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ABSTRACT: The latest genome-wide association studies (GWAS) have re-energized our effort to understand the genetic basis of atherosclerotic cardiovascular disease. Although the knowledge generated by GWAS has confirmed that mediators of inflammation and perturbed lipid metabolism are major players in cardiovascular disease (CVD) development, much of individual disease heritability remains unexplained by the variants identified through GWAS. Moreover, results from interventions that aim at the pharmaceutical modification of lipid parameters fall short of expectation. These elusive treatment goals based on heritability studies highlight a key supportive, and perhaps even primary, role of nutritional therapy to achieve better health outcomes. Nonetheless, effective and specific interventions for CVD prevention using principles of "personalized" nutrition require a better knowledge of gene-diet interactions, an area that remains poorly explored. Dietary fatty acids such as omega-3 polyunsaturated fatty acids (PUFAs) are an excellent example of a widely studied "environment" that interacts with the genetic makeup in relation to CVD. A thorough exploration of the nutrigenomics and nutrigenetics of omega-3 PUFAs is key to understanding the etiology, and developing effective preventive measures. In this review, we will summarize the current state of knowledge of genetic interactions with omega-3 PUFAs in modulating lipid metabolism and inflammation, and defining health outcomes. Nutrigenetics and nutrigenomics are still in their infancy with respect to CVD prediction and therapy. Integration of the progress in the omics, including metabolomics, lipidomics, transcriptomics, and proteomics, coupled with advances in nutrigenomic and nutrigenetic research will move us towards personalized medicine as the ultimate paradigm of responsible clinical practice.
Current Atherosclerosis Reports 06/2013; 15(6):328. · 2.66 Impact Factor
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Hiroshi Urabe,
Hideto Kojima, Lawrence Chan,
Tomoya Terashima,
Nobuhiro Ogawa,
Miwako Katagi,
Kazunori Fujino,
Asako Kumagai,
Hiromichi Kawai,
Akihiro Asakawa,
Akio Inui,
Hitoshi Yasuda,
Yutaka Eguchi,
Kazuhiro Oka,
Hiroshi Maegawa,
Atsunori Kashiwagi,
Hiroshi Kimura
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ABSTRACT: Brain-derived neurotrophic factor (BDNF) suppresses food intake by acting on neurons in the hypothalamus. Here we show that BDNF-producing haematopoietic cells control appetite and energy balance by migrating to the hypothalamic paraventricular nucleus. These haematopoietic-derived paraventricular nucleus cells produce microglial markers and make direct contacts with neurons in response to feeding status. Mice with congenital BDNF deficiency, specifically in haematopoietic cells, develop hyperphagia, obesity and insulin resistance. These abnormalities are ameliorated by bone marrow transplantation with wild-type bone marrow cells. Furthermore, when injected into the third ventricle, wild-type bone marrow mononuclear cells home to the paraventricular nucleus and reverse the hyperphagia of BDNF-deficient mice. Our results suggest a novel mechanism of feeding control based on the production of BDNF by haematopoietic cells and highlight a potential new therapeutic route for the treatment of obesity.
Nature Communications 02/2013; 4:1526. · 7.40 Impact Factor
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ABSTRACT: Plin4 is a lipid droplet protein (LDP) found predominantly in white adipose tissue (WAT). The Plin4 gene is immediately downstream to Plin5 gene; the two genes exhibit distinct though overlapping tissue expression patterns. Plin4 is absent in brown adipose tissue (BAT) and liver and expressed at low levels in heart and skeletal muscle, whereas Plin5 is highly expressed in these oxidative tissues but at a low level in WAT. The physiological role of Plin4 remains unclear. We have generated Plin4(-/-) mice by gene targeting. Loss of Plin4 has no effect on body weight or composition, or on adipose mass or development. However, the triacylglycerol (TAG) content in heart, but not other oxidative tissues such as BAT, soleus muscle and liver, is markedly reduced in Plin4(-/-) mice. The heart of Plin4(-/-) mice display reduced Plin5 mRNA and protein levels (by ~38% and 87%, respectively, compared with wild-type) but unchanged mRNA levels of other perilipin family genes (Plin2 and Plin3) or genes involved in glucose and lipid metabolism. Despite reduced cardiac TAG level, both young and aged Plin4(-/-) mice maintain normal heart function as wild-type mice as measured by echocardiography. Interestingly, Plin4 deficiency prevents lipid accumulation in the heart that normally occurs after a prolonged (48h) fast. It also protects the heart from cardiac steatosis induced by high fat diet or when Plin4(-/-) mice are bred into Lep(-/-) obese background. In conclusion, inactivation of Plin4 downregulates Plin5 and reduces cardiac lipid accumulation in mice.
