Endothelial cell calpain as a critical modulator of angiogenesis

Testing calpain inhibition in tumor endothelial cells: novel targetable biomarkers against glioblastoma malignancy

Introduction

Glioblastoma IDH-wildtype (GBM) is the most malignant brain tumor in adults, with a poor prognosis of approximately 15 months after diagnosis. Most patients suffer from a recurrence in <1 year, and this renders GBM a life-threatening challenge. Among molecular mechanisms driving GBM aggressiveness, angiogenesis mediated by GBM endothelial cells (GECs) deserves consideration as a therapeutic turning point. In this scenario, calpains, a family of ubiquitously expressed calcium-dependent cysteine proteases, emerged as promising targets to be investigated as a novel therapeutic strategy and prognostic tissue biomarkers.

Methods

To explore this hypothesis, GECs were isolated from n=10 GBM biopsies and characterized phenotypically by immunofluorescence. The expression levels of calpains were evaluated by qRT-PCR and Western blot, and their association with patients' prognosis was estimated by Pearson correlation and Kaplan-Meier survival analysis. Calpain targeting efficacy was assessed by a time- and dose-dependent proliferation curve, MTT assay for viability, caspase-3/7 activity, migration and angiogenesis in vitro, and gene and protein expression level modification.

Results

Immunofluorescence confirmed the endothelial phenotype of our primary GECs. A significant overexpression was observed for calpain-1/2/3 (CAPN) and calpain-small-subunits-1/2 (CAPNS1), whereas calpastatin gene, the calpain natural inhibitor, was reported to be downregulated. A significant negative correlation was observed between CAPN1/CAPNS1 and patient overall survival. GEC challenging revealed that the inhibition of calpain-1 exerts the strongest proapoptotic efficacy, so GEC mortality reached the 80%, confirmed by the increased activity of caspase-3/7. Functional assays revealed a strong affection of in vitro migration and angiogenesis. Gene and protein expression proved a downregulation of MAPK, VEGF/VEGFRs, and Bcl-2, and an upregulation of caspases and Bax-family mediators.

Conclusion

Overall, the differential expression of calpains and their correlation with patient survival suggest a novel promising target pathway, whose blockade showed encouraging results toward precision medicine strategies.

Association of angiogenesis-associated genes with atherosclerotic plaque progression, intraplaque hemorrhage, and immune infiltration

Mounting evidence suggests that intraplaque angiogenesis is associated with the progression of atherosclerotic plaques and the development of intraplaque hemorrhage. The specificity of intraplaque immune cell infiltration may be associated with abnormalities in the structure and function of the nascent capillaries. Here, we analyzed expression levels of angiogenesis-associated genes in early and advanced carotid atheromatous plaque tissues as well as in stable and intraplaque hemorrhage plaques. Expression profiles of advanced arterial plaques based on angiogenesis-associated genes were classified into subtypes by performing a consensus clustering analysis. The correlation between the immune microenvironment of plaques and expression of angiogenesis-associated genes was also explored using the single sample gene set enrichment analysis method and the CIBERSORT algorithm. We identified hub angiogenesis-associated genes showing similar expression patterns throughout plaque adverse progression, and constructed a prediction model using the random forest algorithm. Receiver operating curves were constructed to evaluate efficacy in identification of intraplaque hemorrhage in a plaque. Our results suggest that heterogeneity of angiogenesis-related genes may promote the malignant development of plaques and cause plaque rupture. In conclusion, we propose a model based on expression of angiogenesis-related genes to predict the risk of plaque rupture.

Porous gelatin microspheres implanted with adipose mesenchymal stromal cells promote angiogenesis via protein kinase B/endothelial nitric oxide synthase signaling pathway in bladder reconstruction

BACKGROUND AIMS

Cell failure and angiogenesis are the key to bladder wall regeneration. Three-dimensional (3D) culture using porous gelatin microspheres (GMs) as a vehicle promotes stem cell proliferation and improves the paracrine capacity of cells. This study aimed to evaluate the therapeutic potential of GMs constructed from adipose-derived mesenchymal stromal cells (ADSCs) (ADSC-GMs) combined with bladder acellular matrix (BAM) in tissue-engineered bladders.

METHODS

Isolation of ADSCs, flow cytometry, scanning electron microscopy and cell counting kit-8, β-galactosidase and enzyme-linked immunosorbent assays were performed in vitro to compare two-dimensional (2D) and 3D cultures. In the in vivo study, male Sprague-Dawley rats were randomly divided into three groups: the BAM replacement alone (BAM) group, ADSCs grown on BAM in replacement (ADSC) group and ADSC-GMs combined with BAM followed by replacement (ADSC-GM) group. Bladder function assessed by urodynamics after 12 weeks of bladder replacement, and the rats were sacrificed at 4 and 12 weeks for further experiments.

RESULTS

The in vitro results showed that GM culture promoted ADSC proliferation, inhibited apoptosis and delayed senescence compared with those in the 2D culture. In addition, ADSC-GMs increased the secretion of the angiogenic factors vascular endothelial growth factor, platelet-derived growth factor-BB, and basal fibroblast growth factor. In vivo experiments revealed that ADSC-GMs adhered to the BAM for longer than ADSCs. Moreover, ADSC-GMs significantly promoted the regeneration of bladder vessels and smooth muscle, thereby facilitating the recovery of bladder function. The expression of phosphorylated protein kinase B (AKT) and phosphorylated endothelial nitric oxide synthase (eNOS) was significantly greater in the ADSC-GMs group compared with the BAM and ADSCs groups.

CONCLUSIONS

ADSC-GMs increased retention of ADSCs on the BAM, thereby promoting the regeneration and functional recovery of the bladder tissue. ADSC-GMs promoted angiogenesis by activating the AKT/eNOS pathway.

