Valsartan inhibits angiotensin II-induced proliferation of vascular smooth muscle cells via regulating the expression of mitofusin 2

Sacubitril/valsartan inhibits the proliferation of vascular smooth muscle cells through notch signaling and ERK1/2 pathway

AIMS

To explore the role and mechanism of Notch signaling and ERK1/2 pathway in the inhibitory effect of sacubitril/valsartan on the proliferation of vascular smooth muscle cells (VSMCs).

MAIN METHODS

Human aortic vascular smooth muscle cells (HA-VSMCs) were cultured in vitro. The proliferating VSMCs were divided into three groups as control group, Ang II group and Ang II + sacubitril/valsartan group. Cell proliferation and migration were detected by CCK8 and scratch test respectively. The mRNA and protein expression of PCNA, MMP-9, Notch1 and Jagged-1 were detected by qRT-PCR and Western blot respectively. The p-ERK1/2 expression was detected by Western blot.

KEY FINDINGS

Compared with the control group, proliferation and migration of VSMCs and the expression of PCNA, MMP-9, Notch1, Jagged-1 and p-ERK1/2 was increased in Ang II group. Sacubitril/valsartan significantly reduced the proliferation and migration. Additionally, pretreatment with sacubitril/valsartan reduced the PCNA, MMP-9, Notch1, Jagged-1 and p-ERK1/2 expression.

Role of Mitochondrial Dynamics in Heart Diseases

Mitochondrial dynamics, including fission and fusion processes, are essential for heart health. Mitochondria, the powerhouses of cells, maintain their integrity through continuous cycles of biogenesis, fission, fusion, and degradation. Mitochondria are relatively immobile in the adult heart, but their morphological changes due to mitochondrial morphology factors are critical for cellular functions such as energy production, organelle integrity, and stress response. Mitochondrial fusion proteins, particularly Mfn1/2 and Opa1, play multiple roles beyond their pro-fusion effects, such as endoplasmic reticulum tethering, mitophagy, cristae remodeling, and apoptosis regulation. On the other hand, the fission process, regulated by proteins such as Drp1, Fis1, Mff and MiD49/51, is essential to eliminate damaged mitochondria via mitophagy and to ensure proper cell division. In the cardiac system, dysregulation of mitochondrial dynamics has been shown to cause cardiac hypertrophy, heart failure, ischemia/reperfusion injury, and various cardiac diseases, including metabolic and inherited cardiomyopathies. In addition, mitochondrial dysfunction associated with oxidative stress has been implicated in atherosclerosis, hypertension and pulmonary hypertension. Therefore, understanding and regulating mitochondrial dynamics is a promising therapeutic tool in cardiac diseases. This review summarizes the role of mitochondrial morphology in heart diseases for each mitochondrial morphology regulatory gene, and their potential as therapeutic targets to heart diseases.

Pers reverse angiotensin II -induced vascular smooth muscle cell proliferation by targeting cyclin E expression via inhibition of the MAPK signaling pathway

The circadian rhythm of blood pressure (BP) is believed to be regulated by the clock system, which is closely linked to levels of angiotensin II (Ang II). This study aimed to investigate whether Ang II mediates the proliferation of vascular smooth muscle cells (VSMCs) through the interaction between the clock system and the mitogen-activated protein kinase (MAPK) signaling pathway. Primary rat aortic VSMCs were treated with Ang II, with or without MAPK inhibitors. VSMC proliferation, expression of clock genes, CYCLIN E, and MAPK pathways were assessed. Ang II treatment resulted in increased VSMC proliferation and rapid upregulation of clock gene Periods (Pers) expression. Compared to the non-diseased control (NC) group, VSMCs incubated with Ang II displayed a noticeable delay in the G1/S phase transition and downregulation of CYCLIN E upon silencing of Per1 and Per2 genes. Importantly, silencing Per1 or Per2 in VSMCs led to decreased expression of key MAPK pathway proteins, including RAS, phosphorylated mitogen-activated protein kinase (P-MEK), and phosphorylated extracellular signal-regulated protein kinase (P-ERK). Moreover, the MEK and ERK inhibitors, U0126 and SCH772986, significantly attenuated the Ang II-induced proliferation of VSMCs, as evidenced by an increased G1/S phase transition and decreased CYCLIN E expression. The MAPK pathway plays a critical role in regulating VSMC proliferation in response to Ang II stimulation. This regulation is controlled by the expression of circadian clock genes involved in the cell cycle. These findings provide novel insights for further research on diseases associated with abnormal VSMC proliferation.