AJP Endocrinology and Metabolism 02/2013; · 4.75 Impact Factor
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ABSTRACT: Genome-wide association studies identified GLIS3 as a susceptibility locus for type 1 and type 2 diabetes. Global Glis3 deficiency in mice leads to congenital diabetes and neonatal lethality. In this study, we explore the role of Glis3 in adulthood using Glis3(+/-) and conditional knockout animals. We challenged Glis3(+/-) mice with high fat diet for 20 weeks and found that they developed diabetes because of impaired beta cell mass expansion. GLIS3 controls beta cell proliferation in response to high-fat feeding at least partly by regulating Ccnd2 transcription. To determine if sustained Glis3 expression is essential to normal beta cell function, we generated Glis3(fl/fl) /Pdx1Cre(ERT+) animal by intercrossing Glis3(fl/fl) mice with Pdx1Cre(ERT+) mice and used tamoxifen (TAM) to induce Glis3 deletion in adults. Adult Glis3(fl/fl) /Pdx1Cre(ERT+) mice are euglycaemic. TAM-mediated beta cell-specific inactivation of Glis3 in adult mice downregulates insulin expression, leading to hyperglycaemia and subsequently enhanced beta cell apoptosis. We conclude that normal Glis3 expression is required for pancreatic beta cell function and mass maintenance during adulthood, which impairment leads to diabetes in adults.
EMBO Molecular Medicine 11/2012; · 10.33 Impact Factor
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ABSTRACT: Several lines of evidence indicate that the effects of adipotide on weight loss and food consumption in obese monkeys are not due to a toxic effect, but rather result from the targeting mechanism of adipotide.
Science translational medicine 04/2012; 4(131):131lr2. · 7.80 Impact Factor
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ABSTRACT: Mutations in BSCL2 underlie human congenital generalized lipodystrophy. We inactivated Bscl2 in mice to examine the mechanisms whereby absence of Bscl2 leads to adipose tissue loss and metabolic disorders. Bscl2(-/-) mice develop severe lipodystrophy of white adipose tissue (WAT), dyslipidemia, insulin resistance, and hepatic steatosis. In vitro differentiation of both Bscl2(-/-) murine embryonic fibroblasts (MEFs) and stromal vascular cells (SVCs) reveals normal early-phase adipocyte differentiation but a striking failure in terminal differentiation due to unbridled cyclic AMP (cAMP)-dependent protein kinase A (PKA)-activated lipolysis, which leads to loss of lipid droplets and silencing of the expression of adipose tissue-specific transcription factors. Importantly, such defects in differentiation can be largely rescued by inhibitors of lipolysis but not by a gamma peroxisome proliferator-activated receptor (PPARγ) agonist. The residual epididymal WAT (EWAT) in Bscl2(-/-) mice displays enhanced lipolysis. It also assumes a "brown-like" phenotype with marked upregulation of UCP1 and other brown adipose tissue-specific markers. Together with decreased Pref1 but increased C/EBPβ levels, these changes highlight a possible increase in cAMP signaling that impairs terminal adipocyte differentiation in the EWAT of Bscl2(-/-) mice. Our study underscores the fundamental role of regulated cAMP/PKA-mediated lipolysis in adipose differentiation and identifies Bscl2 as a novel cell-autonomous determinant of activated lipolysis essential for terminal adipocyte differentiation.