Mechanistic insights into the alterations and regulation of the AKT signaling pathway in diabetic retinopathy

In the early stages of diabetic retinopathy (DR), diabetes-related hyperglycemia directly inhibits the AKT signaling pathway by increasing oxidative stress or inhibiting growth factor expression, which leads to retinal cell apoptosis, nerve proliferation and fundus microvascular disease. However, due to compensatory vascular hyperplasia in the late stage of DR, the vascular endothelial growth factor (VEGF)/phosphatidylinositol 3 kinase (PI3K)/AKT cascade is activated, resulting in opposite levels of AKT regulation compared with the early stage. Studies have shown that many factors, including insulin, insulin-like growth factor-1 (IGF-1), VEGF and others, can regulate the AKT pathway. Disruption of the insulin pathway decreases AKT activation. IGF-1 downregulation decreases the activation of AKT in DR, which abrogates the neuroprotective effect, upregulates VEGF expression and thus induces neovascularization. Although inhibiting VEGF is the main treatment for neovascularization in DR, excessive inhibition may lead to apoptosis in inner retinal neurons. AKT pathway substrates, including mammalian target of rapamycin (mTOR), forkhead box O (FOXO), glycogen synthase kinase-3 (GSK-3)/nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear factor kappa-B (NF-κB), are a research focus. mTOR inhibitors can delay or prevent retinal microangiopathy, whereas low mTOR activity can decrease retinal protein synthesis. Inactivated AKT fails to inhibit FOXO and thus causes apoptosis. The GSK-3/Nrf2 cascade regulates oxidation and inflammation in DR. NF-κB is activated in diabetic retinas and is involved in inflammation and apoptosis. Many pathways or vital activities, such as the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) and mitogen-activated protein kinase (MAPK) signaling pathways, interact with the AKT pathway to influence DR development. Numerous regulatory methods can simultaneously impact the AKT pathway and other pathways, and it is essential to consider both the connections and interactions between these pathways. In this review, we summarize changes in the AKT signaling pathway in DR and targeted drugs based on these potential sites.

Senso-immunology: The Emerging Connection between Pain and Immunity

The sensory and immune systems have been studied independently for a long time, whereas the interaction between the two has received little attention. We have carried out research to understand the interaction between the sensory and immune systems and have found that inflammation and bone destruction caused by fungal infection are suppressed by nociceptors. Furthermore, we have elucidated the molecular mechanism whereby fungal receptors are expressed on nociceptors and skin epithelium, how they cooperate to generate fungal pain, and how colitis and bone metabolism are regulated by mechanosensors expressed on the gut epithelium. Recently, we found that nociceptors prevent septic death by inhibiting microglia via nociceptor-derived hormones. This review summarizes our current state of knowledge on pain biology and outlines the mechanisms whereby pain and immunity interact. Our findings indicate that the sensory and immune systems share a variety of molecules and interact with each other to regulate our pathological and homeostatic conditions. This prompted us to advocate the interdisciplinary science named "senso-immunology," and this emerging field is expected to generate new ideas in both physiology and immunology, leading to the development of novel drugs to treat pain and inflammation.

Mesenchymal Stem Cell Derived Exosomes Therapy in Diabetic Wound Repair

Nowadays, refractory diabetic wounds cause a worldwide medical burden. Mesenchymal stem cells derived exosomes (MSC-Exos) show promise as a solid alternative to existing therapeutics in the latest researches, since MSC-Exos share similar biologic activity but less immunogenicity when compared with MSCs. To facilitate further understanding and application, it is essential to summarize the current progress and limitations of MSC-Exos in the treatment of diabetic wounds. In this review, we introduce the effects of different MSC-Exos on diabetic wounds according to their origins and contents and discuss the specific experimental conditions, target wound cells/pathways, and specific mechanisms. In addition, this paper focuses on the combination of MSC-Exos and biomaterials, which improves the efficacy and utilization of MSC-Exos therapy. Together, exosome therapy has high clinical value and application prospects, both in its role and in combination with biomaterials, while novel drugs or molecules loaded into exosomes as carriers targeting wound cells will be development trends.

Arsenic exposure promotes the emergence of cardiovascular diseases

A large number of studies conducted in the past decade 2010-2020 refer to the impact of arsenic (As) exposure on cardiovascular risk factors. The arsenic effect on humans is complex and mainly depends on the varying individual susceptibilities, its numerous toxic expressions and the variation in arsenic metabolism between individuals. In this review we present relevant data from studies which document the association of arsenic exposure with various biomarkers, the effect of several genome polymorphisms on arsenic methylation and the underling molecular mechanisms influencing the cardiovascular pathology. The corresponding results provide strong evidence that high and moderate-high As intake induce oxidative stress, inflammation and vessel endothelial dysfunction that are associated with increased risk for cardiovascular diseases (CVDs) and in particular hypertension, myocardial infarction, carotid intima-media thickness and stroke, ventricular arrhythmias and peripheral arterial disease. In addition, As exposure during pregnancy implies risks for blood pressure abnormalities among infants and increased mortality rates from acute myocardial infarction during early adulthood. Low water As concentrations are associated with increased systolic, diastolic and pulse pressure, coronary heart disease and incident stroke. For very low As concentrations the relevant studies are few. They predict a risk for myocardial infarction, stroke and ischemic stroke and incident CVD, but they are not in agreement regarding the risk magnitude.

Cell-free therapy based on stem cell-derived exosomes: A promising approach for wound healing

There are several successive and overlapping phases in wound healing as a complex process. By the disruption of each of thesephases, chronic non-healing wounds are resultant. Despite the present soothing surgeries, standard wound dressings, and topical gels, the wound is often not completelyclosed. Today, stem cells have attracted a huge deal of attention therapeutically and pharmaceutically considering their unique features. However, they have some restrictions. Moreover, it is hoped to eliminate the limitations of cellular therapies based on their derivatives known as exosomes. Exosomes are extracellular vesicles secreted from cells. They have a diameter of almost 30-150 nm and miRNAs, mRNAs, and proteins that are possibly different from the source cell are included in exosomal contents. Such nanovesicles have a key role in the intercellular communication of pathological and physiological procedures. Exosome-based therapy is a new significant method for wound healing. By exosomes effects, wound management may be improved and a new therapeutic model may be highlighted for cell-free therapies with reduced side effects for the wound repair. This article is protected by copyright. All rights reserved.

