Secreted frizzled related protein 1 protects H9C2 cells from hypoxia/re-oxygenation injury by blocking the Wnt signaling pathway

Extracellular Vesicles Derived from Osteogenic-Differentiated Human Bone Marrow-Derived Mesenchymal Cells Rescue Osteogenic Ability of Bone Marrow-Derived Mesenchymal Cells Impaired by Hypoxia

In orthopedics, musculoskeletal disorders, i.e., non-union of bone fractures or osteoporosis, can have common histories and symptoms related to pathological hypoxic conditions induced by aging, trauma or metabolic disorders. Here, we observed that hypoxic conditions (2% O2) suppressed the osteogenic differentiation of human bone marrow-derived mesenchymal cells (hBMSC) in vitro and simultaneously increased reactive oxygen species (ROS) production. We assumed that cellular origin and cargo of extracellular vesicles (EVs) affect the osteogenic differentiation capacity of hBMSCs cultured under different oxygen pressures. Proteomic analysis revealed that EVs isolated from osteogenic differentiated hBMSC cultured under hypoxia (hypo-osteo EVs) or under normoxia (norm-osteo EVs) contained distinct protein profiles. Extracellular matrix (ECM) components, antioxidants and pro-osteogenic proteins were decreased in hypo-osteo EVs. The proteomic analysis in our previous study revealed that under normoxic culture conditions, pro-osteogenic proteins and ECM components have higher concentrations in norm-osteo EVs than in EVs derived from naïve hBMSCs (norm-naïve EVs). When selected for further analysis, five anti-hypoxic proteins were significantly upregulated (response to hypoxia) in norm-osteo EVs. Three of them are characterized as antioxidant proteins. We performed qRT-PCR to verify the corresponding gene expression levels in the norm-osteo EVs' and norm-naïve EVs' parent cells cultured under normoxia. Moreover, we observed that norm-osteo EVs rescued the osteogenic ability of naïve hBMSCs cultured under hypoxia and reduced hypoxia-induced elevation of ROS production in osteogenic differentiated hBMSCs, presumably by inducing expression of anti-hypoxic/ antioxidant and pro-osteogenic genes.

Protective effects of safranal on hypoxia/reoxygenation-induced injury in H9c2 cardiac myoblasts via the PI3K/AKT/GSK3β signaling pathway

Safranal (SFR), an active ingredient extracted from saffron, exhibits a protective effect on the cardiovascular system. However, the mechanism of SFR against hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury has previously not been investigated in vitro. The aim of the present study was therefore to observe the protective effects of SFR on H/R-induced cardiomyocyte injury and to explore its mechanisms. A H/R injury model of H9c2 cardiac myoblasts was established by administering 800 µmol/l CoCl₂ to H9c2 cells for 24 h and reoxygenating the cells for 4 h to induce hypoxia. H9c2 cardiac myoblasts were pretreated with SFR for 12 h to evaluate the associated protective effects. A Cell Counting Kit-8 assay was used for cell viability detection, and the expression levels of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), glutathione peroxidase (GSH-px), catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA) and caspase-3, and the intracellular Ca²⁺ concentration were measured using the corresponding commercial kits. Levels of reactive oxygen species (ROS) in the cells were detected using 2,7-dichlorodihydrofluorescein diacetate. Flow cytometry was used to determine the degree of apoptosis and the level of mitochondrial membrane potential (MMP). Moreover, the expression levels of phosphorylated (p-)PI3K, AKT, p-AKT, glycogen synthase kinase 3β (GSK3β), p-GSK3β, Bcl-2, Bax, caspase-3 and cleaved caspase-3 were measured using western blot analysis. Results of the present study demonstrated that the H9c2 cardiac myoblasts treated with SFR exhibited significantly improved levels of viability and significantly reduced levels of ROS, compared with the H/R group. Furthermore, compared with the H/R group, SFR treatment significantly increased the MMP levels and antioxidant enzyme levels, including CAT, SOD and GSH-px; whereas the levels of CK-MB, LDH, MDA and intracellular Ca²⁺ concentration were significantly decreased. Moreover, the results of the present study demonstrated that SFR significantly reduced caspase-3, cleaved caspase-3 and Bax protein expression levels, but upregulated the Bcl-2 protein expression levels. SFR also increased the protein expressions of PI3K/AKT/GSK3β. In summary, the results suggested that SFR may exert a protective effect against H/R-induced cardiomyocyte injury, which occurs in connection with the inhibition of oxidative stress and apoptosis via regulation of the PI3K/AKT/GSK3β signaling pathway.

