Vascular smooth muscle LRP6 limits arteriosclerotic calcification in diabetic LDLR-/- mice by restraining noncanonical Wnt signals

Cdc42 deletion yielded enamel defects by disrupting mitochondria and producing reactive oxygen species in dental epithelium

Developmental defects of enamel are common due to genetic and environmental factors before and after birth. Cdc42, a Rho family small GTPase, regulates prenatal tooth development in mice. However, its role in postnatal tooth development, especially enamel formation, remains elusive. Here, we investigated Cdc42 functions in mouse enamel development and tooth repair after birth. Cdc42 showed highly dynamic temporospatial patterns in the developing incisors, with robust expression in ameloblast and odontoblast layers. Strikingly, epithelium-specific Cdc42 deletion resulted in enamel defects in incisors. Ameloblast differentiation was inhibited, and hypomineralization of enamel was observed upon epithelial Cdc42 deletion. Proteomic analysis showed that abnormal mitochondrial components, phosphotransferase activity, and ion channel regulator activity occurred in the Cdc42 mutant dental epithelium. Reactive oxygen species accumulation was detected in the mutant mice, suggesting that abnormal oxidative stress occurred after Cdc42 depletion. Moreover, Cdc42 mutant mice showed delayed tooth repair and generated less calcified enamel. Mitochondrial dysfunction and abnormal oxygen consumption were evidenced by reduced Apool and Timm8a1 expression, increased Atp5j2 levels, and reactive oxygen species overproduction in the mutant repair epithelium. Epithelium-specific Cdc42 deletion attenuated ERK1/2 signaling in the labial cervical loop. Aberrant Sox2 expression in the mutant labial cervical loop after clipping might lead to delayed tooth repair. These findings suggested that mitochondrial dysfunction, up-regulated oxidative stress, and abnormal ion channel activity may be among multiple factors responsible for the observed enamel defects in Cdc42 mutant incisors. Overall, Cdc42 exerts multidimensional and pivotal roles in enamel development and is particularly required for ameloblast differentiation and enamel matrix formation.

Protein Arginine Methyltransferases: Emerging Targets in Cardiovascular and Metabolic Disease

Cardiovascular diseases (CVDs) and metabolic disorders stand as formidable challenges that significantly impact the clinical outcomes and living quality for afflicted individuals. An intricate comprehension of the underlying mechanisms is paramount for the development of efficacious therapeutic strategies. Protein arginine methyltransferases (PRMTs), a class of enzymes responsible for the precise regulation of protein methylation, have ascended to pivotal roles and emerged as crucial regulators within the intrinsic pathophysiology of these diseases. Herein, we review recent advancements in research elucidating on the multifaceted involvements of PRMTs in cardiovascular system and metabolic diseases, contributing significantly to deepen our understanding of the pathogenesis and progression of these maladies. In addition, this review provides a comprehensive analysis to unveil the distinctive roles of PRMTs across diverse cell types implicated in cardiovascular and metabolic disorders, which holds great potential to reveal novel therapeutic interventions targeting PRMTs, thus presenting promising perspectives to effectively address the substantial global burden imposed by CVDs and metabolic disorders.

Inhibition of vascular calcification by Compound Danshen Dripping Pill through multiple mechanisms

BACKGROUND

Vascular calcification refers to the abnormal accumulation of calcium in the walls of blood vessels and is a risk factor often overlooked in cardiovascular disease. However, there is currently no specific drug for treating vascular calcification. Compound Danshen Dripping Pill (CDDP) is widely used to treat cardiovascular diseases, but its effect on vascular calcification has not been reported.

PURPOSE

We investigated the effects of CDDP on vascular calcification in ApoE-/- mice and in vitro and elucidated its mechanism of action.

STUDY DESIGN

Firstly, we found that CDDP has the potential to improve calcification based on network pharmacology analysis. Then, we performed the following experiments: in vivo, ApoE-/- mice were fed a high-fat diet randomly supplemented with CDDP for 16 weeks. Atherosclerosis and vascular calcification were determined. In vitro, human aortic smooth muscle cells (HASMCs), human umbilical vein endothelial cells (HUVECs), and human aortic endothelial cells (HAECs) were used to determine the mechanisms for CDDP-inhibited vascular calcification.

RESULTS

In this study, we observed that CDDP reduced intimal calcification in atherosclerotic lesions of ApoE-deficient mice fed a high-fat diet, as well as the calcification in cultured SMCs and ECs. Mechanistically, CDDP inhibited the Wnt/β-catenin pathway by up-regulating the expression of DKK1 and LRP6, which are upstream inhibitors of Wnt, leading to a reduction in the expression of osteoblastic transition markers (ALP, OPN, BMP2, and RUNX2). Furthermore, CDDP enhanced the secretion of DKK1, which plays a role in mediating EC-SMC crosstalk in calcification. Additionally, VC contributes to vascular aging by inhibiting Sirt1 and increasing senescence parameters (SA-β-gal, p21, and p16). However, CDDP reversed these changes by activating Sirt1. CDDP also reduced the levels of pro-inflammatory cytokines and the senescence-associated secretory phenotype in vivo and in vitro.

CONCLUSIONS

Our study suggests that CDDP reduces vascular calcification by regulating the DKK1/LRP6/β-catenin signaling pathway in ECs/SMCs and interactions with the crosstalk of ECs and SMCs. It also reduces the senescence of ECs/SMCs, contributing to the Sirt1 activation, indicating CDDP's novel role in ameliorating vascular calcification.

FOXO1 regulates RUNX2 ubiquitination through SMURF2 in calcific aortic valve disease

The prevalence of calcific aortic valve disease (CAVD) remains substantial while there is currently no medical therapy available. Forkhead box O1 (FOXO1) is known to be involved in the pathogenesis of cardiovascular diseases, including vascular calcification and atherosclerosis; however, its specific role in calcific aortic valve disease remains to be elucidated. In this study, we identified FOXO1 significantly down-regulated in the aortic valve interstitial cells (VICs) of calcified aortic valves by investigating clinical specimens and GEO database analysis. FOXO1 silencing or inhibition promoted VICs osteogenic differentiation in vitro and aortic valve calcification in Apoe-/- mice, respectively. We identified that FOXO1 facilitated the ubiquitination and degradation of RUNX2, which process was mainly mediated by SMAD-specific E3 ubiquitin ligase 2 (SMURF2). Our discoveries unveil a heretofore unacknowledged mechanism involving the FOXO1/SMURF2/RUNX2 axis in CAVD, thereby proposing the potential therapeutic utility of FOXO1 or SMURF2 as viable strategies to impede the progression of CAVD.

Vascular calcification and cellular signaling pathways as potential therapeutic targets

Increased vascular calcification (VC) is observed in patients with cardiovascular diseases such as atherosclerosis, diabetes, and chronic kidney disease. VC is divided into three types according to its location: intimal, medial, and valvular. Various cellular signaling pathways are associated with VC, including the Wnt, mitogen-activated protein kinase, phosphatidylinositol-3 kinase/Akt, cyclic nucleotide-dependent protein kinase, protein kinase C, calcium/calmodulin-dependent kinase II, adenosine monophosphate-activated protein kinase/mammalian target of rapamycin, Ras homologous GTPase, apoptosis, Notch, and cytokine signaling pathways. In this review, we discuss the literature concerning the key cellular signaling pathways associated with VC and their role as potential therapeutic targets. Inhibitors to these pathways represent good candidates for use as potential therapeutic agents for the prevention and treatment of VC.