Molecular and cellular biology 03/2012; 32(6):1099-111. · 6.06 Impact Factor
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ABSTRACT: Diabetic neuropathy is the most common diabetic complication. The pathogenetic pathways include oxidative stress, advanced glycation end product (AGE) formation, protein kinase C, and NF-κB activation, as well as increased polyol flux. These metabolic perturbations affect neurons, Schwann cells, and vasa nervorum, which are held to be the primary cell types involved. We hypothesize that diabetes induces the appearance of abnormal bone marrow-derived cells (BMDCs) that fuse with neurons in the dorsal root ganglia (DRG) of mice, leading to diabetic neuropathy. Neuronal poly(ADP-ribose) polymerase-1 (PARP-1) activation in diabetes is known to generate free radical and oxidant-induced injury and poly(ADP-ribose) polymer formation, resulting in neuronal death and dysfunction, culminating in neuropathy. We further hypothesize that BM-specific PARP expression plays a determining role in disease pathogenesis. Here we show that bone marrow transplantation (BMT) of PARP-knockout (PARPKO) cells to wild-type mice protects against, whereas BMT of wild-type cells to PARPKO mice, which are normally "neuropathy-resistant," confers susceptibility to, diabetic neuropathy. The pathogenetic process involving hyperglycemia, BMDCs, and BMDC-neuron fusion can be recapitulated in vitro. Incubation in high, but not low, glucose confers fusogenicity to BMDCs, which are characterized by proinsulin (PI) and TNF-α coexpression; coincubation of isolated DRG neurons with PI-BMDCs in high glucose leads to spontaneous fusion between the 2 cell types, while the presence of a PARP inhibitor or use of PARPKO BMDCs in the incubation protects against BMDC-neuron fusion. These complementary in vivo and in vitro experiments indicate that BMDC-PARP expression promotes diabetic neuropathy via BMDC-neuron fusion.
The FASEB Journal 01/2012; 26(1):295-308. · 5.71 Impact Factor
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Yoshinori Takemura,
Shinji Imai,
Hideto Kojima,
Miwako Katagi,
Isamu Yamakawa,
Toshiyuki Kasahara,
Hiroshi Urabe,
Tomoya Terashima,
Hitoshi Yasuda, Lawrence Chan,
Hiroshi Kimura,
Yoshitaka Matsusue
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ABSTRACT: Brain-derived neurotrophic factor (BDNF) stimulates peripheral nerve regeneration. However, the origin of BNDF and its precise effect on nerve repair have not been clarified. In this study, we examined the role of BDNF from bone marrow-derived cells (BMDCs) in post-injury nerve repair. Control and heterozygote BDNF knockout mice (BDNF+/-) received a left sciatic nerve crush using a cerebral blood clip. Especially, for the evaluation of BDNF from BMDCs, studies with bone marrow transplantation (BMT) were performed before the injury. We evaluated nerve function using a rotarod test, sciatic function index (SFI), and motor nerve conduction velocity (MNCV) simultaneously with histological nerve analyses by immunohistochemistry before and after the nerve injury until 8 weeks. BDNF production was examined by immunohistochemistry and mRNA analyses. After the nerve crush, the controls showed severe nerve dysfunction evaluated at 1 week. However, nerve function was gradually restored and reached normal levels by 8 weeks. By immunohistochemistry, BDNF expression was very faint before injury, but was dramatically increased after injury at 1 week in the distal segment from the crush site. BDNF expression was mainly co-localized with CD45 in BMDCs, which was further confirmed by the appearance of GFP-positive cells in the BMT study. Variant analysis of BDNF mRNA also confirmed this finding. BDNF+/- mice showed a loss of function with delayed histological recovery and BDNF+/+→BDNF+/- BMT mice showed complete recovery both functionally and histologically. These results suggested that the attenuated recovery of the BDNF+/- mice was rescued by the transplantation of BMCs and that BDNF from BMDCs has an essential role in nerve repair.
