Lipocalin-2 deficiency attenuates endothelial dysfunction associated with aging and obesity

Conference Theme: Emerging Therapies for an Aging Populatio

Identification and characterization of proteins interacting with SIRT1 and SIRT3: implications in the antiaging and metabolic effects of sirtuins

Sirtuins are a family of NAD+-dependent protein deacetylases that regulate cellular functions through deacetylation of a wide range of protein targets. Overexpression of Sir2,the first gene discovered in this family, is able to extend the life span in various organisms. The anti-aging effects of human homologues of sirtuins, SIRT1-7, have also been suggested by animal and human association studies. However, the precise mechanisms whereby sirtuins exert their anti-aging effects remain elusive. In this study, we aim to identify novel interacting partners of SIRT1 and SIRT3, two human sirtuins ubiquitously expressed in many tissue types. Our results demonstrate that SIRT1 and SIRT3 are localized within different intracellular compartments, mainly nuclei and mitochondria, respectively. Using affinity purification and MALDI-TOF/TOF-MS/MS analysis, their potential interacting partners have been identified from the enriched subcellular fractions and specific interactions confirmed by co-immunoprecipitation and Western blotting experiment. Further analyses suggest that overexpression of SIRT1 or SIRT3 in HEK293 cells could induce hypoacetylation and affect the intracellular localizations and protein stabilities of their interacting partners. Taken together, the present study has identified a number of novel SIRT protein interacting partners, which might be critically involved in the anti-aging and metabolic regulatory activities ofsirtuins. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.link_to_subscribed_fulltex

Lipocalin-2, an inflammatory adipokine, uncouples endothelial nitric-oxide synthase and enhances endothelial dysfunction caused by dietary obesity

Focused Conference Group: YI – Young Investigators’ Session: paper no. 2293Endothelial dysfunction contributes to the pathogenesis of cardiovascular diseases. Lipocalin-2 is a pro-inflammatory adipokine. Its circulating concentration positively associates with adiposity, dyslipidemia, hyperglycemia and insulin resistance. Lipocalin-2 deficiency protects mice from developing ageing- and obesity-induced insulin resistance. In the present study, endothelial function of wild type (WT) and lipocalin-2 knockout (Lcn2-KO) mice was compared by measuring isometric tensions in rings of aortae and carotid arteries from dietary obesity-challenged animals. High fat diet feeding for only three weeks significantly impaired endothelium-dependent relaxation (EDR) to insulin in aortae and enhanced endothelium-dependent contraction (EDC) to acetylcholine in carotid arteries. These endothelial dysfunctions were nearly abolished by lipocalin-2 deficiency. Insulin-induced Akt/eNOS phosphorylation was enhanced in aortae of Lcn2-KO mice. The increases in the ratio of eNOS monomers to dimers, and superoxide anion formation were significantly attenuated in mice without lipocalin-2. The level of nitrotyrosine in the total protein and precipitated eNOS of arteries from wide type mice was increased compared with that in Lcn2-KO vessels, despite a similar expression of eNOS protein. The basal and acetylcholine-stimulated superoxide anion production and COX-1 expression were diminished in Lcn2-KO arteries. Replacement with lipocalin-2 in Lcn2-KO mice time-dependently monomerized eNOS in the aorta, increased COX-1 expression levels, and impaired endothelial functions as demonstrated by reduced EDR and enhanced EDC. Lipocalin-2 plays a critical role in the development of obesity-induced endothelial dysfunction through modulation of eNOS activity and oxidative stress.The 16th World Congress on Basic and Clinical Pharmacology (WorldPharma2010), Copenhagen, Denmark, 17-23 July 2010. In Basic & Clinical Pharmacology & Toxicology, 2010, v. 107, suppl. 1, p. 159-16

Endothelium-dependent contractions induced by aging and diet-induced obesity are attenuated in lipocalin-2 deficient mice

AIM: Levels of Lipocalin-2, a pro-inflammatory adipokine, correlates with adiposity, dyslipidemia, hyperglycemia and insulin resistance. The present study evaluates vascular function in mice with deletion of the lipocalin-2 gene (Lcn2-KO). METHODS: Wild type (WT) and Lcn2-KO mice were fed with standard or high fat diet for 3–17 weeks. Intra-arterial blood pressure was measured. Isometric tension was measured in carotid artery rings with or without endothelium. Protein expression was measured by Western blotting. RESULTS: The obesity-induced increase in systolic blood pressure was attenuated in Lcn2-KO mice. In aged or obese WT mice, acetylcholine (ACh)-elicited endothelium-dependent contractions were abolished by the COX-1 selective inhibitor SC560 and the NADH oxidase inhibitor diphenylene iodonium. These contractions were attenuated in Lcn2-KO mice. ACh-stimulated superoxide anion production, COX-1 mRNA and protein expression were decreased in Lcn2-KO arteries. ACh-induced production of prostacyclins (PGI2) was lower in Lcn2-KO preparations. In aged or obese WT mice, PGI2 caused contractions in rings without endothelium but these contractions were reversed to relaxations in Lcn2-KO arteries. CONCLUSIONS: Lipocalin-2 plays an important role in obesity-induced hypertension and endothelial dysfunction through production of superoxide anions and COX-1 expression.The Experimental Biology 2010, Anaheim, CA., 24-28 April 2010. In The FASEB Journal, 2010, v. 24 Meeting abstract suppl., abstract no. 570.

