotypic changes and angiogenesis. We found that treatment with TCM transformed hNEC to a TEC-like phenotype (hTEC) as evidenced by increased expression of tumor endothelial cell marker 8 (TEM8) and exhibition of abnormal angiogenesis on 2D-Matrigels compared to normal hNEC. Mechanistically, expression and activity of TRPV4 was decreased in hTEC. Further, when pre-treated with exosome inhibitor GW4869, TCM failed to induce hNEC transformation to hTEC. Finally, addition of purified EVs from TCM induced transformation of hNEC to hTEC as evidenced by abnormal angiogenesis in vitro. Taken together, our results suggest that the pathological (tumor) microenvironment transforms normal endothelial cells into a tumor endothelial cell-like phenotype through EVs via the downregulation of TRPV4.

Transient receptor potential ion-channel subfamily V member 4: a potential target for cancer treatment

The transient receptor potential ion-channel superfamily consists of nonselective cation channels located mostly on the plasma membranes of numerous animal cell types, which are closely related to sensory information transmission (e.g., vision, pain, and temperature perception), as well as regulation of intracellular Ca2+ balance and physiological activities of growth and development. Transient receptor potential ion channel subfamily V (TRPV) is one of the largest and most diverse subfamilies, including TRPV1-TRPV6 involved in the regulation of a variety of cellular functions. TRPV4 can be activated by various physical and chemical stimuli, such as heat, mechanical force, and phorbol ester derivatives participating in the maintenance of normal cellular functions. In recent years, the roles of TRPV4 in cell proliferation, differentiation, apoptosis, and migration have been extensively studied. Its abnormal expression has also been closely related to the onset and progression of multiple tumors, so TRPV4 may be a target for cancer diagnosis and treatment. In this review, we focused on the latest studies concerning the role of TRPV4 in tumorigenesis and the therapeutic potential. As evidenced by the effects on cancerogenesis, TRPV4 is a potential target for anticancer therapy.

CXCR4-targeted liposomal mediated co-delivery of pirfenidone and AMD3100 for the treatment of TGFβ-induced HSC-T6 cells activation

Background: Liver fibrosis is a chronic liver disease associated with an excessive accumulation of extracellualr matrix (ECM) proteins which ultimately lead to cirrohosis and hepatocellular carcinoma.

Purpose: Liver fibrosis therapies that use combination approaches with the ability to affect multiple disease pathways have proven higher efficacies. This study aimed at optimizing and characterizing the co-encapsulation of pirfenidone (PF) and AMD3100 (AMD) into CXCR4-targeted combination liposomes (CTC liposome) for CXCR4 targeting, and the inhibition of major molecular culprits ie α-SMA, CXCR4, TGFβ, and P-p38 involved in liver fibrosis in-vitro.

Methods: The CTC liposomes were prepared using the thin-film hydration method. The concentration of encapsulated AMD and PF was measured by HPLC and UV spectrophotometry, respectively. Tramsmission electron microscopy (TEM) was used to determine the liposomal morphology. The CXCR4 targeting ability was determined by CXCR4 redistribution assay. Confocal microscopy and flowcytometry were used to determine the CXCR4 mediated cell uptake. The apoptosis inducing and protein downreguating ability of CTC liposomes were determined by apoptosis assay and western blot analysis, respectively. In-vivo biodistribution and Hoechst staining were used to confirm the feasibility of CTC liposome for the in-vivo applications and drug targeted accumulation, respectively.

Results: The TEM studies revealed that CTC liposomes were spherical in shape. The cumulative release of AMD and PF from CTC liposome was 67% and 84%, respectively, at 48 h. Compared to the free drug counterparts, encapsulated drugs displayed higher cell viability. The CXCR4 redistribution assay confirmed the CXCR4 targeting and antagonistic ability of CTC liposomes. The CTC liposomes were internalized more effectively via caveolae-mediated endocytic pathways. CTC liposomes displayed aggressive apoptosis (87.3%) in TGFβ-induced activated HSC-T6 cells suggesting a propensity to fibrosis regression. Also, CTC liposomes significantly reduced α-SMA (65%), CXCR4 (77%), TGFβ (89%), and P-p38 (66%) expressions, better than free drugs. CTC@IR780 liposomes (CTC liposomes incorporating IR780 dye) were more accumulated in fibrotic livers compared to free IR780, as judged by in-vivo imaging, biodistribution analysis, and Hoechst staining. These findings suggest that this simple and stable CTC liposomal system holds a great promise for the treatment and prevention of liver fibrosis.

