Promote Vascular Smooth Muscle Cells Migration Research Articles

A novel protein encoded by circLARP1B promotes the proliferation and migration of vascular smooth muscle cells by suppressing cAMP signaling

Background and aimsCircular RNA (circRNA) is closely related to atherosclerosis (AS) incidence and progression, but its regulatory mechanism in AS needs further elucidation. AS development is significantly influenced by abnormal vascular smooth muscle cells (VSMCs) growth and migration. This study explored the potential protein role of circLARP1B in VSMC proliferation and migration. MethodsWe performed whole-transcriptome sequencing in human normal arterial intima and advanced atherosclerotic plaques to screen for differentially expressed circRNAs. The sequencing results were combined with database analysis to screen for circRNAs with coding ability. Real-time quantitative polymerase chain reaction was utilized to assess circLARP1B expression levels in atherosclerotic plaque tissues and cells. circLARP1B-243aa function and pathway in VSMCs growth and migration were studied by scratch, transwell, 5-ethynyl-2′-deoxyuridine, cell counting kit-8, and Western blot experiments. ResultsWe found that circLARP1B was downregulated in atherosclerotic plaque tissue and promoted the proliferation and migration of VSMCs. circLARP1B encodes a novel protein with a length of 243 amino acids. Through functional experiments, we confirmed the role of circLARP1B-243aa in enhancing VSMCs migration and proliferation. Mechanistically, circLARP1B-243aa promotes VSMCs migration and growth by upregulating phosphodiesterase 4C to inhibit the cyclic adenosine monophosphate signaling pathway. ConclusionsOur results suggested that circLARP1B could promote VSMCs growth and migration through the encoded protein circLARP1B-243aa. Therefore, it could be a treatment target and biomarker for AS.

Platelet-derived microvesicles drive vascular smooth muscle cell migration via forming podosomes and promoting matrix metalloproteinase-9 activity

We have shown that platelet-derived microvesicles (PMVs) induce abnormal proliferation, migration, and energy metabolism of vascular smooth muscle cells (VSMCs) after vascular intimal injury. Here, we examined a novel role of podosome in mediating matrix metalloproteinase-9 (MMP-9) dependent VSMC migration induced by platelet-derived microvesicles (PMVs). VSMCs were isolated from the thoracic aortas of male Sprague Dawley (SD) rats and identified with immunofluorescent staining. Blood samples were collected from SD Rats, the platelets were isolated with density gradient centrifugation from the blood samples and activated by collagen I. Intriguingly, proteins expressed in platelets were found to participate in the positive regulation of podosome assembly using GO analysis by DAVID, and most of the proteins were found in extracellular exosomes. Of note, activated platelets indirectly induced VSMC migration via releasing PMVs which was verified using platelets and VSMCs transwell co-culture system. Besides, podosome, an invasive protrusion to mediate extracellular matrix (ECM) remodeling, was formed in VSMCs to induce cell migration. Furthermore, MMP-9 activity detected by gelatin zymography was used to verify the function of the podosome in ECM remodeling. The result indicated that MMP-9 activity was robustly activated in VSMCs to implement the function of the podosome. In addition, gelatin degradation was detected in intact VSMCs using a gelatin degradation assay after co-culture with platelets. Taken together, our data reveal a novel mechanism that PMVs promote VSMC migration via forming podosomes and inducing MMP-9 activity.

The FAT1 Cadherin Drives Vascular Smooth Muscle Cell Migration.

Vascular smooth muscle cells (VSMCs) are normally quiescent and non-migratory, regulating the contraction and relaxation of blood vessels to control the vascular tone. In response to arterial injury, these cells become active; they proliferate, secrete matrix proteins, and migrate, and thereby contribute importantly to the progression of several cardiovascular diseases. VSMC migration specifically supports atherosclerosis, restenosis after catheter-based intervention, transplant vasculopathy, and vascular remodeling during the formation of aneurysms. The atypical cadherin FAT1 is expressed robustly in activated VSMCs and promotes their migration. A positive role of FAT1 in the migration of other cell types, including neurons, fibroblasts, podocytes, and astrocyte progenitors, has also been described. In cancer biology, however, the effect of FAT1 on migration depends on the cancer type or context, as FAT1 either suppresses or enhances cancer cell migration and invasion. With this review, we describe what is known about FAT1's effects on cell migration as well as the factors that influence FAT1-dependent migration. In VSMCs, these factors include angiotensin II, which activates FAT1 expression and cell migration, and proteins of the Atrophin family: Atrophin-1 and the short isoform of Atrophin-2, which promote VSMC migration, and the long isoform of Atrophin-2, which exerts negative effects on FAT1-dependent VSMC migration.

