Liu, G (George)
Comparison of Brown and White Adipose Tissue Fat Fractions in ob, seipin and Fsp27 Gene Knockout Mice by Chemical Shift Selective Imaging and 1H MR Spectroscopy.
Xin-Gui Peng, Shenghong Ju, Fang Fang, Yu Wang, Ke Fang, Xin Cui, George Liu, Peng Li, Hui Mao, Gao-Jun Teng
1Zhong-Da Hospital, Southeast University.
Brown adipose tissue (BAT) plays a key role in thermogenesis to protect the body from cold and obesity. White adipose tissue (WAT) stores excess energy in the form of triglycerides. To better understand the genetic effect on regulation of WAT and BAT, we investigated the fat fraction (FF) in two types of adipose tissues in ob/ob, human BSCL2/seipin gene knock-out (SKO), Fsp27 gene knock-out (Fsp27-/-), and wild type (WT) mice in vivo using chemical shift selective imaging and (1)H MR spectroscopy. We reported that the visceral fat volume in WAT was significantly larger in ob/ob mice, but visceral fat volumes were lower in SKO and Fsp27-/- mice compared to WT mice. BAT FF was significantly higher in ob/ob mice than WT group and similar to that of WAT. In contrast, WAT FFs in SKO and Fsp27-/- mice were lower and similar to that of BAT. The adipocyte size of WAT in ob/ob mice and the BAT adipocyte size in ob/ob, SKO, and Fsp27 mice were significantly larger compared to WT mice. However, the WAT adipocyte size was significantly smaller in SKO mice than WT mice. Positive correlations were observed between the adipocyte size and FFs of WAT and BAT. These results suggested that smaller adipocyte size correlates with lower FFs of WAT and BAT. In addition, the differences of FFs in WAT and BAT measured by MR methods in different mouse models were related to the different regulation effects of ob, seipin or Fsp27 gene on developing WAT and BAT.
PLoS One. 2012 ;7 (11):e48530 23133640
Diabetic HDL Is Dysfunctional in Stimulating Endothelial Cell Migration and Proliferation Due to Down Regulation of SR-BI Expression.
Bing Pan, Yijing Ma, Hui Ren, Yubin He, Yongyu Wang, Xiaofeng Lv, Donghui Liu, Liang Ji, Baoqi Yu, Yuhui Wang, Y Eugene Chen, Subramaniam Pennathur, Jonathan D Smith, George Liu, Lemin Zheng
The Institute of Cardiovascular Sciences, Ministry of Education, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Peking University Health Science Center, Beijing, China ; Institute of Systems Biomedicine, School of Basic Medical Sciences, Ministry of Education, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Peking University Health Science Center, Beijing, China ; Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Peking University Health Science Center, Beijing, China.
BACKGROUND: Diabetic HDL had diminished capacity to stimulate endothelial cell (EC) proliferation, migration, and adhesion to extracellular matrix. The mechanism of such dysfunction is poorly understood and we therefore sought to determine the mechanistic features of diabetic HDL dysfunction. METHODOLOGY/PRINCIPAL FINDINGS: We found that the dysfunction of diabetic HDL on human umbilical vein endothelial cells (HUVECs) was associated with the down regulation of the HDL receptor protein, SR-BI. Akt-phosphorylation in HUVECs was induced in a biphasic manner by normal HDL. While diabetic HDL induced Akt phosphorylation normally after 20 minutes, the phosphorylation observed 24 hours after diabetic HDL treatment was reduced. To determine the role of SR-BI down regulation on diminished EC responses of diabetic HDL, Mouse aortic endothelial cells (MAECs) were isolated from wild type and SR-BI (-/-) mice, and treated with normal and diabetic HDL. The proliferative and migratory effects of normal HDL on wild type MAECs were greatly diminished in SR-BI (-/-) cells. In contrast, response to diabetic HDL was impaired in both types suggesting diminished effectiveness of diabetic HDL on EC proliferation and migration might be due to the down regulation of SR-BI. Additionally, SR-BI down regulation diminishes diabetic HDL's capacity to activate Akt chronically. CONCLUSIONS/SIGNIFICANCE: Diabetic HDL was dysfunctional in promoting EC proliferation, migration, and adhesion to matrix which was associated with the down-regulation of SR-BI. Additionally, SR-BI down regulation diminishes diabetic HDL's capacity to activate Akt chronically.
