Cortistatin inhibits arterial calcification in rats via GSK3β/β-catenin and protein kinase C signalling but not c-Jun N-terminal kinase signalling

Reduced Plasma Cortistatin is Related to Clinical Parameters in Patients with Essential Hypertension

BACKGROUND

Cortistatin (CST), an endogenous bioactive polypeptide, has been acknowledged for its protective effect against several cardiovascular diseases, but its relationship with hypertension remains unclear. Therefore, we aimed to investigate changes in plasma CST in hypertensive patients and further analyze correlations with blood pressure, metabolic parameters and left ventricular structure and function.

METHODS

In this hospital-based study, basic information and plasma samples for evaluating clinically relevant indicators such as total cholesterol (TC), triglycerides (TGs), fasting blood glucose (FGB), serum creatinine (Scr) and CST were collected from 81 essential hypertension patients and 75 normotensive subjects. Plasma CST levels were examined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared with normotensive subjects, plasma CST was significantly lower in hypertensive patients. Plasma CST levels in hypertensive patients without blood pressure control was significantly lower than those of hypertensive patients with blood pressure control. Plasma CST levels were significantly negatively correlated with SBP and serum creatinine (Scr) in the overall population. Furthermore, multivariate logistic regression analysis showed that the OR of CST for hypertension was 0.64 using the unadjusted model, and there was still statistical significance using the four-adjusted model.

CONCLUSIONS

The circulating concentration of CST was significantly lower in hypertensive patients and was higher after blood pressure control, suggesting that CST may be a new endogenous protective target for hypertension.

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.

Nidogen-2 is a Novel Endogenous Ligand of LGR4 to Inhibit Vascular Calcification

BACKGROUND

Vascular calcification is closely related to the all-cause mortality of cardiovascular events. Basement membrane protein nidogen-2 is a key component of the vascular extracellular matrix microenvironment and we recently found it is pivotal for the maintenance of contractile phenotype in vascular smooth muscle cells (VSMCs). However, whether nidogen-2 is involved in VSMCs osteochondrogenic transition and vascular calcification remains unclear.

METHODS

VSMCs was treated with high-phosphate to study VSMC calcification in vitro. Three different mice models (5/6 nephrectomy-induced chronic renal failure, cholecalciferol-overload, and periadventitially administered with CaCl₂) were used to study vascular calcification in vivo. Membrane protein interactome, coimmunoprecipitation, flow cytometric binding assay, surface plasmon resonance, G protein signaling, VSMCs calcium assays were performed to clarify the phenotype and elucidate the molecular mechanisms.

RESULTS

Nidogen-2 protein levels were significantly reduced in calcified VSMCs and aortas from mice in different vascular calcification model. Nidogen-2 deficiency exacerbated high-phosphate-induced VSMC calcification, whereas the addition of purified nidogen-2 protein markedly alleviated VSMC calcification in vitro. Nidogen-2^-/- mice exhibited aggravated aorta calcification compared to wild-type (WT) mice in response to 5/6 nephrectomy, cholecalciferol-overload, and CaCl₂ administration. Further unbiased coimmunoprecipitation and interactome analysis of purified nidogen-2 and membrane protein in VSMCs revealed that nidogen-2 directly binds to LGR4 (leucine-rich repeat G-protein-coupled receptor 4) with K_D value 26.77 nM. LGR4 deficiency in VSMCs in vitro or in vivo abolished the protective effect of nidogen-2 on vascular calcification. Of interest, nidogen-2 biased activated LGR4-Gαq-PKCα (protein kinase Cα)-AMPKα1 (AMP-activated protein kinase α1) signaling to counteract VSMCs osteogenic transition and mineralization.

CONCLUSIONS

Nidogen-2 is a novel endogenous ligand of LGR4 that biased activated Gαq- PKCα-AMPKα1 signaling and inhibited vascular calcification.