Large Clostridial Toxins: Mechanisms and Roles in Disease

Large clostridial toxins (LCTs) are a family of bacterial exotoxins that infiltrate and destroy target cells. Members of the LCT family include Clostridioides difficile toxins TcdA and TcdB, Paeniclostridium sordellii toxins TcsL and TcsH, Clostridium novyi toxin TcnA, and Clostridium perfringens toxin TpeL. Since the 19th century, LCT-secreting bacteria have been isolated from the blood, organs, and wounds of diseased individuals, and LCTs have been implicated as the primary virulence factors in a variety of infections, including C. difficile infection and some cases of wound-associated gas gangrene. Clostridia express and secrete LCTs in response to various physiological signals. LCTs invade host cells by binding specific cell surface receptors, ultimately leading to internalization into acidified vesicles. Acidic pH promotes conformational changes within LCTs, which culminates in translocation of the N-terminal glycosyltransferase and cysteine protease domain across the endosomal membrane and into the cytosol, leading first to cytopathic effects and later to cytotoxic effects. The focus of this review is on the role of LCTs in infection and disease, the mechanism of LCT intoxication, with emphasis on recent structural work and toxin subtyping analysis, and the genomic discovery and characterization of LCT homologues. We provide a comprehensive review of these topics and offer our perspective on emerging questions and future research directions for this enigmatic family of toxins.

MeCP2 attenuates cardiomyocyte hypoxia/reperfusion-induced injury via regulation of the SFRP4/Wnt/β-catenin axis

Objective: Methylated CpG binding protein 2 (MeCP2) is closely associated with heart failure, but its role in I/R injury remains unclear. The purpose of this study was to explore the role and underling mechanism of MeCP2 in myocardial I/R injury.Methods: Hypoxia/reperfusion (H/R)-induced H9c2 cardiomyocytes was used to establish an in vitro I/R injury model. Oxidative stress was assessed by measuring reactive oxygen species (ROS) generation, malondialdehyde (MDA) content and superoxide dismutase (SOD) activity. Cell viability and cell cycle arrest were evaluated by the Cell Counting Kit-8 assay and cell cycle assay, respectively. Apoptosis was determined using flow cytometry analysis.Results: The expression of MeCP2 in H9c2 cells was decreased after H/R treatment. The overexpression of MeCP2 inhibited H/R-induced oxidative stress, cell cycle arrest and apoptosis of H9c2 cells. Moreover, MeCP2 inhibited the activation of secreted frizzled related protein 4 (SFRP4)/Wnt/β-catenin axis, and SFRP4 relieved the effect of MeCP2 on oxidative stress, cell cycle arrest and apoptosis in H/R-induced H9c2 cells.Conclusions: MeCP2 attenuated H/R-induced injury in H9c2 cardiomyocytes by modulating the SFRP4/Wnt/β-catenin axis, which suggested that MeCP2 might serve as a therapeutic target of patients with AMI after reperfusion.

Sfrp1 protects against acute myocardial ischemia (AMI) injury in aged mice by inhibiting the Wnt/β-catenin signaling pathway

BACKGROUND

Aged patients suffering from acute myocardial ischemia (AMI) exhibit an increased mortality rate and worse prognosis, and a more effective treatment is currently in need. In the present study, we investigated potent targets related to Wnt/β-catenin pathway deregulation for AMI injury treatment.

METHODS

In the present study, AAV-Sfrp1 was transduced into the myocardium of aged mice, and an AMI model was established in these aged mice to study the effect and molecular mechanism of Sfrp1 overexpression on AMI-induced injury.