PLoS ONE 01/2012; 7(9):e44592. · 4.09 Impact Factor
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ABSTRACT: Insulin and proinsulin are normally produced only by the pancreas and thymus. We detected in diabetic rodents the presence of extra pancreatic proinsulin-producing bone marrow-derived cells (PI-BMDCs) in the BM, liver, and fat. In mice and rats with diabetic neuropathy, we also found proinsulin-producing cells in the sciatic nerve and neurons of the dorsal root ganglion (DRG). BM transplantation experiments using genetically marked donor and recipient mice showed that the proinsulin-producing cells in the DRG, which morphologically resemble neurons, are actually polyploid proinsulin-producing fusion cells formed between neurons and PI-BMDCs. Additional experiments indicate that diabetic neuropathy is not simply the result of nerve cells being damaged directly by hyperglycemia. Rather, hyperglycemia induces fusogenic PI-BMDCs that travel to the peripheral nervous system, where they fuse with Schwann cells and DRG neurons, causing neuronal dysfunction and death, the sine qua non for diabetic neuropathy. Poorly controlled diabetes is indeed bad to the bone.
Annals of the New York Academy of Sciences 12/2011; 1240:70-6. · 3.15 Impact Factor
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Kirstin F Barnhart,
Dawn R Christianson,
Patrick W Hanley,
Wouter H P Driessen,
Bruce J Bernacky,
Wallace B Baze,
Sijin Wen,
Mei Tian,
Jingfei Ma,
Mikhail G Kolonin,
Pradip K Saha,
Kim-Anh Do,
James F Hulvat,
Juri G Gelovani, Lawrence Chan,
Wadih Arap,
Renata Pasqualini
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ABSTRACT: Obesity, defined as body mass index greater than 30, is a leading cause of morbidity and mortality and a financial burden worldwide. Despite significant efforts in the past decade, very few drugs have been successfully developed for the treatment of obese patients. Biological differences between rodents and primates are a major hurdle for translation of anti-obesity strategies either discovered or developed in rodents into effective human therapeutics. Here, we evaluate the ligand-directed peptidomimetic CKGGRAKDC-GG-(D)(KLAKLAK)(2) (henceforth termed adipotide) in obese Old World monkeys. Treatment with adipotide induced targeted apoptosis within blood vessels of white adipose tissue and resulted in rapid weight loss and improved insulin resistance in obese monkeys. Magnetic resonance imaging and dual-energy x-ray absorptiometry confirmed a marked reduction in white adipose tissue. At experimentally determined optimal doses, monkeys from three different species displayed predictable and reversible changes in renal proximal tubule function. Together, these data in primates establish adipotide as a prototype in a new class of candidate drugs that may be useful for treating obesity in humans.
