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Abdalla MMI. Insulin resistance as the molecular link between diabetes and Alzheimer's disease. World J Diabetes 2024; 15:1430-1447. [DOI: 10.4239/wjd.v15.i7.1430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 04/08/2024] [Accepted: 05/06/2024] [Indexed: 07/08/2024] Open
Abstract
Diabetes mellitus (DM) and Alzheimer's disease (AD) are two major health concerns that have seen a rising prevalence worldwide. Recent studies have indicated a possible link between DM and an increased risk of developing AD. Insulin, while primarily known for its role in regulating blood sugar, also plays a vital role in protecting brain functions. Insulin resistance (IR), especially prevalent in type 2 diabetes, is believed to play a significant role in AD's development. When insulin signalling becomes dysfunctional, it can negatively affect various brain functions, making individuals more susceptible to AD's defining features, such as the buildup of beta-amyloid plaques and tau protein tangles. Emerging research suggests that addressing insulin-related issues might help reduce or even reverse the brain changes linked to AD. This review aims to explore the rela-tionship between DM and AD, with a focus on the role of IR. It also explores the molecular mechanisms by which IR might lead to brain changes and assesses current treatments that target IR. Understanding IR's role in the connection between DM and AD offers new possibilities for treatments and highlights the importance of continued research in this interdisciplinary field.
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Affiliation(s)
- Mona Mohamed Ibrahim Abdalla
- Department of Human Biology, School of Medicine, International Medical University, Bukit Jalil 57000, Kuala Lumpur, Malaysia
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Jang EJ, Lee DH, Im SS, Yee J, Gwak HS. Correlation between PPARG Pro12Ala Polymorphism and Therapeutic Responses to Thiazolidinediones in Patients with Type 2 Diabetes: A Meta-Analysis. Pharmaceutics 2023; 15:1778. [PMID: 37376225 DOI: 10.3390/pharmaceutics15061778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/09/2023] [Accepted: 06/16/2023] [Indexed: 06/29/2023] Open
Abstract
Background: Thiazolidinediones (TZDs) are a type of oral drug that are utilized for the treatment of type 2 diabetes mellitus (T2DM). They function by acting as agonists for a nuclear transcription factor known as peroxisome proliferator-activated receptor-gamma (PPAR-γ). TZDs, such as pioglitazone and rosiglitazone, help enhance the regulation of metabolism in individuals with T2DM by improving their sensitivity to insulin. Previous studies have suggested a relationship between the therapeutic efficacy of TZDs and the PPARG Pro12Ala polymorphism (C > G, rs1801282). However, the small sample sizes of these studies may limit their applicability in clinical settings. To address this limitation, we conducted a meta-analysis assessing the influence of the PPARG Pro12Ala polymorphism on the responsiveness of TZDs. Method: We registered our study protocol with PROSPERO, number CRD42022354577. We conducted a comprehensive search of the PubMed, Web of Science, and Embase databases, including studies published up to August 2022. We examined studies investigating the association between the PPARG Pro12Ala polymorphism and metabolic parameters such as hemoglobin A1C (HbA1C), fasting plasma glucose (FPG), triglyceride (TG), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and total cholesterol (TC). The mean difference (MD) and 95% confidence intervals (CIs) between pre- and post-drug administration were evaluated. The quality of the studies included in the meta-analysis was assessed by using the Newcastle-Ottawa Scale (NOS) tool for cohort studies. Heterogeneity across studies was assessed by using the I2 value. An I2 value greater than 50% indicated substantial heterogeneity, and a random-effects model was used for meta-analysis. If the I2 value was below 50%, a fixed-effects model was employed instead. Both Begg's rank correlation test and Egger's regression test were performed to detect publication bias, using R Studio software. Results: Our meta-analysis incorporated 6 studies with 777 patients for blood glucose levels and 5 studies with 747 patients for lipid levels. The included studies were published between 2003 and 2016, with the majority involving Asian populations. Five of the six studies utilized pioglitazone, while the remaining study employed rosiglitazone. The quality scores, as assessed with the NOS, ranged from 8 to 9. Patients carrying the G allele exhibited a significantly greater reduction in HbA1C (MD = -0.3; 95% CI = -0.55 to -0.05; p = 0.02) and FPG (MD = -10.91; 95% CI = -19.82 to -2.01; p = 0.02) levels compared to those with the CC genotype. Furthermore, individuals with the G allele experienced a significantly larger decrease in TG levels than those with the CC genotype (MD = -26.88; 95% CI = -41.30 to -12.46; p = 0.0003). No statistically significant differences were observed in LDL (MD = 6.69; 95% CI = -0.90 to 14.29; p = 0.08), HDL (MD = 0.31; 95% CI = -1.62 to 2.23; p = 0.75), and TC (MD = 6.4; 95% CI = -0.05 to 12.84; p = 0.05) levels. No evidence of publication bias was detected based on Begg's test and Egger's test results. Conclusions: This meta-analysis reveals that patients with the Ala12 variant in the PPARG Pro12Ala polymorphism are more likely to exhibit positive responses to TZD treatment in terms of HbA1C, FPG, and TG levels compared to those with the Pro12/Pro12 genotype. These findings suggest that genotyping the PPARG Pro12Ala in diabetic patients may be advantageous for devising personalized treatment strategies, particularly for identifying individuals who are likely to respond favorably to TZDs.
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Affiliation(s)
- Eun Jeong Jang
- College of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Republic of Korea
| | - Da Hoon Lee
- College of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Republic of Korea
| | - Sae-Seul Im
- Graduate School of Clinical Biohealth, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jeong Yee
- College of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Republic of Korea
| | - Hye Sun Gwak
- College of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Republic of Korea
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Angajala G, Aruna V, Pavan P, Guruprasad Reddy P. Biocatalytic one pot three component approach: Facile synthesis, characterization, molecular modelling and hypoglycemic studies of new thiazolidinedione festooned quinoline analogues catalyzed by alkaline protease from Aspergillus niger. Bioorg Chem 2021; 119:105533. [PMID: 34902647 DOI: 10.1016/j.bioorg.2021.105533] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 11/26/2021] [Accepted: 11/27/2021] [Indexed: 12/01/2022]
Abstract
A novel ANAP (Aspergillus niger from alkaline protease) catalyzed one pot three component approach in the synthesis of new thiazolidinedione festooned quinoline analogues via Knoevenagel condensation and N-alkylation have been reported. The catalytic effect of enzyme was monitored and optimized by adjusting various parameters including catalyst concentration, choice of solvent and temperature. The isolated alkaline protease exhibits favorable features for the reaction response such as the shorter reaction time, simple work-up procedure, clean reaction profiles and excellent product yields through reusability of the catalyst upto five cycles. In silico molecular docking simulations were carried out to find out the effective binding affinity of the synthesized quinoline analogues 4(a-i) towards PPARγ protein (Id-2XKW). In vitro α-amylase and α-glucosidase assays were performed for hypoglycemic activity evaluation. In vivo hypoglycemic studies carried out on streptozotocin (SZT) induced diabetic male albino rats have shown that compounds 4e and 4f significantly reduced blood glucose levels with percentage reduction of 43.7 ± 0.91 and 45.6 ± 0.28 at a concentration of 50 mg/kg body wt. The results obtained from molecular docking simulations and in vitro enzyme assays are in consistent with in-vivo studies which clearly demonstrated that out of the synthesized quinoline analogues, compounds 4e and 4f possess promising hypoglycemic activity which was on par to that of standards pioglitazone and rosiglitazone respectively.
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Affiliation(s)
- Gangadhara Angajala
- Department of Chemistry, Kalasalingam Academy of Research and Education, Anand nagar, Krishnankoil 626126, Tamilnadu, India.
| | - Valmiki Aruna
- Department of Chemistry, Kalasalingam Academy of Research and Education, Anand nagar, Krishnankoil 626126, Tamilnadu, India
| | - Pasupala Pavan
- Department of Humanities and Basic Sciences, G. Pulla Reddy Engineering College, Kurnool 518007, Andhra Pradesh, India
| | - Pulikanti Guruprasad Reddy
- School of Basic Sciences, Indian Institute of Technology Mandi, Kamand 175005, Himachal Pradesh, India; Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
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Angajala G, Aruna V, Pavan P, Reddy PG. Ultrasound promoted montmorillonite K-10 catalyzed synthesis, characterization, molecular modelling, SAR and hypoglycemic studies of new rhodanine bejeweled acridine analogues. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Shyur LF, Varga V, Chen CM, Mu SC, Chang YC, Li SC. Extract of white sweet potato tuber against TNF-α-induced insulin resistance by activating the PI3K/Akt pathway in C2C12 myotubes. BOTANICAL STUDIES 2021; 62:7. [PMID: 34003397 PMCID: PMC8131422 DOI: 10.1186/s40529-021-00315-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 05/11/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND White sweet potato (WSP; Ipomoea batatas L. Simon No. 1) has many potential beneficial effects on metabolic control and diabetes-related insulin resistance. The improvement of insulin resistance by WSP tuber extracts on glucose uptake were not investigated in C2C12 myoblast cells. RESULTS WSP tuberous ethanol extract (WSP-E) was partitioned with ethyl-acetate and water to obtain ethyl-acetate layer (WSP-EA) and water layer (WSP-EW). The WSP-EA shows the highest total phenolic contents and highest antioxidant activity by Folin-Ciocalteu and (2,2-diphenyl-1-picryl-hydrazyl-hydrate, DPPH) assay, respectively. After low concentration horse serum on differentiation inducement of C2C12 myoblasts into mature myotubes, the cells were treated with TNF-α to induce insulin resistance. WSP-EA and WSP-EW extracts increased the uptake of fluorescence glucose analogue (2-[N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino]-2-deoxy-D-glucose, 2-NBDG) in a dose-dependent manner as examined by flow cytometry. The WSP-EA enhanced glucose uptake by activation of phosphorylation of IR (pIR), IRS-1 (pIRS-1) and Akt (pAkt) involved in PI3K (phosphatidylinositol 3-kinase)/protein kinase B (Akt) pathway, also upregulated glucose transporter 4 (GLUT4) expression in myotubes. CONCLUSIONS WSP-EA enhanced the glucose uptake in C2C12 myotubes through upregulating the PI3K/Akt pathway. The in vitro data reveal that WSP tuber extracts has potential applications to improve insulin resistance in diabetes.