Endogenous Vasoactive Peptides and Vascular Aging-Related Diseases

Vascular aging is a specific type of organic aging that plays a central role in the morbidity and mortality of cardiovascular and cerebrovascular diseases among the elderly. It is essential to develop novel interventions to prevent/delay age-related vascular pathologies by targeting fundamental cellular and molecular aging processes. Endogenous vasoactive peptides are compounds formed by a group of amino acids connected by peptide chains that exert regulatory roles in intercellular interactions involved in a variety of biological and pathological processes. Emerging evidence suggests that a variety of vasoactive peptides play important roles in the occurrence and development of vascular aging and related diseases such as atherosclerosis, hypertension, vascular calcification, abdominal aortic aneurysms, and stroke. This review will summarize the cumulative roles and mechanisms of several important endogenous vasoactive peptides in vascular aging and vascular aging-related diseases. In addition, we also aim to explore the promising diagnostic function as biomarkers and the potential therapeutic application of endogenous vasoactive peptides in vascular aging-related diseases.

MiR-140-5p upregulation suppressed β-glycerophosphate-induced vascular smooth muscle cell calcification via targeting TLR4

BACKGROUND

The role and function of microRNA (miRNA, miR)-140-5p in the calcification of vascular smooth muscle cells (VSMCs) have been explored in this study.

METHODS

The calcium nodules formed in transfected and β-glycerophosphate (β-GP)-treated VSMCs were observed using Alizarin Red S staining, and alkaline phosphatase (ALP) activity was determined. VSMC apoptosis was detected with flow cytometry assay. The target gene of miR-140-5p was predicted and confirmed with dual-luciferase reporter assay. Relative expressions of miR-140-5p, toll like receptor 4 (TLR4) and vascular calcification-related proteins (α-smooth muscle actin, α-SMA; Msh Homeobox 2, MSX2; bone morphogenetic protein 2, BMP2; Kruppel-like factor 4, KLF4; Runt-related transcription factor 2, RUNX2) were measured through quantitative real time polymerase chain reaction (qRT-PCR) and western blot.

RESULTS

MiR-140-5p upregulation reversed the effects of β-GP on downregulating miR-140-5p and α-SMA expressions, enhancing ALP activity, calcium nodule formation and cell apoptosis, and upregulating levels of MSX2, BMP2, KLF4 and RUNX2. TLR4 was the target of miR-140-5p, and offset the effects of miR-140-5p on β-GP-induced VSMCs.

CONCLUSIONS

MiR-140-5p upregulation represses β-GP-induced calcification of VSMCs via targeting TLR4, providing a potential therapeutic method for vascular calcification.

CORTISTATIN REGULATES FIBROSIS AND MYOFIBROBLAST ACTIVATION IN EXPERIMENTAL HEPATOTOXIC- AND CHOLESTATIC-INDUCED LIVER INJURY

BACKGROUND AND PURPOSE

Liver fibrosis induced by chronic hepatic injury remains as a major cause of morbidity and mortality worldwide. Identification of susceptibility/prognosis factors and new therapeutic tools for treating hepatic fibrotic disorders are urgent medical needs. Cortistatin is a neuropeptide with potent anti-inflammatory and anti-fibrotic activities in lung that binds to receptors that are expressed in liver fibroblasts and hepatic stellate cells. We evaluated the capacity of cortistatin to regulate liver fibrosis.

EXPERIMENTAL APPROACH

We experimentally induced liver fibrosis in mice by chronic CCl₄ exposition and bile duct ligation and evaluated the histopathological signs and fibrotic markers.

KEY RESULTS

Hepatic expression of cortistatin inversely correlated with liver fibrosis grade in mice and humans with hepatic disorders. Cortistatin-deficient mice showed exacerbated signs of liver damage and fibrosis and increased mortality rates when challenged to hepatotoxic and cholestatic injury. Compared to wild-type mice, non-parenchymal liver cells isolated from cortistatin-deficient mice showed increased presence of cells with activated myofibroblast phenotypes and a differential genetic signature that is indicative of activated hepatic stellate cells and periportal fibroblasts and of myofibroblasts with active contractile apparatus. Cortistatin treatment reversed in vivo and in vitro these exaggerated fibrogenic phenotypes and protected from progression to severe liver fibrosis in response to hepatic injury.

CONCLUSION AND IMPLICATIONS

We identify cortistatin as an endogenous molecular break of liver fibrosis and its deficiency as a potential poor-prognosis marker for chronic hepatic disorders that course with fibrosis. Cortistatin-based therapies emerge as attractive strategies for ameliorating severe hepatic fibrosis of various etiologies.

