Signals transduced by Ca(2+)/calcineurin and NFATc3/c4 pattern the developing vasculature

Genome-wide profiling of angiogenic cis-regulatory elements unravels cis-regulatory SNPs for vascular abnormality

Angiogenesis is extensively involved in embryonic development and requires complex regulation networks, whose defects can cause a variety of vascular abnormalities. Cis-regulatory elements control gene expression at all developmental stages, but they have not been studied or profiled in angiogenesis yet. In this study, we exploited public DNase-seq and RNA-seq datasets from a VEGFA-stimulated in vitro angiogenic model, and carried out an integrated analysis of the transcriptome and chromatin accessibility across the entire process. Totally, we generated a bank of 47,125 angiogenic cis-regulatory elements with promoter (marker by H3K4me3) and/or enhancer (marker by H3K27ac) activities. Motif enrichment analysis revealed that these angiogenic cis-regulatory elements interacted preferentially with ETS family TFs. With this tool, we performed an association study using our WES data of TAPVC and identified rs199530718 as a cis-regulatory SNP associated with disease risk. Altogether, this study generated a genome-wide bank of angiogenic cis-regulatory elements and illustrated its utility in identifying novel cis-regulatory SNPs for TAPVC, expanding new horizons of angiogenesis as well as vascular abnormality genetics.

SRRM2 splicing factor modulates cell fate in early development

Embryo development is an orchestrated process that relies on tight regulation of gene expression to guide cell differentiation and fate decisions. The Srrm2 splicing factor has recently been implicated in developmental disorders and diseases, but its role in early mammalian development remains unexplored. Here, we show that Srrm2 dosage is critical for maintaining embryonic stem cell pluripotency and cell identity. Srrm2 heterozygosity promotes loss of stemness, characterised by the coexistence of cells expressing naive and formative pluripotency markers, together with extensive changes in gene expression, including genes regulated by serum-response transcription factor (SRF) and differentiation-related genes. Depletion of Srrm2 by RNA interference in embryonic stem cells shows that the earliest effects of Srrm2 heterozygosity are specific alternative splicing events on a small number of genes, followed by expression changes in metabolism and differentiation-related genes. Our findings unveil molecular and cellular roles of Srrm2 in stemness and lineage commitment, shedding light on the roles of splicing regulators in early embryogenesis, developmental diseases and tumorigenesis.

The mechanism of the NFAT transcription factor family involved in oxidative stress response

As a transcriptional activator widely expressed in various tissues, nuclear factor of activated T cells (NFAT) is involved in the regulation of the immune system, the development of the heart and brain systems, and classically mediating pathological processes such as cardiac hypertrophy. Oxidative stress is an imbalance of intracellular redox status, characterized by excessive generation of reactive oxygen species, accompanied by mitochondrial dysfunction, calcium overload, and subsequent lipid peroxidation, inflammation, and apoptosis. Oxidative stress occurs during various pathological processes, such as chronic hypoxia, vascular smooth muscle cell phenotype switching, ischemia-reperfusion, and cardiac remodeling. Calcium overload leads to an increase in intracellular calcium concentration, while NFAT can be activated through calcium-calcineurin, which is also the main regulatory mode of NFAT factors. This review focuses on the effects of NFAT transcription factors on reactive oxygen species production, calcium overload, mitochondrial dysfunction, redox reactions, lipid peroxidation, inflammation, and apoptosis in response to oxidative stress. We hope to provide a reference for the functions and characteristics of NFAT involved in various stages of oxidative stress as well as related potential targets.

Targeting CaN/NFAT in Alzheimer's brain degeneration

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive loss of cognitive functions. While the exact causes of this debilitating disorder remain elusive, numerous investigations have characterized its two core pathologies: the presence of β-amyloid plaques and tau tangles. Additionally, multiple studies of postmortem brain tissue, as well as results from AD preclinical models, have consistently demonstrated the presence of a sustained inflammatory response. As the persistent immune response is associated with neurodegeneration, it became clear that it may also exacerbate other AD pathologies, providing a link between the initial deposition of β-amyloid plaques and the later development of neurofibrillary tangles. Initially discovered in T cells, the nuclear factor of activated T-cells (NFAT) is one of the main transcription factors driving the expression of inflammatory genes and thus regulating immune responses. NFAT-dependent production of inflammatory mediators is controlled by Ca2+-dependent protein phosphatase calcineurin (CaN), which dephosphorylates NFAT and promotes its transcriptional activity. A substantial body of evidence has demonstrated that aberrant CaN/NFAT signaling is linked to several pathologies observed in AD, including neuronal apoptosis, synaptic deficits, and glia activation. In view of this, the role of NFAT isoforms in AD has been linked to disease progression at different stages, some of which are paralleled to diminished cognitive status. The use of classical inhibitors of CaN/NFAT signaling, such as tacrolimus or cyclosporine, or adeno-associated viruses to specifically inhibit astrocytic NFAT activation, has alleviated some symptoms of AD by diminishing β-amyloid neurotoxicity and neuroinflammation. In this article, we discuss the recent findings related to the contribution of CaN/NFAT signaling to the progression of AD and highlight the possible benefits of targeting this pathway in AD treatment.

Bacterial microbiome and host inflammatory gene expression in foreskin tissue

The penile epithelial microbiome remains underexplored. We sequenced human RNA and a segment of the bacterial 16S rRNA gene from the foreskin tissue of 144 adolescents from South Africa and Uganda collected during penile circumcision after receipt of 1-2 doses of placebo, emtricitabine + tenofovir disoproxil fumarate, or emtricitabine + tenofovir alafenamide to investigate the microbiome of foreskin tissue and its potential changes with antiretroviral use. We identified a large number of anaerobic species, including Corynebacterium acnes, which was detected more frequently in participants from South Africa than Uganda. Bacterial populations did not differ by treatment received, and no differentially abundant taxa were identified between placebo versus active drug recipients. The relative abundance of specific bacterial taxa was negatively correlated with expression of genes downstream of the innate immune response to bacteria and regulation of inflammation. Our results show no difference in the tissue microbiome of the foreskin with short-course antiretroviral use but that bacterial taxa were largely inversely correlated with inflammatory gene expression, consistent with commensal colonization.

Calcineurin Is a Universal Regulator of Vessel Function-Focus on Vascular Smooth Muscle Cells

Calcineurin, a serine/threonine phosphatase regulating transcription factors like NFaT and CREB, is well known for its immune modulatory effects and role in cardiac hypertrophy. Results from experiments with calcineurin knockout animals and calcineurin inhibitors indicate that calcineurin also plays a crucial role in vascular function, especially in vascular smooth muscle cells (VSMCs). In the aorta, calcineurin stimulates the proliferation and migration of VSMCs in response to vascular injury or angiotensin II administration, leading to pathological vessel wall thickening. In the heart, calcineurin mediates coronary artery formation and VSMC differentiation, which are crucial for proper heart development. In pulmonary VSMCs, calcineurin/NFaT signaling regulates the release of Ca2+, resulting in increased vascular tone followed by pulmonary arterial hypertension. In renal VSMCs, calcineurin regulates extracellular matrix secretion promoting fibrosis development. In the mesenteric and cerebral arteries, calcineurin mediates a phenotypic switch of VSMCs leading to altered cell function. Gaining deeper insights into the underlying mechanisms of calcineurin signaling will help researchers to understand developmental and pathogenetical aspects of the vasculature. In this review, we provide an overview of the physiological function and pathophysiology of calcineurin in the vascular system with a focus on vascular smooth muscle cells in different organs. Overall, there are indications that under certain pathological settings reduced calcineurin activity seems to be beneficial for cardiovascular health.

