Browsing by Author "Chen, Zhen"

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AMP-activated Protein Kinase Phosphorylation of Angiotensin-Converting Enzyme 2 in Endothelium Mitigates Pulmonary Hypertension
(2018-08-15)
Zhang, Jiao
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Dong, Jianjie
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Martin, Marcy
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He, Ming
;
Gongol, Brendan
Rationale: Endothelial dysfunction plays an integral role in pulmonary hypertension (PH). AMPK (AMP-activated protein kinase) and ACE2 (angiotensin-converting enzyme 2) are crucial in endothelial homeostasis. The mechanism by which AMPK regulates ACE2 in the pulmonary endothelium and its protective role in PH remain elusive. Objectives: We investigated the role of AMPK phosphorylation of ACE2 Ser680 in ACE2 stability and deciphered the functional consequences of this post-translational modification of ACE2 in endothelial homeostasis and PH. Methods: Bioinformatics prediction, kinase assay, and antibody against phospho-ACE2 Ser680 (p-ACE2 S680) were used to investigate AMPK phosphorylation of ACE2 Ser680 in endothelial cells. Using CRISPR-Cas9 genomic editing, we created gain-of-function ACE2 S680D knock-in and loss-of-function ACE2 knockout (ACE22/2) mouse lines to address the involvement of p-ACE2 S680 and ACE2 in PH. The AMPK-p-ACE2 S680 axis was also validated in lung tissue from humans with idiopathic pulmonary arterial hypertension. Measurements and Main Results: Phosphorylation of ACE2 by AMPK enhanced the stability of ACE2, which increased Ang (angiotensin) 1-7 and endothelial nitric oxide synthase-derived NO bioavailability. ACE2 S680D knock-in mice were resistant to PH as compared with wild-type littermates. In contrast, ACE2-knockout mice exacerbated PH, a similar phenotype found in mice with endothelial cell-specific deletion of AMPK alpha 2. Consistently, the concentrations of phosphorylated AMPK, p-ACE2 S680, and ACE2 were decreased in human lungs with idiopathic pulmonary arterial hypertension. Conclusions: 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.
Atheroprotective Flow Upregulates ITPR3 (Inositol 1,4,5-Trisphosphate Receptor 3) in Vascular Endothelium via KLF4 (Kruppel-Like Factor 4)-Mediated Histone Modifications
(2019-05-01)
He, Ming
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Huang, Tse-Shun
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Li, Shuai
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Hong, Hsiao-Chin
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Chen, Zhen
Objective-The topographical distribution of atherosclerosis in vasculature underscores the importance of shear stress inregulating 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 RNAseq (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 Ca2+-dependent eNOS (endothelial nitric oxide synthase) activation and EC homeostasis.
Deep Sequencing and Bioinformatics Analysis of Endothelial MicroRNA under Hypoxia Stress
(2010-04-01)
Chen, Zhen
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Sun, Wei
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Padmanabhan, Chellappan
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Wang, Wei-Chi
;
Jin, Hailing
Hypoxia-responsive miRNAs target argonaute 1 to promote angiogenesis
(2013-03-01)
Chen, Zhen
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Lai, Tsung-Ching
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Jan, Yi-Hua
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Lin, Feng-Mao
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Wang, Wei-Chi
Despite a general repression of translation under hypoxia, cells selectively upregulate a set of hypoxia-inducible genes. Results from deep sequencing revealed that Let-7 and miR-103/107 are hypoxia-responsive microRNAs (HRMs) that are strongly induced in vascular endothelial cells. In silico bioinformatics and in vitro validation showed that these HRMs are induced by HIF1 alpha and target argonaute 1 (AGO1), which anchors the microRNA-induced silencing complex (miRISC). HRM targeting of AGO1 resulted in the translational desuppression of VEGF mRNA. Inhibition of HRM or overexpression of AGO1 without the 3' untranslated region decreased hypoxia-induced angiogenesis. Conversely, AGO1 knockdown increased angiogenesis under normoxia in vivo. In addition, data from tumor xenografts and human cancer specimens indicate that AGO1-mediated translational desuppression of VEGF may be associated with tumor angiogenesis and poor prognosis. These fmdings provide evidence for an angiogenic pathway involving HRMs that target AGO1 and suggest that this pathway may be a suitable target for anti- or proangiogenesis strategies.
MicroRNA-92a Mediates Endothelial Dysfunction in CKD
(2017-11-01)
Shang, Fenqing
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Wang, Shen-Chih
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Hsu, Chien-Yi
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Miao, Yifei
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Martin, Marcy
CKD is an independent risk factor for cardiovascular disease (CVD). The accumulation of uremic toxins in CKD induces oxidative stress and endothelial dysfunction. MicroRNA-92a (miR-92a) is induced by oxidative stress in endothelial cells (ECs) and involved in angiogenesis and atherosclerosis. We investigated a role for oxidative stress responsive miR-92a in CKD. Our study of patients at three clinical sites showed increased serum miR-92a level with decreased kidney function. In cultured ECs, human CKD serum or uremic toxins (such as indoxyl sulfate), compared with non-CKD serum, induced the levels of miR-92a and suppressed the expression of miR-92a targets, including key endothelial-protective molecules. The antioxidant N-acetylcysteine inhibited these vasculopathic properties. In rats, adenine-induced CKD associated with increased levels of miR-92a in aortas, serum, and CD144(+) endothelial microparticles. Furthermore, CD144(+) microparticles from human uremic serum contained more miR-92a than those from control serum. Additional analysis showed a positive correlation between serum levels of miR-92a and indoxyl sulfate in a cohort of patients with ESRD undergoing hemodialysis. Collectively, our findings suggest that the uremic toxins accumulated in CKD can upregulate miR-92a in ECs, which impairs EC function and predisposes patients to CVD.
