Smooth Muscle Cell Differentiation Marker Research Articles

Importance of smooth muscle p110alpha/AKT/FOXO1 signaling for the development of abdominal aortic aneurysm

Abstract Background Abdominal aortic aneurysms (AAA) are characterized by loss of vascular smooth muscle cells (SMCs) and extracellular matrix (ECM) degradation. The catalytic PI 3-kinase isoform p110α signals downstream of growth factor receptors. Mice harboring an SMC-specific p110α deficiency (SM-p110α-/-) are characterized by impaired SMC proliferation and survival. Aim We hypothesized that p110α deficiency in SMCs exacerbates the development and progression of AAA as it promotes SMC loss and thus weakens the aortic wall in healthy and diseased animals. Therefore, we investigated how p110α deficiency in SMCs affects AAA formation, vascular integrity as well as downstream signaling in SMCs. Methods and results Medial thickness of the abdominal aorta in SM-p110α-/- mice was significantly decreased compared to wild-type (WT) littermate controls (29.0±3.1µm vs. 42.5±4.1µm). Morphological characterization of the aortic wall by transmission electron microscopy revealed impaired elastic fibers, detached SMCs and apoptotic cells in SM-p110α-/- mice. SMC differentiation markers including calponin and myosin heavy chain were downregulated in the aortic wall of SM-p110α-/- mice. Western blots demonstrated that p110α deficiency impaired the expression of elastin. Consequently, elastin fibers were characterized by reduced fiber width and length. In addition, growth factor stimulated proliferation of p110α-/- SMCs was significantly impaired compared to WT controls. AAA development in SM-p110α-/- mice and WT littermates were studied using the porcine pancreatic elastase (PPE) model. PPE was infused into the infrarenal aorta. Ultrasound examination of the aorta revealed an increased aortic diameter in all PPE-treated mice. However, the increase in aortic diameter was significantly elevated (p<0.05) in SM-p110α-/- mice (70.2±10.8%, n=9) compared to WT animals (42.4±6.0%, n=10). Furthermore, PPE treated SM-p110-/- mice were characterized by increased ECM degradation, decreased vascular remodelling, and less proliferating cells. Mechanistically, growth factor-dependent phosphorylation and inactivation of crucial phenotypic modulators of SMCs - FOXO-1, -3 and -4 - were shown to be significantly decreased in p110α-/- SMCs compared to WT cells. Specific inhibition of FOXO1 rescued the impaired proliferation of p110α-/- SMCs and enhanced the expression of elastin and calponin. Analysis of FOXO expression in humans revealed that FOXO1 was significantly upregulated in AAA patients compared to healthy individuals. Conclusion p110α deficiency in SMCs promotes the development and progression of AAA, as p110α controls crucial SMC functions which are important for structural processes in the aortic wall. Thereby, SMC proliferation is controlled by p110α dependent phosphorylation and inactivation of FOXO1. Since FOXO1 is upregulated in AAA patients, the p110α/AKT/FOXO1 signaling cascade may provide a key target for modulating aortic wall stability in AAA.

Insights into clinical diagnosis and treatment of malignant hepatic perivascular epithelioid cell tumor.

Perivascular epithelioid cell tumors (PEComas) are infrequent mesenchymal tumors. They are usually benign, and only a few are malignant. These tumors are more commonly found in middle-aged women. PEComas are mainly composed of differentiated perivascular epithelioid cells arranged radially around the vascular cavity, and they are usually positive for melanocyte markers and smooth muscle cell differentiation markers. Among the PEComas, hepatic PEComas generally have no obvious symptoms and no typical imaging manifestations. Malignant hepatic PEComas are even rarer. So, we explained our insights into clinical diagnosis and treatment of malignant hepatic PEComas, in order to help clinicians and pathologists to further understand PEComas.

