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Agarwal VR, Bhatia D, Joshi A, Mishra P, Bharadwaj KG, lobo AS, Menon P, Dhar P, Pandey P, Srinivasa S, sonawane V. Abstract 4521: P7170, a novel inhibitor of phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) and activin receptor-like kinase 1 (ALK1) shows anti-tumor activity in triple negative breast cancer. Cancer Res 2014. [DOI: 10.1158/1538-7445.am2014-4521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Triple negative breast cancer (TNBC) lacks ER, PR and Her2 receptor expression & accounts for nearly 10-15% of all breast cancer. It is an aggressive disease with high risk for early relapse & visceral metastasis leading to poor survival as compared to other subtypes. Currently, there is no targeted therapy beyond cytotoxic chemotherapy for TNBC. PI3K-mTOR pathway is often dysregulated (via mutations in PI3K or PTEN) in TNBC and hence offers an opportunity to develop a therapeutic to address the high unmet medical need in this disease. P7170, a small molecule mTOR/PI3K/ALK1 inhibitor with potent antitumor activity in various cancer types {Cancer Res, April 15,2012; 72(8 Supplement): 3742 and 3759} is currently undergoing Phase 1 clinical trial. Here, we report the evaluation of anti-tumor activity and the identification of potential pharmacodynamic markers of P7170 in a TNBC model. P7170 inhibited proliferation (IC50 range 5 - 38 nmol/L) in TNBC cell lines as determined using propidium iodide (PI) assay. In addition, P7170 inhibited anchorage-independent growth of tumor cells isolated from patient derived tumor xenografts evaluated in a clonogenic assay. PI3K-mTOR pathway proteins pS6 and p4EBP1 were potently inhibited whereas pAkt was modestly inhibited by P7170 in MDA-MB-231 cells as assessed by Western blot. It also inhibited migration of MDA-MB-231 cells in a transwell migration assay. P7170 at 1/3rd dose of Maximum tolerated dose (5 mg/kg, po) as a single agent resulted in 63% (P<0.05) tumor growth inhibition in MDA-MB-231 xenograft mouse model. Pharmacodynamic effects of P7170 were evaluated in the plasma, tumor and skin of MDA-MB-231 tumor bearing mice treated with
P7170 (5 and 15 mg/kg) orally for 3 days. Expression of target genes was measured by qRT-PCR, tumor and skin proteins were measured by immunohistochemistry, and plasma proteins by ELISA. P7170 significantly reduced pS6 protein in a dose-and time-dependent manner in the tumor and skin. P7170 significantly reduced tumor p4EBP1 protein at the highest dose and reduced tumor CDC25A gene by 2-fold. In addition, P7170 dose-dependently reduced plasma IGF1/IGFBP3 ratios compared to vehicle group. Conclusion: These data suggest that P7170 demonstrates robust antiproliferative activities in vitro and anti-tumor activity in vivo in TNBC. Tumor pS6 protein, CDC25A transcript levels and skin pS6 levels were identified as pharmacodynamic markers of P7170 activity. P7170 could be a therapeutic option for TNBC patients, and warrants testing in a clinical trial.
