Publications by authors named "Ji Youn Youn"

30 Publications

  • Page 1 of 1

Toll-like Receptor 2 (TLR2) Deficiency Abrogates Diabetic and Obese Phenotypes while Restoring Endothelial Function via Inhibition of NOX1.

Diabetes 2021 Jun 14. Epub 2021 Jun 14.

Division of Molecular Medicine, Department of Anesthesiology, Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095;

We have previously demonstrated a novel role of bone morphogenic protein-4 (BMP4) in inducing NOX1-dependent eNOS uncoupling, endothelial dysfunction, and inflammatory activation in type 2 diabetes mellitus (T2DM). However, it has remained unclear as to how BMP4 activates NOX1 and whether targeting the new mechanistic pathway revealed is effective in preserving endothelial function in T2DM. Here we observed that BMP4 induced marked, time-dependent increase in physiological binding between TLR2 and NOX1 in aortic endothelial cells, as well as increased binding of TLR2 to NOXO1. In high-fat diet fed (TLR2 knockout) mice, the body weight gain was significantly less compared to WT (wild-type) mice both in males and females. The high-fat diet induced increases in fasting blood glucose levels, as well as in circulating insulin and leptin levels, were absent in mice. High-fat feeding induced increases in overall fat mass, and fat mass of different pockets were abrogated in mice. Whereas energy intake was similar in high-fat fed WT and mice, TLR2 deficiency resulted in higher energy expenditure attributed to improved physical activity, which was accompanied by restored skeletal muscle mitochondrial function. In addition, TLR2 deficiency recoupled eNOS, reduced total superoxide production, improved HB and NO bioavailabilities in aortas and restored endothelium-dependent vasorelaxation. Collectively, our data strongly indicate that TLR2 plays important roles in the development of metabolic features of T2DM, and its related endothelial/vascular dysfunction. Therefore, targeting TLR2 may represent a novel therapeutic strategy for T2DM, obesity and cardiovascular complications via specific inhibition of NOX1.
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http://dx.doi.org/10.2337/db20-0591DOI Listing
June 2021

Traditional Chinese Medicine (TCM) in the treatment of COVID-19 and other viral infections: Efficacies and mechanisms.

Pharmacol Ther 2021 09 31;225:107843. Epub 2021 Mar 31.

Department of Anesthesiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, United States of America. Electronic address:

COVID-19 has remained an uncontained, worldwide pandemic. While battling for the disease in China, six Traditional Chinese Medicine (TCM) recipes have been shown to be remarkably effective for treating patients with COVID-19. The present review discusses principles of TCM in curing infectious disease, and clinical evidence and mechanisms of the 6 most effective TCM recipes used in treating COVID-19 in 92% of all of the confirmed cases in China. Applications of TCM and specific recipes in the treatment of other viral infections, such as those caused by SARS-CoV, MERS-CoV, hepatitis B virus, hepatitis C virus, influenza A virus (including H1N1 and H7N9), influenza B, dengue virus as well as Ebola virus, are also discussed. Among the 6 TCM recipes, Jinhua Qinggan (JHQG) granules and Lianhua Qingwen (LHQW) capsules are recommended during medical observation; Lung Cleansing and Detoxifying Decoction (LCDD) is recommended for the treatment of both severe and non-severe patients; Xuanfeibaidu (XFBD) granules are recommended for treating moderate cases; while Huashibaidu (HSBD) and Xuebijing (XBJ) have been used in managing severe cases effectively. The common components and the active ingredients of the six TCM recipes have been summarized to reveal most promising drug candidates. The potential molecular mechanisms of the active ingredients in the six TCM recipes that target ACE2, 3CL and IL-6, revealed by molecular biological studies and/or network pharmacology prediction/molecular docking analysis/visualization analysis, are fully discussed. Therefore, further investigation of these TCM recipes may be of high translational value in enabling novel targeted therapies for COVID-19, potentially via purification and characterization of the active ingredients in the effective TCM recipes.
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http://dx.doi.org/10.1016/j.pharmthera.2021.107843DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8011334PMC
September 2021

Targeting MDM2 for Neuroblastoma Therapy: In Vitro and In Vivo Anticancer Activity and Mechanism of Action.

Cancers (Basel) 2020 Dec 5;12(12). Epub 2020 Dec 5.

Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, USA.

Background: Neuroblastoma is an aggressive pediatric solid tumor with an overall survival rate of <50% for patients with high-risk disease. The majority (>98%) of pathologically-diagnosed neuroblastomas have wild-type p53 with intact functional activity. However, the mouse double minute 2 (MDM2) homolog, an E3 ubiquitin ligase, is overexpressed in neuroblastoma and leads to inhibition of p53. MDM2 also exerts p53-independent oncogenic functions. Thus, MDM2 seems to be an attractive target for the reactivation of p53 and attenuation of oncogenic activity in neuroblastoma.

Methods: In this study, we evaluated the anticancer activities and underlying mechanisms of action of SP141, a first-in-class MDM2 inhibitor, in neuroblastoma cell lines with different p53 backgrounds. The findings were confirmed in mouse xenograft models of neuroblastoma.

Results: We demonstrate that SP141 reduces neuroblastoma cell viability, induces apoptosis, arrests cells at the G2/M phase, and prevents cell migration, independent of p53. In addition, in neuroblastoma xenograft models, SP141 inhibited MDM2 expression and suppressed tumor growth without any host toxicity at the effective dose.

Conclusions: MDM2 inhibition by SP141 results in the inhibition of neuroblastoma growth and metastasis, regardless of the p53 status of the cells and tumors. These findings provide proof-of-concept that SP141 represents a novel treatment option for both p53 wild-type and p53 null neuroblastoma.
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http://dx.doi.org/10.3390/cancers12123651DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7762001PMC
December 2020

Knockout of dihydrofolate reductase in mice induces hypertension and abdominal aortic aneurysm via mitochondrial dysfunction.

Redox Biol 2019 06 29;24:101185. Epub 2019 Mar 29.

Division of Molecular Medicine, Department of Anesthesiology, Division of Cardiology, Department of Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles, 650 Charles E. Young Drive, Los Angeles, CA, 90095, USA. Electronic address:

Hypertension and abdominal aortic aneurysm (AAA) are severe cardiovascular diseases with incompletely defined molecular mechanisms. In the current study we generated dihydrofolate reductase (DHFR) knockout mice for the first time to examine its potential contribution to the development of hypertension and AAA, as well as the underlying molecular mechanisms. Whereas the homozygote knockout mice were embryonically lethal, the heterozygote knockout mice had global reduction in DHFR protein expression and activity. Angiotensin II infusion into these animals resulted in substantially exaggerated elevation in blood pressure and development of AAA, which was accompanied by excessive eNOS uncoupling activity (featured by significantly impaired tetrahydrobiopterin and nitric oxide bioavailability), vascular remodeling (MMP2 activation, medial elastin breakdown and adventitial fibrosis) and inflammation (macrophage infiltration). Importantly, scavenging of mitochondrial reactive oxygen species with Mito-Tempo in vivo completely abrogated development of hypertension and AAA in DHFR knockout mice, indicating a novel role of mitochondria in mediating hypertension and AAA downstream of DHFR deficiency-dependent eNOS uncoupling. These data for the first time demonstrate that targeting DHFR-deficiency driven mitochondrial dysfunction may represent an innovative therapeutic option for the treatment of AAA and hypertension.
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http://dx.doi.org/10.1016/j.redox.2019.101185DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6451172PMC
June 2019

Novel Treatment of Hypertension by Specifically Targeting E2F for Restoration of Endothelial Dihydrofolate Reductase and eNOS Function Under Oxidative Stress.