The ameliorative effect of terpinen-4-ol on ER stress-induced vascular calcification depends on SIRT1-mediated regulation of PERK acetylation

Endoplasmic reticulum (ER) stress-mediated phenotypic switching of vascular smooth muscle cells (VSMCs) is key to vascular calcification (VC) in patients with chronic kidney disease (CKD). Studies have shown that activation/upregulation of SIRT1 has a protective effect on CKD-VC. Meanwhile, although terpinen-4-ol has been shown to exert a protective effect against cardiovascular disease, its role and underlying mechanism in VC remain unclear. Herein, we explored whether terpinen-4-ol alleviates ER stress-mediated VC through sirtuin 1 (SIRT1) and elucidated its mechanism to provide evidence for its application in the clinical prevention and treatment of VC. To this end, a CKD-related VC animal model and β-glycerophosphate (β-GP)-induced VSMC calcification model were established to investigate the role of terpinen-4-ol in ER stress-induced VC, in vitro and in vivo. Additionally, to evaluate the involvement of SIRT1, mouse and VSMC Sirt1-knockdown models were established. Results show that terpinen-4-ol inhibits calcium deposition, phenotypic switching, and ER stress in VSMCs in vitro and in vivo. Furthermore, pre-incubation of VSMCs with terpinen-4-ol or a SIRT1 agonist, decreased β-GP-induced calcium salt deposition, increased SIRT1 protein level, and inhibited PERK-eIF2α-ATF4 pathway activation, thus, alleviating VC. Similar results were observed in VSMCs induced to overexpress SIRT1 via lentivirus transcription. Meanwhile, the opposite results were obtained in SIRT1-knockdown models. Further, results suggest that SIRT1 physically interacts with, and deacetylates PERK. Specifically, mass spectrometry analysis identified lysine K889 as the acetylation site of SIRT1, which regulates PERK. Finally, inhibition of SIRT1 reduced the effect of terpinen-4-ol on the deacetylation of PERK in vitro and in vivo and weakened the inhibitory effect of terpinen-4-ol against ER stress-mediated VC. Cumulatively, terpinen-4-ol was found to inhibit post-translational modification of PERK at the K889 acetylation site by upregulating SIRT1 expression, thereby ameliorating VC by regulating ER stress. This study provides insights into the underlying molecular mechanism of terpinen-4-ol, supporting its development as a promising therapeutic agent for CKD-VC.

Cardioprotection of cortistatin against isoproterenol-induced myocardial injury in rats

Background

The present study was designed to examine whether cortistatin (CORT) could protect rats from myocardial injury induced by subcutaneously injecting isoproterenol (ISO) and to clarify the possible mechanisms.

Methods

Male Sprague-Dawley (SD) rats were placed at random into four groups: the control group, the ISO group, the ISO + CORT 25 µg/(kg·d) group, and the ISO + CORT 50 µg/(kg·d) group. Rat models of myocardial injury were established with the subcutaneous (s.c.) injections of 85 mg/kg ISO for 2 days. In the ISO+ CORT 25 µg/(kg·d) group and ISO+ CORT 50 µg/(kg·d) group, rats were given s.c. injections of CORT 25 µg/(kg·d) and CORT 50 µg/(kg·d) on the day before ISO, 3 days, respectively. Serum malondialdehyde (MDA) content, lactate dehydrogenase (LDH) activity, and creatine kinase isoenzyme (CK-MB) activity were measured by corresponding test kits. Western blot was applied to evaluate the expression of endoplasmic reticulum stress-related protein glucose regulatory protein 78 (GRP78), enhancer-binding protein homologous protein (CHOP), cysteinyl aspartate specific proteinase-12 (caspase-12), LC3-II, Beclin-1, and p62 in the rat myocardium.

Results

CORT alleviated the increased enzyme activities of serum LDH and CK-MB, and content of MDA (a typical marker of lipid peroxidation) in rats induced by ISO. CORT also prevented pathological myocardial injury in rats induced by ISO. Moreover, CORT attenuated the increased protein levels of GRP78, CHOP, and caspase-12, and reduced the increase of LC3-II, LC3-II/I, Beclin-1, and p62 in rats induced by ISO.

Conclusions

These data demonstrate that CORT can attenuate ISO-induced acute myocardial injury in rats likely by reducing lipid peroxidation, and inhibiting endoplasmic reticulum stress and autophagy. This supports CORT as a potentially being a new target for preventing and treating myocardial injury and its related disease.