Science translational medicine 11/2011; 3(108):108ra112. · 7.80 Impact Factor
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Ligen Lin,
Pradip K. Saha,
Xiaojun Ma,
Iyabo O. Henshaw,
Longjiang Shao,
Benny H. J. Chang,
Eric D. Buras,
Qiang Tong, Lawrence Chan,
Owen P. McGuinness,
Yuxiang Sun
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ABSTRACT: Aging is associated with increased adiposity in white adipose tissues and impaired thermogenesis in brown adipose tissues; both contribute to increased incidences of obesity and type 2 diabetes. Ghrelin is the only known circulating orexigenic hormone that promotes adiposity. In this study, we show that ablation of the ghrelin receptor (growth hormone secretagogue receptor, GHS-R) improves insulin sensitivity during aging. Compared to wild-type (WT) mice, old Ghsr−/− mice have reduced fat and preserve a healthier lipid profile. Old Ghsr−/− mice also exhibit elevated energy expenditure and resting metabolic rate, yet have similar food intake and locomotor activity. While GHS-R expression in white and brown adipose tissues was below the detectable level in the young mice, GHS-R expression was readily detectable in visceral white fat and interscapular brown fat of the old mice. Gene expression profiles reveal that Ghsr ablation reduced glucose/lipid uptake and lipogenesis in white adipose tissues but increased thermogenic capacity in brown adipose tissues. Ghsr ablation prevents age-associated decline in thermogenic gene expression of uncoupling protein 1 (UCP1). Cell culture studies in brown adipocytes further demonstrate that ghrelin suppresses the expression of adipogenic and thermogenic genes, while GHS-R antagonist abolishes ghrelin’s effects and increases UCP1 expression. Hence, GHS-R plays an important role in thermogenic impairment during aging. Ghsr ablation improves aging-associated obesity and insulin resistance by reducing adiposity and increasing thermogenesis. Growth hormone secretagogue receptor antagonists may be a new means of combating obesity by shifting the energy balance from obesogenesis to thermogenesis.
Aging cell 10/2011; 10(6):996 - 1010. · 7.55 Impact Factor
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ABSTRACT: A reduction in low density lipoprotein (LDL) cholesterol or an increase in high density lipoprotein (HDL) cholesterol can reduce the risk of development of atherosclerosis through overlapping or independent mechanisms. However, the clinical outcome of combined therapy remains in debate. In this study, we first characterized effects of various constructs of helper-dependent adenoviral vector (HDAd) expressing apolipoprotein E3 or LDL receptor (LDLR) in vivo on plasma cholesterol levels. Using this information, we designed experiments and compared the effects of long-term (28 weeks) LDL cholesterol lowering or raising HDL cholesterol, or a combination of both on advanced atherosclerosis in Ldlr(-/-) mice, a mouse model of familial hypercholesterolemia. Our major findings are: (i) various factors influence in vivo functional activity, which appear to be context dependent; (ii) apolipoprotein AI (APOAI) gene transfer, which raises HDL cholesterol, retards progression of atherosclerosis but does not induce regression; (iii) LDLR or LDLR and APOAI combination gene therapy induces lesion regression; however, LDLR gene transfer accounts for the majority of the effects of combined gene therapy; (iv) LDLR gene therapy reduces interleukin-7, which is a master regulator of T-cell homeostasis, but APOAI gene therapy does not. These results indicate that LDL cholesterol lowering is effective and sufficient in protection against atherosclerosis and induction of regression of pre-existing atherosclerosis.
Journal of genetic syndrome & gene therapy. 09/2011; 2:106.
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Isamu Yamakawa,
Hideto Kojima,
Tomoya Terashima,
Miwako Katagi,
Jiro Oi,
Hiroshi Urabe,
Mitsuru Sanada,
Hiromichi Kawai, Lawrence Chan,
Hitoshi Yasuda,
Hiroshi Maegawa,
Hiroshi Kimura
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ABSTRACT: Tumor necrosis factor (TNF)-α is a potent proinflammatory cytokine involved in the pathogenesis of diabetic neuropathy. We inactivated TNF-α to determine if it is a valid therapeutic target for the treatment of diabetic neuropathy. We effected the inactivation in diabetic neuropathy using two approaches: by genetic inactivation of TNF-α (TNF-α(-/-) mice) or by neutralization of TNF-α protein using the monoclonal antibody infliximab. We induced diabetes using streptozotocin in wild-type and TNF-α(-/-) mice. We measured serum TNF-α concentration and the level of TNF-α mRNA in the dorsal root ganglion (DRG) and evaluated nerve function by a combination of motor (MNCV) and sensory (SNCV) nerve conduction velocities and tail flick test, as well as cytological analysis of intraepidermal nerve fiber density (IENFD) and immunostaining of DRG for NF-κB p65 serine-276 phosphorylated and cleaved caspase-3. Compared with nondiabetic mice, TNF-α(+/+) diabetic mice displayed significant impairments of MNCV, SNCV, tail flick test, and IENFD as well as increased expression of NF-κB p65 and cleaved caspase-3 in their DRG. In contrast, although nondiabetic TNF-α(-/-) mice showed mild abnormalities of IENFD under basal conditions, diabetic TNF-α(-/-) mice showed no evidence of abnormal nerve function tests compared with nondiabetic mice. A single injection of infliximab in diabetic TNF-α(+/+) mice led to suppression of the increased serum TNF-α and amelioration of the electrophysiological and biochemical deficits for at least 4 wk. Moreover, the increased TNF-α mRNA expression in diabetic DRG was also attenuated by infliximab, suggesting infliximab's effects may involve the local suppression of TNF-α. Infliximab, an agent currently in clinical use, is effective in targeting TNF-α action and expression and amelioration of diabetic neuropathy in mice.