Hypertension 2019 01;73(1):179-189

From the Division of Molecular Medicine, Department of Anesthesiology, Cardiovascular Research Laboratories (H.L., Q.L., Y.Z., B.G., T.N., K.L.S., J.Y.Y., H.C.), David Geffen School of Medicine, University of California, Los Angeles.

We have shown that hydrogen peroxide (HO) downregulates tetrahydrobiopterin salvage enzyme DHFR (dihydrofolate reductase) to result in eNOS (endothelial NO synthase) uncoupling and elevated blood pressure. Here, we aimed to delineate molecular mechanisms underlying HO downregulation of endothelial DHFR by examining transcriptional pathways hypothesized to modulate DHFR expression and effects on blood pressure regulation of targeting these novel mechanisms. HO dose and time dependently attenuated DHFR mRNA and protein expression and enzymatic activity in endothelial cells. Deletion of E2F-binding sites, but not those of Sp1 (specificity protein 1), abolished HO attenuation of DHFR promoter activity. Overexpression of E2F1/2/3a activated DHFR promoter at baseline and alleviated the inhibitory effect of HO on DHFR promoter activity. HO treatment diminished mRNA and protein expression of E2F1/2/3a, whereas overexpression of E2F isoforms increased DHFR protein levels. Chromatin immunoprecipitation assay indicated direct binding of E2F1/2/3a to the DHFR promoter, which was weakened by HO. E2F1 RNA interference attenuated DHFR protein levels, whereas its overexpression elevated tetrahydrobiopterin levels and tetrahydrobiopterin/dihydrobiopterin ratios in vitro and in vivo. In Ang II (angiotensin II)-infused mice, adenovirus-mediated overexpression of E2F1 markedly abrogated blood pressure to control levels, by restoring endothelial DHFR function to improve NO bioavailability and vasorelaxation. Bioinformatic analyses confirmed a positive correlation between E2F1 and DHFR in human endothelial cells and arteries, and downregulation of both by oxidized phospholipids. In summary, endothelial DHFR is downregulated by HO transcriptionally via an E2F-dependent mechanism, and that specifically targeting E2F1/2/3a to restore DHFR and eNOS function may serve as a novel therapeutic option for the treatment of hypertension.
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http://dx.doi.org/10.1161/HYPERTENSIONAHA.118.11643DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6310047PMC
January 2019

KDM4B protects against obesity and metabolic dysfunction.

Proc Natl Acad Sci U S A 2018 06 29;115(24):E5566-E5575. Epub 2018 May 29.

Laboratory of Molecular Signaling, Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, CA 90095;

Although significant progress has been made in understanding epigenetic regulation of in vitro adipogenesis, the physiological functions of epigenetic regulators in metabolism and their roles in obesity remain largely elusive. Here, we report that KDM4B (lysine demethylase 4B) in adipose tissues plays a critical role in energy balance, oxidation, lipolysis, and thermogenesis. Loss of KDM4B in mice resulted in obesity associated with reduced energy expenditure and impaired adaptive thermogenesis. Obesity in KDM4B-deficient mice was accompanied by hyperlipidemia, insulin resistance, and pathological changes in the liver and pancreas. Adipocyte-specific deletion of revealed that the adipose tissues were the main sites for KDM4B antiobesity effects. KDM4B directly controlled the expression of multiple metabolic genes, including and Collectively, our studies identify KDM4B as an essential epigenetic factor for the regulation of metabolic health and maintaining normal body weight in mice. KDM4B may provide a therapeutic target for treatment of obesity.
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http://dx.doi.org/10.1073/pnas.1721814115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6004484PMC
June 2018

Endothelial cell calpain as a critical modulator of angiogenesis.

Biochim Biophys Acta Mol Basis Dis 2017 06 30;1863(6):1326-1335. Epub 2017 Mar 30.

Division of Molecular Medicine, Department of Anesthesiology, David Geffen School of Medicine at University of California Los Angeles (UCLA), CA 90095, USA; Division of Cardiology, Department Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles (UCLA), CA 90095, USA. Electronic address:

Calpains are a family of calcium-dependent non-lysosomal cysteine proteases. In particular, calpains residing in the endothelial cells play important roles in angiogenesis. It has been shown that calpain activity can be increased in endothelial cells by growth factors, primarily vascular endothelial growth factor (VEGF). VEGF/VEGFR2 induces calpain 2 dependent activation of PI3K/AMPK/Akt/eNOS pathway, and consequent nitric oxide production and physiological angiogenesis. Under pathological conditions such as tumor angiogenesis, endothelial calpains can be activated by hypoxia. This review focuses on the molecular regulatory mechanisms of calpain activation, and the newly identified mechanistic roles and downstream signaling events of calpains in physiological angiogenesis, and in the conditions of pathological tumor angiogenesis and diabetic wound healing, as well as retinopathy and atherosclerosis that are also associated with an increase in calpain activity. Further discussed include the differential strategies of modulating angiogenesis through manipulating calpain expression/activity in different pathological settings. Targeted limitation of angiogenesis in cancer and targeted promotion of angiogenesis in diabetic wound healing via modulations of calpains and calpain-dependent signaling mechanisms are of significant translational potential. Emerging strategies of tissue-specific targeting, environment-dependent targeting, and genome-targeted editing may turn out to be effective regimens for targeted manipulation of angiogenesis through calpain pathways, for differential treatments including both attenuation of tumor angiogenesis and potentiation of diabetic angiogenesis.
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http://dx.doi.org/10.1016/j.bbadis.2017.03.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511073PMC
June 2017

Attenuation of neointimal formation with netrin-1 and netrin-1 preconditioned endothelial progenitor cells.

J Mol Med (Berl) 2017 03 21;95(3):335-348. Epub 2016 Dec 21.

Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles, 650 Charles E. Young Drive, Los Angeles, CA, 90095, USA.

