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Abstract
Peroxisome proliferator-activated receptors (PPARs) are nuclear receptor-type transcription factors with three subtypes (α, δ, and γ) that regulate cell differentiation and metabolism. Co-crystals of human PPARα-ligand-binding domain (LBD)-PPARα ligand for X-ray crystallography have been difficult to obtain. Recombinant human PPARα-LBD proteins contain intrinsic fatty acids (iFAs of Escherichia coli origin) and may be unstable without ligands during crystallization. To circumvent these limitations, we have successfully applied various crystallization techniques, including co-crystallization, cross-seeding, soaking, delipidation, and coactivator peptide supplementation. For complete details on the use and execution of this protocol, please refer to Kamata et al. (2020). Protocols for recombinant PPARα ligand-binding domain protein purification Techniques to prepare PPARα-ligand co-crystals for high-resolution X-ray crystallography Strategy to obtain PPARα co-crystals with low-affinity PPARα ligands
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Affiliation(s)
- Shotaro Kamata
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Takuji Oyama
- Faculty of Life and Environmental Sciences, University of Yamanashi, Kofu, Yamanashi 400-8510, Japan
| | - Isao Ishii
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
- Corresponding author
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Hwang SB, Lee BH. Anti-Obesity and Antidiabetic Effects of Nelumbinis Semen Powder in High-Fat Diet-Induced Obese C57BL/6 Mice. Nutrients 2020; 12:nu12113576. [PMID: 33266423 PMCID: PMC7700195 DOI: 10.3390/nu12113576] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 01/09/2023] Open
Abstract
Nelumbinis Semen (NS, the seeds of Nelumbo nucifera) extract is a traditional Korean medicine with anti-oxidant activity. The present study examined the anti-obesity and antidiabetic effects of NS powder in high-fat diet (HFD)-induced obese C57BL/6 mice. Mice (n = 8/group) were fed a normal diet (CON), HFD, HFD containing 5% NS powder (HFD-NS5%), or HFD containing 10% NS powder (HFD-NS10%) for 12 weeks. Food intake was relatively higher in groups HFD-NS5% and HFD-NS10%, while the food efficiency ratio was highest in group HFD (p < 0.05). HFD-NS5% reduced the body weight (-39.1%) and fat weight (-26.6%), including epididymal fat and perirenal fat, and lowered the serum triglyceride levels (-20.6%) compared with HFD. Groups HFD-NS5% and HFD-NS10% showed hepatoprotective properties, reducing the serum ALT levels (p < 0.05) and fat globules (size and number) in the liver compared with group HFD. HFD-NS5% and HFD-NS10% regulated the blood glucose, improved the glucose intolerance, and showed a 12.5% and 15.0% reduction in the area under the curve (AUC) of intraperitoneal glucose tolerance test (IPGTT), and a 26.8% and 47.3% improvement in homeostatic model assessment insulin resistance (HOMA-IR), respectively, compared with HFD (p < 0.05). Regarding the expressions of genes related to anti-obesity and antidiabetes, there was a 1.7- and 1.3-fold increase in PPAR-α protein expression, 1.4- and 1.6-fold increase in PPAR-γ protein expression, and 0.7- and 0.6-fold decrease in TNF-α protein expression, respectively, following HFD-NS5% and HFD-NS10% treatments, compared with HFD, and GLUT4 protein expression increased relative to CON (p < 0.05). These results comprehensively provide the fundamental data for NS powder's functional and health-promoting benefits associated with anti-obesity and antidiabetes.
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Nardelli C, Iaffaldano L, Pilone V, Labruna G, Ferrigno M, Carlomagno N, Dodaro CA, Forestieri P, Buono P, Salvatore F, Sacchetti L. Changes in the MicroRNA Profile Observed in the Subcutaneous Adipose Tissue of Obese Patients after Laparoscopic Adjustable Gastric Banding. J Obes 2017; 2017:6754734. [PMID: 28386478 PMCID: PMC5366784 DOI: 10.1155/2017/6754734] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 02/17/2017] [Accepted: 02/23/2017] [Indexed: 12/29/2022] Open
Abstract
Background. Laparoscopic adjustable gastric banding (LAGB) results in significant lasting weight loss and improved metabolism in obese patients. To evaluate whether epigenetic factors could concur to these benefits, we investigated the subcutaneous adipose tissue (SAT) microRNA (miRNA) profile before (T0) and three years (T1) after LAGB in three morbidly obese women. Case Reports. SAT miRNA profiling, evaluated by TaqMan Array, showed four downexpressed (miR-519d, miR-299-5p, miR-212, and miR-671-3p) and two upexpressed (miR-370 and miR-487a) miRNAs at T1 versus T0. Bioinformatics predicted that these miRNAs regulate genes belonging to pathways associated with the cytoskeleton, inflammation, and metabolism. Western blot analysis showed that PPAR-alpha, which is the target gene of miR-519d, increased after LAGB, thereby suggesting an improvement in SAT lipid metabolism. Accordingly, the number and diameter of adipocytes were significantly higher and lower, respectively, at T1 versus T0. Bioinformatics predicted that the decreased levels of miR-212, miR-299-5p, and miR-671-3p at T1 concur in reducing SAT inflammation. Conclusion. We show that the miRNA profile changes after LAGB. This finding, although obtained in only three cases, suggests that this epigenetic mechanism, by regulating the expression of genes involved in inflammation and lipid metabolism, could concur to improve SAT functionality in postoperative obese patients.
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Affiliation(s)
- Carmela Nardelli
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Via S. Pansini 5, 80131 Naples, Italy
- CEINGE-Biotecnologie Avanzate Scarl, Via G. Salvatore 486, 80145 Naples, Italy
| | - Laura Iaffaldano
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Via S. Pansini 5, 80131 Naples, Italy
- CEINGE-Biotecnologie Avanzate Scarl, Via G. Salvatore 486, 80145 Naples, Italy
| | - Vincenzo Pilone
- Dipartimento di Medicina e Chirurgia, Università di Salerno, Via Giovanni Paolo II 132, Fisciano, 84084 Salerno, Italy
| | - Giuseppe Labruna
- IRCCS SDN-Istituto di Ricerca Diagnostica e Nucleare, Via Gianturco 113, 80100 Naples, Italy
| | - Maddalena Ferrigno
- CEINGE-Biotecnologie Avanzate Scarl, Via G. Salvatore 486, 80145 Naples, Italy
| | - Nicola Carlomagno
- Dipartimento di Scienze Biomediche Avanzate, Università di Napoli Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Concetta Anna Dodaro
- Dipartimento di Scienze Biomediche Avanzate, Università di Napoli Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Pietro Forestieri
- Dipartimento di Medicina Clinica e Chirurgia, Università di Napoli Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Pasqualina Buono
- IRCCS SDN-Istituto di Ricerca Diagnostica e Nucleare, Via Gianturco 113, 80100 Naples, Italy
- Dipartimento Scienze Motorie e del Benessere, Università di Napoli Parthenope, Via Amm. F. Acton 38, 80133 Naples, Italy
| | - Francesco Salvatore
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Via S. Pansini 5, 80131 Naples, Italy
- CEINGE-Biotecnologie Avanzate Scarl, Via G. Salvatore 486, 80145 Naples, Italy
| | - Lucia Sacchetti
- CEINGE-Biotecnologie Avanzate Scarl, Via G. Salvatore 486, 80145 Naples, Italy
- *Lucia Sacchetti:
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Santos MHH, de Lourdes Higuchi M, Tucci PJF, Garavelo SM, Reis MM, Antonio EL, Serra AJ, Maranhão RC. Previous exercise training increases levels of PPAR-α in long-term post-myocardial infarction in rats, which is correlated with better inflammatory response. Clinics (Sao Paulo) 2016; 71:163-8. [PMID: 27074178 PMCID: PMC4785847 DOI: 10.6061/clinics/2016(03)08] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/21/2016] [Indexed: 01/09/2023] Open
Abstract
OBJECTIVE Exercise is a protective factor for cardiovascular morbidity and mortality, with unclear mechanisms. Changing the myocardial metabolism causes harmful consequences for heart function and exercise contributes to metabolic adjustment modulation. Peroxisome proliferator-activated receptors (PPARs) are also myocardium metabolism regulators capable of decreasing the inflammatory response. We hypothesized that PPAR-α is involved in the beneficial effects of previous exercise on myocardial infarction (MI) and cardiac function, changing the expression of metabolic and inflammatory response regulators and reducing myocardial apoptosis, which partially explains the better outcome. METHODS AND RESULTS Exercised rats engaged in swimming sessions for 60 min/day, 5 days/week, for 8 weeks. Both the exercised rats and sedentary rats were randomized to MI surgery and followed for 1 week (EI1 or SI1) or 4 weeks (EI4 or SI4) of healing or to sham groups. Echocardiography was employed to detect left ventricular function and the infarct size. Additionally, the TUNEL technique was used to assess apoptosis and immunohistochemistry was used to quantitatively analyze the PPAR-α, TNF-α and NF-κB antigens in the infarcted and non-infarcted myocardium. MI-related mortality was higher in SI4 than in EI4 (25% vs 12%), without a difference in MI size. SI4 exhibited a lower shortening fraction than EI4 did (24% vs 35%) and a higher apoptosis/area rate (3.97±0.61 vs 1.90±1.82) in infarcted areas (both p=0.001). Immunohistochemistry also revealed higher TNF-α levels in SI1 than in EI1 (9.59 vs 4.09, p<0.001) in infarcted areas. In non-infarcted areas, EI4 showed higher levels of TNF-α and positive correlations between PPAR-α and NF-κB (r=0.75, p=0.02), in contrast to SI4 (r=0.05, p=0.87). CONCLUSION Previously exercised animals had better long-term ventricular function post-MI, in addition to lower levels of local inflammatory markers and less myocardial apoptosis, which seemed to be related to the presence of PPAR-α.