Citation Format: Veena R. Agarwal, Dimple Bhatia, Asavari Joshi, Prabha Mishra, Kalyani G. Bharadwaj, Aurelio S. lobo, Pranoy Menon, Payal Dhar, Prashant Pandey, Sreesha Srinivasa, vinay sonawane. P7170, a novel inhibitor of phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) and activin receptor-like kinase 1 (ALK1) shows anti-tumor activity in triple negative breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4521. doi:10.1158/1538-7445.AM2014-4521
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Khan RS, Lin Y, Hu Y, Son NH, Bharadwaj KG, Palacios C, Chokshi A, Ji R, Yu S, Homma S, Schulze PC, Tian R, Goldberg IJ. Rescue of heart lipoprotein lipase-knockout mice confirms a role for triglyceride in optimal heart metabolism and function. Am J Physiol Endocrinol Metab 2013; 305:E1339-47. [PMID: 24085031 PMCID: PMC3882371 DOI: 10.1152/ajpendo.00349.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hearts utilize fatty acids as a primary source of energy. The sources of those lipids include free fatty acids and lipoprotein triglycerides. Deletion of the primary triglyceride-hydrolyzing enzyme lipoprotein lipase (LPL) leads to cardiac dysfunction. Whether heart LPL-knockout (hLPL0) mice are compromised due a deficiency in energetic substrates is unknown. To test whether alternative sources of energy will prevent cardiac dysfunction in hLPL0 mice, two different models were used to supply nonlipid energy. 1) hLPL0 mice were crossed with mice transgenically expressing GLUT1 in cardiomyocytes to increase glucose uptake into the heart; this cross-corrected cardiac dysfunction, reduced cardiac hypertrophy, and increased myocardial ATP. 2) Mice were randomly assigned to a sedentary or training group (swimming) at 3 mo of age, which leads to increased skeletal muscle production of lactate. hLPL0 mice had greater expression of the lactate transporter monocarboxylate transporter-1 (MCT-1) and increased cardiac lactate uptake. Compared with hearts from sedentary hLPL0 mice, hearts from trained hLPL0 mice had adaptive hypertrophy and improved cardiac function. We conclude that defective energy intake and not the reduced uptake of fat-soluble vitamins or cholesterol is responsible for cardiac dysfunction in hLPL0 mice. In addition, our studies suggest that adaptations in cardiac metabolism contribute to the beneficial effects of exercise on the myocardium of patients with heart failure.
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Garcia-Arcos I, Hiyama Y, Drosatos K, Bharadwaj KG, Hu Y, Son NH, O'Byrne SM, Chang CL, Deckelbaum RJ, Takahashi M, Westerterp M, Obunike JC, Jiang H, Yagyu H, Blaner WS, Goldberg IJ. Adipose-specific lipoprotein lipase deficiency more profoundly affects brown than white fat biology. J Biol Chem 2013; 288:14046-14058. [PMID: 23542081 DOI: 10.1074/jbc.m113.469270] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adipose fat storage is thought to require uptake of circulating triglyceride (TG)-derived fatty acids via lipoprotein lipase (LpL). To determine how LpL affects the biology of adipose tissue, we created adipose-specific LpL knock-out (ATLO) mice, and we compared them with whole body LpL knock-out mice rescued with muscle LpL expression (MCK/L0) and wild type (WT) mice. ATLO LpL mRNA and activity were reduced, respectively, 75 and 70% in gonadal adipose tissue (GAT), 90 and 80% in subcutaneous tissue, and 84 and 85% in brown adipose tissue (BAT). ATLO mice had increased plasma TG levels associated with reduced chylomicron TG uptake into BAT and lung. ATLO BAT, but not GAT, had altered TG composition. GAT from MCK/L0 was smaller and contained less polyunsaturated fatty acids in TG, although GAT from ATLO was normal unless LpL was overexpressed in muscle. High fat diet feeding led to less adipose in MCK/L0 mice but TG acyl composition in subcutaneous tissue and BAT reverted to that of WT. Therefore, adipocyte LpL in BAT modulates plasma lipoprotein clearance, and the greater metabolic activity of this depot makes its lipid composition more dependent on LpL-mediated uptake. Loss of adipose LpL reduces fat accumulation only if accompanied by greater LpL activity in muscle. These data support the role of LpL as the "gatekeeper" for tissue lipid distribution.
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Affiliation(s)
- Itsaso Garcia-Arcos
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Yaeko Hiyama
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Konstantinos Drosatos
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Kalyani G Bharadwaj
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Yunying Hu
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Ni Huiping Son
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Sheila M O'Byrne
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Chuchun L Chang
- Institute of Human Nutrition, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Richard J Deckelbaum
- Institute of Human Nutrition, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Manabu Takahashi
- Department of Medicine, Jichii University, Tochigi 329-0498, Japan
| | - Marit Westerterp
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Medical Biochemistry, University of Amsterdam, 1105AZ Amsterdam, The Netherlands
| | - Joseph C Obunike
- Department of Biological Sciences, New York City College of Technology, City University of New York, Brooklyn, New York 11201
| | - Hongfeng Jiang
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Hiroaki Yagyu
- Department of Medicine, Jichii University, Tochigi 329-0498, Japan
| | - William S Blaner
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Ira J Goldberg
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032.
