Deficiency of peroxisome proliferator-activated receptor α attenuates apoptosis and promotes migration of vascular smooth muscle cells

Peroxisome proliferator-activated receptor (PPAR) α is widely expressed in the vasculature and has pleiotropic and lipid-lowering independent effects, but its role in the growth and function of vascular smooth muscle cells (VSMCs) during vascular pathophysiology is still unclear. Herein, VSMC-specific PPARα-deficient mice (Ppara ^ΔSMC) were generated by Cre-LoxP site-specific recombinase technology and VSMCs were isolated from mice aorta. PPARα deficiency attenuated VSMC apoptosis induced by angiotensin (Ang) II and hydrogen peroxide, and increased the migration of Ang II-challenged cells.

Promyelocytic leukemia protein: an atherosclerosis suppressor protein?

As many as 70% of cells in atherosclerotic plaque are vascular smooth muscle cell (VSMC) in origin, and pathways and proteins which regulate VSMC migration, proliferation, and phenotype modulation represent novel targets for rational drug design to reduce atherosclerotic vascular disease. In this volume of Clinical Science, Karle et al. demonstrate that tumor suppressor, promyelocytic leukemia protein (PML) plays an important role in regulation of VSMC phenotype and response to inflammatory stimuli (Clin Sci (2021) 135(7), 887-905; DOI: 10.1042/CS20201399). This important work demonstrates that PML, previously unrecognized as a participant in development of atherosclerosis, may represent a novel target for anti-atherosclerotic therapeutic modalities.

Research advance of Nrf2 on atherosclerosis by regulating vascular smooth muscle cell

Atherosclerosis is a common pathological change in cardiovascular disease. Vascular smooth muscle cell is the main source of plaque cell and extracellular matrix, and nuclear factor-erythroid 2-related factor 2 (Nrf2) is a key transcription factor regulating the function of vascular smooth muscle cell. In the process of atherosclerosis, Nrf2 signaling pathway has the following regulatory effects on vascular smooth muscle cell: regulating the phenotype of vascular smooth muscle cell to change to the direction conducive to the alleviation of disease progression; inhibiting the proliferation and migration of vascular smooth muscle cell; mitigating the level of blood lipid; alleviating vascular smooth muscle cell calcification, aging and apoptosis process. This article reviews the specific mechanisms of Nrf2 regulating atherosclerosis, such as phenotypic transformation, proliferation and migration, lipid metabolism, calcification, aging and apoptosis in atherosclerosis, in order to provide a basis for understanding the molecular mechanism of atherosclerosis development and finding therapeutic targets.

Atypical antipsychotic olanzapine inhibits voltage-dependent K+ channels in coronary arterial smooth muscle cells

BACKGROUND

Olanzapine, an FDA-approved atypical antipsychotic, is widely used to treat schizophrenia and bipolar disorder. In this study, the inhibitory effect of olanzapine on voltage-dependent K⁺ (Kv) channels in rabbit coronary arterial smooth muscle cells was investigated.

METHODS

Electrophysiological recordings were performed in freshly isolated coronary arterial smooth muscle cells.

RESULTS

Olanzapine inhibited the Kv channels in a concentration-dependent manner with an IC₅₀ value of 7.76 ± 1.80 µM and a Hill coefficient of 0.82 ± 0.09. Although olanzapine did not change the steady-state activation curve, it shifted the inactivation curve to a more negative potential, suggesting that it inhibited Kv currents by affecting the voltage sensor of the Kv channel. Application of 1 or 2 Hz train pulses did not affect the olanzapine-induced inhibition of Kv channels, suggesting that its effect on Kv channels occurs in a use (state)-independent manner. Pretreatment with DPO-1 (Kv1.5 subtype inhibitor) reduced the olanzapine-induced inhibition of Kv currents. In addition, pretreatment with guangxitoxin (Kv2.1 subtype inhibitor) and linopirdine (Kv7 subtype inhibitor) partially decreased the degree of Kv current inhibition. Olanzapine induced membrane depolarization.

CONCLUSION

From these results, we suggest that olanzapine inhibits the Kv channels in a concentration-dependent, but state-independent, manner by affecting the gating properties of Kv channels. The primary Kv channel target of olanzapine is the Kv1.5 subtype.

Circadian misalignment promotes vascular smooth muscle cell apoptosis via defective autophagy