AJP Endocrinology and Metabolism 08/2011; 301(5):E844-52. · 4.75 Impact Factor
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Rongying Li,
Antoni Paul,
Kerry W S Ko,
Michael Sheldon,
Benjamin E Rich,
Tomoya Terashima,
Carrie Dieker,
Shelley Cormier,
Lan Li,
Elie A Nour, Lawrence Chan,
Kazuhiro Oka
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ABSTRACT: Aims Interleukin-7 (IL-7) is a master regulator of T-cell development and homoeostasis. Increased IL-7 levels are associated with inflammatory diseases. The aims of this study were to determine whether IL-7 is a biomarker for inflammatory conditions or an active participant in atherogenesis. Methods and results Advanced atherosclerotic lesions in Apoe(-/-) mice were regressed by long-term cholesterol lowering through treatment with a helper-dependent adenovirus expressing apolipoprotein E (n= 6-10). Using this model, gene expression patterns in the aorta were analysed at an early phase of regression by microarray. After stringent statistical analysis, we found that IL-7 expression is significantly reduced in response to lowering of cholesterol (n= 6). To understand the importance of IL-7 down-regulation for atherosclerotic regression, we studied the effects and mechanisms of action of IL-7 on endothelial cells (ECs) in vitro as well as in vivo. Our major findings are: (i) IL-7 up-regulates cell adhesion molecules and monocyte chemoattractant protein-1 in ECs and promotes monocyte adhesion to ECs; (ii) this regulation is mediated by phosphatidylinositol 3-kinase (PI3K)/AKT-dependent and -independent activation of NF-κB; (iii) elevation of plasma IL-7 induces recruitment of monocytes/macrophages to endothelium without affecting plasma cholesterol (n= 5, 6); and (4) lack of IL-7 in bone marrow-derived cells reduces migration of monocytes/macrophages to the lesions (n= 5, 6). Conclusion These results suggest that IL-7 inflames endothelium via PI3K/AKT-dependent and -independent activation of NF-κB and recruits monocytes/macrophages to the endothelium, thus playing an active role in atherogenesis.
European Heart Journal 07/2011; · 10.48 Impact Factor
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ABSTRACT: Interstitial cells of Cajal (ICCs), which express c-Kit receptor tyrosine kinase (KIT), play an important role in gastrointestinal motility. Loss of ICCs likely contributes to diabetic gastrointestinal motility disorder, however, the mechanism of attrition remains unknown. Here, we test the hypothesis that the bone marrow-derived progenitors are an important source of intestinal ICCs and that decreased homing of these progenitors in diabetes contributes to ICC diminution.
Wild type mice were X-ray irradiated, transplanted with bone marrow (BMT) from green fluorescence protein (GFP)-transgenic (TG)-mice and subsequently made diabetic by streptozotocin (STZ) injection. Intestinal homing of GFP-positive bone marrow-derived cells was examined 2 or 5 months after STZ treatment.
