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Gaudet D, Pall D, Watts GF, Nicholls SJ, Rosenson RS, Modesto K, San Martin J, Hellawell J, Ballantyne CM. Plozasiran (ARO-APOC3) for Severe Hypertriglyceridemia: The SHASTA-2 Randomized Clinical Trial. JAMA Cardiol 2024:2817469. [PMID: 38583092 PMCID: PMC11000138 DOI: 10.1001/jamacardio.2024.0959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 03/22/2024] [Indexed: 04/08/2024]
Abstract
Importance Severe hypertriglyceridemia (sHTG) confers increased risk of atherosclerotic cardiovascular disease (ASCVD), nonalcoholic steatohepatitis, and acute pancreatitis. Despite available treatments, persistent ASCVD and acute pancreatitis-associated morbidity from sHTG remains. Objective To determine the tolerability, efficacy, and dose of plozasiran, an APOC3-targeted small interfering-RNA (siRNA) drug, for lowering triglyceride and apolipoprotein C3 (APOC3, regulator of triglyceride metabolism) levels and evaluate its effects on other lipid parameters in patients with sHTG. Design, Setting, and Participants The Study to Evaluate ARO-APOC3 in Adults With Severe Hypertriglyceridemia (SHASTA-2) was a placebo-controlled, double-blind, dose-ranging, phase 2b randomized clinical trial enrolling adults with sHTG at 74 centers across the US, Europe, New Zealand, Australia, and Canada from May 31, 2021, to August 31, 2023. Eligible patients had fasting triglyceride levels in the range of 500 to 4000 mg/dL (to convert to millimoles per liter, multiply by 0.0113) while receiving stable lipid-lowering treatment. Interventions Participants received 2 subcutaneous doses of plozasiran (10, 25, or 50 mg) or matched placebo on day 1 and at week 12 and were followed up through week 48. Main Outcomes and Measures The primary end point evaluated the placebo-subtracted difference in means of percentage triglyceride change at week 24. Mixed-model repeated measures were used for statistical modeling. Results Of 229 patients, 226 (mean [SD] age, 55 [11] years; 176 male [78%]) were included in the primary analysis. Baseline mean (SD) triglyceride level was 897 (625) mg/dL and plasma APOC3 level was 32 (16) mg/dL. Plozasiran induced significant dose-dependent placebo-adjusted least squares (LS)-mean reductions in triglyceride levels (primary end point) of -57% (95% CI, -71.9% to -42.1%; P < .001), driven by placebo-adjusted reductions in APOC3 of -77% (95% CI, -89.1% to -65.8%; P < .001) at week 24 with the highest dose. Among plozasiran-treated patients, 144 of 159 (90.6%) achieved a triglyceride level of less than 500 mg/dL. Plozasiran was associated with dose-dependent increases in low-density lipoprotein cholesterol (LDL-C) level, which was significant in patients receiving the highest dose (placebo-adjusted LS-mean increase 60% (95% CI, 31%-89%; P < .001). However, apolipoprotein B (ApoB) levels did not increase, and non-high-density lipoprotein cholesterol (HDL-C) levels decreased significantly at all doses, with a placebo-adjusted change of -20% at the highest dose. There were also significant durable reductions in remnant cholesterol and ApoB48 as well as increases in HDL-C level through week 48. Adverse event rates were similar in plozasiran-treated patients vs placebo. Serious adverse events were mild to moderate, not considered treatment related, and none led to discontinuation or death. Conclusions and Relevance In this randomized clinical trial of patients with sHTG, plozasiran decreased triglyceride levels, which fell below the 500 mg/dL threshold of acute pancreatitis risk in most participants. Other triglyceride-related lipoprotein parameters improved. An increase in LDL-C level was observed but with no change in ApoB level and a decrease in non-HDL-C level. The safety profile was generally favorable at all doses. Additional studies will be required to determine whether plozasiran favorably modulates the risk of sHTG-associated complications. Trial Registration ClinicalTrials.gov Identifier: NCT04720534.