Wnt16 Promotes Vascular Smooth Muscle Contractile Phenotype and Function via Taz (Wwtr1) Activation in Male LDLR-/- Mice

Wnt16 is expressed in bone and arteries, and maintains bone mass in mice and humans, but its role in cardiovascular physiology is unknown. We show that Wnt16 protein accumulates in murine and human vascular smooth muscle (VSM). WNT16 genotypes that convey risk for bone frailty also convey risk for cardiovascular events in the Dallas Heart Study. Murine Wnt16 deficiency, which causes postnatal bone loss, also reduced systolic blood pressure. Electron microscopy demonstrated abnormal VSM mitochondrial morphology in Wnt16-null mice, with reductions in mitochondrial respiration. Following angiotensin-II (AngII) infusion, thoracic ascending aorta (TAA) dilatation was greater in Wnt16-/- vs Wnt16+/+ mice (LDLR-/- background). Acta2 (vascular smooth muscle alpha actin) deficiency has been shown to impair contractile phenotype and worsen TAA aneurysm with concomitant reductions in blood pressure. Wnt16 deficiency reduced expression of Acta2, SM22 (transgelin), and other contractile genes, and reduced VSM contraction induced by TGFβ. Acta2 and SM22 proteins were reduced in Wnt16-/- VSM as was Ankrd1, a prototypic contractile target of Yap1 and Taz activation via TEA domain (TEAD)-directed transcription. Wnt16-/- VSM exhibited reduced nuclear Taz and Yap1 protein accumulation. SiRNA targeting Wnt16 or Taz, but not Yap1, phenocopied Wnt16 deficiency, and Taz siRNA inhibited contractile gene upregulation by Wnt16. Wnt16 incubation stimulated mitochondrial respiration and contraction (reversed by verteporfin, a Yap/Taz inhibitor). SiRNA targeting Taz inhibitors Ccm2 and Lats1/2 mimicked Wnt16 treatment. Wnt16 stimulated Taz binding to Acta2 chromatin and H3K4me3 methylation. TEAD cognates in the Acta2 promoter conveyed transcriptional responses to Wnt16 and Taz. Wnt16 regulates cardiovascular physiology and VSM contractile phenotype, mediated via Taz signaling.

Roles of Vascular Smooth Muscle Cells in Atherosclerotic Calcification

The accumulation of calcium in atherosclerotic plaques is a prominent feature of advanced atherosclerosis, and it has a strong positive correlation with the total burden of atherosclerosis. Atherosclerotic calcification usually appears first at the necrotic core, indicating that cell death and inflammatory processes are involved in calcification. During atherosclerotic inflammation, various cell types, such as vascular smooth muscle cells, nascent resident pericytes, circulating stem cells, or adventitial cells, have been assumed to differentiate into osteoblastic cells, which lead to vascular calcification. Among these cell types, vascular smooth muscle cells are considered a major contributor to osteochondrogenic cells in the atherosclerotic milieu. In this review, we summarize the molecular mechanisms underlying the osteochondrogenic switch of vascular smooth muscle cells in atherosclerotic plaques.

Molecular Mechanisms of Vascular Health: Insights From Vascular Aging and Calcification

Cardiovascular disease is the most common cause of death worldwide, especially beyond the age of 65 years, with the vast majority of morbidity and mortality due to myocardial infarction and stroke. Vascular pathology stems from a combination of genetic risk, environmental factors, and the biologic changes associated with aging. The pathogenesis underlying the development of vascular aging, and vascular calcification with aging, in particular, is still not fully understood. Accumulating data suggests that genetic risk, likely compounded by epigenetic modifications, environmental factors, including diabetes and chronic kidney disease, and the plasticity of vascular smooth muscle cells to acquire an osteogenic phenotype are major determinants of age-associated vascular calcification. Understanding the molecular mechanisms underlying genetic and modifiable risk factors in regulating age-associated vascular pathology may inspire strategies to promote healthy vascular aging. This article summarizes current knowledge of concepts and mechanisms of age-associated vascular disease, with an emphasis on vascular calcification.

Non-canonical WNT signalling in cardiovascular disease: mechanisms and therapeutic implications

WNT signalling comprises a diverse spectrum of receptor-mediated pathways activated by a large family of WNT ligands and influencing fundamental biological processes. WNT signalling includes the β-catenin canonical pathway and the non-canonical pathways, namely the planar cell polarity and the calcium-dependent pathways. Advances over the past decade have linked non-canonical WNT signalling with key mechanisms of atherosclerosis, including oxidative stress, endothelial dysfunction, macrophage activation and vascular smooth muscle cell phenotype regulation. In addition, non-canonical WNT signalling is involved in crucial aspects of myocardial biology, from fibrosis to hypertrophy and oxidative stress. Importantly, non-canonical WNT signalling activation has complex effects in adipose tissue in the context of obesity, thereby potentially linking metabolic and vascular diseases. Tissue-specific targeting of non-canonical WNT signalling might be associated with substantial risks of off-target tumorigenesis, challenging its therapeutic potential. However, novel technologies, such as monoclonal antibodies, recombinant decoy receptors, tissue-specific gene silencing with small interfering RNAs and gene editing with CRISPR-Cas9, might enable more efficient therapeutic targeting of WNT signalling in the cardiovascular system. In this Review, we summarize the components of non-canonical WNT signalling, their links with the main mechanisms of atherosclerosis, heart failure and arrhythmias, and the rationale for targeting individual components of non-canonical WNT signalling for the treatment of cardiovascular disease.

Histone modification in podocyte injury of diabetic nephropathy

Diabetic nephropathy (DN), an important complication of diabetic microvascular disease, is one of the leading causes of end-stage renal disease (ESRD), which brings heavy burdens to the whole society. Podocytes are terminally differentiated glomerular cells, which act as a pivotal component of glomerular filtration barrier. When podocytes are injured, glomerular filtration barrier is damaged, and proteinuria would occur. Dysfunction of podocytes contributes to DN. And degrees of podocyte injury influence prognosis of DN. Growing evidences have shown that epigenetics does a lot in the evolvement of podocyte injury. Epigenetics includes DNA methylation, histone modification, and non-coding RNA. Among them, histone modification plays an indelible role. Histone modification includes histone methylation, histone acetylation, and other modifications such as histone phosphorylation, histone ubiquitination, histone ADP-ribosylation, histone crotonylation, and histone β-hydroxybutyrylation. It can affect chromatin structure and regulate gene transcription to exert its function. This review is to summarize documents about pathogenesis of podocyte injury, most importantly, histone modification of podocyte injury in DN recently to provide new ideas for further molecular research, diagnosis, and treatment.

Skeletal and extraskeletal disorders of biomineralization

The physiological process of biomineralization is complex and deviation from it leads to a variety of diseases. Progress in the past 10 years has enhanced understanding of the genetic, molecular and cellular pathophysiology underlying these disorders; sometimes, this knowledge has both facilitated restoration of health and clarified the very nature of biomineralization as it occurs in humans. In this Review, we consider the principal regulators of mineralization and crystallization, and how dysregulation of these processes can lead to human disease. The knowledge acquired to date and gaps still to be filled are highlighted. The disorders of mineralization discussed comprise a broad spectrum of conditions that encompass bone disorders associated with alterations of mineral quantity and quality, as well as disorders of extraskeletal mineralization (hyperphosphataemic familial tumoural calcinosis). Included are disorders of alkaline phosphatase (hypophosphatasia) and phosphate homeostasis (X-linked hypophosphataemic rickets, fluorosis, rickets and osteomalacia). Furthermore, crystallopathies are covered as well as arterial and renal calcification. This Review discusses the current knowledge of biomineralization derived from basic and clinical research and points to future studies that will lead to new therapeutic approaches for biomineralization disorders.

LRP6 Polymorphisms Is Associated With Sudden Cardiac Death in Patients With Chronic Heart Failure in the Chinese Han Population

Low-density lipoprotein receptor-related protein 6 (LRP6) plays a critical role in cardiovascular homeostasis. The deficiency of LRP6 is associated with a high risk of arrhythmias. However, the association between genetic variations of LRP6 and sudden cardiac death (SCD) remains unknown. This study aims to explore the association between common variants of LRP6 and the prognosis of chronic heart failure (CHF) patients. From July 2005 to December 2009, patients with CHF were enrolled from 10 hospitals in China. The single-nucleotide polymorphism (SNP) rs2302684 was selected for the evaluation of the effect of LRP6 polymorphisms on the survival in patients with CHF. A total of 1,437 patients with CHF were finally included for the analysis. During a median follow-up of 61 months (range 0.4–129 months), a total of 546 (38.0%) patients died, including 201 (36.8%) cases with SCD and 345 (63.2%) cases with non-SCD. Patients carrying A allele of rs2302684 had an increased risk of all-cause death (adjusted HR 1.452, 95% CI 1.189–1.706; P < 0.001) and SCD (adjusted HR 1.783, 95% CI 1.337–2.378; P < 0.001). Therefore, the SNP rs2302684 T>A in LRP6 indicated higher risks of all-cause death and SCD in patients with CHF. LRP6 could be added as a novel predictor of SCD and might be a potential therapeutic target in the prevention of SCD in the CHF population.