Current Understanding of the Pivotal Role of Mitochondrial Dynamics in Cardiovascular Diseases and Senescence

The heart is dependent on ATP production in mitochondria, which is closely associated with cardiovascular disease because of the oxidative stress produced by mitochondria. Mitochondria are highly dynamic organelles that constantly change their morphology to elongated (fusion) or small and spherical (fission). These mitochondrial dynamics are regulated by various small GTPases, Drp1, Fis1, Mitofusin, and Opa1. Mitochondrial fission and fusion are essential to maintain a balance between mitochondrial biogenesis and mitochondrial turnover. Recent studies have demonstrated that mitochondrial dynamics play a crucial role in the development of cardiovascular diseases and senescence. Disruptions in mitochondrial dynamics affect mitochondrial dysfunction and cardiomyocyte survival leading to cardiac ischemia/reperfusion injury, cardiomyopathy, and heart failure. Mitochondrial dynamics and reactive oxygen species production have been associated with endothelial dysfunction, which in turn causes the development of atherosclerosis, hypertension, and even pulmonary hypertension, including pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. Here, we review the association between cardiovascular diseases and mitochondrial dynamics, which may represent a potential therapeutic target.

Biological evaluation of linalool on the function of blood vessels

Long-term hypertension leads to alterations in the structure and function of blood vessels, and abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are important factors for these changes. Linalool is a natural compound extracted from plants. The present study aimed to explore the role and underlying mechanism of linalool in the physiological behavior of VSMCs. Angiotensin II (Ang II) was utilized to treat VSMCs, and MTT and western blotting assays were then employed to detect the effect of linalool on the induced proliferation and migration of VSMCs. The target gene of linalool was predicted by the SwissTargetPrediction website, and its expression level in VSMCs was determined using reverse transcription-quantitative PCR and western blotting. Next, the role of the target gene in the physiological behavior of VSMCs treated with linalool was examined, and the signaling pathway was explored. The results revealed that the proliferation and migration of VSMCs treated with Ang II were significantly promoted, and linalool could alleviate these effects in a dose-dependent manner. Cholinergic receptor muscarinic 3 (CHRM3), as a predicted target, was found to be highly expressed in Ang II-induced VSMCs, and CHRM3 overexpression could prevent the inhibitory effect of linalool on cell proliferation and migration. In addition, its overexpression caused an increase in the expression of proteins related to the MAPK signaling pathway. In conclusion, linalool inhibited the proliferation and migration of Ang II-induced VSMCs and blocked the MAPK signaling pathway by downregulating CHRM3.

Mitofusion 2 Overexpression Decreased Proliferation of Human Embryonic Lung Fibroblasts in Acute Respiratory Distress Syndrome through Inhibiting RAS-RAF-1-ERK1/2 Pathway

Acute respiratory distress syndrome (ARDS) is one of the most fatal diseases worldwide. Pulmonary fibrosis occurs early in ARDS, and its severity plays a crucial role in ARDS mortality rate. Some studies suggested that fibroproliferation is an essential mechanism in ARDS. Mitofusion2 (Mfn2) overexpression plays a role in inhibiting cell proliferation. However, the role and potential mechanism of Mfn2 on the proliferation of fibroblasts is still unknown. In this study, we aimed at exploring the effect of Mfn2 on the human embryonic lung fibroblasts (HELF) and discussed its related mechanism. The HELF were treated with the Mfn2 overexpressing lentivirus (adv-Mfn2). The cell cycle was detected by flow cytometry. MTT, PCR and Western blotting were used to investigate the effect of Mfn2 on the proliferation of the HELF, collagen expression, the RAS-RAF-1-ERK1/2 pathway and the expression of cycle-related proteins (p21, p27, Rb, Raf-1, p-Raf-1, Erk1/2 and p-Erk1/2). The co-immunoprecipitation assay was used to explore the interaction between Mfn2 and Ras. The results showed that the overexpression of Mfn2 inhibited the proliferation of the HELF and induced the cell cycle arrest at the G₀/G₁ phase. Meanwhile, Mfn2 also inhibited the expression of collagen I, p-Erk and p-Raf-1. In addition, an interaction between Mfn2 and Ras existed in the HELF. This study suggests that the overexpression of Mfn2 can decrease the proliferation of HELF in ARDS, which was associated with the inhibition of the RAS-RAF-1-ERK1/2 pathway. The results may offer a potential therapeutic intervention for patients with ARDS.

