TRPC1 contributes to endotoxemia-induced myocardial dysfunction via mediating myocardial apoptosis and autophagy.

Cardiac dysfunction is a vital complication of endotoxemia (ETM) with limited therapeutic options. Transient receptor potential canonical channel (TRPC)1 was involved in various heart diseases. While, the role of TRPC1 in ETM-induced cardiac dysfunction remains to be defined. In this study, we found that TRPC1 protein expression was significantly upregulated in hearts of lipopolysaccharide (LPS)-challenged mice. What's more, TRPC1 knockdown significantly alleviated LPS-induced cardiac dysfunction and injury. Further myocardial mRNA-sequencing analysis revealed that TRPC1 might participate in pathogenesis of ETM-induced cardiac dysfunction via mediating myocardial apoptosis and autophagy. Data showed that knockdown of TRPC1 significantly ameliorated LPS-induced myocardial apoptotic injury, cardiomyocytes autophagosome accumulation, and myocardial autophagic flux. Simultaneously, deletion of TRPC1 reversed LPS-induced molecular changes of apoptosis/autophagy signaling pathway in cardiomyocytes. Moreover, TRPC1 could promote LPS-triggered intracellular Ca2+ release, subsequent calpain activation and caveolin-1 degradation. Either blocking calpain by PD150606 or enhancing the amount of caveolin-1 scaffolding domain that interacts with TRPC1 by cell-permeable peptide cavtratin significantly alleviated the LPS-induced cardiac dysfunction and cardiomyocytes apoptosis/autophagy. Furthermore, cavtratin could inhibit LPS-induced calpain activation in cardiomyocytes. caveolin-1 could directly interact with calpain 2 both in vivo and in vitro. Importantly, cecal ligation and puncture-stimulated cardiac dysfunction and mortality were significantly alleviated in Trpc1-/- and cavtratin-treated mice, which further validated the contribution of TRPC1-caveolin-1 signaling axis in sepsis-induced pathological process. Overall, this study indicated that TRPC1 could promote LPS-triggered intracellular Ca2+ release, mediate caveolin-1 reduction, and in turn activates calpain to regulate myocardial apoptosis and autophagy, contributing to ETM-induced cardiac dysfunction of mice.

Activation of Paraventricular Melatonin Receptor 2 Mediates Melatonin-Conferred Cardioprotection Against Myocardial Ischemia/Reperfusion Injury.

Previous studies have shown that melatonin (Mel) can effectively ameliorate myocardial ischemia/reperfusion (MI/R) injury, but the mechanism is yet to be fully elucidated. Mel receptors are expressed in the paraventricular nucleus (PVN), which is also involved in regulating cardiac sympathetic nerve activity. The aim of this study was to examine whether Mel receptors in the PVN are involved in the protective effects of Mel against MI/R injury. The results of quantitative polymerase chain reaction, western blot, and immunofluorescence assays indicated that Mel receptor 2 (MT2) expression in the PVN was upregulated after MI/R. Intraperitoneal administration of Mel significantly improved post-MI/R cardiac function and reduced the infarct size, whereas shRNA silencing of MT2 in the PVN partially blocked this effect. Intraperitoneal administration of Mel reduced sympathetic nerve overexcitation caused by MI/R, whereas shRNA silencing of MT2 in the PVN partially diminished this effect. Furthermore, enzyme-linked immunosorbent assay and western blot results indicated that intraperitoneal administration of Mel lowered the levels of inflammatory cytokines in the PVN after MI/R injury, whereas the application of sh-MT2 in the PVN reduced this effect of Mel. Mel significantly reduced the levels of NF-κB after astrocyte oxygen and glucose deprivation/reoxygenation injury, and this effect was offset when MT2 was silenced. The above experimental results suggest that MT2 in the PVN partially mediated the protective effects of Mel against MI/R injury, and its underlying mechanisms may be related to postactivation amelioration of PVN inflammation and reduction of cardiac sympathetic nerve overexcitation.

Inhibition of RhoA/ROCK signaling pathway ameliorates hypoxic pulmonary hypertension via HIF-1α-dependent functional TRPC channels.