X-box Binding Protein 1: An Adaptor in the Pathogenesis of Atherosclerosis

Atherosclerosis (AS), the formation of fibrofatty lesions in the vessel wall, is the primary cause of heart disease and stroke and is closely associated with aging. Disrupted metabolic homeostasis is a primary feature of AS and leads to endoplasmic reticulum (ER) stress, which is an abnormal accumulation of unfolded proteins. By orchestrating signaling cascades of the unfolded protein response (UPR), ER stress functions as a double-edged sword in AS, where adaptive UPR triggers synthetic metabolic processes to restore homeostasis, whereas the maladaptive response programs the cell to the apoptotic pathway. However, little is known regarding their precise coordination. Herein, an advanced understanding of the role of UPR in the pathological process of AS is reviewed. In particular, we focused on a critical mediator of the UPR, X-box binding protein 1 (XBP1), and its important role in balancing adaptive and maladaptive responses. The XBP1 mRNA is processed from the unspliced isoform (XBP1u) to the spliced isoform of XBP1 (XBP1s). Compared with XBP1u, XBP1s predominantly functions downstream of inositol-requiring enzyme-1α (IRE1α) and transcript genes involved in protein quality control, inflammation, lipid metabolism, carbohydrate metabolism, and calcification, which are critical for the pathogenesis of AS. Thus, the IRE1α/XBP1 axis is a promising pharmaceutical candidate against AS.

Inducible Prmt1 ablation in adult vascular smooth muscle leads to contractile dysfunction and aortic dissection

Vascular smooth muscle cells (VSMCs) have remarkable plasticity in response to diverse environmental cues. Although these cells are versatile, chronic stress can trigger VSMC dysfunction, which ultimately leads to vascular diseases such as aortic aneurysm and atherosclerosis. Protein arginine methyltransferase 1 (Prmt1) is a major enzyme catalyzing asymmetric arginine dimethylation of proteins that are sources of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase. Although a potential role of Prmt1 in vascular pathogenesis has been proposed, its role in vascular function has yet to be clarified. Here, we investigated the role and underlying mechanism of Prmt1 in vascular smooth muscle contractility and function. The expression of PRMT1 and contractile-related genes was significantly decreased in the aortas of elderly humans and patients with aortic aneurysms. Mice with VSMC-specific Prmt1 ablation (smKO) exhibited partial lethality, low blood pressure and aortic dilation. The Prmt1-ablated aortas showed aortic dissection with elastic fiber degeneration and cell death. Ex vivo and in vitro analyses indicated that Prmt1 ablation significantly decreased the contractility of the aorta and traction forces of VSMCs. Prmt1 ablation downregulated the expression of contractile genes such as myocardin while upregulating the expression of synthetic genes, thus causing the contractile to synthetic phenotypic switch of VSMCs. In addition, mechanistic studies demonstrated that Prmt1 directly regulates myocardin gene activation by modulating epigenetic histone modifications in the myocardin promoter region. Thus, our study demonstrates that VSMC Prmt1 is essential for vascular homeostasis and that its ablation causes aortic dilation/dissection through impaired myocardin expression.

Interaction of SOX5 with SOX9 promotes warfarin-induced aortic valve interstitial cell calcification by repressing transcriptional activation of LRP6

Calcific aortic valve disease (CAVD) is an important health burden due to its increasing prevalence and lack of available approaches. Osteogenic transdifferentiation of aortic valve interstitial cells (AVICs) contributes to valve calcification. SRY-related HMG-box transcription factor 5 (SOX5) is essential for cartilage development. Whether SOX5 is involved in AVIC calcification has not been determined. This study aimed to explore the role of SOX5 in warfarin-induced AVIC calcification. Immunostaining showed decreased SOX5 in human calcific AV and warfarin induced mouse calcific AV tissues compared with human noncalcific AV and control mouse AV tissues. In calcific human AVICs (hAVICs) and porcine AVICS (pAVICs), both knockdown and overexpression of SOX5 inhibited calcium deposition and osteogenic marker gene expression. Protein expression assays and ChIP assays showed that overexpression of SOX5 led to increased recruitment of SOX5 to the SOX9 promoter and resulted in increased mRNA and protein expression of SOX9. Coimmunoprecipitation and immunofluorescence showed that SOX5 binds to SOX9 with its HMG domain in nucleus. Blue Native PAGE showed overexpression of SOX5 led to multimeric complex formation of SOX5 and resulted in decreased binding of SOX5 to SOX9 similar to the results of knockdown of SOX5. Further ChIP and western blotting assays showed that both knockdown and overexpression of SOX5 resulted in SOX9 initiating transcription of anti-calcific gene LRP6 in warfarin-treated pAVICs. Knockdown of LRP6 rescues the anti-calcification effect of SOX5 overexpression. We found that both loss and gain of function of SOX5 lead to the same phenotype: decreased warfarin induced calcification. The stoichiometry of SOX5 is crucial for cooperation with SOX9, SOX9 nuclear localization and subsequent binding of SOX9 to LRP6 promoter. These results suggest that SOX5 is a potential target for the development of anti-calcification therapy.

Novel insights into the pathological mechanisms of metabolic related dyslipidemia

Due to the technological advances, it has been well-established that obesity is strongly correlated with various health problems. Among these problems, dyslipidemia is one of the most important concomitant symptoms under obese status which is the main driving force behind the pathological progression of cardio-metabolic disorder diseases. Importantly, the type of dyslipidemia, arising from concerted action of obesity, has been identified as "metabolic related dyslipidemia", which is characterized by increased circulating levels of Low density lipoprotein cholesterol (LDL-C), Triglycerides (TG) accompanied by lower circulating levels of High density lipoprotein cholesterol (HDL-C). On the other hand, the metabolic related dyslipidemia is being verified as a vital link between obesity and hypertension, diabetes mellitus, and Cardiovascular disease (CVD). In this review, we summarized the current understanding of metabolic related dyslipidemia and the potential mechanisms which lead to the pathogenesis of obesity. Meanwhile, we also summarized the emerging results which focused on several novel lipid bio-markers in metabolic related dyslipidemia, such as pro-protein convertase subtilisin/kexin type 9 (PCSK9) and sphingosine-1-phosphate (S1P), and their potential use as biomarkers of metabolic related dyslipidemia.

Pathology of metabolically-related dyslipidemia

It is well established that overweight/obesity is closely associated with multiple health problems. Among these, dyslipidemia is the most important and main driving force behind pathologic development of cardio-metabolic disorders such as diabetes mellitus, atherosclerotic-related cardiovascular disease and hypertension. Notably, a subtype of dyslipidemia, metabolic related dyslipidemia, is now recognized as a vital link between obesity and multiple different cardiovascular diseases. This condition is characterized by increased low density lipoprotein cholesterol (LDL-C) and triglyceride (TG) and very low density lipoprotein cholesterol (VLDL-C) as well as decreased high density lipoprotein cholesterol (HDL-C) in serum. In this review, we summarize the current understanding of metabolic related dyslipidemia and the potential mechanisms which lead to the pathogenesis of obesity/overweight. We focus on several novel lipid biomarkers such as pro-protein convertase subtilisin/kexin type 9 (PCSK9) and sphingosine-1-phosphate (S1P) and their potential use as biomarkers of metabolic related dyslipidemia.

The complex role of Wnt ligands in type 2 diabetes mellitus and related complications

Type 2 diabetes mellitus (T2DM) is one of the major chronic diseases, whose prevalence is increasing dramatically worldwide and can lead to a range of serious complications. Wnt ligands (Wnts) and their activating Wnt signalling pathways are closely involved in the regulation of various processes that are important for the occurrence and progression of T2DM and related complications. However, our understanding of their roles in these diseases is quite rudimentary due to the numerous family members of Wnts and conflicting effects via activating the canonical and/or non-canonical Wnt signalling pathways. In this review, we summarize the current findings on the expression pattern and exact role of each human Wnt in T2DM and related complications, including Wnt1, Wnt2, Wnt2b, Wnt3, Wnt3a, Wnt4, Wnt5a, Wnt5b, Wnt6, Wnt7a, Wnt7b, Wnt8a, Wnt8b, Wnt9a, Wnt9b, Wnt10a, Wnt10b, Wnt11 and Wnt16. Moreover, the role of main antagonists (sFRPs and WIF-1) and coreceptor (LRP6) of Wnts in T2DM and related complications and main challenges in designing Wnt-based therapeutic approaches for these diseases are discussed. We hope a deep understanding of the mechanistic links between Wnt signalling pathways and diabetic-related diseases will ultimately result in a better management of these diseases.