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Affiliation(s)
- Lie-Fen Shyur
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529 Taiwan
| | - Viola Varga
- School of Nutrition and Health Sciences, College of Nutrition, Taipei Medical University, 250 Wu-Hsing Street, Taipei, 11031 Taiwan
- Institute of Translational Medicine, Semmelweis University, 1094 Budapest, Hungary
| | - Chiao-Ming Chen
- Department of Food Science, Nutrition, and Nutraceutical Biotechnology, Shih Chien University, Taipei, 10462 Taiwan
| | - Shu-Chi Mu
- School of Medicine, Fu-Jen Catholic University, New Taipei City, 24205 Taiwan
| | - Yu-Chih Chang
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 115 Taiwan
| | - Sing-Chung Li
- School of Nutrition and Health Sciences, College of Nutrition, Taipei Medical University, 250 Wu-Hsing Street, Taipei, 11031 Taiwan
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An efficient Nano-Copper catalyzed base-free Knoevenagel condensation: A facile synthesis, molecular modelling simulations, SAR and hypoglycemic studies of new quinoline tethered acridine analogues as PPARγ agonists. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128601] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Dolegowska K, Marchelek-Mysliwiec M, Nowosiad-Magda M, Slawinski M, Dolegowska B. FGF19 subfamily members: FGF19 and FGF21. J Physiol Biochem 2019; 75:229-240. [PMID: 30927227 PMCID: PMC6611749 DOI: 10.1007/s13105-019-00675-7] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 03/12/2019] [Indexed: 02/07/2023]
Abstract
Fibroblast growth factors (FGF) constitute a large family of proteins with pleiotropic effects on development, organogenesis, and metabolism. The FGF19 subclass includes growth factors circulating with the blood referred to as endocrine FGF. Representatives of the FGF19 subclass, including FGF19, FGF21, and FGF23, act via FGFR receptors. The proteins of FGF19 subfamily influence the enterohepatic circulation of bile, participate in glucose and lipid metabolism regulation, and maintenance of phosphorus and vitamin D3 homeostasis. FGF19 and FGF21 are activated under different physiological and pathological conditions.
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Affiliation(s)
- Katarzyna Dolegowska
- Clinical Department of Nephrology, Transplantology, and Internal Medicine, Pomeranian Medical University, Szczecin, Poland
| | - Malgorzata Marchelek-Mysliwiec
- Clinical Department of Nephrology, Transplantology, and Internal Medicine, Pomeranian Medical University, Szczecin, Poland
| | - Monika Nowosiad-Magda
- Department of Immunology Diagnostics, Pomeranian Medical University, Szczecin, Poland
| | - Michal Slawinski
- Department of Laboratory Diagnostics, Independent Public Clinical Hospital No. 2, Pomeranian Medical University, Szczecin, Poland
| | - Barbara Dolegowska
- Department of Laboratory Diagnostics, Independent Public Clinical Hospital No. 2, Pomeranian Medical University, Szczecin, Poland.
- Department of Laboratory Medicine, Pomeranian Medical University, Szczecin, Poland.
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Nanjan MJ, Mohammed M, Prashantha Kumar BR, Chandrasekar MJN. Thiazolidinediones as antidiabetic agents: A critical review. Bioorg Chem 2018; 77:548-567. [PMID: 29475164 DOI: 10.1016/j.bioorg.2018.02.009] [Citation(s) in RCA: 188] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 02/01/2018] [Accepted: 02/10/2018] [Indexed: 01/07/2023]
Abstract
Thiazolidinediones (TZDs) or Glitazones are an important class of insulin sensitizers used in the treatment of Type 2 diabetes mellitus (T2DM). TZDs were reported for their antidiabetic effect through antihyperglycemic, hypoglycemic and hypolipidemic agents. In time, these drugs were known to act by increasing the transactivation activity of Peroxisome Proliferators Activated Receptors (PPARs). The clinically used TZDs that suffered from several serious side effects and hence withdrawn/updated later, were full agonists of PPAR-γ and potent insulin sensitizers. These drugs were developed at a time when limited data were available on the structure and mechanism of PPARs. In recent years, however, PPAR-α/γ, PPAR-α/δ and PPAR-δ/γ dual agonists, PPAR pan agonists, selective PPAR-γ modulators and partial agonists have been investigated. In addition to these, several non PPAR protein alternatives of TZDs such as FFAR1 agonism, GPR40 agonism and ALR2, PTP1B and α-glucosidase inhibition have been investigated to address the problems associated with the TZDs. Using these rationalized approaches, several investigations have been carried out in recent years to develop newer TZDs devoid of side effects. This report critically reviews TZDs, their history, chemistry, mechanism mediated through PPAR, recent advances and future prospects.
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Affiliation(s)
- M J Nanjan
- TIFAC CORE, JSS College of Pharmacy, Ootacamund 643001, Tamil Nadu, India; JSS Academy of Higher Education and Research (Deemed to be University), Mysuru 570015, Karnataka, India
| | - Manal Mohammed
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, Ootacamund 643001, Tamil Nadu, India; JSS Academy of Higher Education and Research (Deemed to be University), Mysuru 570015, Karnataka, India
| | - B R Prashantha Kumar
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, Mysuru 570015, Karnataka, India; JSS Academy of Higher Education and Research (Deemed to be University), Mysuru 570015, Karnataka, India
| | - M J N Chandrasekar
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, Ootacamund 643001, Tamil Nadu, India; JSS Academy of Higher Education and Research (Deemed to be University), Mysuru 570015, Karnataka, India.
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Kaminskyy D, Kryshchyshyn A, Lesyk R. 5-Ene-4-thiazolidinones - An efficient tool in medicinal chemistry. Eur J Med Chem 2017; 140:542-594. [PMID: 28987611 PMCID: PMC7111298 DOI: 10.1016/j.ejmech.2017.09.031] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 07/14/2017] [Accepted: 09/17/2017] [Indexed: 02/02/2023]
Abstract
The presented review is an attempt to summarize a huge volume of data on 5-ene-4-thiazolidinones being a widely studied class of small molecules used in modern organic and medicinal chemistry. The manuscript covers approaches to the synthesis of 5-ene-4-thiazolidinone derivatives: modification of the C5 position of the basic core; synthesis of the target compounds in the one-pot or multistage reactions or transformation of other related heterocycles. The most prominent pharmacological profiles of 5-ene derivatives of different 4-thiazolidinone subtypes belonging to hit-, lead-compounds, drug-candidates and drugs as well as the most studied targets have been discussed. Currently target compounds (especially 5-en-rhodanines) are assigned as frequent hitters or pan-assay interference compounds (PAINS) within high-throughput screening campaigns. Nevertheless, the crucial impact of the presence/nature of C5 substituent (namely 5-ene) on the pharmacological effects of 5-ene-4-thiazolidinones was confirmed by the numerous listed findings from the original articles. The main directions for active 5-ene-4-thiazolidinones optimization have been shown: i) complication of the fragment in the C5 position; ii) introduction of the substituents in the N3 position (especially fragments with carboxylic group or its derivatives); iii) annealing in complex heterocyclic systems; iv) combination with other pharmacologically attractive fragments within hybrid pharmacophore approach. Moreover, the utilization of 5-ene-4-thiazolidinones in the synthesis of complex compounds with potent pharmacological application is described. The chemical transformations cover mainly the reactions which involve the exocyclic double bond in C5 position of the main core and correspond to the abovementioned direction of the 5-ene-4-thiazolidinone modification.
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Affiliation(s)
- Danylo Kaminskyy
- Department of Pharmaceutical, Organic and Bioorganic Chemistry, Danylo Halytsky Lviv National Medical University, Pekarska 69, Lviv-10, 79010, Ukraine
| | - Anna Kryshchyshyn
- Department of Pharmaceutical, Organic and Bioorganic Chemistry, Danylo Halytsky Lviv National Medical University, Pekarska 69, Lviv-10, 79010, Ukraine
| | - Roman Lesyk
- Department of Pharmaceutical, Organic and Bioorganic Chemistry, Danylo Halytsky Lviv National Medical University, Pekarska 69, Lviv-10, 79010, Ukraine.
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Tang XL, Wang CN, Zhu XY, Ni X. Protein tyrosine phosphatase SHP-1 modulates osteoblast differentiation through direct association with and dephosphorylation of GSK3β. Mol Cell Endocrinol 2017; 439:203-212. [PMID: 27614023 DOI: 10.1016/j.mce.2016.08.048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 08/04/2016] [Accepted: 08/16/2016] [Indexed: 12/21/2022]
Abstract
SHP-1, the Src homology-2 (SH2) domain-containing phosphatase 1, is a cytosolic protein-tyrosine phosphatase (PTP) predominantly expressed in hematopoietic-derived cells. Previous studies have focused on the involvement of SHP-1 in osteoclastogenesis. Using primary cultured mouse fetal calvaria-derived osteoblasts as a model, this study aims to investigate the effects of SHP-1 on differentiation and mineralization of osteoblasts and elucidate the signaling pathways responsible for these effects. We found that osteoblasts treated by osteogenic media showed significant increase in SHP-1 expression, which contributed to osteoblastic differentiation and mineralization. Using immunoprecipitation assay, we found that a direct association between SHP-1 and glycogen synthase kinase (GSK)-3β could be detected in differentiated osteoblasts and was significantly inhibited by SHP-1 inhibitor NSC87877. Inhibition of SHP-1 activated GSK3β, thereby leading to suppression of osteoblast differentiation and mineralization, which could be rescued by the inhibitor of GSK3β. In addition, we found that rosiglitazone (RSG) treatment led to significant decrease in SHP-1 expression. Overexpression of SHP-1 reversed RSG-induced GSK3β activation, thus rescuing the inhibitory effect of RSG on osteoblast differentiation and mineralization. These findings suggest that protein tyrosine phosphatase SHP-1 may act as a positive regulator of osteoblast differentiation through direct association with and dephosphorylation of GSK3β. Downregulation of SHP-1 may contribute to RSG-induced inhibition of mouse calvaria osteoblast differentiation by activating GSK3β-dependent pathway.
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Affiliation(s)
- Xiao-Lu Tang
- Department of Physiology and the Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, 200433, China
| | - Chang-Nan Wang
- Department of Physiology and the Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, 200433, China
| | - Xiao-Yan Zhu
- Department of Physiology and the Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, 200433, China.
| | - Xin Ni
- Department of Physiology and the Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, 200433, China.