MiR-16-5p Is a Novel Mediator of Venous Smooth Muscle Phenotypic Switching

Vein graft failure after coronary artery bypass grafting (CABG) is primarily caused by intimal hyperplasia, which results from the phenotypic switching of venous smooth muscle cells (SMCs). This study investigates the role and underlying mechanism of miR-16-5p in the phenotypic switching of venous SMCs. In rats, neointimal thickness and area increased over time within 28 days after CABG, as did the time-dependent miR-16-5p downregulation and SMC phenotypic switching. Platelet-derived growth factor-BB-induced miR-16-5p downregulation in HSVSMCs was accompanied by and substantially linked with alterations in phenotypic switching indicators. Furthermore, miR-16-5p overexpression increased SMCs differentiation marker expression while suppressing HSVSMCs proliferation and migration and drastically inhibiting neointimal development in vein grafts. The miR-16-5p inhibited zyxin expression, which was necessary for HSVSMCs phenotypic switching. The miR-16-5p/zyxin axis is a novel, potentially therapeutic target for preventing and treating venous graft intimal hyperplasia.Graphical abstract

β‐catenin C‐terminal Domain/Sphingosine‐1‐Phosphate Receptor 1 Axis is a Potential Therapeutic Target in Vascular Remodeling

Vascular smooth muscle cells (SMCs), in part via activation of the Wnt/β‐catenin signaling pathway, contribute importantly to vascular remodeling. While the C‐terminal domain of β‐catenin links the pathway to gene expression, how this domain and related molecular mechanisms are involved in vascular remodeling is unknown. Inhibitors targeting specifically the C‐terminal domain of β‐catenin have been developed, but their use in obstructive vascular disease is not yet justified because of this gap of knowledge. Our group has previously shown that β‐catenin C‐terminal domain in SMCs is essential for arterial wall assembly during embryogenesis, but its role in vascular remodeling in adulthood is unknown. Therefore, the objective of this study was to define the importance of β‐catenin C‐terminal domain in SMCs during vascular remodeling and the underlying molecular mechanisms.To test the hypothesis that β‐catenin C‐terminal domain in SMCs is required for vascular remodeling, mice bearing a mutant β‐catenin allele (ΔC) that prevents the transcription of the C‐terminal domain were crossed with the SMC‐specific SMA‐CreERT2 line to generate mice bearing one β‐catenin flox allele and one knockin mutant (Ctnnb1ΔC/flox) or wt (Ctnnb1wt/flox) allele. In this system, tamoxifen administration removes the flox allele, resulting in mice bearing the mutant allele (SMβCΔC mice) or the wt allele (SMβCwt/‐ mice) as the only sources of β‐catenin in SMCs. To induce vascular remodeling, we performed carotid artery ligation one week after tamoxifen injection in male and female adult mice. Carotid arteries from both male and female SMβCΔC mice showed reduced neointima formation after injury induced by ligation compared to SMβCwt/‐ mice. Arteries from SMβCΔC mice also showed reduced SMC proliferation and increased SMC apoptosis and differentiation markers. We also isolated mouse aortic SMCs (MASMCs) from Ctnnb1ΔC/flox mice, and transduced these cells with GFP‐ or Cre‐expressing adenovirus to obtain control (βCControl) or cells expressing β‐cateninΔC(βCΔC) and found that βCΔC MASMCs show reduced growth compared to βCControl. To gain further insight on the mechanisms underlying the effects of β‐catenin C‐terminus, we performed whole‐transcriptome analysis by RNA‐seq of βCΔC and βCControl MASMCs and found a downregulation of the sphingosine‐1‐phosphate receptor 1 (S1pr1) gene in βCΔC MASMCs. This receptor is known to be important in vascular remodeling, but its regulation is not fully elucidated. Interestingly, we found decreased S1PR1 expression in SMCs of injured arteries from SMβC∆C mice. Consistent with this observation, βCΔC MASMCs showed reduced S1PR1 mRNA and protein levels and decreased S1pr1 promoter activity, which were all rescued by the transfection of a constitutively active form of β‐catenin. By using a S1PR1lox/stop/lox conditional gain‐of‐function mouse line, we found that overexpression of S1PR1 in SMCs rescues the injury‐induced neointima formation in SMβC∆C mice. Consistently, overexpression of S1PR1 in SMCs restored βCΔC MASMC growth towards βCControl levels. Taken together, our results define an essential SMC β‐catenin C‐terminal domain–S1PR1 axis that drives neointima formation after arterial injury, and identify multiple points for potential therapeutic intervention to control vascular remodeling in disease.