Hypoxic pulmonary vasoconstriction (HPV) can be modulated by Rho/Rho kinase signaling, which can alter HPV vascular function via regulating myosin light chain phosphorylation, in a manner generally believed to be Ca2+-independent. We hypothesized that the RhoA/ROCK signaling pathway also can regulate HPV vascular function via a Ca2+-dependent mechanism, signaling through the functional transient receptor potential canonical (TRPC) channels. In this study, male BALB/c mice were exposed to normoxic or 10% oxygen (hypoxic) conditions for six weeks, after which systolic pressure and right ventricular hypertrophy were assessed. Transient intracellular calcium was monitored using a fluorescence imaging system. Muscle tension was measured with a contractile force recording system, and protein expression was assessed by immunoblotting. We found that the expressions of RhoA and ROCK were increased in mouse pulmonary arteries (PAs) under conditions of chronic hypoxia. Inhibition of the RhoA/ROCK signaling pathway prevented the development of hypoxic pulmonary hypertension (HPH), as evidenced by significantly reduced PA remodeling and pulmonary vasoconstriction. Immunoblotting results revealed that inhibition of the RhoA/ROCK signaling pathway significantly decreased the expression of HIF-1α. Knockdown of HIF-1α down-regulated the expression and function of the TRPC1 and TRPC6 channels in PASMCs under conditions of hypoxia. Contraction of the PAs and a Ca2+ influx into PASMCs through either receptor- or store-operated Ca2+ channels were also increased after hypoxia. However, RhoA/ROCK inhibitors markedly attenuated these changes. These results indicate that inhibition of the RhoA/ROCK signaling pathway ameliorates HPH via HIF-1α-dependent functional TRPCs.

PFKFB3 promotes endotoxemia-induced myocardial dysfunction through inflammatory signaling and apoptotic induction.

Cardiac dysfunction is a vital complication during endotoxemia (ETM). Accumulating evidence suggests that enhanced glycolytic metabolism promotes inflammatory and myocardial diseases. In this study, we performed deep mRNA sequencing analysis on the hearts of control and lipopolysaccharide (LPS)-challenged mice (40 mg/kg, i.p.) and identified that the glycolytic enzyme, 6-phosphofructo-2-kinase (PFK-2)/fructose-2,6-bisphosphatase 3 (PFKFB3) might play an indispensable role in ETM-induced cardiac damage. Quantitative real-time PCR validated the transcriptional upregulation of PFKFB3 in the myocardium of LPS-challenged mice and immunoblotting and immunostaining assays confirmed that LPS stimulation markedly increased the expression of PFKFB3 at the protein level both in vivo and in vitro. The potent antagonist 3-(3pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO) was used to block PFKFB3 activity in vivo (50 mg/kg, i.p.) and in vitro (10 µM). Echocardiographic analysis and TUNEL staining showed that 3PO significantly alleviated LPS-induced cardiac dysfunction and apoptotic injury in vivo. 3PO also suppressed the LPS-induced secretion of tumor necrosis factor-α, interleukin (IL)-1ß, IL-6 and lactate in the serum, in addition to lactate in the myocardium. PFKFB3 inhibition also diminished the nuclear translocation and phosphorylation of transcription factor nuclear factor-κB (NF-κB) in both adult cardiomyocytes and HL-1 cells. Furthermore, immunoblotting analysis showed that 3PO inhibited LPS-induced apoptotic induction in cardiomyocytes. Taken together, these findings demonstrate that PFKFB3 participates in LPS-induced cardiac dysfunction via mediating inflammatory and apoptotic signaling pathway.

Effects and mechanisms of Xiaochaihu Tang against liver fibrosis: An integration of network pharmacology, molecular docking and experimental validation.

ETHNOPHARMACOLOGICAL RELEVANCE: Liver fibrosis is a potentially harmful chronic liver disease caused by various etiologies. There is currently no specific drug for liver fibrosis. Xiaochaihu Tang (XCHT) is a traditional formula combined of seven herbs, which was first recorded in the Treatise on Febrile Diseases in Han Dynasty of ancient China. It is widely used in clinic to hepatic protection, analgesic, antipyretic and anti-inflammatory treatment. And it has been recommended for treating chronic hepatitis and chronic cholecystitis in the latest guidelines for the diagnosis and treatment of liver fibrosis with integrated traditional and western medicine. However, the underlying regulatory mechanisms remain elusive. AIM OF THE STUDY: This study aims to explore the therapeutic effects of XCHT on liver fibrosis and its underlying molecular mechanisms from the perspective of network pharmacology and experimental research. MATERIALS AND METHODS: Carbon tetrachloride (CCl4) induced and bile duct ligation (BDL) induced liver fibrosis models in mice were established to evaluate the anti-fibrosis effects of XCHT in vivo. Potential anti-fibrosis targets of XCHT were screened via network establishment. The underlying mechanisms were uncovered through GO and pathway enrichment analysis. Then, the core targets were identified from protein-protein interaction network by means of the Cytohubba plug-in of Cytoscape. Furthermore, two effective monomer components of XCHT were recognized by molecular docking. Moreover, the predicted components and pathways were verified by in vitro experiments. RESULTS: When treated with XCHT, liver fibrosis was alleviated in both mice models, showing as the improvement of liver function, the protection of hepatocytes, the inhibition of HSC activation and the reduction of hepatic collagen accumulation. 540 monomer components, 300 therapeutic targets, 109 signaling pathways, 246 GO biological processes, 77 GO cellular components, 107 GO molecular functions items and core targets were identified by network analysis. Then, 6-gingerol and baicalein were identified as the core components of anti-fibrosis effects of XCHT via leptin or Nrf2 signaling pathway. Furthermore, the experiment in vitro also validated the results. CONCLUSIONS: Our study suggests XCHT could alleviate liver fibrosis through multi-targets and multi-pathways; 6-gingerol and baicalein are its core components which may play an important role via leptin or Nrf2 signaling pathway.