ETV2 Enhances CXCL5 Secretion from Endothelial Cells, Leading to the Promotion of Vascular Smooth Muscle Cell Migration.

Abnormal communication between endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) promotes vascular diseases, including atherogenesis. ETS variant transcription factor 2 (ETV2) plays a substantial role in pathological angiogenesis and the reprogramming of ECs; however, the role of ETV2 in the communication between ECs and VSMCs has not been revealed. To investigate the interactive role of ETV2 in the EC to VSMC phenotype, we first showed that treatment with a conditioned medium from ETV2-overexpressed ECs (Ad-ETV2 CM) significantly increased VSMC migration. The cytokine array showed altered levels of several cytokines in Ad-ETV2 CM compared with those in normal CM. We found that C-X-C motif chemokine 5 (CXCL5) promoted VSMC migration using the Boyden chamber and wound healing assays. In addition, an inhibitor of C-X-C motif chemokine receptor 2 (CXCR2) (the receptor for CXCL5) significantly inhibited this process. Gelatin zymography showed that the activities of matrix metalloproteinase (MMP)-2 and MMP-9 increased in the media of VSMCs treated with Ad-ETV2 CM. Western blotting revealed a positive correlation between Akt/p38/c-Jun phosphorylation and CXCL5 concentration. The inhibition of Akt and p38-c-Jun effectively blocked CXCL5-induced VSMC migration. In conclusion, CXCL5 from ECs induced by ETV2 promotes VSMC migration via MMP upregulation and the activation of Akt and p38/c-Jun.

Abstract 705: Epha2 Ligand-dependent And Ligand-independent Signaling In Vascular Smooth Muscle Cell Proliferation And Migration

During atherosclerotic plaque formation, vascular smooth muscle cells (VSMCs) undergo phenotypic modulation from a contractile, quiescent phenotype to a proliferative and synthetic phenotype, allowing VSMCs to deposit form a protective fibrous cap to stabilize the cap through extracellular matrix assembly. Our lab discovered a novel role for the receptor tyrosine kinase EphA2 in SMC phenotypic modulation and proliferation both in vitro and in vivo . In many cancer models, EphA2 can act as a tumor promoter in the absence of ligand and a tumor suppressor in the presence of its ephrinA1 ligand. Therefore, we sought to determine the role of ligand-dependent and ligand-independent signaling in VSMC function. While EphA2 expression is required for maximal VSMC proliferation and migration, EphA2 ligation with ephrinA1 inhibits VSMC proliferation (associated with diminished Erk1/2 and Akt activation) and migration. While ligand treatment induces EphA2 tyrosine phosphorylation, treating VSMCs with serum promotes robust S897 phosphorylation (marker for ligand-independent signaling) specifically through RSK2, whereas no role was found for other described S897 kinases (e.g. Akt, RSK1). EphA2 Ser897 phosphorylation specifically localizes to lamellipodia in VSMCs treated with serum, and blocking RSK2-dependent S897 phosphorylation significantly inhibited VSMC migration but did not affect VSMC proliferation. Taken together, these data suggest that VSMC EphA2 ligation suppresses proliferation and migration, whereas RSK2-dependent EphA2 Ser897 phosphorylation in the absence of ligand promotes VSMC migration, and EphA2 expression likely enhances VSMC proliferation through a ligand-independent response independent of S897 phosphorylation.

Chlamydia pneumoniae Infection Induces Vascular Smooth Muscle Cell Migration and Atherosclerosis Through Mitochondrial Reactive Oxygen Species-Mediated JunB-Fra-1 Activation.