Efficacy of leupeptin in treating ischemia in a rat hind limb model

Prolonged tourniquet use can lead to tissue ischemia and can cause progressive muscle and nerve injuries. Such injuries are accompanied by calpain activation and subsequent Wallerian-like degeneration. Several known inhibitors, including leupeptin, are known to impede the activity of calpain and associated tissue damage. We hypothesize that employment of leupeptin in a rat model of prolonged hind limb ischemia can mitigate muscle and nerve injuries. Sprague-Dawley rats (n = 10) weighing between 300-400 g were employed in this study. Their left hind limbs were subjected to blood flow occlusion for a period of 2-h using a neonatal blood pressure cuff. Five rats were given twice weekly intramuscular leupeptin injections, while the other five received saline. After 2 weeks, the animals were euthanized, their sciatic nerves and gastrocnemius muscles were harvested, fixed, stained, and analyzed using NIH Image J software. The administration of leupeptin resulted in larger gastrocnemius muscle fiber cross-sectional areas for the right (non-tourniquet applied) hindlimb as compared to that treated with the saline (p = 0.0110). However, no statistically significant differences were found between these two groups for the injured left hindlimb (p = 0.1440). With regards to the sciatic nerve cross-sectional areas and sciatic functional index, no differences were detected between the leupeptin and control treated groups for both the healthy and injured hindlimbs. This research provides new insights on how to employ leupeptin to inhibit the degenerative effects of calpain and preserve tissues following ischemia resulting from orthopedic or plastic surgery procedures.

BuyangHuanwu Decoction attenuates cerebral vasospasm caused by subarachnoid hemorrhage in rats via PI3K/AKT/eNOS axis

The ancient Chinese remedy BuyangHuanwu Decoction (BHD) is used to treat qi deficit and blood stasis conditions. This work investigated the effect of BHD on cerebral vasospasm (CVS) caused by subarachnoid hemorrhage (SAH). Rats were randomly assigned into four groups: control group, SAH group, SAH + BHD [13 g/(kg day)] group, and SAH + BHD [26 g/(kg day)] group. The Garcia neurological scoring scale was used to assess neurological dysfunction. Hematoxylin and eosin stains were used to determine the extent of vasospasm by measuring the diameter of the basilar artery. Western blot was used to measure the concentrations of phosphoinositide 3-kinase (PI3K), AKT, and phospho-AKT expression levels. RT-PCR was used to determine PI3K and AKT RNA expressions. Immunohistochemistry and enzyme-linked immunosorbent assay were used to measure levels of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO), respectively, in cerebrospinal fluid. BHD treatment ameliorated CVS and mitigated neurological dysfunction after SAH. Furthermore, the findings suggest that NO concentration was increased through the activation of classical PI3K/AKT signaling and the eNOS pathway. Thus, BHD showed multifaceted roles in preventing damage via decreasing vasospasm and improving neurological impairments caused by CVS after SAH.

GABA Receptor Agonists Protect From Excitotoxic Damage Induced by AMPA in Oligodendrocytes

Oligodendrocytes are the myelin forming cells of the central nervous system, and their vulnerability to excitotoxicity induced by glutamate contributes to the pathogenesis of neurological disorders including brain ischemia and neurodegenerative diseases, such as multiple sclerosis. In addition to glutamate receptors, oligodendrocytes express GABA receptors (GABAR) that are involved in their survival and differentiation. The interactions between glutamate and GABAergic systems are well documented in neurons, under both physiological and pathological conditions, but this potential crosstalk in oligodendrocytes has not been studied in depth. Here, we evaluated the protective effect of GABAR agonists, baclofen (GABAB) and muscimol (GABAA), against AMPA-induced excitotoxicity in cultured rat oligodendrocytes. First, we observed that both baclofen and muscimol reduced cell death and caspase-3 activation after AMPA insult, proving their oligoprotective potential. Interestingly, analysis of the cell-surface expression of calcium-impermeable GluR2 subunits in oligodendrocytes revealed that GABAergic agonists significantly reverted GluR2 internalization induced by AMPA. We determined that baclofen and muscimol also impaired AMPA-induced intracellular calcium increase and subsequent mitochondrial membrane potential alteration, ROS generation, and calpain activation. However, AMPA-triggered activation of Src, Akt, JNK and CREB was not affected by baclofen or muscimol. Overall, our results suggest that GABAR activation initiates alternative molecular mechanisms that attenuate AMPA-mediated apoptotic excitotoxicity in oligodendrocytes by interfering with expression of GluR subunits in membranes and with calcium-dependent intracellular signaling pathways. Together, these findings provide evidence of GABAR agonists as potential oligodendroglial protectants in central nervous system disorders.

Mechanosensitive channel Piezo1 is required for pulmonary artery smooth muscle cell proliferation

Concentric pulmonary vascular wall thickening due partially to increased pulmonary artery (PA) smooth muscle cell (PASMC) proliferation contributes to elevating pulmonary vascular resistance (PVR) in patients with pulmonary hypertension (PH). Although pulmonary vasoconstriction may be an early contributor to increasing PVR, the transition of contractile PASMCs to proliferative PASMCs may play an important role in the development and progression of pulmonary vascular remodeling in PH. A rise in cytosolic Ca2+ concentration ([Ca2+]cyt) is a trigger for PASMC contraction and proliferation. Here, we report that upregulation of Piezo1, a mechanosensitive cation channel, is involved in the contractile-to-proliferative phenotypic transition of PASMCs and potential development of pulmonary vascular remodeling. By comparing freshly isolated PA (contractile PASMCs) and primary cultured PASMCs (from the same rat) in a growth medium (proliferative PASMCs), we found that Piezo1, Notch2/3, and CaSR protein levels were significantly higher in proliferative PASMCs than in contractile PASMCs. Upregulated Piezo1 was associated with an increase in expression of PCNA, a marker for cell proliferation, whereas downregulation (with siRNA) or inhibition (with GsMTx4) of Piezo1 attenuated PASMC proliferation. Furthermore, Piezo1 in the remodeled PA from rats with experimental PH was upregulated compared with PA from control rats. These data indicate that PASMC contractile-to-proliferative phenotypic transition is associated with the transition or adaptation of membrane channels and receptors. Upregulated Piezo1 may play a critical role in PASMC phenotypic transition and PASMC proliferation. Upregulation of Piezo1 in proliferative PASMCs may likely be required to provide sufficient Ca2+ to assure nuclear/cell division and PASMC proliferation, contributing to the development and progression of pulmonary vascular remodeling in PH.