Wnt/β-catenin signaling: Structure, assembly and endocytosis of the signalosome

Wnt/β‐catenin signaling is an ancient pathway that regulates key aspects of embryonic development, cell differentiation, proliferation, and adult stem cell homeostasis. Work from different laboratories has shed light on the molecular mechanisms underlying the Wnt pathway, including structural details of ligand–receptor interactions. One key aspect that has emerged from multiple studies is that endocytosis of the receptor complex plays a crucial role in fine‐tuning Wnt/β‐catenin signaling. Endocytosis is a key process involved in both activation as well as attenuation of Wnt signaling, but how this is regulated is still poorly understood. Importantly, recent findings show that Wnt also regulates central metabolic pathways such as the acquisition of nutrients through actin‐driven endocytic mechanisms. In this review, we propose that the Wnt pathway displays diverse characteristics that go beyond the regulation of gene expression, through a connection with the endocytic machinery.

Wnt Signaling Cascades and Their Role in Coronary Artery Health and Disease

The Wnt signaling is classified as two distinct pathways of canonical Wnt/β-catenin signaling, and the non-canonical pathways of planar cell polarity and Wnt/Ca²⁺ pathways. However, the scientific discoveries in recent years have shown that canonical and non-canonical Wnts pathways are intertwined and have complex interaction with other major signaling pathways such as hedgehog, Hippo and TOR signaling. Wnt signaling plays important roles in cell proliferation, differentiation and migration during embryonic development. The impairment of these pathways during embryonic development often leads to major congenital defects. In adult organisms Wnt expression is more restricted to proliferating tissues, where it plays a key role in tissue regeneration. In addition, the disruption of homeostatic processes of multicellular organisms may give rise to reactivation and/or altered activation of Wnt signaling, leading to development of malignant tumors and chronic diseases such as type-2 diabetes and adult cardiovascular diseases.

Coronary artery disease (CAD) is the leading cause of death in the world. The disease is the consequences of two distinct disease processes: Atherosclerosis, a primarily inflammatory disease and plaque erosion, a disease process associated with endothelial cell defect and smooth muscle proliferation with only modest contribution of inflammatory cells. The atherosclerosis is itself a multifactorial disease that is initiated by lipid deposition and endothelial dysfunction, triggering vascular inflammation via recruitment and aggregation of monocytes and their transformation to foam cell by the uptake of modified low-density lipoprotein (LDL), culminating in an atheromatous plaque core formation. Further accumulation of lipids, infiltration and proliferation of vascular smooth muscle cells (VSMCs) and extracellular matrix deposition result in intimal hyperplasia. Myocardial infarction is the ultimate consequence of these processes and is caused by plaque rupture and hypercoagulation. In vivo studies have established the role of the Wnt pathway in all phases of atherosclerosis development, though much remains unknown or controversial. Less is known about the mechanisms that induce plaque erosion. The limited evidence in mouse models of Wnt coreceptor LRP6 mutation and heterozygous TCF7L2 knock out mice implicate altered Wnt signaling also in the pathogenesis of plaque erosion. In this article we focus and review the role of the Wnt pathway in CAD pathophysiology from clinical and experimental standpoints.

Lipoprotein receptor signalling in atherosclerosis

The founding member of the lipoprotein receptor family, low-density lipoprotein receptor (LDLR) plays a major role in the atherogenesis through the receptor-mediated endocytosis of LDL particles and regulation of cholesterol homeostasis. Since the discovery of the LDLR, many other structurally and functionally related receptors have been identified, which include low-density lipoprotein receptor-related protein (LRP)1, LRP5, LRP6, very low-density lipoprotein receptor, and apolipoprotein E receptor 2. The scavenger receptor family members, on the other hand, constitute a family of pattern recognition proteins that are structurally diverse and recognize a wide array of ligands, including oxidized LDL. Among these are cluster of differentiation 36, scavenger receptor class B type I and lectin-like oxidized low-density lipoprotein receptor-1. In addition to the initially assigned role as a mediator of the uptake of macromolecules into the cell, a large number of studies in cultured cells and in in vivo animal models have revealed that these lipoprotein receptors participate in signal transduction to modulate cellular functions. This review highlights the signalling pathways by which these receptors influence the process of atherosclerosis development, focusing on their roles in the vascular cells, such as macrophages, endothelial cells, smooth muscle cells, and platelets. Human genetics of the receptors is also discussed to further provide the relevance to cardiovascular disease risks in humans. Further knowledge of the vascular biology of the lipoprotein receptors and their ligands will potentially enhance our ability to harness the mechanism to develop novel prophylactic and therapeutic strategies against cardiovascular diseases.

ERK1/2 inhibition reduces vascular calcification by activating miR-126-3p-DKK1/LRP6 pathway

Rationale: Vascular microcalcification increases the risk of rupture of vulnerable atherosclerotic lesions. Inhibition of ERK1/2 reduces atherosclerosis in animal models while its role in vascular calcification and the underlying mechanisms remains incompletely understood.

Methods: Levels of activated ERK1/2, DKK1, LRP6 and BMP2 in human calcific aortic valves were determined. ApoE deficient mice received ERK1/2 inhibitor (U0126) treatment, followed by determination of atherosclerosis, calcification and miR-126-3p production. C57BL/6J mice were used to determine the effect of U0126 on Vitamin D₃ (VD₃)-induced medial arterial calcification. HUVECs, HAECs and HASMCs were used to determine the effects of ERK1/2 inhibitor or siRNA on SMC calcification and the involved mechanisms.

Results: We observed the calcification in human aortic valves was positively correlated to ERK1/2 activity. At cellular and animal levels, U0126 reduced intimal calcification in atherosclerotic lesions of high-fat diet-fed apoE deficient mice, medial arterial calcification in VD₃-treated C57BL/6J mice, and calcification in cultured SMCs and arterial rings. The reduction of calcification was attributed to ERK1/2 inhibition-reduced expression of ALP, BMP2 and RUNX2 by activating DKK1 and LRP6 expression, and consequently inactivating both canonical and non-canonical Wnt signaling pathways in SMCs. Furthermore, we determined ERK1/2 inhibition activated miR-126-3p production by facilitating its maturation through activation of AMPKα-mediated p53 phosphorylation, and the activated miR-126-3p from ECs and SMCs played a key role in anti-vascular calcification actions of ERK1/2 inhibition.

Conclusions: Our study demonstrates that activation of miR-126-3p production in ECs/SMCs and interactions between ECs and SMCs play an important role in reduction of vascular calcification by ERK1/2 inhibition.

YAP/TAZ Are Required to Suppress Osteogenic Differentiation of Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) represent the prevailing cell type of arterial vessels and are essential for blood vessel structure and homeostasis. They have substantial potential for phenotypic plasticity when exposed to various stimuli in their local microenvironment. How VSMCs maintain their differentiated contractile phenotype is still poorly understood. Here we demonstrate that the Hippo pathway effectors YAP and TAZ play a critical role in maintaining the differentiated contractile phenotype of VSMCs. In the absence of YAP/TAZ, VSMCs lose their differentiated phenotype and undergo osteogenic differentiation, which results in vascular calcification. Osteogenic transdifferentiation was accompanied by the upregulation of Wnt target genes. The absence of YAP/TAZ in VSMCs led to Disheveled 3 (DVL3) nuclear translocation and upregulation of osteogenesis-associated genes independent of canonical Wnt/β-catenin signaling activation. Our data indicate that cytoplasmic YAP/TAZ interact with DVL3 to avoid its nuclear translocation and osteogenic differentiation, thereby maintaining the differentiated phenotype of VSMCs.