Most cited papers:
Doppler optical cardiogram gated 2D color flow imaging at 1000 fps and 4D in vivo visualization of embryonic heart at 45 fps on a swept source OCT system.
Adrian Mariampillai, Beau A Standish, Nigel R Munce, Cristina Randall, George Liu, James Y Jiang, Alex E Cable, I A Vitkin, Victor X D Yang
We report a Doppler optical cardiogram gating technique for increasing the effective frame rate of Doppler optical coherence tomography (DOCT) when imaging periodic motion as found in the cardiovascular system of embryos. This was accomplished with a Thorlabs swept-source DOCT system that simultaneously acquired and displayed structural and Doppler images at 12 frames per second (fps). The gating technique allowed for ultra-high speed visualization of the blood flow pattern in the developing hearts of African clawed frog embryos (Xenopus laevis) at up to 1000 fps. In addition, four-dimensional (three spatial dimensions + temporal) Doppler imaging at 45 fps was demonstrated using this gating technique, producing detailed visualization of the complex cardiac motion and hemodynamics in a beating heart.
Overexpression of lipoprotein lipase in transgenic Watanabe heritable hyperlipidemic rabbits improves hyperlipidemia and obesity.
Tomonari Koike, Jingyan Liang, Xiaofei Wang, Tomonaga Ichikawa, Masashi Shiomi, George Liu, Huijun Sun, Shuji Kitajima, Masatoshi Morimoto, Teruo Watanabe, Nobuhiro Yamada, Jianglin Fan
Cardiovascular Disease Laboratory, Department of Pathology, Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba 305-8575, Japan.
Lipoprotein lipase (LPL) is the rate-limiting enzyme for the hydrolysis of the triglyceride-rich lipoproteins and plays a critical role in lipoprotein and free fatty acid metabolism. Genetic manipulation of LPL may be beneficial in the treatment of hypertriglyceridemias, but it is unknown whether increased LPL activity may be effective in lowering plasma cholesterol and improving insulin resistance in familial hypercholesterolemic patients. To test the hypothesis that stimulation of LPL expression may be used as an adjunctive therapy for treatment of homozygous familial hypercholesterolemia, we have generated transgenic (Tg) Watanabe heritable hyperlipidemic (WHHL) rabbits that overexpress the human LPL transgene and compared their plasma lipid levels, glucose metabolism, and body fat accumulation with those of non-Tg WHHL rabbits. Overexpression of LPL dramatically ameliorated hypertriglyceridemia in Tg WHHL rabbits. Furthermore, increased LPL activity in male Tg WHHL rabbits also corrected hypercholesterolemia (544 +/- 52 in non-Tg versus 227 +/- 29 mg/dl in Tg, p < 0.01) and reduced body fat accumulation by 61%(323 +/- 27 in non-Tg versus 125 +/- 21ginTg, p < 0.01), suggesting that LPL plays an important role in mediating plasma cholesterol homeostasis and adipose accumulation. In addition, overexpression of LPL significantly suppressed high fat diet-induced obesity and insulin resistance in Tg WHHL rabbits. These results imply that systemic elevation of LPL expression may be potentially useful for the treatment of hyperlipidemias, obesity, and insulin resistance.
Spontaneous atherosclerosis in aged lipoprotein lipase-deficient mice with severe hypertriglyceridemia on a normal chow diet.
Xiaohong Zhang, Rong Qi, Xunde Xian, Fei Yang, Michael Blackstein, Xuming Deng, Jianglin Fan, Colin Ross, Joanna Karasinska, Michael R Hayden, George Liu
Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiovascular Sciences, Peking University, Beijing, China.