Dracorhodin Perchlorate Regulates the Expression of Inflammatory Cytokines through the TLR4 Pathway and Improves Skin Wound Healing in Diabetic Rats

Background

Dragon's blood is a natural medicine with hemostatic and blood-activating effects and is used to promote wound healing. Dracorhodin perchlorate (DP) is a stable form of dracarhod and is used as a substitute for cochinchinenin. DP promotes the proliferation of rat fibroblasts and promotes wound healing in rats.

Methods

DP ointment (0.2 mg/mL) was applied to the skin wounds of nondiabetic and diabetic rats, and the skin of the wound was collected. Wound healing rate, H&E staining, Masson staining, TLR4 pathway, related inflammatory factors, nitric oxide synthase, and so forth were detected.

Results

DP treatment alleviated the prolonged inflammatory cell infiltration time and the increase in the TLR4 pathway and inflammatory factors caused by diabetes. DP also promoted wound healing by increasing eNOS protein expression and NO content in the later stage of wound healing.

Conclusion

DP promotes wound healing in diabetic rats by regulating the TLR4 pathway and related inflammatory factors. Therefore, adjuvant treatment of DP can be developed for diabetic wound healing.

Calpain as a therapeutic target in cancer

INTRODUCTION

Calpain-1 and calpain-2 are prototypical classical isoforms of the calpain family of calcium-activated cysteine proteases. Their substrate proteins participate in a wide range of cellular processes, including transcription, survival, proliferation, apoptosis, migration, and invasion. Dysregulated calpain activity has been implicated in tumorigenesis, suggesting that calpains may be promising therapeutic targets.

AREAS COVERED

This review covers clinical and basic research studies implicating calpain-1 and calpain-2 expression and activity in tumorigenesis and metastasis. We highlight isoform specific functions and provide an overview of substrates and cancer-related signalling pathways affected by calpain-mediated proteolytic cleavage. We also discuss efforts to develop clinically relevant calpain specific inhibitors and spotlight the challenges facing inhibitor development.

EXPERT OPINION

Rationale for targeting calpain-1 and calpain-2 in cancer is supported by pre-clinical and clinical studies demonstrating that calpain inhibition has the potential to attenuate carcinogenesis and block metastasis of aggressive tumors. The wide range of substrates and cleavage products, paired with inconsistencies in model systems, underscores the need for more complete understanding of physiological substrates and how calpain cleavage alters their function in cellular processes. The development of isoform specific calpain inhibitors remains an important goal with therapeutic potential in cancer and other diseases.

Myofibre injury induces capillary disruption and regeneration of disorganized microvascular networks

Injury to skeletal muscle disrupts myofibres and their microvascular supply. While the regeneration of myofibres is well described, little is known of how the microcirculation is affected by skeletal muscle injury or its recovery during regeneration. Nevertheless, the microvasculature must also recover to restore skeletal muscle function. We aimed to define the nature of microvascular damage and time course of repair during muscle injury and regeneration induced by the myotoxin BaCl₂ . To test the hypothesis that microvascular disruption occurred secondary to myofibre injury, isolated microvessels were exposed to BaCl₂ or the myotoxin was injected into the gluteus maximus (GM) muscle of mice. In isolated microvessels, BaCl₂ depolarized smooth muscle cells (SMCs) and endothelial cells while increasing intracellular calcium in SMCs but did not elicit death of either cell type. At 1 day post-injury (dpi) of the GM, capillary fragmentation coincided with myofibre degeneration while arteriolar and venular networks remained intact; neutrophil depletion before injury did not prevent capillary damage. Perfused capillary networks reformed by 5 dpi in association with more terminal arterioles and were dilated through 10 dpi. With no change in microvascular area or branch point number in regenerating capillary networks, fewer capillaries aligned with myofibres and were no longer organized into microvascular units. By 21 dpi, capillary orientation and microvascular unit organization were no longer different from uninjured GM. We conclude that following their disruption secondary to myofibre damage, capillaries regenerate as disorganized networks that remodel into microvascular units as regenerated myofibres mature. KEY POINTS: Skeletal muscle regenerates after injury; however, the nature of microvascular damage and repair is poorly understood. Here, the myotoxin BaCl₂ , a standard experimental method of acute skeletal muscle injury, was used to investigate the response of the microcirculation to local injury of intact muscle. Intramuscular injection of BaCl₂ induced capillary fragmentation with myofibre degeneration; arteriolar and venular networks remained intact. Direct exposure to BaCl₂ did not kill microvascular endothelial cells or smooth muscle cells. Dilated capillary networks reformed by 5 days post-injury (dpi) in association with more terminal arterioles. Capillary orientation remained disorganized through 10 dpi. Capillaries realigned with myofibres and reorganized into microvascular units by 21 dpi, which coincides with the recovery of vasomotor control and maturation of nascent myofibres. Skeletal muscle injury disrupts its capillary supply secondary to myofibre degeneration. Reorganization of regenerating microvascular networks accompanies the recovery of blood flow regulation.

Transcriptional and Epigenetic Bioinformatic Analysis of Claudin-9 Regulation in Gastric Cancer

Gastric cancer is a heterogeneous disease that represents 5% to 10% of all new cancer cases worldwide. Advances in histological diagnosis and the discovery of new genes have admitted new genomic classifications. Nevertheless, the bioinformatic analysis of gastric cancer databases has favored the detection of specific differentially expressed genes with biological significance. Claudins, a family of proteins involved in tight junction physiology, have emerged as the key regulators of cellular processes, such as growth, proliferation, and migration, associated with cancer progression. The expression of Claudin-9 in the gastric cancer tissue has been linked to poor prognosis, however, its transcriptional and epigenetic regulations demand a more comprehensive analysis. Using the neural network promoter prediction, TransFact, Uniprot-KB, Expasy-SOPMA, protein data bank, proteomics DB, Interpro, BioGRID, String, and the FASTA protein sequence databases and software, we found the following: (1) the promoter sequence has an unconventional structure, including different transcriptional regulation elements distributed throughout it, (2) GATA 4, GATA 6, and KLF5 are the key regulators of Claudin-9 expression, (3) Oct1, NF-κB, AP-1, c-Ets-1, and HNF-3β have the higher binding affinity to the CLDN9 promoter, (4) Claudin-9 interacts with cell differentiation and development proteins, (5) CLDN9 is highly methylated, and (6) Claudin-9 expression is associated with poor survival. In conclusion, Claudin-9 is a protein that should be considered a diagnostic marker as its gene promoter region binds to the transcription factors associated with the deregulation of cell control, enhanced cell proliferation, and metastasis.