Calcineurin regulates aldosterone production via dephosphorylation of NFATC4

The mineralocorticoid aldosterone, secreted by the adrenal zona glomerulosa (ZG), is critical for life, maintaining ion homeostasis and blood pressure. Therapeutic inhibition of protein phosphatase 3 (calcineurin, Cn) results in inappropriately low plasma aldosterone levels despite concomitant hyperkalemia and hyperreninemia. We tested the hypothesis that Cn participates in the signal transduction pathway regulating aldosterone synthesis. Inhibition of Cn with tacrolimus abolished the potassium-stimulated (K+-stimulated) expression of aldosterone synthase, encoded by CYP11B2, in the NCI-H295R human adrenocortical cell line as well as ex vivo in mouse and human adrenal tissue. ZG-specific deletion of the regulatory Cn subunit CnB1 diminished Cyp11b2 expression in vivo and disrupted K+-mediated aldosterone synthesis. Phosphoproteomics analysis identified nuclear factor of activated T cells, cytoplasmic 4 (NFATC4), as a target for Cn-mediated dephosphorylation. Deletion of NFATC4 impaired K+-dependent stimulation of CYP11B2 expression and aldosterone production while expression of a constitutively active form of NFATC4 increased expression of CYP11B2 in NCI-H295R cells. Chromatin immunoprecipitation revealed NFATC4 directly regulated CYP11B2 expression. Thus, Cn controls aldosterone production via the Cn/NFATC4 pathway. Inhibition of Cn/NFATC4 signaling may explain low plasma aldosterone levels and hyperkalemia in patients treated with tacrolimus, and the Cn/NFATC4 pathway may provide novel molecular targets to treat primary aldosteronism.

Fibin regulates cardiomyocyte hypertrophy and causes protein-aggregate-associated cardiomyopathy in vivo

Despite the identification of numerous molecular pathways modulating cardiac hypertrophy its pathogenesis is not completely understood. In this study we define an unexpected role for Fibin ("fin bud initiation factor homolog") in cardiomyocyte hypertrophy. Via gene expression profiling in hypertrophic murine hearts after transverse aortic constriction we found a significant induction of Fibin. Moreover, Fibin was upregulated in another mouse model of cardiac hypertrophy (calcineurin-transgenics) as well as in patients with dilated cardiomyopathy. Immunoflourescence microscopy revealed subcellular localization of Fibin at the sarcomeric z-disc. Overexpression of Fibin in neonatal rat ventricular cardiomyocytes revealed a strong anti-hypertrophic effect through inhibiting both, NFAT- and SRF-dependent signalling. In contrast, transgenic mice with cardiac-restricted overexpression of Fibin developed dilated cardiomyopathy, accompanied by induction of hypertrophy-associated genes. Moreover, Fibin overexpression accelerated the progression to heart failure in the presence of prohypertrophic stimuli such as pressure overload and calcineurin overexpression. Histological and ultrastructural analyses surprisingly showed large protein aggregates containing Fibin. On the molecular level, aggregate formation was accompanied by an induction of the unfolded protein response subsequent UPR-mediated apoptosis and autophagy. Taken together, we identified Fibin as a novel potent negative regulator of cardiomyocyte hypertrophy in vitro. Yet, heart-specific Fibin overexpression in vivo causes development of a protein-aggregate-associated cardiomyopathy. Because of close similarities to myofibrillar myopathies, Fibin represents a candidate gene for cardiomyopathy and Fibin transgenic mice may provide additional mechanistic insight into aggregate formation in these diseases.

The tissue-specific transcriptional landscape underlines the involvement of endothelial cells in health and disease

Endothelial cells (ECs) that line vascular and lymphatic vessels are being increasingly recognized as important to organ function in health and disease. ECs participate not only in the trafficking of gases, metabolites, and cells between the bloodstream and tissues but also in the angiocrine-based induction of heterogeneous parenchymal cells, which are unique to their specific tissue functions. The molecular mechanisms regulating EC heterogeneity between and within different tissues are modeled during embryogenesis and become fully established in adults. Any changes in adult tissue homeostasis induced by aging, stress conditions, and various noxae may reshape EC heterogeneity and induce specific transcriptional features that condition a functional phenotype. Heterogeneity is sustained via specific genetic programs organized through the combinatory effects of a discrete number of transcription factors (TFs) that, at the single tissue-level, constitute dynamic networks that are post-transcriptionally and epigenetically regulated. This review is focused on outlining the TF-based networks involved in EC specialization and physiological and pathological stressors thought to modify their architecture.

A novel implant surface modification mode of Fe3O4-containing TiO2 nanorods with sinusoidal electromagnetic field for osteoblastogenesis and angiogenesis

Implants made of Ti and its alloys are widely utilized in orthopaedic surgeries. However, insufficient osseointegration of the implants often causes complications such as aseptic loosening. Our previous research discovered that disordered titanium dioxide nanorods (TNrs) had satisfactory antibacterial properties and biocompatibility, but TNrs harmed angiogenic differentiation, which might retarded the osseointegration process of the implants. Magnetic nanomaterials have a certain potential in promoting osseointegration, electromagnetic fields within a specific frequency and intensity range can facilitate angiogenic and osteogenic differentiation. Therefore, this study used Fe₃O₄ to endow magnetism to TNrs and explored the regulation effects of Ti, TNrs, and Fe₃O₄-TNrs under 1 ​mT 15 ​Hz sinusoidal electromagnetic field (SEMF) on osteoblastogenesis, osseointegration, angiogenesis, and its mechanism. We discovered that after the addition of SEMF treatment to VR-EPCs cultured on Fe₃O₄-TNrs, the calcineurin/NFAT signaling pathway was activated, which then reversed the inhibitory effect of Fe₃O₄-TNrs on angiogenesis. Besides, Fe₃O₄-TNrs with SEMF enhanced osteogenic differentiation and osseointegration. Therefore, the implant modification mode of Fe₃O₄-TNrs with the addition of SEMF could more comprehensively promote osseointegration and provided a new idea for the modification of implants.

Genetics and Molecular Basis of Congenital Heart Defects in Down Syndrome: Role of Extracellular Matrix Regulation

Down syndrome (DS), a complex disorder that is caused by the trisomy of chromosome 21 (Hsa21), is a major cause of congenital heart defects (CHD). Interestingly, only about 50% of individuals with Hsa21 trisomy manifest CHD. Here we review the genetic basis of CHD in DS, focusing on genes that regulate extracellular matrix (ECM) organization. The overexpression of Hsa21 genes likely underlies the molecular mechanisms that contribute to CHD, even though the genes responsible for CHD could only be located in a critical region of Hsa21. A role in causing CHD has been attributed not only to protein-coding Hsa21 genes, but also to genes on other chromosomes, as well as miRNAs and lncRNAs. It is likely that the contribution of more than one gene is required, and that the overexpression of Hsa21 genes acts in combination with other genetic events, such as specific mutations or polymorphisms, amplifying their effect. Moreover, a key function in determining alterations in cardiac morphogenesis might be played by ECM. A large number of genes encoding ECM proteins are overexpressed in trisomic human fetal hearts, and many of them appear to be under the control of a Hsa21 gene, the RUNX1 transcription factor.

Updating Insights into the Regulatory Mechanisms of Calcineurin-Activated Transcription Factor Crz1 in Pathogenic Fungi

Ca²⁺, as a second messenger in cells, enables organisms to adapt to different environmental stresses by rapidly sensing and responding to external stimuli. In recent years, the Ca²⁺ mediated calcium signaling pathway has been studied systematically in various mammals and fungi, indicating that the pathway is conserved among organisms. The pathway consists mainly of complex Ca²⁺ channel proteins, calcium pumps, Ca²⁺ transporters and many related proteins. Crz1, a transcription factor downstream of the calcium signaling pathway, participates in regulating cell survival, ion homeostasis, infection structure development, cell wall integrity and virulence. This review briefly summarizes the Ca²⁺ mediated calcium signaling pathway and regulatory roles in plant pathogenic fungi. Based on discussing the structure and localization of transcription factor Crz1, we focus on the regulatory role of Crz1 on growth and development, stress response, pathogenicity of pathogenic fungi and its regulatory mechanisms. Furthermore, we explore the cross-talk between Crz1 and other signaling pathways. Combined with the important role and pathogenic mechanism of Crz1 in fungi, the new strategies in which Crz1 may be used as a target to explore disease control in practice are also discussed.

Calcineurin in development and disease

Calcineurin (CaN) is a unique calcium (Ca²⁺) and calmodulin (CaM)-dependent serine/threonine phosphatase that becomes activated in the presence of increased intracellular Ca²⁺ level. CaN then functions to dephosphorylate target substrates including various transcription factors, receptors, and channels. Once activated, the CaN signaling pathway participates in the development of multiple organs as well as the onset and progression of various diseases via regulation of different cellular processes. Here, we review current literature regarding the structural and functional properties of CaN, highlighting its crucial role in the development and pathogenesis of immune system disorders, neurodegenerative diseases, kidney disease, cardiomyopathy and cancer.