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Affiliation(s)
- Marília Harumi Higuchi Santos
- Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Instituto do Coração (InCor), Laboratório de Patologia Cardíaca, São Paulo/, SP, Brazil
- E-mail:
| | - Maria de Lourdes Higuchi
- Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Instituto do Coração (InCor), Laboratório de Patologia Cardíaca, São Paulo/, SP, Brazil
| | | | - Shérrira M Garavelo
- Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Instituto do Coração (InCor), Laboratório de Patologia Cardíaca, São Paulo/, SP, Brazil
| | - Márcia M Reis
- Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Instituto do Coração (InCor), Laboratório de Patologia Cardíaca, São Paulo/, SP, Brazil
| | | | | | - Raul Cavalcante Maranhão
- Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Instituto do Coração (InCor), Laboratório de Patologia Cardíaca, São Paulo/, SP, Brazil
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Shores NJ, Mendes-Corrêa MC, Maida I, Turner J, High KP, Babudieri S, Núñez M. Hepatic peroxisome proliferator-activated receptor γ and α-mRNA expression in HCV-infected adults is decreased by HIV co-infection and is also affected by ethnicity. Clinics (Sao Paulo) 2015; 70:790-6. [PMID: 26735218 PMCID: PMC4676314 DOI: 10.6061/clinics/2015(12)05] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Accepted: 10/20/2015] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVE To determine peroxisome proliferator activated receptor α and γ mRNA expression in liver tissue of hepatitis C virus-infected patients with and without human immunodeficiency virus and its possible contribution to an acceleration of liver disease progression. METHODS We measured peroxisome proliferator-activated receptor α and γ mRNA expression by real-time polymerase chain reaction in liver tissues from 40 subjects infected only with hepatitis C virus, 36 subjects co-infected with hepatitis C virus and human immunodeficiency virus and 11 normal adults. RESULTS Hepatic mRNA expression of both peroxisome proliferator-activated receptors was significantly lower in hepatitis C virus-infected subjects with and without human immunodeficiency virus co-infection compared to the controls. Non-black race was also identified as a predictor of lower peroxisome receptor α and γ mRNA expression. Compared to subjects infected only with hepatitis C virus, liver peroxisome receptor γ mRNA expression was significantly lower in hepatitis C virus/human immunodeficiency virus-co-infected subjects (0.0092 in hepatitis C virus/human immunodeficiency virus-co-infection vs. 0.0120 in hepatitis C virus-only; p=0.004). Hepatic peroxisome receptor α mRNA expression in the hepatitis C virus-infected patients was lower in the presence of human immunodeficiency virus co-infection in non-black subjects (0.0769 vs. 0.1061; p=0.02), whereas the levels did not vary based on human immunodeficiency virus status among black subjects. CONCLUSION mRNA expression of both peroxisome proliferator-activated receptors is impaired in hepatitis C virus-infected liver and further reduced by human immunodeficiency virus co-infection, although the suppressive effects of the viruses are substantially mitigated in black patients.
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Affiliation(s)
- Nathan J Shores
- Wake Forest University Health Sciences, Department of Internal Medicine, Section on Infectious Diseases, Medical Center Boulevard, Winston Salem, NC, United States
- Charleston Gastroenterology Spec, Charleston/SC, United States
| | - Maria Cássia Mendes-Corrêa
- Faculdade de Medicina do ABC, Unidade de Referência em Doenças Infecciosas, Santo André/SP, Brazil
- Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Moléstias Infecciosas e Parasitárias, São Paulo/SP, Brazil
- Corresponding author: E-mail:
| | - Ivana Maida
- Università degli Studi Sassari, Istituto Malattie Infettive e Parassitarie, Sassari/SS, Italy
| | - JoLyn Turner
- Wake Forest University Health Sciences, Department of Internal Medicine, Section on Infectious Diseases, Medical Center Boulevard, Winston Salem, NC, United States
| | - Kevin P High
- Wake Forest University Health Sciences, Department of Internal Medicine, Section on Infectious Diseases, Medical Center Boulevard, Winston Salem, NC, United States
| | - Sergio Babudieri
- Università degli Studi Sassari, Istituto Malattie Infettive e Parassitarie, Sassari/SS, Italy
| | - Marina Núñez
- Wake Forest University Health Sciences, Department of Internal Medicine, Section on Infectious Diseases, Medical Center Boulevard, Winston Salem, NC, United States
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Li G, Wang J, Ye J, Zhang Y, Zhang Y. PPARα Protein Expression Was Increased by Four Weeks of Intermittent Hypoxic Training via AMPKα2-Dependent Manner in Mouse Skeletal Muscle. PLoS One 2015; 10:e0122593. [PMID: 25923694 PMCID: PMC4414596 DOI: 10.1371/journal.pone.0122593] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 02/11/2015] [Indexed: 01/01/2023] Open
Abstract
Peroxisome proliferator-activated receptor α (PPARα) is critical for muscle endurance due to its role in the regulation of fatty acid oxidation. The 5'-AMP-activated protein kinase (AMPK) is an energy sensor in cells, but its role in PPARα regulation in vivo remains unknown. In this study, we examined PPARα expression in the skeletal muscle of AMPKα2 overexpression (OE), knockout (KO) and wild-type (WT) mice after four weeks of exercise under intermittent hypoxia. WT, OE and KO mice were used at 40 mice/strain and randomly subdivided into four subgroups: control (C), running (R), hypoxia (H), and running plus hypoxia (R+H) at 10 mice/group. The treadmill running was performed at the speed of 12 m/min, 60 min/day with a slope of 0 degree for four weeks. The hypoxia treatment was performed in daytime with normobaric hypoxia (11.20% oxygen, 8 hours/day). In the R+H group, the treadmill running was conducted in the hypoxic condition. AMPKα2, phosphor-AMPKα (p-AMPKα) (Thr172), nuclear PPARα proteins were measured by Western blot and the medium chain acyl coenzyme A dehydrogenase (MCAD) mRNA, the key enzyme for fatty acid oxidation and one of the PPARα target genes, was also measured in skeletal muscles after the interventions. The results showed that nuclear PPARα protein was significantly increased by R+H in WT muscles, the increase was enhanced by 41% (p<0.01) in OE mice, but was reduced by 33% (p<0.01) in KO mice. The MCAD mRNA expression was increased after four weeks of R+H intervention. The change in MCAD mRNA followed a similar trend as that of PPARα protein in OE and KO mice. Our data suggest that the increase in nuclear PPARα protein by four-week exercise training under the intermittent hypoxia was dependent on AMPK activation.