Natural Products: A Promising Therapeutics for Targeting Tumor Angiogenesis

Tumor-associated angiogenesis is a key target for anti-cancer therapy. The imbalance between pro-angiogenic and anti-angiogenic signals elicited by tumor cells or tumor microenvironment always results in activating "angiogenic switch". Tumor angiogenesis functions in multi-aspects of tumor biology, including endothelial cell apoptosis, tumor metastasis, and cancer stem cell proliferation. Numerous studies have indicated the important roles of inexpensive and less toxic natural products in targeting tumor angiogenesis-associated cytokines and apoptotic signaling pathways. Our current knowledge of tumor angiogenesis is based mainly on experiments performed on cells and animals, so we summarized the well-established models for angiogenesis both in vitro and in vivo. In this review, we classified and summarized the anti-angiogenic natural agents (Polyphenols, Polysaccharides, Alkaloids, Terpenoids, Saponins) in targeting various tumor types according to their chemical structures at present, and discussed the mechanistic principles of these natural products on regulating angiogenesis-associated cytokines and apoptotic signaling pathways. This review is to help understanding the recent progress of natural product research for drug development on anti-tumor angiogenesis.

Calpain-Mediated Mitochondrial Damage: An Emerging Mechanism Contributing to Cardiac Disease

Calpains belong to the family of calcium-dependent cysteine proteases expressed ubiquitously in mammals and many other organisms. Activation of calpain is observed in diseased hearts and is implicated in cardiac cell death, hypertrophy, fibrosis, and inflammation. However, the underlying mechanisms remain incompletely understood. Recent studies have revealed that calpains target and impair mitochondria in cardiac disease. The objective of this review is to discuss the role of calpains in mediating mitochondrial damage and the underlying mechanisms, and to evaluate whether targeted inhibition of mitochondrial calpain is a potential strategy in treating cardiac disease. We expect to describe the wealth of new evidence surrounding calpain-mediated mitochondrial damage to facilitate future mechanistic studies and therapy development for cardiac disease.

Mechanosensitive Piezo1 in endothelial cells promotes angiogenesis to support bone fracture repair

Piezo1, a calcium-permeable non-selective cationic channel that senses mechanical stimulation in multicellular organisms, mediates various biological processes, including angiogenesis. The supply of nutrients and oxygen through newly formed blood vessels at the fractured lesion is critical for bone fracture repair. The elucidation of the underlying mechanisms involved in angiogenesis and bone repair can aid in improving fracture healing. Here, mice with endothelial cell-specific deletion of Piezo1 channels were used to examine the role of Piezo1 in the initiation of fracture healing. The expression and distribution of Piezo1 was explored in the vasculature of the bone. The deletion of endothelial Piezo1 resulted in impaired bone fracture repair, downregulation of calcium-activated proteolytic calpain activity during vascularization, inhibition of osteoblast maturation and ossification, downregulation of phosphorylated PI3K-AKT, and impaired Notch signaling during bone fracture union. These findings indicated that Piezo1 protein is a potential target for enhancing bone regeneration and treating delayed or nonunion bone fractures.

Cryptotanshinone enhances wound healing in type 2 diabetes with modulatory effects on inflammation, angiogenesis and extracellular matrix remodelling

CONTEXT

Cryptotanshinone (CT) is a diterpene quinone compound from Salvia miltiorrhiza Bge. Labiatae has been widely used in cardio-cerebral vascular diseases, which could be potentially effective in treating diabetic wounds.

OBJECTIVE

This study evaluates the wound healing activity of CT by employing an excisional wound splinting model in db/db mice.

MATERIALS AND METHODS

Wounds were induced at the dorsum of non-diabetic (db/+) and diabetic (db/db) mice and treated with sodium carboxymethyl cellulose (CMC-Na) or 300 mg/kg/d CT for 16 days. Wound closure was measured every two days. Body weight, fasting blood glucose, re-epithelialization, granulation, leukocyte infiltration, capillary density, collagen deposition and expressions of CXCL1, CXCL2, VEGF, Ang-1, p-eNOS, eNOS, α-SMA, MMP2 and MMP9 were analysed. Expression of VEGF and tube formation was measured in vitro with human umbilical vein endothelial cells (HUVECs).

RESULTS

CT significantly accelerated rate of wound closure, as the contraction ratio increased from 68% (non-treated group) to 83% (CT-treated group) at days 16 post-injury. A significant increase was observed in re-epithelialization and granulation tissue formation. Mechanistically, CT suppressed leukocyte infiltration and CXCL1 and CXCL2 expression. CT treatment also increased blood vessel density and expression level of VEGF, Ang-1 and p-eNOS. In vitro, CT boosted expression of VEGF and tube formation of endothelial cells. Moreover, extracellular matrix (ECM) remodelling was enhanced by CT via promoting fibroblast transformation and inhibiting MMP2 and MMP9.

CONCLUSIONS

Our study provides evidence that CT could be developed as a potential therapeutic agent for the treatment of chronic diabetic wound healing.

Exosomes derived from atorvastatin-pretreated MSC accelerate diabetic wound repair by enhancing angiogenesis via AKT/eNOS pathway

Background

Mesenchymal stem cell (MSC)-derived exosomes emerge as promising candidates for treating delayed wound healing in diabetes due to the promotion of angiogenesis. Preconditioned MSC with chemical or biological factors could possibly enhance the biological activities of MSC-derived exosomes. The purpose of this research focused on whether exosomes derived from the bone marrow MSC (BMSC) pretreated with atorvastatin (ATV), could exhibit better pro-angiogenic ability in diabetic wound healing or not and its underlying molecular mechanism.

Methods

We isolated exosomes from non-pretreated BMSC (Exos) and ATV pretreated BMSC (ATV-Exos) and evaluated their characterization by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and Western blotting. In vivo, we made full-thickness skin defects in streptozotocin (STZ)-induced diabetic rats and the defects received multiple-point injection with PBS, Exos, or ATV-Exos. Two weeks later, histological analysis was conducted to evaluate the impact of different treatments on wound healing and the neovascularization was measured by micro-CT. In vitro, cell proliferation, migration, tube formation, and vascular endothelial growth factor (VEGF) secretion were measured in human umbilical vein endothelial cells (HUVEC). The role of miRNAs and AKT/eNOS signaling pathway in the promoted angiogenesis of ATV-Exos were assessed with their inhibitors.