Osteogenic gene markers are epigenetically reprogrammed during contractile-to-calcifying vascular smooth muscle cell phenotype transition

The understanding of vascular calcification-based mechanism is an urgent pending task in vascular biology and this prompted us to better address this issue by investigating whether DNA methylation mechanism might drive osteogenic marker genes modulation in primary human vascular smooth muscle cells (VSMCs) responding to calcium and phosphate levels overload up to 72 h. Firstly, our data shows this calcifying process recapitulates the molecular repertory of osteogenic biomarkers and specifically requiring RUNX2, Osterix and ALP, BSP genes activations along 72 h in vitro, and this behavior was validated here using other lineages. Conversely, both BMPs 4 and 7 were significantly overexpressed, maybe already as a mechanism in response to RUNX2 and Osterix genes activities identified earlier in response to the calcifying condition, and taken into maintain the calcifying phenotype of VSMCs. Additionally, survival signaling was maintained active and accompanied by a dynamic cytoskeleton rearrangement signaling requiring MAPK and AKT phosphorylations. Moreover, during the contractile-to-calcifying transition phenotype of VSMCs, epigenetic machinery was finely modulated, requiring the translocation of DNMT3B and TET2 into nucleus and this prompted us evaluating whether the profile of osteogenic-related gene promoters' methylation might contribute with this process. By firstly estimating 5meC/5 hmeC ratio changes, we further specifically show the significance of the epigenetic modulation of Osterix and Bone sialoprotein related gene promoters, presenting a positive correlation between the epigenetic signature of their gene promoters and transcriptional patterns. Altogether, our results show for the first time the importance of epigenetic mechanism on modulating osteogenic gene markers reprogramming during calcifying VSMCs phenotype acquisition, which might drive the genesis of vascular ectopic calcification.

Salusin-β Promotes Vascular Calcification via Nicotinamide Adenine Dinucleotide Phosphate/Reactive Oxygen Species-Mediated Klotho Downregulation

Aims: Vascular calcification (VC) is a hallmark feature of cardiovascular disease and a significant risk factor for morbidity and mortality. Salusin-β exerts cardiovascular regulating effects in hypertension, atherosclerosis, and diabetes. The present study was designed to examine the roles of salusin-β in the progression of VC and its downstream signaling mechanisms. Results: Salusin-β expression in both the aortas of VC rats induced by vitamin D3 and nicotine and vascular smooth muscle cells (VSMCs) incubated with calcifying media was increased. Salusin-β knockdown remarkably reduced VC, whereas overexpression of salusin-β exacerbated VC both in vitro and in vivo. Overexpression of salusin-β promoted the VSMC osteochondrogenic transition, decreased Klotho protein levels, enhanced Ras-related C3 botulinum toxin substrate 1 (Rac1) activity and the translocation of p47phox to the membrane, increased the expression of nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase subunits and the production of reactive oxygen species (ROS) with or without calcifying media; however, salusin-β deficiency played the opposite roles. The calcification and downregulated Klotho protein levels induced by salusin-β were restored by ROS scavenger N-acetyl-l-cysteine, diphenyleneiodonium chloride [an inhibitor of flavin-containing enzyme, including NAD(P)H oxidase], or gene knockdown of NAD(P)H oxidase (NOX)-2, p22phox, or p47phox but were not affected by NOX-1 and NOX-4 knockdown. Klotho knockdown attenuated the protective effect of salusin-β deficiency on VSMC calcification. By contrast, exogenous Klotho ameliorated the development of VC and ROS generation induced by salusin-β overexpression. Innovation: Salusin-β is a critical modulator in VC. Conclusion: Salusin-β regulates VC through activation of NAD(P)H/ROS-mediated Klotho downregulation, suggesting that salusin-β may be a novel target for treatment of VC.