Infection is closely related to atherosclerosis, which is a major pathological basis for cardiovascular diseases. Vascular smooth muscle cell (VSMC) migration is an important trigger in development of atherosclerosis that is associated with Chlamydia pneumoniae (C. pneumoniae) infection. However, the mechanism of VSMC migration remains unclear, and whether antioxidant could be a therapeutic target for C. pneumoniae infection-induced atherosclerosis also remains unknown. The results showed that C. pneumoniae infection mainly impaired mitochondrial function and increased the level of mitochondrial reactive oxygen species (mtROS). The expressions of protein JunB, Fra-1 and Matrix metalloproteinase 2 (MMP) evidently increased after C. pneumoniae infection, and the interaction between JunB and Fra-1 was also enhanced. After scavenging mtROS by antioxidant Mito-TEMPO, the increasing expressions of JunB, Fra-1, MMP2 and the capacity of VSMC migration induced by C. pneumoniae infection were all inhibited. In comparison with infected ApoE-/- mice, the level of ROS in atherosclerotic lesion in ApoE-/-TLR2-/- mice with C. pneumoniae infection decreased. Knocking out TLR2 suppressed the expressions of JunB, Fra-1 and MMP2 in VSMCs and the formation of atherosclerotic lesion after C. pneumoniae infection. Furthermore, after using small interfering RNA to inhibit the expression of TLR2, the level of mtROS and the expressions of JunB, Fra-1 and MMP2 apparently decreased. Taken together, C. pneumoniae infection may promote VSMC migration and atherosclerosis development by increasing the level of mtROS through TLR2 to activate the JunB-Fra-1/MMP2 signaling pathway. The data provide the first evidence that antioxidant could reduce C. pneumoniae infection-induced VSMC migration and atherosclerosis.

Platelet-derived microvesicles regulate vascular smooth muscle cell energy metabolism via PRKAA after intimal injury

Vascular intimal injury initiates various cardiovascular disease processes. Exposure to subendothelial collagen can cause platelet activation, leading to collagen-activated platelet-derived microvesicles (aPMVs) secretion. In addition, vascular smooth muscle cells (VSMCs) exposed to large amounts of aPMVs undergo abnormal energy metabolism; they proliferate excessively and migrate after the loss of endothelium, eventually contributing to neointimal hyperplasia. However, the roles of aPMVs in VSMC energy metabolism are still unknown. Our carotid artery intimal injury model indicated that platelets adhered to injured blood vessels. In vitro, phosphorylated Pka (cAMP-dependent protein kinase) content was increased in aPMVs. We also found that aPMVs significantly reduced VSMC glycolysis and increased oxidative phosphorylation, and promoted VSMC migration and proliferation by upregulating phosphorylated PRKAA (α catalytic subunit of AMP-activated protein kinase) and phosphorylated FoxO1. Compound C, an inhibitor of PRKAA, effectively reversed the enhancement of cellular function and energy metabolism triggered by aPMVs in vitro and neointimal formation in vivo. We show that aPMVs can affect VSMC energy metabolism through the Pka-PRKAA-FoxO1 signaling pathway and this ultimately affects VSMC function, indicating that the shift in VSMC metabolic phenotype by aPMVs can be considered a potential target for the inhibition of hyperplasia. This provides a new perspective for regulating the abnormal activity of VSMCs after injury.

MIA SH3 Domain ER Export Factor 3 Deficiency Prevents Neointimal Formation by Restoring BAT-Like PVAT and Decreasing VSMC Proliferation and Migration.

Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) and excessive accumulation of dysfunctional PVAT are hallmarks of pathogenesis after angioplasty. Recent genome-wide association studies reveal that single-nucleotide polymorphism (SNP) in MIA3 is associated with atherosclerosis-relevant VSMC phenotypes. However, the role of MIA3 in the vascular remodeling response to injury remains unknown. Here, we found that expression of MIA3 is increased in proliferative VSMCs and knockdown of MIA3 reduces VSMCs proliferation, migration, and inflammation, whereas MIA3 overexpression promoted VSMC migration and proliferation. Moreover, knockdown of MIA3 ameliorates femoral artery wire injury-induced neointimal hyperplasia and increases brown-like perivascular adipocytes. Collectively, the data suggest that MIA3 deficiency prevents neointimal formation by decreasing VSMC proliferation, migration, and inflammation and maintaining BAT-like perivascular adipocytes in PVAT during injury-induced vascular remodeling, which provide a potential therapeutic target for preventing neointimal hyperplasia in proliferative vascular diseases.

Long non‑coding RNA AL355711 promotes smooth muscle cell migration through the ABCG1/MMP3 pathway.