RESULTS

The results showed that Sfrp1 was successfully overexpressed in the myocardium of aged mice and remarkably reduced Wnt/β-catenin pathway activity in aged mice after AMI, effectively reducing the degree of myocardial fibrosis, inhibiting cardiomyocyte apoptosis, and improving cardiac function. We revealed that the exogenous introduction of Sfrp1 could be considered a promising strategy for improving post-AMI injury in aged mice by inhibiting Wnt/β-catenin pathway activity.

CONCLUSIONS

In conclusion, the Wnt/β-catenin pathway potentially represents a key target in AMI in aged mice. Sfrp1 might be used as a small molecule gene therapy drug to improve heart function, reduce the degree of myocardial fibrosis, inhibit cardiomyocyte apoptosis and reduce AMI injury in aged mice by inhibiting the Wnt/β-catenin pathway, thereby effectively protecting aged hearts from AMI injury.

Secreted Frizzled Related Proteins in Cardiovascular and Metabolic Diseases

Abnormal gene expression and secreted protein levels are accompanied by extensive pathological changes. Secreted frizzled related protein (SFRP) family members are antagonistic inhibitors of the Wnt signaling pathway, and they were recently found to be involved in the pathogenesis of a variety of metabolic diseases, which has led to extensive interest in SFRPs. Previous reports highlighted the importance of SFRPs in lipid metabolism, obesity, type 2 diabetes mellitus and cardiovascular diseases. In this review, we provide a detailed introduction of SFRPs, including their structural characteristics, receptors, inhibitors, signaling pathways and metabolic disease impacts. In addition to summarizing the pathologies and potential molecular mechanisms associated with SFRPs, this review further suggests the potential future use of SFRPs as disease biomarkers therapeutic targets.

Emerging role of circular RNA in intervertebral disc degeneration: Knowns and unknowns (Review)

Lower back pain (LBP) is one of the predominant factors contributing to dyskinesia and remains a serious social and economic burden worldwide. Intervertebral disc degeneration (IDD) is the leading cause of LBP; the existing IDD treatments cannot completely prevent IDD. Circular RNAs (circRNAs) are non‑coding RNAs resulting from back‑splicing with unique structural characteristics and functions. Accumulating evidence suggests that circRNAs are involved in the pathological process of IDD and modulate a range of IDD‑related genes or proteins. However, the underlying circRNA‑mediated regulatory mechanisms remain poorly understood. The aim of the present review is to describe the current understanding of circRNA characteristics, classification, biogenesis and function in relation to its specific roles in IDD. Additionally, the limitations on the current knowledge in the field and the future direction of IDD‑related research are also discussed.

sFRP1 protects H9c2 cardiac myoblasts from doxorubicin-induced apoptosis by inhibiting the Wnt/PCP-JNK pathway

Doxorubicin (Dox) is an effective chemotherapy drug against a wide range of cancers, including both hematological and solid tumors. However, the serious cardiotoxic effect restricted its clinical application. We previously have illuminated the protective role of canonical Wnt/β-catenin signaling in Dox-induced cardiotoxicity. Secreted frizzled-related protein 1 (sFRP1) is one of the endogenous inhibitors of both canonical and noncanonical Wnt signaling. In this study, we investigated the relationship between sFRP1 and noncanonical Wnt/PCP-JNK (Wnt/planar cell polarity-c-Jun N-terminal kinase) pathway in Dox-induced cardiotoxicity in vitro and in vivo. We showed that treatment of H9c2 cardiac myoblasts with Dox (1 μM) time-dependently suppressed cell viability accompanied by significantly decreased sFRP1 protein level and increased Wnt/PCP-JNK signaling. Pretreatment with SP600125, the Wnt/PCP-JNK signaling inhibitor, attenuated Dox-induced apoptosis of H9c2 cells. Overexpression of sFRP1 protected H9c2 cells from Dox-induced apoptosis by inhibiting the Wnt/PCP-JNK pathway. After intraperitoneal injection of a cumulative dose of 15 mg/kg Dox, rats displayed significant cardiac dysfunction; their heart showed inhibited Wnt/β-catenin signaling and activated Wnt/PCP-JNK signaling. These results suggest that sFRP1 may be a novel target for Dox-induced cardiotoxicity.