PI3-kinase/Akt pathway-regulated membrane transportation of acid-sensing ion channel 1a/Calcium ion influx/endoplasmic reticulum stress activation on PDGF-induced HSC Activation

Acid-sensing ion channel 1a (ASIC1a) allows Na⁺ and Ca²⁺ flow into cells. It is expressed during inflammation, in tumour and ischaemic tissue, in the central nervous system and non-neuronal injury environments. Endoplasmic reticulum stress (ERS) is caused by the accumulation of misfolded proteins that interferes with intracellular calcium homoeostasis. Our recent reports showed ASIC1a and ERS are involved in liver fibrosis progression, particularly in hepatic stellate cell (HSC) activation. In this study, we investigated the roles of ASIC1a and ERS in activated HSC. We found that ASIC1a and ERS-related proteins were up-regulated in carbon tetrachloride (CCl₄ )-induced fibrotic mouse liver tissues, and in patient liver tissues with hepatocellular carcinoma with severe liver fibrosis. The results show silencing ASIC1a reduced the expression of ERS-related biomarkers GRP78, Caspase12 and IREI-XBP1. And, ERS inhibition by 4-PBA down-regulated the high expression of ASIC1a induced by PDGF, suggesting an interactive relationship. In PDGF-induced HSCs, ASIC1a was activated and migrated to the cell membrane, leading to extracellular calcium influx and ERS, which was mediated by PI3K/AKT pathway. Our work shows PDGF-activated ASIC1a via the PI3K/AKT pathway, induced ERS and promoted liver fibrosis progression.

Expression of trpv channels during Xenopus laevis embryogenesis

Transient receptor potential (TRP) cation channel genes code for an extensive family of conserved proteins responsible for a variety of physiological processes, including sensory perception, ion homeostasis, and chemical signal transduction. The TRP superfamily consists of seven subgroups, one of which is the transient receptor potential vanilloid (trpv) channel family. While trpv channels are relatively well studied in adult vertebrate organisms given their role in functions such as nociception, thermoregulation, and osmotic regulation in mature tissues and organ systems, relatively little is known regarding their function during embryonic development. Although there are some reports of the expression of specific trpv channels at particular stages in various organisms, there is currently no comprehensive analysis of trpv channels during embryogenesis. Here, performing in situ hybridization, we examined the spatiotemporal expression of trpv channel mRNA during early Xenopus laevis embryogenesis. Trpv channels exhibited unique patterns of embryonic expression at distinct locations including the trigeminal ganglia, spinal cord, cement gland, otic vesicle, optic vesicle, nasal placode, notochord, tailbud, proctodeum, branchial arches, epithelium, somite and the animal pole during early development. We have also observed the colocalization of trpv channels at the animal pole (trpv 2/4), trigeminal ganglia (trpv 1/2), and epithelium (trpv 5/6). These localization patterns suggest that trpv channels may play diverse roles during early embryonic development.

miR-203 Inhibits Alcohol-Induced Hepatic Steatosis by Targeting Lipin1

Alcoholic liver disease (ALD) is a global liver disease which characterized by liver inflammation, fatty liver, alcoholic hepatitis, or liver cirrhosis. Alcohol abuse is one of the main reasons for liver disease. Alcoholic fatty liver (AFL) disease is the early stage of ALD and associated with the excessive lipids accumulation in hepatocytes as well as oxidative stress. MicroRNA-203 (miR-203) is known to suppress the proliferation and metastasis of hepatocellular carcinoma, but the role in the progression of alcoholic liver disease is not clear and is warranted for further investigation. In the present study, we have found the expression of miR-203 is down-regulated in Gao-Binge alcoholic mice model and ethanol-induced AML-12 cell lines in vitro. Furthermore, over-expression of miR-203 decrease the lipids accumulation in liver and ethanol-induced AML-12 cells. Mechanistically, we identified that Lipin1 is a key regulator of hepatic lipid metabolism, and acts as a downstream target for miR-203. In summary, our results suggested that over-expression of miR-203 inhibited the liver lipids accumulation and the progression of AFL by targeting Lipin1.