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YAP/TAZ play an important role in maintaining vascular SMCs contractile phenotype

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Loss of YAP/TAZ in vSMCs leads to reduced expression of smooth muscle marker genes

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Loss of YAP/TAZ in vSMCs results in reduced artery contractility

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Deficiency of YAP/TAZ in vSMCs leads to osteogenic transdifferentiation

Lysolipids in Vascular Development, Biology, and Disease

Membrane phospholipid metabolism forms lysophospholipids, which possess unique biochemical and biophysical properties that influence membrane structure and dynamics. However, lysophospholipids also function as ligands for G-protein-coupled receptors that influence embryonic development, postnatal physiology, and disease. The 2 most well-studied species-lysophosphatidic acid and S1P (sphingosine 1-phosphate)-are particularly relevant to vascular development, physiology, and cardiovascular diseases. This review summarizes the role of lysophosphatidic acid and S1P in vascular developmental processes, endothelial cell biology, and their roles in cardiovascular disease processes. In addition, we also point out the apparent connections between lysophospholipid biology and the Wnt (int/wingless family) pathway, an evolutionarily conserved fundamental developmental signaling system. The discovery that components of the lysophospholipid signaling system are key genetic determinants of cardiovascular disease has warranted current and future research in this field. As pharmacological approaches to modulate lysophospholipid signaling have entered the clinical sphere, new findings in this field promise to influence novel therapeutic strategies in cardiovascular diseases.

Wnt-inducible Lrp6-APEX2 interacting proteins identify ESCRT machinery and Trk-fused gene as components of the Wnt signaling pathway

The canonical Wnt pathway serves as a hub connecting diverse cellular processes, including β-catenin signaling, differentiation, growth, protein stability, macropinocytosis, and nutrient acquisition in lysosomes. We have proposed that sequestration of β-catenin destruction complex components in multivesicular bodies (MVBs) is required for sustained canonical Wnt signaling. In this study, we investigated the events that follow activation of the canonical Wnt receptor Lrp6 using an APEX2-mediated proximity labeling approach. The Wnt co-receptor Lrp6 was fused to APEX2 and used to biotinylate targets that are recruited near the receptor during Wnt signaling at different time periods. Lrp6 proximity targets were identified by mass spectrometry, and revealed that many endosomal proteins interacted with Lrp6 within 5 min of Wnt3a treatment. Interestingly, we found that Trk-fused gene (TFG), previously known to regulate the cell secretory pathway and to be rearranged in thyroid and lung cancers, was strongly enriched in the proximity of Lrp6. TFG depletion with siRNA, or knock-out with CRISPR/Cas9, significantly reduced Wnt/β-catenin signaling in cell culture. In vivo, studies in the Xenopus system showed that TFG is required for endogenous Wnt-dependent embryonic patterning. The results suggest that the multivesicular endosomal machinery and the novel player TFG have important roles in Wnt signaling.

Omics research in vascular calcification

Vascular calcification (VC), the pathological process of hydroxyapatite mineral deposition in the vascular system, is closely associated with aging, atherosclerotic plaque formation, cardiovascular disease (CVD) and diabetes mellitus (DM). Studies have shown that VC is related to cellular phenotypic changes, extracellular vesicles, disordered calcium and phosphate homeostasis, and an imbalance between inducers and inhibitors of VC. Unfortunately, there is currently no effective preventive or targeted treatment for pathologic condition. The rapid evolution of omics technology (genomics, epigenomics, transcriptomics, proteomics and metabolomics) has provided a novel approach for elucidation of pathophysiologic mechanisms in general and those associated with VC specifically. Here, we review articles published over the last twenty years and focus on the current state, challenges, limitations and future of omics in VC research and clinical practice. Highlighting potential targets based on omics technology will improve our understanding of this pathologic condition and assist in the development of potential treatment options for VC related disease.

Omics research in vascular calcification

Vascular calcification (VC), the pathological process of hydroxyapatite mineral deposition in the vascular system, is closely associated with aging, atherosclerotic plaque formation, cardiovascular disease (CVD) and diabetes mellitus (DM). Studies have shown that VC is related to cellular phenotypic changes, extracellular vesicles, disordered calcium phosphate homeostasis and an imbalance between inducers and inhibitors of VC. Unfortunately, there is currently no effective preventive or targeted treatment for this disorder. Recently, the evolution of omics technology (genomics, epigenomics, transcriptomics, proteomics and metabolomics) has paved the way for elucidation of complex biochemical processes and, as such, may provide new insight on VC. Accordingly, we conducted a review of articles published over the last twenty years and herein focus on current and future potential of omics technology in clarifying mechanisms of this disease process. Identification of new biomarkers will provide additional tools in characterizing this pathology and will further assist in the development of potential therapeutic targets.

The role of Wnt signalling in development of coronary artery disease and its risk factors

The Wnt signalling pathways are composed of a highly conserved cascade of events that govern cell differentiation, apoptosis and cell orientation. Three major and distinct Wnt signalling pathways have been characterized: the canonical Wnt pathway (or Wnt/β-catenin pathway), the non-canonical planar cell polarity pathway and the non-canonical Wnt/Ca2+ pathway. Altered Wnt signalling pathway has been associated with diverse diseases such as disorders of bone density, different malignancies, cardiac malformations and heart failure. Coronary artery disease is the most common type of heart disease in the United States. Atherosclerosis is a multi-step pathological process, which starts with lipid deposition and endothelial cell dysfunction, triggering inflammatory reactions, followed by recruitment and aggregation of monocytes. Subsequently, monocytes differentiate into tissue-resident macrophages and transform into foam cells by the uptake of modified low-density lipoprotein. Meanwhile, further accumulations of lipids, infiltration and proliferation of vascular smooth muscle cells, and deposition of the extracellular matrix occur under the intima. An atheromatous plaque or hyperplasia of the intima and media is eventually formed, resulting in luminal narrowing and reduced blood flow to the myocardium, leading to chest pain, angina and even myocardial infarction. The Wnt pathway participates in all different stages of this process, from endothelial dysfunction to lipid deposit, and from initial inflammation to plaque formation. Here, we focus on the role of Wnt cascade in pathophysiological mechanisms that take part in coronary artery disease from both clinical and experimental perspectives.

Emerging functions of adipokines in linking the development of obesity and cardiovascular diseases

Increasing evidence shows that obesity is the critical factor in shaping cardio-metabolic phenotypes. However, the pathogenic mechanisms remain incompletely clarified. According to the published reports, adipose tissue communicates with several diverse organs, such as heart, lungs, and kidneys through the secretion of various cytokines named adipokines. The adipocytes isolated from obese mice or humans are dysfunctional with aberrant production of pro-inflammatory adipokines, which subsequently induce both acute and chronic inflammatory reaction and facilitate the process of cardio-metabolic disorder complications. Furthermore, the microenvironment within adipose tissue under obese status also influence the secretion of adipokines. Recently, given that several important adipokines have been completely researched and causally involved in various diseases, we could make a conclusion that adipokines play an essential role in modulating the development of cardio-metabolic disorder diseases, whereas several novel adipokines continue to be explored and elucidated. In the present review, we summarized the current knowledge of the microenvironment of adipose tissue and the published mechanisms whereby adipocytes affects obesity and cardiovascular diseases. On the other hand, we also provide the evidence to elucidate the functions of adipokines in controlling and regulating the inflammatory reactions which contribute to obesity and cardiovascular disease.

Sclerostin is an independent risk factor for all-cause mortality in kidney transplant recipients

Background

Sclerostin is a hormone contributing to the bone-vascular wall cross talk and has been implicated in cardiovascular events and mortality in patients with chronic kidney disease (CKD). We analyzed the relationship between sclerostin and mortality in renal transplant recipients.

Methods

600 stable renal transplant recipients (367men, 233 women) were followed for all-cause mortality for 3 years. Blood and urine samples for analysis and clinical data were collected at study entry. We performed Kaplan–Meier survival analysis and Cox regression models considering confounding factors such as age, eGFR, cold ischemia time, HbA1c, phosphate, calcium, and albumin. Optimal cut-off values for the Cox regression model were calculated based on ROC analysis.

Results

Sixty-five patients died during the observation period. Nonsurvivors (n = 65; sclerostin 57.31 ± 30.28 pmol/L) had higher plasma sclerostin levels than survivors (n = 535; sclerostin 47.52 ± 24.87 pmol/L) (p = 0.0036). Kaplan–Meier curve showed that baseline plasma sclerostin concentrations were associated with all-cause mortality in stable kidney transplant recipients (p = 0.0085, log-rank test). After multiple Cox regression analysis, plasma levels of sclerostin remained an independent predictor of all-cause mortality (hazard ratio, 1.011; 95% CI 1.002–1.020; p = 0.0137).