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Ahad A, Al-Saleh AA, Akhtar N, Al-Mohizea AM, Al-Jenoobi FI. Transdermal delivery of antidiabetic drugs: formulation and delivery strategies. Drug Discov Today 2015; 20:1217-27. [DOI: 10.1016/j.drudis.2015.06.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 05/17/2015] [Accepted: 06/10/2015] [Indexed: 10/23/2022]
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12
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Tang XL, Wang CN, Zhu XY, Ni X. Rosiglitazone inhibition of calvaria-derived osteoblast differentiation is through both of PPARγ and GPR40 and GSK3β-dependent pathway. Mol Cell Endocrinol 2015; 413:78-89. [PMID: 26116229 DOI: 10.1016/j.mce.2015.06.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 05/20/2015] [Accepted: 06/10/2015] [Indexed: 01/17/2023]
Abstract
Rosiglitazone (RSG) can cause bone loss, however the mechanisms remain largely unknown. This study aims to investigate the effects of RSG on differentiation and mineralization of osteoblasts using primary cultured mouse fetal calvaria-derived osteoblasts as a model, and elucidate the receptor and signaling pathways responsible for these effects. We found that RSG suppressed the differentiation and mineralization of calvaria-derived osteoblasts. Peroxisome proliferators-activated receptor γ (PPARγ) siRNA significantly reversed the inhibitory effect of RSG on osteogenic differentiation. The expression of G protein-coupled receptor (GPR) 40 was suppressed during differentiation, but was increased by RSG treatment. GPR40 siRNA significantly reversed the inhibitory effect of RSG on osteogenesis. RSG activated glycogen synthase kinase (GSK)-3β, which in turn decreased β-catenin expression. RSG-induced GSK3β activation was mediated through both PPARγ and GPR40. These results suggest that both PPARγ and GRP40 are required for RSG-induced inhibition of mouse calvaria osteoblast differentiation, which is mediated through GSK3β-dependent pathway.
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Affiliation(s)
- Xiao-Lu Tang
- Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China
| | - Chang-Nan Wang
- Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China
| | - Xiao-Yan Zhu
- Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China.
| | - Xin Ni
- Department of Physiology and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai 200433, China.
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Prasad PS, Imam SS, Aqil M, Sultana Y, Ali A. QbD-based carbopol transgel formulation: characterization, pharmacokinetic assessment and therapeutic efficacy in diabetes. Drug Deliv 2014; 23:1057-66. [PMID: 25033041 DOI: 10.3109/10717544.2014.936536] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In order to develop transdermal drug delivery system that facilitates the skin permeation of Pioglitazone (PZ) encapsulated in carbopol-based transgel system (proniosomes/niosome). The developed formulations were optimized using quality by design (QbD) approach and particle size, percentage entrapment and transdermal flux were determined. It was found to be more efficient delivery carriers with high encapsulation and enhanced flux value demonstrated that the permeation of PZ through skin was significantly increased with developed formulation. The transdermal enhancement from proniosome was 3.16 times higher than that of PZ from control formulation (ethanol buffer formulation, 3:7), which was further confirmed by confocal laser scanning microscopy. In vivo pharmacokinetic study of carbopol transgel showed a significant increase in bioavailability (2.26 times) compared with tablet formulation. It also showed better antidiabetic activity in comparison to marketed tablet, so our results suggest that carbopol-based transgel are an efficient carrier for delivery of pioglitazone through skin.
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Affiliation(s)
- Prem Sundar Prasad
- a Department of Pharmaceutics, Faculty of Pharmacy , Hamdard University , New Delhi , India
| | - Syed Sarim Imam
- a Department of Pharmaceutics, Faculty of Pharmacy , Hamdard University , New Delhi , India
| | - Mohammed Aqil
- a Department of Pharmaceutics, Faculty of Pharmacy , Hamdard University , New Delhi , India
| | - Yasmin Sultana
- a Department of Pharmaceutics, Faculty of Pharmacy , Hamdard University , New Delhi , India
| | - Asgar Ali
- a Department of Pharmaceutics, Faculty of Pharmacy , Hamdard University , New Delhi , India
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Zhao D, Shi Z, Warriner AH, Qiao P, Hong H, Wang Y, Feng X. Molecular mechanism of thiazolidinedione-mediated inhibitory effects on osteoclastogenesis. PLoS One 2014; 9:e102706. [PMID: 25032991 PMCID: PMC4102552 DOI: 10.1371/journal.pone.0102706] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 06/23/2014] [Indexed: 11/19/2022] Open
Abstract
Thiazolidinediones are synthetic peroxisome proliferator-activated receptor γ agonists used to treat type 2 diabetes mellitus. Clinical evidence indicates that thiazolidinediones increase fracture risks in type 2 diabetes mellitus patients, but the mechanism by which thiazolidinediones augment fracture risks is not fully understood. Several groups recently demonstrated that thiazolidinediones stimulate osteoclast formation, thus proposing that thiazolidinediones induce bone loss in part by prompting osteoclastogenesis. However, numerous other studies showed that thiazolidinediones inhibit osteoclast formation. Moreover, the molecular mechanism by which thiazolidinediones modulate osteoclastogenesis is not fully understood. Here we independently address the role of thiazolidinediones in osteoclastogenesis in vitro and furthermore investigate the molecular mechanism underlying the in vitro effects of thiazolidinediones on osteoclastogenesis. Our in vitro data indicate that thiazolidinediones dose-dependently inhibit osteoclastogenesis from bone marrow macrophages, but the inhibitory effect is considerably reduced when bone marrow macrophages are pretreated with RANKL. In vitro mechanistic studies reveal that thiazolidinediones inhibit osteoclastogenesis not by impairing RANKL-induced activation of the NF-κB, JNK, p38 and ERK pathways in bone marrow macrophages. Nonetheless, thiazolidinediones inhibit osteoclastogenesis by suppressing RANKL-induced expression of NFATc1 and c-Fos, two key transcriptional regulators of osteoclastogenesis, in bone marrow macrophages. In addition, thiazolidinediones inhibit the RANKL-induced expression of osteoclast genes encoding matrix metalloproteinase 9, cathepsin K, tartrate-resistant acid phosphatase and carbonic anhydrase II in bone marrow macrophages. However, the ability of thiazolidinediones to inhibit the expression of NFATc1, c-Fos and the four osteoclast genes is notably weakened in RANKL-pretreated bone marrow macrophages. These in vitro studies have not only independently demonstrated that thiazolidinediones exert inhibitory effects on osteoclastogenesis but have also revealed crucial new insights into the molecular mechanism by which thiazolidinediones inhibit osteoclastogenesis.
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Affiliation(s)
- Dongfeng Zhao
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People’s Republic of China
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Zhenqi Shi
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Amy H. Warriner
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Ping Qiao
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Huixian Hong
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Yongjun Wang
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People’s Republic of China
- * E-mail: (YW); (XF)
| | - Xu Feng
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail: (YW); (XF)
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Martin SD, Morrison S, Konstantopoulos N, McGee SL. Mitochondrial dysfunction has divergent, cell type-dependent effects on insulin action. Mol Metab 2014; 3:408-18. [PMID: 24944900 PMCID: PMC4060359 DOI: 10.1016/j.molmet.2014.02.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 02/14/2014] [Accepted: 02/18/2014] [Indexed: 12/25/2022] Open
Abstract
The contribution of mitochondrial dysfunction to insulin resistance is a contentious issue in metabolic research. Recent evidence implicates mitochondrial dysfunction as contributing to multiple forms of insulin resistance. However, some models of mitochondrial dysfunction fail to induce insulin resistance, suggesting greater complexity describes mitochondrial regulation of insulin action. We report that mitochondrial dysfunction is not necessary for cellular models of insulin resistance. However, impairment of mitochondrial function is sufficient for insulin resistance in a cell type-dependent manner, with impaired mitochondrial function inducing insulin resistance in adipocytes, but having no effect, or insulin sensitising effects in hepatocytes. The mechanism of mitochondrial impairment was important in determining the impact on insulin action, but was independent of mitochondrial ROS production. These data can account for opposing findings on this issue and highlight the complexity of mitochondrial regulation of cell type-specific insulin action, which is not described by current reductionist paradigms.
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Key Words
- AMPK, AMP-activated protein kinase
- AS160, Akt substrate of 160 kDa
- Adipocyte
- BSA, bovine serum albumin
- ECAR, extracellular acidification rate
- FoxO1, forkhead box protein O1
- G.O., glucose oxidase
- GLUT4, facilitative glucose transporter isoform 4
- GP, glucose production
- HI-FBS, heat-inactivated foetal bovine serum
- Hepatocyte
- IRS1, insulin receptor substrate 1
- Insulin action
- LDH, lactate dehydrogenase
- MMP, mitochondrial membrane potential
- Mitochondria
- MnTBAP, manganese (III) tetrakis (4-benzoic acid) porphyrin chloride
- PI3K, phosphatidylinositol 3-kinase
- ROS, reactive oxygen species
- Reactive oxygen species
- SOD, superoxide dismutase
- T2D, type 2 diabetes
- TNFα, tumour necrosis factor alpha
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Affiliation(s)
- Sheree D Martin
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Shona Morrison
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Nicky Konstantopoulos
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Sean L McGee
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia ; Cell Signalling and Metabolism Division, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
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16
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Dietary stimulators of the PGC-1 superfamily and mitochondrial biosynthesis in skeletal muscle. A mini-review. J Physiol Biochem 2013; 70:271-84. [DOI: 10.1007/s13105-013-0301-4] [Citation(s) in RCA: 260] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 11/21/2013] [Indexed: 11/26/2022]
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Agyemang K, Han L, Liu E, Zhang Y, Wang T, Gao X. Recent Advances in Astragalus membranaceus Anti-Diabetic Research: Pharmacological Effects of Its Phytochemical Constituents. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2013; 2013:654643. [PMID: 24348714 PMCID: PMC3855992 DOI: 10.1155/2013/654643] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 11/04/2013] [Accepted: 11/05/2013] [Indexed: 12/17/2022]
Abstract
The disease burden of diabetes mellitus is increasing throughout the world. The need for more potent drugs to complement the present anti-diabetic drugs has become an imperative. Astragalus membranaceus, a key component of most Chinese herbal anti-diabetic formulas, has been an important prospect for lead anti-diabetic compounds. It has been progressively studied for its anti-diabetic properties. Ethnopharmacological studies have established its potential to alleviate diabetes mellitus. Recent studies have sought to relate its chemical constituents to types 1 and 2 diabetes mellitus. Its total polysaccharides, saponins, and flavonoids fractions and several isolated compounds have been the most studied. The total polysaccharides fraction demonstrated activity to both types 1 and 2 diabetes mellitus. This paper discusses the anti-diabetic effects and pharmacological action of the chemical constituents in relation to types 1 and 2 diabetes mellitus.