Results

No significant difference in morphology, structure, and concentration was observed between ATV-Exos and Exos. In STZ-induced diabetic rats, ATV-Exos exhibited excellent abilities in facilitating the wound regeneration by promoting the formation of blood vessels compared with Exos without influencing liver and kidney function. Meanwhile, ATV-Exos promoted the proliferation, migration, tube formation, and VEGF level of endothelial cells in vitro. And AKT/eNOS pathway was activated by ATV-Exos and the pro-angiogenic effects of ATV-Exo were attenuated after the pathway being blocked. MiR-221-3p was upregulated by ATV-Exos stimulation, and miR-221-3p inhibitor suppressed the pro-angiogenesis effect of ATV-Exos.

Conclusions

Exosomes originated from ATV-pretreated MSCs might serve as a potential strategy for the treatment of diabetic skin defects through enhancing the biological function of endothelial cells via AKT/eNOS pathway by upregulating the miR-221-3p.

Targeted inhibition of endothelial calpain delays wound healing by reducing inflammation and angiogenesis

Wound healing is a multistep phenomenon that relies on complex interactions between various cell types. Calpains are a well-known family of calcium-dependent cysteine proteases that regulate several processes, including cellular adhesion, proliferation, and migration, as well as inflammation and angiogenesis. CAPNS1, the common regulatory subunit of Calpain-1 and 2, is indispensable for catalytic subunit stabilization and activity. Calpain inhibition has been shown to reduce organ damage in various disease models. Here, we report that endothelial calpain-1/2 is crucially involved in skin wound healing. Using a mouse genetic model where Capns1 is deleted only in endothelial cells, we showed that calpain-1/2 disruption is associated with reduced injury-activated inflammation, reduced CD31⁺ blood vessel density, and delayed wound healing. Moreover, in cultured HUVECs, inhibition of calpain reduced TNF-α-induced proliferation, migration, and tube formation. Deletion of Capns1 was associated with elevated levels of IκB and downregulation of β-catenin expression in endothelial cells. These observations delineate a novel mechanistic role for calpain in the crosstalk between inflammation and angiogenesis during skin repair.

Barium chloride injures myofibers through calcium-induced proteolysis with fragmentation of motor nerves and microvessels

Background

Local injection of BaCl₂ is an established model of acute injury to study the regeneration of skeletal muscle. However, the mechanism by which BaCl₂ causes muscle injury is unresolved. Because Ba²⁺ inhibits K⁺ channels, we hypothesized that BaCl₂ induces myofiber depolarization leading to Ca²⁺ overload, proteolysis, and membrane disruption. While BaCl₂ spares resident satellite cells, its effect on other tissue components integral to contractile function has not been defined. We therefore asked whether motor nerves and microvessels, which control and supply myofibers, are injured by BaCl₂ treatment.

Methods

The intact extensor digitorum longus (EDL) muscle was isolated from male mice (aged 3–4 months) and irrigated with physiological salt solution (PSS) at 37 °C. Myofiber membrane potential (V_m) was recorded using sharp microelectrodes while intracellular calcium concentration ([Ca²⁺]_i) was evaluated with Fura 2 dye. Isometric force production of EDL was measured in situ, proteolytic activity was quantified by calpain degradation of αII-spectrin, and membrane disruption was marked by nuclear staining with propidium iodide (PI). To test for effects on motor nerves and microvessels, tibialis anterior or gluteus maximus muscles were injected with 1.2% BaCl₂ (50–75 μL) in vivo followed by immunostaining to evaluate the integrity of respective tissue elements post injury. Data were analyzed using Students t test and analysis of variance with P ≤ 0.05 considered statistically significant.

Results

Addition of 1.2% BaCl₂ to PSS depolarized myofibers from − 79 ± 3 mV to − 17 ± 7 mV with a corresponding rise in [Ca²⁺]_i; isometric force transiently increased from 7.4 ± 0.1 g to 11.1 ± 0.4 g. Following 1 h of BaCl₂ exposure, 92 ± 3% of myonuclei stained with PI (vs. 8 ± 3% in controls) with enhanced cleavage of αII-spectrin. Eliminating Ca²⁺ from PSS prevented the rise in [Ca²⁺]_i and ameliorated myonuclear staining with PI during BaCl₂ exposure. Motor axons and capillary networks appeared fragmented within 24 h following injection of 1.2% BaCl₂ and morphological integrity deteriorated through 72 h.

Conclusions

BaCl₂ injures myofibers through depolarization of the sarcolemma, causing Ca²⁺ overload with transient contraction, leading to proteolysis and membrane rupture. Motor innervation and capillarity appear disrupted concomitant with myofiber damage, further compromising muscle integrity.

Mechanism and Consequences of The Impaired Hif-1α Response to Hypoxia in Human Proximal Tubular HK-2 Cells Exposed to High Glucose

Renal hypoxia and loss of proximal tubular cells (PTC) are relevant in diabetic nephropathy. Hypoxia inhibits hypoxia-inducible factor-1α (HIF-1α) degradation, which leads to cellular adaptive responses through HIF-1-dependent activation of gene hypoxia-responsive elements (HRE). However, the diabetic microenvironment represses the HIF-1/HRE response in PTC. Here we studied the mechanism and consequences of impaired HIF-1α regulation in human proximal tubular HK-2 cells incubated in hyperglycemia. Inhibition at different levels of the canonical pathway of HIF-1α degradation did not activate the HIF-1/HRE response under hyperglycemia, except when proteasome was inhibited. Further studies suggested that hyperglycemia disrupts the interaction of HIF-1α with Hsp90, a known cause of proteasomal degradation of HIF-1α. Impaired HIF-1α regulation in cells exposed to hyperglycemic, hypoxic diabetic-like milieu led to diminished production of vascular endothelial growth factor-A and inhibition of cell migration (responses respectively involved in tubular protection and repair). These effects, as well as impaired HIF-1α regulation, were reproduced in normoglycemia in HK-2 cells incubated with microparticles released by HK-2 cells exposed to diabetic-like milieu. In summary, these results highlight the role of proteasome-dependent mechanisms of HIF-1α degradation on diabetes-induced HK-2 cells dysfunction and suggest that cell-derived microparticles may mediate negative effects of the diabetic milieu on PTC.