Heme oxygenase-1 gene delivery for altering high mobility group box-1 protein in pancreatic islet

Pancreatic islet transplantation is a promising strategy for the treatment of type I diabetes. High-mobility group box-1 (HMGB1), highly expressed in islet cells, is a potent immune stimulator in immune rejection. Heme oxygenase-1 (HO1) gene therapy can modulate the release of HMGB1 by altering intracellular molecules for successful cell transplantation. After delivery of the heme oxygenase-1 (HO1) gene to islet cells using an adeno-associated viral vector (AAV), it was evaluated the changes in cytoplasmic Ca²⁺ ions and calcineurin activity as well as histone acetyltransferase (HAT) and Poly(ADP) ribose polymerase-1 (PARP-1). Inhibition of HMGB1 release was evaluated through altering these intracellular molecules. Then, after transplantation of HO1-transduced islets, the therapeutic effect of them was evaluated through measuring blood glucose level to diabetic mice and through immunohistochemical analysis. The transduced HO1 gene significantly inhibited HMGB1 release in islets that was under the cell damage by hypoxia exposure. It was confirmed that this result was initially due to the decrease in cytoplasmic Ca²⁺ ion concentration and calcineurin activity. In addition, the delivered HO1 gene simultaneously reduced the activity of HAT and PARP-1, which are involved in the translocation of HMGB1 from the nucleus to the cytoplasm. As a result, when the HO1 gene-transduced islets were transplanted into diabetic mice, the treatment efficiency of diabetes was effectively improved by increasing the survival rate of the islets. Collectively, these results suggest that HO1 gene transfer can be used for successful islet transplantation by altering the activity of intracellular signal molecules and reducing HMGB1 release.

Calcineurin (PPP3CB) regulates angiotensin II-dependent vascular remodelling by potentiating EGFR signalling in mice

AIM

This study investigates the role of calcineurin for angiotensin II (AngII)-induced vascular remodelling with the help of a mouse model lacking the catalytic beta subunit of calcineurin (PPP3CB KO).

METHODS

Wildtype (WT) and PPP3CB KO mice were treated for 4 weeks with AngII followed by assessment of blood pressure, histological evaluation of aortas and mRNA analysis of aortic genes PPP3CB-dependently regulated by AngII. Primary murine vascular smooth muscle cells (VSMCs) were used for qPCR, ELISA and Western Blot experiments as well as wound healing and cell proliferation assays.

RESULTS

Upon AngII treatment, PPP3CB KO mice showed less aortic media thickening, lumen dilation and systolic blood pressure compared to WT mice. Next-generation sequencing data of aortic tissue indicated an increase in extracellular matrix components (EMCs), cell migration and cell proliferation. A PPP3CB-dependent increase in EMC was confirmed by qPCR in aorta and VSMCs. PPP3CB-dependent stimulation of VSMC migration could be verified by wound healing assays but markers of enhanced cell proliferation were only detectable in aortic tissue of WT mice but not in isolated WT or KO VSMCs. We could demonstrate in VSMCs with pharmacological inhibitors that PPP3CB leads to enhanced heparin-binding EGF-like growth factor (HB-EGF) secretion, epidermal growth factor receptor (EGFR) activation and consecutive stimulation of transforming growth factor β(TGFβ) and connective tissue growth factor (CTGF) signalling that enhances collagen expression.

CONCLUSION

AngII-induced vascular remodelling involves PPP3CB, which leads to enhanced EMC production, VSMC migration and sustained increase in systolic blood pressure via HBEGF/EGFR-TGFβ-CTGF signalling.

The role of Ca2+ /Calcineurin/NFAT signalling pathway in osteoblastogenesis

The bone remodelling process is closely related to bone health. Osteoblasts and osteoclasts participate in the bone remodelling process under the regulation of various factors inside and outside. Excessive activation of osteoclasts or lack of function of osteoblasts will cause occurrence and development of multiple bone‐related diseases. Ca²⁺/Calcineurin/NFAT signalling pathway regulates the growth and development of many types of cells, such as cardiomyocyte differentiation, angiogenesis, chondrogenesis, myogenesis, bone development and regeneration, etc. Some evidences indicate that this signalling pathway plays an extremely important role in bone formation and bone pathophysiologic changes. This review discusses the role of Ca²⁺/Calcineurin/NFAT signalling pathway in the process of osteogenic differentiation, as well as the influence of regulating each component in this signalling pathway on the differentiation and function of osteoblasts, whereby the relationship between Ca²⁺/Calcineurin/NFAT signalling pathway and osteoblastogenesis could be deeper understood.

Halofuginone, a promising drug for treatment of pulmonary hypertension

BACKGROUND AND PURPOSE

Halofuginone is a febrifugine derivative originally isolated from Chinese traditional herb Chang Shan that exhibits anti-hypertrophic, anti-fibrotic and anti-proliferative effects. We sought to investigate whether halofuginone induced pulmonary vasodilation and attenuates chronic hypoxia-induced pulmonary hypertension (HPH).

EXPERIMENTAL APPROACH

Patch-clamp experiments were conducted to examine the activity of voltage-dependent Ca²⁺ channels (VDCCs) in pulmonary artery smooth muscle cells (PASMCs). Digital fluorescence microscopy was used to measure intracellular Ca²⁺ concentration in PASMCs. Isolated perfused and ventilated mouse lungs were used to measure pulmonary artery pressure (PAP). Mice exposed to hypoxia (10% O₂ ) for 4 weeks were used as model of HPH for in vivo experiments.

KEY RESULTS

Halofuginone increased voltage-gated K⁺ (K_v ) currents in PASMCs and K⁺ currents through KCNA5 channels in HEK cells transfected with KCNA5 gene. HF (0.03-1 μM) inhibited receptor-operated Ca²⁺ entry in HEK cells transfected with calcium-sensing receptor gene and attenuated store-operated Ca²⁺ entry in PASMCs. Acute (3-5 min) intrapulmonary application of halofuginone significantly and reversibly inhibited alveolar hypoxia-induced pulmonary vasoconstriction dose-dependently (0.1-10 μM). Intraperitoneal administration of halofuginone (0.3 mg·kg^-1 , for 2 weeks) partly reversed established PH in mice.

CONCLUSION AND IMPLICATIONS

Halofuginone is a potent pulmonary vasodilator by activating K_v channels and blocking VDCC and receptor-operated and store-operated Ca²⁺ channels in PASMCs. The therapeutic effect of halofuginone on experimental PH is probably due to combination of its vasodilator effects, via inhibition of excitation-contraction coupling and anti-proliferative effects, via inhibition of the PI3K/Akt/mTOR signalling pathway.

Calcineurin-nuclear factor for activated T cells (NFAT) signaling in pathophysiology of wound healing

Wound healing occurred with serial coordinated processes via coagulation-fibrinolysis, inflammation following to immune-activation, angiogenesis, granulation, and the final re-epithelization. Since the dermis forms critical physical and biological barriers, the repair system should be rapidly and accurately functioned to keep homeostasis in our body. The wound healing is impaired or dysregulated via an inappropriate microenvironment, which is easy to lead to several diseases, including fibrosis in multiple organs and psoriasis. Such a disease led to the dysregulation of several types of cells: immune cells, fibroblasts, mural cells, and endothelial cells. Moreover, recent progress in medical studies uncovers the significant concept. The calcium signaling, typically the following calcineurin-NFAT signaling, essentially regulates not only immune cell activations, but also various healing steps via coagulation, inflammation, and angiogenesis. In this review, we summarize the role of the NFAT activation pathway in wound healing and discuss its overall impact on future therapeutic ways.