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Affiliation(s)
- Kojo Agyemang
- Tianjin State Key Laboratory of Modern Chinese Medicine, 312 Anshanxi Road, Nankai District, Tianjin 300193, China
- Noguchi Memorial Institute for Medical Research, P.O. Box LG 581, Legon, Accra, Ghana
| | - Lifeng Han
- Tianjin State Key Laboratory of Modern Chinese Medicine, 312 Anshanxi Road, Nankai District, Tianjin 300193, China
| | - Erwei Liu
- Tianjin State Key Laboratory of Modern Chinese Medicine, 312 Anshanxi Road, Nankai District, Tianjin 300193, China
| | - Yi Zhang
- Tianjin State Key Laboratory of Modern Chinese Medicine, 312 Anshanxi Road, Nankai District, Tianjin 300193, China
| | - Tao Wang
- Tianjin State Key Laboratory of Modern Chinese Medicine, 312 Anshanxi Road, Nankai District, Tianjin 300193, China
| | - Xiumei Gao
- Tianjin State Key Laboratory of Modern Chinese Medicine, 312 Anshanxi Road, Nankai District, Tianjin 300193, China
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18
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Atamanyuk D, Zimenkovsky B, Atamanyuk V, Lesyk R. 5-Ethoxymethylidene-4-thioxo-2-thiazolidinone as Versatile Building Block for Novel Biorelevant Small Molecules with Thiopyrano[2,3-d][1,3]thiazole Core. SYNTHETIC COMMUN 2013. [DOI: 10.1080/00397911.2013.800552] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Dmytro Atamanyuk
- a Department of Pharmaceutical, Organic, and Bioorganic Chemistry , Danylo Halytsky Lviv National Medical University , Lviv , Ukraine
| | - Borys Zimenkovsky
- a Department of Pharmaceutical, Organic, and Bioorganic Chemistry , Danylo Halytsky Lviv National Medical University , Lviv , Ukraine
| | - Vasyl Atamanyuk
- a Department of Pharmaceutical, Organic, and Bioorganic Chemistry , Danylo Halytsky Lviv National Medical University , Lviv , Ukraine
| | - Roman Lesyk
- a Department of Pharmaceutical, Organic, and Bioorganic Chemistry , Danylo Halytsky Lviv National Medical University , Lviv , Ukraine
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Pandit V, Gorantla R, Devi K, Pai R, Sarasija S. Preparation and characterization of pioglitazone cyclodextrin inclusion complexes. J Young Pharm 2013; 3:267-74. [PMID: 22224032 PMCID: PMC3249738 DOI: 10.4103/0975-1483.90234] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Pioglitazone, a class II Biopharmaceutical Classification System drug having poor water solubility and slow dissolution rate may have a negative impact on its subtherapeutic plasma drug levels leading to therapeutic failure. In order to improve its water solubility and thus dissolution, cyclodextrin complexation technique was followed. The phase solubility studies were carried using three different types of cyclodextrins viz., β, methyl-β and γ-cyclodextrins. The Gibbs free energy was calculated in order to determine ease of the complexation. Binary systems of pioglitazone with cyclodextrins were prepared by kneading method and spray drying method. The phase solubility profiles with all the three cyclodextrins were classified as AL-type, indicating the formation of 1:1 stoichiometric inclusion complexes. The complexation capability of cyclodextrins with pioglitazone increased in the order of methyl-β > β > γ-cyclodextrin. The Gibbs free energy was found to be in the order γ > methyl-β > β cyclodextrin. Characterization of inclusion complexes was done by solubility studies, in vitro dissolution studies, Fourier transformation-infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and X-ray powder diffractometry studies. Inclusion complexes exhibited higher rates of dissolution than the corresponding physical mixtures and pure drug. Greater solubility was observed with spray-dried methyl-β cyclodextrin complexes (2.29 ± 0.001 mg/ml) in comparison to the kneaded methyl-β cyclodextrin complexes (1.584 ± 0.053 mg/ml) and pure drug (0.0714 ± 0.0018 mg/ml).
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Affiliation(s)
- V Pandit
- Department of Pharmaceutics, Al Ameen College of Pharmacy, Bangalore, India
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20
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de Albuquerque Couto J, Saraiva KLA, Barros CD, Udrisar DP, Peixoto CA, Vieira JSBC, do Carmo Alves de Lima M, Galdino SL, da Rocha Pitta I, Wanderley MI. Effect of chronic treatment with new benzylidene-thiazolidine-2,4-dione (LPSF/GQ-06) with potential hypoglycemic on rat Leydig cell steroidogenesis. Med Chem Res 2013. [DOI: 10.1007/s00044-012-0024-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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21
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El-Bassossy HM, Abo-Warda SM, Fahmy A. Rosiglitazone, a peroxisome proliferator-activated receptor γ stimulant, abrogates diabetes-evoked hypertension by rectifying abnormalities in vascular reactivity. Clin Exp Pharmacol Physiol 2012; 39:643-9. [DOI: 10.1111/j.1440-1681.2012.05724.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
| | - Shaymaa M Abo-Warda
- Department of Pharmacology; Faculty of Pharmacy; Zagazig University; Zagazig; Egypt
| | - Ahmed Fahmy
- Department of Pharmacology; Faculty of Pharmacy; Zagazig University; Zagazig; Egypt
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22
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Pandit V, Pai RS, Devi K, Suresh S. In vitro-in vivo evaluation of fast-dissolving tablets containing solid dispersion of pioglitazone hydrochloride. J Adv Pharm Technol Res 2012; 3:160-70. [PMID: 23057002 PMCID: PMC3459445 DOI: 10.4103/2231-4040.101008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Investigation of in vitro/in vivo behavior of fast-dissolving tablets containing solid dispersions of pioglitazone hydrochloride (PIO) is the focus of the present research work. The effect of various hydrophilic polymers on the aqueous solubility of PIO was studied. Poly vinyl pyrrolidine K 30 (PVPK 30) carrier was selected and solid dispersions were prepared by various methods. Evaluation of solid dispersion for percentage yield, drug content, solubility, and Fourier Transform Infrared-indicated kneading method was most appropriate. Furthermore, the dissolution studies exhibited an enhancement in drug dissolution. One-way ANOVA of in vitro data suggested that there was significant (P ≤ 0.05) difference in dissolution profile of PIO solid dispersion when compared with pure drug and commercial product. Infrared spectroscopy, differential scanning calorimetry, and powder X-ray diffraction performed on solid dispersion indicated lack of physicochemical interaction between the drug and the carrier. The selected formulation is compressed into fast-dissolving tablets which were further evaluated for tablet properties and in vitro drug release. In vivo studies of pure drug, selected formulation, and marketed product were carried out in male Wistar rats and pharmacokinetic parameters were calculated using Kinetica software 2000. The best formulation has shown T(max) of 1 hour which was highly significant (P < 0.01) when compared with pure drug and marketed formulation. Therefore, the solid dispersions prepared by kneading method using PVPK 30 as hydrophilic carrier can be successfully used for improvement of dissolution of PIO and resulted in faster onset of action as indicated by in vivo studies.
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Affiliation(s)
- Vinay Pandit
- Department of Pharmaceutics, Faculty of Pharmacy, Al-Ameen College of Pharmacy, Bangalore 560027, Karnataka, India
| | - Roopa S. Pai
- Department of Pharmaceutics, Faculty of Pharmacy, Al-Ameen College of Pharmacy, Bangalore 560027, Karnataka, India
| | - Kusum Devi
- Department of Continuing Education and Quality Improvement, Faculty of Pharmacy, Al-Ameen College of Pharmacy, Bangalore 560027, Karnataka, India
| | - Sarasija Suresh
- Department of Pharmaceutical Technology (Formulations), NIPER, Mohali, Punjab, India
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23
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Burris TP, Busby SA, Griffin PR. Targeting orphan nuclear receptors for treatment of metabolic diseases and autoimmunity. ACTA ACUST UNITED AC 2012; 19:51-9. [PMID: 22284354 DOI: 10.1016/j.chembiol.2011.12.011] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 12/13/2011] [Accepted: 12/14/2011] [Indexed: 02/08/2023]
Abstract
The nuclear receptor (NR) superfamily is composed of 48 members in humans and includes receptors for steroid hormones, thyroid hormone, various lipids and oxysterols. This superfamily has been a rich source of drug targets for myriad diseases including inflammation, cancer, and metabolic disorders. Approximately half of the superfamily have well characterized natural ligands whereas the remaining receptors are considered orphan receptors and remain a focus of a number of investigators assessing their ability to be regulated by ligands. Here, we review recent discoveries that yield important insight into the druggability of three orphan nuclear receptors: the retinoic acid receptor-like orphan receptors (RORs), peroxisome proliferator-activated receptor γ (PPARγ), and liver receptor homolog-1 (LRH-1).
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Affiliation(s)
- Thomas P Burris
- Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, FL 33458, USA.
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24
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Lee OH, Seo DH, Park CS, Kim YC. Puerarin enhances adipocyte differentiation, adiponectin expression, and antioxidant response in 3T3-L1 cells. Biofactors 2010; 36:459-67. [PMID: 20806284 DOI: 10.1002/biof.119] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Accepted: 07/10/2010] [Indexed: 01/14/2023]
Abstract
Puerarin, a major isoflavone glycoside from Kudzu root (Pueraria lobata), has been reported to exert antihyperglycemic and antioxidant effects and thus have pharmacological actions in the treatment of diabetes and cardiovascular diseases. We investigated the effects of puerarin on the changes of key gene expression associated with adipocyte differentiation and insulin sensitivity and link to cellular antioxidant response pathways. Puerarin treatment significantly enhanced differentiation of 3T3-L1 preadipocytes accompanying increased lipid accumulation and glucose-6-phosphate dehydrogenase (G6PDH) activity. At a molecular level, puerarin upregulated mRNA expression of peroxisome proliferator-activated receptor γ (PPARγ) and its target genes, an adipocyte-specific fatty acid binding protein (aP2) and GLUT4. Puerarin also caused a significant increase in mRNA level of adiponectin, an important insulin-sensitizing adipocytokine that is downregulated in insulin-resistant and diabetic states. In addition, treatment with puerarin was found to upregulate mRNA levels of G6PDH, glutathione reductase, and catalase, all of which are important for endogenous antioxidant responses. These data suggest that the hypoglycemic effects of puerarin can be attributed to the upregulation of PPARγ and its downstream target genes, GLUT4 and adiponectin expression, leading to increased glucose utilization. Puerarin may also be effective in preventing the rise of oxidative stress during adipocyte differentiation by increasing endogenous antioxidant responses.