Restenosis after angioplasty is a serious clinical problem that can result in re-occlusion of the coronary artery. Although current drug-eluting stents have proved to be more effective in reducing restenosis, they have drawbacks of inhibiting reendothelialization to promote thrombosis. New treatment options are in urgent need. We have shown that netrin-1, an axon-guiding protein, promotes angiogenesis and cardioprotection via production of nitric oxide (NO). The present study examined whether and how netrin-1 attenuates neointimal formation in a femoral wire injury model. Infusion of netrin-1 into C57BL/6 mice markedly attenuated neointimal formation following wire injury of femoral arteries, measured by intimal to media ratio (from 1.94 ± 0.55 to 0.45 ± 0.86 at 4 weeks). Proliferation of VSMC in situ was largely reduced. This protective effect was absent in DCC animals. NO production was increased by netrin-1 in both intact and injured femoral arteries, indicating netrin-1 stimulation of endogenous NO production from intact endothelium and remaining endothelial cells post-injury. VSMC migration was abrogated by netrin-1 via a NO/cGMP/p38 MAPK pathway, while timely EPC homing was induced. Injection of netrin-1 preconditioned wild-type EPCs, but not EPCs of DCC animals, substantially attenuated neointimal formation. EPC proliferation, NO production, and resistance to oxidative stress induced apoptosis were augmented by netrin-1 treatment. In conclusion, our data for the first time demonstrate that netrin-1 is highly effective in reducing neointimal formation following vascular endothelial injury, which is dependent on DCC, and attributed to inhibition of VSMC proliferation and migration, as well as improved EPC function. These data may support usage of netrin-1 and netrin-1 preconditioned EPCs as novel therapies for post angioplasty restenosis.

Key Message: Netrin-1 attenuates neointimal formation following post endothelial injury via DCC and NO. Netrin-1 inhibits VSMC proliferation in situ following endothelial injury. Netrin-1 inhibits VSMC migration via a NO/cGMP/p38 MAPK pathway. Netrin-1 augments proliferation of endothelial progenitor cells (EPCs) and EPC eNOS/NO activation. Netrin-1 enhances resistance of EPCs to oxidative stress, improving re-endothelialization following injury.
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http://dx.doi.org/10.1007/s00109-016-1490-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5976243PMC
March 2017

NOX isoforms in the development of abdominal aortic aneurysm.

Redox Biol 2017 04 19;11:118-125. Epub 2016 Nov 19.

Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles, 650 Charles E. Young Drive, Los Angeles, CA 90095, USA. Electronic address:

Oxidative stress plays an important role in the formation of abdominal aortic aneurysm (AAA), and we have recently established a causal role of uncoupled eNOS in this severe human disease. We have also shown that activation of NADPH oxidase (NOX) lies upstream of uncoupled eNOS. Therefore, identification of the specific NOX isoforms that are required for eNOS uncoupling and AAA formation would ultimately lead to novel therapies for AAA. In the present study, we used the Ang II infused hph-1 mice to examine the roles of NOX isoforms in the development of AAA. We generated double mutants of hph-1-NOX1, hph-1-NOX2, hph-1-p47phox, and hph-1-NOX4. After two weeks of Ang II infusion, the incidence rate of AAA substantially dropped from 76.5% in Ang II infused hph-1 mice (n=34) to 11.1%, 15.0%, 9.5% and 0% in hph-1-NOX1 (n=27), hph-1-NOX2 (n=40), hph-1-p47phox (n=21), and hph-1-NOX4 (n=33) double mutant mice, respectively. The size of abdominal aortas of the four double mutant mice, determined by ultrasound analyses, was significantly smaller than the hph-1 mice. Aortic nitric oxide and HB bioavailabilities were markedly improved in the double mutants, while superoxide production and eNOS uncoupling activity were substantially diminished. These effects seemed attributed to an endothelial specific restoration of dihydrofolate reductase expression and activity, deficiency of which has been shown to induce eNOS uncoupling and AAA formation in both Ang II-infused hph-1 and apoE null animals. In addition, over-expression of human NOX4 N129S or T555S mutant newly identified in aneurysm patients increased hydrogen peroxide production, further implicating a relationship between NOX and human aneurysm. Taken together, these data indicate that NOX isoforms 1, 2 or 4 lies upstream of dihydrofolate reductase deficiency and eNOS uncoupling to induce AAA formation. These findings may promote development of novel therapeutics for the treatment of the disease by inhibiting NOX signaling.
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http://dx.doi.org/10.1016/j.redox.2016.11.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5133668PMC
April 2017

Protein Phosphotyrosine Phosphatase 1B (PTP1B) in Calpain-dependent Feedback Regulation of Vascular Endothelial Growth Factor Receptor (VEGFR2) in Endothelial Cells: IMPLICATIONS IN VEGF-DEPENDENT ANGIOGENESIS AND DIABETIC WOUND HEALING.

J Biol Chem 2017 Jan 21;292(2):407-416. Epub 2016 Nov 21.

From the Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles (UCLA), California 90095

The VEGF/VEGFR2/Akt/eNOS/NO pathway is essential to VEGF-induced angiogenesis. We have previously discovered a novel role of calpain in mediating VEGF-induced PI3K/AMPK/Akt/eNOS activation through Ezrin. Here, we sought to identify possible feedback regulation of VEGFR2 by calpain via its substrate protein phosphotyrosine phosphatase 1B (PTP1B), and the relevance of this pathway to VEGF-induced angiogenesis, especially in diabetic wound healing. Overexpression of PTP1B inhibited VEGF-induced VEGFR2 and Akt phosphorylation in bovine aortic endothelial cells, while PTP1B siRNA increased both, implicating negative regulation of VEGFR2 by PTP1B. Calpain inhibitor ALLN induced VEGFR2 activation, which can be completely blocked by PTP1B overexpression. Calpain activation induced by overexpression or Ca/A23187 resulted in PTP1B cleavage, which can be blocked by ALLN. Moreover, calpain activation inhibited VEGF-induced VEGFR2 phosphorylation, which can be restored by PTP1B siRNA. These data implicate calpain/PTP1B negative feedback regulation of VEGFR2, in addition to the primary signaling pathway of VEGF/VEGFR2/calpain/PI3K/AMPK/Akt/eNOS. We next examined a potential role of PTP1B in VEGF-induced angiogenesis. Endothelial cells transfected with PTP1B siRNA showed faster wound closure in response to VEGF. Aortic discs isolated from PTP1B siRNA-transfected mice also had augmented endothelial outgrowth. Importantly, PTP1B inhibition and/or calpain overexpression significantly accelerated wound healing in STZ-induced diabetic mice. In conclusion, our data for the first time demonstrate a calpain/PTP1B/VEGFR2 negative feedback loop in the regulation of VEGF-induced angiogenesis. Modulation of local PTP1B and/or calpain activities may prove beneficial in the treatment of impaired wound healing in diabetes.
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http://dx.doi.org/10.1074/jbc.M116.766832DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5241720PMC
January 2017

Catabolic Defect of Branched-Chain Amino Acids Promotes Heart Failure.

Circulation 2016 May 8;133(21):2038-49. Epub 2016 Apr 8.