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Affiliation(s)
- Daniel Gaudet
- ECOGENE-21 QC, Department of Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Denes Pall
- Department of Medical Clinical Pharmacology, University of Debrecen, Debrecen, Hungary
| | - Gerald F. Watts
- Department of Cardiology, Royal Perth Hospital, School of Medicine, University of Western Australia, Perth, Western Australia, Australia
| | - Stephen J. Nicholls
- Victorian Heart Institute, Monash University, Melbourne, Victoria, Australia
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Rani R, Syngkli S, Nongkhlaw J, Das B. Expression and characterisation of human glycerol kinase: the role of solubilising agents and molecular chaperones. Biosci Rep 2023; 43:BSR20222258. [PMID: 37021775 PMCID: PMC10130975 DOI: 10.1042/bsr20222258] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 03/11/2023] [Accepted: 04/06/2023] [Indexed: 04/07/2023] Open
Abstract
BACKGROUND Glycerol kinase (GK; EC 2.7.1.30) facilitates the entry of glycerol into pathways of glucose and triglyceride metabolism and may play a potential role in Type 2 diabetes mellitus (T2DM). However, the detailed regulatory mechanisms and structure of the human GK are unknown. METHODS The human GK gene was cloned into the pET-24a(+) vector and over-expressed in Escherichia coli BL21 (DE3). Since the protein was expressed as inclusion bodies (IBs), various culture parameters and solubilising agents were used but they did not produce bioactive His-GK; however, co-expression of His-GK with molecular chaperones, specifically pKJE7, achieved expression of bioactive His-GK. The overexpressed bioactive His-GK was purified using coloumn chromatography and characterised using enzyme kinetics. RESULTS The overexpressed bioactive His-GK was purified apparently to homogeneity (∼295-fold) and characterised. The native His-GK was a dimer with a monomeric molecular weight of ∼55 kDa. Optimal enzyme activity was observed in TEA buffer (50 mM) at 7.5 pH. K+ (40 mM) and Mg2+ (2.0 mM) emerged as prefered metal ions for His-GK activity with specific activity 0.780 U/mg protein. The purified His-GK obeyed standard Michaelis-Menten kinetics with Km value of 5.022 µM (R2=0.927) for its substrate glycerol; whereas, that for ATP and PEP was 0.767 mM (R2=0.928) and 0.223 mM (R2=0.967), respectively. Other optimal parameters for the substrate and co-factors were also determined. CONCLUSION The present study demonstrates that co-expression of molecular chaperones assists with the expression of bioactive human GK for its characterisation.
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Affiliation(s)
- Riva Mary Rani
- Biological Chemistry Laboratory, Department of Zoology, North-Eastern Hill University, Shillong 793022, India
| | - Superior Syngkli
- Biological Chemistry Laboratory, Department of Zoology, North-Eastern Hill University, Shillong 793022, India
| | - Joplin Nongkhlaw
- Biological Chemistry Laboratory, Department of Zoology, North-Eastern Hill University, Shillong 793022, India
| | - Bidyadhar Das
- Biological Chemistry Laboratory, Department of Zoology, North-Eastern Hill University, Shillong 793022, India
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Rani-AGARWAL N, Sarovar BHAVESH N, KACHHAWA G, Fatai OYEYEMI B. Metabolic profiling of Serum and urine in preeclampsia and gestational diabetes in early pregnancy. MEDICINE IN DRUG DISCOVERY 2022. [DOI: 10.1016/j.medidd.2022.100143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Glycerol-3-phosphate phosphatase operates a glycerol shunt in pancreatic β-cells that controls insulin secretion and metabolic stress. Mol Metab 2022; 60:101471. [PMID: 35272070 PMCID: PMC8972011 DOI: 10.1016/j.molmet.2022.101471] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/20/2022] [Accepted: 03/03/2022] [Indexed: 11/23/2022] Open