Regulation of calpain 2 expression by miR-223 and miR-145

Calpain 2 (CAPN2) is a Ca²⁺-dependent cysteine-protease that is involved in different cellular processes. Despite its important role, little is known about how CAPN2 expression is regulated. This study addressed the potential regulation of CAPN2 by microRNAs (miRNAs) in human endothelial cells. Two miRNAs were found to regulate CAPN2 expression by two distinct mechanisms, one direct and the other indirect. MiR-223 directly targeted CAPN2 by binding to the CAPN2 3'-untranslated region. Mir-223 overexpression decreased CAPN2 protein levels in cultured cells and in mice miR-223 antagonism led to an increase in CAPN2 protein in lung tissue. MiR-145 overexpression also decreased CAPN2 expression but did not affect a CAPN2 luciferase construct, indicating that the effect was indirect. MiR-145 targets histone deacetylase (HDAC) 2, and HDAC inhibition transcriptionally regulated CAPN2 expression by hyperacetylation of the promoter of CAPN2 gene and a subsequent decrease in polymerase 2 binding. Indeed, down regulation of HDAC2 by miR-145 not only decreased CAPN2 protein expression and calpain activity, but also protected paxillin against calpain-dependent degradation. Thus, protein levels of CAPN2 are regulated by miR-223, acting directly on the 3'-untranslated region as well as by miR-145, which acts via an increase in HDAC2. ENZYMES: Calpain 2 (EC 3.4.22.53), histone deacetylase 2 (EC 3.5.1.98).

Regulation of Stress Granule Formation by Inflammation, Vascular Injury, and Atherosclerosis

OBJECTIVE

Stress granules (SGs) are dynamic cytoplasmic aggregates containing mRNA, RNA-binding proteins, and translation factors that form in response to cellular stress. SGs have been shown to contribute to the pathogenesis of several human diseases, but their role in vascular diseases is unknown. This study shows that SGs accumulate in vascular smooth muscle cells (VSMCs) and macrophages during atherosclerosis. Approach and Results: Immunohistochemical analysis of atherosclerotic plaques from LDLR^-/- mice revealed an increase in the stress granule-specific markers Ras-G3BP1 (GTPase-activating protein SH3 domain-binding protein) and PABP (poly-A-binding protein) in intimal macrophages and smooth muscle cells that correlated with disease progression. In vitro, PABP+ and G3BP1+ SGs were rapidly induced in VSMC and bone marrow-derived macrophages in response to atherosclerotic stimuli, including oxidized low-density lipoprotein and mediators of mitochondrial or oxidative stress. We observed an increase in eIF2α (eukaryotic translation initiation factor 2-alpha) phosphorylation, a requisite for stress granule formation, in cells exposed to these stimuli. Interestingly, SG formation, PABP expression, and eIF2α phosphorylation in VSMCs is reversed by treatment with the anti-inflammatory cytokine interleukin-19. Microtubule inhibitors reduced stress granule accumulation in VSMC, suggesting cytoskeletal regulation of stress granule formation. SG formation in VSMCs was also observed in other vascular disease pathologies, including vascular restenosis. Reduction of SG component G3BP1 by siRNA significantly altered expression profiles of inflammatory, apoptotic, and proliferative genes.

CONCLUSIONS

These results indicate that SG formation is a common feature of the vascular response to injury and disease, and that modification of inflammation reduces stress granule formation in VSMC.

Endothelial Ca2+ Signaling, Angiogenesis and Vasculogenesis: just What It Takes to Make a Blood Vessel

It has long been known that endothelial Ca²⁺ signals drive angiogenesis by recruiting multiple Ca²⁺-sensitive decoders in response to pro-angiogenic cues, such as vascular endothelial growth factor, basic fibroblast growth factor, stromal derived factor-1α and angiopoietins. Recently, it was shown that intracellular Ca²⁺ signaling also drives vasculogenesis by stimulation proliferation, tube formation and neovessel formation in endothelial progenitor cells. Herein, we survey how growth factors, chemokines and angiogenic modulators use endothelial Ca²⁺ signaling to regulate angiogenesis and vasculogenesis. The endothelial Ca²⁺ response to pro-angiogenic cues may adopt different waveforms, ranging from Ca²⁺ transients or biphasic Ca²⁺ signals to repetitive Ca²⁺ oscillations, and is mainly driven by endogenous Ca²⁺ release through inositol-1,4,5-trisphosphate receptors and by store-operated Ca²⁺ entry through Orai1 channels. Lysosomal Ca²⁺ release through nicotinic acid adenine dinucleotide phosphate-gated two-pore channels is, however, emerging as a crucial pro-angiogenic pathway, which sustains intracellular Ca²⁺ mobilization. Understanding how endothelial Ca²⁺ signaling regulates angiogenesis and vasculogenesis could shed light on alternative strategies to induce therapeutic angiogenesis or interfere with the aberrant vascularization featuring cancer and intraocular disorders.

Calpain system protein expression and activity in ovarian cancer

Purpose

Expression of members of the calpain system are associated with clinical outcome of patients with, amongst others, breast and ovarian cancers, with calpain-2 expression in ovarian cancer being implicated in chemo-resistance and survival. This study aimed, using a large patient cohort and in vitro models, to verify its importance and further investigate the role in ovarian cancer chemoresponse.

Methods

Calpain-1, calpain-2, calpain-4 and calpastatin expression were evaluated in primary ovarian carcinomas (n = 575) by immunohistochemistry. Protein expression was assessed, via western blotting, in five ovarian cancer cell lines with various sensitivities towards cisplatin/carboplatin. In vitro calpain activity was inhibited by calpeptin treatment to assess changes in platinum sensitivity by proliferation assay, with expression of genes associated with epithelial–mesenchymal transition being examined by RT² Profiler™ PCR Array.