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Hu C, Ge F, Hyodo E, Arai K, Iwata S, Lobdell H, Walewski JL, Zhou S, Clugston RD, Jiang H, Zizola CP, Bharadwaj KG, Blaner WS, Homma S, Schulze PC, Goldberg IJ, Berk PD. Chronic ethanol consumption increases cardiomyocyte fatty acid uptake and decreases ventricular contractile function in C57BL/6J mice. J Mol Cell Cardiol 2013; 59:30-40. [PMID: 23422163 DOI: 10.1016/j.yjmcc.2013.02.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 02/01/2013] [Accepted: 02/02/2013] [Indexed: 02/07/2023]
Abstract
Alcohol, a major cause of human cardiomyopathy, decreases cardiac contractility in both animals and man. However, key features of alcohol-related human heart disease are not consistently reproduced in animal models. Accordingly, we studied cardiac histology, contractile function, cardiomyocyte long chain fatty acid (LCFA) uptake, and gene expression in male C57BL/6J mice consuming 0, 10, 14, or 18% ethanol in drinking water for 3months. At sacrifice, all EtOH groups had mildly decreased body and increased heart weights, dose-dependent increases in cardiac triglycerides and a marked increase in cardiac fatty acid ethyl esters. [(3)H]-oleic acid uptake kinetics demonstrated increased facilitated cardiomyocyte LCFA uptake, associated with increased expression of genes encoding the LCFA transporters CD36 and Slc27a1 (FATP1) in EtOH-fed animals. Although SCD-1 expression was increased, lipidomic analysis did not indicate significantly increased de novo LCFA synthesis. By echocardiography, ejection fraction (EF) and the related fractional shortening (FS) of left ventricular diameter during systole were reduced and negatively correlated with cardiac triglycerides. Expression of myocardial PGC-1α and multiple downstream target genes in the oxidative phosphorylation pathway, including several in the electron transport and ATP synthase complexes of the inner mitochondrial membrane, were down-regulated. Cardiac ATP was correspondingly reduced. The data suggest that decreased expression of PGC-1α and its target genes result in decreased cardiac ATP levels, which may explain the decrease in myocardial contractile function caused by chronic EtOH intake. This model recapitulates important features of human alcoholic cardiomyopathy and illustrates a potentially important pathophysiologic link between cardiac lipid metabolism and function.
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Affiliation(s)
- Chunguang Hu
- The Department of Medicine, Division of Digestive & Liver Disease, Columbia University College of Physicians & Surgeons, New York, NY 10032, USA
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Putnam K, Batifoulier-Yiannikouris F, Bharadwaj KG, Lewis E, Karounos M, Daugherty A, Cassis LA. Deficiency of angiotensin type 1a receptors in adipocytes reduces differentiation and promotes hypertrophy of adipocytes in lean mice. Endocrinology 2012; 153:4677-86. [PMID: 22919058 PMCID: PMC3512029 DOI: 10.1210/en.2012-1352] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Adipocytes express angiotensin receptors, but the direct effects of angiotensin II (AngII) stimulating this cell type are undefined. Adipocytes express angiotensin type 1a receptor (AT1aR) and AT2R, both of which have been implicated in obesity. In this study, we determined the effects of adipocyte AT1aR deficiency on adipocyte differentiation and the development of obesity in mice fed low-fat (LF) or high-fat (HF) diets. Mice expressing Cre recombinase under the control of the aP2 promoter were bred with AT1aR-floxed mice to generate mice with adipocyte AT1aR deficiency (AT1aR(aP2)). AT1aR mRNA abundance was reduced significantly in both white and brown adipose tissue from AT1aR(aP2) mice compared with nontransgenic littermates (AT1aR(fl/fl)). Adipocyte AT1aR deficiency did not influence body weight, glucose tolerance, or blood pressure in mice fed either LF or high-fat diets. However, LF-fed AT1aR(aP2) mice exhibited striking adipocyte hypertrophy even though total fat mass was not different between genotypes. Stromal vascular cells from AT1aR(aP2) mice differentiated to a lesser extent to adipocytes compared with controls. Conversely, incubation of 3T3-L1 adipocytes with AngII increased Oil Red O staining and increased mRNA abundance of peroxisome proliferator-activated receptor γ (PPARγ) via AT1R stimulation. These results suggest that reductions in adipocyte differentiation in LF-fed AT1aR(aP2) mice resulted in increased lipid storage and hypertrophy of remaining adipocytes. These results demonstrate that AngII regulates adipocyte differentiation and morphology through the adipocyte AT1aR in lean mice.