Defective autophagy in vascular smooth muscle cells (VSMCs) in response to oxidative stress can lead to cellular apoptosis and plaque instability. Previous studies have revealed that the circadian clock system is involved in autophagic regulation and plaque progression. However, the mechanism by which circadian rhythmicity influences VSMC autophagy and plaque stability remains unclear. Our study described the circadian profiles in atheromatous plaques and verified the role of circadian misalignment in VSMC autophagy and apoptosis. We found that the mRNA expression levels of circadian locomotor output cycles protein kaput (CLOCK) and Beclin 1 were significantly decreased in unstable plaques compared with stable plaques. No significant differences were observed in other circadian rhythm genes. VSMCs treated with oxidized low-density lipoprotein (ox-LDL, 80 μg/ml) exhibited abnormal circadian rhythmicity and impaired autophagy, as evidenced by consistent decreases in CLOCK and Beclin 1 expression, suggesting a correlation between CLOCK and autophagy. CLOCK protein expression was inhibited by ox-LDL, accompanied by defective autophagy and an increased apoptosis rates (P < 0.05). Administration of rapamycin (10 nM) reversed the effect of ox-LDL on VSMC autophagy and apoptosis. Finally, CLOCK silencing led to a considerable decrease in autophagy. VSMCs with stable CLOCK silencing also showed an increased apoptosis rate. In addition, gene silencing of CLOCK in VSMCs counteracted the effects of moderate rapamycin concentrations on autophagy and apoptosis. In conclusion, these findings suggested that the CLOCK-dependent rapamycin signaling pathway is a critical mediator in ox-LDL-induced VSMCs with defective autophagy that exacerbates plaque destabilization.

miR-34c inhibits PDGF-BB-induced HAVSMCs phenotypic transformation and proliferation via PDGFR-β/SIRT1 pathway

The purpose of this study was to explore the effect of miR-34c on PDGF-BB-induced HAVSMCs phenotypic transformation and proliferation via PDGFR-β/SIRT1 pathway, so as to find a new method for early diagnosis and treatment of cardiovascular disease. HA-VSMCs were treated with platelet-derived growth factor-BB (PDGF-BB) at 0 h, 12 h, 24 h, 48 h or 36 h to explore the optimal time for phenotypic transformation of VSMCs. And then, PDGF-BB-induced HA-VSMCs were transfected with miR-34c mimics/mimics NC and pcDNA3.1-PDGFR-β/pcDNA3.1-NC to observe cell biological behaviour. CCK8 was used to detect cell proliferation activity. Transwell chamber assay was used to detect cell invasion. Early apoptosis was analyzed by flow cytometry. The expression of α-SMA and Smemb was detected by immunofluorescence staining. The expressions of PDGFR-β, IRF9, Acetyl-NF-κB/p65, Acetyl-p53 and CyclinD1 were analyzed by Western blot analysis. The expression of miR-34a, miR-34b and miR-34c was detected by RT-PCR, and the targeting relationship between miR-34c and PDGFR-β was detected by luciferase reporting assay. The results indicated the proliferation and migration of PDGF-BB-induced HA-VSMCs significantly increased, and apoptosis significantly decreased. Besides, α-SMA decreased significantly, while Smemb increased significantly. Furthermore, expressions of PDGFR-β, IRF9, Acetyl-NF-κB/p65, Acetyl-p53 and CyclinD1 increased significantly, and SIRT1 decreased significantly. Experimental results showed that, miR-34c mimics significantly inhibited cell proliferation and migration, and promoted cell apoptosis, and miR-34c inhibitor had the opposite effects. MiR-34c mimics significantly increased α-SMA expression and decreased Smemb expression, while the opposite effects were reflected after transfection with miR-34c inhibitor. Moreover, miR-34c mimics significantly decreased the expressions of PDGFR-β, IRF9, Acetyl-NF-κB/p65, Acetyl-p53 and CyclinD1, and significantly increased the expression of SIRT1, while miR-34c inhibitor had the opposite effects. Luciferase assay confirmed that PDGFR-β was a potential target of miR-34c. Subsequently, PDGF-BB-induced HA-VSMCs were co-transfected with miR-34c mimics and pcDNA3.1-PDGFR-β. The results indicated that PDGFR-β reversed the biological function of miR-34c mimic. The results revealed the potential application value of miR-34c as a marker molecule of phenotypic transformation, providing a potential target for improving phenotypic transformation.

The p53 pathway in vasculature revisited: A therapeutic target for pathological vascular remodeling?

Pathological vascular remodeling contributes to the development of restenosis following intraluminal interventions, transplant vasculopathy, and pulmonary arterial hypertension. Activation of the tumor suppressor p53 may counteract vascular remodeling by inhibiting aberrant proliferation of vascular smooth muscle cells and repressing vascular inflammation. In particular, the development of different lines of small-molecule p53 activators ignites the hope of treating remodeling-associated vascular diseases by targeting p53 pharmacologically. In this review, we discuss the relationships between p53 and pathological vascular remodeling, and summarize current experimental data suggesting that drugging the p53 pathway may represent a novel strategy to prevent the development of vascular remodeling.

SMYD3-PARP16 axis accelerates unfolded protein response and mediates neointima formation

Neointimal hyperplasia after vascular injury is a representative complication of restenosis. Endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) is involved in the pathogenesis of vascular intimal hyperplasia. PARP16, a member of the poly(ADP-ribose) polymerases family, is correlated with the nuclear envelope and the ER. Here, we found that PERK and IRE1α are ADP-ribosylated by PARP16, and this might promote proliferation and migration of smooth muscle cells (SMCs) during the platelet-derived growth factor (PDGF)-BB stimulating. Using chromatin immunoprecipitation coupled with deep sequencing (ChIP-seq) analysis, PARP16 was identified as a novel target gene for histone H3 lysine 4 (H3K4) methyltransferase SMYD3, and SMYD3 could bind to the promoter of Parp16 and increased H3K4me3 level to activate its host gene's transcription, which causes UPR activation and SMC proliferation. Moreover, knockdown either of PARP16 or SMYD3 impeded the ER stress and SMC proliferation. On the contrary, overexpression of PARP16 induced ER stress and SMC proliferation and migration. In vivo depletion of PARP16 attenuated injury-induced neointimal hyperplasia by mediating UPR activation and neointimal SMC proliferation. This study identified SMYD3-PARP16 is a novel signal axis in regulating UPR and neointimal hyperplasia, and targeting this axis has implications in preventing neointimal hyperplasia related diseases.