Atherosclerosis and related cardiovascular diseases pose severe threats to human health worldwide. There is evidence to suggest that at least 50% of foam cells in atheromas are derived from vascular smooth muscle cells (VSMCs); the first step in this process involves migration to human atherosclerotic lesions. Long non-coding RNAs (lncRNAs) have been found to play significant roles in diverse biological processes. The present study aimed to investigate the role of lncRNAs in VSMCs. The expression of lncRNAs or mRNAs was detected using reverse transcription-quantitative polymerase chain reaction. The Gene Expression Omnibus datasets in the NCBI portal were searched using the key words 'Atherosclerosis AND tissue AND Homo sapiens' and the GSE12288 dataset. Gene expression in circulating leukocytes was measured to identify patients with coronary artery disease (CAD) or controls, and used to analyze the correlation coefficient and expression profiles. The protein level of ATP-binding cassette sub-family G member 1 (ABCG1) and matrix metalloproteinase (MMP)3 was determined using immunohistochemistry and western blot analysis. The analysis of mouse aortic roots was performed using Masson's and Oil Red O staining. The expression of lncRNA AL355711, ABCG1 and MMP3 was found to be higher in human atherosclerotic plaques or in patients with atherosclerotic CAD. The correlation analysis revealed that ABCG1 may be involved in the regulation between lncRNA AL355711 and MMP3 in atherosclerotic CAD. The knockdown of lncRNA AL355711 inhibited ABCG1 transcription and smooth muscle cell migration. In addition, lncRNA AL355711 was found to regulate MMP3 expression through the ABCG1 pathway. The expression of ABCG1 and MMP3 was found to be high in an animal model of atherosclerosis. The results indicated that lncRNA AL355711 promoted VSMC migration and atherosclerosis partly via the ABCG1/MMP3 pathway. On the whole, the present study demonstrates that the inhibition of lncRNA AL355711 may serve as a novel therapeutic target for atherosclerosis. lncRNA AL355711 in circulating leukocytes may be a novel biomarker for atherosclerotic CAD.

LINC01123 promotes cell proliferation and migration via regulating miR-1277-5p/KLF5 axis in ox-LDL-induced vascular smooth muscle cells.

The pathophysiological mechanism of carotid atherosclerosis (CAS) involves endothelial cell dysfunction, vascular smooth muscle cells (VSMCs), and macrophage activation, which ultimately leads to fibrosis of the vessel wall. lncRNA works weightily in the formation of CAS, but the function and mechanism of lncRNA LINC01123 in stable plaque formation are still equivocal. We collected blood samples from 35 CAS patients as well as 33 healthy volunteers. VSMCs treated with oxidized low-density lipoprotein (ox-LDL) were utilized as the CAS cell models. We applied qRT-PCR for detecting LINC01123, miR-1277-5p and KLF5 mRNA expression, CCK-8 method and BrdU test for determining cell proliferation, Transwell test for measuring cell migration, as well as Western blot for assaying KLF5 protein expression. Dual-luciferase reporter experiment was adopted for assessing the interaction between LINC01123 and miR-1277-5p, as well as KLF5 and miR-1277-5p. LINC01123 and KLF5 expression were dramatically up-regulated, while miR-1277-5p expression was down-regulated in CAS patients and ox-LDL-induced CAS cell models. Overexpressed LINC01123 notedly promoted VSMCs migration and proliferation. LINC01123 knockdown repressed cell proliferation and migration. Also, LINC01123 targeted miR-1277-5p and down-regulated its expression, while miR-1277-5p could negatively regulate KLF5 expression. LINC01123 is highly expressed in CAS patients, and promotes cell proliferation and migration via regulating miR-1277-5p/KLF5 axis in ox-LDL-induced VSMCs. It might be involved in the fibrous plaque formation.

Neutrophil elastase promotes neointimal hyperplasia by targeting toll-like receptor 4 (TLR4)-NF-κB signalling.