NPPB modulates apoptosis, proliferation, migration and extracellular matrix synthesis of conjunctival fibroblasts by inhibiting PI3K/AKT signaling

When treating glaucoma, excessive scar tissue reactions reduce the postoperative survival rate of the filtering bleb. Accumulating evidence has demonstrated that the proliferation, migration and extracellular matrix (ECM) synthesis of fibroblasts are important molecular mechanisms underlying scar formation. Recent evidence has demonstrated that chloride channels play an important role in controlling cell proliferation, apoptosis, migration and the cell cycle process in several cell types, but the effects of chloride channels on conjunctival fibroblasts have not be studied. The aim of the present study was to investigate the effects of the chloride channel blocker 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) on cell proliferation, apoptosis, migration, cell cycle progression and ECM synthesis in human conjunctival fibroblasts (HConFs), and to further investigate the mechanism of resistance to scar formation following glaucoma filtration surgery. HConFs were exposed to NPPB or lubiprostone. Cell proliferation and viability was evaluated using the Cell Counting Kit-8. Cell migration was measured using Transwell migration and scratch‑wound assays. Flow cytometry was used to study apoptosis and cell cycle progression. Quantitative polymerase chain reaction and western blot analyses were performed to determine mRNA and protein expression levels, respectively. Following NPPB treatment, HConFs exhibited reduced proliferation and migration, along with increased apoptosis. NPPB also inhibited cell cycle progression by arresting cells in the G0̸G1 phase and reducing collagen I and fibronectin expression, as well as the phosphorylation of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT). However, lubiprostone treatment exerted the opposite effects on HConFs. Therefore, NPPB treatment inhibited proliferation, migration, cell cycle progression and synthesis of the ECM, while promoting apoptosis in HConFs, by inhibiting the PI3K̸AKT signaling pathway.

Serum microRNAs as predictors for liver fibrosis staging in hepatitis C virus-associated chronic liver disease patients

Accurate staging of liver fibrosis is important for clinical decision making and personalized management. Liver fibrosis is influenced by patients' genomics, including IFNL3 genotype and microRNA expression. However, incorporating microRNAs into fibrosis prediction algorithms has not been investigated. We examined the potential of eight selected serum microRNAs; miR-122, miR-126, miR-129, miR-199a, miR-155, miR-203a, miR-221, and miR-223 as non-invasive biomarkers to stage liver fibrosis in HCV-associated chronic liver disease (HCV-CLD). 145 Egyptian HCV-CLD patients were divided according to Metavir fibrosis scores. MicroRNAs and IFNL3 rs12979860 genotype were assayed by RT-qPCR and allelic discrimination techniques, respectively. Serum miR-122 was downregulated, whereas miR-203a and miR-223 were upregulated in significant fibrosis (≥F2) compared with no/mild fibrosis (F0-F1). Serum miR-126, miR-129, miR-203a, and miR-223 were upregulated in severe fibrosis (≥F3) and cirrhosis (F4) compared with F0-F2 and F0-F3, respectively. miR-221 was upregulated in ≥F3, but unchanged in F4. miR-155, miR-199a, and IFNL3 rs12979860 genotype were not significantly different in all comparisons. Differentially expressed serum microRNAs discriminated ≥F2, ≥F3, and F4 by receiver-operating-characteristic analysis. Multivariate logistic analysis revealed a model combining miR-129, miR-223, AST, and platelet count with high diagnostic accuracy for ≥F3 (AUC=0.91). The model also discriminated F4 (AUC=0.96) and ≥F2 (AUC=0.783), and was superior to APRI and FIB-4 in discriminating ≥F3 and F4, but not ≥F2. In conclusion, combining serum microRNAs with baseline predictors could serve as a new non-invasive algorithm for staging HCV-associated liver fibrosis. Additional studies are required to confirm this model and test its significance in liver fibrosis of other etiologies.