Results

The current study confirmed previous data that high calpain-2 expression is associated with poor overall survival (P = 0.026) and that calpain-1 was not associated with overall survival or progression-free survival. Low expression of calpastatin (P = 0.010) and calpain-4 (P = 0.003) were also associated with adverse survival. Such prognostic associations do not seem to be linked with altered tumour sensitivity towards platinum-based chemotherapy. Interestingly, low calpain-1 expression was more frequent in patients with confined tumours (stage 1) (χ² = 11.310, df = 1, P = 0.001). Calpain and calpastatin expression varied among ovarian cancer cell lines yet their expression levels were similar between chemo-sensitive cells and resistant counterparts. Moreover, calpeptin treatment did not alter cellular response to platinum-based chemotherapy or epithelial–mesenchymal transition-related gene expression.

Conclusions

The conventional calpains and calpastatin have been confirmed to play an important role in ovarian cancer; however, the precise mechanisms whereby they exert effects remain to be elucidated.

Electronic supplementary material

The online version of this article (10.1007/s00432-018-2794-2) contains supplementary material, which is available to authorized users.

Endothelial calpain systems orchestrate myofibroblast differentiation during wound healing

The transformation of fibroblasts to myofibroblasts plays a major role in fibrogenic responses during dermal wound healing. We show a contribution of calpain systems (intracellular regulatory protease systems) in vascular endothelial cells (ECs) to myofibroblast differentiation in wound sites. Dermal wound healing experiments in mice found that calpastatin (an endogenous inhibitor of calpains) is enriched in preexisting vessels but not in newly formed capillaries. Transgenic overexpression of calpastatin in ECs delayed wound healing in mice as well as reducing the keratinocyte layer, extracellular matrix deposition, and myofibroblast accumulation in wound sites. EC and leukocyte markers, however, remain unchanged. Calpastatin overexpression reduced the expression of genes encoding platelet-derived growth factor-B and PDGF receptor-β (PDGFR-β). Topical application of platelet-derived growth factor-BB-containing ointment to wounds accelerated healing in control mice, but calpastatin overexpression prevented this acceleration. In cultured human dermal fibroblasts, α-smooth muscle actin and PDGFR-β were up-regulated by coculturing with ECs, but this action was inhibited by suppression of EC calpain activity. EC-driven transformation of mouse dermal fibroblasts was also suppressed by calpastatin overexpression in ECs. These results suggest that endothelial calpain systems influence PDGFR-β signaling in fibroblasts, EC-driven myofibroblast differentiation, and subsequent fibrogenic responses in wounds.-Miyazaki, T., Haraguchi, S., Kim-Kaneyama, J.-R., Miyazaki, A. Endothelial calpain systems orchestrate myofibroblast differentiation during wound healing.

Characterization of the Goose CAPN3 Gene and its Expression Pattern in Muscle Tissues of Sichuan White Geese at Different Growth Stages

Calpain 3 (CAPN3), also known as p94, is associated with multiple production traits in domestic animals. However, the molecular characteristics of the CAPN3 gene and its expression profile in goose tissues have not been reported. In this study, CAPN3 cDNA of the Sichuan white goose was cloned, sequenced, and characterized. The CAPN3 full-length cDNA sequence consists of a 2,316-bp coding sequence (CDS) that encodes 771 amino acids with a molecular mass of 89,019 kDa. The protein was predicted to have no signal peptide, but several N-glycosylation, O-glycosylation, and phosphorylation sites. The secondary structure of CAPN3 was predicted to be 38.65% α-helical. Sequence alignment showed that CAPN3 of Sichuan white goose shared more than 90% amino acid sequence similarity with those of Japanese quail, turkey, helmeted guineafowl, duck, pigeon, and chicken. Phylogenetic tree analysis showed that goose CAPN3 has a close genetic relationship and small evolutionary distance with those of the birds. qRT-PCR analysis showed that in 15-day-old animals, the expression level of CAPN3 was significantly higher in breast muscle than in thigh tissues. These results serve as a foundation for further investigations of the function of the goose CAPN3 gene.

PI3K and Calcium Signaling in Cardiovascular Disease

Receptor signaling relays on intracellular events amplified by secondary and tertiary messenger molecules. In cardiomyocytes and smooth muscle cells, cyclic AMP (cAMP) and subsequent calcium (Ca²⁺) fluxes are the best characterized receptor-regulated signaling events. However, most of receptors able to modify contractility and other intracellular responses signal through a variety of other messengers, and whether these signaling events are interconnected has long remained unclear. For example, the PI3K (phosphoinositide 3-kinase) pathway connected to the production of the lipid second messenger PIP3/PtdIns(3,4,5)P3 (phosphatidylinositol (3,4,5)-trisphosphate) is potentially involved in metabolic regulation, activation of hypertrophy, and survival pathways. Recent studies, highlighted in this review, started to interconnect PI3K pathway activation to Ca²⁺ signaling. This interdependency, by balancing contractility with metabolic control, is crucial for cells of the cardiovascular system and is emerging to play key roles in disease development. Better understanding of the interplay between Ca²⁺ and PI3K signaling is, thus, expected to provide new ground for therapeutic intervention. This review explores the emerging molecular mechanisms linking Ca²⁺ and PI3K signaling in health and disease.

Dysregulation of Calpain Proteolytic Systems Underlies Degenerative Vascular Disorders

Chronic vascular diseases such as atherosclerosis, aneurysms, diabetic angiopathy/retinopathy as well as fibrotic and proliferative vascular diseases are generally complicated by the progression of degenerative insults, which are characterized by endothelial dysfunction, apoptotic/necrotic cell death in vascular/immune cells, remodeling of extracellular matrix or breakdown of elastic lamella. Increasing evidence suggests that dysfunctional calpain proteolytic systems and defective calpain protein metabolism in blood vessels contribute to degenerative disorders. In vascular endothelial cells, the overactivation of conventional calpains consisting of calpain-1 and -2 isozymes can lead to the disorganization of cell-cell junctions, dysfunction of nitric oxide synthase, sensitization of Janus kinase/signal transducer and activator of transcription cascades and depletion of prostaglandin I₂, which contributes to degenerative disorders. In addition to endothelial cell dysfunctions, calpain overactivation results in inflammatory insults in macrophages and excessive fibrogenic/proliferative signaling in vascular smooth muscle cells. Moreover, calpain-6, a non-proteolytic unconventional calpain, is involved in the conversion of macrophages to a pro-atherogenic phenotype, leading to the pinocytotic deposition of low-density lipoprotein cholesterol in the cells. Here, we discuss the recent progress that has been made in our understanding of how calpain contributes to degenerative vascular disorders.