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Affiliation(s)
- Kelly Putnam
- Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, Kentucky 40536-0200, USA
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Lee SY, Kim JR, Hu Y, Khan R, Kim SJ, Bharadwaj KG, Davidson MM, Choi CS, Shin KO, Lee YM, Park WJ, Park IS, Jiang XC, Goldberg IJ, Park TS. Cardiomyocyte specific deficiency of serine palmitoyltransferase subunit 2 reduces ceramide but leads to cardiac dysfunction. J Biol Chem 2012; 287:18429-39. [PMID: 22493506 DOI: 10.1074/jbc.m111.296947] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The role of serine palmitoyltransferase (SPT) and de novo ceramide biosynthesis in cardiac ceramide and sphingomyelin metabolism is unclear. To determine whether the de novo synthetic pathways, rather than ceramide uptake from circulating lipoproteins, is important for heart ceramide levels, we created cardiomyocyte-specific deficiency of Sptlc2, a subunit of SPT. Heart-specific Sptlc2-deficient (hSptlc2 KO) mice had a >35% reduction in ceramide, which was limited to C18:0 and very long chain ceramides. Sphingomyelinase expression, and levels of sphingomyelin and diacylglycerol were unchanged. But surprisingly phospholipids and acyl CoAs contained increased saturated long chain fatty acids. hSptlc2 KO mice had decreased fractional shortening and thinning of the cardiac wall. While the genes regulating glucose and fatty acid metabolism were not changed, expression of cardiac failure markers and the genes involved in the formation of extracellular matrices were up-regulated in hSptlc2 KO hearts. In addition, ER-stress markers were up-regulated leading to increased apoptosis. These results suggest that Sptlc2-mediated de novo ceramide synthesis is an essential source of C18:0 and very long chain, but not of shorter chain, ceramides in the heart. Changes in heart lipids other than ceramide levels lead to cardiac toxicity.
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Affiliation(s)
- Su-Yeon Lee
- Department of Life Science, Gachon University, Seongnam-Si, Gyeonggi-Do, Republic of Korea
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Lee HY, Birkenfeld AL, Jornayvaz FR, Jurczak MJ, Kanda S, Popov V, Frederick DW, Zhang D, Guigni B, Bharadwaj KG, Choi CS, Goldberg IJ, Park JH, Petersen KF, Samuel VT, Shulman GI. Apolipoprotein CIII overexpressing mice are predisposed to diet-induced hepatic steatosis and hepatic insulin resistance. Hepatology 2011; 54:1650-60. [PMID: 21793029 PMCID: PMC3205235 DOI: 10.1002/hep.24571] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 07/12/2011] [Indexed: 12/11/2022]
Abstract
UNLABELLED Nonalcoholic fatty liver disease (NAFLD) and insulin resistance have recently been found to be associated with increased plasma concentrations of apolipoprotein CIII (APOC3) in humans carrying single nucleotide polymorphisms within the insulin response element of the APOC3 gene. To examine whether increased expression of APOC3 would predispose mice to NAFLD and hepatic insulin resistance, human APOC3 overexpressing (ApoC3Tg) mice were metabolically phenotyped following either a regular chow or high-fat diet (HFD). After HFD feeding, ApoC3Tg mice had increased hepatic triglyceride accumulation, which was associated with cellular ballooning and inflammatory changes. ApoC3Tg mice also manifested severe hepatic insulin resistance assessed by a hyperinsulinemic-euglycemic clamp, which could mostly be attributed to increased hepatic diacylglycerol content, protein kinase C-ϵ activation, and decreased insulin-stimulated Akt2 activity. Increased hepatic triglyceride content in the HFD-fed ApoC3Tg mice could be attributed to a ≈ 70% increase in hepatic triglyceride uptake and ≈ 50% reduction hepatic triglyceride secretion. CONCLUSION These data demonstrate that increase plasma APOC3 concentrations predispose mice to diet-induced NAFLD and hepatic insulin resistance.