Understanding Chronic Venous Disease: A Critical Overview of Its Pathophysiology and Medical Management

Chronic venous disease (CVD) is a multifactorial condition affecting an important percentage of the global population. It ranges from mild clinical signs, such as telangiectasias or reticular veins, to severe manifestations, such as venous ulcerations. However, varicose veins (VVs) are the most common manifestation of CVD. The explicit mechanisms of the disease are not well-understood. It seems that genetics and a plethora of environmental agents play an important role in the development and progression of CVD. The exposure to these factors leads to altered hemodynamics of the venous system, described as ambulatory venous hypertension, therefore promoting microcirculatory changes, inflammatory responses, hypoxia, venous wall remodeling, and epigenetic variations, even with important systemic implications. Thus, a proper clinical management of patients with CVD is essential to prevent potential harms of the disease, which also entails a significant loss of the quality of life in these individuals. Hence, the aim of the present review is to collect the current knowledge of CVD, including its epidemiology, etiology, and risk factors, but emphasizing the pathophysiology and medical care of these patients, including clinical manifestations, diagnosis, and treatments. Furthermore, future directions will also be covered in this work in order to provide potential fields to explore in the context of CVD.

Ginsenosides in vascular remodeling: Cellular and molecular mechanisms of their therapeutic action

Evidence is mounting that abnormal vascular remodeling (VR) is a vital pathological event that precedes many cardiovascular diseases (CVD). This provides us with a new research perspective that VR can be a pivotal target for CVD treatment and prevention. However, the current drugs for treating CVD do not fundamentally reverse VR and repair vascular function. The reason may be that a complicated regulatory network is formed between the various signaling pathways involved in VR. Recently, ginsenoside, the main active substance of ginseng, has become increasingly the focus of many researchers for its multiple targets, multiple pathways, and few side effects. Several data have revealed that ginsenosides can improve VR caused by vasodilation dysfunction, abnormal vascular structure and blood pressure. This review is intended to discuss the therapeutic effects and mechanisms of ginsenosides in some diseases involved in VR. Besides, we herein also give a new and contradictory insight into intracellular and molecular signaling of ginsenosides in all kinds of vascular cells. Most importantly, we also discuss the feasibility of ginsenosides Rb1/Rg1/Rg3 in drug development by combining the pharmacodynamics and pharmacokinetics of ginsenosides, and provide a pharmacological basis for the development of ginsenosides in clinical applications.

Mitochondrial Disruption Is Involved in the Effect of Nuclear Factor of Activated T cells, Cytoplasmic 4 on Aggravating Cardiomyocyte Hypertrophy

ABSTRACT

Nuclear factor of activated T cells, cytoplasmic 4 (NFATc4), a nuclear transcription factor, has been implicated in cardiac hypertrophy through the enhancement of hypertrophic gene expression. However, the role of NFATc4 in mitochondrial modulation is mostly unknown. The current study aimed to investigate the role of NFATc4 in regulating mitochondrial function during phenylephrine (PE)-induced cardiac hypertrophy. Our results showed that overexpression of NFATc4 aggravated the PE-induced decrease in mitochondrial genesis, membrane potential, and mitochondrial gene expression as well as impaired mitochondrial respiration. However, knockdown of NFATc4 relieved PE-induced perturbations in mitochondria and cardiomyocyte hypertrophy. Mechanistically, by activating phosphoinositide-dependent kinase 1 and promoting a combination of AKT and phosphoinositide-dependent kinase 1, phosphorylation and sequential acetylation of PGC-1α were aggravated by NFATc4 and suppressed the activity of PGC-1α. In conclusion, NFATc4-regulated factors were shown to be associated with mitochondrial function and exacerbated PE-induced mitochondrial dysfunction. These findings revealed new roles of NFATc4 in cardiac hypertrophy.

Association between Quantitative MR Markers of Cortical Evolving Organization and Gene Expression during Human Prenatal Brain Development

The relationship between structural changes of the cerebral cortex revealed by Magnetic Resonance Imaging (MRI) and gene expression in the human fetal brain has not been explored. In this study, we aimed to test the hypothesis that relative regional thickness (a measure of cortical evolving organization) of fetal cortical compartments (cortical plate [CP] and subplate [SP]) is associated with expression levels of genes with known cortical phenotype. Mean regional SP/CP thickness ratios across age measured on in utero MRI of 25 healthy fetuses (20-33 gestational weeks [GWs]) were correlated with publicly available regional gene expression levels (23-24 GW fetuses). Larger SP/CP thickness ratios (more pronounced cortical evolving organization) was found in perisylvian regions. Furthermore, we found a significant association between SP/CP thickness ratio and expression levels of the FLNA gene (mutated in periventricular heterotopia, congenital heart disease, and vascular malformations). Further work is needed to identify early MRI biomarkers of gene expression that lead to abnormal cortical development.

Isoform-Selective NFAT Inhibitor: Potential Usefulness and Development

Nuclear factor of activated T cells (NFAT), which is the pharmacological target of immunosuppressants cyclosporine and tacrolimus, has been shown to play an important role not only in T cells (immune system), from which their name is derived, but also in many biological events. Therefore, functional and/or structural abnormalities of NFAT are linked to the pathogenesis of diseases in various organs. The NFAT protein family consists of five isoforms, and each isoform performs diverse functions and has unique expression patterns in the target tissues. This diversity has made it difficult to obtain ideal pharmacological output for immunosuppressants that inhibit the activity of almost all NFAT family members, causing serious and wide-ranging side effects. Moreover, it remains unclear whether isoform-selective NFAT regulation can be achieved by targeting the structural differences among NFAT isoforms and whether this strategy can lead to the development of better drugs than the existing ones. This review summarizes the role of the NFAT family members in biological events, including the development of various diseases, as well as the usefulness of and problems associated with NFAT-targeting therapies, including those dependent on current immunosuppressants. Finally, we propose a novel therapeutic strategy based on the molecular mechanisms that enable selective regulation of specific NFAT isoforms.

Effects of Late Conversion from Twice-Daily to Once-Daily Slow Release Tacrolimus on the Insulin Resistance Indexes in Kidney Transplant Patients

The use of tacrolimus (Tac) may be involved in the development of new-onset diabetes after transplantation (NODAT) in a dose-related manner. This study aimed to evaluate the effects of a standard twice-daily formulation of Tac (TacBID) vs. the once-daily slow-release formulation (TacOD) on the basal insulin resistance indexes (Homa and McAuley), and related metabolic parameters, in a cohort of kidney transplant patients. We retrospectively evaluated 20 stable renal transplant recipients who were switched from TacBID to TacOD. Blood levels of Tac were analyzed at one-month intervals from 6 months before to 8 months after conversion. Moreover, Homa and McAuley indexes, C-peptide, insulin, HbA1c, uric acid, triglycerides, low-density lipoprotein (LDL) and high-density lipoprotein (HDL)-cholesterol serum levels and their associations with Tac levels were evaluated. We observed a significant decrease in Tac exposure (8.5 ± 2 ng/mL, CV 0.23 vs. 6.1 ± 1.9 ng/mL, CV 0.31, TacBID vs. TacOD periods, p < 0.001) and no significant changes in Homa (1.42 ± 0.4 vs. 1.8 ± 0.7, p > 0.05) and McAuley indexes (7.12 ± 1 vs. 7.58 ± 1.4, p > 0.05). Similarly, blood levels of glucose, insulin, HbA1c, lipids, and uric acid were unchanged between the two periods, while C-peptide resulted significantly lower after conversion to TacOD. These data suggest that in kidney transplant recipients, reduced Tac exposure has no significant effects on basal insulin sensitivity indexes and metabolic parameters.

Diabetes and hypertension: Pivotal involvement of purinergic signaling

Diabetes mellitus (DM) and hypertension are highly prevalent worldwide health problems and frequently associated with severe clinical complications, such as diabetic cardiomyopathy, nephropathy, retinopathy, neuropathy, stroke, and cardiac arrhythmia, among others. Despite all existing research results and reasonable speculations, knowledge about the role of purinergic system in individuals with DM and hypertension remains restricted. Purinergic signaling accounts for a complex network of receptors and extracellular enzymes responsible for the recognition and degradation of extracellular nucleotides and adenosine. The main components of this system that will be presented in this review are: P1 and P2 receptors and the enzymatic cascade composed by CD39 (NTPDase; with ATP and ADP as a substrate), CD73 (5′-nucleotidase; with AMP as a substrate), and adenosine deaminase (ADA; with adenosine as a substrate). The purinergic system has recently emerged as a central player in several physiopathological conditions, particularly those linked to inflammatory responses such as diabetes and hypertension. Therefore, the present review focuses on changes in both purinergic P1 and P2 receptor expression as well as the activities of CD39, CD73, and ADA in diabetes and hypertension conditions. It can be postulated that the manipulation of the purinergic axis at different levels can prevent or exacerbate the insurgency and evolution of diabetes and hypertension working as a compensatory mechanism.