Mice lacking lipocalin-2 are protected from developing insulin resistance associated with aging and obesity

The Conference abstracts' website is located at http://www.easd.org/index.php?option=com_content&view=article&id=69&Itemid=509Oral Session - OP 06 Inflammation, insulin action and type 2 diabetes: no. 31BACKGROUND AND AIMS: Obesity is characterized as a low-grade inflammation of the adipose tissue and increased circulating concentrations of pro-inflammatory cytokines. The “inflamed” adipose tissue can secrete a large amount of pro-inflammatory adipokines / cytokines that act as mediators for obesity-related metabolic syndrome. Previous studies have shown that the expression and production of lipocalin-2, a pro-inflammatory adipokine, are elevated in obese animal and human subjects. In this study, we aim to evaluate whether lipocalin-2 deficiency can protect the mice from developing systemic ...link_to_OA_fulltex

Gonadotropin secretion and pituitary responsiveness to GnRH in mares with granulosa-theca cell tumor

Granulosa-theca cell tumors (GTCTs) are able to secrete variable amounts of sex steroids and immunoreactive inhibin (ir-INH). Although the pituitary appears to be affected by the presence of a GTCT, pituitary responsiveness to exogenous GnRH has not been examined. The aims of the present study were to: (i) assess the plasma hormone concentrations of ir-INH, gonadotropins and sex steroids in eight mares with GTCT and (ii) assess the responsiveness of pituitary gonadotroph cells to exogenous GnRH stimulus both before and after tumor removal. In seven mares, the contralateral ovary was firm, small and inactive. Histopathological observations of the tumors confirmed the presumptive diagnosis of a GTCT. Four mares, judged to be in vernal transition period (n = 2) and in the breeding season (n = 2), were used as controls. A single intravenous injection of 40 mu g of GnRH agonist was given to each mare and blood samples were collected every 15 min from 2 h before to 4 h after injection. In four GTCT mares, this procedure was repeated 20 (n = 2) and 90 (n = 2) days after tumors removal. All plasma samples were analyzed for concentrations of ir-INH, LH, FSH, estradiol-17 beta (E-2) testosterone (T) by RIA and progesterone (P) by EIA. Results showed that E-2 levels were significantly higher (P < 0.001) in control animals compared to E-2 levels in GTCT mares before and after surgery. P and T concentrations were not statistically different between the groups. Baseline levels of ir-INH were greater (P < 0.05) in GTCT mares before surgery than in control mares, and decreased to undetectable levels after neoplasia ablation. Baseline FSH did not differ between control and GTCT animals either before or after the ovaries were removed. LH baseline values appeared to be higher for affected mares, but the difference was not statistically significant. Maximum release (MR) and area under the gonadotrophin release curve (AUC) after the GnRH challenge for both the gonadotrophins were similar between the groups. (c) 2006 Elsevier Inc. All rights reserved

Potentially toxic elements in solid waste streams : fate and management approaches

202308 bcchAccepted ManuscriptRGCPublishe

Lipocalin-2 deficiency prevents endothelial dysfunction associated with dietary obesity: Role of cytochrome P450 2C inhibition

Background and Purpose Lipocalin-2 is a pro-inflammatory adipokine up-regulated in obese human subjects and animal models. Its circulating levels are positively correlated with the unfavourable lipid profiles, elevated blood pressure and insulin resistance index. Augmented lipocalin-2 has been found in patients with cardiovascular abnormalities.The present study was designed to investigate the role of lipocalin-2 in regulating endothelial function and vascular reactivity. Experimental Approach Wild-type and lipocalin-2 knockout (Lcn2-KO) mice were fed with either a standard chow or a high-fat diet. Blood pressures and endothelium-dependent relaxations/contractions were monitored at 2 week intervals. Results Systolic blood pressure was elevated by high-fat diet in wild-type mice but not in Lcn2-KO mice. Endothelial dysfunction, reflected by the impaired endothelium-dependent relaxations to insulin and augmented endothelium-dependent contractions to ACh, was induced by high-fat diet in wild-type mice. In contrast, Lcn2-KO mice were largely protected from the deterioration of endothelial function caused by dietary challenges. The eNOS dimer/monomer ratio, NO bioavailability, basal and insulin-stimulated PKB/eNOS phosphorylation responses were higher in aortae of Lcn2-KO mice. Administration of lipocalin-2 attenuated endothelium-dependent relaxations to insulin and promoted endothelium-dependent contractions to ACh. It induced eNOS uncoupling and elevated COX expression in the arteries. Treatment with sulphaphenazole, a selective inhibitor of cytochrome P450 2C9, improved endothelial function in wild-type mice and blocked the effects of lipocalin-2 on both endothelium-dependent relaxations to insulin and endothelium-dependent contractions to ACh, as well as eNOS uncoupling. Conclusions Lipocalin-2, by modulating cytochrome P450 2C9 activity, is critically involved in diet-induced endothelial dysfunction. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.link_to_OA_fulltex