Angiotensin II Receptor Type 1 Antagonists Modulate Vascular Smooth Muscle Cell Proliferation and Migration via AMPK/mTOR

The aberrant proliferation and migration of vascular smooth muscle cells (VSMCs) in the vascular wall are crucial pathological events involved in cardiovascular impairments including hypertension, heart failure, and atherosclerosis. At the molecular level, the mammalian target of rapamycin (mTOR)-ribosomal protein S6 kinase beta-1 (p70S6K) signaling pathway is essential to potentiate VSMC proliferation and migration. Although angiotensin II receptor type 1 ­(AT1-R) antagonists such as valsartan and telmisartan have a significant cardiovascular protective effect, the molecular basis of this class of drugs in VSMC proliferation and migration remains elusive. By using cultured VSMCs, adenosine monophosphate-activated protein kinase (AMPK) α2 knockout mice, and hypertensive rat models, this study investigated whether AT1-R antagonists can inhibit the mTOR-p70S6K signaling pathway in VSMCs and the vascular wall. Valsartan activated AMPK, which in turn suppressed reactive oxygen species production and consequently attenuated VSMC proliferation and migration. In vivo, a clinical dose of telmisartan significantly inhibited the mTOR-p70S6K signaling pathway in the vascular wall of wild-type but not AMPKα2–/– mice. Furthermore, spontaneously hypertensive rats had significantly elevated phosphorylation of mTOR and p70S6K in the aorta compared to Wistar-Kyoto rats, which were reduced by telmisartan administration. These data suggest that AT1-R antagonists inhibit VSMC proliferation and migration via their regulation of AMPK, mTOR, and p70S6K, which contribute to the cardioprotective effects of these drugs.

Shexiang Baoxin Pill Alleviates the Atherosclerotic Lesions in Mice via Improving Inflammation Response and Inhibiting Lipid Accumulation in the Arterial Wall

Epidemiological studies have demonstrated that cardiovascular diseases (CVDs) are the leading cause of death in the world. Atherosclerosis, a kind of chronic vascular disorder related to multiple pathogenic processes, has been reported to be an underlying cause of CVDs. Shexiang Baoxin Pill (SBP) is a traditional Chinese medicine formulation and has been broadly used for the treatment of CVDs in East Asia. However, whether SBP affects the development of atherosclerosis is poorly understood. The aim of this study was to investigate the antiatherosclerotic roles and relevant mechanisms of SBP in apolipoprotein E knockout mice. Our results showed that SBP treatment markedly decreased the size of atherosclerotic plaques of the entire aorta and the aortic sinus. Biochemical analyses indicated that SBP gavage improved oxidative stress in vivo, as seen by the level elevation of SOD, CAT, and GSH and the level reduction of MDA, H₂O₂, and MPO. Moreover, the concentration of MCP-1, IFN-γ, and IL-17A was reduced, and the content of IL-10 and TGF-β1 was increased in the serum from SBP-treated mice. We discovered that the expression levels of inflammatory factors including VCAM-1, ICAM-1, IL-6, and IL-2 in the vascular wall of the SBP group were also decreased in comparison with those of the normal saline group. Moreover, we found that SBP alleviated the activation of inflammation-related pathways in the aorta tissue, as seen by the level elevation of Mfn2 and reduced phosphorylation of p38, JNK, and NF-κB. Furthermore, western blot showed that SBP administration reduced the level of SR-A and LOX-1 and elevated the content of LXRα, ABCA1, and ABCG1 in the arterial wall, indicating that SBP was capable of alleviating lipid influx and facilitating lipid efflux. In conclusion, our data suggested that SBP exerted antiatherosclerotic effects via improving inflammation response and inhibiting lipid accumulation.