Calcineurin A gamma and NFATc3/SRPX2 axis contribute to human embryonic stem cell differentiation

Our understanding of signaling pathways regulating the cell fate of human embryonic stem cells (hESCs) is limited. Calcineurin-NFAT signaling is associated with a wide range of biological processes and diseases. However, its role in controlling hESC fate remains unclear. Here, we report that calcineurin A gamma and the NFATc3/SRPX2 axis control the expression of lineage and epithelial-mesenchymal transition (EMT) markers in hESCs. Knockdown of PPP3CC, the gene encoding calcineurin A gamma, or NFATC3, downregulates certain markers both at the self-renewal state and during differentiation of hESCs. Furthermore, NFATc3 interacts with c-JUN and regulates the expression of SRPX2, the gene encoding a secreted glycoprotein known as a ligand of uPAR. We show that SRPX2 is a downstream target of NFATc3. Both SRPX2 and uPAR participate in controlling expression of lineage and EMT markers. Importantly, SRPX2 knockdown diminishes the upregulation of multiple lineage and EMT markers induced by co-overexpression of NFATc3 and c-JUN in hESCs. Together, this study uncovers a previously unknown role of calcineurin A gamma and the NFATc3/SRPX2 axis in modulating the fate determination of hESCs.

Hematopoietic Stem Cell Transcription Factors in Cardiovascular Pathology

Transcription factors as multifaceted modulators of gene expression that play a central role in cell proliferation, differentiation, lineage commitment, and disease progression. They interact among themselves and create complex spatiotemporal gene regulatory networks that modulate hematopoiesis, cardiogenesis, and conditional differentiation of hematopoietic stem cells into cells of cardiovascular lineage. Additionally, bone marrow-derived stem cells potentially contribute to the cardiovascular cell population and have shown potential as a therapeutic approach to treat cardiovascular diseases. However, the underlying regulatory mechanisms are currently debatable. This review focuses on some key transcription factors and associated epigenetic modifications that modulate the maintenance and differentiation of hematopoietic stem cells and cardiac progenitor cells. In addition to this, we aim to summarize different potential clinical therapeutic approaches in cardiac regeneration therapy and recent discoveries in stem cell-based transplantation.

The Protective Effects of Calcineurin on Pancreatitis in Mice Depend on the Cellular Source

BACKGROUND & AIMS

Calcineurin is a ubiquitously expressed central Ca2+-responsive signaling molecule that mediates acute pancreatitis, but little is known about its effects. We compared the effects of calcineurin expression by hematopoietic cells vs pancreas in mouse models of pancreatitis and pancreatitis-associated lung inflammation.

METHODS

We performed studies with mice with hematopoietic-specific or pancreas-specific deletion of protein phosphatase 3, regulatory subunit B, alpha isoform (PPP3R1, also called CNB1), in mice with deletion of CNB1 (Cnb1UBC△/△) and in the corresponding controls for each deletion of CNB1. Acute pancreatitis was induced in mice by administration of caerulein or high-pressure infusion of radiocontrast into biliopancreatic ducts; some mice were also given intraductal infusions of an adeno-associated virus vector that expressed nuclear factor of activated T -cells (NFAT)-luciferase into pancreas. Pancreas, bone marrow, liver, kidney, heart, and lung were collected and analyzed by histopathology, immunohistochemistry, and immunoblots; levels of cytokines were measured in serum. Mouse and human primary pancreatic acinar cells were transfected with a vector that expressed NFAT-luciferase and incubated with an agent that blocks interaction of NFAT with calcineurin; cells were analyzed by immunofluorescence. Calcineurin-mediated neutrophil chemotaxis and reactive oxygen species production were measured in neutrophils from mice.

RESULTS

Mice with hematopoietic-specific deletion of CNB1 developed the same level of local pancreatic inflammation as control mice after administration of caerulein or infusion of radiocontrast into biliopancreatic ducts. Cnb1UBC△/△ mice or mice with pancreas-specific deletion of CNB1 developed less severe pancreatitis and reduced pancreatic inflammation after administration of caerulein or infusion of radiocontrast into biliopancreatic ducts compared with control mice. NFAT was activated in pancreas of Swiss Webster mice given caerulein or infusions of radiocontrast into biliopancreatic ducts. Blocking the interaction between calcineurin and NFAT did not reduce pancreatic acinar cell necrosis in response to caerulein or infusions of radiocontrast. Mice with hematopoietic-specific deletion of CNB1 (but not mice with pancreas-specific deletion of CNB1) had reduced infiltration of lung tissues by neutrophils. Neutrophil chemotaxis and production of reactive oxygen species were decreased after incubation with a calcineurin inhibitor.

CONCLUSIONS

Hematopoietic and neutrophil expression of calcineurin promotes pancreatitis-associated lung inflammation, whereas pancreatic calcineurin promotes local pancreatic inflammation. The findings indicate that the protective effects of blocking or deleting calcineurin on pancreatitis are mediated by the source of its expression. This information should be used in the development of strategies to inhibit calcineurin for the prevention of pancreatitis and pancreatitis-associated lung inflammation.

The constitutive activity of the viral-encoded G protein-coupled receptor US28 supports a complex signalling network contributing to cancer development

US28 is a viral G protein-coupled receptor (GPCR) encoded by the human cytomegalovirus (HCMV). This receptor, expressed both during lytic replication and viral latency, is required for latency. US28 is binding to a wide variety of chemokines but also exhibits a particularly high constitutive activity robustly modulating a wide network of cellular pathways altering the host cell environment to benefit HCMV infection. Several studies suggest that US28-mediated signalling may contribute to cancer progression. In this review, we discuss the unique structural characteristics that US28 acquired through evolution that confer a robust constitutive activity to this viral receptor. We also describe the wide downstream signalling network activated by this constitutive activation of US28 and discuss how these signalling pathways may promote and support important cellular aspects of cancer.

NULP1 Alleviates Cardiac Hypertrophy by Suppressing NFAT3 Transcriptional Activity

Background The development of pathological cardiac hypertrophy involves the coordination of a series of transcription activators and repressors, while their interplay to trigger pathological gene reprogramming remains unclear. NULP1 (nuclear localized protein 1) is a member of the basic helix-loop-helix family of transcription factors and its biological functions in pathological cardiac hypertrophy are barely understood. Methods and Results Immunoblot and immunostaining analyses showed that NULP1 expression was consistently reduced in the failing hearts of patients and hypertrophic mouse hearts and rat cardiomyocytes. Nulp1 knockout exacerbates aortic banding-induced cardiac hypertrophy pathology, which was significantly blunted by transgenic overexpression of Nulp1. Signal pathway screening revealed the nuclear factor of activated T cells (NFAT) pathway to be dramatically suppressed by NULP1. Coimmunoprecipitation showed that NULP1 directly interacted with the topologically associating domain of NFAT3 via its C-terminal region, which was sufficient to suppress NFAT3 transcriptional activity. Inactivation of the NFAT pathway by VIVIT peptides in vivo rescued the aggravated pathogenesis of cardiac hypertrophy resulting from Nulp1 deficiency. Conclusions NULP1 is an endogenous suppressor of NFAT3 signaling under hypertrophic stress and thus negatively regulates the pathogenesis of cardiac hypertrophy. Targeting overactivated NFAT by NULP1 may be a novel therapeutic strategy for the treatment of pathological cardiac hypertrophy and heart failure.

TMEM100 is a key factor for specification of lymphatic endothelial progenitors

BACKGROUND

TMEM100 is identified as a downstream gene of bone morphogenetic protein 9 (BMP9) signaling via activin receptor-like kinase 1 (ALK1), which is known to participate in lymphangiogenesis as well as angiogenesis. TMEM100 has been shown to be important for blood vessel formation and maintenance, but its role in the development of lymphatic vasculature remains unknown. The objective is to investigate the role of TMEM100 in development of the lymphatic system.

