The purpose of this study was to test a hypothesis that T3 promotes glucose uptake via enhancing insulin-induced Akt phosphorylation and VAMP2 translocation in 3T3-L1 adipocytes. T3 significantly enhanced insulin-induced phosphorylation of Akt, cytoplasma to cell membrane translocations of vesicle-associated membrane protein 2 (VAMP2) and glucose transporter 4 (GLUT4), and glucose uptake in adipocytes. Akt inhibitor X abolished the promoting effects of T3, suggesting that Akt activation is essential for T3 to enhance these insulin-induced events in adipocytes. Knockdown of VAMP2 using siRNA abrogated the effects of T3 on insulin-induced GLUT4 translocation and glucose uptake, suggesting that VAMP2 is an important mediator of these processes. Conclusions - These data suggest that T3 may promote glucose uptake via enhancing insulin-induced phosphorylation of Akt and subsequent translocations of VAMP2 and GLUT4 in 3T3-L1 adipocytes. Akt phosphorylation is necessary for the promoting effects of T3 on insulin-stimulated VAMP2 translocation. Further, VAMP2 is essential for T3 to increase insulin-stimulated translocation of GLUT4 and subsequent uptake of glucose in adipocytes.
GLUT4; RNAi; T3; Akt; VAMP2
The purpose of this study was to determine changes in klotho, endothelin (ET) receptors, and superoxide production in kidneys of aged rats and whether these changes are exacerbated in aged rats with cognitive impairment. Twenty aged rats (male, 27 months) were divided into an Old Impaired group (n = 9) and an Old Intact group (n = 11) according to a cognitive function test. A group of 12-month-old rats (n = 10) was used as a Young Intact group. Serum creatinine was increased significantly in the Old Impaired group, suggesting impaired renal function. Aged rats showed glomerulosclerosis and tubulointerstitialfibrosis. These pathological changes were markedly aggravated in the old cognitively impaired than in the old cognitively intact animals. Notably, aged rats demonstrated a significant decrease in klotho protein expression in renal cortex and medulla. Protein expression of IL-6, Nox2, ETa receptors and superoxide production were increased whereas mitochondrial SOD (MnSOD) and ETb receptors expression were decreased in kidneys of the aged rats. Interestingly, these changes were more pronounced in the old impaired than in the old intact rats. In conclusion, the aging-related kidney damage was exacerbated in aged rats with cognitive impairment. Klotho, ETB, and MnSOD were downregulated but ETa, IL-6, Nox2, and superoxide production were upregulated in the aging-related kidney damage. These changes were more pronounced in rats with cognitive impairment.
Aging; Klotho; Glomerusclerosis; ET receptor; Superoxide; Interleukin-6
Background & Hypothesis
IL-10 is an anti-inflammatory cytokine. Nox1 is a mitogenic oxidase (p65-mox). The objective of this study was to test a hypothesis that IL10 deficiency would cause vascular remodeling via the upregulation of Nox1.
Methods & Results
Recombinant AAV carrying short hairpin small interference RNA for Nox1 (AAV.Nox1shRNA) was constructed for in vivo specific inhibition of Nox1. Three groups of IL10 gene knockout (IL10KO) mice and 3 groups of wild-type (WT) mice were used. Three groups of each strain received intravenous delivery of AAV.Nox1shRNA, AAV.ScrambledshRNA, and PBS, respectively. Animals were euthanized at 3 weeks after gene delivery. IL10KO increased Nox1 protein expression, NADPH oxidase activity, and superoxide production in aortas. IL10KO also resulted in a significant decrease in aortic medial thickness, a loss of smooth muscle cells, and an increase in vascular collagen deposition, indicating vascular remodeling. The IL10KO-induced increases in NADPH oxidase activity and superoxide production and vascular remodeling were abolished by silencing of p65-mox, suggesting that these effects may be mediated by the upregulation of Nox1. In addition, IL10KO increased endothelin-1 (ET-1) levels in plasma and aortas, and this effect was partially blocked by silencing of Nox1. RNAi silencing of Nox1 obliterated the IL10KO-induced increases in IL-6 expression in aortas, superoxide production and MMP-9 activity in aortic smooth muscle cells (SMC), and SMC migration.