RGC-32′ dual role in smooth muscle cells and atherogenesis

Proliferation of endothelial cells (EC) and smooth muscle cells (SMC) is a critical process in atherosclerosis. Here, we investigated the involvement of sublytic C5b-9 effector Response Gene to Complement 32 (RGC-32) in cell cycle activation, phenotypic switch, and production of extracellular matrix (ECM) in SMC. Overexpression of RGC-32 augmented C5b-9-induced cell cycle activation and proliferation of SMC in an ERK1-dependent manner and silencing of RGC-32 inhibited C5b-9-induced cell cycle activation. C5b-9-induced cell cycle activation also required phosphorylation of RGC-32 at threonine 91. We found that ECM components fibronectin and collagens I-V were expressed by SMC in human aortic atherosclerotic tissue. Silencing of RGC-32 in cultured SMC was followed by a significant reduction in TGF-β-induced expression of SMC differentiation markers myocardin, SM22 and α-SMA, and that of collagens I, IV and V. These data suggest that RGC-32 participates in both sublytic C5b-9-induced cell cycle activation and TGF-β-induced ECM production.

Construction and Evaluation of Recombinant Chimeric Fibrillin and Elastin Fragment in Human Mesenchymal Stem Cells.

Diverse extracellular matrix (ECM) proteins physically interact with stem cells and regulate stem cell function. However, the large molecular weight of the natural ECM renders large-scale fabrication of a similar functional structure challenging. The objective of this study was to construct a low molecular weight and multifunctional chimeric form of recombinant ECM to stimulate mesenchymal stem cell (MSC) for tissue repair. We engineered Fibrillin-1PF14 fused to an elastin-like polypeptide to develop a new biomimetic ECM for stem cell differentiation and investigated whether this recombinant chimeric Fibrillin-Elastin fragment (rcFE) was effective on human nasal inferior turbinate-derived mesenchymal stem cells (hTMSCs). hTMSCs were grown in the medium supplemented with rcFE, then the effect of the protein was confirmed through cell adhesion assay, proliferation assay, and real-time PCR. rcFE enhanced the adhesion activity of hTMSCs by 2.7-fold at the optimal concentration, and the proliferation activity was 2.6-fold higher than that of the control group (non-treatment rcFE). In addition, when smooth muscle cell differentiation markers were identified by real-time PCR, Calponin increased about 6-fold, α-actin about 9-fold, and MYH11 about 10-fold compared to the control group. Chimeric rcFE enhanced cellular functions such as cell adhesion, proliferation, and smooth muscle differentiation of hTMSCs, suggesting that the rcFE can facilitate the induction of tissue regeneration.

Andrographolide Promotes Interaction Between Endothelin-Dependent EDNRA/EDNRB and Myocardin-SRF to Regulate Pathological Vascular Remodeling.

IntroductionPathological vascular remodeling is a hallmark of various vascular diseases. Smooth muscle cell (SMC) phenotypic switching plays a pivotal role during pathological vascular remodeling. The mechanism of how to regulate SMC phenotypic switching still needs to be defined. This study aims to investigate the effect of Andrographolide, a key principle isolated from Andrographis paniculate, on pathological vascular remodeling and its underlying mechanism.MethodsA C57/BL6 mouse left carotid artery complete ligation model and rat SMCs were used to determine whether Andrographolide is critical in regulating SMC phenotypic switching. Quantitative real-time PCR, a CCK8 cell proliferation assay, BRDU incorporation assay, Boyden chamber migration assay, and spheroid sprouting assay were performed to evaluate whether Andrographolide suppresses SMC proliferation and migration. Immunohistochemistry staining, immunofluorescence staining, and protein co-immunoprecipitation were used to observe the interaction between EDNRA, EDNRB, and Myocardin-SRF.ResultsAndrographolide inhibits neointimal hyperplasia in the left carotid artery complete ligation model. Andrographolide regulates SMC phenotypic switching characterized by suppressing proliferation and migration. Andrographolide activates the endothelin signaling pathway exhibited by dramatically inducing EDNRA and EDNRB expression. The interaction between EDNRA/EDNRB and Myocardin-SRF resulted in promoting SMC differentiation marker gene expression.ConclusionAndrographolide plays a critical role in regulating pathological vascular remodeling.