METHODS AND RESULTS

Global Tmem100 gene deletion was induced by tamoxifen on 10.5 days post-coitus. Tmem100-inducible knockout (iKO) embryos in embryonic days (E)14.5-16.5 exhibited edema and blood-filled enlarged lymphatics with misconnections between veins and lymphatic vessels. For a reciprocal approach, we have generated a novel mouse line in which TMEM100 overexpression (OE) can be induced in endothelial cells by intercrossing with Tie2-Cre driver. TMEM100-OE embryos at E12.5-14.5 exhibited edema with small size and number of lymphatic vessels, the exact opposite phenotypes of Tmem100-iKOs. In Tmem100-iKO embryos, the number of progenitors of lymphatic endothelial cells (LECs) in the cardinal vein was increased, while it was decreased in TMEM100-OE embryos. The activity of NOTCH signaling, which limits the number of progenitors of LECs in the cardinal vein, was decreased in Tmem100-iKO embryos, whereas it was increased in TMEM100-OE embryos.

CONCLUSION

TMEM100 plays an important role in the specification of LECs in the cardinal veins, at least in part, by regulating the NOTCH signaling.

Purinergic Signaling During Hyperglycemia in Vascular Smooth Muscle Cells

The activation of purinergic receptors by nucleotides and/or nucleosides plays an important role in the control of vascular function, including modulation of vascular smooth muscle excitability, and vascular reactivity. Accordingly, purinergic receptor actions, acting as either ion channels (P2X) or G protein-coupled receptors (GCPRs) (P1, P2Y), target diverse downstream effectors, and substrates to regulate vascular smooth muscle function and vascular reactivity. Both vasorelaxant and vasoconstrictive effects have been shown to be mediated by different purinergic receptors in a vascular bed- and species-specific manner. Purinergic signaling has been shown to play a key role in altering vascular smooth muscle excitability and vascular reactivity following acute and short-term elevations in extracellular glucose (e.g., hyperglycemia). Moreover, there is evidence that vascular smooth muscle excitability and vascular reactivity is severely impaired during diabetes and that this is mediated, at least in part, by activation of purinergic receptors. Thus, purinergic receptors present themselves as important candidates mediating vascular reactivity in hyperglycemia, with potentially important clinical and therapeutic potential. In this review, we provide a narrative summarizing our current understanding of the expression, function, and signaling of purinergic receptors specifically in vascular smooth muscle cells and discuss their role in vascular complications following hyperglycemia and diabetes.

Clinical and Genetic Determinants of Varicose Veins

BACKGROUND

Varicose veins are a common problem with no approved medical therapies. Although it is believed that varicose vein pathogenesis is multifactorial, there is limited understanding of the genetic and environmental factors that contribute to their formation. Large-scale studies of risk factors for varicose veins may highlight important aspects of pathophysiology and identify groups at increased risk for disease.

METHODS

We applied machine learning to agnostically search for risk factors of varicose veins in 493 519 individuals in the UK Biobank. Predictors were further studied with univariable and multivariable Cox regression analyses (2441 incident events). A genome-wide association study of varicose veins was also performed among 337 536 unrelated individuals (9577 cases) of white British descent, followed by expression quantitative loci and pathway analyses. Because height emerged as a new candidate risk factor, we performed mendelian randomization analyses to assess a potential causal role for height in varicose vein development.

RESULTS

Machine learning confirmed several known (age, sex, obesity, pregnancy, history of deep vein thrombosis) and identified several new risk factors for varicose vein disease, including height. After adjustment for traditional risk factors in Cox regression, greater height remained independently associated with varicose veins (hazard ratio for upper versus lower quartile, 1.74; 95% CI, 1.51-2.01; P<0.0001). A genome-wide association study identified 30 new genome-wide significant loci, identifying pathways involved in vascular development and skeletal/limb biology. Mendelian randomization analysis provided evidence that increased height is causally related to varicose veins (inverse-variance weighted: odds ratio, 1.26; P=2.07×10^-16).

CONCLUSIONS

Using data from nearly a half-million individuals, we present a comprehensive genetic and epidemiological study of varicose veins. We identified novel clinical and genetic risk factors that provide pathophysiological insights and could help future improvements of treatment of varicose vein disease.

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.

Nfatc4 Deficiency Attenuates Ototoxicity by Suppressing Tnf-Mediated Hair Cell Apoptosis in the Mouse Cochlea

The loss of sensory hair cells in the cochlea is the major cause of sensorineural hearing loss, and inflammatory processes and immune factors in response to cochlear damage have been shown to induce hair cell apoptosis. The expression and function of Nfatc4 in the cochlea remains unclear. In this study, we investigated the expression of Nfatc4 in the mouse cochlea and explored its function using Nfatc4^−/− mice. We first showed that Nfatc4 was expressed in the cochlear hair cells. Cochlear hair cell development and hearing function were normal in Nfatc4^−/− mice, suggesting that Nfatc4 is not critical for cochlear development. We then showed that when the hair cells were challenged by ototoxic drugs Nfatc4 was activated and translocated from the cytoplasm to the nucleus, and this was accompanied by increased expression of Tnf and its downstream targets and subsequent hair cell apoptosis. Finally, we demonstrated that Nfatc4-deficient hair cells showed lower sensitivity to damage induced by ototoxic drugs and noise exposure compared to wild type controls. The Tnf-mediated apoptosis pathway was attenuated in Nfatc4-deficient cochlear epithelium, and this might be the reason for the reduced sensitivity of Nfatc4-deficient hair cells to injury. These findings suggest that the amelioration of inflammation-mediated hair cell apoptosis by inhibition of Nfatc4 activation might have significant therapeutic value in preventing ototoxic drug or noise exposure-induced sensorineural hearing loss.

Linc00423 as a tumor suppressor in retroperitoneal liposarcoma via activing MAPK signaling pathway through destabilizing of NFATC3

Unraveling the noncoding RNA expression networks governing cancer initiation and development is essential while remains largely uncompleted in retroperitoneal liposarcoma (RLS). Through RNA-seq technologies and computational biology, deregulated long noncoding RNAs (lncRNAs) are being identified and reveal that lncRNAs are implicated in serial steps of RLS development. High-throughput sequencing with computational methods for assembling the transcriptome of five paired RLS patient’s tissues. We found that long intergenic noncoding RNA 423 (linc00423) was downregulated in RLS tissues. Gain-of-function assays revealed that overexpressed linc00423 obviously inhibited RLS cell growth in vitro and in vivo. Additionally, RNA sequence, RNA-pulldown and RIP assays evidenced that linc00423 involved in MAPK signaling pathway via destabilizing of nuclear factor of activated T-cells 3 (NFATC3). Summing up, our findings demonstrated that linc00423 acted as the tumor suppressor in RLS cells through regulating the protein level of NFATC3 at a post-transcriptional level and negatively regulated the MAPK signaling pathway at a transcriptional level. Linc00423 might serve as a candidate prognostic biomarker and a target for novel therapies of RLS patients.

Calcineurin B1 subunit in human peripheral blood mononuclear cells and its role in idiopathic membranous nephropathy

The immune responses involved in the pathogenesis of idiopathic membranous nephropathy (IMN) have not been fully understood. Calcineurin, a key signaling enzyme in T-cell activation, may be implicated in IMN. The present study aimed to investigate the role of calcineurin B1 subunit (CnB1) in IMN and the potential mechanism.A total of 59 biopsy-proven IMN patients and 28 healthy controls were recruited. The CnB1 expression in human peripheral blood mononuclear cells (PBMCs) was assessed by Western blotting. Knockdown and overexpression of CnB1 in Jurkat T cell line were achieved by small interference RNA (siRNA) transfection and lentiviral transduction, respectively.It was found that PBMCs CnB1 expression was significantly increased in IMN patients (P = .002), but unrelated to the severity and prognosis of IMN. Knockdown of CnB1 in Jurkat cells inhibited the nuclear factor of activated T cells (NFAT)-regulated gene expression required for T-cell activation.Our study suggested the potential role of CnB1 in the occurrence of IMN. The mechanism maybe involved the effect of CnB1 on the T-cell activation mediated by calcineurin-NFAT signaling.