Resistin-like molecule beta augments phenotypic modulation of human aortic smooth muscle cell triggered by high glucose

Vascular muscle cells (VSMCs) participate in the pathophysiology of atherosclerosis. Resistin-like molecule beta (Relmβ) contributes to atherosclerosis development by activating macrophage. This study aims to investigate whether Relmβ regulates VSMC phenotypic modulation under high glucose environment. Human aortic vascular smooth muscle cells were cultured and treated with Relmβ in the presence or absence of high glucose. VSMC phenotypic modulation was assessed by expression of related markers. The migration of VSMCs was detected by wound healing assay and transwell assay. The proliferation of VSMCs was measured using CCK-8 assay. In this study, we observed that Relmβ modulated VSMC phenotypic modulation by down-regulating expression of smooth muscle α-actin (α-SMA), smooth muscle myosin heavy chain (SM-MHC), and calponin while up-regulating expression of osteopontin (OPN). Relmβ increased the expression of inflammatory genes in VSMCs. Relmβ also augmented VSMCs migration as well as proliferation. It is worth noting that all the effects of VSMCs were enhanced upon high glucose stimulation. The phosphorylation levels of p38MAPK and ERK1/2 were increased by co-treatment with Relmβ and high glucose. The p38 MAPK pathway inhibitor RWJ64809 and pERK1/2 inhibitor PD98059 significantly inhibited the proliferation of VSMCs induced by Relmβ and high glucose. Our results provide evidence that Relmβ augments phenotypic modulation and migration of human aortic smooth muscle cell induced by high glucose. Relmβ might be a potential target for treatment of atherosclerosis induced by hyperglycemia.

Single-cell RNA sequencing reveals the cellular heterogeneity of aneurysmal infrarenal abdominal aorta

AIMS

The artery contains numerous cell types which contribute to multiple vascular diseases. However, the heterogeneity and cellular responses of these vascular cells during abdominal aortic aneurysm (AAA) progression have not been well characterized.

METHODS AND RESULTS

Single-cell RNA sequencing was performed on the infrarenal abdominal aortas (IAAs) from C57BL/6J mice at Days 7 and 14 post-sham or peri-adventitial elastase-induced AAA. Unbiased clustering analysis of the transcriptional profiles from >4500 aortic cells identified 17 clusters representing nine-cell lineages, encompassing vascular smooth muscle cells (VSMCs), fibroblasts, endothelial cells, immune cells (macrophages, T cells, B cells, and dendritic cells), and two types of rare cells, including neural cells and erythrocyte cells. Seurat clustering analysis identified four smooth muscle cell (SMC) subpopulations and five monocyte/macrophage subpopulations, with distinct transcriptional profiles. During AAA progression, three major SMC subpopulations were proportionally decreased, whereas the small subpopulation was increased, accompanied with down-regulation of SMC contractile markers and up-regulation of pro-inflammatory genes. Another AAA-associated cellular response is immune cell expansion, particularly monocytes/macrophages. Elastase exposure induced significant expansion and activation of aortic resident macrophages, blood-derived monocytes and inflammatory macrophages. We also identified increased blood-derived reparative macrophages expressing anti-inflammatory cytokines suggesting that resolution of inflammation and vascular repair also persist during AAA progression.

CONCLUSION

Our data identify AAA disease-relevant transcriptional signatures of vascular cells in the IAA. Furthermore, we characterize the heterogeneity and cellular responses of VSMCs and monocytes/macrophages during AAA progression, which provide insights into their function and the regulation of AAA onset and progression.

MiR-506-3p Promotes the Proliferation and Migration of Vascular Smooth Muscle Cells via Targeting KLF4

BACKGROUND

The dysregulation of proliferation and migration of vascular smooth muscle cells (VSMCs) is one of the major causes of atherosclerosis (AS). Accumulating studies confirm that Kruppel-like factor 4 (KLF4) can regulate the proliferation and differentiation of VSMCs through multiple signaling pathways. However, the mechanism of KLF4 dysregulation remains unknown.

METHODS

Apolipoprotein E-knockout (ApoE-/-) mice and human VSMCs were used to establish AS animal model and cell model, respectively. qRT-PCR was employed to determine the expressions of miR-506-3p and KLF4. Cell Counting Kit -8, Transwell, TUNEL assays, and flow cytometry were performed to measure the proliferation, migration, and apoptosis of VSMCs. The upstream miRNAs of KLF4 were predicted by microT, miRanda, miRmap, and TargetScan databases. The interaction between KLF4 and miR-506-3p was confirmed using qRT-PCR, Western blot, and luciferase reporter gene assay.