Overexpression of Mitofusin2 decreased the reactive astrocytes proliferation in vitro induced by oxygen-glucose deprivation/reoxygenation

Glia scar is a hallmark in late-stage of brain stroke disease, which hinder axonal regeneration and neuronal repair. Mitofusin2 (Mfn2) is a newly found cellular proliferation inhibitor. This study is to elucidate the role of Mfn2 in reactive astrocytes induced by oxygen-glucose deprivation/reoxygenation(OGD/R) model in vitro. Up-expression in EdU staining and protein level of GFAP, PCNA and CyclinD1, demonstrates the distinct activation and proliferation of astrocytes after the stimulation of OGD/R. Meanwhile, Mfn2 was proved to be down-regulated both in gene and protein levels. Pretreatment of cells with adenoviral vector encoding Mfn2 gene increased Mfn2 expression and subsequently attenuated OGD-induced astrocyte proliferation. Down-regulation of Ras-p-Raf1-p-ERK1/2 pathway and cell cycle arrest were found to be relevant. Together, these results suggested that overexpression of Mfn2 can effectively inhibit the proliferation of reactive astrogliosis, which might contribute to a promising therapeutic intervention in cerebral ischemic injury.

Selection of a high-affinity and in vivo bioactive ssDNA aptamer against angiotensin II peptide

Unique features of aptamers have attracted interests for a broad range of applications. Aptamers are able to specifically bind to targets and inhibit their functions. This study, aimed to isolate the high affinity ssDNA aptamers against bio-regulator peptide angiotensin II (Ang II) and investigate their bioactivity in cellular and animal models. To isolate ssDNA aptamers, 12 rounds of affinity chromatography SELEX (Systematic Evolution of Ligands by EXponential enrichment) procedure were carried out. The SPR (surface plasmon resonance) and ELONA (enzyme linked oligonucleotide assay) analysis were used to determine the affinity and specificity of aptamers. The ability of selected aptamers to inhibit the proliferative effect of Ang II on human aortic vascular smooth muscle cells (HA-VSMCs) and their performance on Wistar rat urinary system and serum electrolyte levels were investigated. Two full-length aptamers (FLC112 and FLC125) with high affinity of respectively 7.52±2.44E-10 and 5.87±1.3E-9M were isolated against Ang II. The core regions of these aptamers (CRC112 and CRC125) also showed affinity of 5.33±1.15E-9 and 4.11±1.09E-9M. In vitro analysis revealed that FLC112 and FLC125 can inhibit the proliferative effect of Ang II on HA-VSMCs (P<0.05). They also significantly reduced the serum sodium level and increased the urine volume (P<0.05). The core regions of aptamers did not show high inhibitory potential against Ang II. It can be a spotlight that ssDNA aptamers have high potential for blocking Ang II. In conclusion, it appears that the researches focusing on high affinity and bioactive aptamers may lead to excellent results in blocking Ang II activity.

Inhibiting (pro)renin receptor-mediated p38 MAPK signaling decreases hypoxia/reoxygenation-induced apoptosis in H9c2 cells

The (pro)renin receptor is a new molecular member of the renin-angiotensin system and participates in regulating many physiological and pathological processes. However, the role of (pro)renin receptor-mediated signaling pathways in myocardial ischemic/reperfusion injury remains unclear. In this study, we hypothesized that p38 mitogen-activated protein kinase (MAPK) signaling pathway activation by the (pro)renin receptor had effects on myocardial apoptosis induced by ischemia/reperfusion. This analysis was performed using a hypoxia/reoxygenation model in H9c2 cells to mimic ischemia/reperfusion injury. The H9c2 rat cardiomyocyte cell line was subjected to 2 h of hypoxia followed by 6 h of reoxygenation. The (pro)renin receptor, caspase 3, and phosphorylated p38 MAPK protein expression levels were analyzed by Western blot. After 2 h of hypoxia followed by 6 h of reoxygenation, apoptosis increased in H9c2 cells; the (pro)renin receptor, caspase 3, and phosphorylated p38 MAPK protein expressions were upregulated. siRNA silencing of the (pro)renin receptor significantly decreased p38 MAPK phosphorylation. siRNA silencing of the (pro)renin receptor and treatment with the p38MAPK inhibitor SB203580 significantly decreased the hypoxia/reoxygenation-induced apoptosis and caspase 3 protein expression in H9c2 cells. Furthermore, we found that the role of the (pro)renin receptor was independent of angiotensin II (Ang II). Thus, we concluded that (pro)renin receptor activation could trigger hypoxia/reoxygenation-induced apoptosis in H9c2 cells, partially through the p38 MAPK/caspase 3 signaling pathway, independent of Ang II. Therefore, this study may provide new therapeutic targets for myocardial ischemic/reperfusion injury prevention, and further in vivo studies are needed.