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Affiliation(s)
- Ok-Hwan Lee
- Department of Nutrition, University of Massachusetts, Amherst, MA 01003, USA
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25
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Polovkovych SV, Karkhut AI, Marintsova NG, Novikov VP. Synthesis of new 5-acetyl(arylmethyliden)-4-thiazolidones. HETEROATOM CHEMISTRY 2010. [DOI: 10.1002/hc.20631] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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26
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Abstract
Insulin resistance is a major risk factor for developing type 2 diabetes caused by the inability of insulin-target tissues to respond properly to insulin, and contributes to the morbidity of obesity. Insulin action involves a series of signaling cascades initiated by insulin binding to its receptor, eliciting receptor autophosphorylation and activation of the receptor tyrosine kinase, resulting in tyrosine phosphorylation of insulin receptor substrates (IRSs). Phosphorylation of IRSs leads to activation of phosphatidylinositol 3-kinase (PI3K) and, subsequently, to activation of Akt and its downstream mediator AS160, all of which are important steps for stimulating glucose transport induced by insulin. Although the mechanisms underlying insulin resistance are not completely understood in skeletal muscle, it is thought to result, at least in part, from impaired insulin-dependent PI3K activation and downstream signaling. This review focuses on the molecular basis of skeletal muscle insulin resistance in obesity and type 2 diabetes. In addition, the effects of insulin-sensitizing agent treatment and lifestyle intervention of human insulin-resistant subjects on insulin signaling cascade are discussed. Furthermore, the role of Rho-kinase, a newly identified regulator of insulin action in insulin control of metabolism, is addressed.
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Affiliation(s)
- Kangduk Choi
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA
| | - Young-Bum Kim
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA
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27
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Xu J, Stanislaus S, Chinookoswong N, Lau YY, Hager T, Patel J, Ge H, Weiszmann J, Lu SC, Graham M, Busby J, Hecht R, Li YS, Li Y, Lindberg R, Véniant MM. Acute glucose-lowering and insulin-sensitizing action of FGF21 in insulin-resistant mouse models--association with liver and adipose tissue effects. Am J Physiol Endocrinol Metab 2009; 297:E1105-14. [PMID: 19706786 DOI: 10.1152/ajpendo.00348.2009] [Citation(s) in RCA: 269] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Recombinant fibroblast growth factor (FGF)21 has antihyperglycemic, antihyperlipidemic, and antiobesity effects in diabetic rodent and monkey models. Previous studies were confined to measuring steady-state effects of FGF21 following subchronic or chronic administration. The present study focuses on the kinetics of biological actions of FGF21 following a single injection and on the associated physiological and cellular mechanisms underlying FGF21 actions. We show that FGF21 resulted in rapid decline of blood glucose levels and immediate improvement of glucose tolerance and insulin sensitivity in two animal models of insulin resistance (ob/ob and DIO mice). In ob/ob mice, FGF21 led to a 40-60% decrease in blood glucose, insulin, and amylin levels within 1 h after injection, and the maximal effects were sustained for more than 6 h despite the 1- to 2-h half-life of FGF21. In DIO mice, FGF21 reduced fasting blood glucose and insulin levels and improved glucose tolerance and insulin sensitivity within 3 h of treatment. The acute improvement of glucose metabolism was associated with a 30% reduction of hepatic glucose production and an increase in peripheral glucose turnover. FGF21 appeared to have no direct effect on ex vivo pancreatic islet insulin or glucagon secretion. However, it rapidly induced typical FGF signaling in liver and adipose tissues and in several hepatoma-derived cell lines and differentiated adipocytes. FGF21 was able to inhibit glucose release from H4IIE hepatoma cells and stimulate glucose uptake in 3T3-L1 adipocytes. We conclude that the acute glucose-lowering and insulin-sensitizing effects of FGF21 are potentially associated with its metabolic actions in liver and adipose tissues.
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Affiliation(s)
- Jing Xu
- Amgen Inc., MS 29-1-A, One Amgen Center Dr., Thousand Oaks, CA 91320, USA.
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28
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PPAR activators and COX inhibitors selectively block cytokine-induced COX-2 expression and activity in human aortic smooth muscle cells. Eur J Pharmacol 2009; 606:121-9. [PMID: 19374865 DOI: 10.1016/j.ejphar.2009.01.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 12/16/2008] [Accepted: 01/09/2009] [Indexed: 11/22/2022]
Abstract
Atherosclerotic complications are related to the unstable character of the plaque rather than its volume. Vulnerable plaques often contain a large lipid core, a reduced content of smooth muscle cells (SMCs), and an accumulation of inflammatory cells. Regulation of this inflammatory response is an essential element in chronic inflammatory diseases such as atherosclerosis. Nuclear receptors and particularly peroxisome proliferator-activated receptors (PPARs) have emerged as therapeutic targets with a widespread impact on the treatment of metabolic disorders because they can modulate gene expression involved in lipid and glucose homeostasis and can exert anti-inflammatory properties. However, little is known about nuclear receptor effects on SMC inflammation, which produces large amounts of IL-6 and prostanoids. The aim of this study was to evaluate anti-inflammatory properties of nuclear receptor activators in a human physiological SMC model. We show that PPAR activators, as well as liver X receptor alpha, farnesoid X receptor and retinoid X receptor alpha activators, inhibit IL-1beta-induced SMC 6-keto PGF1alpha synthesis, an index of cyclooxygenase (COX)-2 activity, with IC(50) between 1 and 69 microM. In contrast, PPARgamma activators, as exemplified by rosiglitazone and pioglitazone, were unable to inhibit cytokine-induced 6-keto PGF1alpha synthesis. We also demonstrate for the first time that the COX-2 inhibitor rofecoxib can reduce 6-keto PGF1alpha production by both enzymatic inhibition and transcriptional repression. These results show that some nuclear receptor activators have SMC anti-inflammatory properties due to COX-2 inhibition which could participate in their anti-atherosclerotic properties beyond lipid impacts.
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Gaborit B, Andreelli F. Mécanismes de l’action antidiabétique des thiazolidinediones. NUTR CLIN METAB 2008. [DOI: 10.1016/j.nupar.2007.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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30
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Gentile MT, Vecchione C, Marino G, Aretini A, Di Pardo A, Antenucci G, Maffei A, Cifelli G, Iorio L, Landolfi A, Frati G, Lembo G. Resistin impairs insulin-evoked vasodilation. Diabetes 2008; 57:577-83. [PMID: 18065520 DOI: 10.2337/db07-0557] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Since vascular dysfunction is a main trait of obese subjects, in the present study we evaluated the vascular impact of resistin, a recently discovered hormone markedly increased in obesity. RESEARCH DESIGN AND METHODS We performed our analysis on aortic and mesenteric segments from young and old C57BL/6 mice and on cultured endothelial cells. Resistin-induced vascular effect was evaluated in vitro and in vivo. Molecular analyses were performed by immunoprecipitation and Western blotting. RESULTS Recombinant murine resistin did not induce changes in either basal vascular tone or phenylephrine-induced vascular contraction. In contrast, both in vivo and in vitro administration of resistin significantly impaired dose-dependent insulin-evoked vasodilation by reducing endothelial nitric oxide synthase (eNOS) enzymatic activity. This effect of resistin was selective for insulin vascular action, since vasodilatation induced by increasing doses of acetylcholine or nitroglycerin was not influenced by the hormone. Molecular analysis of endothelial cells further detailed resistin-induced vascular resistance by showing impairment of insulin-evoked AKT and eNOS phosphorylations after exposure to resistin. Even this latter abnormality is selective of insulin signaling since AKT/eNOS phosphorylations are normally activated during acetylcholine stimulation. More important, the resistin-induced endothelial dysfunction depends on resistin's ability to alter insulin receptor substrate (IRS)-1 tyrosine/serine phosphorylation and its consequent interaction with phosphatidylinositol 3-kinase. CONCLUSIONS Our results demonstrate that resistin is able to induce a selective vascular insulin resistance-impairing endothelial IRS-1 signaling pathway that leads to eNOS activation and vasodilation.
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Voigt JP, Bramlage P, Fink H. Hypophagic effect of the angiotensin AT1 receptor antagonist irbesartan in rats. Eur J Pharmacol 2007; 564:131-7. [PMID: 17408613 DOI: 10.1016/j.ejphar.2007.02.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 02/13/2007] [Accepted: 02/16/2007] [Indexed: 10/23/2022]
Abstract
Recent experimental and clinical studies report beneficial metabolic effects of antihypertensive drugs interfering with angiotensin. Antagonists at the angiotensin AT(1) receptor can reduce blood glucose and triglyceride levels. So far, there is little evidence, however, that angiotensin AT(1) receptor antagonists can also affect food intake. Particularly unknown is if drugs of this class can have acute effects on short term feeding. To address this issue, the angiotensin AT(1) receptor antagonist irbesartan was studied in a one-hour feeding paradigm in rats. In this study, irbesartan was investigated in comparison with fenfluramine, an established satiating drug, and the angiotensin converting enzyme (ACE) inhibitor captopril. We found a significant reduction of one-hour food intake following 100-200 mg/kg (i.p.) irbesartan. The ACE inhibitor captopril (25-100 mg/kg i.p.) remained without effect on food intake and fenfluramine showed the expected hypophagic action starting at 1 mg/kg (i.p.). The hypophagic effect of irbesartan could not be attributed to sedation or any gross effect on motor activity as determined both upon feeding and independent activity experiments. Fenfluramine (1 mg/kg) and irbesartan (100 mg/kg) did not reduce the latency to feed, but similarly reduced the eating rate at the beginning of the test meal. In conclusion, the present study demonstrates a hypophagic effect of the angiotensin AT(1) receptor antagonist irbesartan that cannot be attributed to sedation or antidipsic effects of the drug.
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Affiliation(s)
- Jörg-Peter Voigt
- Institute of Pharmacology and Toxicology, School of Veterinary Medicine, Freie Universität Berlin, Koserstrasse 20, 14195 Berlin, Germany.
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Germain P, Chambon P, Eichele G, Evans RM, Lazar MA, Leid M, De Lera AR, Lotan R, Mangelsdorf DJ, Gronemeyer H. International Union of Pharmacology. LXIII. Retinoid X receptors. Pharmacol Rev 2007; 58:760-72. [PMID: 17132853 DOI: 10.1124/pr.58.4.7] [Citation(s) in RCA: 376] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The physiological effects of retinoic acids (RAs) are mediated by members of two families of nuclear receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs), which are encoded by three distinct human genes, RXRalpha, RXRbeta, and RXRgamma. RARs bind both all-trans- and 9-cis-RA, whereas only the 9-cis-RA stereoisomer binds to RXRs. As RXR/RAR heterodimers, these receptors control the transcription of RA target genes through binding to RA-response elements. This review is focused on the structure, mode of action, ligands, expression, and pharmacology of RXRs. Given their role as common partners to many other members of the nuclear receptor superfamily, these receptors have been the subject of intense scrutiny. Moreover, and despite numerous studies since their initial discovery, RXRs remain enigmatic nuclear receptors, and there is still no consensus regarding their role. Indeed, multiple questions about the actual biological role of RXRs and the existence of an endogenous ligand have still to be answered.