RESULTS

KLF4 expression was significantly decreased in the VSMCs of ApoE-/- mice fed with high-fat diet and in human VSMCs treated with oxidized low-density lipoprotein in time-dependent and dose-dependent manners. The transfection of miR-506-3p mimics or KLF4 shRNA promoted the proliferation and migration of VSMCs but inhibited the apoptosis while miR-506-3p inhibitors and pcDNA3.1-KLF4 exerted opposite effects. Additionally, KLF4 was confirmed as a target gene of miR-506-3p and could be negatively regulated by miR-506-3p.

CONCLUSION

MiR-506-3p can promote the proliferation and migration of VSMCs via targeting KLF4, which can probably contribute to the pathogenesis of AS.

Extracellular vesicle-mediated miR135a-5p transfer in hypertensive rat contributes to vascular smooth muscle cell proliferation via targeting FNDC5

Background Extracellular vesicles (EVs) from vascular adventitial fibroblasts (AFs) contribute to the proliferation of vascular smooth muscle cells (VSMCs) and vascular remodeling in spontaneously hypertensive rat (SHR). This study shows the crucial roles of EVs-mediated miR135a-5p transfer in VSMC proliferation and the underlying mechanisms in hypertension. Methods AFs and VSMCs were obtained from the aorta of Wistar-Kyoto rat (WKY) and SHR. EVs were isolated from the culture of AFs with ultracentrifugation method. Results MiR135a-5p level in SHR-EVs was significantly increased. MiR135a-5p inhibitor prevented the SHR-EVs-induced VSMC proliferation. Fibronectin type III domain containing 5 (FNDC5) was a target gene of miR135a-5p. FNDC5 level was lower in VSMCs of SHR. MiR135a-5p inhibitor not only increased FNDC5 expression, but reversed the SHR-EVs-induced FNDC5 downregulation in VSMCs of SHR. MiR135a-5p mimic inhibited FNDC5 expression, but failed to promote the SHR-EVs-induced FNDC5 downregulation in VSMCs of SHR. Exogenous FNDC5 prevented the SHR-EVs-induced VSMC proliferation of both WKY and SHR. Knockdown of miR135a-5p in fibroblasts completely prevented the upregulation of miR135a-5p in the EVs. The SHR-EVs from the miR135a-5p knockdown-treated fibroblasts lost their roles in inhibiting FNDC5 expression and promoting proliferation in VSMCs of both WKY and SHR. Conclusions Increased miR135a-5p in the SHR-EVs promoted VSMC proliferation of WKY and SHR via inhibiting FNDC5 expression. MiR135a-5p and FNDC5 are crucial targets for intervention of VSMC proliferation in hypertension.

Apolipoprotein-AI and AIBP synergetic anti-inflammation as vascular diseases therapy: the new perspective

Vascular diseases (VDs) including pulmonary arterial hypertension (PAH), atherosclerosis (AS) and coronary arterial diseases (CADs) contribute to the higher morbidity and mortality worldwide. Apolipoprotein A-I (Apo A-I) binding protein (AIBP) and Apo-AI negatively correlate with VDs. However, the mechanism by which AIBP and apo-AI regulate VDs still remains unexplained. Here, we provide an overview of the role of AIBP and apo-AI regulation of vascular diseases molecular mechanisms such as vascular energy homeostasis imbalance, oxidative and endoplasmic reticulum stress and inflammation in VDs. In addition, the role of AIBP and apo-AI in endothelial cells (ECs), vascular smooth muscle (VSMCs) and immune cells activation in the pathogenesis of VDs are explained. The in-depth understanding of AIBP and apo-AI function in the vascular system may lead to the discovery of VDs therapy.

Lithium chloride represses abdominal aortic aneurysm via regulating GSK3β/SIRT1/NF-κB signaling pathway

Lithium chloride (LiCl), a pharmacological compound, was effective in reducing inflammation, but whether it can protect against abdominal aortic aneurysm (AAA) is largely unknown. This study is designed to investigate therapeutic effects of LiCl on AAA and the potential mechanism. Rat AAA models were induced by periaortic application of CaCl₂. AAA rats were treated by daily intraperitoneal injection of LiCl or vehicle alone to study the protection effects of LiCl in vivo. Rat primary vascular smooth muscle cells (VSMCs) stimulated with tumor necrosis factor (TNF)-α served as an in vitro model. LiCl treatment prevented the development of AAA through inhibiting the inflammatory cells infiltration and inflammatory cytokines overproduction, as well as attenuating superoxide production and elastin degradation in aorta of AAA rats. Additionally, the downregulation of p-GSK3β(Ser9) and SIRT1, upregulation of NF-κB(p-65), MMP-2 and MMP-9 in AAA were abolished by LiCl treatment. In vitro by upregulating p-GSK3β(Ser9), LiCl significantly induced SIRT1 expression, along with inhibition of the NF-κB activation and decreased elastin level elicited in VSMCs by TNF-α stimulation. SIRT1 activator SRT1720 achieved similar repressive effects as LiCl on TNF-α-induced NF-κB activation and decreased elastin in VSMCs. Moreover, administration of LiCl also caused regression of established rats AAA. This study provided the first evidence that LiCl prevented the development of AAA through inhibiting inflammation, MMPs, and superoxide production, and facilitating the biosynthesis of elastin. The beneficial effect of LiCl may be mediated by regulation GSK3β/SIRT1/NF-κB cascade.