CXCL12 promotes atherosclerosis by downregulating ABCA1 expression via the CXCR4/GSK3β/β-cateninT120/TCF21 pathway

CXC chemokine ligand 12 (CXCL12) is a member of the CXC chemokine family and mainly acts on cell chemotaxis. CXCL12 also elicits a proatherogenic role, but the molecular mechanisms have not been fully defined yet. We aimed to reveal if and how CXCL12 promoted atherosclerosis via regulating lipid metabolism. In vitro, our data showed that CXCL12 could reduce ABCA1 expression, and it mediated cholesterol efflux from THP-1-derived macrophages to apoA-I. Data from the luciferase reporter gene and chromatin immunoprecipitation assays revealed that transcription factor 21 (TCF21) stimulated the transcription of ABCA1 via binding to its promoter region, which was repressed by CXCL12. We found that CXCL12 increased the levels of phosphorylated glycogen synthase kinase 3β (GSK3β) and the phosphorylation of β-catenin at the Thr120 position. Inactivation of GSK3β or β-catenin increased the expression of TCF21 and ABCA1. Further, knockdown or inhibition of CXC chemokine receptor 4 (CXCR4) blocked the effects of CXCL12 on TCF21 and ABCA1 expression and the phosphorylation of GSK3β and β-catenin. In vivo, the overexpression of CXCL12 in Apoe^-/- mice via lentivirus enlarged the atherosclerotic lesion area and increased macrophage infiltration in atherosclerotic plaques. We further found that the overexpression of CXCL12 reduced the efficiency of reverse cholesterol transport and plasma HDL-C levels, decreased ABCA1 expression in the aorta and mouse peritoneal macrophages (MPMs), and suppressed cholesterol efflux from MPMs to apoA-I in Apoe^-/- mice. Collectively, these findings suggest that CXCL12 interacts with CXCR4 and then activates the GSK-3β/β-catenin^T120/TCF21 signaling pathway to inhibit ABCA1-dependent cholesterol efflux from macrophages and aggravate atherosclerosis. Targeting CXCL12 may be a novel and promising strategy for the prevention and treatment of atherosclerotic cardiovascular diseases.

Cortistatin exerts antiproliferation and antimigration effects in vascular smooth muscle cells stimulated by Ang II through suppressing ERK1/2, p38 MAPK, JNK and ERK5 signaling pathways

Background

Vascular remodeling, that contributes to cardiovascular diseases such as hypertension develops by anomalous proliferation and migration of vascular smooth muscle cells (VSMCs). Cortistatin (CST), a newly discovered biological peptide, has been acknowledged for its protective effects against cardiovascular diseases. Whether CST has an inhibitory regulation role in angiotensin II (Ang II)-induced proliferation and migration of VSMCs and what molecular mechanisms may participate in the CST inhibition process are still unknown.

Methods

VSMCs were divided into control group, Ang II (10^-7 M) group, Ang II + PD98059 (5×10^-5 M) group, Ang II + SB203580 (10^-5 M) group, Ang II + SP600125 (10^-5 M) group, Ang II + XMD17-109 (10^-6 M) group, Ang II + CST (10^-8 M) group and Ang II + CST (10^-7 M) group. Cell proliferation was detected by western blotting and cell counting kit-8 (CCK8) analysis. Migration of VSMCs was measured by Transwell assay.

Results

Compared with control group, Ang II upregulated the expression levels of proliferating cell nuclear antigen (PCNA) and osteopontin (OPN) and downregulated that of α-smooth muscle actin (α-SMA), increased the proliferation rate as shown by CCK8 and VSMC migration as shown by Transwell assay in cultured VSMCs of the Ang II group. Meanwhile, in Ang II-cultured VSMCs, we found activation of extracellular signal-regulated kinase (ERK) 1/2, p38 MAP kinase (p38 MAPK), c-Jun N-terminal kinase (JNK), and ERK5 pathways by western blotting at different time points. However, the proliferation and migration stimulated by Ang II were partly reversed by drug inhibitors of the four pathways, namely, PD98059, SB203580, SP600125 and XMD17-109. When Ang II-stimulated VSMCs were cultured with CST pretreatment, we found that proliferation and migration were greatly suppressed as well as that the ERK1/2, p38 MAPK, JNK and ERK5 pathways were deactivated by CST.

Conclusions

The accumulated data suggest that CST may play a protective role in Ang II-promoted proliferation and migration of VSMCs via inhibiting the mitogen-activated protein kinase (MAPK) family pathways, providing a new orientation of CST in protecting against cardiovascular diseases.