Spheroids of Bladder Smooth Muscle Cells for Bladder Tissue Engineering

Cell-based tissue engineering (TE) has been proposed to improve treatment outcomes in end-stage bladder disease, but TE approaches with 2D smooth muscle cell (SMC) culture have so far been unsuccessful. Here, we report the development of primary bladder-derived 3D SMC spheroids that outperform 2D SMC cultures in differentiation, maturation, and extracellular matrix (ECM) production. Bladder SMC spheroids were compared with 2D cultures using live-dead staining, qRT-PCR, immunofluorescence, and immunoblotting to investigate culture conditions, contractile phenotype, and ECM deposition. The SMC spheroids were viable for up to 14 days and differentiated rather than proliferating. Spheroids predominantly expressed the late myogenic differentiation marker MyH11, whereas 2D SMC expressed more of the general SMC differentiation marker α-SMA and less MyH11. Furthermore, the expression of bladder wall-specific ECM proteins in SMC spheroids was markedly higher. This first establishment and analysis of primary bladder SMC spheroids are particularly promising for TE because differentiated SMCs and ECM deposition are a prerequisite to building a functional bladder wall substitute. We were able to confirm that SMC spheroids are promising building blocks for studying detrusor regeneration in detail and may provide improved function and regenerative potential, contributing to taking bladder TE a significant step forward.

Controlled Growth Factor Delivery and Cyclic Stretch Induces a Smooth Muscle Cell-like Phenotype in Adipose-Derived Stem Cells

Adipose-derived stem cells (ASCs) are an abundant and easily accessible multipotent stem cell source with potential application in smooth muscle regeneration strategies. In 3D collagen hydrogels, we investigated whether sustained release of growth factors (GF) PDGF-AB and TGF-β1 from GF-loaded microspheres could induce a smooth muscle cell (SMC) phenotype in ASCs, and if the addition of uniaxial cyclic stretch could enhance the differentiation level. This study demonstrated that the combination of cyclic stretch and GF release over time from loaded microspheres potentiated the differentiation of ASCs, as quantified by protein expression of early to late SMC differentiation markers (SMA, TGLN and smooth muscle MHC). The delivery of GFs via microspheres produced large ASCs with a spindle-shaped, elongated SMC-like morphology. Cyclic strain produced the largest, longest, and most spindle-shaped cells regardless of the presence or absence of growth factors or the growth factor delivery method. Protein expression and cell morphology data confirmed that the sustained release of GFs from GF-loaded microspheres can be used to promote the differentiation of ASCs into SMCs and that the addition of uniaxial cyclic stretch significantly enhances the differentiation level, as quantified by intermediate and late SMC markers and a SMC-like elongated cell morphology.

On the biocompatibility of graphene oxide towards vascular smooth muscle cells

Graphene and its derivatives have shown fascinating potential in biomedical applications. However, the biocompatibility of graphene with vascular smooth muscle cells (VSMCs) and applications to vascular engineering have not been explored extensively. Using a rat aortic smooth muscle cell line, A7r5, as a VSMC model, we have explored the effects of graphene oxide (GO) on the growth and behaviours of VSMCs. Results demonstrated that GO had no obvious toxicity to VSMCs. Cells cultured on GO retained the expression of smooth muscle cell-specific markers CNN1, ACTA2 and SMTN, on both mRNA and protein levels. A wound healing assay demonstrated no effect of GO on cell migration. We also found that small-flaked GO favoured the proliferation of VSMCs, suggesting a potential of using surface chemistry or physical properties of GO to influence cell growth behaviour. These results provide insight into the suitability of GO as a scaffold for vascular tissue engineering.

Zinc Inhibits HIF-Prolyl Hydroxylase Inhibitor-Aggravated VSMC Calcification Induced by High Phosphate.