VCAM-1-targeted and PPARδ-agonist-loaded nanomicelles enhanced suppressing effects on apoptosis and migration of oxidized low-density lipoprotein-induced vascular smooth muscle cells

Purpose: Nanomicelles (NMs) have been widely used for various biomedical applications due to its unique physiochemical properties. The present study aims to investigate the effects of vascular cell adhesion molecule-1 (VCAM-1)-targeted and peroxisome proliferator-activated receptor δ (PPARδ) agonist (GW0742)-loaded NMs on apoptosis and migration in oxidized low-density lipoprotein (ox-LDL)-induced human aortic vascular smooth muscle cells (HAVSMCs).

Methods: The GW0742-loaded NMs (M-GW) and VCAM-1-targeted NMs loaded with GW0742 (TM-GW) were prepared, and then the morphologies and the size distribution of M-GM and TM-GM were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. In vitro drug release assay of M-GM and TM-GM were performed as well. Next, HAVSMCs were cultured in medium containing ox-LDL to mimic atherosclerotic environment, and the effects of free GW0742, M-GM and TM-GM on endocytosis, cell migration and apoptosis, as well as the expression of VCAM-1, and proteins associated with migration and apoptosis were measured in HAVSMCs treated with ox-LDL.

Results: M-GM and TM-GM were successfully prepared. VCAM-1 was overexpressed in HAVSMCs treated with ox-LDL, and TM-GM had a strong targeting ability to HAVSMCs treated with ox-LDL compared with M-GM. In addition, compared with free GW0742, both M-GM and TM-GM significantly diminished cell apoptosis and migration in HAVSMCs treated with ox-LDL.

Conclusions: TM-GM had a superior suppressing effect on apoptosis and migration of ox-LDL-induced HAVSMCs.

MicroRNA-194 acts as a suppressor during abdominal aortic aneurysm via inhibition of KDM3A-mediated BNIP3

AIMS

Abdominal aortic aneurysm (AAA) is a serious disorder with a high disability rates and mortality rates. Accumulating evidence has identified the vital functions of microRNAs (miRNAs) in the treatment of AAA. Hence, this study is aimed at exploring the modulatory role of miR-194 in the development of AAA.

MAIN METHODS

After the establishment of mouse AAA models, the expression of miR-194 was determined by quantitative reverse transcription polymerase chain reaction (RT-qPCR), while lysine demethylase 3A (KDM3A) was determined by Western blot analysis in vascular smooth muscle cells (VSMCs) from the abdominal aorta. Cell apoptosis, levels of inflammatory factors as well as expressions of matrix metallopeptidase 2 (MMP2) and matrix metallopeptidase 9 (MMP9) were measured after altering the expression of miR-194 and KDM3A in VSMCs. Moreover, the interactions among miR-194, KDM3A, and BCL2 interacting protein 3 (BNIP3) were investigated by chromatin immunoprecipitation (ChIP) assay and dual-luciferase reporter gene assay.

KEY FINDINGS

miR-194 was poorly expressed while the expression of KDM3A was up-regulated in mice with AAA. miR-194 inhibited the expression of KDM3A while BNIP3 was positively mediated by KDM3A. More importantly, the number of macrophages was significantly reduced whereas the rate of apoptosis in VSMCs was enhanced. miR-194 reduced the inflammatory response and oxidative stress by repressing KDM3A-mediated BNIP3 expression.

SIGNIFICANCES

miR-194 played a suppressive role in the progression of AAA by inhibiting the expression of BNIP3 via KDM3A, representing a promising target for AAA management.

Intermittent PTH Administration Increases Bone-Specific Blood Vessels and Surrounding Stromal Cells in Murine Long Bones

To verify whether PTH acts on bone-specific blood vessels and on cells surrounding these blood vessels, 6-week-old male mice were subjected to vehicle (control group) or hPTH [1-34] (20 µg/kg/day, PTH group) injections for 2 weeks. Femoral metaphyses were used for histochemical and immunohistochemical studies. In control metaphyses, endomucin-positive blood vessels were abundant, but αSMA-reactive blood vessels were scarce. In the PTH-administered mice, the lumen of endomucin-positive blood vessels was markedly enlarged. Moreover, many αSMA-positive cells were evident near the blood vessels, and seemed to derive from those vessels. These αSMA-positive cells neighboring the blood vessels showed features of mesenchymal stromal cells, such as immunopositivity for c-kit and tissue nonspecific alkaline phosphatase (TNALP). Thus, PTH administration increased the population of perivascular/stromal cells positive for αSMA and c-kit, which were likely committed to the osteoblastic lineage. To understand the cellular events that led to increased numbers and size of bone-specific blood vessels, we performed immunohistochemical studies for PTH/PTHrP receptor and VEGF. After PTH administration, PTH/PTHrP receptor, VEGF and its receptor flk-1 were consistently identified in both osteoblasts and blood vessels (endothelial cells and surrounding perivascular cells). Our findings suggest that exogenous PTH increases the number and size of bone-specific blood vessels while fostering perivascular/stromal cells positive for αSMA/TNALP/c-kit.