From Key Laboratory of Cell Differentiation and Apoptosis of Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (H.S., M.Z., Y.L., Y.W.); Division of Molecular Medicine, Departments of Anesthesiology, Medicine, and Physiology, Molecular Biology Institute, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California, Los Angeles (H.S., C.G., Z.W., J.-Y.Y., S.R., C.D.R., H.C., X.X., Y.W.); Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA (K.C.O., C.L.); Case Cardiovascular Research Institute, Harrington Heart and Vascular Institute, Department of Medicine, Case Western Reserve University, Cleveland, OH (D.A.P., D.J., M.K.J.); Division of Cardiology, Department of Medicine (S.S.) and Sarah W. Stedman Nutrition and Metabolism Center, Departments of Medicine and Pharmacology and Cancer Biology (O.I., C.B.N.), and Duke University School of Medicine, Durham, NC; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas (W.-J.G., N.S.W., R.M.W., D.T.C.); and Division of Cardiology, Department of Medicine, Columbia University Medical Center, New York, NY (P.C.S.). Dr Schulze is now at the Department of Internal Medicine, Division of Cardiology, Angiology, Pneumology and Intensive Medical Care, Friedrich-Schiller-University, Jena, Germany.

Background: Although metabolic reprogramming is critical in the pathogenesis of heart failure, studies to date have focused principally on fatty acid and glucose metabolism. Contribution of amino acid metabolic regulation in the disease remains understudied.

Methods And Results: Transcriptomic and metabolomic analyses were performed in mouse failing heart induced by pressure overload. Suppression of branched-chain amino acid (BCAA) catabolic gene expression along with concomitant tissue accumulation of branched-chain α-keto acids was identified as a significant signature of metabolic reprogramming in mouse failing hearts and validated to be shared in human cardiomyopathy hearts. Molecular and genetic evidence identified the transcription factor Krüppel-like factor 15 as a key upstream regulator of the BCAA catabolic regulation in the heart. Studies using a genetic mouse model revealed that BCAA catabolic defect promoted heart failure associated with induced oxidative stress and metabolic disturbance in response to mechanical overload. Mechanistically, elevated branched-chain α-keto acids directly suppressed respiration and induced superoxide production in isolated mitochondria. Finally, pharmacological enhancement of branched-chain α-keto acid dehydrogenase activity significantly blunted cardiac dysfunction after pressure overload.

Conclusions: BCAA catabolic defect is a metabolic hallmark of failing heart resulting from Krüppel-like factor 15-mediated transcriptional reprogramming. BCAA catabolic defect imposes a previously unappreciated significant contribution to heart failure.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.115.020226DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4879058PMC
May 2016

Reply: To PMID 25882860.

J Hypertens 2015 Nov;33(11):2368-70

Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA.

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http://dx.doi.org/10.1097/HJH.0000000000000724DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4819245PMC
November 2015

Bone Morphogenic Protein 4 Mediates NOX1-Dependent eNOS Uncoupling, Endothelial Dysfunction, and COX2 Induction in Type 2 Diabetes Mellitus.

Mol Endocrinol 2015 Aug 29;29(8):1123-33. Epub 2015 Jun 29.

Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardivascular Research Laboratories, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095.

We have recently shown that angiotensin II-mediated uncoupling of endothelial nitric oxide synthase (eNOS) contributes to endothelial dysfunction in streptozotocin-induced type 1 diabetes mellitus. However, it has remained unclear whether and how eNOS uncoupling occurs in type 2 diabetes mellitus (T2DM) and the consequences of such in regulating vascular function. Here we investigated a role of bone morphogenic protein (BMP)-4 in mediating eNOS uncoupling, endothelial dysfunction, and inflammation in db/db mice. Circulating levels of BMP4 were markedly elevated in db/db mice but not in mice with type 1 diabetes mellitus, in which angiotensin II levels were significantly increased. Infusion of BMP4 antagonist noggin into db/db mice (15 μg/kg/day, 4 weeks) abolished eNOS uncoupling activity while restoring tetrahydrobiopterin (H(4)B) bioavailability. The impaired endothelium-dependent vasorelaxation in db/db aortas was significantly improved by noggin infusion. Exposure of aortic endothelial cells to BMP4 (50 ng/mL, 24 hours) resulted in eNOS uncoupling, which was attenuated by H(4)B precursor sepiapterin or small interfering RNA silencing nicotinamide adenine dinucleotide phosphate oxidase isoform 1 (NOX1). Interestingly, BMP4-dependent NOX1 up-regulation was abrogated by sepiapterin, implicating a NOX1-uncoupled eNOS-NOX1 feed-forward loop. BMP4 induction of cyclooxygenase 2 (COX2) expression and vascular cell adhesion protein 1 was found in db/db mice. Consistently, COX2 was up-regulated by BMP4 in endothelial cells, which was attenuated by sepiapterin, implicating an upstream role of eNOS uncoupling in COX2-mediated inflammatory activation. Taken together, our data for the first time reveal a novel role of BMP4 in inducing NOX1-dependent eNOS uncoupling in T2DM, which may promote development of novel therapeutics restoring endothelial function in T2DM.
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http://dx.doi.org/10.1210/ME.2014-1313DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4518001PMC
August 2015

Etch characteristics of magnetic tunnel junction materials using bias pulsing in the CH4/N2O inductively coupled plasma.

J Nanosci Nanotechnol 2014 Dec;14(12):9541-7

The etch characteristics of magnetic tunneling junction (MTJ) related materials such as CoFeB, MgO, FePt, Ru, and W as hard mask have been investigated as functions of rf pulse biasing, substrate heating, and CH4/N2O gas combination in an inductively coupled plasma system. When CH4/N2O gas ratio was varied, at CH4/N2O gas ratio of 2:1, not only the highest etch rates but also the highest etch selectivity over W could be obtained. By increasing the substrate temperature, the linear increase of both the etch rates of MTJ materials and the etch selectivity over W could be obtained. The use of the rf pulse biasing improved the etch selectivity of the MTJ materials over hard mask such as W further. The surface roughness and residual thickness remaining on the etched surface of the CoFeB were also decreased by using rf pulse biasing and with the decrease of rf duty percentage. The improvement of etch characteristics by substrate heating and rf pulse biasing was possibly related to the formation of more stable and volatile etch compounds and the removal of chemically reacted compounds more easily on the etched CoFeB surface. Highly selective etching of MTJ materials over the hard mask could be obtained by using the rf pulse biasing of 30% of duty ratio and by increasing the substrate temperature to 200 degrees C in the CH4/N2O (2:1) plasmas.
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http://dx.doi.org/10.1166/jnn.2014.10190DOI Listing
December 2014

Mechanisms and consequences of endothelial nitric oxide synthase dysfunction in hypertension.

J Hypertens 2015 Jun;33(6):1128-36

Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA.

Reduced nitric oxide bioavailability contributes to endothelial dysfunction and hypertension. The endothelial isoform of nitric oxide synthase (eNOS) is responsible for the production of nitric oxide within the endothelium. Loss of eNOS cofactor tetrahydrobiopterin to initial increase in oxidative stress leads to uncoupling of eNOS, in which the enzyme produces superoxide anion rather than nitric oxide, further substantiating oxidative stress to induce vascular pathogenesis. The current review focuses on recent advances on the molecular mechanisms and consequences of eNOS dysfunction in hypertension, and potential novel therapeutic strategies restoring eNOS function to treat hypertension.
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http://dx.doi.org/10.1097/HJH.0000000000000587DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4816601PMC
June 2015

Fueling up skeletal muscle to reduce obesity: A TrkB story.