Cardiomyocyte calcineurin is required for the onset and progression of cardiac hypertrophy and fibrosis in adult mice

Previous studies have demonstrated that activation of calcineurin induces pathological cardiac hypertrophy (CH). In these studies, loss-of-function was mostly achieved by systemic administration of the calcineurin inhibitor cyclosporin A. The lack of conditional knockout models for calcineurin function has impeded progress toward defining the role of this protein during the onset and the development of CH in adults. Here, we exploited a mouse model of CH based on the infusion of a hypertensive dose of angiotensin II (AngII) to model the role of calcineurin in CH in adulthood. AngII-induced CH in adult mice was reduced by treatment with cyclosporin A, without affecting the associated increase in blood pressure, and also by induction of calcineurin deletion in adult mouse cardiomyocytes, indicating that cardiomyocyte calcineurin is required for AngII-induced CH. Surprisingly, cardiac-specific deletion of calcineurin, but not treatment of mice with cyclosporin A, significantly reduced AngII-induced cardiac fibrosis and apoptosis. Analysis of profibrotic genes revealed that AngII-induced expression of Tgfβ family members and Lox was not inhibited by cyclosporin A but was markedly reduced by cardiac-specific calcineurin deletion. These results show that AngII induces a direct, calcineurin-dependent prohypertrophic effect in cardiomyocytes, as well as a systemic hypertensive effect that is independent of calcineurin activity.

The calcineurin regulatory subunit polymorphism and the treatment efficacy of tacrolimus for idiopathic membranous nephropathy

Tacrolimus is considered to be one of the main therapeutic options for idiopathic membranous nephropathy (IMN). This study aimed to investigate the association of variants in genes encoding the binding protein and the drug target (calcineurin) of tacrolimus with the efficacy in IMN patients and the potential mechanism. Sixty-seven IMN patients treated with tacrolimus were enrolled retrospectively. Sanger sequencing was performed to search for variants in all exons of the genes in 8 IMN patients and genotype for the detected variants in the other 59 patients. The molecular mechanism underlying the relationship between the variants and the efficacy was explored in human peripheral blood mononuclear cells (PBMCs) and other cell lines. Single nucleotide polymorphism rs875 (T > C) in the 3'untranslated region (3'UTR) of PPP3R1 encoding calcineurin regulatory subunit was found to be associated with the treatment efficacy of tacrolimus for IMN. Patients carrying TT genotype had a significantly higher remission rate than those carrying TC/CC genotype (83% vs. 47%, P = 0.008). Western blot showed that the TT genotype carriers exhibited reduced PPP3R1 protein levels in PBMCs (P = 0.02). Compared with C allele, T allele displayed increased binding affinity for miR-582-5p in the luciferase reporter assay (P < 0.001). Moreover, knockdown of PPP3R1 in Jurkat T cell line enhanced the immunosuppressive effect of tacrolimus. Our study revealed the association of PPP3R1 3'UTR polymorphism rs875 with the efficacy of tacrolimus in IMN patients. The functional polymorphism might alter PPP3R1 expression via modulating the interaction of miR-582-5p with PPP3R1, which further affected the immunosuppressive effect of tacrolimus.

Regulation of nuclear factor of activated T cells (NFAT) and downstream myogenic proteins during dehydration in the African clawed frog

Xenopus laevis, otherwise known as the African clawed frog, undergoes natural dehydration of up to 30% of its total body water during the dry season in sub-Saharan Africa. To survive under these conditions, a variety of physiological and biochemical changes take place in X. laevis. We were interested in understanding the role that the calcineurin-NFAT pathway plays during dehydration stress response in the skeletal muscles of X. laevis. Immunoblotting was performed to characterize the protein levels of NFATc1-4, calcium signalling proteins, in addition to myogenic proteins (MyoD, MyoG, myomaker). In addition, DNA-protein interaction ELISAs were used to assess the binding of NFATs to their consensus binding sequence, and to identify the effect of urea on NFAT-binding. Our results showed that NFATc1 and c4 protein levels decreased during dehydration, and there were no changes in NFATc2, c3, and calcium signalling proteins. However, MyoG and myomaker both showed increases in protein levels during dehydration, thus indicating that the late myogenic program involving myoblast differentiation, but not satellite cell activation and myoblast proliferation, could be involved in preserving the skeletal muscle of X. laevis during dehydration. In addition, we observed that urea seems to reduce NFATc3-binding to DNA during control, but not during dehydration, possibly indicating that NFATc3 is protected from the denaturing effects of urea as it accumulates during dehydration. These findings expand upon our knowledge of adaptive responses to dehydration, and they identify specific protein targets that could be used to protect the skeletal muscle from damage during stress.

IP3R-mediated Ca2+ signals govern hematopoietic and cardiac divergence of Flk1+ cells via the calcineurin-NFATc3-Etv2 pathway

Ca2+ signals participate in various cellular processes with spatial and temporal dynamics, among which, inositol 1,4,5-trisphosphate receptors (IP3Rs)-mediated Ca2+ signals are essential for early development. However, the underlying mechanisms of IP3R-regulated cell fate decision remain largely unknown. Here we report that IP3Rs are required for the hematopoietic and cardiac fate divergence of mouse embryonic stem cells (mESCs). Deletion of IP3Rs (IP3R-tKO) reduced Flk1+/PDGFRα- hematopoietic mesoderm, c-Kit+/CD41+ hematopoietic progenitor cell population, and the colony-forming unit activity, but increased cardiac progenitor markers as well as cardiomyocytes. Concomitantly, the expression of a key regulator of hematopoiesis, Etv2, was reduced in IP3R-tKO cells, which could be rescued by the activation of Ca2+ signals and calcineurin or overexpression of constitutively active form of NFATc3. Furthermore, IP3R-tKO impaired specific targeting of Etv2 by NFATc3 via its evolutionarily conserved cis-element in differentiating ESCs. Importantly, the activation of Ca2+-calcineurin-NFAT pathway reversed the phenotype of IP3R-tKO cells. These findings reveal an unrecognized governing role of IP3Rs in hematopoietic and cardiac fate commitment via IP3Rs-Ca2+-calcineurin-NFATc3-Etv2 pathway.

Unique properties of TCR-activated p38 are necessary for NFAT-dependent T-cell activation

Nuclear factor of activated T cells (NFAT) transcription factors are required for induction of T-cell cytokine production and effector function. Although it is known that activation via the T-cell antigen receptor (TCR) results in 2 critical steps, calcineurin-mediated NFAT1 dephosphorylation and NFAT2 up-regulation, the molecular mechanisms underlying each are poorly understood. Here we find that T cell p38, which is activated by an alternative pathway independent of the mitogen-activated protein (MAP) kinase cascade and with different substrate specificities, directly controls these events. First, alternatively (but not classically) activated p38 was required to induce the expression of the AP-1 component c-Fos, which was necessary for NFAT2 expression and cytokine production. Second, alternatively (but not classically) activated p38 phosphorylated NFAT1 on a heretofore unidentified site, S79, and in its absence NFAT1 was unable to interact with calcineurin or migrate to the nucleus. These results demonstrate that the acquisition of unique specificities by TCR-activated p38 orchestrates NFAT-dependent T-cell functions.

The p38 MAP kinase, which is required for a large number of important biological responses, is activated by an enzymatic cascade that results in its dual phosphorylation on p38^T180Y182. T cells have evolved a unique pathway in which T-cell antigen receptor (TCR) ligation results in phosphorylation of p38^Y323 (the alternative pathway). Why T cells acquired this pathway is the subject of conjecture. In this study, we examine the activation of 2 members of the nuclear factor of activated T cells (NFAT) family, which, when dephosphorylated by calcineurin, migrate from the cytoplasm to the nucleus. In T cells with the alternative pathway ablated by a single amino acid substitution (p38^Y323F), NFAT1 remained in the cytoplasm after stimulation via the TCR. Studies identified NFAT1^S79 as a target for alternatively (but not classically) activated p38, and phosphorylation of this residue was required for binding calcineurin and nuclear translocation. Furthermore, although classically activated p38 induced NFAT1 translocation in the absence of NFAT1^S79 phosphorylation, unlike alternatively activated p38 it did not cause NFAT2 up-regulation. This paradox was resolved by the finding that only the latter induces c-Fos, which binds to the NFAT2 promoter and participates in its up-regulation. These T-cell-specific p38 activities provide a strong rationale for the acquisition of the alternative mechanism for activating p38.