Vascular calcification is a life-threatening clinical condition in chronic kidney disease (CKD) and is associated with reduced zinc serum levels. Anemia is another frequent complication of CKD. Hypoxia-inducible factor (HIF) stabilizers, also known as HIF prolyl hydroxylase inhibitors (PHI), are promising candidates to treat CKD-associated anemia by increasing erythropoietin synthesis. Recent evidence suggests that HIFs play a pivotal role in vascular calcification. Our study explored feasible impacts of HIF PHI on phosphate (Pi)-induced calcification of vascular smooth muscle cells (VSMCs) and tested whether zinc might inhibit this mineralization process. Treatment of VSMCs with PHI aggravated Pi-induced calcium deposition and Pi uptake. PHI promoted Pi-induced loss of smooth muscle cell markers (ACTA-2, MYH11, SM22α) and enhanced osteochondrogenic gene expression (Msx-2, BMP-2, Sp7) triggering osteochondrogenic phenotypic switch of VSMCs. These effects of PHI paralleled with increased pyruvate dehydrogenase kinase 4 (PDK4) expression, decreased Runx2 Ser451 phosphorylation, and reduced cell viability. Zinc inhibited Pi-induced mineralization of VSMCs in a dose-dependent manner and also attenuated the pro-calcification effect of PHI in Pi-induced mineralization. Zinc inhibited osteochondrogenic phenotypic switch of VSMCs reflected by lowering Pi uptake, decreasing the expressions of Msx-2, BMP-2, and Sp7 as well as the loss of smooth muscle cell-specific markers. Zinc preserved phosphorylation state of Runx2 Ser451, decreased PDK4 level, and restored cell viability. PHI alone reduced the expression of smooth muscle markers without inducing mineralization, which was also inhibited by zinc. In addition, we observed a significantly lower serum zinc level in CKD as well as in patients undergoing carotid endarterectomy compared to healthy individuals. Conclusion - PHI promoted the loss of smooth muscle markers and augmented Pi-induced osteochondrogenic phenotypic switch leading to VSMCs calcification. This mineralization process was attenuated by zinc. Enhanced vascular calcification is a potential risk factor during PHI therapy in CKD which necessitates the strict follow up of vascular calcification and zinc supplementation.

Vanadium Derivative Exposure Promotes Functional Alterations of VSMCs and Consequent Atherosclerosis via ROS/p38/NF-κB-Mediated IL-6 Production.

Vanadium is a transition metal widely distributed in the Earth’s crust, and is a major contaminant in fossil fuels. Its pathological effect and regulation in atherosclerosis remain unclear. We found that intranasal administration of the vanadium derivative NaVO3 significantly increased plasma and urinary vanadium levels and induced arterial lipid accumulation and atherosclerotic lesions in apolipoprotein E-deficient knockout mice (ApoE−/−) murine aorta compared to those in vehicle-exposed mice. This was accompanied by an increase in plasma reactive oxygen species (ROS) and interleukin 6 (IL-6) levels and a decrease in the vascular smooth muscle cell (VSMC) differentiation marker protein SM22α in the atherosclerotic lesions. Furthermore, exposure to NaVO3 or VOSO4 induced cytosolic ROS generation and IL-6 production in VSMCs and promoted VSMC synthetic differentiation, migration, and proliferation. The anti-oxidant N-acetylcysteine (NAC) not only suppresses IL-6 production and VSMC pathological responses including migration and proliferation but also prevents atherosclerosis in ApoE−/− mice. Inhibition experiments with NAC and pharmacological inhibitors demonstrated that NaVO3-induced IL-6 production is signaled by ROS-triggered p38-mediated NF-κB-dependent pathways. Neutralizing anti-IL-6 antibodies impaired NaVO3-mediated VSMC migration and proliferation. We concluded that NaVO3 exposure activates the ROS-triggering p38 signaling to selectively induce NF-κB-mediated IL-6 production. These signaling pathways induce VSMC synthetic differentiation, migration, and proliferation, leading to lipid accumulation and atherosclerosis.

Abstract 107: Smooth Muscle α-actin Translocates to the Nucleus and Participates in Chromatin Remodeling at Smooth Muscle Contractile Gene Promoters

Smooth muscle cell specific α-actin (SMA, encoded by ACTA2 ), like other actins, polymerizes in the cytoplasm to form actin filaments that slide along smooth muscle myosin filaments to enact smooth muscle cell (SMC) contraction. Ubiquitously expressed β-actin polymerizes in filaments in the cytoplasm and also enters the nucleus and associates with various chromatin remodeling complexes. Nuclear β-actin has been shown to be important for the differentiation of a number of cell types, including neurons. We therefore asked whether SMA translocates to the nucleus and if nuclear SMA is critical for differentiation of smooth muscle cells. In explanted SMCs from human and mouse ascending aortas, cell fractionation and 2D gel electrophoresis identifies both SMA and β-actin in the nuclear isolates. Nuclear SMA but not β-actin accumulates with SMC differentiation driven by serum starvation and transforming growth factor β1 (TGFβ1) treatment. Chromatin immunoprecipitation with an SMA antibody reveals that the protein is bound to the promoters of SMC differentiation marker genes, including Acta2 , Cnn1, and Myh11 and that SMA is enriched over β-actin at these promoters with differentiation. Immunoprecipitation studies show that SMA binds specifically to the INO80 and the SWI/SNF chromatin remodeling complexes. In Acta2 -/- mouse SMCs, skeletal muscle α-actin (SKA) is ectopically expressed to compensate for the loss of SMA; SKA is in the nucleus and is enriched after TGFβ1 treatment, associating with both the INO80 and SWI/SNF complexes. Acta2 -/- SMCs are completely differentiated and respond normally to TGFβ1. However, in the mouse myoblast cell line C2C12, SKA is present in nuclear fractions but does not enrich with differentiation of these cells into myotubes, and is not associated with INO80 or SWI/SNF. We therefore propose that nuclear SMA is required for the remodeling of chromatin during the differentiation of SMCs, allowing contractile genes to become accessible for transcription, and that this remodeling is mediated by the involvement of SMA in the INO80 and SWI/SNF complexes These findings describe a novel role for SMA in the nucleus.