Chem Biol 2015 Mar;22(3):311-2

Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA. Electronic address:

Targeting TrkB signaling could represent a good therapeutic strategy to prevent obesity. In this issue of Chemistry & Biology, Chan et al. report the efficacy of 7,8-DHT, a TrkB agonist, in preventing obesity in female mice. The underlying molecular mechanisms behind this activity seem to involve increased energy expenditure in skeletal muscle.
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http://dx.doi.org/10.1016/j.chembiol.2015.03.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4817994PMC
March 2015

Netrin-1 improves post-injury cardiac function in vivo via DCC/NO-dependent preservation of mitochondrial integrity, while attenuating autophagy.

Biochim Biophys Acta 2015 Feb 10;1852(2):277-89. Epub 2014 Jun 10.

Divisions of Molecular Medicine and Cardiology, Departments of Anesthesiology and Medicine, Cardiovascular Research Laboratories, David Geffen School of Medicine at University of California Los Angeles, 650 Charles E. Young Drive, Los Angeles, CA 90095, USA. Electronic address:

Reperfusion injury of the heart is a severe complication of angioplasty treatment of acute myocardial ischemia, for which no therapeutics are currently available. The present study aimed to identify whether and how a novel protein, netrin-1, induces cardioprotection in vivo during ischemia/reperfusion (I/R) injury. Wild type (WT) C57BL6/J mice were subjected to a 30 min coronary occlusion followed by a 24h reperfusion with vehicle (normal saline), netrin-1, UO126 (MEK1/2 inhibitor), PTIO (nitric oxide/NO scavenger), netrin-1/UO126 or netrin-1/PTIO intraventricularly. Some were injected of netrin-1 via tail vein. Netrin-1 at 5μg/kg induced a substantial reduction in infarct size (19.7 ± 5.0% from 41.3 ± 1.8% in the controls), and markedly improved cardiac function as measured by ejection fraction and fractional shortening from echocardiography. Experiments with mice deficient in netrin-1 receptor DCC (deleted in colorectal cancer, DCC+/-), or reperfusion with netrin-1/UO126 or netrin-1/PTIO, attenuated the protective effects of netrin-1, implicating intermediate roles of DCC, ERK1/2 and NO. Netrin-1 induced phosphorylation of ERK1/2 and eNOS was abolished in DCC+/-mice. Electron spin resonance (ESR) determination of NO production from isolated left ventricles demonstrated that netrin-1 improves NO bioavailability, which was attenuated by UO126 or in DCC+/-mice, suggesting upstream roles of DCC and ERK1/2 in NO production. Netrin-1 further reduced mitochondrial swelling and mitochondrial superoxide production, which was absent when co-treated with PTIO or UO126, or in DCC+/-mice, indicating critical roles of DCC, ERK1/2 and NO in preserving mitochondrial integrity. In a permanent coronary ligation model of myocardial infarction (MI) to assess post-MI remodeling, netrin-1 abolished the marked increase in autophagy. In summary, our data demonstrate robust cardioprotective effect of netrin-1 in vivo, as shown by reduced infarct size and improved cardiac function. Mechanistically, this protection is mediated by netrin-1 receptor DCC, and NO dependent preservation of mitochondria. This work clearly establishes a therapeutic potential of netrin-1 for acute treatment of MI, perhaps also for chronic post-MI remodeling. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.
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http://dx.doi.org/10.1016/j.bbadis.2014.06.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4262720PMC
February 2015

Role of vascular oxidative stress in obesity and metabolic syndrome.

Diabetes 2014 Jul 18;63(7):2344-55. Epub 2014 Feb 18.

Division of Molecular Medicine and Cardiology, Cardiovascular Research Laboratories, Departments of Anesthesiology and Medicine, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA

Obesity is associated with vascular diseases that are often attributed to vascular oxidative stress. We tested the hypothesis that vascular oxidative stress could induce obesity. We previously developed mice that overexpress p22phox in vascular smooth muscle, tg(sm/p22phox), which have increased vascular ROS production. At baseline, tg(sm/p22phox) mice have a modest increase in body weight. With high-fat feeding, tg(sm/p22phox) mice developed exaggerated obesity and increased fat mass. Body weight increased from 32.16 ± 2.34 g to 43.03 ± 1.44 g in tg(sm/p22phox) mice (vs. 30.81 ± 0.71 g to 37.89 ± 1.16 g in the WT mice). This was associated with development of glucose intolerance, reduced HDL cholesterol, and increased levels of leptin and MCP-1. Tg(sm/p22phox) mice displayed impaired spontaneous activity and increased mitochondrial ROS production and mitochondrial dysfunction in skeletal muscle. In mice with vascular smooth muscle-targeted deletion of p22phox (p22phox(loxp/loxp)/tg(smmhc/cre) mice), high-fat feeding did not induce weight gain or leptin resistance. These mice also had reduced T-cell infiltration of perivascular fat. In conclusion, these data indicate that vascular oxidative stress induces obesity and metabolic syndrome, accompanied by and likely due to exercise intolerance, vascular inflammation, and augmented adipogenesis. These data indicate that vascular ROS may play a causal role in the development of obesity and metabolic syndrome.
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http://dx.doi.org/10.2337/db13-0719DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4066332PMC
July 2014

Oxidative stress in atrial fibrillation: an emerging role of NADPH oxidase.

J Mol Cell Cardiol 2013 Sep 2;62:72-9. Epub 2013 May 2.

Divisions of Molecular Medicine and Cardiology, Department of Anesthesiology, Cardiovascular Research Laboratory (CVRL), David Geffen School of Medicine at University of California Los Angeles (UCLA), Los Angeles, CA, USA.

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Patients with AF have up to seven-fold higher risk of suffering from ischemic stroke. Better understanding of etiologies of AF and its thromboembolic complications are required for improved patient care, as current anti-arrhythmic therapies have limited efficacy and off target effects. Accumulating evidence has implicated a potential role of oxidative stress in the pathogenesis of AF. Excessive production of reactive oxygen species (ROS) is likely involved in the structural and electrical remodeling of the heart, contributing to fibrosis and thrombosis. In particular, NADPH oxidase (NOX) has emerged as a potential enzymatic source for ROS production in AF based on growing evidence from clinical and animal studies. Indeed, NOX can be activated by known upstream triggers of AF such as angiotensin II and atrial stretch. In addition, treatments such as statins, antioxidants, ACEI or AT1RB have been shown to prevent post-operative AF; among which ACEI/AT1RB and statins can attenuate NOX activity. On the other hand, detailed molecular mechanisms by which specific NOX isoform(s) are involved in the pathogenesis of AF and the extent to which activation of NOX plays a causal role in AF development remains to be determined. The current review discusses causes and consequences of oxidative stress in AF with a special focus on the emerging role of NOX pathways.
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http://dx.doi.org/10.1016/j.yjmcc.2013.04.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3735724PMC
September 2013

Intralipid, a clinically safe compound, protects the heart against ischemia-reperfusion injury more efficiently than cyclosporine-A.