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Affiliation(s)
- Ge Li
- Division of Exercise Biochemistry, Institute of Sports Science, Beijing Sport University, China
| | - Jianxiong Wang
- School of Health and Wellbeing, Faculty of Health, Engineering, and Sciences, University of Southern Queensland, Australia
| | - Jianping Ye
- Pennington Biomedical Research Center, Louisiana State University, Louisiana, United States of America
| | - Yimin Zhang
- Key Laboratory of Exercise and Physical Fitness (Beijing Sport University), Ministry of Education of the People’s Republic of China
| | - Ying Zhang
- Division of Exercise Biochemistry, Institute of Sports Science, Beijing Sport University, China
- * E-mail:
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Abstract
Abnormalities in myocardial substrate metabolism play a central role in the manifestations of most forms of cardiac disease such as ischemic heart disease, heart failure, hypertensive heart disease, and the cardiomyopathy due to either obesity or diabetes mellitus. Their importance is exemplified by both the development of numerous imaging tools designed to detect the specific metabolic perturbations or signatures related to these different diseases, and the vigorous efforts in drug discovery/development targeting various aspects of myocardial metabolism. Since the prior review in 2005, we have gained new insights into how perturbations in myocardial metabolism contribute to various forms of cardiac disease. For example, the application of advanced molecular biologic techniques and the development of elegant genetic models have highlighted the pleiotropic actions of cellular metabolism on energy transfer, signal transduction, cardiac growth, gene expression, and viability. In parallel, there have been significant advances in instrumentation, radiopharmaceutical design, and small animal imaging, which now permit a near completion of the translational pathway linking in-vitro measurements of metabolism with the human condition. In this review, most of the key advances in metabolic imaging will be described, their contribution to cardiovascular research highlighted, and potential new clinical applications proposed.
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Affiliation(s)
- Robert J Gropler
- Division of Radiological Sciences, Cardiovascular Imaging Laboratory, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway, St. Louis, MO, 63110, USA,
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Banz WJ, Davis J, Steinle JJ, Adler S, Oitker J, Winters TA, Higginbotham DA, Hou Y, Henry N, Peterson R, Meyers CY. (+)-Z-Bisdehydrodoisynolic Acid Ameliorates Obesity and the Metabolic Syndrome in Female ZDF Rats. ACTA ACUST UNITED AC 2012; 13:1915-24. [PMID: 16339123 DOI: 10.1038/oby.2005.236] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE The putative selective estrogen receptor modulator (+)-Z-bisdehydrodoisynolic acid (Z-BDDA) has been found to improve cardiovascular risk in rodents. The objective of this study was to investigate the effectiveness of (+)-Z-BDDA compared with the antidiabetic drug, rosiglitazone, in treating obesity and risk factors associated with the metabolic syndrome. RESEARCH METHODS AND PROCEDURES Female Zucker Diabetic Fatty rats were randomly assigned to three treatment groups for 29 weeks: control (C), 1.8 mg (+)-Z-BDDA/kg diet [control diet + (+)-Z-BDDA (CB)], or 100 mg rosiglitazone/kg diet [control diet + rosiglitazone (CR)]. At sacrifice, physiological, biochemical, and molecular parameters were examined. RESULTS CB animals gained less weight and exhibited a decrease in total body lipids (p < 0.05) as compared with C or CR rats. Body weight and total body lipids were the highest in CR rats (p < 0.05). Liver weights in CB and CR rats were lower (p < 0.05) than in C rats, whereas kidney weights were lower in CB (p < 0.05) than in C and CR animals. Fasting plasma glucose was lower (p < 0.05) in the CB and CR animals when compared with C animals. C rats exhibited the highest concentration of total plasma cholesterol, and CR-treated rats exhibited the lowest concentration. Plasma triglycerides followed the same pattern as plasma cholesterol. Histomorphometry of heart vasculature revealed that CB and CR treatments produced a significant shift from small to large venules and arterioles compared with C (p < 0.05). Liver expression profiles of peroxisome proliferator-activated receptor (PPAR) alpha, PPARgamma, and PPAR-regulated genes revealed encouraging CB-induced effects. DISCUSSION These results suggest that (+)-Z-BDDA may have applications in treating obesity and complications associated with the metabolic syndrome.
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Affiliation(s)
- William J Banz
- Department of Animal Science, Food, and Nutrition, Southern Illinois University, Carbondale, IL 62901-4317, USA.
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Zhang J, Hu R, Xia ZK, Ren XG, Zhang LW, Liang YH, Liu GL. Protective effects of sinomenine against doxorubicin-induced nephrosis in rats. J Asian Nat Prod Res 2012; 14:678-687. [PMID: 22582804 DOI: 10.1080/10286020.2012.685070] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Sinomenine (SN, 1) is a pure compound extracted from the Sinomenium acutum plant. We investigated the protective effects and mechanism of action of SN in a rat model of doxorubicin (DOX)-induced nephrosis. Nephrosis was induced by a single dose of 5 mg/kg DOX, and DOX-treated rats received a daily i.p. injection of 10 or 30 mg/kg SN, or saline (n = 6). Urine and serum biochemical parameters, serum TNF-α and IL-1β levels, nephrin, podocin, α-actinin-4, and peroxisome proliferator-activated receptor-α (PPAR-α) protein expression, and renal ultrastructure were examined at day 28. Compound 1 significantly attenuated the effect of DOX on urine and serum biochemical parameters. Electron microscopy demonstrated that 1 suppressed DOX-induced increases in foot process width. Compared with those in control rats, nephrin, podocin, and PPAR-α protein expressions decreased in the glomeruli of DOX-treated rats, and this effect was significantly attenuated by 1. However, no appreciable alterations were observed in the expression level of α-actinin-4. DOX significantly increased serum TNF-α and IL-1β compared with those in control rats, and 1 significantly reduced the serum levels of TNF-α and IL-1β. SN ameliorates DOX-induced nephrotic syndrome in rats, resulting in a modulation of renal nephrin, podocin expression, and thereby protecting podocytes from injury.
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Affiliation(s)
- Jie Zhang
- Department of Pediatrics, Jingling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
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Cho HK, Kong HJ, Kim HY, Cheong J. Characterization of Paralichthys olivaceus peroxisome proliferator-activated receptor-α gene as a master regulator of flounder lipid metabolism. Gen Comp Endocrinol 2012; 175:39-47. [PMID: 22051321 DOI: 10.1016/j.ygcen.2011.08.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 08/17/2011] [Accepted: 08/19/2011] [Indexed: 01/10/2023]
Abstract
Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that play key roles in lipid and energy homeostasis. Paralichthys olivaceus PPARα (PoPPARα) cDNA was isolated by initial reverse transcription-polymerase chain reaction (RT-PCR) using conserved region among fish species and rapid amplification of cDNA ends (RACE). The full-length of PoPPARα cDNA is 2040-bp long encoding a polypeptide with 505 amino acids and containing a DNA binding domain (C4-type zinc finger) and a ligand-binding domain. PoPPARα was detected from 1 day post-hatch and was highly expressed in the stomach, liver, and intestine of continuously fed flounder, approximately 16 cm in size. PoPPARα mRNA expression was down-regulated in the kidney, stomach, and liver of the 4.5-month-old flounder after a 30 day food-deprivation period. PoPPARα activates the PPAR response element (PPRE)-driven reporter, and treatment with Wy14643, a PPARα agonist, augmented PoPPARα-stimulated peroxisome proliferator response element activity in HINAE and HepG2 cells. PoPPARα activated the expression of fatty acid β-oxidation related genes such as carnitine palmitoyltransferase 1A, medium chain acyl-CoA dehydrogenase, and acyl-CoA oxidase 1 and inhibited the expression of sterol regulatory element binding protein and fatty acid synthase by competitively inhibiting LXR/RXR heterodimer formation. These results suggest that PoPPARα plays an important role in lipid metabolism of olive flounder and that it is functionally and evolutionarily conserved in olive flounder and mammals.
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Affiliation(s)
- Hyun Kook Cho
- Dept of Molecular Biology, Pusan National University, Busan 609-735, Republic of Korea
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Sjölander A, Minthon L, Bogdanovic N, Wallin A, Zetterberg H, Blennow K. The PPAR-α gene in Alzheimer's disease: Lack of replication of earlier association. Neurobiol Aging 2009; 30:666-8. [PMID: 17850927 DOI: 10.1016/j.neurobiolaging.2007.07.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Accepted: 07/26/2007] [Indexed: 11/29/2022]
Abstract
Recently, a single nucleotide polymorphism (SNP, rs1800206) in the peroxisome proliferator-activated receptor alpha (PPAR-alpha) gene has been proposed to be associated with Alzheimer's disease (AD). To verify this finding, we analyzed the PPAR-alpha SNP in 461 patients with AD and 1395 controls. In subgroups, PPAR-alpha gene data could be investigated in relation to biochemical and neuropathological markers for AD. We found no significant differences in genotype or allele distributions between AD patients and controls. None of the PPAR-alpha gene variants influenced markers for AD.