IL10 is essential to the maintenance of normal vasculature as IL10 deficiency resulted in vascular damage and remodeling. The IL10KO-induced vascular structure damage may be mediated by the up-regulation of Nox1.
vascular remodeling; vascular smooth muscle cell; AAV; IL-6; MMP-9; ET-1; NADPH oxidase; superoxide
The purpose of this study was to determine the role of the pro-inflammatory cytokine IL-6 in cold-induced hypertension (CIH). Four groups of male Sprague Dawley rats were used (6 rats/group). After blood pressure (BP) was stabilized, 3 groups received intravenous delivery of AAV carrying IL-6shRNA, AAV carrying scrambled shRNA (ScrshRNA), and phosphate buffered solution (PBS), respectively, prior exposure to a cold environment (5°C). The last group received PBS and was kept at room temperature (25°C, warm) as a control. AAV delivery of IL-6shRNA significantly attenuated cold-induced elevation of systolic BP and kept it at the control level for up to 7 weeks (length of the study). Chronic exposure to cold up-regulated IL-6 expression in aorta, heart and kidneys and increased macrophage and T-cell infiltration in kidneys, suggesting that cold exposure increases inflammation. IL-6shRNA delivery abolished the cold-induced up-regulation of IL-6, indicating effective silence of IL-6. Interestingly, RNAi knockdown of IL-6 prevented cold-induced inflammation as evidenced by a complete inhibition of TNF-α expression and leukocyte infiltration by IL-6shRNA. RNAi knockdown of IL-6 significantly decreased the cold-induced increase in vascular superoxide production. It is noted that IL-6shRNA abolished the cold-induced increase in collagen deposition in the heart, suggesting that inflammation is involved in cold-induced cardiac remodeling. Cold exposure caused glomerular collapses which could be prevented by knockdown of IL-6, suggesting an important role of inflammation in cold-induced renal damage. Conclusions: Cold exposure increased IL-6 expression and inflammation which play a critical role in the pathogenesis of CIH and cardiac and renal damage.
cold exposure; inflammation; interleukin-6; short-hairpin siRNA; RNAi; adeno-associated virus
Pulmonary arterial hypertension (PAH) is a chronic and progressive disease characterized by a persistent elevation of pulmonary artery pressure accompanied by right ventricular hypertrophy (RVH). The current treatment for pulmonary hypertension is limited and only provides symptomatic relief due to unknown etiology and pathogenesis of the disease. Both vasoconstriction and structural remodeling (enhanced proliferation of VSMC) of the pulmonary arteries contribute to the progressive course of PAH, irrespective of different underlying causes. The exact molecular mechanism of PAH, however, is not fully understood. The purpose of this review is to provide recent advances in the mechanistic investigation of PAH. Specifically, this review focuses on nitric oxide (NO), oxidative stress and inflammation and how these factors contribute to the development and progression of PAH. This review also discusses recent and potential therapeutic advancements for the treatment of PAH.
pulmonary arterial hypertension; pulmonary arterial remodeling; nitric oxide; cGMP; oxidative stress; NADPH oxidase; inflammation; cytokines; chemokines
Thyroid hormone (T3) can stimulate protein synthesis and cell growth. NOX1 is a mitogenic oxidase. The aim of this study was to test a novel hypothesis that T3 induces artery smooth muscle cell proliferation by up-regulating NOX1.
Methods and Results
Immunofluoresence confocal microscopy was used to visualize the sub-cellular localization of NOX1 and TRα1 in rat aorta smooth muscle (RASM) cells. Optical sectioning showed that TRα1 and NOX1 co-localized around the nucleus. T3 promoted RASM cell proliferation as determined by the fact that T3 significantly increased the number of cytokinesis cells, proliferating cellular nuclear antigen (PCNA), and smooth muscle α-actin (SM α-actin). T3 increased NOX1 expression at both the transcription (mRNA) and translation (protein) levels as evaluated by RT-PCR and western blot, respectively. T3 also significantly increased the intracellular ROS production based on the oxidation of 2’,7’-dichlorodihydrofluoresein (H2DCF) to a fluorescent 2’,7’-dichlorofluoresein (DCF). RNAi silence of TRα1 or NOX1 abolished T3-induced intracellular ROS generation and PCNA and SM α-actin expression, indicating that TRα1 and NOX1 mediated T3-induced RASM cell proliferation. Notably, RNAi silence of TRα1 blocked the T3-induced increase in NOX1 expression whereas silence of NOX1 did not affect TRα1 expression, disclosing a new pathway, i.e., T3-TRα1-NOX1-cell proliferation.
TRα1 and NOX1 co-localized around the nucleus. T3 induced RASM cell proliferation by up-regulating NOX1 in a TRα1-dependent manner.
thyroid hormone; TRα1; NOX1; ROS; smooth muscle cell; proliferation
The prevalence of hypertension is increased in winter and in cold regions of the world. Cold temperatures make hypertension worse and trigger cardiovascular complications (stroke, myocardial infarction, heart failure, etc.). Chronic or intermittent exposure to cold causes hypertension and cardiac hypertrophy in animals. The purpose of this review is to provide the recent advances in the mechanistic investigation of cold-induced hypertension (CIH). Cold temperatures increase the activities of the sympathetic nervous system (SNS) and the renin-angiotensin system (RAS). The SNS initiates CIH via the RAS. Cold exposure suppresses the expression of eNOS and formation of NO, increases the production of endothelin-1 (ET-1), up-regulates ETA receptors, but down-regulates ETB receptors. The roles of these factors and their relations in CIH will be reviewed.