Anesthesiology 2012 Oct;117(4):836-46

Department of Anesthesiology, Division of Molecular Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California 90095-7115, USA.

Background: We have recently shown that postischemic administration of intralipid protects the heart against ischemia-reperfusion injury. Here we compared the cardioprotective effects of intralipid with cyclosporine-A, a potent inhibitor of the mitochondrial permeability transition pore opening.

Methods: In vivo rat hearts or isolated Langendorff-perfused mouse hearts were subjected to ischemia followed by reperfusion with intralipid (0.5%, 1% and 2% ex-vivo, and 20% in vivo), cyclosporine-A (0.2 μM, 0.8 μM, and 1.5 μM ex- vivo and 10 mg/kg in vivo), or vehicle. The hemodynamic function, infarct size, calcium retention capacity, mitochondrial superoxide production, and phosphorylation levels of protein kinase B (Akt)/glycogen synthase kinase-3β (GSK-3β) were measured. The values are mean ± SEM.

Results: Administration of intralipid at reperfusion significantly reduced myocardial infarct size compared with cyclosporine-A in vivo (infarct size/area at risk)%: 22.9 ± 2.5% vs. 35.2 ± 3.5%; P = 0.030, n = 7/group). Postischemic administration of intralipid at its optimal dose (1%) was more effective than cyclosporine-A (0.8 μM) in protecting the ex vivo heart against ischemia-reperfusion injury, as the rate pressure product at the end of reperfusion was significantly higher (mmHg · beats/min: 12,740 ± 675 [n = 7] vs. 9,203 ± 10,781 [n = 5], P = 0.024), and the infarct size was markedly smaller (17.3 ± 2.9 [n = 7] vs. 29.2 ± 2.7 [n = 5], P = 0.014). Intralipid was as efficient as cyclosporine-A in inhibiting the mitochondrial permeability transition pore opening (calcium retention capacity = 280 ± 8.2 vs. 260.3 ± 2.9 nmol/mg mitochondria protein in cyclosporine-A, P = 0.454, n = 6) and in reducing cardiac mitochondrial superoxide production. Unlike intralipid, which increased phosphorylation of Akt (6-fold) and GSK-3β (5-fold), cyclosporine-A had no effect on the activation of these prosurvival kinases.

Conclusions: Although intralipid inhibits the opening of the mitochondrial permeability transition pore as efficiently as cyclosporine-A, intralipid is more effective in reducing the infarct size and improving the cardiac functional recovery.
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http://dx.doi.org/10.1097/ALN.0b013e3182655e73DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3769111PMC
October 2012

NOX4-Dependent Hydrogen Peroxide Overproduction in Human Atrial Fibrillation and HL-1 Atrial Cells: Relationship to Hypertension.

Front Physiol 2012 5;3:140. Epub 2012 Jun 5.

Division of Molecular Medicine, Cardiovascular Research Laboratories, Department of Anesthesiology, David Geffen School of Medicine at University of California Los Angeles Los Angeles, CA, USA.

Background/objectives: Atrial fibrillation (AF) is the most common type of cardiac arrhythmia with patients dying frequently of stroke. In view of the unclear etiologies of AF and a potential role of oxidative stress, the present study examined cardiac reactive oxygen species production and NADPH oxidase (NOX) expression in AF patients.

Methods And Results: Patients with AF were older than those without (58.8 ± 11.7 vs. 47.8 ± 19.2, p = 0.047). Whereas total [Formula: see text] production (determined by electron spin resonance) was similar in patients with and without AF, H(2)O(2) production was more than doubled in AF patients (149.8 ± 26.28 vs. 66.9 ± 7.14 pmol/mg/min, p = 0.0055), which correlated well with a doubling in NOX isoform 4 (NOX4) expression. AF patients with co-existing hypertension had three-fold higher H(2)O(2) production compared to those without (239.0 ± 125.1 vs. 83.6 ± 51.3 pmol/mg/min, p = 0.003). Treatment of HL-1 atrial cells with angiotensin II, a known modulator of atrial structural remodeling, resulted in upregulation of NOX4 and H(2)O(2) production, further implicating a potential role of NOX4 in atrial remodeling.

Conclusion: Our data represent the first implication that NOX4-derived H(2)O(2) may play an important role in the etiologies of AF.
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http://dx.doi.org/10.3389/fphys.2012.00140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367314PMC
October 2012

Cardiac vulnerability to ischemia/reperfusion injury drastically increases in late pregnancy.

Basic Res Cardiol 2012 Jul 31;107(4):271. Epub 2012 May 31.

Department of Anesthesiology, Division of Molecular Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-7115, USA.

Although the murine late pregnant (LP) heart is speculated to be a better functioning heart during physiological conditions, the susceptibility of LP hearts to I/R injury is still unknown. The aims of this study were to investigate the cardiac vulnerability of LP rodents to ischemia/reperfusion (I/R) injury and to explore its underlying mechanisms. In vivo female rat hearts [non-pregnant (NP) or LP] or ex vivo Langendorff-perfused mouse hearts were subjected to I/R. The infarct size was approximately fourfold larger in LP animals compared with NP both in vivo and ex vivo. The heart functional recovery was extremely poor in LP mice compared with NP (~10% recovery in LP vs. 80% recovery in NP at the end of reperfusion, P < 0.01). Interestingly, the poor functional recovery and the larger infarct size in LP were partially restored one day post-partum and almost fully restored 1 week post-partum to their corresponding NP levels. Mitochondrial respiratory function and the threshold for opening of the mitochondrial permeability transition pore were significantly lower in LP compared with NP when they both were subjected to myocardial I/R injury [Respiratory control ratio = 1.9 ± 0.1 vs. 4.0 ± 0.5 in NP, P < 0.05; calcium retention capacity (CRC) = 167 ± 10 vs. 233 ± 18 nmol/mg protein in NP, P < 0.01]. Cardiac reactive oxygen species (ROS) generation, as well mitochondrial superoxide production, was approximately twofold higher in LP compared with NP following I/R. The phosphorylation levels of Akt, ERK1/2, and STAT3, but not GSK3β, were significantly reduced in the hearts from LP subjected to I/R. In conclusion, increased mitochondrial ROS generation, decreased CRC as well as impaired activation of Akt/ERK/STAT3 at reperfusion are the possible underlying mechanisms for higher vulnerability of LP hearts to I/R.
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http://dx.doi.org/10.1007/s00395-012-0271-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3769136PMC
July 2012

Inhibition of XO or NOX attenuates diethylstilbestrol-induced endothelial nitric oxide deficiency without affecting its effects on LNCaP cell invasion and apoptosis.