Canonical transient receptor potential channel 1 aggravates myocardial ischemia-and-reperfusion injury by upregulating reactive oxygen species.

The canonical transient receptor potential channel (TRPC) proteins form Ca2+-permeable cation channels that are involved in various heart diseases. However, the roles of specific TRPC proteins in myocardial ischemia/reperfusion (I/R) injury remain poorly understood. We observed that TRPC1 and TRPC6 were highly expressed in the area at risk (AAR) in a coronary artery ligation induced I/R model. Trpc1-/- mice exhibited improved cardiac function, lower serum Troponin T and serum creatine kinase level, smaller infarct volume, less fibrotic scars, and fewer apoptotic cells after myocardial-I/R than wild-type or Trpc6-/- mice. Cardiomyocyte-specific knockdown of Trpc1 using adeno-associated virus 9 mitigated myocardial I/R injury. Furthermore, Trpc1 deficiency protected adult mouse ventricular myocytes (AMVMs) and HL-1 cells from death during hypoxia/reoxygenation (H/R) injury. RNA-sequencing-based transcriptome analysis revealed differential expression of genes related to reactive oxygen species (ROS) generation in Trpc1-/- cardiomyocytes. Among these genes, oxoglutarate dehydrogenase-like (Ogdhl) was markedly downregulated. Moreover, Trpc1 deficiency impaired the calcineurin (CaN)/nuclear factor-kappa B (NF-κB) signaling pathway in AMVMs. Suppression of this pathway inhibited Ogdhl upregulation and ROS generation in HL-1 cells under H/R conditions. Chromatin immunoprecipitation assays confirmed NF-κB binding to the Ogdhl promoter. The cardioprotective effect of Trpc1 deficiency was canceled out by overexpression of NF-κB and Ogdhl in cardiomyocytes. In conclusion, our findings reveal that TRPC1 is upregulated in the AAR following myocardial I/R, leading to increased Ca2+ influx into associated cardiomyocytes. Subsequently, this upregulates Ogdhl expression through the CaN/NF-κB signaling pathway, ultimately exacerbating ROS production and aggravating myocardial I/R injury.

Old targets, new strategy: Apigenin-7-O-ß-d-(-6″-p-coumaroyl)-glucopyranoside prevents endothelial ferroptosis and alleviates intestinal ischemia-reperfusion injury through HO-1 and MAO-B inhibition.

With the increasing morbidity and mortality, intestinal ischemia/reperfusion injury (IIRI) has attracted more and more attention, but there is no efficient therapeutics at present. Apigenin-7-O-ß-D-(-6″-p-coumaroyl)-glucopyranoside (APG) is a new flavonoid glycoside isolated from Clematis tangutica that has strong antioxidant abilities in previous studies. However, the pharmacodynamic function and mechanism of APG on IIRI remain unknown. This study aimed to investigate the effects of APG on IIRI both in vivo and in vitro and identify the potential molecular mechanism. We found that APG could significantly improve intestinal edema and increase Chiu's score. MST analysis suggested that APG could specifically bind to heme oxygenase 1 (HO-1) and monoamine oxidase b (MAO-B). Simultaneously, APG could attenuate ROS generation and Fe2+ accumulation, maintain mitochondria function thus inhibit ferroptosis with a dose-dependent manner. Moreover, we used siRNA silencing technology to confirm that knocking down both HO-1 and MAO-B had a positive effect on intestine. In addition, we found the HO-1 and MAO-B inhibitors also could reduce endothelial cell loss and protect vascular endothelial after reperfusion. We demonstrate that APG plays a protective role on decreasing activation of HO-1 and MAO-B, attenuating IIRI-induced ROS generation and Fe2+ accumulation, maintaining mitochondria function thus inhibiting ferroptosis.

Ligustroflavone ameliorates CCl4-induced liver fibrosis through down-regulating the TGF-ß/Smad signaling pathway.