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Affiliation(s)
- Annica Sjölander
- Department of Clinical Neuroscience, Unit of Neurochemistry, The Sahlgrenska Academy at Göteborg University, Sweden.
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Yasari S, Wang D, Prud'homme D, Jankowski M, Gutkowska J, Lavoie JM. Exercise training decreases plasma leptin levels and the expression of hepatic leptin receptor-a, -b, and, -e in rats. Mol Cell Biochem 2008; 324:13-20. [PMID: 19082917 DOI: 10.1007/s11010-008-9979-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 11/28/2008] [Indexed: 11/26/2022]
Abstract
In addition to acting in the central nervous system, leptin also acts on peripheral tissues such as liver to provide a protection against lipid accretion. Previous evidence from human and animal model indicates that exercise training reduces circulating leptin levels beyond the changes in adiposity levels. Because liver is one of the main peripheral organs for leptin action, this present study was designed to determine whether leptin receptors expression in liver is changed by exercise training. Female rats trained (TR) or kept sedentary (Sed) for 8 weeks were submitted either to a standard (SD) diet for 8 weeks or for 6 weeks followed by 2 weeks of high-fat (HF) or high-carbohydrate (HC) feeding. Food intake, adiposity levels, circulating plasma leptin and insulin concentrations along with the hepatic expression of leptin receptors (ObR-a, -b, and -e) and peroxisome proliferator-activated receptor alpha (PPARalpha) and peroxisome proliferator-activated receptor-gamma co-activator-1alpha (PGC-1alpha), were measured in all the animals. Intra-abdominal fat depots were increased under the HF but not under the HC diet. As expected, exercise training decreases intra-abdominal adiposity in animals fed with the SD and the HF diet, and to a lesser extent in HC-fed rats. Plasma leptin levels either expressed in absolute values or in values relative to adiposity levels were significantly (P < 0.05) increased with the HF diet and significantly decreased in TR animals, independently of the diet. Moreover, a significant (P < 0.01) reduction in hepatic gene expression of ObR-a, -b and -e was found in TR animals in all the three diet conditions. PPARalpha and PGC-1alpha mRNAs were also decreased (P < 0.05) in TR animals in two out of three diet conditions. The present findings indicate that exercise training-induced decrease in plasma leptin levels is accompanied by a reduction in gene expression of three different isoforms of leptin receptors in liver.
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Affiliation(s)
- Siham Yasari
- Department of Kinesiology, University of Montreal, Montreal, Canada.
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13
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Lee YA, Cho EJ, Yokozawa T. Effects of proanthocyanidin preparations on hyperlipidemia and other biomarkers in mouse model of type 2 diabetes. J Agric Food Chem 2008; 56:7781-7789. [PMID: 18690694 DOI: 10.1021/jf800639m] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The protective effect of proanthocyanidins from persimmon peel, using both oligomers and polymers, was investigated in a db/db type 2 diabetes model. Male db/db mice were divided into three groups: control (vehicle), polymer-, or oligomer- (10 mg/(kg body weight x day x p.o.)) administered mice. Age-matched nondiabetic m/m mice were used as a normal group. The administration of proanthocyanidins reduced hyperglycemia in db/db mice through a decline in the serum level of glucose and glycosylated protein. In addition, it had a strong effect on hyperlipidemia through lowering levels of triglyceride, total cholesterol, and nonesterified fatty acids. The protective effect against hyperglycemia and hyperlipidemia was greater in the groups administered the oligomeric rather than polymeric form. The increased oxidative stress in db/db mice was attenuated by the administration of oligomers through inhibiting the generation of reactive oxygen species and lipid peroxidation and elevating the reduced glutathione/oxidized glutathione ratio. On the other hand, polymers did not show such an effect. Moreover, expressions in the liver of sterol regulatory element binding protein (SREBP)-1 and SREBP-2 were downregulated by the administration of proanthocyanidins, especially the oligomeric form. Oligomers caused a slight elevation in the expression of peroxisome proliferator-activated receptors alpha. Furthermore, oligomeric proanthocyanidin regulated the expression of nuclear factor kappaB in db/db type 2 diabetes via the activation of inhibitor protein kappaB-alpha. It also attenuated the protein expressions of cyclooxygenase-2 and inducible nitric oxide synthase. This suggests that oligomers would act as a regulator in inflammatory reactions associated with oxidative stress in type 2 diabetes. The present study results suggest that proanthocyanidin administration, especially the oligomeric form, may improve oxidative stress via the regulation of hyperlipidemia than hyperglycemia in type 2 diabetes.
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Affiliation(s)
- Young A Lee
- Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
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14
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Abstract
Liver fatty acid metabolism of male rats fed on a vitamin A-deficient diet for 3 months from 21 d of age was evaluated. Vitamin A restriction produced subclinical plasma and negligible liver retinol concentrations, compared with the control group receiving the same diet with 4000 IU vitamin A (8 mg retinol as retinyl palmitate)/kg diet. Vitamin A deficiency induced a hypolipidaemic effect by decreasing serum triacylglycerol, cholesterol and HDL-cholesterol levels. The decrease of liver total phospholipid was associated with low phosphatidylcholine synthesis observed by lower [14C]choline incorporation into phosphatidylcholine, compared with control. Also, liver fatty acid synthesis decreased, as was indicated by activity and mRNA expression of acetyl-CoA carboxylase (ACC), and incorporation of [14C]acetate into saponified lipids. A decrease of the PPARalpha mRNA expression was observed. Liver mitochondria of vitamin A-deficient rats showed a lower total phospholipid concentration coinciding with a decrease of the cardiolipin proportion, without changes in the other phospholipid fractions determined. The mitochondria fatty acid oxidation increased by 30 % of the control value and it was attributed to a high activity and mRNA expression of carnitine palmitoyltransferase-I (CPT-I). An increase in serum beta-hydroxybutyrate levels was observed in vitamin A-deficient rats. Vitamin A deficiency alters the mitochondria lipid composition and also enhances fatty acid oxidation by modifying the production of malonyl-CoA, the endogenous inhibitor of CPT-I, due to decreased activity of liver ACC. The incorporation of vitamin A into the diet of vitamin A-deficient rats reverted all the changes observed.
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Affiliation(s)
- Liliana B Oliveros
- Laboratory of Biological Chemistry, Faculty of Chemistry, Biochemistry and Pharmacy, National University of San Luis, Avenida Ejército de los Andes 954, 5700 San Luis, Argentina
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15
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Teunissen BEJ, Smeets PJH, Willemsen PHM, De Windt LJ, Van der Vusse GJ, Van Bilsen M. Activation of PPARdelta inhibits cardiac fibroblast proliferation and the transdifferentiation into myofibroblasts. Cardiovasc Res 2007; 75:519-29. [PMID: 17543901 DOI: 10.1016/j.cardiores.2007.04.026] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 04/20/2007] [Accepted: 04/26/2007] [Indexed: 10/23/2022] Open
Abstract
OBJECTIVE The development of heart failure is invariably associated with extensive fibrosis. Treatment with Peroxisome Proliferator-Activated Receptor (PPAR) ligands has been shown to attenuate cardiac fibrosis, but the molecular mechanism underlying this protective effect has remained largely unknown. In this study the potential of each PPAR isoform (PPARalpha, delta, and gamma) to attenuate cardiac fibroblast proliferation, fibroblast (CF) to myofibroblast (CMF) transdifferentiation, and collagen synthesis was investigated. METHODS AND RESULTS PPARdelta was found to be the most abundant isoform in both CF and CMF. Only the PPARdelta ligand GW501516, but not PPARalpha ligand Wy-14,643 or PPARgamma ligand rosiglitazone, significantly increased PPAR-dependent promoter activity and expression of the PPAR-responsive gene UCP2 ( approximately 5-fold). GW501516 reduced the proliferation rate of CF (-38%) and CMF (-26%), which was associated with increased expression of the cell cycle inhibitor gene G0/G1 switch gene 2 (G0S2). Exposure of CF to the PPARdelta ligand or adenoviral overexpression of PPARdelta significantly decreased alpha-smooth muscle actin (alpha-SMA) levels, indicating a reduced CF to CMF transition. The inhibition of transdifferentiation by PPARdelta correlated with an increase in PTEN (Phosphatase and Tensin Homolog Deleted on Chromosome ten) expression. (3)H-Proline incorporation assays demonstrated a GW501516 induced decline in collagen synthesis (-36%) in CF. CONCLUSION Cardiac fibroblast proliferation, fibroblast to myofibroblast differentiation and collagen synthesis were reduced after activation of PPARdelta, suggesting that PPARdelta represents an attractive molecular target for attenuating cardiac fibrosis.