Sphingosine 1-phosphate induces epicardial progenitor cell differentiation into smooth muscle-like cells.

Epicardial progenitor cells (EpiCs) which are derived from the proepicardium have the potential to differentiate into coronary vascular smooth muscle cells during development. Whether sphingosine 1-phosphate (S1P), a highly hydrophobic zwitterionic lysophospholipid in signal transduction, induces the differentiation of EpiCs is unknown. In the present study, we demonstrated that S1P significantly induced the expression of smooth muscle cell specific markers α-smooth muscle actin and myosin heavy chain 11 in the EpiCs. And the smooth muscle cells differentiated from the EpiCs stimulated by S1P were further evaluated by gel contraction assay. To further confirm the major subtype of sphingosine 1-phosphate receptors (S1PRs) involved in the differentiation of EpiCs, we used the agonists and antagonists of different S1PRs. The results showed that the S1P1/S1P3 antagonist VPC23019 and the S1P2 antagonist JTE013 significantly attenuated EpiCs differentiation, while the S1P1 agonist SEW2871 and antagonist W146 did not affect EpiCs differentiation. These results collectively suggested that S1P, principally through its receptor S1P3, increases EpiCs differentiation into VSMCs and thus indicated the importance of S1P signaling in the embryonic coronary vasculature, while S1P2 plays a secondary role.

Temporal and spatial changes of peroxiredoxin 2 levels in aortic media at very early stages of atherosclerotic lesion formation in apoE-knockout mice

The events that trigger early onset of atherosclerotic lesion formation are poorly understood. Initially, microscopic atherosclerotic lesions appear in the aortic root in 10-week-old apoE-knockout mice that are fed normal chow. Using proteome and immunohistochemical analyses, we investigated proteins in aortic media whose expression changes in athero-prone regions at the beginning of lesion formation. Protein profiles of the root/arch and thoracic/abdominal regions of aortas in 10-week-old apoE-knockout mice were analyzed using 2D-gel electrophoresis. Proteins in 81 spots with different abundance were identified. Among them, we focused on proteins related to oxidative stress and smooth muscle cells (SMCs). The level of peroxiredoxin 2 (Prx2), a major cellular antioxidant enzyme that reduces hydrogen peroxide, was lower in aortic root/arch compared with thoracic/abdominal aorta. Immunohistochemical staining demonstrated that Prx2 expression in SMCs in the aortic root was high at 4 weeks and decreased at 10 weeks in apoE-knockout mice, while Prx2 expression in the aorta was unchanged in wild-type mice. The level of Prx2 expression correlated positively with the SMC differentiation markers, α-smooth muscle actin and transgelin, suggesting that a decline in Prx2 expression accompanies SMC dedifferentiation. Accumulated acrolein-modified proteins and the infiltration of macrophages in aortic media were observed in areas with low Prx2 expression. These results showed that Prx2 expression declines in athero-prone aortic root before lesion formation, and this reduction in Prx2 expression correlates with lipid peroxidation, SMC dedifferentiation, and macrophage recruitment.

NF-κB inhibits the differentiation of hysteromyoma cells by reducing myocardin expression.

