Impaired phosphorylation of ACE2 Ser680 by AMPK in pulmonary endothelium leads to a labile ACE2 and hence is associated with the pathogenesis of PH. Thus, AMPK regulation of the vasoprotective ACE2 is a potential target for PH treatment.
Rationale Endothelial-to-mesenchymal transition (EndoMT) is implicated in myofibroblast-like cell-mediated damage to the coronary arterial wall in acute Kawasaki disease (KD) patients, as evidenced by positive staining for connective tissue growth factor (CTGF) and EndoMT markers in KD autopsy tissues. However, little is known about the molecular basis of EndoMT involved in KD. Objective We investigated the microRNA (miRNA) regulation of CTGF and the consequent EndoMT in KD pathogenesis. As well, the modulation of this process by statin therapy was studied. Methods and Results Sera from healthy children and KD subjects were incubated with human umbilical vein endothelial cells (HUVECs). Cardiovascular disease-related miRNAs, CTGF, and EndoMT markers were quantified using RT-qPCR, ELISA, and Western blotting. Compared to healthy controls, HUVEC incubated with sera from acute KD patients had decreased miR-483, increased CTGF, and increased EndoMT markers. Bioinformatics analysis followed by functional validation demonstrated that Krüppel-like factor 4 (KLF4) transactivates miR-483, which in turn targets the 3′ untranslated region of CTGF mRNA. Overexpression of KLF4 or pre-miR-483 suppressed, whereas knockdown of KLF4 or anti-miR-483 enhanced, CTGF expression in ECs in vitro and in vivo. Furthermore, atorvastatin, currently being tested in a Phase I/IIa clinical trial in KD children, induced KLF4-miR-483, which suppressed CTGF and EndoMT in ECs. Conclusions KD sera suppress the KLF4-miR-483 axis in ECs leading to increased expression of CTGF and induction of EndoMT. This detrimental process in the endothelium may contribute to coronary artery abnormalities in KD patients. Statin therapy may benefit acute KD patients, in part through the restoration of KLF4-miR-483 expression. Clinical Trial Registration NCT01431105
Background Atherosclerosis is a multifaceted inflammatory disease involving cells in the vascular wall [e.g., endothelial cells (ECs)] as well as circulating and resident immunogenic cells (e.g., monocytes/macrophages). Acting as a ligand for liver X receptor (LXR), but an inhibitor of sterol regulatory element binding protein 2 (SREBP2), 25-hydroxycholesterol (25-HC) and its catalyzing enzyme cholesterol-25-hydroxylase (Ch25h) are important in regulating cellular inflammatory status and cholesterol biosynthesis in both ECs and monocytes/macrophages. Methods Bioinformatic analyses were used to investigate RNA-seq data to identify cholesterol oxidation and efflux genes regulated by KLF4. In vitro experiments involving cultured ECs and macrophages and in vivo methods involving mice with Ch25h ablation were then used to explore the atheroprotective role of KLF4-Ch25h/LXR. Results Vasoprotective stimuli increased the expression of Ch25h and LXR via krüppel-like factor 4 (KLF4). The KLF4-Ch25h/LXR homeostatic axis functions through suppressing inflammation, evidenced by the reduction of inflammasome activity in ECs and the promotion of M1 to M2 phenotypic transition in macrophages. The increased atherosclerosis in ApoE−/−/Ch25h−/− mice further demonstrates the beneficial role of the KLF4-Ch25h/LXR axis in vascular function and disease. Conclusions KLF4 transactivates Ch25h and LXR thereby promoting the synergistic effects between ECs and macrophages to protect against atherosclerosis susceptibility.
The epsin family of endocytic adapter proteins are widely expressed, and interact with both proteins and lipids to regulate a variety of cell functions. However, the role of epsins in atherosclerosis is poorly understood. Here, we show that deletion of endothelial epsin proteins reduces inflammation and attenuates atherosclerosis using both cell culture and mouse models of this disease. In atherogenic cholesterol-treated murine aortic endothelial cells, epsins interact with the ubiquitinated endoplasmic reticulum protein inositol 1,4,5-trisphosphate receptor type 1 (IP3R1), which triggers proteasomal degradation of this calcium release channel. Epsins potentiate its degradation via this interaction. Genetic reduction of endothelial IP3R1 accelerates atherosclerosis, whereas deletion of endothelial epsins stabilizes IP3R1 and mitigates inflammation. Reduction of IP3R1 in epsin-deficient mice restores atherosclerotic progression. Taken together, epsin-mediated degradation of IP3R1 represents a previously undiscovered biological role for epsin proteins and may provide new therapeutic targets for the treatment of atherosclerosis and other diseases.