Clin Sci (Lond) 2012 Oct;123(8):509-18

Division of Molecular Medicine, Cardiovascular Research Laboratories, Departments of Anesthesiology and Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095, U.S.A.

Oestrogen protects cardiovascular health partially via an up-regulation of NO• (NO radical) production. Its synthetic analogue DES (diethylstilbestrol), used as a potent androgen deprivation therapy for patients with prostate cancer, is however associated with high incidence of thromboembolic events. Exposure of BAECs (bovine aortic endothelial cells) to pharmacologically relevant dosage (12.5 μmol/l, 24 h) of DES resulted in a marked reduction in endothelial NO• bioavailability determined by ESR (electron spin resonance), while 17β-oestradiol instead increased NO• production as expected. Intriguingly, endothelial O(2)•- (superoxide anion) production was up-regulated by DES in vitro and in vivo, which was, however, attenuated by the ER (oestrogen receptor) antagonist ICI 182780, the XO (xanthine oxidase) inhibitor oxypurinol or the NOX (NADPH oxidase) inhibitor NSC23766. These agents also restored NO• production. DES alone in a cell-free system did not produce any ESR-sound O(2)•- signal. Of note, eNOS (endothelial NO synthase) mRNA and protein remained unchanged in response to DES. These results suggest that receptor-dependent activation of XO or NOX, and subsequent production of O(2)•-, mediate DES-induced NO• deficiency. This could represent a previously unrecognized mechanism that is responsible for cardiovascular complications of DES administration. Importantly, DES-induced suppression of LNCaP cell invasion and apoptosis were not affected by XO or NOX inhibitor. Therefore combinatorial therapy of DES and XO/NOX inhibitor may prove to be an innovative and useful therapeutic option in eliminating cardiovascular complications of DES, while preserving its anti-cancer effects, benefiting patients with advanced cancer who do not respond well to any other treatments but DES.
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http://dx.doi.org/10.1042/CS20110407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3675905PMC
October 2012

Endothelium-specific sepiapterin reductase deficiency in DOCA-salt hypertension.

Am J Physiol Heart Circ Physiol 2012 Jun 30;302(11):H2243-9. Epub 2012 Mar 30.

Division of Molecular Medicine, Cardiovascular Research Laboratories, Department of Anesthesiology, David Geffen School of Medicine at University of California Los Angeles, 90095, USA.

The endothelial nitric oxide synthase (eNOS) requires tetrahydrobiopterin (H(4)B) as a cofactor and, in its absence, produces superoxide (O(2)(·-)) rather than nitric oxide (NO(·)), a condition referred to as eNOS uncoupling. DOCA-salt-induced hypertension is associated with H(4)B oxidation and uncoupling of eNOS. The present study investigated whether administration of sepiapterin or H(4)B recouples eNOS in DOCA-salt hypertension. Bioavailable NO(·) detected by electron spin resonance was markedly reduced in aortas of DOCA-salt hypertensive mice. Preincubation with sepiapterin (10 μmol/l for 30 min) failed to improve NO(·) bioavailability in hypertensive aortas while it augmented NO(·) production from control vessels, implicating a hypertension-associated deficiency in sepiapterin reductase (SPR), the rate-limiting enzyme for sepiapterin conversion to H(4)B. Indeed, a decreased SPR expression was observed in aortic endothelial cells, but not in endothelium-denuded aortic remains, implicating an endothelium-specific SPR deficiency. Administration of hypertensive aortas with H(4)B (10 μmol/l, 30 min) partially restored vascular NO(·) production. Combined administration of H(4)B and the NADPH oxidase inhibitor apocynin (100 μmol/l, 30 min) fully restored NO(·) bioavailability while reducing O(2)(·-) production. In angiotensin II-induced hypertension, however, aortic endothelial SPR expression was not affected. In summary, administration of sepiapterin is not effective in recoupling eNOS in DOCA-salt hypertension, due to an endothelium-specific loss in SPR, whereas coadministration of H(4)B and apocynin is highly efficient in recoupling eNOS. This is consistent with our previous observations that in angiotensin II hypertension, endothelial deficiency in dihydrofolate reductase is alternatively responsible for uncoupling of eNOS. Taken together, these data indicate that strategies specifically targeting at different H(4)B metabolic enzymes might be necessary in restoring eNOS function in different types of hypertension.
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http://dx.doi.org/10.1152/ajpheart.00835.2011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3378300PMC
June 2012

Aminoguanidine inhibits aortic hydrogen peroxide production, VSMC NOX activity and hypercontractility in diabetic mice.

Cardiovasc Diabetol 2009 Dec 30;8:65. Epub 2009 Dec 30.

Department of Anesthesiology, David Geffen School of Medicine at University of California Los Angeles (UCLA), Los Angeles, CA, USA.

Background: Dysfunctionally uncoupled endothelial nitric oxide synthase (eNOS) is involved in producing reactive oxygen species (ROS) in the diabetic endothelium. The present study investigated whether anti-diabetes drug Aminoguanidine (AG) has any effect on eNOS function and vascular oxidant stress.

Methods And Results: Blood glucose levels were increased to 452.0 +/- 15.1 mg/dl in STZ-treated male C57BL/6J mice (148.4 +/- 3.2 mg/dl in untreated controls). Aortic productions of NO* and O(2)*- were measured specifically and sensitively using electron spin resonance. Diabetic mice had a marked increase in aortic O(2)*- production. Aortic hydrogen peroxide (H(2)O(2)) production was also increased in diabetic aortas and significantly attenuated by AG. AG however had only a marginal effect in reducing aortic O(2)*- production, which corresponded to a minimal effect in improving aortic nitric oxide (NO*) bioavailability. The endothelium-dependent vasodilatation however was modestly but significantly improved by AG, likely consequent to AG-induced reduction in hyper-contractility. NAD(P)H oxidase (NOX)-dependent O(2)*- production was completely attenuated by AG in endothelium-denuded diabetic aortas.

Conclusion: In summary, despite that AG is not an effective eNOS recoupling agent presumably consequent to its ineffectiveness in preventing endothelial NOX activation, it is inhibitory of aortic H(2)O(2) production, VSMC NOX activity, and hypercontractility in diabetes.
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http://dx.doi.org/10.1186/1475-2840-8-65DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2811700PMC
December 2009

Protein phosphatase 2Cm is a critical regulator of branched-chain amino acid catabolism in mice and cultured cells.

J Clin Invest 2009 Jun;119(6):1678-87

Division of Molecular Medicine, Department of Anesthesiology, David Geffen School of Medicine, UCLA, Los Angeles, California 90095, USA.