Conclusions

Baseline plasma sclerostin is an independent risk factor for all-cause mortality in patients after kidney transplantation.

Electronic supplementary material

The online version of this article (10.1007/s10157-020-01956-y) contains supplementary material, which is available to authorized users.

DDR1 (Discoidin Domain Receptor-1)-RhoA (Ras Homolog Family Member A) Axis Senses Matrix Stiffness to Promote Vascular Calcification

Supplemental Digital Content is available in the text.

Objective:

Vascular calcification is a pathology characterized by arterial mineralization, which is a common late-term complication of atherosclerosis that independently increases the risk of adverse cardiovascular events by fourfold. A major source of calcifying cells is transdifferentiating vascular smooth muscle cells (VSMCs). Previous studies showed that deletion of the collagen-binding receptor, DDR1 (discoidin domain receptor-1), attenuated VSMC calcification. Increased matrix stiffness drives osteogenesis, and DDR1 has been implicated in stiffness sensing in other cell types; however, the role of DDR1 as a mechanosensor in VSMCs has not been investigated. Here, we test the hypothesis that DDR1 senses increased matrix stiffness and promotes VSMC transdifferentiation and calcification.

Approach and Results:

Primary VSMCs isolated from Ddr1^+/+ (wild-type) and Ddr1^−/− (knockout) mice were studied on collagen-I–coated silicon substrates of varying stiffness, culturing in normal or calcifying medium. DDR1 expression and phosphorylation increased with increasing stiffness, as did in vitro calcification, nuclear localization of Runx2 (Runt-related transcription factor 2), and expression of other osteochondrocytic markers. By contrast, DDR1 deficient VSMCs were not responsive to stiffness and did not undergo transdifferentiation. DDR1 regulated stress fiber formation and RhoA (ras homolog family member A) activation through the RhoGEF (rho guanine nucleotide exchange factor), Vav2. Inhibition of actomyosin contractility reduced Runx2 activation and attenuated in vitro calcification in wild-type VSMCs. Finally, a novel positive feedforward loop was uncovered between DDR1 and actomyosin contractility, important in regulating DDR1 expression, clustering, and activation.

Conclusions:

This study provides mechanistic insights into DDR1 mechanosignaling and shows that DDR1 activity and actomyosin contractility are interdependent in mediating stiffness-dependent increases in VSMC calcification.

PTH/PTHrP Receptor Signaling Restricts Arterial Fibrosis in Diabetic LDLR-/- Mice by Inhibiting Myocardin-Related Transcription Factor Relays

RATIONALE

The PTH1R (PTH [parathyroid hormone]/PTHrP [PTH-related protein] receptor) is expressed in vascular smooth muscle (VSM) and increased VSM PTH1R signaling mitigates diet-induced arteriosclerosis in LDLR-/- mice.

OBJECTIVE

To study the impact of VSM PTH1R deficiency, we generated mice SM22-Cre:PTH1R(fl/fl);LDLR-/- mice (PTH1R-VKO) and Cre-negative controls.

METHODS AND RESULTS

Immunofluorescence and Western blot confirmed PTH1R expression in arterial VSM that was reduced by Cre-mediated knockout. PTH1R-VKO cohorts exhibited increased aortic collagen accumulation in vivo, and VSM cultures from PTH1R-VKO mice elaborated more collagen (2.5-fold; P=0.01) with elevated Col3a1 and Col1a1 expression. To better understand these profibrotic responses, we performed mass spectrometry on nuclear proteins extracted from Cre-negative controls and PTH1R-VKO VSM. PTH1R deficiency reduced Gata6 but upregulated the MADS (MCM1, Agamous, Deficiens, and Srf DNA-binding domain)-box transcriptional co-regulator, Mkl-1 (megakaryoblastic leukemia [translocation] 1). Co-transfection assays (Col3a1 promoter-luciferase reporter) confirmed PTH1R-mediated inhibition and Mkl-1-mediated activation of Col3a1 transcription. Regulation mapped to a conserved hybrid CT(A/T)6GG MADS-box cognate in the Col3a1 promoter. Mutations of C/G in this motif markedly reduced Col3a1 transcriptional regulation by PTH1R and Mkl-1. Upregulation of Col3a1 and Col1a1 in PTH1R-VKO VSM was inhibited by small interfering RNA targeting Mkl1 and by treatment with the Mkl-1 antagonist CCG1423 or the Rock (Rho-associated coiled-coil containing protein kinase)-2 inhibitor KD025. Chromatin precipitation demonstrated that VSM PTH1R deficiency increased Mkl-1 binding to Col3a1 and Col1a1, but not TNF, promoters. Proteomic studies of plasma extracellular vesicles and VSM from PTH1R-VKO mice identified C1r (complement component 1, r) and C1s (complement component 1, s), complement proteins involved in vascular collagen metabolism, as potential biomarkers. VSM C1r protein and C1r message were increased with PTH1R deficiency, mediated by Mkl-1-dependent transcription and inhibited by CCG1423 or KD025.

CONCLUSIONS

PTH1R signaling restricts collagen production in the VSM lineage, in part, via Mkl-1 regulatory circuits that control collagen gene transcription. Strategies that maintain homeostatic VSM PTH1R signaling, as reflected in extracellular vesicle biomarkers of VSM PTH1R/Mkl-1 action, may help mitigate arteriosclerosis and vascular fibrosis.

Low-density lipoprotein receptor-related protein 6-mediated signaling pathways and associated cardiovascular diseases: diagnostic and therapeutic opportunities

Low-density lipoprotein receptor-related protein 6 (LRP6) is a member of the low-density lipoprotein receptors (LDLRs) family and accumulating evidence points to the critical role of LRP6 in cardiovascular health and homeostasis. In addition to presenting the well-appreciated roles in canonical signaling regulating blood pressure, blood glucose, lipid metabolism, atherosclerosis, cardiac valve disease, cardiac development, Alzheimer's disease and tumorigenesis, LRP6 also inhibits non-canonical Wnt signals that promote arterial smooth muscle cell proliferation and vascular calcification. Noticeably, the role of LRP6 is displayed in cardiometabolic disease, an increasingly important clinical burden with aging and obesity. The prospect for cardiovascular diseases treatment via targeting LRP6-mediated signaling pathways may improve central blood pressure and lipid metabolism, and reduce neointima formation and myocardial ischemia-reperfusion injury. Thus, a deep and comprehensive understanding of LRP6 structure, function and signaling pathways will contribute to clinical diagnosis, therapy and new drug development for LRP6-related cardiovascular diseases.

Histone methylation and vascular biology

The vasculature not only transports oxygenated blood, metabolites, and waste products but also serves as a conduit for hormonal communication between distant tissues. Therefore, it is important to maintain homeostasis within the vasculature. Recent studies have greatly expanded our understanding of the regulation of vasculature development and vascular-related diseases at the epigenetic level, including by protein posttranslational modifications, DNA methylation, and noncoding RNAs. Integrating epigenetic mechanisms into the pathophysiologic conceptualization of complex and multifactorial vascular-related diseases may provide promising therapeutic approaches. Several reviews have presented detailed discussions of epigenetic mechanisms not including histone methylation in vascular biology. In this review, we primarily discuss histone methylation in vascular development and maturity, and in vascular diseases.

The Epigenetic Landscape of Vascular Calcification: An Integrative Perspective

Vascular calcification (VC) is an important complication among patients of advanced age, those with chronic kidney disease, and those with diabetes mellitus. The pathophysiology of VC encompasses passive occurrence of physico-chemical calcium deposition, active cellular secretion of osteoid matrix upon exposure to metabolically noxious stimuli, or a variable combination of both processes. Epigenetic alterations have been shown to participate in this complex environment, through mechanisms including DNA methylation, non-coding RNAs, histone modifications, and chromatin changes. Despite such importance, existing reviews fail to provide a comprehensive view of all relevant reports addressing epigenetic processes in VC, and cross-talk between different epigenetic machineries is rarely examined. We conducted a systematic review based on PUBMED and MEDLINE databases up to 30 September 2019, to identify clinical, translational, and experimental reports addressing epigenetic processes in VC; we retrieved 66 original studies, among which 60.6% looked into the pathogenic role of non-coding RNA, followed by DNA methylation (12.1%), histone modification (9.1%), and chromatin changes (4.5%). Nine (13.6%) reports examined the discrepancy of epigenetic signatures between subjects or tissues with and without VC, supporting their applicability as biomarkers. Assisted by bioinformatic analyses blending in each epigenetic component, we discovered prominent interactions between microRNAs, DNA methylation, and histone modification regarding potential influences on VC risk.