Large-scale epidemiological studies have revealed a strong association between hypertriglyceridemia and coronary arteriosclerotic disease. However, there are conflicting reports whether the severe hypertriglyceridemia caused by lipoprotein lipase (LPL) deficiency is pro- or antiatherogenic. To determine the effect of LPL deficiency on atherosclerosis, we pursued long-term observation of the development of atherosclerotic lesions in an LPL gene deficient mouse model. At 4 months of age, homozygous LPL-deficient mice exhibited severe hypertriglyceridemia but no signs of aortic atherosclerotic lesions. At >15 months of age, these mice developed foam cell-rich atherosclerotic lesions at the aortic root, whereas wild-type and heterozygous mice were lesion-free at the same age. Further investigation revealed that plasma malondialdehyde levels in >15-month-old LPL-deficient mice were significantly higher than those of heterozygous and wild-type mice. Electron spin resonance analysis showed a marked increase in oxidative susceptibility of chylomicrons from the aged LPL-deficient mice. Incubation of chylomicrons from >15-month-old LPL-deficient mice with cultured human umbilical vein endothelial cells showed significantly increased upregulation of vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1, markers of enhanced endothelial activation, and enhanced adherence of human THP-1 mononuclear cells. These results clearly demonstrate the occurrence of spontaneous atherosclerosis in aged LPL-deficient mice mediated by the oxidation of chylomicrons and the activation of vascular endothelial cells.
Jizhen Lin, Yasuhiro Tsuboi, Frank Rimell, George Liu, Katsuhiro Toyama, Hirokazu Kawano, Michael M Paparella, Samuel B Ho
Department of Otolaryngology, Otitis Media Research Center, University of Minnesota School of Medicine, Minneapolis, MN 55455, USA. email@example.com
A hallmark of mucoid otitis media (MOM, i.e., chronic otitis media with mucoid effusion) is mucus accumulation in the middle ear cavity, a condition that impairs transduction of sounds in the ear and causes hearing loss. The mucin identities of mucus and the underlying mechanism for the production of mucins in MOM are poorly understood. In this study, we demonstrated that the MUC5B and MUC4 were major mucins in MOM that formed distinct treelike polymers (mucus strands). The MUC5B and MUC4 mRNAs in the middle ear mucosa with MOM were up regulated 5-fold and 6-fold, compared with the controls. This upregulation was accompanied by the extensive proliferation of the MUC5B- and MUC4-producing cells in the middle ear epithelium. Further study indicated that the mucin hyperproduction was significantly linked to CD4+ and CD8+ T cells and/or CD68+ monocyte macrophages. It suggests that MUC5B and MUC4 expression may be regulated by the products of these cells.
Rong Qi, Yu Gao, Yin Tang, Rui-Rui He, Tao-Le Liu, Yun He, Sheng Sun, Bo-Yu Li, Yang-Bing Li, George Liu
Peking University Institute of Cardiovascular Sciences, Peking University Health Science Center, Peking University, Beijing, China. firstname.lastname@example.org
Generations 5 and 6 (G5 and G6) poly(amidoamine)(PAMAM) dendrimers have been shown to be highly efficient nonviral carriers in in vitro gene delivery. However, their high toxicity and unsatisfied in vivo efficacy limit their applications. In this study, to improve their characteristics as gene delivery carriers, polyethylene glycol (PEG, molecular weight 5,000) was conjugated to G5 and G6 PAMAM dendrimers (PEG-PAMAM) at three different molar ratios of 4%, 8%, and 15%(PEG to surface amine per PAMAM dendrimer molecular). Compared with unconjugated PAMAM dendrimers, PEG conjugation significantly decreased the in vitro and in vivo cytotoxicities and hemolysis of G5 and G6 dendrimers, especially at higher PEG molar ratios. Among all of the PEG-PAMAM dendrimers, 8% PEG-conjugated G5 and G6 dendrimers (G5-8% PEG, G6-8% PEG) resulted in the most efficient muscular gene expression when polyplexes were injected intramuscularly to the quadriceps of neonatal mice. Consistent with the in vivo results, these two 8% PEG-conjugated PAMAM dendrimers could also mediate the highest in vitro transfection in 293A cells. Therefore, G5-8% PEG and G6-8% PEG possess a great potential for gene delivery both in vivo and in vitro.
