Enhancer of Zeste Homolog 2 Induces Pulmonary Artery Smooth Muscle Cell Proliferation

Pulmonary Arterial Hypertension (PAH) is a progressively devastating disease characterized by excessive proliferation of the Pulmonary Arterial Smooth Muscle Cells (PASMCs). Studies suggest that PAH and cancers share an apoptosis-resistant state featuring excessive cell proliferation. The proliferation of cancer cells is mediated by increased expression of Enhancer of Zeste Homolog 2 (EZH2), a mammalian histone methyltransferase that contributes to the epigenetic silencing of target genes. However, the role of EZH2 in PAH has not been studied. In this study, it is hypothesized that EZH2 could play a role in the proliferation of PASMCs.In the present study, the expression patterns of EZH2 were investigated in normal and hypertensive mouse PASMCs. The effects of EZH2 overexpression on the proliferation of human PASMCs were tested. PASMCs were transfected with EZH2 or GFP using nucleofector system. After transfection, the cells were incubated for 48 hours at 37°C. Proliferation and cell cycle analysis were performed using flow cytometry. Apoptosis of PASMCs was determined using annexin V staining and cell migration was tested by wound healing assay.EZH2 protein expression in mouse PASMCs were correlated with an increase in right ventricular systolic pressure and Right Ventricular Hypertrophy (RVH). The overexpression of EZH2 in human PASMCs enhances proliferation, migration, and decrease in the rate of apoptosis when compared to GFP-transfected cells. In the G2/M phase of the EZH2 transfected cells, there was a 3.5 fold increase in proliferation, while there was a significant decrease in the rate of apoptosis of PASMCs, when compared to control.These findings suggest that EZH2 plays a role in the migration and proliferation of PASMCs, which is a major hallmark in PAH. It also suggests that EZH2 could play a role in the development of PAH and can serve as a potential target for new therapies for PAH

Similarity-based web clip matching

The research areas of extraction and integration of web data aim at delivery of tools and methods to extract pieces of information from third-party web sites and then to integrate them into profiled, domain-specific, custom web pages. Existing solutions rely on specialized APIs or XPath querying tools and are therefore not easily accessible to non technical end users. In this paper we describe our new comprehensive, non-XPath integration platform which allows end users to extract web page fragments using a simple query-by-example approach and then to combine these fragments into custom, integrated web pages. We focus on our two novel similarity-based web clip matching algorithms: Attribute Weights Tree Matching and Edit Distance Tree Matching

Atherogenesis and plaque rupture, surface/interface-related phenomena

In atherogenesis, free oxygen radicals cause a lipid peroxidation of apoB100-containing lipoproteins in the blood, at the blood–endothelium-interface and in the subendothelial space. These lipoproteins easily aggregate, bind to their receptor heparan sulfate proteoglycan and calcify to arteriosclerotic nanoplaques (ternary complexes). Nanoplaque formation was measured by ellipsometry, both in vitro on an HS-PG coated hydrophobic silica surface and also in vivo on living human coronary endothelial cells, which had overgrown the silica surface. Reversely, we show with the same techniques that, in dependence on the degree of peroxidation and epitope in concern, oxLDL attacks its molecular receptor and thus can induce degradation of arteriosclerotic plaques and, in a combined action with inflammatory processes, even a plaque rupture. In order to delay or stop this process, cytokines circulating in the blood such as TNFα and TGFβ upregulate PML-NB especially in the vulnerable shoulder region of the plaque. PML-NB influences via two transcription factors, CIITA and NFκB, the collagen and proteoglycan synthesis both negatively and positively. We could prove that the purely negative effect of CIITA does not play any role, while the altogether positive effect of NFκB predominates. NFκB is inhibited with the help of the transcription mediator SMAD4 within this molecular feedback control circuit; simultaneously, NFκB inhibits the collagen and proteoglycan synthesis in the fibrous cap of the plaque. This double check (disinhibition) causes a stabilization of the fibrous cap through a specially strong collagen and proteoglycan production, which in addition is supported by circulating TGFβ. TGFβ furthers also calcification, so that fibrous cap tensile strength and resistance to shear stress are imparted. This way, a plaque rupture can possibly be averted

Morphometry of skeletal muscle capillaries: the relationship between capillary ultrastructure and ageing in humans.