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Affiliation(s)
- Hui-Young Lee
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT,Department of Cellular & Molecular Physiology, Yale University School of MedicineNew Haven, CT,Howard Hughes Medical Institute, Yale University School of MedicineNew Haven, CT
| | - Andreas L Birkenfeld
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT
| | - Francois R Jornayvaz
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT
| | - Michael J Jurczak
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT,Howard Hughes Medical Institute, Yale University School of MedicineNew Haven, CT
| | - Shoichi Kanda
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT
| | - Violeta Popov
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT
| | - David W Frederick
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT
| | - Dongyan Zhang
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT,Howard Hughes Medical Institute, Yale University School of MedicineNew Haven, CT
| | - Blas Guigni
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT
| | | | - Cheol Soo Choi
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT
| | | | - Jae-Hak Park
- Department of Laboratory Animal Medicine, College of Veterinary Medicine, Seoul National UniversitySeoul, Korea
| | - Kitt F Petersen
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT,Department of Cellular & Molecular Physiology, Yale University School of MedicineNew Haven, CT
| | - Varman T Samuel
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT,Department of Cellular & Molecular Physiology, Yale University School of MedicineNew Haven, CT
| | - Gerald I Shulman
- Department of Internal Medicine, Yale University School of MedicineNew Haven, CT,Department of Cellular & Molecular Physiology, Yale University School of MedicineNew Haven, CT,Howard Hughes Medical Institute, Yale University School of MedicineNew Haven, CT
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Drosatos K, Bharadwaj KG, Lymperopoulos A, Ikeda S, Khan R, Hu Y, Agarwal R, Yu S, Jiang H, Steinberg SF, Blaner WS, Koch WJ, Goldberg IJ. Cardiomyocyte lipids impair β-adrenergic receptor function via PKC activation. Am J Physiol Endocrinol Metab 2011; 300:E489-99. [PMID: 21139071 PMCID: PMC3064003 DOI: 10.1152/ajpendo.00569.2010] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Normal hearts have increased contractility in response to catecholamines. Because several lipids activate PKCs, we hypothesized that excess cellular lipids would inhibit cardiomyocyte responsiveness to adrenergic stimuli. Cardiomyocytes treated with saturated free fatty acids, ceramide, and diacylglycerol had reduced cellular cAMP response to isoproterenol. This was associated with increased PKC activation and reduction of β-adrenergic receptor (β-AR) density. Pharmacological and genetic PKC inhibition prevented both palmitate-induced β-AR insensitivity and the accompanying reduction in cell surface β-ARs. Mice with excess lipid uptake due to either cardiac-specific overexpression of anchored lipoprotein lipase, PPARγ, or acyl-CoA synthetase-1 or high-fat diet showed reduced inotropic responsiveness to dobutamine. This was associated with activation of protein kinase C (PKC)α or PKCδ. Thus, several lipids that are increased in the setting of lipotoxicity can produce abnormalities in β-AR responsiveness. This can be attributed to PKC activation and reduced β-AR levels.
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Affiliation(s)
- Konstantinos Drosatos
- Dept. of Medicine, Columbia University, 630 West 168th St., New York, NY 10032, USA.
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Wang H, Astarita G, Taussig MD, Bharadwaj KG, DiPatrizio NV, Nave KA, Piomelli D, Goldberg IJ, Eckel RH. Deficiency of lipoprotein lipase in neurons modifies the regulation of energy balance and leads to obesity. Cell Metab 2011; 13:105-13. [PMID: 21195353 PMCID: PMC3034302 DOI: 10.1016/j.cmet.2010.12.006] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 08/24/2010] [Accepted: 11/04/2010] [Indexed: 01/30/2023]
Abstract
Free fatty acids (FFAs) suppress appetite when injected into the hypothalamus. To examine whether lipoprotein lipase (LPL), a serine hydrolase that releases FFAs from circulating triglyceride (TG)-rich lipoproteins, might contribute to FFA-mediated signaling in the brain, we created neuron-specific LPL-deficient mice. Homozygous mutant (NEXLPL-/-) mice were hyperphagic and became obese by 16 weeks of age. These traits were accompanied by elevations in the hypothalamic orexigenic neuropeptides, AgRP and NPY, and were followed by reductions in metabolic rate. The uptake of TG-rich lipoprotein fatty acids was reduced in the hypothalamus of 3-month-old NEXLPL-/- mice. Moreover, deficiencies in essential fatty acids in the hypothalamus were evident by 3 months, with major deficiencies of long-chain n-3 fatty acids by 12 months. These results indicate that TG-rich lipoproteins are sensed in the brain by an LPL-dependent mechanism and provide lipid signals for the central regulation of body weight and energy balance.