cold-induced hypertension; cold-induced cardiac hypertrophy; cold; blood pressure; sympathetic nervous system; renin-angiotensin system; endothelin; mineralocorticoid receptor; eNOS; c-myc
Type 2 diabetes mellitus (T2DM) affects a large population worldwide. T2DM is a complex heterogeneous group of metabolic disorders including hyperglycemia and impaired insulin action and/or insulin secretion. T2DM causes dysfunctions in multiple organs or tissues. Current theories of T2DM include a defect in insulin-mediated glucose uptake in muscle, a dysfunction of the pancreatic β-cells, a disruption of secretory function of adipocytes, and an impaired insulin action in liver. The etiology of human T2DM is multifactorial, with genetic background and physical inactivity as two critical components. The pathogenesis of T2DM is not fully understood. Animal models of T2DM have been proved to be useful to study the pathogenesis of, and to find a new therapy for, the disease. Although different animal models share similar characteristics, each mimics a specific aspect of genetic, endocrine, metabolic, and morphologic changes that occur in human T2DM. The purpose of this review is to provide the recent progress and current theories in T2DM and to summarize animal models for studying the pathogenesis of the disease.
Klotho is a recently discovered antiaging gene. The objective of this study was to test the hypothesis that klotho gene delivery attenuates the progression of spontaneous hypertension and renal damage in spontaneous hypertensive rats (SHRs). An adeno-associated virus (AAV) carrying mouse klotho full-length cDNA (AAV.mKL) was constructed for in vivo expression of klotho. Four groups of male SHRs and 1 group of sex- and age-matched Wistar-Kyoto rats (5 rats per group) were used. Blood pressure was measured twice in all of the animals before gene delivery. Four groups of SHRs received an IV injection of AAV.mKL, AAV.LacZ, AAV.GFP, and PBS, respectively. The Wistar-Kyoto group received PBS and served as a control. AAV.mKL stopped the further increase in blood pressure in SHRs, whereas blood pressures continued to increase in other SHR groups. One single dose of AAV.mKL prevented the progression of spontaneous hypertension for at least 12 weeks (length of the study). Klotho expression and production were suppressed in SHRs, which were reverted by AAV.mKL. AAV.mKL increased plasma interleukin 10 levels but decreased Nox2 expression, NADPH oxidase activity, and superoxide production in kidneys and aortas in SHRs. AAV.mKL abolished renal tubular atrophy and dilation, tubular deposition of proteinaceous material, glomerular collapse, and collagen deposition seen in SHRs, indicating that klotho gene delivery attenuated renal damage. Therefore, the suppressed klotho expression may play a role in the progression of spontaneous hypertension and renal damage in SHRs. AAV delivery of klotho may offer a new approach for the long-term control of hypertension and for renoprotection.
klotho; Nox2; blood pressure; adeno-associated virus; renoprotection
Klotho is a new anti-aging gene. Genetic mutation of klotho causes multiple premature aging-like phenotypes and strikingly shortens lifespan. Overexpression of the klotho gene in mice suppresses aging and extends lifespan which may involve the mechanism of suppression of insulin signaling and oxidant stress. Klotho functions as a cofactor/coreceptor regulating fibroblast growth factor (FGF) 23 signaling. Klotho acts as a glucuronidase and activates ion channel TRPV5. Klotho protects against endothelial dysfunction and regulates the production of nitric oxide. Klotho also influences intracellular signaling pathways including p53/p21, cAMP, protein kinase C (PKC) and Wnt signaling pathways. The discovery of klotho has a great impact on aging research. The purpose of this review is to provide the recent progress and future directions of klotho research. Specifically, this review will cover: klotho and aging, structure and expression of the klotho gene, localization of klotho expression, source of circulating klotho, current understanding of klotho functions, and signaling pathways of klotho.
klotho; aging; insulin signaling; fibroblast growth factor; glucuronidase; vitamin D
Molecular cardiology is a new and fast-growing area of cardiovascular medicine that aims to apply molecular biology techniques for the mechanistic investigation, diagnosis, prevention and treatment of cardiovascular disease. As an emerging discipline, it has changed conceptual thinking of cardiovascular development, disease etiology and pathophysiology. Although molecular cardiology is still at a very early stage, it has opened a promising avenue for understanding and controlling cardiovascular disease. With the rapid development and application of molecular biology techniques, scientists and clinicians are closer to curing heart diseases that were thought to be incurable 20 years ago. There clearly is a need for a more thorough understanding of the molecular mechanisms of cardiovascular diseases to promote the advancement of stem cell therapy and gene therapy for heart diseases. The present paper briefly reviews the state-of-the-art techniques in the following areas of molecular cardiology: gene analysis in the diseased heart; transgenic techniques in cardiac research; gene transfer and gene therapy for cardiovascular disease; and stem cell therapy for cardiovascular disease.
DNA; Genes; Heart diseases; Hypertrophy; Molecular biology; Myocardial infarction