Wnt Pathway Gene Expression Is Associated With Arterial Stiffness

Background

Animal and in vitro experiments implicate the Wnt pathway in cardiac development, fibrosis, vascular calcification, and atherosclerosis, but research in humans is lacking. We examined peripheral blood Wnt pathway gene expression and arterial stiffness in 369 healthy African ancestry men (mean age, 64 years).

Methods and Results

Gene expression was assessed using a custom Nanostring nCounter gene expression panel (N=43 genes) and normalized to housekeeping genes and background signal. Arterial stiffness was assessed via brachial‐ankle pulse‐wave velocity. Fourteen Wnt genes showed detectable expression and were tested individually as predictors of pulse‐wave velocity using linear regression, adjusting for age, height, weight, blood pressure, medication use, resting heart rate, current smoking, alcohol intake, and sedentary lifestyle. Adenomatous polyposis coli regulator of Wnt signaling pathway (APC), glycogen synthase kinase 3β (GSK3B), and transcription factor 4 (TCF4) were significantly associated with arterial stiffness (P<0.05 for all). When entered into a single model, APC and TCF4 expression remained independently associated with arterial stiffness (P=0.04 and 0.003, respectively), and each explained ≈3% of the variance in pulse‐wave velocity.

Conclusions

The current study establishes a novel association between in vivo expression of the Wnt pathway genes, APC and TCF4, with arterial stiffness in African ancestry men, a population at high risk of hypertensive vascular disease.

Loss of PARP-1 attenuates diabetic arteriosclerotic calcification via Stat1/Runx2 axis

Accelerated atherosclerotic calcification is responsible for plaque burden, especially in diabetes. The regulatory mechanism for atherosclerotic calcification in diabetes is poorly characterized. Here we show that deletion of PARP-1, a main enzyme in diverse metabolic complications, attenuates diabetic atherosclerotic calcification and decreases vessel stiffening in mice through Runx2 suppression. Specifically, PARP-1 deficiency reduces diabetic arteriosclerotic calcification by regulating Stat1-mediated synthetic phenotype switching of vascular smooth muscle cells and macrophage polarization. Meanwhile, both vascular smooth muscle cells and macrophages manifested osteogenic differentiation in osteogenic media, which was attenuated by PARP-1/Stat1 inhibition. Notably, Stat1 acts as a positive transcription factor by directly binding to the promoter of Runx2 and promoting atherosclerotic calcification in diabetes. Our results identify a new function of PARP-1, in which metabolism disturbance-related stimuli activate the Runx2 expression mediated by Stat1 transcription to facilitate diabetic arteriosclerotic calcification. PARP-1 inhibition may therefore represent a useful therapy for this challenging complication.

Expansive Vascular Remodeling and Increased Vascular Calcification Response to Cholecalciferol in a Murine Model of Obesity and Insulin Resistance

Objective- We hypothesized that ob/ob mice develop expansive vascular remodeling associated with calcification. Approach and Results- We quantified and investigated mechanisms of vascular remodeling and vascular calcification in ob/ob mice after vitamin D₃(VD) stimulation or PBS (control), compared with C57BL/6 mice. Both ob/ob (OBVD [VD-treated ob/ob mice]) and C57BL/6 (C57VD [VD-treated C57BL/6 mice]) received 8×10³ IU/day of intraperitoneal VD for 14 days. Control ob/ob (OBCT [PBS-treated ob/ob mice]) and C57BL/6 (C57CT [PBS-treated C57BL/6 mice]) received intraperitoneal PBS for 14 days. Hypervitaminosis D increased the external and internal elastic length in aortae from OBVD, resulting in increased total vascular area and lumen vascular area, respectively, which characterizes expansive vascular remodeling. OBVD decreased the aortic wall thickness, resulting in hypotrophic vascular remodeling. We demonstrated increased collagen deposition, elastolysis, and calcification in aortae from OBVD. Our results showed a positive correlation between expansive vascular remodeling and vascular calcification in OBVD. We demonstrated increased serum calcium levels, augmented Bmp (bone morphogenetic protein)-2 and osteochondrogenic proteins expression in OBVD aortae. Furthermore, aortae from OBVD increased oxidative stress, coincidently with augmented in situ MMP (matrix metalloproteinase) activity and exhibited no VDR (VD receptor) inhibition after VD. Conclusions- Our data provide evidence that obese and insulin-resistant mice (ob/ob) developed expansive hypotrophic vascular remodeling correlated directly with increased vascular calcification after chronic VD stimulation. Positive hypotrophic vascular remodeling and vascular calcification in this mouse model is possibly mediated by the convergence of absence VDR downregulation after VD stimulation, increased reactive oxygen species generation, and MMP activation.

Resveratrol targeting the Wnt signaling pathway: A focus on therapeutic activities

Wingless-type MMTV integration site (Wnt) signaling pathway is considered as an important pathway regulating a variety of biological processes such as tissue formation and homeostasis, cell proliferation, cell migration, cell differentiation, and embryogenesis. Impairment in the Wnt signaling pathway is associated with pathological conditions, particularly cancer. So, modulation of this pathway can be considered as a promising strategy and several drugs have been developed in line with this strategy. Resveratrol (Res) is a naturally occurring nutraceutical compound exclusively found in different fruits and nuts such as grape, peanut, and pistachio. This compound has favorable biological and therapeutic activities such as antioxidant, anti-inflammatory, antitumor, hepatoprotective, cardioprotective, and antidiabetic. At the present review, we demonstrate how Res modulates Wnt signaling pathway to exert its pharmacological effects.

CDC42 promotes vascular calcification in chronic kidney disease

Vascular calcification is prevalent in patients with chronic kidney disease (CKD) and a major risk factor of cardiovascular disease. Vascular calcification is now recognised as a biological process similar to bone formation involving osteogenic differentiation of vascular smooth muscle cells (VSMCs). Cell division cycle 42 (CDC42), a Rac1 family member GTPase, is essential for cartilage development during endochondral bone formation. However, whether CDC42 affects osteogenic differentiation of VSMCs and vascular calcification remains unknown. In the present study, we observed a significant increase in the expression of CDC42 both in rat VSMCs and in calcified arteries during vascular calcification. Alizarin red staining and calcium content assay revealed that adenovirus-mediated CDC42 overexpression led to an apparent VSMC calcification in the presence of calcifying medium, accompanied with up-regulation of bone-related molecules including RUNX2 and BMP2. By contrast, inhibition of CDC42 by ML141 significantly blocked calcification of VSMCs in vitro and aortic rings ex vivo. Moreover, ML141 markedly attenuated vascular calcification in rats with CKD. Furthermore, pharmacological inhibition of AKT signal was shown to block CDC42-induced VSMC calcification. These findings demonstrate for the first time that CDC42 contributes to vascular calcification through a mechanism involving AKT signalling; this uncovered a new function of CDC42 in regulating vascular calcification. This may provide a potential therapeutic target for the treatment of vascular calcification in the context of CKD. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Interactive and Multifactorial Mechanisms of Calcific Vascular and Valvular Disease

Calcific vascular and valvular disease (CVVD) is widespread and has major health consequences. Although coronary artery calcification has long been associated with hyperlipidemia and increased mortality, recent evidence suggests that its progression is increased in association with cholesterol-lowering HMG-CoA reductase inhibitors ('statins') and long-term, high-intensity exercise. A nationwide trial showed no cardiovascular benefit of vitamin D supplements. Controversy remains as to whether calcium deposits in plaque promote or prevent plaque rupture. CVVD appears to occur through mechanisms similar to those of intramembranous, endochondral, and osteophytic skeletal bone formation. New evidence implicates autotaxin, endothelial-mesenchymal transformation, and microRNA and long non-coding RNA (lncRNA) as novel regulatory factors. New therapeutic options are being developed.

Wnt1 inhibits vascular smooth muscle cell calcification by promoting ANKH expression

AIMS

Wnt signaling plays a critical role in vascular calcification (VC). Wnt factors induce different physiological and pathological effects on cardiovascular functions. Wnt1, a ligand of Wnt/β-catenin signaling, promotes pro-angiogenesis and reduces myocardial infarction. The role of Wnt1 on VC in chronic kidney disease (CKD) is not fully understood.

