[show abstract][hide abstract] ABSTRACT: Obese states characterized by chronic inflammation are closely linked to the development of metabolic dysfunction. We identified adipolin/CTRP12 as an insulin-sensitizing and anti-inflammatory adipokine. Although obese conditions down-regulate adipolin expression, its molecular mechanism is largely unknown. Here we show that the transcriptional regulator Krüppel-like factor (KLF) 15 is involved in the regulation of adipolin expression in adipocytes. White adipose tissue from diet-induced obese (DIO) mice showed decreased expression of KLF9 and KLF15 among several KLFs, which was accompanied by reduced expression of adipolin. In cultured 3T3L1 adipocytes, treatment with TNFα significantly reduced the mRNA levels of KLF9, KLF15 and adipolin. Adenovirus-mediated overexpression of KLF15 but not KLF9 reversed TNFα-induced reduction of adipolin expression in adipocytes. Conversely, gene targeting ablation of KLF15 attenuated adipolin expression in adipocytes. Expression of KLF15 but not KLF9 enhanced the promoter activity of adipolin in HEK293 cells. Pretreatment of 3T3L1 adipocytes with the JNK inhibitor SP600125, but not p38 MAPK inhibitor SB203580 blocked the inhibitory effects of TNFα on adipolin and KLF15 expression. These data suggest that adipose inflammation under conditions of obesity suppresses adipolin expression via JNK-dependent down-regulation of KLF15 in adipocytes.
PLoS ONE 01/2013; 8(12):e83183. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Obesity is linked with an increased risk of lymphedema, which is a serious clinical problem. Adiponectin is a circulating adipokine that is down-regulated in obese states. We investigated the effects of adiponectin on lymphatic vessel formation in a model of lymphedema and dissected its mechanisms.
A mouse model of lymphedema was created via ablation of tail surface lymphatic network. Adiponectin-knockout mice showed the greater diameter of the injured tail compared with wild-type mice, which was associated with lower numbers of lymphatic endothelial cells (LECs). Systemic delivery of adiponectin reduced the thickness of the injured tail and enhanced LEC formation in wild-type and adiponectin-knockout mice. Adiponectin administration also improved the edema of injured tails in obese KKAy mice. Treatment with adiponectin protein stimulated the differentiation of human LECs into tubelike structures and increased LEC viability. Adiponectin treatment promoted the phosphorylation of AMP-activated protein kinase (AMPK), Akt, and endothelial nitric oxide synthase n LECs. Blockade of AMPK or Akt activity abolished adiponectin-stimulated increase in LEC differentiation and viability and endothelial nitric oxide synthase phosphorylation. Inhibition of AMPK activation also suppressed adiponectin-induced Akt phosphorylation in LECs. In contrast, inactivation of Akt signaling had no effects on adiponectin-mediated AMPK phosphorylation in LECs. Furthermore, adiponectin administration did not affect the thickening of the damaged tail in endothelial nitric oxide synthase-knockout mice.
Adiponectin can promote lymphatic vessel formation via activation of AMPK/Akt/endothelial nitric oxide synthase signaling within LECs, thereby leading to amelioration of lymphedema.
Journal of the American Heart Association. 01/2013; 2(5):e000438.
[show abstract][hide abstract] ABSTRACT: Obesity is highly associated with the development of insulin resistance and type 2 diabetes. Recently we found that adipolin/CRTP12 is an adipocytokine that exerts beneficial actions on glucose metabolism. Here we investigated the regulation of circulating adipolin under conditions of obesity and assessed its potential mechanisms. Both full and cleaved forms of adipolin were observed in mouse plasma. Diet-induced obese (DIO) mice showed a significant reduction of plasma levels of full and total (full and cleaved) adipolin compared with control mice, resulting in an increase in the ratio of cleaved to full isoform. In vitro gene transfection studies using HEK293 cells revealed that a deletion mutant of adipolin gene (Δaa90-93) caused a reduction of cleaved production of adipolin in media. A bioinformatics analysis of adipolin amino acid sequence indicated the potential involvement of the family of proprotein convertases (PCs) in cleavage of adipolin. Treatment of 3T3-L1 adipocytes with an inhibitor for PCs abolished the expression of cleaved adipolin form in the media. The expression of furin, the member of PCs, was increased in adipose tissue of DIO mice. Furin expression was also increased in cultured adipocytes by treatment with an inducer of inflammation. These data suggest that obesity states facilitate the cleavage of adipolin presumably through upregulation of furin in adipose tissue.