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Affiliation(s)
- Birgit E J Teunissen
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
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16
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Buono S, Cristiano L, D'Angelo B, Cimini A, Putti R. PPARalpha mediates the effects of the pesticide methyl thiophanate on liver of the lizard Podarcis sicula. Comp Biochem Physiol C Toxicol Pharmacol 2007; 145:306-14. [PMID: 17329170 DOI: 10.1016/j.cbpc.2006.12.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 12/15/2006] [Accepted: 12/29/2006] [Indexed: 12/01/2022]
Abstract
The majority of environmental pollutants are potential peroxisomal proliferators which include a heterogeneous group of compounds known to determine massive peroxisomal proliferation and hepatocarcinogenesis in rodents. Peroxisomal proliferation is accompanied by the induction of the peroxisomal fatty acid beta-oxidation pathway mediated by a class of transcription factors named peroxisome proliferators activated receptors (PPARs). This phenomenon demonstrated also in ectotherm animals after exposition to environmental pollutants may be utilized as biomarker in environmental impact studies. In the present work we have tested the sensitivity to methyl thiophanate (TM) of the lizard Podarcis sicula in order to propose a biological model for monitoring the ecotoxicological effects of this pesticide on terrestrial sentinel species. The data obtained demonstrate that exposition to sub-lethal concentrations of TM leads to hepatocellular morphological changes and glycogen depletion, apoptosis, as well as probable peroxisomal proliferation attested by the increase of acyl-CoA oxidase (AOX). This effect seems to be mediated by the concomitant increase of PPARalpha. On the basis of these results we propose that also in Podarcis sicula, as just proposed for aquatic organisms, peroxisomal proliferation and AOX increase may be considered new biomarkers to evaluate pollution by organic compound in terrestrial environments.
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Affiliation(s)
- S Buono
- Department of Biological Sciences, University Federico II Naples, via Mezzocannone n. 8, Italy
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17
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Dubrac S, Stoitzner P, Pirkebner D, Elentner A, Schoonjans K, Auwerx J, Saeland S, Hengster P, Fritsch P, Romani N, Schmuth M. Peroxisome Proliferator-Activated Receptor-α Activation Inhibits Langerhans Cell Function. J Immunol 2007; 178:4362-72. [PMID: 17371993 DOI: 10.4049/jimmunol.178.7.4362] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Epidermal Langerhans cells (LC) play a pivotal role in initiating and maintaining primary immune responses in the skin. In the present study, we asked whether peroxisome proliferator-activated receptor-alpha (PPARalpha) activation modulates LC function. Our results show that PPARalpha is expressed in immature LC and is down-regulated in mature LC suggesting that an early decrease of PPARalpha expression in LC may allow them to mature after contact with an Ag. We further show that pharmacologic PPARalpha activation inhibits LC maturation, migratory capacity, cytokine expression, and the ability to drive T cell proliferation. Moreover, PPARalpha activation inhibits NF-kappaB but not stress-activated protein kinase/JNK, p38MAPK, and ERK1/2. In conclusion, PPARalpha activation by endogenous ligands may provide a molecular signal that allows LC to remain in an immature state within the epidermis for extended periods of time despite minor environmental stimuli.
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Affiliation(s)
- Sandrine Dubrac
- Department of Dermatology, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria.
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18
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Park CW, Kim HW, Ko SH, Lim JH, Ryu GR, Chung HW, Han SW, Shin SJ, Bang BK, Breyer MD, Chang YS. Long-term treatment of glucagon-like peptide-1 analog exendin-4 ameliorates diabetic nephropathy through improving metabolic anomalies in db/db mice. J Am Soc Nephrol 2007; 18:1227-38. [PMID: 17360951 DOI: 10.1681/asn.2006070778] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is a gut incretin hormone and is a new clinically available class of agents for improving of insulin resistance in both animals and humans with type 2 diabetes. These studies aimed to determine whether long-term treatment with a long-acting GLP-1 analog, exendin-4, delayed the progression of diabetes. Male db/db mice and db/m mice at 8 wk of age were treated with exendin-4 for 8 wk, whereas the control db/db mice received only vehicle. Urinary albumin excretion was significantly decreased in db/db mice that were treated with 1 nmol/kg exendin-4 compared with those in db/db mice that were treated with 0.5 nmol/kg exendin-4 and control db/db mice (P < 0.005). Intraperitoneal glucose tolerance test was improved in db/db mice that were treated with 1 nmol/kg exendin-4 compared with other groups (P < 0.05). Despite this, fasting blood glucose, glycated hemoglobin, and creatinine concentrations were not significantly different among db/db mice. Renal histology studies further demonstrated that glomerular hypertrophy, mesangial matrix expansion, TGF-beta1 expression, and type IV collagen accumulation and associated glomerular lipid accumulation were significantly decreased in db/db mice that were treated with 1 nmol/kg exendin-4. Furthermore, there were fewer infiltrating inflammatory cells and apoptotic cells in the glomeruli of db/db mice that were treated with 1 nmol/kg exendin-4 compared with those in the other groups accompanied by an increase in the renal immunoreactivity of peroxisome proliferator-activated receptor alpha and GLP-1 receptor-positive cells and a decrease in 24-h urinary 8-hydroxy-deoxyguanosine levels (P < 0.01, respectively) along with decreases in lipid content. Taken together, exendin-4 treatment seems to ameliorate diabetic nephropathy together with improvement of the metabolic anomalies. These results suggest that exendin-4 could provide a therapeutic role in diabetic nephropathy that results from type 2 diabetes.
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Affiliation(s)
- Cheol Whee Park
- Division of Nephrology, Department of Internal Medicine, The Catholic University of Korea, #62 Yoido-Dong, Youngdungpo-Ku, Seoul, Korea 150-713
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19
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Yakubu MA, Nsaif RH, Oyekan AO. peroxisome proliferator-activated receptor alpha activation-mediated regulation of endothelin-1 production via nitric oxide and protein kinase C signaling pathways in piglet cerebral microvascular endothelial cell culture. J Pharmacol Exp Ther 2006; 320:774-81. [PMID: 17105827 PMCID: PMC4502983 DOI: 10.1124/jpet.106.104992] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elevated endothelin (ET)-1 has been implicated in cerebrovascular complications following brain trauma characterized by dysregulation of endothelial nitric oxide synthase (eNOS), protein kinase C (PKC), and cerebral function. Recently, vascular expression of PPARalpha has been observed and suggested to improve vascular dysfunction. We speculate that activation of PPARalpha in cerebral microvessels can improve cerebral dysfunction following trauma, and we tested the hypothesis that activation of cerebral endothelial peroxisome proliferator-activated receptor (PPAR)alpha will attenuate ET-1 production via a mechanism involving nitric oxide (NO) and PKC. Phorbol 12-myristate 13-acetate (PMA) (1 microM), bradykinin (BK, 1 microM), angiotensin II (AII, 1 microM), or hemoglobin (Hem, 10 microM) increased ET-1 levels by 24-, 11.4-, 3.6-, or 1.3-fold increasing ET-1 levels from 0.36 +/- 0.08 to 8.6 +/- 0.8, 4.1 +/- 0.7, 1.30 +/- 0.1, or 0.47 +/- 0.03 fmol/microg protein (p < 0.05), respectively. Clofibrate (10 microM) reduced basal ET-1 from 0.36 +/- 0.08 (control) to 0.03 +/- 0.01 and blunted vasoactive agent-induced increase to 0.12 +/- 0.07 (PMA), 0.6 +/- 0.04 (BK), 0.25 +/- 0.03 (AII), or 0.12 +/- 0.03 (Hem) fM/microg protein (p < 0.05). L-arginine methyl ester (100 microM) inhibited clofibrate-induced reduction in basal ET-1 production. Clofibrate increased PPARalpha expression, accompanied by increased NO production and eNOS expression. PKC inhibition by calphostin C (10 microM) blocked these effects, whereas activation by PMA reduced basal PPARalpha expression. Thus, PPARalpha activation attenuated ET-1 production by agents that mediate brain injury through mechanisms that probably result from PPARalpha-induced increase in eNOS expression/NO production and complex PKC signaling pathways. Therefore, PPARalpha activators can be appropriate therapeutic agents to alleviate cerebrovascular dysfunction following cerebral vasospasm.