METHODS AND RESULTS

We used human vascular smooth muscle cells (VSMCs) and a rat model of chronic renal failure (CRF), and observed a native protective mechanism by which VC is reduced via the activation of Wnt1 and its transcriptional target ANKH inorganic pyrophosphate transport regulator (ANKH) gene. ANKH is an essential calcification inhibitor that effluxes inorganic pyrophosphate (PPi) from VSMCs to play an inhibitory role in VC. Vascular ANKH and plasma PPi were significantly downregulated in the rat model of CRF. The knockdown or inhibition of ANKH reversed the effect of Wnt1 on VC in VSMCs. Clinical analysis revealed low plasma levels of Wnt1 and PPi were associated with CKD in patients. Applying a Wnt/β-catenin signaling agonist can alleviate the progression of VC.

CONCLUSION

This work reveals the ANKH regulation of Wnt1 in VSMCs is essential for blocking VC. Our findings may contribute to the development of medications that target Wnt signaling and/or ANKH to inhibit VC.

Role of smooth muscle cells in vascular calcification: implications in atherosclerosis and arterial stiffness

Vascular calcification is associated with a significant increase in all-cause mortality and atherosclerotic plaque rupture. Calcification has been determined to be an active process driven in part by vascular smooth muscle cell (VSMC) transdifferentiation within the vascular wall. Historically, VSMC phenotype switching has been viewed as binary, with the cells able to adopt a physiological contractile phenotype or an alternate ‘synthetic’ phenotype in response to injury. More recent work, including lineage tracing has however revealed that VSMCs are able to adopt a number of phenotypes, including calcific (osteogenic, chondrocytic, and osteoclastic), adipogenic, and macrophagic phenotypes. Whilst the mechanisms that drive VSMC differentiation are still being elucidated it is becoming clear that medial calcification may differ in several ways from the intimal calcification seen in atherosclerotic lesions, including risk factors and specific drivers for VSMC phenotype changes and calcification. This article aims to compare and contrast the role of VSMCs in driving calcification in both atherosclerosis and in the vessel media focusing on the major drivers of calcification, including aging, uraemia, mechanical stress, oxidative stress, and inflammation. The review also discusses novel findings that have also brought attention to specific pro- and anti-calcifying proteins, extracellular vesicles, mitochondrial dysfunction, and a uraemic milieu as major determinants of vascular calcification.

Dkk (Dickkopf) Proteins

Clinical and preclinical studies over the past 3 decades have uncovered a multitude of signaling pathways involved in the initiation and progression of atherosclerosis. From these studies, signaling by proteins of the Wnt family has recently emerged as an important player in the development of atherosclerosis. Wnt signaling is characterized by a large number of ligands, receptors, and coreceptors and can be regulated at many different levels. Among Wnt modulators, the evolutionary conserved Dkk (Dickkopf) proteins, and especially Dkk-1, the founding member of the family, are the best characterized. The role of Dkks in the pathophysiology of the arterial wall is only partially understood, but their involvement in atherosclerosis is becoming increasingly evident. This review introduces recent key findings on Dkk proteins and their functions in atherosclerosis and discusses the potential importance of modulating Dkk signaling as part of a novel, improved strategy for preventing and treating atherosclerosis-related diseases.

Visual Overview—

An online visual overview is available for this article.

Sfrp5/Wnt Pathway: A Protective Regulatory System in Atherosclerotic Cardiovascular Disease

Adipose tissue stores energy and is the largest endocrine organ in the body, producing several adipokines. However, among these adipokines, few play a role in the positive metabolism that promotes good health. Secreted frizzled-related protein (Sfrp)-5, an antagonist that directly binds to Wnt, has attracted interest due to its favorable effects on atherosclerotic cardiovascular disease (ASCVD). This review focuses on Sfrp5 biology and the roles of the Sfrp5/Wnt system in ASCVD.

Glycemic variability is associated with vascular calcification by the markers of endoplasmic reticulum stress-related apoptosis, Wnt1, galectin-3 and BMP-2

BACKGROUND

The present study identified whether glycemic variability (GV) was associated with vascular calcification and explored the underlying mechanisms.

METHODS

Eighty-four consecutive type 2 diabetic patients with unstable angina (UA) were included from January 2018 to June 2018 to calculate calcification scores using computerized tomographic angiography (CTA), and the patients were divided into 2 groups: high calcification score group (HCS group) and low calcification score group (LCS group). Intergroup differences in GV were determined via comparisons of the standard deviation (SD) of blood glucose. Calcification staining, content measurement, apoptosis evaluation and Western blot analysis of endoplasmic reticulum (ER) stress-related apoptosis, Wnt1, galectin-3 and bone morphogenetic protein-2 (BMP-2) were compared in cell cultures from rat vascular smooth muscle cells in the different degrees of GV.

RESULTS

The SD increased significantly with the increases in calcification scores from human studies (HCS group 2.37 ± 0.82 vs. LCS group 1.87 ± 0.78, p = 0.007). Multivariate logistic regression analysis suggested that increased SD and serum creatinine were independent predictors of calcification. The high GV group had a higher apoptotic rate, higher calcification content and higher expressions of glucose-regulated protein, caspase-3, Wnt1, galectin-3 and BMP-2 markers compared to the low GV group in the in vitro studies (p < 0.001).

CONCLUSION

We report the novel finding that GV is associated with vascular calcification, and ER stress-related apoptosis, Wnt1, galectin-3 and BMP-2 may be involved in this regulation.

Clinical advantages and disadvantages of anabolic bone therapies targeting the WNT pathway

The WNT signalling pathway is a key regulator of bone metabolism, particularly bone formation, which has helped to define the role of osteocytes - the most abundant bone cells - as orchestrators of bone remodelling. Several molecules involved in the control of the WNT signalling pathway have been identified as potential targets for the development of bone-building therapeutics for patients with osteoporosis. Several of these molecules have been investigated in animal models, but only inhibitors of sclerostin (which is produced by osteocytes) have been investigated in phase III clinical studies. Here, we review the rationale for these developments and the specificity and potential off-target actions of WNT-based therapeutics. We also describe the available preclinical and clinical studies and discuss the benefits and risks of using sclerostin inhibitors for the management of patients with osteoporosis.

Cardiovascular consequences of KATP overactivity in Cantu syndrome

Cantu syndrome (CS) is characterized by multiple vascular and cardiac abnormalities including vascular dilation and tortuosity, systemic hypotension, and cardiomegaly. The disorder is caused by gain-of-function (GOF) mutations in genes encoding pore-forming (Kir6.1, KCNJ8) and accessory (SUR2, ABCC9) ATP-sensitive potassium (KATP) channel subunits. However, there is little understanding of the link between molecular dysfunction and the complex pathophysiology observed, and there is no known treatment, in large part due to the lack of appropriate preclinical disease models in which to test therapies. Notably, expression of Kir6.1 and SUR2 does not fully overlap, and the relative contribution of KATP GOF in various cardiovascular tissues remains to be elucidated. To investigate pathophysiologic mechanisms in CS we have used CRISPR/Cas9 engineering to introduce CS-associated SUR2[A478V] and Kir6.1[V65M] mutations to the equivalent endogenous loci in mice. Mirroring human CS, both of these animals exhibit low systemic blood pressure and dilated, compliant blood vessels, as well dramatic cardiac enlargement, the effects being more severe in V65M animals than in A478V animals. In both animals, whole-cell patch-clamp recordings reveal enhanced basal KATP conductance in vascular smooth muscle, explaining vasodilation and lower blood pressure, and demonstrating a cardinal role for smooth muscle KATP dysfunction in CS etiology. Echocardiography confirms in situ cardiac enlargement and increased cardiac output in both animals. Patch-clamp recordings reveal reduced ATP sensitivity of ventricular myocyte KATP channels in A478V, but normal ATP sensitivity in V65M, suggesting that cardiac remodeling occurs secondary to KATP overactivity outside of the heart. These SUR2[A478V] and Kir6.1[V65M] animals thus reiterate the key cardiovascular features seen in human CS. They establish the molecular basis of the pathophysiological consequences of reduced smooth muscle excitability resulting from SUR2/Kir6.1-dependent KATP GOF, and provide a validated animal model in which to examine potential therapeutic approaches to treating CS.