Targeting mitochondrial fission as a potential therapeutic for abdominal aortic aneurysm

AIMS

Angiotensin II (AngII) is a potential contributor to the development of abdominal aortic aneurysm (AAA). In aortic vascular smooth muscle cells (VSMCs), exposure to AngII induces mitochondrial fission via dynamin-related protein 1 (Drp1). However, pathophysiological relevance of mitochondrial morphology in AngII-associated AAA remains unexplored. Here, we tested the hypothesis that mitochondrial fission is involved in the development of AAA.

METHODS AND RESULTS

Immunohistochemistry was performed on human AAA samples and revealed enhanced expression of Drp1. In C57BL6 mice treated with AngII plus β-aminopropionitrile, AAA tissue also showed an increase in Drp1 expression. A mitochondrial fission inhibitor, mdivi1, attenuated AAA size, associated aortic pathology, Drp1 protein induction, and mitochondrial fission but not hypertension in these mice. Moreover, western-blot analysis showed that induction of matrix metalloproteinase-2, which precedes the development of AAA, was blocked by mdivi1. Mdivi1 also reduced the development of AAA in apolipoprotein E-deficient mice infused with AngII. As with mdivi1, Drp1+/- mice treated with AngII plus β-aminopropionitrile showed a decrease in AAA compared to control Drp1+/+ mice. In abdominal aortic VSMCs, AngII induced phosphorylation of Drp1 and mitochondrial fission, the latter of which was attenuated with Drp1 silencing as well as mdivi1. AngII also induced vascular cell adhesion molecule-1 expression and enhanced leucocyte adhesion and mitochondrial oxygen consumption in smooth muscle cells, which were attenuated with mdivi1.

CONCLUSION

These data indicate that Drp1 and mitochondrial fission play salient roles in AAA development, which likely involves mitochondrial dysfunction and inflammatory activation of VSMCs.

Physical interaction of tropomyosin 3 and STIM1 regulates vascular smooth muscle contractility and contributes to hypertension

SCOPE

Tropomyosin (TPM), an actin-binding protein widely expressed across different cell types, is primarily involved in cellular contractile processes. We investigated whether TPM3 physically and functionally interacts with stromal interaction molecule 1 (STIM1) to contribute to vascular smooth muscle cell (VSMC) contraction, store-operated calcium entry (SOCE), and high-salt intake-induced hypertension in rats.

METHODS AND RESULTS

Analysis of a rat RNA-seq data set of 80 samples showed that the STIM1 and Tpm3 transcriptome expression pattern is highly correlated, and co-immunoprecipitation results indicated that TPM3 and STIM1 proteins physically interacted in rat VSMCs. Immunohistochemical data displayed obvious co-localization of TPM3 and STIM1 in rat VSMCs. Knockdown of TPM3 or STIM1 in VSMCs with specific small interfering RNA significantly suppressed contractions in tension measurement assays and decreased SOCE in calcium assays. Rats fed a high-salt diet for 4 weeks had significantly higher systolic blood pressure than controls, with significantly increased contractility and markedly increased TPM3 and STIM1 expression levels in the mesenteric resistance artery (shown by tension measurements and immunoblotting, respectively). Additionally, high salt environment in vitro induced significant enhancement of TPM3 and STIM1 expression levels in VSMCs.

CONCLUSIONS

We showed for the first time that TPM3 and STIM1 physically and functionally interact to contribute to VSMC contraction, SOCE, and high-salt intake-induced hypertension. Our findings provide mechanistic insights and offer a potential therapeutic target for high-salt intake-induced hypertension.

Implications for MicroRNA involvement in the prognosis and treatment of atherosclerosis

MicroRNAs (miRNAs) are important molecules which implicated in various processes, such as differentiation, development, cell survival, cell apoptosis and also cell metabolism. Investigations over decades have revealed that various genes and signaling pathways are implicated in beginning and development of atherosclerosis, several miRNAs being involved in these dysregulated genes and pathways. miRNAs have provided new molecular vision in the context of atherosclerosis. miRNAs are considered as important regulators of cellular migration, differentiation, proliferation, lipid uptake and efflux, as well as cytokine production. Application of miRNAs as a biomarker in diagnosis, prognosis and even therapy is quiet exciting. Although animal researches showed promising results, still some practical difficulties and technical challenges need to be addressed before translation from researches into clinical practices. In this review, we present important data about three critical cells endothelial cell (EC), vascular smooth muscle cell (VSMC), and monocyte/macrophage and regulation of these cells through miRNAs. Furthermore, we discuss about the potential of miRNAs as a prognostic and diagnostic biomarkers, therapeutic opportunities and challenges, and also future perspective.