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Affiliation(s)
- Momoh A Yakubu
- Vascular Biology Unit, Center for Cardiovascular Diseases, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX 77004, USA.
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20
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Kudo T, Asano J, Shimizu T, Nanashima N, Fan Y, Akita M, Ookawa K, Hayakari M, Yokoyama Y, Suto K, Tsuchida S. Different susceptibility to peroxisome proliferator-induced hepatocarcinogenesis in rats with polymorphic glutathione transferase genes. Cancer Sci 2006; 97:703-9. [PMID: 16800819 DOI: 10.1111/j.1349-7006.2006.00247.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Although peroxisomal bifunctional enzyme (enoyl-CoA hydratase/L-3-hydroxyacyl-CoA dehydrogenase; BE) is a positive marker for peroxisome proliferation, it is completely absent or expressed very weakly in rat hepatic preneoplastic and neoplastic lesions induced by peroxisome proliferators (PP). After administration of PP for 8-15 weeks, some rats exhibit BE-negative preneoplastic foci but other rats do not. In the present study, to investigate the involvement of glutathione S-transferase (GST) M1 gene polymorphism in interindividual differences in susceptibility to PP, we developed a method to determine the genotypes of rats. We then examined whether rats with one type encoding 198Asn-199Cys (NC-type) or another encoding 198Lys-199Ser (KS-type) exhibit differences in clofibrate (CF) susceptibility. After administration of 0.3% CF for 6 weeks or more, BE-negative foci were found immunohistochemically in KS/KS-type rats, but not in NC/NC-type rats. The number of BE-negative foci in KS/KS rats was 15.3 +/- 9.0 foci/cm2 of liver section after 6 weeks of CF administration, and the values did not alter thereafter. The mean areas of BE-negative foci in KS/KS rat livers increased during the period from 6 to 60 weeks. At weeks 30 and 60, almost all BE-negative foci exhibited a clear cell phenotype, a type of preneoplastic hepatic lesion. BE-negative foci were devoid of peroxisome proliferator-activated receptor alpha, whereas surrounding tissues were positive for the receptor. These results indicate that rats that are polymorphic for the GST M1 gene exhibit different susceptibilities to CF in vivo.
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Affiliation(s)
- Toshihiro Kudo
- Second Department of Biochemistry, Hirosaki University School of Medicine, 5 Zaifu- cho, Hirosaki 036-8562, Japan
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21
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Park CW, Zhang Y, Zhang X, Wu J, Chen L, Cha DR, Su D, Hwang MT, Fan X, Davis L, Striker G, Zheng F, Breyer M, Guan Y. PPARα agonist fenofibrate improves diabetic nephropathy in db/db mice. Kidney Int 2006; 69:1511-7. [PMID: 16672921 DOI: 10.1038/sj.ki.5000209] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Peroxisome proliferator-activated receptor alpha (PPARalpha) is a member of the ligand-activated nuclear receptor superfamily, and plays an important role in lipid metabolism and glucose homeostasis. The purpose of this study is to determine whether the activation of PPARalpha by fenofbrate would improve diabetes and its renal complications in type II diabetes mellitus. Male C57 BLKS db/db mice and db/m controls at 8 weeks of age were divided to receive either a regular diet chow (db/db, n=8; db/m, n=6) or a diet containing fenofibrate (db/db, n=8; db/m, n=7). Mice were followed for 8 weeks. Fenofibrate treatment dramatically reduced fasting blood glucose (P<0.001) and HbA1c levels (P<0.001), and was associated with decreased food intake (P<0.01) and slightly reduced body weight. Fenofibrate also ameliorated insulin resistance (P<0.001) and reduced plasma insulin levels (P<0.05) in db/db mice. Hypertrophy of pancreatic islets was decreased and insulin content markedly increased (P<0.05) in fenofibrate-treated diabetic animals. In addition, fenofibrate treatment significantly reduced urinary albumin excretion (P<0.001). This was accompanied by dramatically reduced glomerular hypertrophy and mesangial matrix expansion. Furthermore, the addition of fenofibrate to cultured mesangial cells, which possess functional active PPARalpha, decreased type I collagen production. Taken together, the PPARalpha agonist fenofibrate dramatically improves hyperglycemia, insulin resistance, albuminuria, and glomerular lesions in db/db mice. The activation of PPARalpha by fenofibrate in mesangial cells may partially contribute to its renal protection. Thus, fenofibrate may serve as a therapeutic agent for type II diabetes and diabetic nephropathy.
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Affiliation(s)
- C W Park
- Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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22
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Cheng Y, Dharancy S, Malapel M, Desreumaux P. Hepatitis C virus infection down-regulates the expression of peroxisome proliferator-activated receptor alpha and carnitine palmitoyl acyl-CoA transferase 1A. World J Gastroenterol 2006; 11:7591-6. [PMID: 16437683 PMCID: PMC4727219 DOI: 10.3748/wjg.v11.i48.7591] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM To elucidate the role of the peroxisome proliferator-activated receptor alpha (PPARalpha) and its target gene carnitine palmitoyl acyl-CoA transferase 1A (CPT1A) in the pathogenesis of hepatitis C virus (HCV) infection. METHODS Liver samples were collected from the patients with chronic HCV infection and controls. HepG2 cells were transfected with vector pEF352neo carrying. Two independent clones (clone N3 and N4) stably expressing HCV core protein were analyzed. Total RNA was extracted from cells and liver tissues. PPARalpha and CPT1A mRNAs were quantified by real-time polymerase chain reaction (PCR) using SYBR Green Master. Total extracted proteins were separated by polyacrylamide gel electrophoresis, and electroblotted. Membranes were incubated with the anti-PPARalpha antibody, then with a swine anti-rabbit IgG conjugated to horseradish peroxidase for PPARalpha. Protein bands were revealed by an enhanced chemiluminescence reaction for PPARalpha. For immunohistochemical staining of PPARalpha, sections were incubated with the primary goat polyclonal antibody directed against PPARalpha at room temperature. RESULTS Real-time PCR indicated that the PPARalpha level and expression level of CPT1A gene in hepatitis C patients lowered significantly as compared with the controls (1.8+/-2.8 vs 13+/-3.4, P = 0.0002; 1.1+/-1.5 vs 7.4+/-1, P = 0.004). Western blot results showed that the level of PPARalpha protein in the livers of hepatitis C patients was lower than that in controls (2.3+/-0.3 vs 3.6+/-0.2, P = 0.009). The immunohistochemical staining results in chronic hepatitis C patients indicated a decrease in PPARalpha staining in hepatocytes compared with those in the control livers. The in vitro studies found that in the N3 and N4 colon stably expressing HCV core protein, the PPARalpha mRNA levels were significantly lower than that in the controls. CONCLUSION The impaired intrahepatic PPARalpha expression is associated with the pathogenic mechanism in hepatic injury during chronic HCV infection. HCV infection reduced the expression of PPARalpha and CPT1A at the level of not only mRNAs but also proteins. PPARalpha plays an important role in the pathogenesis of chronic HCV infection, but the impaired function of this nuclear receptor in HCV infection needs further studies.
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Affiliation(s)
- Yang Cheng
- Institute of Liver Diseases, Shanghai University of TCM, Shanghai 201203, China.