The branched-chain amino acids (BCAA) are essential amino acids required for protein homeostasis, energy balance, and nutrient signaling. In individuals with deficiencies in BCAA, these amino acids can be preserved through inhibition of the branched-chain-alpha-ketoacid dehydrogenase (BCKD) complex, the rate-limiting step in their metabolism. BCKD is inhibited by phosphorylation of its E1alpha subunit at Ser293, which is catalyzed by BCKD kinase. During BCAA excess, phosphorylated Ser293 (pSer293) becomes dephosphorylated through the concerted inhibition of BCKD kinase and the activity of an unknown intramitochondrial phosphatase. Using unbiased, proteomic approaches, we have found that a mitochondrial-targeted phosphatase, PP2Cm, specifically binds the BCKD complex and induces dephosphorylation of Ser293 in the presence of BCKD substrates. Loss of PP2Cm completely abolished substrate-induced E1alpha dephosphorylation both in vitro and in vivo. PP2Cm-deficient mice exhibited BCAA catabolic defects and a metabolic phenotype similar to the intermittent or intermediate types of human maple syrup urine disease (MSUD), a hereditary disorder caused by defects in BCKD activity. These results indicate that PP2Cm is the endogenous BCKD phosphatase required for nutrient-mediated regulation of BCKD activity and suggest that defects in PP2Cm may be responsible for a subset of human MSUD.
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http://dx.doi.org/10.1172/JCI38151DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2689111PMC
June 2009

An ezrin/calpain/PI3K/AMPK/eNOSs1179 signaling cascade mediating VEGF-dependent endothelial nitric oxide production.

Circ Res 2009 Jan 26;104(1):50-9. Epub 2008 Nov 26.

Division of Molecular Medicine, Cardiovascular Research Laboratories, Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.

Calpain was recently reported to mediate vascular endothelial growth factor (VEGF)-induced angiogenesis. In the present study, we investigated detailed molecular mechanisms. VEGF (100 ng/mL) induced a marked increase in endothelial cell production of NO(*), specifically detected by electron spin resonance. This response was abolished by inhibition of calpain with N-acetyl-leucyl-leucyl-norleucinal (ALLN) or Calpeptin. Both also diminished membrane-specific calpain activation by VEGF, which was intriguingly attenuated by silencing ezrin with RNA interference. A rapid membrane colocalization of calpain and ezrin occurred as short as 10 minutes after VEGF stimulation. AKT, AMP-dependent kinase (AMPK), and endothelial nitric oxide synthase (eNOS)(s1179) phosphorylations in VEGF-stimulated endothelial cells were markedly enhanced, which were however significantly attenuated by either ALLN, Calpeptin, or ezrin small interfering RNA, as well as by Wortmannin or compound C (respectively for phosphatidylinositol 3-kinase [PI3K] or AMPK). The latter 3 also abolished VEGF induction of NO(*). These data indicate that AMPK and AKT are both downstream of PI3K and that AKT activation is partially dependent on AMPK. The interrelationship between AMPK and AKT, although known to be individually important in mediating VEGF activation of eNOS, is clearly characterized. Furthermore, AMPK/AKT/eNOS(s1179) was found downstream of a calpain/ezrin membrane interaction. These data no doubt provide new insights into the long mystified signaling gap between VEGF receptors and PI3K/AKT or AMPK-dependent eNOS activation. In view of the well-established significance of VEGF-dependent angiogenesis, these findings might have broad and important implications in cardiovascular pathophysiology.
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http://dx.doi.org/10.1161/CIRCRESAHA.108.178467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2720268PMC
January 2009

New synthetic thiocolchicine derivatives as lowtoxic anticancer agents.

Arch Pharm (Weinheim) 2005 Dec;338(12):582-9

Department of Chemistry, Seoul Women's University, Seoul, Korea.

New thiocolchicine derivatives (1-8) were designed as less toxic anticancer agents possessing the power full anticancer activity of colchicine. The synthesis and biological evaluation of these compounds were described. As a preliminary result of biological in vitro investigation, compounds 1, 6, and 7 showed lower toxicities than that of colchicine in combination with potent anticancer activities.
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http://dx.doi.org/10.1002/ardp.200500148DOI Listing
December 2005

Anti-hyperglycemic activity of Commelina communis L.: inhibition of alpha-glucosidase.

Diabetes Res Clin Pract 2004 Dec;66 Suppl 1:S149-55

Department of Biotechnology, College of Natural Sciences, Seoul Women's University, 126 GongReung-Dong, NoWon-Gu, Seoul 139-774, South Korea.

Since ages, botanical substances are in use for the remedy of diabetes with considerable degree of success. One of the such; an extract of Commelina communis L. (CE-L) after decoction in water has been traditionally used for the treatment of diabetes in Korea. However, its action mechanism has not yet been established. To explore the inside of its action-mechanism, in this study, the effect of the aqueous extract of C. communis L. (CE-L) on the activity of alpha-glucosidase was evaluated in vitro and in vivo. Aqueous extract of CE-L showed inhibitory activity of the alpha-glucosidase in a dose-dependent manner, in vitro. CE-L also seems to be by and large free from exerting any cytotoxic effect at least in CHO-K1 fibroblast and 3T3-L1 adipocyte. CE-L alleviated hyperglycemia caused by maltose or starch loading in normal and Streptozotocin (STZ)-induced diabetic mice with better efficacy than that of acarbose. In addition, prolonged administration of CE-L tends to normalize hyperglycemia in STZ-induced diabetic mice. Such results suggest that inhibitory activity of CE-L on alpha-glucosidase may contribute to delay in carbohydrate digestion and glucose absorption. Thus, CE-L has potential for use in the management of non-insulin-dependent diabetes.
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http://dx.doi.org/10.1016/j.diabres.2003.08.015DOI Listing
December 2004

Evaluation of the immune response following exposure of mice to bisphenol A: induction of Th1 cytokine and prolactin by BPA exposure in the mouse spleen cells.

Arch Pharm Res 2002 Dec;25(6):946-53

Department of Biology, The Graduate School, Seoul Women's University, 126 Gong Reung-2-Dong, NoWon-Gu, Seoul 139-774, Korea.

Bisphenol A [2, 2 bis (4-hydoxyphenyl) propane; BPA] is a widely used endocrine disruptors and has estrogenic activities. Although interests on biological effect of BPA are rising, evidences of its effect on immune system are lacking. We investigated that the effect of BPA on immune parameters to postulate the mechanism, and BPA interruptions between neuroendocrine and immune system. BPA was administrated to mice by p.o. (as a drinking water) dose on 0.015, 1.5 and 30 mg/ml for 4 weeks. The BPA treatment did not result in any change in body weight, spleen weight and distribution of lymphocyte subpopulation collected from spleen. BPA induced prolactin production in spleen, and exposure of BPA increased the activity of splenocyte proliferation in response to Con A (p<0.001). The production of a strong Th-1 type cytokine (IFN-gamma) was induced while Th-2 type (IL-4) was suppressed by BPA treatment. These were consistent with RT-PCR results of transcription factor GATA-3 and IRF-1. These findings suggested that stimulation of prolactin production by estrogenic effects of BPA would affect cytokine profiles, and lead to imbalanced cellular immune response. In addition, we could speculate that prolactin and cytokine is important mediator involved in network between neuroendocrine and immune system by BPA.
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http://dx.doi.org/10.1007/BF02977018DOI Listing
December 2002
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