Abstract
Objective The recently identified glycerol-3-phosphate (Gro3P) phosphatase (G3PP) in mammalian cells, encoded by the PGP gene, was shown to regulate glucose, lipid and energy metabolism by hydrolyzing Gro3P and to control glucose-stimulated insulin secretion (GSIS) in β-cells, in vitro. However, whether G3PP regulates β-cell function and insulin secretion in vivo is not known. Methods We now examined the role of G3PP in the control of insulin secretion in vivo, β-cell function and glucotoxicity in inducible β-cell specific G3PP-KO (BKO) mice. Inducible BKO mice were generated by crossing floxed-G3PP mice with Mip-Cre-ERT (MCre) mice. All the in vivo studies were done using BKO and control mice fed normal diet and the ex vivo studies were done using pancreatic islets from these mice. Results BKO mice, compared to MCre controls, showed increased body weight, adiposity, fed insulinemia, enhanced in vivo GSIS, reduced plasma triglycerides and mild glucose intolerance. Isolated BKO mouse islets incubated at high (16.7 mM), but not at low or intermediate glucose (3 and 8 mM), showed elevated GSIS, Gro3P content as well as increased levels of metabolites and signaling coupling factors known to reflect β-cell activation for insulin secretion. BKO islets also showed reduced glycerol release and increased O2 consumption and ATP production at high glucose only. BKO islets chronically exposed to elevated glucose levels showed increased apoptosis, reduced insulin content and decreased mRNA expression of β-cell differentiation markers, Pdx-1, MafA and Ins-2. Conclusions The results demonstrate that β-cells are endowed with a “glycerol shunt”, operated by G3PP that regulates β-cell metabolism, signaling and insulin secretion in vivo, primarily at elevated glucose concentrations. We propose that the glycerol shunt plays a role in preventing insulin hypersecretion and excess body weight gain and contributes to β-cell mass preservation in the face of hyperglycemia. G3PP operates a glycerol shunt in β-cells to remove excess glucose as glycerol. Inducible β-cell specific G3PP-KO (BKO) mice show hyperinsulinemia. BKO mice show enhanced body weight and glucose induced insulin secretion. BKO isolated islets show elevated insulin secretion only at high glucose. Chronic exposure of BKO isolated islets to high glucose enhances glucotoxicity.
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Phosphoglycolate phosphatase homologs act as glycerol-3-phosphate phosphatase to control stress and healthspan in C. elegans. Nat Commun 2022; 13:177. [PMID: 35017476 PMCID: PMC8752807 DOI: 10.1038/s41467-021-27803-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 12/07/2021] [Indexed: 01/06/2023] Open
Abstract
Metabolic stress due to nutrient excess and lipid accumulation is at the root of many age-associated disorders and the identification of therapeutic targets that mimic the beneficial effects of calorie restriction has clinical importance. Here, using C. elegans as a model organism, we study the roles of a recently discovered enzyme at the heart of metabolism in mammalian cells, glycerol-3-phosphate phosphatase (G3PP) (gene name Pgp) that hydrolyzes glucose-derived glycerol-3-phosphate to glycerol. We identify three Pgp homologues in C. elegans (pgph) and demonstrate in vivo that their protein products have G3PP activity, essential for glycerol synthesis. We demonstrate that PGPH/G3PP regulates the adaptation to various stresses, in particular hyperosmolarity and glucotoxicity. Enhanced G3PP activity reduces fat accumulation, promotes healthy aging and acts as a calorie restriction mimetic at normal food intake without altering fertility. Thus, PGP/G3PP can be considered as a target for age-related metabolic disorders.