Downregulation of NFAT3 Due to Lack of T-Box Transcription Factor TBX5 Is Crucial for Cytokine Expression in T Cells

The NFAT family transcription factors play crucial roles in immunological and other biological activities. NFAT3 is rarely expressed in T cells, and the mechanisms and significance of the specific NFAT3 downregulation in T cells have been unknown. In human CD4⁺ T cells, overexpression of NFAT1 and NFAT3 enhanced and suppressed IL-2 expression, respectively. NFAT3 downregulation in Jurkat cells using RNA interference technology augmented IL-2 expression, whereas a knockdown of NFAT1, NFAT2, and NFAT4 suppressed it. The promoter/enhancer activity of the NFAT-binding site in the IL-2 gene was upregulated and downregulated by NFAT1 and NFAT3, respectively. A study employing NFAT1/NFAT3 chimeric molecules revealed that the region in NFAT3 responsible for NFAT promoter activity inhibition was located within its N-terminal transactivation domain, Ca²⁺-regulatory domain, and DNA-binding domain. Downregulation of NFAT3 expression in T cells is mediated by lower chromatin accessibility and enhancer activity in its promoter in comparison with aortic smooth muscle cells expressing endogenous NFAT3. The binding sites of T-box transcription factor TBX5 and NK-2 transcription factor-related locus 5 Nkx2.5, which were expressed at higher levels in aortic smooth muscle cells than in T cells, were located within the -387 to +97 NFAT3 promoter region, exhibiting the maximum enhancer activity. Mutating the binding site of TBX5 but not Nkx2.5 diminished the NFAT3 promoter activity, whereas the overexpression of TBX5 enhanced it. Introduction of TBX5 into CD4⁺ T cells enhanced the expression of NFAT3 and suppressed that of IL-2. TBX5 deficiency-mediated downregulation of NFAT3 is crucial for the high cytokine-producing activity of T cells.

Wnt signaling in cardiovascular disease: opportunities and challenges

PURPOSE OF REVIEW

Cardiometabolic diseases increasingly afflict our aging, dysmetabolic population. Complex signals regulating low-density lipoprotein receptor-related protein (LRP) and frizzled protein family members - the plasma membrane receptors for the cadre of Wnt polypeptide morphogens - contribute to the control of cardiovascular homeostasis.

RECENT FINDINGS

Both canonical (β-catenin-dependent) and noncanonical (β-catenin-independent) Wnt signaling programs control vascular smooth muscle (VSM) cell phenotypic modulation in cardiometabolic disease. LRP6 limits VSM proliferation, reduces arteriosclerotic transcriptional reprogramming, and preserves insulin sensitivity while LRP5 restrains foam cell formation. Adipose, skeletal muscle, macrophages, and VSM have emerged as important sources of circulating Wnt ligands that are dynamically regulated during the prediabetes-diabetes transition with cardiometabolic consequences. Platelets release Dkk1, a LRP5/LRP6 inhibitor that induces endothelial inflammation and the prosclerotic endothelial-mesenchymal transition. By contrast, inhibitory secreted frizzled-related proteins shape the Wnt signaling milieu to limit myocardial inflammation with ischemia-reperfusion injury. VSM sclerostin, an inhibitor of canonical Wnt signaling in bone, restrains remodeling that predisposes to aneurysm formation, and is downregulated in aneurysmal vessels by epigenetic methylation.

SUMMARY

Components of the Wnt signaling cascade represent novel targets for pharmacological intervention in cardiometabolic disease. Conversely, strategies targeting the Wnt signaling cascade for other therapeutic purposes will have cardiovascular consequences that must be delineated to establish clinically useful pharmacokinetic-pharmacodynamic relationships.

Gα13 ablation reprograms myofibers to oxidative phenotype and enhances whole-body metabolism

Skeletal muscle is a key organ in energy homeostasis owing to its high requirement for nutrients. Heterotrimeric G proteins converge signals from cell-surface receptors to potentiate or blunt responses against environmental changes. Here, we show that muscle-specific ablation of Gα13 in mice promotes reprogramming of myofibers to the oxidative type, with resultant increases in mitochondrial biogenesis and cellular respiration. Mechanistically, Gα13 and its downstream effector RhoA suppressed nuclear factor of activated T cells 1 (NFATc1), a chief regulator of myofiber conversion, by increasing Rho-associated kinase 2-mediated (Rock2-mediated) phosphorylation at Ser243. Ser243 phosphorylation of NFATc1 was reduced after exercise, but was higher in obese animals. Consequently, Gα13 ablation in muscles enhanced whole-body energy metabolism and increased insulin sensitivity, thus affording protection from diet-induced obesity and hepatic steatosis. Our results define Gα13 as a switch regulator of myofiber reprogramming, implying that modulations of Gα13 and its downstream effectors in skeletal muscle are a potential therapeutic approach to treating metabolic diseases.

FK506 suppresses hypoxia‑induced inflammation and protects tight junction function via the CaN‑NFATc1 signaling pathway in retinal microvascular epithelial cells

The present study aimed to identify whether FK506 suppresses hypoxia‑induced inflammation and protects tight junction function via the calcineurin‑nuclear factor of activated T‑cells 1 (CaN‑NFATc1) signaling pathway in mouse retinal microvascular endothelial cells (mRMECs). The mRMECs were treated with FK506 at different concentrations following the induction of hypoxia. Trans‑epithelial electrical resistance (TEER) and cell permeability were examined to measure the integrity of the tight junctions. The concentrations of inflammatory cytokines were measured using reverse transcription‑quantitative polymerase chain reaction analysis and enzyme‑linked immunosorbent assays. The protein expression levels of zonula occludens‑1 (ZO‑1) and nuclear factor of activated T‑cell 1 (NFATc1) were identified using immunofluorescent microscopy and western blot analysis. The TEER value was decreased following hypoxia, but increased following treatment with FK506 (1 and 10 µM) for 24 and 48 h. The protein expression of ZO‑1 was also increased following FK506 treatment for 24 h at 1 and 10 µM. By contrast, following treatment with FK506 (1 and 10 µM) for 24 and 48 h, the elevated cell permeability in the hypoxia group was significantly downregulated. Similarly, the concentrations of inflammatory cytokines, including cyclooxygenase‑2, inducible nitric oxide synthase, monocyte chemoattractant protein‑1, interleukin‑6, intercellular adhesion molecule‑1 and vascular cell adhesion molecule‑1, were downregulated following treatment with FK506 for 24 h at 1 and 10 µM. Following treatment with FK506, the level of total NFATc1 was downregulated and the level of phosphorylated NFATc1 was upregulated. Taken together, FK506 suppressed injury to the tight junctions and downregulated the expression of inflammatory cytokines in hypoxia‑induced mRMECs via the CaN‑NFATc1 signaling pathway. This suggests a potentially effective therapy for hypoxia‑induced retinal microangiopathy.

Soluble Epoxide Hydrolase Inhibition Protected against Angiotensin II-induced Adventitial Remodeling

Epoxyeicosatrienoic acids (EETs), the metabolites of cytochrome P450 epoxygenases derived from arachidonic acid, exert important biological activities in maintaining cardiovascular homeostasis. Soluble epoxide hydrolase (sEH) hydrolyzes EETs to less biologically active dihydroxyeicosatrienoic acids. However, the effects of sEH inhibition on adventitial remodeling remain inconclusive. In this study, the adventitial remodeling model was established by continuous Ang II infusion for 2 weeks in C57BL/6 J mice, before which sEH inhibitor 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU) was administered by gavage. Adventitial remodeling was evaluated by histological analysis, western blot, immunofluorescent staining, calcium imaging, CCK-8 and transwell assay. Results showed that Ang II infusion significantly induced vessel wall thickening, collagen deposition, and overexpression of α-SMA and PCNA in aortic adventitia, respectively. Interestingly, these injuries were attenuated by TPPU administration. Additionally, TPPU pretreatment overtly prevented Ang II-induced primary adventitial fibroblasts activation, characterized by differentiation, proliferation, migration, and collagen synthesis via Ca²⁺-calcineurin/NFATc3 signaling pathway in vitro. In summary, our results suggest that inhibition of sEH could be considered as a novel therapeutic strategy to treat adventitial remodeling related disorders.