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Zou Y, Li J, Lu C, Wang J, Ge J, Huang Y, Zhang L, Wang Y. High-fat emulsion-induced rat model of nonalcoholic steatohepatitis. Life Sci 2006; 79:1100-7. [PMID: 16624332 DOI: 10.1016/j.lfs.2006.03.021] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 03/08/2006] [Accepted: 03/09/2006] [Indexed: 12/11/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is emerging as a common medical problem. Nonalcoholic steatohepatitis (NASH) is the critical turning point at which NAFLD progresses to more advanced stages such as hepatic fibrosis, cirrhosis and even hepatocellular carcinoma. However, the study of the pathogenic or therapeutic factors involved in NASH has been hampered by the absence of a suitable experimental model. The aim of the present work was to establish a high-fat emulsion-induced rat model of NASH. Male Sprague-Dawley rats were fed a high-fat emulsion via gavage for 6 weeks. Animals were examined for weight gain, serum and hepatic biochemistry, insulin sensitivity, hepatic malondialdehyde (MDA), superoxide dismutase (SOD) and tissue morphology, as well as cytochrome P-450 2E1 (CYP2E1) and peroxisome proliferator-activated receptor alpha (PPARalpha) expression in the liver. The results showed that rats treated with high-fat emulsion became obese, demonstrated abnormal aminotransferase activity, hyperlipoidemia, hyperinsulinemia, hyperglycemia and insulin resistance. The model rats exhibited an increased concentration of serum TNF-alpha, total cholesterol (TC), triglyceride (TG), MDA and reduced SOD levels in the liver. Immunoblot analysis showed that the expression of CYP2E1 was increased, whereas PPARalpha was reduced in the NASH model rat liver. Moreover, morphological evaluation revealed that hepatic steatosis, inflammation and mitochondrial lesions were also reproduced in this model. In conclusion, a practical and repeatable new rat model of steatohepatitis was established by feeding with high-fat emulsion via gavage. This model provides a valuable research tool and reproduces many of the clinical indices of human NASH.
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Affiliation(s)
- Yuhong Zou
- Institute of Clinical Pharmacology, School of Pharmacy, Anhui Medical University, Heifei, 230032 Anhui Province, China.
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Goikoetxea MJ, Beaumont J, González A, López B, Querejeta R, Larman M, Díez J. Altered cardiac expression of peroxisome proliferator-activated receptor-isoforms in patients with hypertensive heart disease. Cardiovasc Res 2006; 69:899-907. [PMID: 16371224 DOI: 10.1016/j.cardiores.2005.11.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 10/19/2005] [Accepted: 11/10/2005] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE To investigate whether cardiac expression of the nuclear peroxisome proliferator-activated receptor alpha (PPARalpha) is altered in patients with hypertensive heart disease (HHD). METHODS We studied endomyocardial septal biopsies from 24 patients with essential hypertension divided into three groups: 6 without left ventricular hypertrophy (LVH) (HT group), 10 with LVH (LVH group), and 8 with LVH and heart failure (HF) (HF group). The expression of two PPARalpha isoforms (the native active and the truncated inhibitory) was analyzed by Western blot and reverse transcription polymerase chain reaction (RT-PCR), and two PPARalpha target genes were evaluated by RT-PCR. Histomorphological features were evaluated in a second myocardial sample from LVH and HF groups. RESULTS Whereas the expression of native PPARalpha protein was lower (p<0.05) in LVH and HF groups than in the HT group, truncated PPARalpha protein was overexpressed (p<0.001) in the HF group as compared with LVH and HT groups. The mRNA expression of native and truncated PPARalpha was similar in the three groups of hypertensives. In addition, a progressive decrease (p for trend<0.05) in the two PPARalpha target genes mRNA expression was observed among HT, LVH and HF groups. The amount of truncated PPARalpha protein correlates directly with cardiomyocytes apoptosis and inversely with cardiomyocytes density in patients with HHD. In addition, the expression of truncated PPARalpha protein was directly correlated with left ventricular volumes, and inversely with ejection fraction in all hypertensives. CONCLUSIONS These findings suggest that post-transcriptional regulation of PPARalpha isoforms is altered in patients with HHD, namely in those developing HF. An excess of the truncated inhibitory isoform may be involved in hypertensive left ventricular failure and remodeling.
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Affiliation(s)
- María J Goikoetxea
- Division of Cardiovascular Sciences, Centre for Applied Medical Research, University of Navarra, 31008 Pamplona, Spain
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Sanguino E, Roglans N, Alegret M, Sánchez RM, Vázquez-Carrera M, Laguna JC. Different response of senescent female Sprague-Dawley rats to gemfibrozil and rosiglitazone administration. Exp Gerontol 2006; 40:588-98. [PMID: 15998575 DOI: 10.1016/j.exger.2005.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Revised: 05/30/2005] [Accepted: 05/31/2005] [Indexed: 01/08/2023]
Abstract
Eighteen-month-old Sprague-Dawley rats present age-related alterations in lipid and glucose metabolism and are resistant to the effect of PPARalpha-activating hypolipidemic drugs, such as gemfibrozil. We tested if these animals were responsive to the administration of rosiglitazone, an insulin-sensitizer acting on PPARgamma. We determined in 18-month-old female Sprague-Dawley rats treated for 21 days with a daily dose of 3mg gemfibrozil/kg or 3mg rosiglitazone/kg: (i) plasma concentrations of total cholesterol (TC), triglycerides (TG), nonesterified fatty acids (NEFA), glucose, insulin and leptin, (ii) hepatic concentrations of TG, NEFA and cholesteryl esters (CE), and (iii) the liver expression and binding activity of peroxisome proliferator-activated receptor alpha (PPARalpha), and several of its target genes, hepatic nuclear factor-4 (HNF-4), and liver X receptor alpha (LXRalpha). Although gemfibrozil induced mild effects on hepatic PPARalpha, HNF-4, and LXRalpha, only rosiglitazone significantly reduced plasma TG (59%), glucose (19%), insulin (61%), and leptin (66%), and liver TG (43%), CE (49%), and NEFA (27%). These changes were associated to an increased body weight gain and a decrease in visceral fat (8.7-fold and 37% vs. control females, respectively). The beneficial effect of rosiglitazone treatment in 18-month-old female rats could be related to a direct effect on white adipose tissue.
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Affiliation(s)
- Elena Sanguino
- Unidad de Farmacología y Farmacognosia, Facultad de Farmacia, Universidad de Barcelona, Spain
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Compe E, Drané P, Laurent C, Diderich K, Braun C, Hoeijmakers JHJ, Egly JM. Dysregulation of the peroxisome proliferator-activated receptor target genes by XPD mutations. Mol Cell Biol 2005; 25:6065-76. [PMID: 15988019 PMCID: PMC1168804 DOI: 10.1128/mcb.25.14.6065-6076.2005] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutations in the XPD subunit of TFIIH give rise to human genetic disorders initially defined as DNA repair syndromes. Nevertheless, xeroderma pigmentosum (XP) group D (XP-D) patients develop clinical features such as hypoplasia of the adipose tissue, implying a putative transcriptional defect. Knowing that peroxisome proliferator-activated receptors (PPARs) are implicated in lipid metabolism, we investigated the expression of PPAR target genes in the adipose tissues and the livers of XPD-deficient mice and found that (i) some genes are abnormally overexpressed in a ligand-independent manner which parallels an increase in the recruitment of RNA polymerase (pol) II but not PPARs on their promoter and (ii) upon treatment with PPAR ligands, other genes are much less induced compared to the wild type, which is due to a lower recruitment of both PPARs and RNA pol II. The defect in transactivation by PPARs is likely attributable to their weaker phosphorylation by the cdk7 kinase of TFIIH. Having identified the phosphorylated residues in PPAR isotypes, we demonstrate how their transactivation defect in XPD-deficient cells can be circumvented by overexpression of either a wild-type XPD or a constitutively phosphorylated PPAR S/E. This work emphasizes that underphosphorylation of PPARs affects their transactivation and consequently the expression of PPAR target genes, thus contributing in part to the XP-D phenotype.