miR‑203 inhibits the expression of collagen‑related genes and the proliferation of hepatic stellate cells through a SMAD3‑dependent mechanism

Activation of hepatic stellate cells (HSCs) is a pivotal event during hepatic fibrogenesis. Activated HSCs are the main source of collagen and other extracellular matrix (ECM) components, and emerging antifibrotic therapies are aimed at preventing ECM synthesis and deposition. MicroRNAs (miRNAs) have been demonstrated to exert regulatory effects on HSC activation and ECM synthesis. In the present study, the HSC-T6 rat hepatic stellate cell line was transiently transfected with a miRNA (miR)-203 mimic, which is an artificial miRNA that enhances the function of miR-203, with a miR-203 inhibitor or with a scramble miRNA negative control. mRNA and protein expression levels of collagen (COL) 1A1, COL3A1, α-smooth muscle actin (α-SMA) and mothers against decapentaplegic homolog 3 (SMAD3) were assessed using reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. The interaction between miR-203 and the 3′-untranslated region (UTR) of SMAD3 mRNA was examined using a dual-luciferase reporter assay. The proliferative capabilities of activated HSCs were measured using an MTT assay. The present results demonstrated that the mRNA and protein expression levels of COL1A1, COL3A1, α-SMA and SMAD3 were significantly upregulated following transfection of HSC-T6 cells with the miR-203 inhibitor. Conversely, COL1A1, COL3A1, α-SMA, and SMAD3 mRNA and protein expression appeared to be downregulated in rat HSCs transfected with miR-203 mimics. Notably, the inhibition of miR-203 expression was revealed to promote HSC proliferation, whereas increased miR-203 expression suppressed the proliferative capabilities of HSC-T6 cells. Furthermore, SMAD3 was revealed to be a direct target of miR-203. The present study suggested that miR-203 may function to prevent the synthesis and deposition of ECM components, including COL1A1, COL3A1 and α-SMA, and to inhibit the proliferation of HSCs through a SMAD3-dependent mechanism. Therefore, it may be hypothesized that miR-203 has potential as a novel target for the development of alternative therapeutic strategies for the treatment of patients with hepatic fibrosis in clinical practice.

TRPV4: Molecular Conductor of a Diverse Orchestra

Transient receptor potential vanilloid type 4 (TRPV4) is a calcium-permeable nonselective cation channel, originally described in 2000 by research teams led by Schultz (Nat Cell Biol 2: 695-702, 2000) and Liedtke (Cell 103: 525-535, 2000). TRPV4 is now recognized as being a polymodal ionotropic receptor that is activated by a disparate array of stimuli, ranging from hypotonicity to heat and acidic pH. Importantly, this ion channel is constitutively expressed and capable of spontaneous activity in the absence of agonist stimulation, which suggests that it serves important physiological functions, as does its widespread dissemination throughout the body and its capacity to interact with other proteins. Not surprisingly, therefore, it has emerged more recently that TRPV4 fulfills a great number of important physiological roles and that various disease states are attributable to the absence, or abnormal functioning, of this ion channel. Here, we review the known characteristics of this ion channel's structure, localization and function, including its activators, and examine its functional importance in health and disease.

Coding and non-coding gene regulatory networks underlie the immune response in liver cirrhosis

Liver cirrhosis is recognized as being the consequence of immune-mediated hepatocyte damage and repair processes. However, the regulation of these immune responses underlying liver cirrhosis has not been elucidated. In this study, we used GEO datasets and bioinformatics methods to established coding and non-coding gene regulatory networks including transcription factor-/lncRNA-microRNA-mRNA, and competing endogenous RNA interaction networks. Our results identified 2224 mRNAs, 70 lncRNAs and 46 microRNAs were differentially expressed in liver cirrhosis. The transcription factor -/lncRNA- microRNA-mRNA network we uncovered that results in immune-mediated liver cirrhosis is comprised of 5 core microRNAs (e.g., miR-203; miR-219-5p), 3 transcription factors (i.e., FOXP3, ETS1 and FOS) and 7 lncRNAs (e.g., ENTS00000671336, ENST00000575137). The competing endogenous RNA interaction network we identified includes a complex immune response regulatory subnetwork that controls the entire liver cirrhosis network. Additionally, we found 10 overlapping GO terms shared by both liver cirrhosis and hepatocellular carcinoma including “immune response” as well. Interestingly, the overlapping differentially expressed genes in liver cirrhosis and hepatocellular carcinoma were enriched in immune response-related functional terms. In summary, a complex gene regulatory network underlying immune response processes may play an important role in the development and progression of liver cirrhosis, and its development into hepatocellular carcinoma.