Cortistatin, a novel cardiovascular protective peptide

Cortistatin (CST) is a small molecule bioactive peptide containing an FWKT tetramer. It is widely distributed in nervous, immune and endocrine systems. Many studies have shown that CST can exert many biological effects, for example: regulating sleep, learning and memory processes, inducing immune tolerance, inhibiting inflammatory responses, and regulating endocrine metabolism. Notably, it is found that CST and its receptors are also widely distributed in the cardiovascular system, such as the aorta, coronary arteries and heart. In recent years, increasing studies have shown that CST played an important role in the development of cardiovascular diseases, such as reducing myocardial damage, inhibiting autoimmune myocarditis, alleviating vascular smooth muscle cell (VSMC) proliferation and migration, reducing vascular calcification (VC), and inhibiting atherosclerosis and aneurysm formation. Therefore, we reviewed the cardiovascular effects of CST in the heart and blood vessels, which will help to understand the role of CST and its receptors in the pathogenesis of cardiovascular diseases, and highlight novel strategies and targets for the prevention and treatment of cardiovascular diseases.

Silencing GSK3β instead of DKK1 can inhibit osteogenic differentiation caused by co-exposure to fluoride and arsenic

Chronic exposure to combined fluoride (F) and arsenic (As) continues to be a major public health problem worldwide, attracting the attention of an increasing number of researchers. While bone is the main target organ of syndrome of endemic arsenic poisoning and fluorosis (SEAF), the specific mechanism and targeted intervention remains uncertain. The first question in this study sought to determine the interaction of F and As on the Wnt signaling pathway and its role in osteogenic differentiation in the SEAF population. As can be seen from the data, with the increase in exposure to F, the content of Wnt signaling inhibitor Dickkopf-related protein 1 (DKK1) gradually decreased, but the expression of glycogen synthase kinase-3β (GSK3β), β-catenin and the osteogenic differentiation indicators pro-collagen I alpha 1 (COL1A1) and bone alkaline phosphatase (BALP) were increased. Next, we grouped the SEAF population according to urinary As and found that As can upregulate the GSK3β, β-catenin level and the bone formation bio-marker BALP in serum. But the experiments did not detect any evidence that As can change the content of DKK1 in serum. To better understand the combined effects of F and As on the Wnt signaling pathway, we performed further interaction analysis. These results suggest that the interaction of F and As can inhibit the GSK3β, β-catenin, COL1A1 and BALP. And DKK1 is mainly manifested by the independent effect of F. To further study the role of DKK1 and GSK3β in fluoride-arsenic pollution combined with osteogenic differentiation, we attempted to silence the DKK1 and GSK3β gene in hFOB 1.19 cells. The results show that F, As alone and in combination exposure can up-regulate GSK catenin transcription and protein expression levels and down-regulate DKK1, and COL1A1 and ALP are significantly increased, after silenced the DKK1. The same results did not appear after silenced the GSK3β. F and As alone and in combination exposure did not reverse the inhibition of GSK3β and β-catenin by GSK3β silencing, and COL1A1 and ALP are significantly decreased. The results indicate that silencing GSK3β instead of DKK1 can inhibit osteogenic differentiation caused by co-exposure to fluoride and arsenic. This study can provide a scientific basis for further understanding the causes of bone formation caused by F and As and the improvement of targeted intervention strategies.

Death-associated protein kinase 3 deficiency alleviates vascular calcification via AMPK-mediated inhibition of endoplasmic reticulum stress

Vascular calcification (VC) is a critical feature of chronic kidney disease (CKD), diabetes, hypertension, and atherosclerosis. Death-associated protein kinase 3 (DAPK3) is involved in vascular remodeling in hypertension. However, it remains to be clarified whether DAPK3 controls vascular smooth muscle cell (VSMC) phenotypic transition into an osteogenic cell phenotype, which is an important process for VC. In vivo VC was induced in rats by vitamin D3 and nicotine. VSMCs were incubated with calcifying media containing β-glycerophosphate and Ca²⁺ to induce VC in vitro. Herein, we demonstrated increased expression of DAPK3 in the aortas of VC rats and VSMCs cultured in calcifying media. Knockdown of DAPK3 significantly inhibited calcifying media-induced VSMC mineralization and retarded the phenotypic transformation of VSMCs into osteogenic cells. Silencing of DAPK3 suppressed endoplasmic reticulum stress (ERS) related protein expressions, but upregulated the phosphorylation level of AMP-activated protein kinase (AMPK) in calcified VSMCs. Moreover, pretreatment with AMPK inhibitor Compound C abolished DAPK3 shRNA-mediated inhibition of ERS in VSMCs. In vivo, DAPK inhibitor significantly prevented calcium deposition in the aortas of VC rats. The present results revealed that DAPK3 modulated VSMC calcification through AMPK-mediated ERS signaling.