Role of Sfrps in cardiovascular disease

Secreted frizzled-related proteins (Sfrps) are a family of secreted proteins that bind extracellularly to Wnt ligands and frizzled receptors. This binding modulates the Wnt signaling cascade, and Sfrps interact with their corresponding receptors. Sfrps are thought to play an important role in the pathological mechanism of cardiac disease such as myocardial infarction, cardiac remodeling, and heart failure. However, the overall role of Sfrps in cardiac disease is unknown. Some members of the Sfrps family modulate cellular apoptosis, angiogenesis, differentiation, the inflammatory process, and cardiac remodeling. In this review, we summarize the evidence of Sfrps association with cardiac disease. We also discuss how multiple mechanisms may underlie Sfrps being involved in such diverse pathologies.

The administration of dexmedetomidine changes microRNA expression profiling of rat hearts

BACKGROUND

Dexmedetomidine is widely used for perioperative and ICU patients. microRNAs (miRNAs) function as regulators of gene expression. The aim of the study was to assay expression profiling of microRNA in rat hearts following administration of dexmedetomidine.

METHODS

In this study 6 rats were randomly divided into two groups (n = 3): dexmedetomidine group and control group. The rats of dexmedetomidine group were intraperitoneally given dexmedetomidine in a dose of 100 μg/kg whereas the rats in control group were administered normal saline intraperitoneally. The hearts were excised 30 min after the administration of dexmedetomidine or normal saline under anesthesia. The samples were analyzed for differentially expressed microRNAs with Exiqon miRNA Array. The differentially expressed microRNAs were confirmed by using qRT-PCR. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to find the target genes and signaling pathways of the aberrantly expressed miRNAs.

RESULTS

Six microRNAs were identified to be significantly expressed, among of which, five microRNAs (miRNA-434-3p, miRNA-3596d, miRNA-496-5p, miRNA-7a-2-3p and miRNA-702-3p) were up-regulated and 1 microRNA (miRNA-208b-3p) down-regulated compared to those of control group. The aberrantly expressed microRNAs were further validated by Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). GO and KEGG analyses were used to identify target genes and the signaling pathways.

CONCLUSIONS

The use of dexmedetomidine is associated with differentially expressed microRNAs which may be involved in cardioprotection following administration of dexmedetomidine.

Silencing microRNA-27a inhibits proliferation and invasion of human osteosarcoma cells through the SFRP1-dependent Wnt/β-catenin signaling pathway

Osteosarcoma is the most common malignant tumor of bone with a high potential for metastasis. Importantly, microRNA-27a (miR-27a) is involved in the progression of osteosarcoma. The present study aims to discuss the effects of miR-27a and its target gene secreted frizzled related protein 1 (SFRP1) on proliferation and invasion of human osteosarcoma cells via Wnt/β-catenin signaling pathway. The expression of miR-27a and SFRP1 in osteosarcoma tissues and cells was detected, followed by identification of their relations. Subsequently, miR-27a mimic, miR-27a inhibitor, or siRNA against SFRP1 were introduced into cells (HOS and U2OS) to investigate their role in cell proliferation and invasion. The expression of Wnt/β-catenin signaling pathway-related gene was analyzed to further uncover the regulatory mechanism of miR-27a. The osteosarcoma tissues and cells exhibited elevated miR-27 expression and reduced SFRP1 expression. SFRP1 was verified to be a target gene of miR-27a. Meanwhile, silenced miR-27a inhibited proliferation and invasion of human osteosarcoma cells. Finally, silencing miR-27a inhibited the activation of Wnt/β-catenin signaling pathway, evidenced by reduced β-catenin expression. Our study draws a conclusion that silencing miR-27a dampens osteosarcoma progression, which might be achieved through the inactivation of the Wnt/β-catenin signaling pathway by up-regulating SFRP1.