To investigate the effect of nuclear factor-kappaB (NF-κB) on the myocardin-mediated differentiation of hysteromyoma cells. Expression levels of myocardin in hysteromyoma cells from patients with hysteromyoma were detected. Normal uterine smooth muscle cells were used as control group. Overexpression of myocardin in hysteromyoma cells was achieved through lentivirus infection. Changes in expression levels of uterine smooth muscle cell maker p21, p57, Cyclin D1, PCNA, SM22α, and αSMA were detected. Hysteromyoma cells with lentivirus infection were stimulated by lipopolysaccharide (LPS), and changes in expression levels of myocardin were detected. Compared with normal uterine smooth muscle cells, the expression level of myocardin in hysteromyoma cells was extremely low, or even undetectable, and expression levels of smooth muscle cell differentiation markers were also minimal, and cells were in the de-differentiated state. Expression of exogenous myocardin can improve the expression of smooth muscle cell differentiation markers to induce cell re-differentiation. LPS stimulation can activate NF-κB to inhibit myocardin expression, thereby inducing cell dedifferentiation. NF-κB can inhibit the differentiation of hysteromyoma cells by decreasing the expression level of myocardin.

Phenotypic characterization of adenomyosis occurring at the inner and outer myometrium.

ObjectiveTo estimate the phenotypic characterization of fibrotic process in adenomyosis occurring at the inner or the outer myometrium.MethodsEight cases of adenomyosis occurring at the inner myometrium (Subtype I) and 10 cases of adenomyosis occurring at the outer myometrium (Subtype II), and 10 normal counterparts were used in this study. A immunohistochemical study for smooth muscle cells (SMCs) was performed using cytoskeletal proteins, Type I and III collagen, TGF-β and its signaling molecules.ResultsAn increased expression of Type I collagen was observed in the extracellular matrix of adenomyotic foci. In normal uteri, immunostaining of SMC differentiation marker proteins (Desmin, Smoothelin, Myosin heavy chain (MHC)) were absent or only found in low numbers at the inner myometrium, while all of these marker proteins were clearly stained at the outer myometrium. In both types of adenomyotic foci, Desmin, Smoothelin, and MHC commonly showed a negative staining at the adjacent area to the glands. A significant staining of Non-muscle myosin IIB, TGF-β, and phosphorylated TGF-β type I receptors were found only at the SMCs of Subtype II adenomyosis. The Smad3/2 ratio of Subtype II adenomyosis was significantly higher than that of Subtype I.ConclusionsThe inner myometrium of normal uteri was composed of undifferentiated phenotypes of SMCs, while the outer myometrium was composed of terminally differentiated SMCs. Various fibrotic processes have been suggested in the development of uterine adenomyosis. Distinct expression patterns of fibrosis related proteins have been shown to be implicated with differences in the subtypes of adenomyosis.

VEGF-A Stimulates STAT3 Activity via Nitrosylation of Myocardin to Regulate the Expression of Vascular Smooth Muscle Cell Differentiation Markers

Vascular endothelial growth factor A (VEGF-A) is a pivotal player in angiogenesis. It is capable of influencing such cellular processes as tubulogenesis and vascular smooth muscle cell (VSMC) proliferation, yet very little is known about the actual signaling events that mediate VEGF-A induced VSMC phenotypic switch. In this report, we describe the identification of an intricate VEGF-A-induced signaling cascade that involves VEGFR2, STAT3, and Myocardin. We demonstrate that VEGF-A promotes VSMC proliferation via VEGFR2/STAT3-mediated upregulating the proliferation of markers like Cyclin D1 and PCNA. Specifically, VEGF-A leads to nitrosylation of Myocardin, weakens its effect on promoting the expression of contractile markers and is unable to inhibit the activation of STAT3. These observations reinforce the importance of nitric oxide and S-nitrosylation in angiogenesis and provide a mechanistic pathway for VEGF-A-induced VSMC phenotypic switch. In addition, Myocardin, GSNOR and GSNO can create a negative feedback loop to regulate the VSMC phenotypic switch. Thus, the discovery of this interactive network of signaling pathways provides novel and unexpected therapeutic targets for angiogenesis-dependent diseases.

Activation of the cell membrane angiotensin AT2 receptors in human leiomyosarcoma cells induces differentiation and apoptosis by a PPARγ - dependent mechanism.