Valsartan decreases neointimal hyperplasia in balloon-injured rat aortic arteries by upregulating HO-1 and inhibiting angiotensin II type 1 receptor

AIMS

Upregulation of heme oxygenase (HO)-1 plays an important role in vascular protection. Valsartan attenuates neointimal hyperplasia in animal studies. The objective of this study was to examine the role of HO-1 and angiotensin II type 1 (AT1) receptor in the action of valsartan on neointimal hyperplasia in balloon-injured rat aortic arteries.

MAIN METHODS

Thirty-six male Wistar rats were randomly divided into the following three groups with twelve rats in each group: control group, surgery (model) group, and valsartan group. Aortic balloon injury was performed to elicit endothelial denudation with a 2F balloon catheter. On days 14 and 28 after injury, blood was harvested to measure bilirubin levels. Aortic arteries were harvested for morphometry analysis, to determine angiotensin II (Ang II) level, and to analyze mRNA or protein expression.

KEY FINDINGS

Compared with the control group, proliferation and intimal thickening of vascular smooth muscle cells (VSMCs) were obvious in the surgery group rats on days 14 and 28 after injury. Valsartan significantly reduced the proliferation and intimal thickening. Additionally, pretreatment with valsartan significantly reduced Ang II levels, AT1 receptor, and p38 mitogen-activated protein kinase (MAPK) expression. Valsartan increased HO-1 protein and mRNA expression, as well as increased serum bilirubin levels compared with the surgery group.

SIGNIFICANCE

Valsartan treatment decreased neointimal hyperplasia in balloon-injured rats. The mechanism of action might be linked to the upregulation of HO-1, downregulation of AT1 receptor and inhibition of p38MAPK signal pathway.

Epigallocatechin-3-gallate inhibits proliferation of human aortic smooth muscle cells via up-regulating expression of mitofusin 2

Previous studies have shown that epigallocatechin-3-gallate (EGCG) inhibits the proliferation of vascular smooth muscle cells (VSMCs) via the extracellular-signal-regulated kinase (ERK1/2) and mitogen activated protein kinases (MAPKs) pathway. Mitofusin 2 (Mfn-2) also suppresses VSMC proliferation through Ras-Raf-ERK/MAPK, suggesting a possible link between EGCG, Mfn-2 and ERK/MAPK. However, the effect of EGCG on Mfn-2 remains unknown. In this study, we investigated the role of Mfn-2 in the regulation of VSMC proliferation by EGCG, and assessed the underlying mechanisms. The effects of EGCG on the proliferation of cultured human aortic smooth muscle cells (HASMCs) were observed by 5-ethynl-2-deoxyuridine (EdU) incorporation assay. Mfn-2 gene and protein levels, and Ras, p-c-Raf and p-ERK1/2 protein levels were determined by quantitative real-time polymerase chain reaction and western blotting, respectively. Mfn-2 gene silencing was achieved by RNA interference. EGCG 50 μmol/L profoundly inhibited the proliferation of HASMCs in culture, up-regulated Mfn-2, and down-regulated the expression of p-c-Raf and p-ERK1/2. Furthermore, RNA interference-mediated gene knockdown of Mfn-2 antagonized EGCG-induced anti-proliferation and down-regulation of Ras, p-c-Raf and p-ERK1/2. These results suggest that EGCG inhibits the proliferation of HASMCs in vitro largely via Mfn-2-mediated suppression of the Ras-Raf-ERK/MAPK signaling pathway.