MicroRNAs regulate hepatic fibrosis via TGF-β/Smad pathway

Studies have shown that transforming growth factor-β (TGF-β) is one of the most important factors to promote hepatic fibrosis (HF), and the TGF-β/Smad pathway is a major signaling pathway involved in HF. Abnormal expression of microRNAs (miRNAs) has a key role in the development of HF. In recent years, studies suggest that regulating miRNAs may affect the TGF-β/Smad pathway. This paper discusses the TGF-β/Smad pathway and the related miRNAs that are associated with HF.

TRPV4 activation of endothelial nitric oxide synthase resists nonalcoholic fatty liver disease by blocking CYP2E1-mediated redox toxicity

NAFLD is a clinically progressive disease with steatosis, inflammation, endothelial dysfunction and fibrosis being the stages where clinical intervention becomes necessary. Lack of early biomarkers and absence of a FDA approved drug obstructs efforts for effective treatment. NAFLD progression is strongly linked to a balance between liver injury, tissue regeneration and the functioning of endogenous defense mechanisms. The failure of the defense pathways to resist the tissue damage arising from redox stress, one of the "multiple hits" in disease progression, give rise to heightened inflammation and occasional fibrosis. We introduce an endogenous defense mechanism in the liver that is mediated by TRPV4, a transient receptor potential calcium-permeable ion channel that responds to the cytotoxic liver environment and negatively regulates CYP2E1, a cytochrome p450 enzyme. Using Trpv4-/- mice and cultured primary cells, we show that TRPV4 is activated both by damage associated molecular pattern HMGB1 and collagen in diseased Kupffer cells that in turn activate the endothelial NOS (NOS3) to release nitric oxide (NO). The diffusible NO acts in a paracrine fashion in neighboring hepatocytes to deactivate the redox toxicity induced by CYP2E1. We also find that CYP2E1-mediated TRPV4 repression in late stages causes an unrestricted progression of disease. Thus, TRPV4 functions as a sensor of cell stress in the diseased fatty liver and constitutes an endogenous defense molecule, a novel concept with potential for therapeutic approaches against NAFLD, perhaps also against hepatic drug toxicity in general.

Latest advances in understanding of relationship between microRNAs and hepatic fibrosis

Studies have shown the expression of microRNAs (miRNAs) in hepatic fibrosis. MiRNAs are important in regulating hepatic fibrosis, and have a close relationship with the occurrence, development, diagnosis and treatment of hepatic fibrosis. This article reviews the latest advances in the understanding of the relationship between miRNAs and hepatic fibrosis.

Role of TRPC1 channels in pressure-mediated activation of murine pancreatic stellate cells

The tumor environment contributes importantly to tumor cell behavior and cancer progression. Aside from biochemical constituents, physical factors of the environment also influence the tumor. Growing evidence suggests that mechanics [e.g., tumor (stroma) elasticity, tissue pressure] are critical players of cancer progression. Underlying mechanobiological mechanisms involve among others the regulation of focal adhesion molecules, cytoskeletal modifications, and mechanosensitive (MS) ion channels of cancer- and tumor-associated cells. After reviewing the current concepts of cancer mechanobiology, we will focus on the canonical transient receptor potential 1 (TRPC1) channel and its role in mechano-signaling in tumor-associated pancreatic stellate cells (PSCs). PSCs are key players of pancreatic fibrosis, especially in cases of pancreatic ductal adenocarcinoma (PDAC). PDAC is characterized by the formation of a dense fibrotic stroma (desmoplasia), primarily formed by activated PSCs. Desmoplasia contributes to high pancreatic tissue pressure, which in turn activates PSCs, thereby perpetuating matrix deposition. Here, we investigated the role of the putatively mechanosensitive TRPC1 channels in murine PSCs exposed to elevated ambient pressure. Pressurization leads to inhibition of mRNA expression of MS ion channels. Migration of PSCs representing a readout of their activation is enhanced in pressurized PSCs. Knockout of TRPC1 leads to an attenuated phenotype. While TRPC1-mediated calcium influx is increased in wild-type PSCs after pressure incubation, loss of TRPC1 abolishes this effect. Our findings provide mechanistic insight how pressure, an important factor of the PDAC environment, contributes to PSC activation. TRPC1-mediated activation could be a potential target to disrupt the positive feedback of PSC activation and PDAC progression.