Protective effect of T3 peptide, an active fragment of tumstatin, against ischemia/reperfusion injury in rat heart

Ischemia/reperfusion (I/R)-induced oxidative stress is a serious clinical problem in the reperfusion therapy for ischemic diseases. Tumstatin is an endogenous bioactive peptide cleaved from type IV collagen α3 chain. We previously reported that T3 peptide, an active subfragment of tumstatin, exerts cytoprotective effects on H₂O₂-induced apoptosis through the inhibition of intracellular reactive oxygen species (ROS) production in H9c2 cardiomyoblasts. In this study, we investigated whether T3 peptide has cardioprotective effects against I/R injury by using in vitro and ex vivo experimental models. H9c2 cardiomyoblasts were stimulated with oxygen and glucose deprivation (OGD) for 12 h followed by reoxygenation for 1-8 h (OGD/R; in vitro model). The cells were treated with T3 peptide (30-1000 ng/ml) during OGD. Ten minutes after the pre-perfusion of T3 peptide (300 ng/ml), Langendorff perfused rat hearts were exposed to ischemia for 30 min followed by reperfusion for 1 h (ex vivo model). T3 peptide inhibited OGD/R-induced apoptosis through the inhibition of mitochondrial ROS production and dysfunction in H9c2 cardiomyoblasts. T3 peptide also prevented I/R-induced cardiac dysfunction, arrhythmia and myocardial infarction in the perfused rat heart. In conclusion, we for the first time demonstrated that T3 peptide exerts cardioprotective effects against I/R injury.

sFRP1 has a biphasic effect on doxorubicin-induced cardiotoxicity in a cellular location-dependent manner in NRCMs and Rats

Doxorubicin (Dox) is an effective anticancer drug, however, its clinical application is restricted by the life-threatening cardiotoxic effects. Secreted Frizzled-related protein 1 (sFRP1) has been reported to participate in both the cancer and cardiovascular diseases and was one of the differential expression genes in normal hearts compared with Dox-treated hearts. Thus, it is important to reveal the potential role of sFRP1 in Dox-induced cardiotoxicity. Here, we show that sFRP1 has a biphasic effect on Dox-induced cardiotoxicity in a location-dependent manner. The secretion of sFRP1 was significantly increased in Dox-treated neonatal rat cardiomyocytes (NRCMs) (1 µM) and SD rats (5 mg/kg/injection at day 1, 5, and 9, i.p.). Adding the anti-sFRP1 antibody (0.5 µg/ml) and inhibiting sFRP1 secretion by caffeine (5 mM) both relieved Dox-induced cardiotoxicity through activating Wnt/β-catenin signaling, whereas increasing the secretion of sFRP1 by heparin (100 µg/ml) had the opposite effect. The intracellular level of sFRP1 was significantly decreased after Dox treatment both in vitro and in vivo. Knockdown of sFRP1 by sgRNA aggravated Dox-induced cardiotoxicity, while moderate overexpression of sFRP1 by Ad-sFRP1 exhibited protective effect. Besides, poly(ADP-ribosyl) polymerase-1 (PARP1) was screened as an interacting partner of sFRP1 in NRCMs by mass spectrometry. Our results suggested that the intracellular sFRP1 protected NRCMs from Dox-induced cardiotoxicity by interacting with PARP1. Thus, our results provide a novel evidence that sFRP1 has a biphasic effect on Dox-induced cardiotoxicity. In addition, the oversecretion of sFRP1 might be used as a biomarker to indicate the occurrence of cardiotoxicity induced by Dox treatment.

Sfrp1 attenuates TAC-induced cardiac dysfunction by inhibiting Wnt signaling pathway- mediated myocardial apoptosis in mice

Background

Hemodynamic overload causes cardiac hypertrophy leading to heart failure. Wnt signaling pathway was reported activated in heart failure. Secreted frizzled related protein 1 (Sfrp1) is a suppressor of Wnt signaling activation. The aim of the present study was to investigate the protective effect of Sfrp1 on hemodynamic overload- induced cardiac dysfunction.