Toll-like receptor-mediated NF-κB activation is a major innate immune reaction of vascular endothelial cells (ECs) in response to prooxidative and proinflammatory stimuli. We identified that TNF-α receptor-associated factor-interacting protein with a forkhead-associated domain (TIFA) is a regulator of priming (signal 1) and activating (signal 2) signals of nucleotide oligomerization domain-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome in ECs. Oxidative and inflammatory stresses such as atheroprone flow and hyperlipidemia induce and activate TIFA in vitro and in vivo. For the priming of signal 1, sterol regulatory element-binding protein 2 transactivates TIFA, which in turn induces NF-κB activation and augments the transcription of NLRP3 inflammasome components. For the activation of signal 2, Akt is involved in TIFA Thr9 phosphorylation, which is essential for TIFA-TIFA homophilic oligomerization. Thr9 phosphorylation-dependent TIFA oligomerization facilitates the higher-order assembly of NLRP3 inflammasome, as indicated by the interaction between TIFA and caspase-1 in the activated ECs. Our results suggest that TIFA is a crucial mediator in the endothelial innate immune response by potentiating and amplifying NLRP3 inflammasome via augmenting signals 1 and 2.endothelial cells | inflammasome | innate immunity | NLRP3 | TIFA
Triptolide is a key anti-inflammatory compound of the Chinese herbal medicine Tripterygium wilfordii Hook. f. (Celastraceae). It also possesses potent antitumor activity. In this study, we show that triptolide is an angiogenesis inhibitor based on various angiogenesis assays. The IC 50 in in vitro assays was 45 nM, which was much lower than the plasma concentrations of triptolide in the rat or human administered with T. wilfordii extracts for treating inflammation. When dosed in vivo, triptolide potently inhibited angiogenesis at 100 nM in Matrigel plug assay. Triptolide at 0.75 mg/kg/day significantly blocked tumor angiogenesis and tumor progression in murine tumorigenesis assay. The underlying mechanism of triptolide correlated with downregulation of proangiogenic Tie2 and VEGFR-2 expression in human umbilical vein endothelial cell by semiquantitative RT-PCR and western blot analysis. Although Tie2 inhibition appeared to be a later event as compared with VEGFR-2, Tie2 overexpression significantly attenuated the inhibitory effect of triptolide on endothelial proliferation and network formation. By contrast, Tie2 knockdown mimicked the inhibitory effect of triptolide on endothelial network formation. Our findings suggest that antitumor action of triptolide is partly via inhibition of tumor angiogenesis by blocking 2 endothelial receptormediated signaling pathways, and triptolide can be a promising antiangiogenic agent.Tripterygium wilfordii Hook. f. (Celastraceae), also known as Thunder God Vine, is a popular herb in China for the treatment of immune-inflammatory diseases including rheumatoid arthritis, systemic lupus erythematosus, nephritis and asthma. 1 Extracts from T. wilfordii has entered clinical trials for the treatment of rheumatoid arthritis. 2-5 Characterization of the active components present in this plant identified triptolide, a diterpenoid triepoxide, as a key component responsible for most of the immunosuppressive, anti-inflammatory and antiproliferative effects. 6 The content of triptolide was thus used as the quality control marker for most of the extracts and preparations made from T. wilfordii. 7-9 Triptolide itself has also been tested in clinical trials for the treatment of psoriasis vulgaris, 10 diabetic nephropathy 11 and nephritic syndrome 12 in China.Triptolide was first found to have antileukemic activity in 1972. 13 In addition to its potent immunosuppressive and antiinflammatory activities, its antitumor activity has attracted much interest since then. Triptolide exerted antiproliferative and proapoptotic effects on tumor cell lines in vitro, 14-16 restricted tumor growth or shrank tumor in vivo. 17,18 Furthermore, triptolide sensitized tumor cells to other anticancer agents 19 and had synergistic effect with other chemotherapeutic agents in preclinical animal models. 15,18 Although tumor growth and metastasis depend upon angiogenesis, there are only preliminary studies on the effect of triptolide on angiogenesis. 20,21 Antiangiogenic therapy has been increasingly recognized as a pr...
Objective— The topographical distribution of atherosclerosis in vasculature underscores the importance of shear stress in regulating endothelium. With a systems approach integrating sequencing data, the current study aims to explore the link between shear stress-regulated master transcription factor and its regulation of endothelial cell (EC) function via epigenetic modifications. Approach and Results— H3K27ac (acetylation of histone 3 lysine 27)-ChIP-seq (chromatin immunoprecipitation followed by high throughput sequencing), ATAC-seq (an assay for transposase-accessible chromatin-sequencing), and RNA-seq (RNA-sequencing) were performed to investigate the genome-wide epigenetic regulations in ECs in response to atheroprotective pulsatile shear stress (PS). In silico prediction revealed that KLF4 binding motifs were enriched in the PS-enhanced H3K27ac regions. By integrating PS- and KLF4-modulated H3K27ac, we identified 18 novel PS-upregulated genes. The promoter regions of these genes showed an overlap between the KLF4-enhanced assay for transposase-accessible chromatin signals and the PS-induced H3K27ac peaks. Experiments using ECs isolated from mouse aorta, lung ECs from EC-KLF4-TG versus EC-KLF4-KO mice, and atorvastatin-treated ECs showed that ITPR3 (inositol 1,4,5-trisphosphate receptor 3) was robustly activated by KLF4 and statins. KLF4 ATAC-qPCR (quantitative polymerase chain reaction) and ChIP-qPCR further demonstrated that a specific locus in the promoter region of the ITPR3 gene was essential for KLF4 binding, H3K27ac enrichment, chromatin accessibility, RNA polymerase II recruitment, and ITPR3 transcriptional activation. Deletion of this KLF4 binding locus in ECs by using CRISPR-Cas9 resulted in blunted calcium influx, reduced expression of endothelial nitric oxide synthase, and diminished nitric oxide bioavailability. Conclusions— These results from a novel multiomics study suggest that KLF4 is crucial for PS-modulated H3K27ac that allow the transcriptional activation of ITPR3. This novel mechanism contributes to the Ca 2+ -dependent eNOS (endothelial nitric oxide synthase) activation and EC homeostasis.
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