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Affiliation(s)
- Pierre Germain
- Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, Communauté Urbaine de Strasbourg, France.
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Ko GTC, Tsang PCC, Wai HPS, Kan ECY, Chan HCK. Rosiglitazone versus bedtime insulin in the treatment of patients with conventional oral antidiabetic drug failure: a 1-year randomized clinical trial. Adv Ther 2006; 23:799-808. [PMID: 17142216 DOI: 10.1007/bf02850321] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This study was conducted to evaluate the efficacy and tolerability of rosiglitazone in the treatment of patients with secondary oral antidiabetic drug (OAD) failure and to directly compare its use with bedtime insulin. A total of 112 Chinese patients with type 2 diabetes and conventional OAD failure were recruited. Patients were randomly assigned to treatment with rosiglitazone or bedtime isophane insulin; they continued to take their original oral antidiabetic drugs. Glycemic index, other clinical profiles, and tolerability were assessed during treatment and 1 y after add-on treatment was provided. Among the 112 patients, mean age (+/-SD) was 58.2+/-11.0 y (median, 58 y; range, 37 to 84 y). Both rosiglitazone (n=56) and insulin (n=56) significantly improved fasting glucose (2.4 and 3.7 mmol/L, respectively) and hemoglobin A1c concentrations (1.1% and 1.3%, respectively). Both therapies increased body mass index after 1 y of treatment (0.9 and 0.8 kg/m2, respectively). Only rosiglitazone increased high-density lipoprotein cholesterol concentrations (0.1 mmol/L). Four patients (7.1%) who were given rosiglitazone developed adverse effects (2, ankle edema, and 2, gastrointestinal disturbance). Six insulin-treated patients (10.7%) described adverse effects (5, early morning hypoglycemia, and 1, anxiety). Investigators concluded that in Chinese patients with type 2 diabetes and secondary conventional OAD failure, 1 y of treatment with rosiglitazone or bedtime insulin added to the regular regimen resulted in similar improvements in glycemic control. Rosiglitazone was also associated with improved high-density lipoprotein cholesterol levels. The addition of rosiglitazone may offer a safe and effective alternative to bedtime insulin treatment.
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Affiliation(s)
- Gary T C Ko
- Department of Medicine, AH Nethersole Hospital, Tai Po, Hong Kong, China
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Reifel-Miller A, Otto K, Hawkins E, Barr R, Bensch WR, Bull C, Dana S, Klausing K, Martin JA, Rafaeloff-Phail R, Rafizadeh-Montrose C, Rhodes G, Robey R, Rojo I, Rungta D, Snyder D, Wilbur K, Zhang T, Zink R, Warshawsky A, Brozinick JT. A Peroxisome Proliferator-Activated Receptor α/γ Dual Agonist with a Unique in Vitro Profile and Potent Glucose and Lipid Effects in Rodent Models of Type 2 Diabetes and Dyslipidemia. Mol Endocrinol 2005; 19:1593-605. [PMID: 15831517 DOI: 10.1210/me.2005-0015] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
AbstractLSN862 is a novel peroxisome proliferator-activated receptor (PPAR)α/γ dual agonist with a unique in vitro profile that shows improvements on glucose and lipid levels in rodent models of type 2 diabetes and dyslipidemia. Data from in vitro binding, cotransfection, and cofactor recruitment assays characterize LSN862 as a high-affinity PPARγ partial agonist with relatively less but significant PPARα agonist activity. Using these same assays, rosiglitazone was characterized as a high-affinity PPARγ full agonist with no PPARα activity. When administered to Zucker diabetic fatty rats, LSN862 displayed significant glucose and triglyceride lowering and a significantly greater increase in adiponectin levels compared with rosiglitazone. Expression of genes involved in metabolic pathways in the liver and in two fat depots from compound-treated Zucker diabetic fatty rats was evaluated. Only LSN862 significantly elevated mRNA levels of pyruvate dehydrogenase kinase isozyme 4 and bifunctional enzyme in the liver and lipoprotein lipase in both fat depots. In contrast, both LSN862 and rosiglitazone decreased phosphoenol pyruvate carboxykinase in the liver and increased malic enzyme mRNA levels in the fat. In addition, LSN862 was examined in a second rodent model of type 2 diabetes, db/db mice. In this study, LSN862 demonstrated statistically better antidiabetic efficacy compared with rosiglitazone with an equivalent side effect profile. LSN862, rosiglitazone, and fenofibrate were each evaluated in the humanized apoA1 transgenic mouse. At the highest dose administered, LSN862 and fenofibrate reduced very low-density lipoprotein cholesterol, whereas, rosiglitazone increased very low-density lipoprotein cholesterol. LSN862, fenofibrate, and rosiglitazone produced maximal increases in high-density lipoprotein cholesterol of 65, 54, and 30%, respectively. These findings show that PPARγ full agonist activity is not necessary to achieve potent and efficacious insulin-sensitizing benefits and demonstrate the therapeutic advantages of a PPARα/γ dual agonist.
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MESH Headings
- Adiponectin
- Alkynes/chemistry
- Alkynes/pharmacology
- Animals
- Binding, Competitive
- Body Weight
- Cholesterol/metabolism
- Cholesterol, HDL/metabolism
- Cholesterol, VLDL/metabolism
- Cinnamates/chemistry
- Cinnamates/pharmacology
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Type 2/drug therapy
- Diabetes Mellitus, Type 2/metabolism
- Dose-Response Relationship, Drug
- Fenofibrate/pharmacology
- Gene Expression Regulation, Enzymologic
- Glucose/metabolism
- Homozygote
- Humans
- Hyperlipidemias/drug therapy
- Hyperlipidemias/metabolism
- In Vitro Techniques
- Insulin/metabolism
- Intercellular Signaling Peptides and Proteins/metabolism
- Kinetics
- Lipid Metabolism
- Liver/enzymology
- Male
- Mice
- Mice, Transgenic
- Models, Chemical
- PPAR alpha/agonists
- PPAR alpha/metabolism
- PPAR gamma/agonists
- PPAR gamma/metabolism
- Protein Binding
- Protein Isoforms
- RNA, Messenger/metabolism
- Rats
- Rosiglitazone
- Thiazolidinediones/pharmacology
- Transfection
- Triglycerides/metabolism
- Two-Hybrid System Techniques
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Affiliation(s)
- Anne Reifel-Miller
- Endocrinology Division, Lilly Research Laboratories, Indianapolis, Indiana 46285, USA.
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Li DD, Chen JH, Chen Q, Li GW, Chen J, Yue JM, Chen ML, Wang XP, Shen JH, Shen X, Jiang HL. Swietenia mahagony extract shows agonistic activity to PPAR(gamma) and gives ameliorative effects on diabetic db/db mice. Acta Pharmacol Sin 2005; 26:220-2. [PMID: 15663902 DOI: 10.1111/j.1745-7254.2005.00527.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
AIM To search the peroxisome proliferator-activated receptor g (PPAR(gamma)) agonists from Swietenia mahagony extract (SmE) and observe the possible ameliorative effects of SmE on diabetic db/db mice. METHODS The PPAR(gamma) agonistic activity of SmE was screened by yeast-two hybrid system. The blood glucose levels of diabetic db/db mice were measured using a blood glucose level monitor and the data were statistically analyzed by NDST8.8W software. RESULTS By using the clinical drug rosiglitazone as a positive control, it was found that the PPARg agonistic activity of SmE at a concentration of 50 microg/L was approximately half that of 35.7 microg/L (0.1 micromol/L) of rosiglitazone. At the dose of 1000 mg/kg, SmE remarkably decreased the blood glucose concentration of db/db mice from (15.26+/-2.98) to (7.58+/-2.20) mmol/L, and reduced the blood glucose levels by 55.49% compared with the control group (P<0.01). CONCLUSION SmE shows agonistic activity to PPARg and can ameliorate the blood glucose levels of diabetic db/db mice. SmE may be thus used as a potential agent for diabetes therapy.
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Affiliation(s)
- Dan-Dan Li
- Drug Discovery and Design Center, State Key Lab of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China
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Ialenti A, Grassia G, Di Meglio P, Maffia P, Di Rosa M, Ianaro A. Mechanism of the anti-inflammatory effect of thiazolidinediones: relationship with the glucocorticoid pathway. Mol Pharmacol 2005; 67:1620-8. [PMID: 15684043 DOI: 10.1124/mol.104.004895] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The glucocorticoid receptor (GR) and peroxisome proliferator-activated receptors (PPARs) play important roles in both physiological and pathological conditions such as cell differentiation, lipolysis, control of glucose metabolism, immunity, and inflammation. In fact, recent studies suggest that the thiazolidinedione (TZD) class of PPAR-gamma ligands, like glucocorticoids, may also be clinically beneficial in several inflammatory diseases, even if the molecular mechanisms responsible for these activities have not yet been clarified. In this study, by using a murine model of inflammation, the carrageenin-induced paw edema in mouse, we show that the anti-inflammatory activity exhibited by the PPAR-gamma agonists rosiglitazone and ciglitazone is reversed by the GR antagonist RU486 (17 beta-hydroxy-11 beta-[4-dimethylamino phenyl]-17 alpha-[1-propynyl]estra-4,9-dien-3-one). Moreover, by using a conditional GR null cell line, we demonstrate, for the first time to our knowledge, that one of the possible mechanisms explaining the anti-inflammatory activity of TZDs is their ability to activate GR nuclear translocation. In addition, by using J774 cell line lacking PPAR-gamma, we demonstrate that PPAR-gamma expression could not be essential for TZD-mediated GR nuclear translocation, thus explaining, at least in part, the molecular mechanism underlying their anti-inflammatory activity.