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Affiliation(s)
- Emmanuel Compe
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch Cedex, CU Strasbourg, France
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Orfila C, Lepert JC, Alric L, Carrera G, Béraud M, Pipy B. Immunohistochemical distribution of activated nuclear factor κB and peroxisome proliferator-activated receptors in carbon tetrachloride-induced chronic liver injury in rats. Histochem Cell Biol 2005; 123:585-93. [PMID: 15959796 DOI: 10.1007/s00418-005-0785-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/21/2005] [Indexed: 12/20/2022]
Abstract
We investigated the immunohistochemical distribution of active NF-kappaB p65 and peroxisome proliferator-activated receptor (PPAR) subtypes alpha and gamma in the different phases of liver steatonecrosis and cirrhosis induced in rats after 3 and 9 weeks of carbon tetrachloride (CCl4) intoxication. CCl4 treatment can induce changes in the expression of NF-kappaB and PPARs. Immunohistochemical analysis of liver tissue sections from rats with steatonecrosis or cirrhosis demonstrated a significant increase in the number of NF-kappaB-positive and TNF-alpha-positive hepatocytes and Kupffer cells. In healthy controls, no expression of active NF-kappaB was detected. In previous studies, we have demonstrated that Kupffer cells isolated from rats with CCl4-induced steatonecrosis produced more reactive oxygen intermediates than cells isolated from normal rats. These oxidants could activate NF-kappaB and lead to an overexpression of TNF-alpha, observed in liver tissue sections. After CCl4 ingestion, the rat livers demonstrated a significantly decreased number of hepatocytes expressing PPARalpha and PPARgamma and a significantly increased number of ED2-positive Kupffer cells expressing these transcription factors, compared to normal. The activation of the p65 isoform of NF-kappaB correlates negatively with transcription of the alpha and gamma isoforms of PPAR in hepatocytes, and positively in Kupffer cells. These results suggest that the regulation and the role of these two transcription factors differ in the two cell types studied.
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Shi RL, Zhao CX, Zhu HB, Yang Y, Wang SL, Jiang LL. [Relationship between the increase of hepatic D-bifunctional protein activity and bile acid biosynthesis in rats]. Zhongguo Yi Xue Ke Xue Yuan Xue Bao 2005; 27:321-4. [PMID: 16038268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
OBJECTIVE To determine the physiological role of D-bifunctional protein (DBP) in bile acid biosynthesis through investigating the effect of increasing activity of DBP on bile acid biosynthesis. METHODS Twenty male Wistar rats were divided into two groups: diethylhexyl phthalate (DEHP) group (n = 10) and control group (n = 10). Serum triglyceride, total cholesterol, hepatic DBP activity, and fecal bile acids were assayed. The mRNA levels of hepatic peroxisome proliferator-activated receptor alpha (PPARalpha), DBP, and cholesterol 7alpha-hydroxylase (CYP7A1) were detected by RT-PCR. RESULTS Compared with control group, serum triglyceride level was decreased significantly and PPARalphamRNA level was increased significantly in DEHP group (P < 0.01). Together with a sharp induction of DBP mRNA expression and DBP activity in DEHP group (P < 0.01), the levels of CYP7A1 mRNA and fecal bile acids were significantly increased by 1.9 times and 1.6 times respectively compared to control group (P < 0.01). There was a significantly positive correlation between DBP mRNA level or DBP activity and CYP7A1 mRNA level (r = 0.89, P < 0.01; r = 0.95, P < 0.01). CONCLUSION The up-regulation of DBP mRNA and activity in liver can result in the increase in CYP7A1 mRNA expression and bile acid biosynthesis, suggesting that DBP may be involved in bile acid biosynthesis together with CYP7A1.
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Affiliation(s)
- Ru-ling Shi
- Department of Biochemistry, Hebei Medical University, Shijiazhuang 050017, China
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29
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Abstract
Myoglobin is an important intracellular O2 binding hemoprotein in heart and skeletal muscle. Surprisingly, disruption of myoglobin in mice (myo-/-) resulted in no obvious phenotype and normal cardiac function was suggested to be mediated by structural alterations that tend to steepen the oxygen pressure gradient from capillary to mitochondria. Here we report that lack of myoglobin causes a biochemical shift in cardiac substrate utilization from fatty acid to glucose oxidation. Proteome and gene expression analysis uncovered key enzymes of mitochondrial beta-oxidation as well as the nuclear receptor PPAR to be downregulated in myoglobin-deficient hearts. Using FDG-PET we showed a substantially increased in vivo cardiac uptake of glucose in myo-/- mice (6.7+/-2.3 versus 0.8+/-0.5% of injected dose in wild-type, n=5, P<0.001), which was associated with an upregulation of the glucose transporter GLUT4. The metabolic switch was confirmed by 13C NMR spetroscopic isotopomer studies of isolated hearts which revealed that [1,6-13C2]glucose utilization was increased in myo-/- hearts (38+/-8% versus 22+/-5% in wild-type, n=6, P<0.05), and concomitantly, [U-13C16]palmitate utilization was decreased in the myoglobin-deficient group (42+/-6% versus 63+/-11% in wild-type, n=6, P<0.05). Because of the O2-sparing effect of glucose utilization, the observed shift in substrate metabolism benefits energy homoeostasis and therefore represents a molecular adaptation process allowing to compensate for lack of the cytosolic oxygen carrier myoglobin. Furthermore, our data suggest that an altered myoglobin level itself may be a critical determinant for substrate selection in the heart. The full text of this article is available online at http://circres.ahajournals.org.
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Affiliation(s)
- Ulrich Flögel
- Institut für Herz-und Kreislaufphysiologie, Heinrich-Heine-Universität Düsseldorf, Germany.
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Abstract
Peroxisome proliferator-activated receptor alpha (PPARalpha) is mainly expressed in liver and involved in lipid metabolism. Oxidation of certain fatty acids in peroxisomes is under PPARalpha control. A wide variety of lipid molecules activate PPARalpha as well as the fibric acid derivative clofibrate. In the present study, we evaluated the differential activation of PPARalpha with several agonist ligands through its expression and DNA binding in both rat (McA-RH7777) and human (HepG2) hepatoma cell lines. In McA-RH7777 cells, clofibrate alone mediated a higher induction of PPARalpha expression than linoleic acid. In contrast, linoleic acid was the most effective ligand in HepG2 cells and treatment with clofibrate plus linoleic acid did not further increase PPARalpha expression. PPRE-binding activity of PPARalpha in ligand-treated cells was also increased in a parallel manner. We suggest that ligand-induced PPARalpha activation might give rise to differential species-dependent responses.
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Affiliation(s)
- Filiz Akbiyik
- Hacettepe University Faculty of Medicine, Department of Biochemistry, Ankara, Turkey.
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Lai DY. Rodent carcinogenicity of peroxisome proliferators and issues on human relevance. J Environ Sci Health C Environ Carcinog Ecotoxicol Rev 2004; 22:37-55. [PMID: 15845221 DOI: 10.1081/gnc-120038005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A variety of substances such as hypolipidemic drugs, phthalate ester plasticizers, pesticides, and industrial solvents have been shown to increase the size and number of peroxisomes in rats and mice. They are grouped under the generic term peroxisome proliferators (PP) because of their unique property of inducing peroxisome proliferation. There are marked species differences in response to PP. Rats and mice are most sensitive, and hamsters show an intermediate response while guinea pigs, monkeys, and humans appear to be relatively insensitive or non-responsive at dose levels that produce a marked response in rodents. Out of over 100 PP identified to date, about 30 have been adequately tested and shown to be carcinogenic, inducing tumors (primarily in the liver) upon chronic administration to rats and/or mice; hence, chemicals which induce the proliferations of peroxisomes have formed a unique class of chemical carcinogens. It is not well documented that activation of the "peroxisome proliferator-activated receptor alpha" (PPARalpha) is involved in PP-induced liver growth and carcinogenesis in rodents. PPARalpha is also present in human cells; however, the levels reported are about 10% of those found in the liver of rodents. The human relevance of rodent tumors induced by PP has been the subject of debate over the last decade. Review of the existing evidence on PPAR-alpha agonists by a recent International Life Science Institute (ILSI) workgroup following a human relevance mode of action (MOA) framework has concluded that despite the presence of similar pathways in humans, it is unlikely that the proposed MOA for rodent tumors is plausible in humans, taking into account kinetic and dynamic factors. The data, however, did not permit a definitive conclusion that the animal MOA is not plausible in humans. While these agents appear unlikely to be hepatocarcinogens in humans at expected levels of human exposure, it remains uncertain to some experts in the field whether there is no possibility of carcinogenic potential under any circumstances of PP exposure, and if the potential human carcinogenicity of these chemicals can be summarily ignored. A number of remaining issues on human relevance of rodent tumors induced by PP are discussed.
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Affiliation(s)
- David Y Lai
- Office of Pollution Prevention and Toxics, Risk Assessment Division, US Environmental Protection Agency, Washington, DC 20460, USA.
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