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Lebeck J, Brock B. Plasma glycerol levels in men with hypertriglyceridemia. Scandinavian Journal of Clinical and Laboratory Investigation 2021; 81:298-302. [PMID: 33819108 DOI: 10.1080/00365513.2021.1904282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
When plasma triglyceride is assessed in standard laboratories, it is a measurement of plasma glycerol after hydrolysis of triglycerides into fatty acids and glycerol. In most patients, the plasma level of free glycerol will only marginally influence the measurement of plasma triglyceride. However, in rare cases elevated free glycerol concentrations causes pseudohypertriglyceridemia and blanking for free glycerol becomes important. In this study, we investigated the plasma free glycerol level in 100 adult men with mild to moderate hypertriglyceridemia to assess the need for providing a free glycerol measurement in our clinical biochemistry department. The plasma samples were obtained in our blood sampling facility that receives both in- and outpatients. The highest plasma level of free glycerol observed was 300 µmol/L and in 99% of the investigated men the inclusion of plasma free glycerol in the measurement of plasma triglyceride cause a less than 10% false increase in plasma triglyceride. A weak positive correlation between the plasma levels of free glycerol and triglyceride was observed. When subdividing the cohort into mild and moderate hypertriglyceridemia, the positive correlation was only maintained in the moderate hypertriglyceridemia group that also demonstrated a 23% higher plasma glycerol level than men with mild hypertriglyceridemia. We conclude that even though glycerol blanking is relevant in rare occasions, then this study does not support providing such a measurement in our department. The positive correlation between free glycerol and triglyceride in this cohort likely reflects a shared association with metabolic dysregulation.
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Affiliation(s)
- Janne Lebeck
- Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark.,Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Birgitte Brock
- Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark.,Steno Diabetes Center Copenhagen, Gentofte, Denmark
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Lamiquiz-Moneo I, Mateo-Gallego R, Fernández-Pardo J, López-Ariño C, Marco-Benedí V, Bea AM, Ferraro L, Jarauta E, Cenarro A, Civeira F. Glycerol kinase deficiency in adults: Description of 4 novel cases, systematic review and development of a clinical diagnostic score. Atherosclerosis 2020; 315:24-32. [PMID: 33212314 DOI: 10.1016/j.atherosclerosis.2020.10.897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 10/08/2020] [Accepted: 10/29/2020] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND AIMS Glycerol kinase deficiency (GKD) is a rare genetic disorder characterized by hyperglycerolemia and glyceroluria, which could be misdiagnosed as a moderate to severe hypertriglyceridemia (HTG). We aimed to describe four novel cases of GKD, to complete a systematic review of all cases of isolated GKD published so far, and to develop a suspicion clinical diagnostic score for GKD. METHODS We reported four cases with suspicion of GKD and compared their phenotype with 584 males with triglycerides (TG) > 300 mg/dL, selected as control group (HTG non-GKD). The GK gene was sequenced in all cases. Lipoprotein particle concentrations were measured in all cases with GKD. The systematic review involved a PubMed, Cochrane and Scopus databases search to identify anthropometric and biochemical characteristics of all described cases with GKD. RESULTS The systematic review retrieved a total of 15 articles involving 39 subjects with GKD. GKD cases reported a history of high TG levels resistant to lipid-lowering therapy. Compared to GKD subjects (n = 43), HTG non-GKD subjects (n = 584) showed significantly higher BMI, total cholesterol, non-HDL cholesterol and gamma-glutamyltransferase, significantly lower HDL cholesterol and TG, and higher prevalence of diabetes. The proposed diagnostic score was significantly higher in GKD than in HTG non-GKD subjects. CONCLUSIONS This is the first systematic review that compiles all GKD cases reported to date including 4 novel cases, and examine the differential GKD phenotype compared to other types of HTG. The proposed score would have a broad utility in clinical practice to avoid unwarranted lipid lowering treatment in GKD patients.