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Affiliation(s)
- Hong Wang
- Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, University of Colorado, Denver Anschutz Medical Campus, Aurora, CO 80045, USA
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Liu L, Yu S, Khan RS, Ables GP, Bharadwaj KG, Hu Y, Huggins LA, Eriksson JW, Buckett LK, Turnbull AV, Ginsberg HN, Blaner WS, Huang LS, Goldberg IJ. DGAT1 deficiency decreases PPAR expression and does not lead to lipotoxicity in cardiac and skeletal muscle. J Lipid Res 2011; 52:732-44. [PMID: 21205704 DOI: 10.1194/jlr.m011395] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Diacylglycerol (DAG) acyl transferase 1 (Dgat1) knockout ((-/-)) mice are resistant to high-fat-induced obesity and insulin resistance, but the reasons are unclear. Dgat1(-/-) mice had reduced mRNA levels of all three Ppar genes and genes involved in fatty acid oxidation in the myocardium of Dgat1(-/-) mice. Although DGAT1 converts DAG to triglyceride (TG), tissue levels of DAG were not increased in Dgat1(-/-) mice. Hearts of chow-diet Dgat1(-/-) mice were larger than those of wild-type (WT) mice, but cardiac function was normal. Skeletal muscles from Dgat1(-/-) mice were also larger. Muscle hypertrophy factors phospho-AKT and phospho-mTOR were increased in Dgat1(-/-) cardiac and skeletal muscle. In contrast to muscle, liver from Dgat1(-/-) mice had no reduction in mRNA levels of genes mediating fatty acid oxidation. Glucose uptake was increased in cardiac and skeletal muscle in Dgat1(-/-) mice. Treatment with an inhibitor specific for DGAT1 led to similarly striking reductions in mRNA levels of genes mediating fatty acid oxidation in cardiac and skeletal muscle. These changes were reproduced in cultured myocytes with the DGAT1 inhibitor, which also blocked the increase in mRNA levels of Ppar genes and their targets induced by palmitic acid. Thus, loss of DGAT1 activity in muscles decreases mRNA levels of genes involved in lipid uptake and oxidation.
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Affiliation(s)
- Li Liu
- Division of Preventive Medicine and Nutrition, Columbia University, New York, NY, USA
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Bharadwaj KG, Hiyama Y, Hu Y, Huggins LA, Ramakrishnan R, Abumrad NA, Shulman GI, Blaner WS, Goldberg IJ. Chylomicron- and VLDL-derived lipids enter the heart through different pathways: in vivo evidence for receptor- and non-receptor-mediated fatty acid uptake. J Biol Chem 2010; 285:37976-86. [PMID: 20852327 DOI: 10.1074/jbc.m110.174458] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Lipids circulate in the blood in association with plasma lipoproteins and enter the tissues either after hydrolysis or as non-hydrolyzable lipid esters. We studied cardiac lipids, lipoprotein lipid uptake, and gene expression in heart-specific lipoprotein lipase (LpL) knock-out (hLpL0), CD36 knock-out (Cd36(-/-)), and double knock-out (hLpL0/Cd36(-/-)-DKO) mice. Loss of either LpL or CD36 led to a significant reduction in heart total fatty acyl-CoA (control, 99.5 ± 3.8; hLpL0, 36.2 ± 3.5; Cd36(-/-), 57.7 ± 5.5 nmol/g, p < 0.05) and an additive effect was observed in the DKO (20.2 ± 1.4 nmol/g, p < 0.05). Myocardial VLDL-triglyceride (TG) uptake was reduced in the hLpL0 (31 ± 6%) and Cd36(-/-) (47 ± 4%) mice with an additive reduction in the DKO (64 ± 5%) compared with control. However, LpL but not CD36 deficiency decreased VLDL-cholesteryl ester uptake. Endogenously labeled mouse chylomicrons were produced by tamoxifen treatment of β-actin-MerCreMer/LpL(flox/flox) mice. Induced loss of LpL increased TG levels >10-fold and reduced HDL by >50%. After injection of these labeled chylomicrons in the different mice, chylomicron TG uptake was reduced by ∼70% and retinyl ester by ∼50% in hLpL0 hearts. Loss of CD36 did not alter either chylomicron TG or retinyl ester uptake. LpL loss did not affect uptake of remnant lipoproteins from ApoE knock-out mice. Our data are consistent with two pathways for fatty acid uptake; a CD36 process for VLDL-derived fatty acid and a non-CD36 process for chylomicron-derived fatty acid uptake. In addition, our data show that lipolysis is involved in uptake of core lipids from TG-rich lipoproteins.