In the BMT-mice, we found many GFP-positive bone marrow-derived cells (BMDCs) in most parts of the intestinal area, the number of BMDCs was significantly decreased in diabetic mice compared with nondiabetic controls. As a representative area, we further examined the myenteric plexus of the proximal small intestine, and found that the cell numbers of ICCs marked by c-Kit-positive immunoreactivity were decreased by more than 40% in diabetic versus nondiabetic mice. Furthermore, numbers of c-Kit+/GFP+ and c-Kit+/GFP- cells were similar in nondiabetic mice, and decreased by 45.8% and 42.0%, respectively, in diabetic mice.
These results suggest that the decreased homing from the bone marrow is a major cause of ICC loss in the intestine in diabetes mellitus.
Journal of Gastroenterology and Hepatology 01/2011; 26(6):1072-8. · 2.87 Impact Factor
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ABSTRACT: Pro-resolving and anti-inflammatory mediator products of murine 12/15-lipoxygenase (LOX) exhibit potent actions on vascular inflammation and protect against the progression of atherosclerosis. The present study was designed to determine whether augmenting dietary lipids modulates the body's endogenous anti-inflammatory pro-resolving mechanisms and promotes atherosclerosis.
We investigated the biometabolic consequences of variations in lipid mediator biosynthesis using genetic knockout and overexpression models of 12/15-LOX mice fed the commonly used 'Western diet'. Unexpectedly, this high-fat diet annulled the protective actions of 12/15-LOX, and the combination of a Western diet and 12/15-LOX overexpression paradoxically promoted inflammation leading to production of diet-related and 12/15-LOX-dependent blood mediators that differentially activated endothelial cells via expression of ICAM-1. Hyperlipidemia not only affected the biosynthesis of lipoxin A4, a key pro-resolving mediator, but also disrupted the protective pro-resolving function of 12/15-LOX products, and the enzyme pathway no longer protected against atherosclerosis in vivo.
We uncovered a novel mechanism whereby a high-fat diet as well as hyperlipidemia disrupt the homeostasis of inflammation resolution. These findings underscore the importance of dietary essential PUFAs and LOX-derived lipid mediators in combination with lipid-lowering agents in the prevention and treatment of atherosclerotic cardiovascular diseases.
Journal of Nutrigenetics and Nutrigenomics 01/2011; 4(1):12-24. · 1.14 Impact Factor
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Atul R Chopra,
Ramakrishna Kommagani,
Pradip Saha,
Jean-Francois Louet,
Christina Salazar,
Junghun Song,
Jaewook Jeong,
Milton Finegold,
Benoit Viollet,
Franco DeMayo, Lawrence Chan,
David D Moore,
Bert W O'Malley
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ABSTRACT: All organisms have devised strategies to counteract energy depletion and promote fitness for survival. We show here that cellular energy depletion puts into play a surprising strategy that leads to absorption of exogenous fuel for energy repletion. The energy-depletion-sensing kinase AMPK binds, phosphorylates, and activates the transcriptional coactivator SRC-2, which in a liver-specific manner promotes absorption of dietary fat from the gut. Hepatocyte-specific deletion of SRC-2 results in intestinal fat malabsorption and attenuated entry of fat into the blood stream. This defect can be attributed to AMPK- and SRC-2-mediated transcriptional regulation of hepatic bile acid (BA) secretion into the gut, as it can be completely rescued by replenishing intestinal BA or by genetically restoring the levels of hepatic bile salt export pump (BSEP). Our results position the hepatic AMPK-SRC-2 axis as an energy rheostat, which upon cellular energy depletion resets whole-body energy by promoting absorption of dietary fuel.