miR-103/107 Promote Metastasis of Colorectal Cancer by Targeting the Metastasis Suppressors DAPK and KLF4
(2012-07-15)
Chen, Hsin-Yi
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Lin, Yu-Min
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Chung, Hsiang-Ching
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Lang, Yaw-Dong
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Lin, Ching-Jung
Metastasis is the major cause of poor prognosis in colorectal cancer (CRC), and increasing evidence supports the contribution of miRNAs to cancer progression. Here, we found that high expression of miR-103 and miR-107 (miR-103/107) was associated with metastasis potential of CRC cell lines and poor prognosis in patients with CRC. We showed that miR-103/107 targeted the known metastasis suppressors death-associated protein kinase (DAPK) and Kruppel-like factor 4 (KLF4) in CRC cells, resulting in increased cell motility and cell-matrix adhesion and decreased cell-cell adhesion and epithelial marker expression. miR-103/107 expression was increased in the presence of hypoxia, thereby potentiating DAPK and KLF4 downregulation and hypoxia-induced motility and invasiveness. In mouse models of CRC, miR-103/107 overexpression potentiated local invasion and liver metastasis effects, which were suppressed by reexpression of DAPK or KLF4. miR-103/107-mediated downregulation of DAPK and KLF4 also enabled the colonization of CRC cells at a metastatic site. Clinically, the signature of a miR-103/107 high, DAPK low, and KLF4 low expression profile correlated with the extent of lymph node and distant metastasis in patients with CRC and served as a prognostic marker for metastasis recurrence and poor survival. Our findings therefore indicate that miR-103/107-mediated repression of DAPK and KLF4 promotes metastasis in CRC, and this regulatory circuit may contribute in part to hypoxia-stimulated tumormetastasis. Strategies that disrupt this regulation might be developed to block CRC metastasis. Cancer Res; 72(14); 3631-41. (c) 2012 AACR.
Oxidative Stress Activates Endothelial Innate Immunity via Sterol Regulatory Element Binding Protein 2 (SREBP2) Transactivation of MicroRNA-92a
(2015-03-03)
Chen, Zhen
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Wen, Liang
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Martin, Marcy
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Hsu, Chien-Yi
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Fang, Longhou
Background-Oxidative stress activates endothelial innate immunity and disrupts endothelial functions, including endothelial nitric oxide synthase-derived nitric oxide bioavailability. Here, we postulated that oxidative stress induces sterol regulatory element-binding protein 2 (SREBP2) and microRNA-92a (miR-92a), which in turn activate endothelial innate immune response, leading to dysfunctional endothelium. Methods and Results-Using cultured endothelial cells challenged by diverse oxidative stresses, hypercholesterolemic zebrafish, and angiotensin II-infused or aged mice, we demonstrated that SREBP2 transactivation of microRNA-92a (miR-92a) is oxidative stress inducible. The SREBP2-induced miR-92a targets key molecules in endothelial homeostasis, including sirtuin 1, Kruppel-like factor 2, and Kruppel-like factor 4, leading to NOD-like receptor family pyrin domain-containing 3 inflammasome activation and endothelial nitric oxide synthase inhibition. In endothelial cell-specific SREBP2 transgenic mice, locked nucleic acid-modified antisense miR-92a attenuates inflammasome, improves vasodilation, and ameliorates angiotensin II-induced and aging-related atherogenesis. In patients with coronary artery disease, the level of circulating miR-92a is inversely correlated with endothelial cell-dependent, flow-mediated vasodilation and is positively correlated with serum level of interleukin-1 beta. Conclusions-Our findings suggest that SREBP2-miR-92a-inflammasome exacerbates endothelial dysfunction during oxidative stress. Identification of this mechanism may help in the diagnosis or treatment of disorders associated with oxidative stress, innate immune activation, and endothelial dysfunction.
Sterol Regulatory Element Binding Protein 2 Activation of NLRP3 Inflammasome in Endothelium Mediates Hemodynamic-Induced Atherosclerosis Susceptibility
(2013-08-06)
Xiao, Han
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Lu, Min
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Lin, Ting Yang
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Chen, Zhen
;
Chen, Gang
Background-The molecular basis for the focal nature of atherosclerotic lesions is poorly understood. Here, we explored whether disturbed flow patterns activate an innate immune response to form the NLRP3 inflammasome scaffold in vascular endothelial cells via sterol regulatory element binding protein 2 (SREBP2). Methods and Results-Oscillatory flow activates SREBP2 and induces NLRP3 inflammasome in endothelial cells. The underlying mechanisms involve SREBP2 transactivating NADPH oxidase 2 and NLRP3. Consistently, SREBP2, NADPH oxidase 2, and NLRP3 levels were elevated in atheroprone areas of mouse aortas, suggesting that the SREBP2-activated NLRP3 inflammasome causes functionally disturbed endothelium with increased inflammation. Mimicking the effect of atheroprone flow, endothelial cell-specific overexpression of the activated form of SREBP2 synergized with hyperlipidemia to increase atherosclerosis in the atheroresistant areas of mouse aortas. Conclusions-Atheroprone flow induces NLRP3 inflammasome in endothelium through SREBP2 activation. This increased innate immunity in endothelium synergizes with hyperlipidemia to cause topographical distribution of atherosclerotic lesions.