Cortistatin binds to TNF-α receptors and protects against osteoarthritis

Background

Osteoarthritis (OA) is a common degenerative disease, and tumor necrosis factor (TNF-α) is known to play a critical role in OA. Cortistatin (CST) is a neuropeptide discovered over 20  years ago, which plays a vital role in inflammatory reactions. However, it is unknown whether CST is involved in cartilage degeneration and OA development.

Methods

The interaction between CST and TNF-α receptors was investigated through Coimmunoprecipitation and Biotin-based solid-phase binding assay. Western blot, Real-time PCR, ELISA, immunofluorescence staining, nitrite production assay and DMMB assay of GAG were performed for the primary chondrocyte experiments. Surgically induced and spontaneous OA models were established and western blot, flow cytometry, Real-time PCR, ELISA, immunohistochemistry and fluorescence in vivo imaging were performed for in vivo experiments.

Findings

CST competitively bound to TNFR1 as well as TNFR2. CST suppressed proinflammatory function of TNF-α. Both spontaneous and surgically induced OA models indicated that deficiency of CST led to an accelerated OA-like phenotype, while exogenous CST attenuated OA development in vivo. Additionally, TNFR1- and TNFR2-knockout mice were used for analysis and indicated that TNFRs might be involved in the protective role of CST in OA. CST inhibited activation of the NF-κB signaling pathway in OA.

Interpretation

This study provides new insight into the pathogenesis and therapeutic strategy of cartilage degenerative diseases, including OA.

Fund

The National Natural Science Foundation of China, the Natural Science Foundation of Shandong Province, Key Research and Development Projects of Shandong Province and the Cross-disciplinary Fund of Shandong University.

Role of PKB/SGK-dependent phosphorylation of GSK-3α/β in vascular calcification during cholecalciferol overload in mice

Medial vascular calcification is a highly regulated process involving osteo-/chondrogenic transdifferentiation of vascular smooth muscle cells. Both, protein kinase B (PKB) and serum- and glucocorticoid-inducible kinase 1 (SGK1) are involved in the intracellular signaling of vascular calcification and both phosphorylate and inactivate glycogen synthase kinase 3 (GSK-3). The present study explored whether PKB/SGK-dependent phosphorylation of GSK-3α/β is involved in vascular calcification. Experiments were performed in Gsk-3α/β double knockin mice lacking functional PKB/SGK phosphorylation sites (gsk-3^KI) and corresponding wild-type mice (gsk-3^WT) following high-dosed cholecalciferol treatment as well as ex vivo in aortic ring explants from gsk-3^KI and gsk-3^WT mice treated without and with phosphate. In gsk-3^WT mice, high-dosed cholecalciferol induced vascular calcification and aortic osteo-/chondrogenic signaling, shown by increased expression of osteogenic markers Msx2, Cbfa1 and tissue-nonspecific alkaline phosphatase (Alpl). All these effects were suppressed in aortic tissue from gsk-3^KI mice. Cholecalciferol decreased aortic Gsk-3α/β phosphorylation (Ser^21/9) in gsk-3^WT mice, while no phosphorylation was observed in gsk-3^KI mice. Moreover, the mRNA expression of type III sodium-dependent phosphate transporter (Pit1) and plasminogen activator inhibitor 1 (Pai1) was increased following cholecalciferol treatment in aortic tissue of gsk-3^WT mice, effects again blunted in gsk-3^KI mice. In addition, phosphate treatment induced mineral deposition and osteogenic markers expression in aortic ring explants from gsk-3^WT mice, effects reduced in aortic ring explants from gsk-3^KI mice. In conclusion, vascular PKB/SGK-dependent phosphorylation of GSK-3α/β contributes to the osteoinductive signaling leading to vascular calcification.