Liver fibrosis is a pathological process characterized by excess deposition of extracellular matrix (ECM) that are mainly derived from activated hepatic stellate cells. Previous studies suggested that ligustroflavone (LF) was an ingredient of Ligustrum lucidum Ait. with activities of anti-inflammation and anti-oxidation. In this study, we investigated whether LF had any effect on liver fibrosis. In our study, we established a mouse model of carbon tetrachloride (CCl4)-induced liver fibrosis and used TGF-ß1-stimulated human hepatic stellate cell line (LX-2) to explore the effect of LF and associated underlying mechanism. LF was used in vivo with low dose (L-LF, 5 mg·kg-1, i.p., 3 times each week) and high dose (H-LF, 20 mg·kg-1, i.p., 3 times each week) and in vitro (25 µmol·L-1). Histopathological and biochemical assays investigations showed that LF delayed the formation of liver fibrosis; decreased AST, ALT activities and increased Alb activity in serum; decreased MDA level, Hyp content and increased GSH-Px concentration, SOD activity in liver tissues. Moreover, immunohistochemical, immunofluorescent and Western blot results showed that LF reduced the expressions of hepatic stellate cells specific marker proteins, including collagen I and α-SMA in vivo and in vitro. In addition, LF markedly suppressed TGF-ß1-upregulated protein expressions of TßR I, TßR II, P-Smad2, P-Smad3 and Smad4 in LX-2 cells. Taken together, these findings demonstrated LF could decrease histopathological lesions, ameliorate oxidative injury, attenuate CCl4-induced liver fibrosis, which may be associated with down-regulating the TGF-ß/Smad signaling pathway.

TRPC1 promotes the genesis and progression of colorectal cancer via activating CaM-mediated PI3K/AKT signaling axis.

Transient receptor potential canonical (TRPC) channels are the most prominent nonselective cation channels involved in various diseases. However, the function, clinical significance, and molecular mechanism of TRPCs in colorectal cancer (CRC) progression remain unclear. In this study, we identified that TRPC1 was the major variant gene of the TRPC family in CRC patients. TRPC1 was upregulated in CRC tissues compared with adjacent normal tissues and high expression of TRPC1 was associated with more aggressive tumor progression and poor overall survival. TRPC1 knockdown inhibited cell proliferation, cell-cycle progression, invasion, and migration in vitro, as well as tumor growth in vivo; whereas TRPC1 overexpression promoted colorectal tumor growth and metastasis in vitro and in vivo. In addition, colorectal tumorigenesis was significantly attenuated in Trpc1-/- mice. Mechanistically, TRPC1 could enhance the interaction between calmodulin (CaM) and the PI3K p85 subunit by directly binding to CaM, which further activated the PI3K/AKT and its downstream signaling molecules implicated in cell cycle progression and epithelial-mesenchymal transition. Silencing of CaM attenuated the oncogenic effects of TRPC1. Taken together, these results provide evidence that TRPC1 plays a pivotal oncogenic role in colorectal tumorigenesis and tumor progression by activating CaM-mediated PI3K/AKT signaling axis. Targeting TRPC1 represents a novel and specific approach for CRC treatment.

Cardioprotective effects of galectin-3 inhibition against ischemia/reperfusion injury.

Myocardial ischemia/reperfusion (IR) injury is caused by the restoration of the coronary blood flow following an ischemic episode. Accumulating evidence suggests that galectin-3, a ß-galactoside-binding lectin, acts as a biomarker in heart disease. However, it remains unclear whether manipulating galectin-3 affects the susceptibility of the heart to IR injury. In this study, RNA sequencing (RNA-seq) analysis identified that Lgals3 (galecin-3) plays an indispensable role in IR-induced cardiac damage. Immunostaining and immunoblot assays confirmed that the expression of galectin-3 was markedly increased in myocardial IR injury both in vivo and in vitro. Echocardiographic analysis showed that cardiac dysfunction in experimental IR injury was significantly attenuated by galectin-3 inhibitors including pectin (1%, i.p.) from citrus and binding peptide G3-C12 (5.0 mg/kg, i.p.). Galectin-3 inhibitor-treated mice exhibited smaller infarct sizes and decreased tissue injury. Furthermore, TUNEL staining showed that galectin-3 inhibition suppressed IR-mediated cardiomyocyte apoptosis. Mitochondrial membrane potential (MMP) and mitochondrial permeability transition pore (mPTP) levels were well-preserved and IR-induced changes of mitochondrial cyto c, cytosol cyto c, caspase-9, caspase-3, Bcl-2 and Bax in the galectin-3 inhibitor-treated groups were observed. Our findings indicate that the pathological upregulation of galectin-3 contributes to IR-induced cardiac dysfunction and that galectin-3 inhibition ameliorates myocardial injury, highlighting its therapeutic potential.