Biochemical and Biophysical Research Communications 10/2012; · 2.41 Impact Factor
[show abstract][hide abstract] ABSTRACT: Obesity is closely associated with the progression of vascular disorders, including atherosclerosis and postangioplasty restenosis. C1q/TNF-related protein (CTRP) 9 is an adipocytokine that is down-regulated in obese mice. Here we investigated whether CTRP9 modulates neointimal hyperplasia and vascular smooth muscle cell (VSMC) proliferation in vivo and in vitro. Left femoral arteries of wild-type (WT) mice were injured by a steel wire. An adenoviral vector expressing CTRP9 (Ad-CTRP9) or β-galactosidase as a control was intravenously injected into WT mice 3 d before vascular injury. Delivery of Ad-CTRP9 significantly attenuated the neointimal thickening and the number of bromodeoxyuridine-positive proliferating cells in the injured arteries compared with that of control. Treatment of VSMCs with CTRP9 protein attenuated the proliferative and chemotactic activities induced by growth factors including platelet-derived growth factor (PDGF)-BB, and suppressed PDGF-BB-stimulated phosphorylation of ERK. CTRP9 treatment dose-dependently increased cAMP levels in VSMCs. Blockade of cAMP-PKA pathway reversed the inhibitory effect of CTRP9 on DNA synthesis and ERK phosphorylation in response to PDGF-BB. The present data indicate that CTRP9 functions to attenuate neointimal formation following vascular injury through its ability to inhibit VSMC growth via cAMP-dependent mechanism, suggesting that the therapeutic approaches to enhance CTRP9 production could be valuable for prevention of vascular restenosis after angioplasty.-Uemura, Y., Shibata, R., Ohashi, K., Enomoto, T., Kambara, T., Yamamoto, T., Ogura, Y., Yuasa, D., Joki, Y., Matsuo, K., Miyabe, M., Kataoka, Y., Murohara, T., Ouchi, N. Adipose-derived factor CTRP9 attenuates vascular smooth muscle cell proliferation and neointimal formation.
[show abstract][hide abstract] ABSTRACT: Acute coronary syndrome is a leading cause of death in developed countries. Follistatin-like 1 (FSTL1) is a myocyte-derived secreted protein that is upregulated in the heart in response to ischemic insult. Here, we investigated the therapeutic impact of FSTL1 on acute cardiac injury in small and large preclinical animal models of ischemia/reperfusion and dissected its molecular mechanism.
Administration of human FSTL1 protein significantly attenuated myocardial infarct size in a mouse or pig model of ischemia/reperfusion, which was associated with a reduction of apoptosis and inflammatory responses in the ischemic heart. Administration of FSTL1 enhanced the phosphorylation of AMP-activated protein kinase in the ischemia/reperfusion-injured heart. In cultured cardiac myocytes, FSTL1 suppressed apoptosis in response to hypoxia/reoxygenation and lipopolysaccharide-stimulated expression of proinflammatory genes through its ability to activate AMP-activated protein kinase. Ischemia/reperfusion led to enhancement of bone morphogenetic protein-4 expression and Smad1/5/8 phosphorylation in the heart, and FSTL1 suppressed the increased phosphorylation of Smad1/5/8 in ischemic myocardium. Treating cardiac myocytes with FSTL1 abolished the bone morphogenetic protein-4-stimulated increase in apoptosis, Smad1/5/8 phosphorylation, and proinflammatory gene expression. In cultured macrophages, FSTL1 diminished lipopolysaccharide-stimulated expression of proinflammatory genes via activation of AMP-activated protein kinase and abolished bone morphogenetic protein-4-dependent induction of proinflammatory mediators.
Our data indicate that FSTL1 can prevent myocardial ischemia/reperfusion injury by inhibiting apoptosis and inflammatory response through modulation of AMP-activated protein kinase- and bone morphogenetic protein-4-dependent mechanisms, suggesting that FSTL1 could represent a novel therapeutic target for post-myocardial infarction, acute coronary syndrome.
[show abstract][hide abstract] ABSTRACT: Ischemic heart disease is the major cause of death in Western countries. CTRP9 (C1q/TNF-related protein 9) is a fat-derived plasma protein that has salutary effects on glucose metabolism and vascular function. However, the functional role of CTRP9 in ischemic heart disease has not been clarified. Here, we examined the regulation of CTRP9 in response to acute cardiac injury and investigated whether CTRP9 modulates cardiac damage after ischemia and reperfusion. Myocardial ischemia-reperfusion injury resulted in reduced plasma CTRP9 levels and increased plasma free fatty acid levels, which were accompanied by a decrease in CTRP9 expression and an increase in NADPH oxidase component expression in fat tissue. Treatment of cultured adipocytes with palmitic acid or hydrogen peroxide reduced CTRP9 expression. Systemic administration of CTRP9 to wild-type mice, before the induction of ischemia or at the time of reperfusion, led to a reduction in myocardial infarct size following ischemia-reperfusion. Administration of CTRP9 also attenuated myocyte apoptosis in ischemic heart, which was accompanied by increased phosphorylation of AMP-activated protein kinase (AMPK). Treatment of cardiac myocytes with CTRP9 protein reduced apoptosis in response to hypoxia/reoxygenation and stimulated AMPK phosphorylation. Blockade of AMPK activity reversed the suppressive actions of CTRP9 on cardiomyocyte apoptosis. Knockdown of adiponectin receptor 1 diminished CTRP9-induced increases in AMPK phosphorylation and survival of cardiac myocytes. Our data suggest that CTRP9 protects against acute cardiac injury following ischemia-reperfusion via an AMPK-dependent mechanism.
Journal of Biological Chemistry 04/2012; 287(23):18965-73. · 4.65 Impact Factor