Activation of Transient Receptor Potential Vanilloid 4 Promotes the Proliferation of Stem Cells in the Adult Hippocampal Dentate Gyrus

Neurogenesis plays an important role in adult hippocampal function, and this process can be modulated by intracellular calcium. The activation of transient receptor potential vanilloid 4 (TRPV4) induces an increase in intracellular calcium concentration, but whether neurogenesis can be modulated by TRPV4 activation remains unclear. Here, we report that intracerebroventricular injection of the TRPV4 agonist GSK1016790A for 5 days enhanced the proliferation of stem cells in the hippocampal dentate gyrus (DG) of adult mice without affecting neurite growth, differentiation, or survival of newborn cells. GSK1016790A induced increases in the hippocampal protein levels of cyclin-dependent kinase (CDK) 6, CDK2, cyclin E1, and cyclin A2 but did not affect CDK4 and cyclin D1 expression. The phosphorylation of retinoblastoma protein (Rb) in hippocampi was enhanced in GSK1016790A-injected mice compared with control mice. Moreover, hippocampal protein levels of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation were enhanced by GSK1016790A. Finally, GSK1016790A-enhanced proliferation was markedly blocked by a MAPK/ERK kinase or p38 MAPK antagonist (U0126 or SB203580, respectively). The increased protein levels of CDK2 and CDK6, as well as those of cyclin E1 and cyclin A2, in GSK1016790A-injected mice were substantially reduced by co-injection of U0126 or SB203580. We conclude that TRPV4 activation results in the proliferation of stem cells in the adult hippocampal DG, which is likely mediated through ERK1/2 and p38 MAPK signaling to increase the expression of CDKs (CDK6 and CDK2) and cyclins (cyclin E1 and A2), phosphorylate Rb consequently, and accelerate the cell cycle ultimately.

Ion Channels and Oxidative Stress as a Potential Link for the Diagnosis or Treatment of Liver Diseases

Oxidative stress results from a disturbed balance between oxidation and antioxidant systems. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) may be either harmful or beneficial to the cells. Ion channels are transmembrane proteins that participate in a large variety of cellular functions and have been implicated in the development of a variety of diseases. A significant amount of the available drugs in the market targets ion channels. These proteins have sulfhydryl groups of cysteine and methionine residues in their structure that can be targeted by ROS and RNS altering channel function including gating and conducting properties, as well as the corresponding signaling pathways associated. The regulation of ion channels by ROS has been suggested to be associated with some pathological conditions including liver diseases. This review focuses on understanding the role and the potential association of ion channels and oxidative stress in liver diseases including fibrosis, alcoholic liver disease, and cancer. The potential association between ion channels and oxidative stress conditions could be used to develop new treatments for major liver diseases.

Mechanical control of cardiac myofibroblasts

Fibroblasts produce and turn over collagenous extracellular matrix as part of the normal adaptive response to increased mechanical load in the heart, e.g. during prolonged exercise. However, chronic overload as a consequence of hypertension or myocardial injury trigger a repair program that culminates in the formation of myofibroblasts. Myofibroblasts are opportunistically activated from various precursor cells that all acquire a phenotype promoting excessive collagen secretion and contraction of the neo-matrix into stiff scar tissue. Stiff fibrotic tissue reduces heart distensibility, impedes pumping and valve function, contributes to diastolic and systolic dysfunction, and affects myocardial electrical transmission, potentially leading to arrhythmia and heart failure. Here, we discuss how mechanical factors, such as matrix stiffness and strain, are feeding back and cooperate with cytokine signals to drive myofibroblast activation. We elaborate on the importance of considering the mechanical boundary conditions in the heart to generate better cell culture models for mechanistic studies of cardiac fibroblast function. Elements of the force transmission and mechanoperception apparatus acting in myofibroblasts are presented as potential therapeutic targets to treat fibrosis.