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Affiliation(s)
- Kalyani G Bharadwaj
- Division of Preventive Medicine and Nutrition, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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Duncan JG, Bharadwaj KG, Fong JL, Mitra R, Sambandam N, Courtois MR, Lavine KJ, Goldberg IJ, Kelly DP. Rescue of cardiomyopathy in peroxisome proliferator-activated receptor-alpha transgenic mice by deletion of lipoprotein lipase identifies sources of cardiac lipids and peroxisome proliferator-activated receptor-alpha activators. Circulation 2010; 121:426-35. [PMID: 20065164 DOI: 10.1161/circulationaha.109.888735] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Emerging evidence in obesity and diabetes mellitus demonstrates that excessive myocardial fatty acid uptake and oxidation contribute to cardiac dysfunction. Transgenic mice with cardiac-specific overexpression of the fatty acid-activated nuclear receptor peroxisome proliferator-activated receptor-alpha (myosin heavy chain [MHC]-PPARalpha mice) exhibit phenotypic features of the diabetic heart, which are rescued by deletion of CD36, a fatty acid transporter, despite persistent activation of PPARalpha gene targets involved in fatty acid oxidation. METHODS AND RESULTS To further define the source of fatty acid that leads to cardiomyopathy associated with lipid excess, we crossed MHC-PPARalpha mice with mice deficient for cardiac lipoprotein lipase (hsLpLko). MHC-PPARalpha/hsLpLko mice exhibit improved cardiac function and reduced myocardial triglyceride content compared with MHC-PPARalpha mice. Surprisingly, in contrast to MHC-PPARalpha/CD36ko mice, the activity of the cardiac PPARalpha gene regulatory pathway is normalized in MHC-PPARalpha/hsLpLko mice, suggesting that PPARalpha ligand activity exists in the lipoprotein particle. Indeed, LpL mediated hydrolysis of very-low-density lipoprotein activated PPARalpha in cardiac myocytes in culture. The rescue of cardiac function in both models was associated with improved mitochondrial ultrastructure and reactivation of transcriptional regulators of mitochondrial function. CONCLUSIONS MHC-PPARalpha mouse hearts acquire excess lipoprotein-derived lipids. LpL deficiency rescues myocyte triglyceride accumulation, mitochondrial gene regulatory derangements, and contractile function in MHC-PPARalpha mice. Finally, LpL serves as a source of activating ligand for PPARalpha in the cardiomyocyte.