Methods

A mice transverse aortic constriction (TAC)- induced heart failure model was established. A recombinant adeno-associated virus 9 (AAV9) vector was used to deliver Sfrp1 gene into myocardium. Fluorescence and immunohistochemistry staining was used to evaluate the effectiveness of viral vector delivery. Invasive hemodynamic examination was used to evaluate cardiac systolic and diastolic functions. Myocardium apoptosis was detected by TUNEL assay. The expression levels of Sfrp1, β-catenin, caspase3, Bax, Bcl-2 and c-Myc were measured by Western blotting.

Results

Increased mean arterial pressure and impaired cardiac function confirmed the establishment of TAC model. Sfrp1 protein expression was effectively increased in myocardium of mice treated with AAV9-Sfrp1 viral vector. The viral vector administration improved both systolic and diastolic cardiac functions by reducing myocardial apoptosis in TAC mice. The expression levels of β-catenin, caspase3 and Bax were significantly reduced while the expression levels of Bcl-2 and c-Myc were dramatically increased in myocardium by the viral vector treatment in TAC mice.

Conclusions

AAV9 viral vector delivered sfrp1 expression gene into myocardium, which attenuated TAC-induced cardiac dysfunction by inhibiting Wnt signaling pathway activation- mediated apoptosis.

Mild hypothermia protects against oxygen glucose deprivation/reoxygenation-induced apoptosis via the Wnt/β-catenin signaling pathway in hippocampal neurons

Mild hypothermia is thought to be one of the most effective therapies for cerebral ischemia/reperfusion injuries. Our previous research revealed that mild hypothermia inhibits the activation of caspase-3 and protects against oxygen glucose deprivation/reoxygenation (OGD/R)-induced injury in hippocampal neurons. However, the mechanisms behind the activation of caspase-3 remain unclear. The aims of this study were to determine whether the protective effects of mild hypothermia were exerted through the Wnt/β-catenin signaling pathway. We found that, under OGD/R conditions, the pathway was down regulated, but mild hypothermia induced the reactivation of the Wnt/β-catenin signaling pathway, which had been suppressed by OGD/R injury. Mild hypothermia also caused the down regulation of the expression of apoptosis promoting proteins (Bax cleaved caspase-3), up-regulated the expression of apoptosis inhibiting proteins (Bcl-2), and ameliorated OGD/R injury-induced apoptosis. The protective effects of mild hypothermia were blocked by DKK1 (an antagonist of the canonical Wnt signaling pathway). Taken together, these results indicate that the Wnt/β-catenin signaling pathway mediates the protective effects of mild hypothermia against OGD/R-induced apoptosis. Our study provides evidence that mild hypothermia reactivates the Wnt/β-catenin signaling pathway, which is suppressed by OGD/R injury, in hippocampal neurons and protects neurons from OGD/R-induced apoptosis via the reactivation of the Wnt/β-catenin signaling pathway, ultimately suggesting that mild hypothermia could have therapeutic effects on OGD/R-induced apoptosis.

Potential Effects of Corneal Cross-Linking upon the Limbus

Corneal cross-linking is nowadays the most used strategy for the treatment of keratoconus and recently it has been exploited for an increasing number of different corneal pathologies, from other ectatic disorders to keratitis. The safety of this technique has been widely assessed, but clinical complications still occur. The potential effects of cross-linking treatment upon the limbus are incompletely understood; it is important therefore to investigate the effect of UV exposure upon the limbal niche, particularly as UV is known to be mutagenic to cellular DNA and the limbus is where ocular surface tumors can develop. The risk of early induction of ocular surface cancer is undoubtedly rare and has to date not been published other than in one case after cross-linking. Nevertheless it is important to further assess, understand, and reduce where possible any potential risk. The aim of this review is to summarize all the reported cases of a pathological consequence for the limbal cells, possibly induced by cross-linking UV exposure, the studies done in vitro or ex vivo, the theoretical bases for the risks due to UV exposure, and which aspects of the clinical treatment may produce higher risk, along with what possible mechanisms could be utilized to protect the limbus and the delicate stem cells present within it.