TRPV4 channels: physiological and pathological role in cardiovascular system

TRPV4 channels are non-selective cation channels permeable to Ca(2+), Na(+), and Mg(2+) ions. Recently, TRPV4 channels have received considerable attention as these channels are widely expressed in the cardiovascular system including endothelial cells, cardiac fibroblasts, vascular smooth muscles, and peri-vascular nerves. Therefore, these channels possibly play a pivotal role in the maintenance of cardiovascular homeostasis. TRPV4 channels critically regulate flow-induced arteriogenesis, TGF-β1-induced differentiation of cardiac fibroblasts into myofibroblasts, and heart failure-induced pulmonary edema. These channels also mediate hypoxia-induced increase in proliferation and migration of pulmonary artery smooth muscle cells and progression of pulmonary hypertension. These channels also maintain flow-induced vasodilation and preserve vascular function by directly activating Ca(2+)-dependent KCa channels. Furthermore, these may also induce vasodilation and maintain blood pressure indirectly by evoking the release of NO, CGRP, and substance P. The present review discusses the evidences and the potential mechanisms implicated in diverse responses including arteriogenesis, cardiac remodeling, congestive heart failure-induced pulmonary edema, pulmonary hypertension, flow-induced dilation, regulation of blood pressure, and hypoxic preconditioning.

Impact of upregulation of miR-203 on cell proliferation and collagen synthesis in hepatic stellate cells

AIM: To investigate the impact of upregulation of miR-203 on cell proliferation and collagen synthesis in hepatic stellate cells.

METHODS: HSC-T6 cells were transfected with miR-203 mimic using Lipofectamine™ 2000, and propagated for 48 h. Total proteins and total RNAs were extracted from these cells. The mRNA and protein expression of α-smooth muscle actin (α-SMA), type Ⅰ collagen and type Ⅲ collagen was measured by RT-qPCR and Western blot, respectively. The proliferation of HSC-T6 cells was assessed using MTT assay.

RESULTS: Compared with the negative control group, α-SMA protein and mRNA expression in the miR-203 mimic group decreased by 75% and 80%, respectively (P < 0.01); type Ⅰ collagen protein and mRNA expression decreased by 56% (P < 0.01) and 48% (P < 0.05), respectively; type Ⅲ collagen protein and mRNA expression decreased 45% and 60%, respectively (P < 0.05); cellular proliferative activity decreased by 20% ± 5% (P < 0.01).

CONCLUSION: Upregulation of miR-203 can significantly inhibit cell proliferation and collagen synthesis in hepatic stellate cells.

CTGF siRNA ameliorates tubular cell apoptosis and tubulointerstitial fibrosis in obstructed mouse kidneys in a Sirt1-independent manner

Transforming growth factor-β1 (TGF-β1) plays an important role in the pathogenesis and progression of chronic kidney disease. Connective tissue growth factor (CTGF) is a critical fibrogenic mediator of TGF-β1. Mammalian sirtuin 1 (Sirt1) is reported to attenuate renal fibrosis by inhibiting the TGF-β1 pathway. This study was designed to detect whether the delivery of CTGF siRNA in vivo directly ameliorates renal fibrosis. Furthermore, the relationship with Sirt1 underlying the protective effect of CTGF siRNA on interstitial fibrosis and apoptosis was explored. Here, we report that the expressions of CTGF and TGF-β1 were increased while Sirt1 expression and activity were both dramatically decreased in mouse kidneys with unilateral ureteral obstruction. Recombinant human TGF-β1 treatment in HK-2 cells increased CTGF levels and remarkably decreased Sirt1 levels and was accompanied by apoptosis and release of fibrosis-related factors. Recombinant human CTGF stimulation also directly induced apoptosis and fibrosis. The CTGF siRNA plasmid ameliorated tubular cell apoptosis and tubulointerstitial fibrosis, but did not affect Sirt1 expression and activity both in vivo and in vitro. Furthermore, overexpression of Sirt1 abolished TGF-β1-induced cell apoptosis and fibrosis, while Sirt1 overexpression suppressed CTGF expression via stimulation by TGF-β1. This study provides evidence that treatment strategies involving the delivery of siRNA targeting potentially therapeutic transgenes may be efficacious. Our results suggest that the decrease in Sirt1 is associated with the upregulated expression of CTGF in renal fibrosis, and may aid in the design of new therapies for the prevention of renal fibrosis.