Quercetin-induced apoptosis ameliorates vascular smooth muscle cell senescence through AMP-activated protein kinase signaling pathway

Aging is one of the risk factors for the development of cardiovascular diseases. During the progression of cellular senescence, cells enter a state of irreversible growth arrest and display resistance to apoptosis. As a flavonoid, quercetin induces apoptosis in various cells. Accordingly, we investigated the relationship between quercetin-induced apoptosis and the inhibition of cellular senescence, and determined the mechanism of oxidative stress-induced vascular smooth muscle cell (VSMC) senescence. In cultured VSMCs, hydrogen peroxide (H₂O₂) dose-dependently induced senescence, which was associated with increased numbers of senescence-associated β-galactosidase-positive cells, decreased expression of SMP30, and activation of p53-p21 and p16 pathways. Along with senescence, expression of the anti-apoptotic protein Bcl-2 was observed to increase and the levels of proteins related to the apoptosis pathway were observed to decrease. Quercetin induced apoptosis through the activation of AMP-activated protein kinase. This action led to the alleviation of oxidative stress-induced VSMC senescence. Furthermore, the inhibition of AMPK activation with compound C and siRNA inhibited apoptosis and aggravated VSMC senescence by reversing p53-p21 and p16 pathways. These results suggest that senescent VSMCs are resistant to apoptosis and quercetin-induced apoptosis attenuated the oxidative stress-induced senescence through activation of AMPK. Therefore, induction of apoptosis by polyphenols such as quercetin may be worthy of attention for its anti-aging effects.

Persulfidation of transcription factor FOXO1 at cysteine 457: A novel mechanism by which H2S inhibits vascular smooth muscle cell proliferation

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FOXO1 is involved in the inhibitory effect of H₂S on vascular smooth muscle cell proliferation.

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H₂S inhibits vascular smooth muscle cell proliferation by maintaining FOXO1 activity.

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H₂S preserves FOXO1 activity by persulfidation.

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H₂S persulfidates FOXO1 at Cys457 and subsequently prevents FOXO1 phosphorylation at Ser256.

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The results provide new ideas for therapeutic strategies for anti-vascular remodeling.

Introduction

The proliferation of vascular smooth muscle cells (VSMCs) is an important physiological and pathological basis for many cardiovascular diseases. Endogenous hydrogen sulfide (H₂S), the third gasotransmitter, is found to preserve vascular structure by inhibiting VSMC proliferation. However, the mechanism by which H₂S suppresses VSMC proliferation has not been fully clear.

Objectives

This study aimed to explore whether H₂S persulfidates the transcription factor FOXO1 to inhibit VSMC proliferation.

Methods

After the proliferation of VSMC A7r5 cells was induced by endothelin-1 (ET-1), FOXO1 phosphorylation and proliferating cell nuclear antigen (PCNA) expression were detected by Western blotting, the degree of FOXO1 nuclear exclusion and PCNA fluorescent signals in the nucleus were detected by immunofluorescence, and the persulfidation of FOXO1 was measured through a biotin switch assay.

Results

The results showed that ET-1 stimulation increased cell proliferation, FOXO1 phosphorylation and FOXO1 nuclear exclusion to the cytoplasm in the cells. However, pretreatment with NaHS, an H₂S donor, successfully abolished the ET-1-induced increases in the VSMC proliferation, FOXO1 phosphorylation, and FOXO1 nuclear exclusion to the cytoplasm. Mechanistically, H₂S persulfidated the FOXO1 protein in A7r5 and 293T cells, and the thiol reductant DTT reversed this effect. Furthermore, the C457S mutation of FOXO1 abolished the H₂S-induced persulfidation of FOXO1 in the cells and the subsequent inhibitory effects on FOXO1 phosphorylation at Ser256, FOXO1 nuclear exclusion to the cytoplasm and cell proliferation.

Conclusion

Thus, our findings demonstrated that H₂S might inhibit VSMC proliferation by persulfidating FOXO1 at Cys457 and subsequently preventing FOXO1 phosphorylation at Ser256.

TRPV5 attenuates abdominal aortic aneurysm in mice by regulating KLF4-dependent phenotype switch of aortic vascular smooth muscle cells

Abdominal aortic aneurysm (AAA) is a fatal vascular disease with insidious symptoms. However, the mechanism behind its development remains unclear. The transient receptor potential vanilloid (TRPV) family has crucial protective effects against cardiovascular diseases, but the role of TRPV5 in AAA has yet to be reported. In this study, ApoE^-/- mice were intraperitoneally injected with AAV-GFP or AAV-TRPV5. After 30 days, mice were further administered with angiotensin II (Ang II, 1.44 mg/kg/day) by using osmotic pumps to induce the AAA model or Saline for 28 days, (i.e., Saline + AAV-GFP, Saline + AAV-TRPV5, Ang II + AAV-GFP and Ang II + AAV-TRPV5 groups were established). Compared with the control group, the incidence of AAA and the maximal diameter of the abdominal aorta markedly decreased in Ang II + AAV-TRPV5, which was detected by vascular ultrasound at 28 day. Meanwhile, less collagen and elastin degradation were observed in the Ang II + AAV-TRPV5 group by using Masson and Elastin stains. Moreover, more α-SMA and less MMP2 was observed in the abdominal aortas collected at 28 day by immunohistochemistry. In vitro, primary mouse vascular smooth muscle cells (VSMCs) were treated with Ang II (1 μM) to induce phenotype switch. Sh-TRPV5 and AdTRPV5 were used to transfect VSMCs. PCR and Western blotting were used to access the expression of contractile marker, including α-SMA and SM-22α. The results showed that the mRNA and protein level of α-SMA and SM-22α were decreased under the stimulation of Ang II, but could be attenuated by TRPV5 overexpression. The cell scratch assay demonstrated that the migration ability of VSMCs was increased in Ang II treated group and could be ameliorated by TRPV5 overexpression. Above all, VSMCs transformed from the contractile into secretory phenotype under Ang II stimuli, but could be rescued by TRPV5 overexpression. Furthermore, TRPV5 overexpression suppressed the increased expression of KLF4 induced by Ang II treatment in VSMCs. The data demonstrated that TRPV5 could inhibit AAA formation and play a critical role in the VSMC phenotype switch by downregulating KLF4, suggesting TRPV5 as a new strategy for treating AAA.