Neointimal hyperplasia (NIH) is the fundamental cause for vascular diseases and vascular smooth muscle cell (VSMC) dysregulation has been widely implicated in NIH. Neutrophil elastase is a potential therapeutic target for multiple diseases. We investigated the role of neutrophil elastase in VSMC functions and injury-induced NIH and explored the therapeutic potential of targeting neutrophil elastase in NIH. VSMCs were used to analyse the effects of neutrophil elastase. Proteomic analysis was used to identify potential neutrophil elastase targets. Artery injury model and neutrophil elastase inhibitor GW311616A were used to investigate the role of neutrophil elastase in NIH. TNF-α up-regulated neutrophil elastase in VSMCs through modulating GAPBα/Runx1/CEBPα/c-Myb signalling. Up-regulated neutrophil elastase promoted VSMC migration, proliferation and inflammation. Toll-like receptor 4 (TLR4) was identified as a target protein for neutrophil elastase in VSMCs and the TLR4/MyD88/IRAK1/TRAF6/NF-κB regulatory axis was shown to be the signalling pathway for neutrophil elastase in VSMC pathology. Importantly, TLR4 inhibition abolished neutrophil elastase-mediated VSMC dysregulation. Injury-induced NIH was significantly reduced in both neutrophil elastase-deficient mice and mice treated with GW311616A. The formation of neutrophil extracellular traps was impaired in injured arteries from neutrophil elastase-deficient mice. Finally, a similar role for neutrophil elastase in human VSMC pathology was confirmed and we observed higher expression levels of neutrophil elastase but lower expression levels of TLR4 in human atherosclerotic lesions. We provide new insight into the molecular mechanisms underlying NIH and identify neutrophil elastase as a potential therapeutic target for vascular disease.

Curcumin-mediated Photodynamic Therapy Inhibits the Phenotypic Transformation, Migration, and Foaming of Oxidized Low-density Lipoprotein-treated Vascular Smooth Muscle Cells by Promoting Autophagy

Vascular smooth muscle cells (VSMCs) are becoming a hot spot and target of atherosclerosis research. This study aimed to observe the specific effects of curcumin (CUR)-mediated photodynamic therapy (CUR-PDT) on oxidized low-density lipoprotein (ox-LDL)-treated VSMCs and confirm whether these effects are mediated by autophagy. In this study, the mouse aortic smooth muscle cell line and A7r5 cell lines were used for parallel experiments. VSMC viability was evaluated by Cell Counting Kit-8 assay. VSMCs were treated with ox-LDL to establish a model of atherosclerosis in vitro. The autophagy level and the expression of proteins related to phenotypic transformation were detected by western blotting. The migration ability of the cells was detected by using transwell assay. The presence of intracellular lipid droplets was detected by Oil Red O staining. The results showed that VSMCs transformed from the contraction phenotype to the synthetic phenotype when stimulated by ox-LDL, during which autophagy was inhibited. However, CUR-PDT treatment significantly promoted the level of autophagy and inhibited the process of phenotypic transformation induced by ox-LDL. In addition, ox-LDL significantly promoted VSMC migration and increased the number of lipid droplets, whereas CUR-PDT treatment significantly reduced the ox-LDL-induced increase in the migration ability of, and lipid droplet numbers in, VSMCs. When the VSMCs were pretreated with the autophagy inhibitor 3-methyladenine for 24 hours, the effects of CUR-PDT were reversed. Therefore, our study indicated that CUR-PDT can inhibit the phenotypic transformation, migration, and foaming of ox-LDL-treated VSMCs by inducing autophagy.

H3K4 Methyltransferase Smyd3 Mediates Vascular Smooth Muscle Cell Proliferation, Migration, and Neointima Formation.

[Figure: see text].

The VWF/LRP4/αVβ3-axis represents a novel pathway regulating proliferation of human vascular smooth muscle cells.

Von Willebrand factor (VWF) is a plasma glycoprotein involved in primary haemostasis, while also having additional roles beyond haemostasis namely in cancer, inflammation, angiogenesis, and potentially in vascular smooth muscle cell (VSMC) proliferation. Here, we addressed how VWF modulates VSMC proliferation and investigated the underlying molecular pathways and the in vivo pathophysiological relevance. VWF induced proliferation of human aortic VSMCs and also promoted VSMC migration. Treatment of cells with a siRNA against αv integrin or the RGT-peptide blocking αvβ3 signalling abolished proliferation. However, VWF did not bind to αvβ3 on VSMCs through its RGD-motif. Rather, we identified the VWF A2 domain as the region mediating binding to the cells. We hypothesized the involvement of a member of the LDL-related receptor protein (LRP) family due to their known ability to act as co-receptors. Using the universal LRP-inhibitor receptor-associated protein, we confirmed LRP-mediated VSMC proliferation. siRNA experiments and confocal fluorescence microscopy identified LRP4 as the VWF-counterreceptor on VSMCs. Also co-localization between αvβ3 and LRP4 was observed via proximity ligation analysis and immuno-precipitation experiments. The pathophysiological relevance of our data was supported by VWF-deficient mice having significantly reduced hyperplasia in carotid artery ligation and artery femoral denudation models. In wild-type mice, infiltration of VWF in intimal regions enriched in proliferating VSMCs was found. Interestingly, also analysis of human atherosclerotic lesions showed abundant VWF accumulation in VSMC-proliferating rich intimal areas. VWF mediates VSMC proliferation through a mechanism involving A2 domain binding to the LRP4 receptor and integrin αvβ3 signalling. Our findings provide new insights into the mechanisms that drive physiological repair and pathological hyperplasia of the arterial vessel wall. In addition, the VWF/LRP4-axis may represent a novel therapeutic target to modulate VSMC proliferation.