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Affiliation(s)
- Armando Ialenti
- Department of Experimental Pharmacology, University of Naples Federico II, Italy
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Asensio C, Muzzin P, Rohner-Jeanrenaud F. Role of glucocorticoids in the physiopathology of excessive fat deposition and insulin resistance. Int J Obes (Lond) 2004; 28 Suppl 4:S45-52. [PMID: 15592486 DOI: 10.1038/sj.ijo.0802856] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Glucocorticoids are important hormones in the regulation of metabolic homeostasis. We infused normal rats with dexamethasone given intracerebroventricularly (i.c.v.) for 3 days. This resulted in hyperphagia, hyperinsulinemia, and marked insulin resistance. Similar metabolic defects were observed following i.c.v. infusion of neuropeptide Y (NPY) in normal rats. As central dexamethasone infusion enhanced NPY content in the arcuate nucleus, it suggested that its metabolic effects are mediated by NPY. Moreover, due to the lack of effects observed in vagotomized animals, activation of the parasympathetic nervous system by central dexamethasone infusion is proposed. Glucocorticoid action is known to involve prereceptor metabolism by enzymes such as 11beta-HSD-1 that converts inactive into active glucocorticoids. Mice overexpressing 11beta-HSD-1 in adipose tissue were shown to be obese and insulin resistant. We recently observed that adipose tissue 11beta-HSD-1 mRNA expression is increased at the onset of high-fat diet-induced obesity and positively correlated with the degree of hyperglycemia. In human obesity, increased adipose tissue 11beta-HSD-1 expression and activity were also reported. Resistin is a new adipose tissue-secreted hormone shown to play a role in glucose homeostasis by increasing hepatic glucose production and inhibiting muscle and adipose tissue glucose utilization. We observed increased adipose tissue resistin expression in the early phase of high-fat diet-induced obesity as well as decreased resistin expression in response to leptin. A positive correlation between glycemia and adipose tissue resistin expression further suggested a role of this hormone in the development of insulin resistance. The melanocortin system is another important player in the regulation of energy balance. Peripheral administration of a melanocortin agonist decreased food intake and body weight and favored lipid oxidation, effects that were more marked in obese than in lean rats. It is proposed that both resistin and melanocortin agonists may influence adipose tissue 11beta-HSD-1, thereby decreasing or enhancing glucose metabolism.
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Affiliation(s)
- C Asensio
- Laboratory of Metabolism, Department of Internal Medicine, Department of Cell Biology and Metabolism, Faculty of Medicine, University of Geneva, Switzerland
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Abstract
SUPPLEMENTARY ORAL ANTIDIABETICS: Thiazolidinediones or glitazones are a new class of oral antidiabetics, the effects on blood sugar control of which are mediated by the sensitivity of the peripheral tissue to the effect of insulin. Hence, their effect is complementary to that of the insulin secreting agents and that of metformin, which acts by blocking the hepatic production of glucose. OTHER BENEFICIAL EFFECTS: Other than their effect on blood glucose, thiazolidinediones have a favorable influence upon the cardiovascular risk factors or markers such as blood pressure, C-reactive protein and metalloproteinase-9. They also appear to induce long term preservation of the beta-cell capital. Principle side effects are salt-water retention with a risk of decompensation of a pre-existing heart failure and weight gain with regard to the subcutaneous adipose tissue, without deleterious effects on blood glucose control.
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Affiliation(s)
- Jean-Frédéric Blicklé
- Service de médecine interne, diabète et maladies métaboliques, Hôpitaux universitaires de Strasbourg.
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Hyun K, Lee D, Lee BS, Kim C. Receptor-based 3D QSAR Studies on PPAR? Agonists using CoMFA and CoMSIA Approaches. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/qsar.200430878] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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Rival Y, Stennevin A, Puech L, Rouquette A, Cathala C, Lestienne F, Dupont-Passelaigue E, Patoiseau JF, Wurch T, Junquéro D. Human adipocyte fatty acid-binding protein (aP2) gene promoter-driven reporter assay discriminates nonlipogenic peroxisome proliferator-activated receptor gamma ligands. J Pharmacol Exp Ther 2004; 311:467-75. [PMID: 15273253 DOI: 10.1124/jpet.104.068254] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) regulate storage and catabolism of fats and carbohydrates. PPARgamma activity increases insulin sensitivity and adipocyte differentiation at the expense of adipogenesis and weight gain. The goal of this study was to 1) clone the promoter of the human adipocyte fatty acid binding protein (aP2) gene, namely fatty acid-binding protein-4, 2) characterize its pharmacological regulation, and 3) determine its putative predictability for adipogenesis. Among the selected PPAR agonists, rosiglitazone and pioglitazone displayed the highest maximal efficacy (E(max)) on reporter-gene assays in COS-7 cells cotransfected by either a galactosidase 4-response element-based or a human aP2 promoter-based Luc reporter vector, along with either chimeric or full-length human PPAR expression plasmids. The non-subtype-selective 2-(4-[2-(3-[2,4-difluorophenyl]-1-heptylureido)ethyl]phenoxy)-2-methyl-butyric acid (GW-2331) and the compounds [4-[3-(4-acetyl-3-hydroxy-2-propylphenoxy)-propoxyl]phenoxy]-acetic acid (L-165041), (4-((2S,5S)-5-(2-(bis(phenylmethyl)amino)-2-oxoethyl)-2-heptyl-4-oxo-3-thiazolidinyl)butyl)-benzoic acid (GW-0072), and indomethacin behaved as partial agonists relative to pioglitazone in full-length human aP2-PPARgamma2. Beyond their partial PPARgamma agonist properties, these compounds elicited a lower maximal up-regulation of mouse aP2 mRNA in 3T3-L1 adipocytes as compared with pioglitazone; these properties paralleled a time-dependent increase in neutral lipids. By contrast, the selective PPARalpha agonist 2,2-dichloro-12-(4-chlorophenyl)dodecanoic acid (BM-17.0744) neither stimulated the human aP2-PPARalpha promoter reporter-gene assay, thus demonstrating a specific interaction between PPARgamma and the aP2 promoter, nor affected lipogenesis in 3T3-L1 cells. Altogether, these data characterized a functional promoter of the human aP2 gene; its in vitro pharmacological regulation in PPARgamma-mediated reporter-gene assay may represent an interesting complement or an alternative to time-consuming procedures aiming at discriminating PPAR ligands with low lipogenic properties.
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Affiliation(s)
- Yves Rival
- Centre de Recherche Pierre Fabre, 17 Avenue Jean Moulin, 81106 Castres Cédex, France
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Monnier L, Sauvanet JP. Pioglitazone, insulinosensibilité et diabète de type 2 : données récentes. ANNALES D'ENDOCRINOLOGIE 2004; 65:136-48. [PMID: 15247874 DOI: 10.1016/s0003-4266(04)95662-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Thiazolidinediones ("glitazones") were recently added to the oral treatment of type 2 diabetes. Two glitazones are available in France, pioglitazone and rosiglitazone, which progressively were granted broader therapeutic indications since their launch in 2002. This review presents the most recent pioglitazone pharmacological and clinical data, with a particular emphasis on the QUARTET clinical study program results. Available information generates perspectives and hopes: prevention of the progressive decline in beta-pancreatic cell function (and possibly, prevention of type 2 diabetes in at-risk subjects), cardiovascular prevention in type 2 diabetic patients depending on the results of the ongoing prospective morbi-mortality studies in high risk type 2 diabetic patients.
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Affiliation(s)
- L Monnier
- Service des maladies métaboliques, hôpital Lapeyronie, CHU de Montpellier.
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Pégorier JP, Girard J. Thiazolidinediones et insulino-sensibilité : rôle du récepteur nucléaire PPARγ. ANNALES D'ENDOCRINOLOGIE 2004; 65:65-72. [PMID: 15122095 DOI: 10.1016/s0003-4266(04)95633-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- J-P Pégorier
- Institut Cochin, département d'Endocrinologie, INSERM U 567, CNRS UMR 8104, Université Paris V René Descartes, 24, rue du Faubourg Saint Jacques, 75014 Paris, France.
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Yu C, Chen L, Luo H, Chen J, Cheng F, Gui C, Zhang R, Shen J, Chen K, Jiang H, Shen X. Binding analyses between Human PPARgamma-LBD and ligands. Surface plasmon resonance biosensor assay correlating with circular dichroic spectroscopy determination and molecular docking. ACTA ACUST UNITED AC 2004; 271:386-97. [PMID: 14717706 DOI: 10.1046/j.1432-1033.2003.03937.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The binding characteristics of a series of PPARgamma ligands (GW9662, GI 262570, cis-parinaric acid, 15-deoxy-Delta(12,14)-prostaglandin J(2), LY171883, indomethacin, linoleic acid, palmitic acid and troglitazone) to human PPARgamma ligand binding domain have been investigated for the first time by using surface plasmon resonance biosensor technology, CD spectroscopy and molecular docking simulation. The surface plasmon resonance biosensor determined equilibrium dissociation constants (KD values) are in agreement with the results reported in the literature measured by other methods, indicating that the surface plasmon resonance biosensor can assume a direct assay method in screening new PPARgamma agonists or antagonists. Conformational changes of PPARgamma caused by the ligand binding were detected by CD determination. It is interesting that the thermal stability of the receptor, reflected by the increase of the transition temperature (T(m)), was enhanced by the binding of the ligands. The increment of the transition temperature (DeltaT(m)) of PPARgamma owing to ligand binding correlated well with the binding affinity. This finding implies that CD could possibly be a complementary technology with which to determine the binding affinities of ligands to PPARgamma. Molecular docking simulation provided reasonable and reliable binding models of the ligands to PPARgamma at the atomic level, which gave a good explanation of the structure-binding affinity relationship for the ligands interacting with PPARgamma. Moreover, the predicted binding free energies for the ligands correlated well with the binding constants measured by the surface plasmon resonance biosensor, indicating that the docking paradigm used in this study could possibly be employed in virtual screening to discover new PPARgamma ligands, although the docking program cannot accurately predict the absolute ligand-PPARgamma binding affinity.
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Affiliation(s)
- Changying Yu
- Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Rangwala SM, Rhoades B, Shapiro JS, Rich AS, Kim JK, Shulman GI, Kaestner KH, Lazar MA. Genetic modulation of PPARgamma phosphorylation regulates insulin sensitivity. Dev Cell 2003; 5:657-63. [PMID: 14536066 DOI: 10.1016/s1534-5807(03)00274-0] [Citation(s) in RCA: 173] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Obesity-associated diabetes is epidemic in industrialized societies. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) is highly expressed in adipose tissue and the presumed molecular target for antidiabetic thiazolidinedione drugs that reverse insulin resistance but also promote weight gain. Phosphorylation reduces the activity of PPARgamma in vitro, but physiological relevance has not been demonstrated. We have studied mice homozygous for a mutation (S112A) that prevents PPARgamma phosphorylation. Surprisingly, the weights and adipose mass of PPARgamma-S112A mice are not greater than wild-type. Remarkably, however, genetic prevention of PPARgamma phosphorylation preserves insulin sensitivity in the setting of diet-induced obesity. Underlying this protection are smaller fat cells, elevated serum adiponectin, and reduced free fatty acid levels. Thus, the phosphorylation state of PPARgamma modulates insulin sensitivity. Compounds that prevent PPARgamma phosphorylation or ligands that induce the conformation of nonphosphorylated PPARgamma may selectively enhance insulin sensitivity without increasing body weight.