Long non-coding RNA LOC285194 inhibits proliferation and migration but promoted apoptosis in vascular smooth muscle cells via targeting miR-211/PUMA and TGF-β1/S100A4 signal

Long non-coding RNA LOC285194 (LOC285194) has reported to regulate vascular smooth muscle cells (VSMCs) proliferation and apoptosis in vitro and in vivo. Here we aimed to determine the role of LOC285194 in the proliferation, migration and apoptosis of VSMCs and its underlying mechanisms. A7r5 cells were transfected with Lv-LOC285194 or control Lv-NC for 24-72 h, or small interfering RNA targeting S100A4 (S100A4 siRNA) for 24-48 h, or co-transfected with Lv-LOC285194 and PUMA siRNA for 72 h, or treated with miR-211 inhibitor or co-transfected with Lv-LOC285194 and miR-211 mimics for 72 h. A7r5 cells were also treated with transforming growth factor - β(TGF-β) (5 ng/ml) after Lv-LOC285194 transfection for 24 h. The relationship between LOC285194 and TGF-β was confirmed using luciferase reporter assay. Cell proliferation and cell apoptosis were analyzed by Cell Counting Kit-8 (CCK-8) assay, ELISA and TUNEL staining. LOC285194 and miR-211 expression were detected by qPCR assay. S100A4, pro-apoptotic and anti-apoptotic protein were detected by Western blot assay. LOC285194 inhibited cell proliferation, invasion and migration and promoted cell apoptosis accompanied by upregulation of PUMA and downregulation of miR-211 and S100A4. Targeting PUMA reversed the effect of LOC285194 on cell apoptosis and proliferation. miR-211 mimic inhibited LOC285194-induced PUMA upregulation and decreased LOC285194-induced cell apoptosis. TGF-β (5 ng/ml) treatment reversed S100A4 siRNA or LOC285194-induced S100A4 expression. Luciferase reporter assay showed that TGF-β was the target of LOC285194. LOC285194 inhibits proliferation and promoted apoptosis in vascular smooth muscle cells via targeting miR-211/PUMA signal; In addition, LOC285194 decreased cell invasion and migration by targeting TGF-β1/S100A4 signal.

Vascular Kv7 channels control intracellular Ca2+ dynamics in smooth muscle

Voltage-gated Kv7 (or KCNQ) channels control activity of excitable cells, including vascular smooth muscle cells (VSMCs), by setting their resting membrane potential and controlling other excitability parameters. Excitation-contraction coupling in muscle cells is mediated by Ca2+ but until now, the exact role of Kv7 channels in cytosolic Ca2+ dynamics in VSMCs has not been fully elucidated. We utilised microfluorimetry to investigate the impact of Kv7 channel activity on intracellular Ca2+ levels and electrical activity of rat A7r5 VSMCs and primary human internal mammary artery (IMA) SMCs. Both, direct (XE991) and G protein coupled receptor mediated (vasopressin, AVP) Kv7 channel inhibition induced robust Ca2+ oscillations, which were significantly reduced in the presence of Kv7 channel activator, retigabine, L-type Ca2+ channel inhibitor, nifedipine, or T-type Ca2+ channel inhibitor, NNC 55-0396, in A7r5 cells. Membrane potential measured using FluoVolt exhibited a slow depolarisation followed by a burst of sharp spikes in response to XE991; spikes were temporally correlated with Ca2+ oscillations. Phospholipase C inhibitor (edelfosine) reduced AVP-induced, but not XE991-induced Ca2+ oscillations. AVP and XE991 induced a large increase of [Ca2+]i in human IMA, which was also attenuated with retigabine, nifedipine and NNC 55-0396. RT-PCR, immunohistochemistry and electrophysiology suggested that Kv7.5 was the predominant Kv7 subunit in both rat and human arterial SMCs; CACNA1C (Cav1.2; L-type) and CACNA1 G (Cav3.1; T-type) were the most abundant voltage-gated Ca2+ channel gene transcripts in both types of VSMCs. This study establishes Kv7 channels as key regulators of Ca2+ signalling in VSMCs with Kv7.5 playing a dominant role.