Increased AT2R expression is induced by AT1R autoantibody via two axes, Klf-5/IRF-1 and circErbB4/miR-29a-5p, to promote VSMC migration

Vascular remodeling can be caused by angiotensin II type 1 receptor (AT1R) autoantibody (AT1-AA), although the related mechanism remains unknown. Angiotensin II type 2 receptor (AT2R) plays multiple roles in vascular remodeling through cross-talk with AT1R in the cytoplasm. Here, we aimed to explore the role and mechanism of AT2R in AT1-AA-induced vascular smooth muscle cell (VSMC) migration, which is a key event in vascular remodeling. In vitro and in vivo, we found that AT2R can promote VSMC migration in AT1-AA-induced vascular remodeling. Moreover, AT2R expression was upregulated via Klf-5/IRF-1-mediated transcriptional and circErbB4/miR-29a-5p-mediated posttranscriptional mechanisms in response to AT1-AA. Our data provide a molecular basis for AT1-AA-induced AT2R expression by transcription factors, namely, a circular RNA and a microRNA, and showed that AT2R participated in AT1-AA-induced VSMC migration during the development of vascular remodeling. AT2R may be a potential target for the treatment of AT1-AA-induced vascular diseases.

STAT3–CyPA signaling pathway in endothelial cell apoptosis

Cyclophilin A (CyPA), which is encoded by PPIA, is a ubiquitously expressed intracellular protein and is secreted in response to inflammatory stimuli. CyPA stimulates proinflammatory and apoptosis signaling pathways in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), promotes VSMC migration and proliferation, EC adhesion molecules expression, and inflammatory cell chemotaxis and apoptosis. Therefore, we sought to study the transcriptional regulation of CyPA, we hypothesized that transcription factor STAT3 regulated CyPA expression and activated vascular ECs in vitro in a CyPA-dependent manner. Using RT-qPCR, immunostaining, luciferase and ChIP assays, we found that STAT3 induced CyPA expression depended on its transcriptional activation by binding to a specific region containing the STAT3-responsive element (SRE) in the CyPA promoter. Moreover, with cell viability and apoptosis assays, we identified STAT3 stimulated CyPA-dependent apoptosis of human umbilical vein ECs in vitro.

Chlamydia pneumoniae infection promotes vascular smooth muscle cell migration via c-Fos/interleukin-17C signaling

Chlamydia pneumoniae (C. pneumoniae) infection is associated with the initiation and progression of atherosclerosis. The migration of vascular smooth muscle cell (VSMC) from the media to the intima is a key event in the development of atherosclerosis. Interleukin-17C (IL-17C) could enhance cell migration ability. The aim of our study is to investigate the role of IL-17C in C. pneumoniae infection-promoted VSMC migration, thereby possibly accelerating atherosclerosis. We firstly demonstrated that C. pneumoniae infection significantly increased IL-17C expression in VSMCs in the atherosclerotic lesion area from ApoE deficient mice. Our in vitro study further showed that IL-17C is required for C. pneumoniae infection-promoted VSMC migration, and its expression could be regulated by c-Fos through phosphorylating extracellular signal-regulated kinase (ERK). Unexpectedly, in the present study, we also found that IL-17C is critical for C. pneumoniae infection-induced c-Fos activation. c-Fos expression and activation induced by the exposure to recombinant IL-17C were markedly suppressed in the presence of the ERK inhibitor PD98059. These results suggest a possible positive feedback between c-Fos and IL-17C after C. pneumoniae infection. Taken together, our results indicate that C. pneumoniae infection promotes VSMC migration via c-Fos/IL-17C signaling.

Emerging regulators of vascular smooth muscle cell migration

Vascular smooth muscle cells (VSMCs) are the predominant cell type in the blood vessel wall and normally adopt a quiescent, contractile phenotype. VSMC migration is tightly controlled, however, disease associated changes in the soluble and insoluble environment promote VSMC migration. Classically, studies investigating VSMC migration have described the influence of soluble factors. Emerging data has highlighted the importance of insoluble factors, including extracellular matrix stiffness and porosity. In this review, we will recap on the important signalling pathways that regulate VSMC migration and reflect on the potential importance of emerging regulators of VSMC function.