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MESH Headings
- Adiponectin
- Adipose Tissue/metabolism
- Adipose Tissue, Brown
- Alanine/genetics
- Amino Acid Substitution
- Animals
- Blood Glucose/metabolism
- Blotting, Southern
- Body Weight
- Cell Size
- Cells, Cultured
- Culture Media, Conditioned/pharmacology
- Dose-Response Relationship, Drug
- Embryo, Mammalian
- Fatty Acids, Nonesterified/blood
- Female
- Gene Expression
- Glucose/metabolism
- Glucose Tolerance Test
- Immunoblotting
- Insulin/metabolism
- Insulin/pharmacology
- Insulin/physiology
- Insulin Resistance
- Intercellular Signaling Peptides and Proteins
- Leptin/blood
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic/blood
- Mice, Transgenic/genetics
- Mutation
- Obesity/blood
- Obesity/chemically induced
- Phosphorylation
- Proteins/genetics
- Proteins/metabolism
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Cytoplasmic and Nuclear/physiology
- Serine/genetics
- Time Factors
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription Factors/physiology
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Affiliation(s)
- Shamina M Rangwala
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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45
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Berger JP, Petro AE, Macnaul KL, Kelly LJ, Zhang BB, Richards K, Elbrecht A, Johnson BA, Zhou G, Doebber TW, Biswas C, Parikh M, Sharma N, Tanen MR, Thompson GM, Ventre J, Adams AD, Mosley R, Surwit RS, Moller DE. Distinct properties and advantages of a novel peroxisome proliferator-activated protein [gamma] selective modulator. Mol Endocrinol 2003; 17:662-76. [PMID: 12554792 DOI: 10.1210/me.2002-0217] [Citation(s) in RCA: 273] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Antidiabetic thiazolidinediones (TZDs) and non-TZD compounds have been shown to serve as agonists of the peroxisome proliferator-activated receptor gamma (PPARgamma). Here, we report the identification and characterization of a novel non-TZD selective PPARgamma modulator (nTZDpa). nTZDpa bound potently to PPARgamma with high selectivity vs. PPARalpha or PPARdelta. In cell-based assays for transcriptional activation, nTZDpa served as a selective, potent PPARgamma partial agonist and was able to antagonize the activity of PPARgamma full agonists. nTZDpa also displayed partial agonist effects when its ability to promote adipogenesis in 3T3-L1 cells was evaluated. Assessment of protein conformation using protease protection or solution nuclear magnetic resonance spectroscopy methods showed that nTZDpa produced altered PPARgamma conformational stability vs. full agonists, thereby establishing a physical basis for its observed partial agonism. DNA microarray analysis of RNA from 3T3-L1 adipocytes treated with nTZDpa or several structurally diverse PPARgamma full agonists demonstrated qualitative differences in the affected gene expression profile for nTZDpa. Chronic treatment of fat-fed, C57BL/6J mice with nTZDpa or a TZD full agonist ameliorated hyperglycemia and hyperinsulinemia. However, unlike the TZD, nTZDpa caused reductions in weight gain and adipose depot size. Feed efficiency was also substantially diminished. Unlike TZDs, nTZDpa did not cause cardiac hypertrophy in mice. When a panel of PPARgamma target genes was examined in white adipose tissue, nTZDpa produced a different in vivo expression pattern vs. the full agonist. These findings establish that novel selective PPARgamma modulators can produce altered receptor conformational stability leading to distinctive gene expression profiles, reduced adipogenic cellular effects, and potentially improved in vivo biological responses. Such compounds may lead to preferred therapies for diabetes, obesity, or metabolic syndrome.
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Affiliation(s)
- Joel P Berger
- RY80N-C31, Merck Research Laboratories, 126 East Lincoln Avenue, Rahway, New Jersey 07065, USA.
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Banerjee RR, Lazar MA. Resistin: molecular history and prognosis. J Mol Med (Berl) 2003; 81:218-26. [PMID: 12700889 DOI: 10.1007/s00109-003-0428-9] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2002] [Accepted: 01/23/2003] [Indexed: 01/15/2023]
Abstract
Obesity and diabetes have reached epidemic proportions worldwide. The antidiabetic thiazolidinedione (TZD) drugs are insulin-sensitizing agents now widely used in the treatment of type 2 diabetes. TZDs are ligands for the nuclear hormone receptor peroxisome proliferator activated receptor gamma, which is a master regulator of adipogenesis and adipocyte metabolism. The molecular mechanisms by which TZDs improve insulin sensitivity have not been fully identified. Here we consider a novel secreted factor first identified as a TZD-suppressible gene in mouse adipocytes, called resistin, and discuss what is currently known about resistin regulation and function in mouse and human.
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Affiliation(s)
- Ronadip R Banerjee
- Division of Endocrinology, Diabetes, and Metabolism, Penn Diabetes Center, University of Pennsylvania School of Medicine, 415 Curie Blvd., Philadelphia, PA 19104-6149, USA
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Bollheimer LC, Kagerbauer SM, Buettner R, Kemptner DM, Palitzsch KD, Schölmerich J, Hügl SR. Synergistic effects of troglitazone and oleate on the translatability of preproinsulin mRNA from INS-1 cells. Biochem Pharmacol 2002; 64:1629-36. [PMID: 12429352 DOI: 10.1016/s0006-2952(02)01352-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glitazones are known to modulate fatty acid-induced effects on insulin secretion in the pancreatic beta-cell. The present study focused on combined effects of troglitazone and oleate on preproinsulin (PPI) biosynthesis. Insulin-producing INS-1 cells were incubated for 4 hr at 11.2mM glucose in the presence (O(+)) or absence (O(-)) of 200 microM oleate with (T(+)) or without (T(-)) 10 microM troglitazone. After cell lysis, cytoplasmic RNA was extracted and employed for Northern blotting and corresponding in vitro translation. Compared with untreated controls (CTRL=O(-)/T(-)), the cellular content of PPI-mRNA from cells which had been simultaneously treated by troglitazone and oleate (O(+)/T(+)) was significantly diminished (O(+)/T(+)=75+/-10% x CTRL; P=0.015). The PPI-mRNA content from those cells which had been exclusively exposed either to oleate (O(+)/T(-)) or troglitazone (O(-)/T(+)) did not significantly differ from that of the untreated controls. In spite of that decreased PPI-mRNA content, in vitro translation revealed the highest yield of newly synthesized PPI in RNA samples from those cells which had been simultaneously exposed to oleate and troglitazone before (O(+)/T(+)=1.6+/-0.3 x CTRL; P=0.01). It is concluded that troglitazone and oleate synergistically affect the translational rate at the level of the PPI-mRNA molecule.
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Affiliation(s)
- L Cornelius Bollheimer
- Department of Internal Medicine I, University of Regensburg, 93042, Regensburg, Germany.
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Abstract
Although adipose tissue has long been considered to be metabolically passive and primarily responsible for energy storage, recent scientific advances have dramatically altered our understanding of the function of this ubiquitous tissue. The fat cell is a transducer of energy supply for the changing metabolic needs of the body, modulating glucose homeostasis, hypothalamic function, sympathetic output, vascular tone, immune response, and reproduction. Through endocrine/autocrine and paracrine actions, adipocyte-derived molecules defend the body during periods of energy deficit and stress. With the development of obesity, maladaptive responses to adipose excess result in pathologic states of inflammation, coagulopathy, and altered insulin sensitivity.
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Affiliation(s)
- Frank B Diamond
- Department of Pediatrics, University of South Florida, College of Medicine, Tampa 33612, USA
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Forman BM. The antidiabetic agent LG100754 sensitizes cells to low concentrations of peroxisome proliferator-activated receptor gamma ligands. J Biol Chem 2002; 277:12503-6. [PMID: 11877384 DOI: 10.1074/jbc.c200004200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin resistance and non-insulin-dependent diabetes mellitus are major causes of morbidity and mortality in industrialized nations. Despite the alarming rise in the prevalence of this disorder, the initial molecular events that promote insulin resistance remain unclear. The data presented here demonstrate that LG100754, an antidiabetic RXR ligand, defines a novel type of nuclear receptor agonist. Surprisingly, LG100754 has minimal intrinsic transcriptional activity, instead it enhances the potency of proliferator-activated receptor (PPAR) gamma-retinoid X receptor heterodimers for PPARgamma ligands. The ability of LG100754 to both increase PPARgamma sensitivity and relieve insulin resistance implies that a deficiency in endogenous PPARgamma ligands may represent an early step in the development of insulin resistance.
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Affiliation(s)
- Barry Marc Forman
- City of Hope National Medical Center, Division of Molecular Medicine, The Gonda Diabetes & Genetic Research Center, 1500 East Duarte Road, Duarte, CA 91010, USA.
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Abstract
The thiazolidinediones (TZDs) or 'glitazones' are a new class of oral antidiabetic drugs that improve metabolic control in patients with type 2 diabetes through the improvement of insulin sensitivity. TZDs exert their antidiabetic effects through a mechanism that involves activation of the gamma isoform of the peroxisome proliferator-activated receptor (PPAR gamma), a nuclear receptor. TZD-induced activation of PPAR gamma alters the transcription of several genes involved in glucose and lipid metabolism and energy balance, including those that code for lipoprotein lipase, fatty acid transporter protein, adipocyte fatty acid binding protein, fatty acyl-CoA synthase, malic enzyme, glucokinase and the GLUT4 glucose transporter. TZDs reduce insulin resistance in adipose tissue, muscle and the liver. However, PPAR gamma is predominantly expressed in adipose tissue. It is possible that the effect of TZDs on insulin resistance in muscle and liver is promoted via endocrine signalling from adipocytes. Potential signalling factors include free fatty acids (FFA) (well-known mediators of insulin resistance linked to obesity) or adipocyte-derived tumour necrosis factor-alpha (TNF-alpha), which is overexpressed in obesity and insulin resistance. Although there are still many unknowns about the mechanism of action of TZDs in type 2 diabetes, it is clear that these agents have the potential to benefit the full 'insulin resistance syndrome' associated with the disease. Therefore, TZDs may also have potential benefits on the secondary complications of type 2 diabetes, such as cardiovascular disease.
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Affiliation(s)
- Hans Hauner
- Diabetes Research Institute, Heinrich-Heine University, Düsseldorf, Germany.
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