AIM To determine whether the ultrastructure of the capillary system in human skeletal muscle changes during advancing senescence, we evaluated the compartmental and subcompartmental organization of capillaries from vastus lateralis muscle (VL) biopsies of 41 non-diseased persons aged 23-75 years. METHODS From each VL biopsy, 38-40 randomly selected capillaries were assessed by transmission electron microscopy and subsequent morphometry with a newly established tablet-based image analysis technique. RESULTS Quantification of the compartmental organization revealed most indicators of the capillary ultrastructure to be only non-significantly altered (P > 0.05) over age. However, the peri-capillary basement membrane (BM) was thicker in the older participants than in the younger ones (P ≤ 0.05). Regression analysis revealed a bipartite relationship between the two parameters: a homogenous slight increase in BM thickness up to the age of approximately 50 years was followed by a second phase with more scattered BM thickness values. In 44.5% of the capillary profiles, projections/filopodia of the pericytes (PCs) traversed the BM and invaded endothelial cells (ECs) visible as PC pegs in pale cytoplasm holes (EC sockets). Strikingly, PC pegs were often in proximity to the EC nucleus. In PC profiles, sockets were likewise detected in 14.2% of the capillaries. Within these PC sockets, cellular profiles were frequently seen, which could be assigned to EC filopodia, internal PC curling or PC-PC interactions. Quantification of the occurrence of peg-socket junctions revealed the proportions of empty EC sockets and empty PC sockets to increase (P ≤ 0.05) during ageing. CONCLUSION Our investigation demonstrates advancing senescence to be associated with increase in BM thickness and loss of EC and PC filopodia length in skeletal muscle capillaries

Dysregulation of the IL-13 receptor system: A novel pathomechanism in pulmonary arterial hypertension.

RATIONALE: Idiopathic pulmonary arterial hypertension (IPAH) is characterized by medial hypertrophy due to pulmonary artery smooth muscle cell (paSMC) hyperplasia. Inflammation is proposed to play a role in vessel remodeling associated with IPAH. IL-13 is emerging as a regulator of tissue remodeling; however, the contribution of the IL-13 system to IPAH has not been assessed. OBJECTIVES: The objective of this study was to assess the possible contribution of the IL-13 system to IPAH. METHODS: Expression and localization of IL-13, and IL-13 receptors IL-4R, IL-13Rα1, and IL-13Rα2 were assessed by real-time reverse transcription-polymerase chain reaction, immunohistochemistry, and flow cytometry in lung tissue, paSMC, and microdissected vascular lesions from patients with IPAH, and in lung tissue from rodents with hypoxia- or monocrotaline-induced pulmonary hypertension. A whole-genome microarray analysis was used to study IL-13-regulated genes in paSMC. MEASUREMENTS AND MAIN RESULTS: Pulmonary expression of the IL-13 decoy receptor IL-13Rα2 was up-regulated relative to that of the IL-13 signaling receptors IL-4R and IL-13Rα1 in patients with IPAH and in two animal models of IPAH. IL-13, signaling via STAT3 and STAT6, suppressed proliferation of paSMC by promoting G(0)/G(1) arrest. Whole-genome microarrays revealed that IL-13 suppressed endothelin-1 production by paSMC, suggesting that IL-13 controlled paSMC growth by regulating endothelin production. Ectopic expression of the il13ra2 gene resulted in partial loss of paSMC growth control by IL-13 and blunted IL-13 suppression of endothelin-1 production by paSMC, whereas small-interfering RNA knockdown of il13ra2 gene expression had the opposite effects. CONCLUSIONS: The IL-13 system is a novel regulator of paSMC growth. Dysregulation of IL-13 receptor expression in IPAH may partially underlie smooth muscle hypertrophy associated with pathological vascular remodeling in IPAH

Dysregulation of the IL-13 receptor system: a novel pathomechanism in pulmonary arterial hypertension

RATIONALE: Idiopathic pulmonary arterial hypertension (IPAH) is characterized by medial hypertrophy due to pulmonary artery smooth muscle cell (paSMC) hyperplasia. Inflammation is proposed to play a role in vessel remodeling associated with IPAH. IL-13 is emerging as a regulator of tissue remodeling; however, the contribution of the IL-13 system to IPAH has not been assessed. OBJECTIVES: The objective of this study was to assess the possible contribution of the IL-13 system to IPAH. METHODS: Expression and localization of IL-13, and IL-13 receptors IL-4R, IL-13Ralpha1, and IL-13Ralpha2 were assessed by real-time reverse transcription-polymerase chain reaction, immunohistochemistry, and flow cytometry in lung tissue, paSMC, and microdissected vascular lesions from patients with IPAH, and in lung tissue from rodents with hypoxia- or monocrotaline-induced pulmonary hypertension. A whole-genome microarray analysis was used to study IL-13-regulated genes in paSMC. MEASUREMENTS AND MAIN RESULTS: Pulmonary expression of the IL-13 decoy receptor IL-13Ralpha2 was up-regulated relative to that of the IL-13 signaling receptors IL-4R and IL-13Ralpha1 in patients with IPAH and in two animal models of IPAH. IL-13, signaling via STAT3 and STAT6, suppressed proliferation of paSMC by promoting G(0)/G(1) arrest. Whole-genome microarrays revealed that IL-13 suppressed endothelin-1 production by paSMC, suggesting that IL-13 controlled paSMC growth by regulating endothelin production. Ectopic expression of the il13ra2 gene resulted in partial loss of paSMC growth control by IL-13 and blunted IL-13 suppression of endothelin-1 production by paSMC, whereas small-interfering RNA knockdown of il13ra2 gene expression had the opposite effects. CONCLUSIONS: The IL-13 system is a novel regulator of paSMC growth. Dysregulation of IL-13 receptor expression in IPAH may partially underlie smooth muscle hypertrophy associated with pathological vascular remodeling in IPAH