Cyclophilin A–FoxO1 signaling pathway in endothelial cell apoptosis

Cyclophilin A (CyPA), which is encoded by PPIA, is a ubiquitously expressed intracellular protein and is secreted in response to inflammatory stimuli. CyPA stimulates proinflammatory signaling pathways in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), promotes VSMC migration and proliferation, EC adhesion molecules expression, and inflammatory cell chemotaxis and apoptosis. Moreover, CyPA activates mitogen-activated protein kinases, including ERK1/2, JNK, and p38, and stimulates IkB-α phosphorylation, NF-kB activation, and vascular cell adhesion molecule-1 and E-selectin expression in human umbilical vein ECs. Therefore, we hypothesized that CyPA regulated transcription factor FoxO1 phosphorylation and transcriptional activity and the expression of downstream genes involved in vascular EC activation, thus activated vascular ECs in vitro. We found that intracellular CyPA promoted FoxO1 dephosphorylation at Ser256, nuclear accumulation, and transcriptional activity by interacting with it. Moreover, CyPA induced FoxO1-dependent expression of downstream genes involved in EC chemotaxis and apoptosis, including monocyte chemoattractant protein-1 and BCL-2-interacting mediator of cell death, and stimulated the apoptosis of human umbilical vein ECs in vitro.

Exosomes from nicotine-stimulated macrophages accelerate atherosclerosis through miR-21-3p/PTEN-mediated VSMC migration and proliferation.

Rationale: During the development of atherosclerosis, macrophages secrete exosomes that regulate vascular smooth muscle cells (VSMCs); however, whether nicotine, a major constituent of cigarettes, can modulate this communication in the context of atherogenesis remains to be further studied. In this study, we hypothesized that nicotine induces macrophages to secrete atherogenic exosomes containing microRNAs (miRNAs) to mediate cell-to-cell crosstalk and encourage proatherogenic phenotypes of VSMCs.Methods: In an in vivo study, nicotine was administered subcutaneously to 8-week-old male ApoE-/- mice fed a high-fat diet (HFD) for 12 weeks. Oil red O and hematoxylin and eosin (HE) were used to stain atherosclerotic lesions. Lesion macrophages, VSMCs and exosomes were stained for CD68, α-smooth muscle actin (α-SMA) and CD9, and plaque exosomes were observed by transmission electron microscopy (TEM). Exosomes derived from control macrophages (M-Exos) and from nicotine-treated macrophages (NM-Exos) were isolated by ultracentrifugation, purified by sucrose density gradient centrifugation and characterized based on specific morphology and surface markers. The IVIS® Spectrum in vivo imaging system showed the biodistribution of NM-Exos and M-Exos in circulation. Chitosan hydrogel-incorporated exosomes were applied to simulate exosome secretion in situ. Scratch wound assay, transwell assay and EdU staining were conducted to assess the effects of NM-Exos on the migration and proliferation of mouse VSMCs. RNA-seq was performed to determine the miRNA profiles of M-Exos and NM-Exos. Quantitative real-time PCR (qRT-PCR) analysis was conducted to detect the expression levels of miRNAs and mRNAs. The roles of the candidate miRNA and its target gene were assessed using specific RNA inhibitors, siRNAs and miRNA mimics. Western blotting was used to detect candidate protein expression levels. A dual-luciferase reporting system was utilized to confirm the binding of a specific miRNA to its target gene.Results: Nicotine induced atherosclerotic lesion progression and resulted in plaque exosome retention in vivo. The biodistribution of NM-Exos showed that plaque-resident exosomes might be secreted in situ. VSMCs cocultured in vitro with nicotine-stimulated macrophages presented an increased capacity for migration and proliferation, which was exosome-dependent. In addition, isolated NM-Exos helped promote VSMC migration and proliferation. miRNA profiling showed that miR-21-3p was enriched in NM-Exos, and this miRNA was shown to play a key role in regulating NM-Exos-induced effects by directly targeting phosphatase and tension homologue (PTEN).Conclusion: Exosomal miR-21-3p from nicotine-treated macrophages may accelerate the development of atherosclerosis by increasing VSMC migration and proliferation through its target PTEN.