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Affiliation(s)
- Jennifer G Duncan
- Center for Cardiovascular Research, Washington University School of Medicine, St Louis, Mo., USA
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Liu L, Shi X, Bharadwaj KG, Ikeda S, Yamashita H, Yagyu H, Schaffer JE, Yu YH, Goldberg IJ. DGAT1 expression increases heart triglyceride content but ameliorates lipotoxicity. J Biol Chem 2009; 284:36312-36323. [PMID: 19778901 DOI: 10.1074/jbc.m109.049817] [Citation(s) in RCA: 186] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Intracellular lipid accumulation in the heart is associated with cardiomyopathy, yet the precise role of triglyceride (TG) remains unclear. With exercise, wild type hearts develop physiologic hypertrophy. This was associated with greater TG stores and a marked induction of the TG-synthesizing enzyme diacylglycerol (DAG) acyltransferase 1 (DGAT1). Transgenic overexpression of DGAT1 in the heart using the cardiomyocyte- specific alpha-myosin heavy chain (MHC) promoter led to approximately a doubling of DGAT activity and TG content and reductions of approximately 35% in cardiac ceramide, 26% in DAG, and 20% in free fatty acid levels. Cardiac function assessed by echocardiography and cardiac catheterization was unaffected. These mice were then crossed with animals expressing long-chain acyl-CoA synthetase via the MHC promoter (MHC-ACS), which develop lipotoxic cardiomyopathy. MHC-DGAT1XMHC-ACS double transgenic male mice had improved heart function; fractional shortening increased by 74%, and diastolic function improved compared with MHC-ACS mice. The improvement of heart function correlated with a reduction in cardiac DAG and ceramide and reduced cardiomyocyte apoptosis but increased fatty acid oxidation. In addition, the survival of the mice was improved. Our study indicates that TG is not likely to be a toxic lipid species directly, but rather it is a feature of physiologic hypertrophy and may serve a cytoprotective role in lipid overload states. Moreover, induction of DGAT1 could be beneficial in the setting of excess heart accumulation of toxic lipids.
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Affiliation(s)
- Li Liu
- Department of Medicine, Division of Preventive Medicine and Metabolism, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - XiaoJing Shi
- Department of Medicine, Division of Preventive Medicine and Metabolism, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Kalyani G Bharadwaj
- Department of Medicine, Division of Preventive Medicine and Metabolism, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Shota Ikeda
- Department of Medicine, Division of Preventive Medicine and Metabolism, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Haruyo Yamashita
- Department of Medicine, Division of Preventive Medicine and Metabolism, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Hiroaki Yagyu
- Department of Medicine, Division of Preventive Medicine and Metabolism, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Jean E Schaffer
- Division of Cardiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Yi-Hao Yu
- Department of Medicine, Division of Preventive Medicine and Metabolism, Columbia University College of Physicians and Surgeons, New York, New York 10032
| | - Ira J Goldberg
- Department of Medicine, Division of Preventive Medicine and Metabolism, Columbia University College of Physicians and Surgeons, New York, New York 10032.
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Abstract
Fatty acids (FAs) are acquired from free FA associated with albumin and lipoprotein triglyceride that is hydrolyzed by lipoprotein lipase (LpL). Hypertrophied hearts shift their substrate usage pattern to more glucose and less FA. However, FAs may still be an important source of energy in hypertrophied hearts. The aim of this study was to examine the importance of LpL-derived FAs in hypertensive hypertrophied hearts. We followed cardiac function and metabolic changes during 2 wk of angiotensin II (ANG II)-induced hypertension in control and heart-specific lipoprotein lipase knockout (hLpL0) mice. Glucose metabolism was increased in ANG II-treated control (control/ANG II) hearts, raising it to the same level as hLpL0 hearts. FA uptake-related genes, CD36 and FATP1, were reduced in control/ANG II hearts to levels found in hLpL0 hearts. ANG II did not alter these metabolic genes in hLpL0 mice. LpL activity was preserved, and mitochondrial FA oxidation-related genes were not altered in control/ANG II hearts. In control/ANG II hearts, triglyceride stores were consumed and reached the same levels as in hLpL0/ANG II hearts. Intracellular ATP content was reduced only in hLpL0/ANG II hearts. Both ANG II and deoxycorticosterone acetate-salt induced hypertension caused heart failure only in hLpL0 mice. Our data suggest that LpL activity is required for normal cardiac metabolic compensation to hypertensive stress.
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Bharadwaj KG, Bruemmer DC, Cassis LA. Angiotensin II upregulates PPARgamma gene and transcriptional activity during 3T3‐L1 adipocyte differentiation via the AT1 receptor subtype. FASEB J 2006. [DOI: 10.1096/fasebj.20.5.lb107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kalyani G Bharadwaj
- Pharmaceutical SciencesUniversity of Kentucky725 Rose streetlexingtonKentucky40536
| | | | - Lisa Ann Cassis
- Graduate Center for Nutritional SciencesUniversity of Kentucky900 S limestoneLexingtonKentucky40536
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