Myofibroblasts

Myofibroblasts are activated in response to tissue injury with the primary task to repair lost or damaged extracellular matrix. Enhanced collagen secretion and subsequent contraction - scarring - are part of the normal wound healing response and crucial to restore tissue integrity. Due to myofibroblasts ability to repair but not regenerate, accumulation of scar tissue is always associated with reduced organ performance. This is a fair price to pay by the body for not falling apart. Whereas myofibroblasts typically vanish after successful repair, dysregulation of the normal repair process can lead to persistent myofibroblast activation, for instance by chronic inflammation or mechanical stress in the tissue. Excessive repair leads to the accumulation of stiff collagenous ECM contractures - fibrosis - with dramatic consequences for organ function. The clinical need to terminate detrimental myofibroblast activities has stimulated researchers to answer a number of essential questions: where do myofibroblasts come from, what are the factors leading to their activation, how do we discriminate myofibroblasts from other cells, what is the molecular basis for their contractile activity, and how can we stop or at least control them? This article reviews the current state of the myofibroblast literature by emphasizing their role in ocular repair and fibrosis. It appears that although the eye is quite an extraordinary organ, ocular myofibroblasts behave or misbehave just like their siblings in other organs.

Novel insights into TRPM7 function in fibrotic diseases: a potential therapeutic target

"Transient receptor potential (TRP) channels are cellular sensors for a wide spectrum of physical and chemical stimuli. Activation of TRP channels changes the membrane potential, translocates important signaling ions crossing the cell membrane, alters enzymatic activity, and initiates endocytosis/exocytosis (Zheng, 2013)." Fibrosis is the leading cause of organ dysfunction in diseases, which is characterized by an imbalance in the turnover of extracellular matrix components. Accumulating evidence has demonstrated that TRPM7, a member of TRP channels superfamily, participates in the development and pathogenesis of fibrotic diseases, such as hepatic, pulmonary and cardiac fibrosis. In this review, we discuss the comprehensive role of TRPM7 in modulating profibrotic response and its potential as therapeutic target for fibrotic diseases.

Transient receptor potential vanilloid 4 inhibits rat HSC-T6 apoptosis through induction of autophagy

Hepatic stellate cell (HSC) activation is a significant event in the development of liver fibrosis. Promoting the activated HSCs apoptosis contributes to the reversal of liver fibrosis. Autophagy is considered to be critical for many cellular and pathological processes including liver fibrosis. Transient receptor potential vanilloid 4 (TRPV4), another member of the transient receptor potential (TRP) channel, is proved to be a vital modulator in regulating HSC proliferation during liver fibrosis. However, the precise mechanism of TRPV4 on HSC apoptosis is still unclear. Here, we explored the role of TRPV4 in regulating HSC-T6 cell apoptosis. Our study detected that the expressions of TRPV4 mRNA and protein were dramatically increased in HSC-T6 in response to TGF-β1 stimulation by qRT-PCR and Western blot. Moreover, the HSC-T6 transfected with si-TRPV4 increased apoptosis and inhibited autophagy. In addition, the HSC-T6 treated with 4α-phorbol 12,13-didecanoate results in suppression of apoptosis and increase of autophagy. Furthermore, we indicated that TRPV4 induces autophagy by regulating AKT signaling pathway. In addition, we found that blockade of autophagy by chemical antagonists chloroquine (CQ) leads to increased apoptosis. Furthermore, blocking autophagy by CQ did not lead to a distinct change with or without TRPV4 over-expression. These results indicated that TRPV4 could inhibit HSCs apoptosis partially by regulating autophagy-dependent AKT signaling pathway activation.