Angiotensin II (Ang II), the main effector peptide of the renin-angiotensin system (RAS), acting on AT1 and AT2 receptors participates in the regulation of proliferation, differentiation and apoptosis in tumour cells. The peroxisome-proliferator activated receptor γ (PPARγ) and its ligands exert anti-tumour effects in various human cancer cell lines. The present study investigates the effects initiated by AT1- and AT2 receptor stimulation in SK-UT-1 cells, a human leiomyosarcoma cell line, and clarifies the role of the PPARγ in the AT2 receptor-induced differentiation and apoptosis.Selective stimulation of AT1- and AT2 receptors was achieved by incubation of the cells with Ang II (10-6 M) in the presence of the selective AT2 receptor antagonist, PD 123177 (10-6 M) and the AT1 receptor antagonist, losartan (10-5 M), respectively, the selective PPARγ antagonist, GW 9662, was used at concentration 10-6 M. The expression of smooth muscle cell differentiation markers, SM22α and calponin, was analysed at RNA- and protein levels using RT PCR and Western blot, which was also used to quantify Bcl-2-, Bax- and cleaved caspase-3 proteins. The translocation of the AT2-receptor interacting protein 1 (ATIP1) to the nuclei was studied by Western blot and immunofluorescence staining. The mitochondrial status and the metabolic activity in response to AT1- and AT2 receptor activation were assessed by the quantification of 99mTc - sestamibi and 2´-deoxy-2´-[18F]fluoro-D-glucose uptake.AT1 receptor stimulation did not exert any profound effects in quiescent SK-UT-1 cells. The effects induced by Ang II acting on AT2 receptors were time-dependent. A short, 3 - 6 h lasting stimulation promotes differentiation, i.e increases in the mRNA- and protein levels of SM22α and calponin, whereas a sustained stimulation for 48 h activates the intrinsic apoptotic pathway, as evidenced by reduced cell numbers, down-regulation of the anti-apoptotic Bcl-2 protein and increased levels of the Bax protein and cleaved caspase-3. The effects were reversed by the PPARγ antagonist, GW 9662, clearly implying a PPARγ-dependent mechanism. Our results also demonstrate a co-localisation of the AT2-receptor interacting protein, ATIP1, and the PPARγ in nuclei of SK-UT-1 cells and an accumulation of ATIP1 in the nuclear fraction in response to AT2 receptor stimulation. The regulation of the differentiation and apoptosis via the AT2 receptor favours an important functional role of this receptor in quiescent, slow-cycling SK-UT-1 cells and provides the rationale for the use of AT1 receptor antagonists for the treatment of human leiomyosarcomas.

Abstract 409: Notch Signaling in Bone Marrow-derived FSP-1 + Cells Mediates a Phenotypic Change in Smooth Muscle Cells Leading to AVF Failure

Background: sociological and economic costs of failed arteriovenous fistulas (AVF) are well known but mechanisms of AVF losses are controversial. We have shown that smooth muscle cells (SMCs) from anastomosed artery compose of ~50% of neointima cells in AVF. Arterial anastomoses are also infiltrated by bone marrow (BM)-derived FSP-1 + cells, potentially linking FSP-1 + cells to SMC activation. However, whether Notch/RBP-JK signaling involves in BM-derived FSP-1 + cells activation has not been studied. We propose that Notch/RBP-JK activation in BM-derived FSP-1 + cells causes a phenotype-switch of SMCs, resulting in SMC translocation from the artery to the venous anastomosis, forming neointima. Methods: we created CKD and AVFs in wild type and Notch knock out mice. The role of Notch signaling in activation and function of BM-derived FSP-1 + cells was explored. Activated SMCs were characterized by a loss of differentiation markers plus a gain in proliferation (PCNA+). Using BM transplantation, we examined if FSP-1 + cells lacking RBP-JK in CKD mice would suppress SMC phenotype switch and neointima formation in AVFs. Results: BM-derived FSP-1 + inflammatory cells in AVFs from CKD mice were 45% greater vs. results in pair-fed, control mice. In the artery anastomosis, increased infiltration of FSP-1 + cells led to loss of SMC differentiation markers, SMMHC, SM-22 and SMA-α. Activation of Notch signaling (N1ICD + and RBP-JK + ) raised expression of cytokines (IL-1β, MCP-1) and growth factors (PDGF-BB, bFGF2 and TGF-β1) in FSP-1 + cells, The cytokines and growth factors caused a SMC phenotype switch (characterized by loss of SMC markers), resulting in SMC migration and proliferation. RBP-JK KO in BM-derived FSP-1 + cells significantly decreased the production of cytokines and growth factors, suppressed SMC activation of and neointima formation in AVFs. Conclusions: Notch signaling in BM-derived FSP-1 + cells can induce a phenotypic switch in SMCs stimulating neointima growth. Targeting Notch signaling in FSP-1 + cells could improve AFV function.