Application of high-resolution skeletal imaging to measurements of volumetric BMD and skeletal microarchitecture in Chinese-American and white women: explanation of a paradox.
Columbia University, College of Physicians and Surgeons, New York, New York, USA. email@example.com
Asian women have lower rates of hip and forearm fractures despite lower areal BMD (aBMD) by DXA compared with white women and other racial groups. We hypothesized that the lower fracture rates may be explained by more favorable measurements of volumetric BMD (vBMD) and microarchitectural properties, despite lower areal BMD. To address this hypothesis, we used high-resolution pQCT (HRpQCT), a new method that can provide this information noninvasively. We studied 63 premenopausal Chinese-American (n = 31) and white (n = 32) women with DXA and HRpQCT. aBMD by DXA did not differ between groups for the lumbar spine (1.017 +/- 0.108 versus 1.028 +/- 0.152 g/cm(2); p = 0.7), total hip (0.910 +/- 0.093 versus 0.932 +/- 0.134 g/cm(2); p = 0.5), femoral neck (0.788 +/- 0.083 versus 0.809 +/- 0.129 g/cm(2); p = 0.4), or one-third radius (0.691 +/- 0.052 versus 0.708 +/- 0.047 g/cm(2); p = 0.2). HRpQCT at the radius indicated greater trabecular (168 +/- 41 versus 137 +/- 33 mg HA/cm(3); p =<0.01) and cortical (963 +/- 46 versus 915 +/- 42 mg HA/cm(3); p < 0.0001) density; trabecular bone to tissue volume (0.140 +/- 0.034 versus 0.114 +/- 0.028; p =<0.01); trabecular (0.075 +/- 0.013 versus 0.062 +/- 0.009 mm; p < 0.0001) and cortical thickness (0.98 +/- 0.16 versus 0.80 +/- 0.14 mm; p < 0.0001); and lower total bone area (197 +/- 34 versus 232 +/- 33 mm(2); p =<0.001) in the Chinese versus white women and no difference in trabecular number, spacing, or inhomogeneity before adjustment for covariates. Similar results were observed at the weight-bearing tibia. At the radius, adjustment for covariates did not change the direction or significance of differences except for bone, which became similar between the groups. However, at the tibia, adjustment for covariates attenuated differences in cortical BMD and bone area and accentuated differences in trabecular microarchitecture such that Chinese women additionally had higher trabecular number and lower trabecular spacing, as well as inhomogeneity after adjustment. Using the high-resolution technology, the results provide a mechanistic explanation for why Chinese women have fewer hip and forearm fractures than white women.
Increased plasma HDL cholesterol levels and biliary cholesterol excretion in hamster by LCAT overexpression.
Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiology, Ministry of Education, Peking University, 38 Xue Yuan Road, Beijing 100083, PR China.
Lecithin cholesterol acyltransferase (LCAT) is a key enzyme in the metabolism of high density lipoprotein (HDL), which has been found inversely correlated with atherosclerosis. Adenovirus mediated overexpression of human LCAT (hLCAT) in hamsters resulted in increased levels of plasma total cholesterol, HDL cholesterol, phospholipids and enlarged particle size of HDL. It also increased cholesterol and total bile acid concentrations in bile. Hepatic mRNA level of cholesterol 7alpha-hydroxylase increased 2.7-fold in hamsters. However, such effects were not observed in mice in a parallel experiment. This study suggests that overexpression of hLCAT in hamsters facilitated reverse cholesterol transport. Similar metabolic changes in humans might modify atherogenic risk.