Cell metabolism 01/2011; 13(1):35-43. · 17.35 Impact Factor
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ABSTRACT: The triterpenoid, 2-Cyano-3,12-dioxooleana-1,9-dien-28-oic-acid (CDDO), and its methyl ester, CDDO-Me, are undergoing clinical
trials in cancer and leukemia therapy. Here we report that CDDO-Me ameliorates diabetes in high fat diet-fed type 2 diabetic
mice, and in Leprdb/db mice. CDDO-Me reduces proinflammatory cytokine expression in these animals. Oral CDDO-Me administration reduces total body,
plasma triglyceride, and free fatty acid levels. It also improves glucose tolerance and insulin tolerance tests. Its potent
glucose-lowering activity results from enhanced insulin action. Hyperinsulinemic-euglycemic clamp experiments reveal an increased
glucose infusion rate required to maintain euglycemia and showed significant increase in muscle-specific insulin-stimulated
glucose uptake (71% soleus, 58% gastronomies) and peripheral glucose clearance as documented by 48% increase in glucose disposal
rate. CDDO-Me activates AMP-activated protein kinase (AMPK) and via LKB1 activation in muscle and liver in vivo. Treatment
of isolated primary hepatocytes with CDDO-Me directly stimulates AMPK activity and LKB1 phosphorylation and decreases acetyl-coA
carboxylase (ACC) activity; it also downregulates lipogenic gene expression, suppresses gluconeogenesis and increases glucose
uptake. Inhibition of AMPK phosphorylation using compound C and lentiviral-mediated knockdown of AMPK completely blocks the
CDDO-Me induced effect on hepatocytes as well as C2C12 cells. We conclude that the triterpenoid CDDO-Me has potent anti-diabetic action in diabetic mouse models that is mediated
at least in part through AMPK activation. The in vivo anti-diabetogenic effects occur at a dose substantially lower than that
used for anti-leukemia therapy. We suggest that CDDO-Me holds promise as a potential anti-diabetic agent.
Journal of Biological Chemistry 10/2010; · 4.77 Impact Factor
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Hepatology 10/2010; · 11.66 Impact Factor
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ABSTRACT: The triterpenoid 2-Cyano-3,12-dioxooleana-1,9-dien-28-oic-acid (CDDO) and its methyl ester (CDDO-Me) are undergoing clinical trials in cancer and leukemia therapy. Here we report that CDDO-Me ameliorates diabetes in high fat diet-fed type 2 diabetic mice and in Lepr(db/db) mice. CDDO-Me reduces proinflammatory cytokine expression in these animals. Oral CDDO-Me administration reduces total body fat, plasma triglyceride, and free fatty acid levels. It also improves glucose tolerance and insulin tolerance tests. Its potent glucose-lowering activity results from enhanced insulin action. Hyperinsulinemic-euglycemic clamp reveals an increased glucose infusion rate required to maintain euglycemia and showed a significant increase in muscle-specific insulin-stimulated glucose uptake (71% soleus, 58% gastrocnemius) and peripheral glucose clearance as documented by a 48% increase in glucose disposal rate. CDDO-Me activates AMP-activated protein kinase (AMPK) and via LKB1 activation in muscle and liver in vivo. Treatment of isolated hepatocytes with CDDO-Me directly stimulates AMPK activity and LKB1 phosphorylation and decreases acetyl-coA carboxylase activity; it also down-regulates lipogenic gene expression, suppresses gluconeogenesis, and increases glucose uptake. Inhibition of AMPK phosphorylation using compound C and lentiviral-mediated knockdown of AMPK completely blocks the CDDO-Me-induced effect on hepatocytes as well as C(2)C(12) cells. We conclude that the triterpenoid CDDO-Me has potent anti-diabetic action in diabetic mouse models that is mediated at least in part through AMPK activation. The in vivo anti-diabetogenic effects occur at a dose substantially lower than that used for anti-leukemia therapy. We suggest that CDDO-Me holds promise as a potential anti-diabetic agent.
Journal of Biological Chemistry 10/2010; 285(52):40581-92. · 4.77 Impact Factor