Bret Cooper, Anil Neelam, Kimberly B Campbell, Joohyun Lee, George Liu, Wesley M Garrett, Brian Scheffler, Mark L Tucker
Soybean Genomics and Improvement Laboratory, 10300 Baltimore Ave., Bldg. 006 Rm 213, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Beltsville, MD 20705, USA. firstname.lastname@example.org
Uromyces appendiculatus is a rust fungus that causes disease on beans. To understand more about the biology of U. appendiculatus, we have used multidimensional protein identification technology to survey proteins in germinating asexual uredospores and have compared this data with proteins discovered in an inactive spore. The relative concentrations of proteins were estimated by counting the numbers of tandem mass spectra assigned to peptides for each detected protein. After germination, there were few changes in amounts of accumulated proteins involved in glycolysis, acetyl Co-A metabolism, citric acid cycle, ATP-coupled proton transport, or gluconeogenesis. Moreover, the total amount of translation elongation factors remained high, supporting a prior model that suggests that germlings acquire protein translation machinery from uredospores. However, germlings contained a higher amount of proteins involved in mitochondrial ADP:ATP translocation, which is indicative of increased energy production. Also, there were more accumulating histone proteins, pointing to the reorganization of the nuclei that occurs after germination prior to appressorium formation. Generally, these changes are indicative of metabolic transition from dormancy to germination and are supported by cytological and developmental models of germling growth.
Localized vessel expression of lipoprotein lipase in rabbits leads to rapid lipid deposition in the balloon-injured arterial wall.
Institute of Cardiovascular Sciences, Peking University Health Science Center, 38 XueYuan Road, HaiDian District, Beijing 100083, China.
Recent studies on mice demonstrated that lipoprotein lipase (LPL) located in the arterial wall might play a pro-atherogenic role. There are major differences between humans and mice in lipoprotein metabolism and in susceptibility to atherosclerosis. We have therefore used rabbits fed normal chow diet as a model to assess such localized effects by adenovirus-mediated gene transfer of human catalytically active wild type LPL (hLPLwt) and an inactive mutant (hLPL194) to balloon-injured carotid arteries. By morphometric analysis on cryosections stained with Oil Red O (ORO) we found 7- and 4-fold increases, respectively, of lipid deposition in the arterial walls 7 days after infection with adenovirus expressing hLPLwt or hLPL194, when compared with a virus expressing human alkaline phosphatase (hAP) as control. Macrophages were detected in the arteries expressing both forms of LPL, but apoB was only found in arteries expressing hLPLwt. Expression of the LPL gene products was transient and was gone after 2 weeks, but the accumulated lipid deposits remained between the neointimal and the media layers even after 8 weeks. Our data demonstrate that expression of LPL in the arterial wall (with or without lipase activity) leads to lipid accumulation in balloon-injured rabbit arteries, and could result in enhanced formation of atherosclerotic lesions.
Expression of LPL in endothelial-intact artery results in lipid deposition and vascular cell adhesion molecule-1 upregulation in both LPL and ApoE-deficient mice.
Jinyu Wang, Xunde Xian, Wei Huang, Li Chen, Liling Wu, Yi Zhu, Jianglin Fan, Colin Ross, Michael R Hayden, George Liu
Institute of Cardiovascular Sciences, Peking University Health Science Center, 38 Xueyuan Road, Hai Dian District, 100083, Beijing, China.
OBJECTIVE Overexpression of lipoprotein lipase (LPL) in deendothelialized artery led to profound localized lipid deposition. In this study the role of LPL in atherogenesis in endothelial-intact carotid arteries was assessed in genetically hyperlipidemic LPL- and ApoE-deficient mice. METHODS AND RESULTS Human wild-type LPL (hLPLwt), catalytically inactive LPL (hLPL194), or control alkaline phosphatase (hAP) were expressed in endothelial-intact carotid arteries via adenoviral vectors. Compared with Ad-hAP, lipid deposition in the arterial wall increased 10.0- and 5.1-fold for Ad-hLPLwt and Ad-hLPL194 in LPL-deficient mice, and 10.6- and 6.2-fold in ApoE-deficient mice, respectively. Vascular cell adhesion molecule-1 (VCAM-1) was upregulated in Ad-hLPLwt and Ad-hLPL194 transferred arteries. CONCLUSIONS Endothelial cell associated LPL, either active or inactive, in the arterial wall is a strong proatherosclerotic factor in both LPL- and ApoE-deficient mice.