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Affiliation(s)
- Itziar Lamiquiz-Moneo
- Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Zaragoza, Spain.
| | - Rocio Mateo-Gallego
- Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Zaragoza, Spain; Departamento de Fisiatría y Enfermería, Facultad de Ciencias de la Salud y del Deporte, Universidad de Zaragoza, Huesca, Spain
| | - Jacinto Fernández-Pardo
- Servicio de Medicina Interna (Unidad de Lípidos), Hospital General Universitario Reina Sofía, Murcia, Spain
| | - Chuan López-Ariño
- Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Zaragoza, Spain
| | - Victoria Marco-Benedí
- Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Zaragoza, Spain
| | - Ana M Bea
- Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Zaragoza, Spain
| | - Lia Ferraro
- Servicio de Medicina Interna (Unidad de Lípidos), Hospital General Universitario Reina Sofía, Murcia, Spain
| | - Estibaliz Jarauta
- Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Zaragoza, Spain; Departamento de Medicina, Psiquiatría y Dermatología, Facultad de Medicina, Universidad de Zaragoza, Zaragoza, Spain
| | - Ana Cenarro
- Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Zaragoza, Spain; Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
| | - Fernando Civeira
- Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Zaragoza, Spain; Departamento de Medicina, Psiquiatría y Dermatología, Facultad de Medicina, Universidad de Zaragoza, Zaragoza, Spain
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Miao L, Su F, Yang Y, Liu Y, Wang L, Zhan Y, Yin R, Yu M, Li C, Yang X, Ge C. Glycerol kinase enhances hepatic lipid metabolism by repressing nuclear receptor subfamily 4 group A1 in the nucleus. Biochem Cell Biol 2020; 98:370-377. [DOI: 10.1139/bcb-2019-0317] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Glycerol kinase (GYK) plays a critical role in hepatic metabolism by converting glycerol to glycerol 3-phosphate in an ATP-dependent reaction. GYK isoform b is the only glycerol kinase present in whole cells, and has a non-enzymatic moonlighting function in the nucleus. GYK isoform b acts as a co-regulator of nuclear receptor subfamily 4 group A1 (NR4A1) and participates in the regulation of hepatic glucose metabolism by protein–protein interaction with NR4A1. Herein, GYK expression was found to upregulate the expression of NR4A1-mediated lipid metabolism-related genes (SREBP1C, FASN, ACACA, and GPAM) in HEK293T and L02 cells, and in mouse in vivo studies. GYK expression increased blood levels of cholesterol, triglyceride, and high-density lipoprotein cholesterol, but not low-density lipoprotein cholesterol levels. It enhanced the transcriptional activity of Nr4a1 target genes by negatively cooperating with NR4A1 and its enzymatic activity or by other undefined moonlighting functions. This enhancement was observed in both normal and diabetic mice. We also found a feed-forward regulation loop between GYK and NR4A1, serving as part of a GYK-NR4A1 regulatory mechanism in hepatic metabolism. Thus, GYK regulates the effect of NR4A1 on hepatic lipid metabolism in normal and diabetic mice, partially through the cooperation of GYK and NR4A1.
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Affiliation(s)
- Lili Miao
- Department of Experimental Hematology and Biochemistry, Beijing Institute of Radiation Medicine, Beijing 100850, China
- Graduate School of Anhui Medical University, Hefei 230032, China
| | - Fei Su
- Department of Experimental Hematology and Biochemistry, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Yongsheng Yang
- Department of Experimental Hematology and Biochemistry, Beijing Institute of Radiation Medicine, Beijing 100850, China
- Institute of Acu-moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Yue Liu
- Department of Experimental Hematology and Biochemistry, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Lei Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing 102206, China
| | - Yiqun Zhan
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing 102206, China
| | - Ronghua Yin
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing 102206, China
| | - Miao Yu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing 102206, China
| | - Changyan Li
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing 102206, China
| | - Xiaoming Yang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing 102206, China
| | - Changhui Ge
- Department of Experimental Hematology and Biochemistry, Beijing Institute of Radiation Medicine, Beijing 100850, China
- Graduate School of Anhui Medical University, Hefei 230032, China
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Pendharkar SA, Singh RG, Petrov MS. Pro-inflammatory cytokine-induced lipolysis after an episode of acute pancreatitis. Arch Physiol Biochem 2018; 124:401-409. [PMID: 29235373 DOI: 10.1080/13813455.2017.1415359] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
CONTEXT Pro-inflammatory cytokine-stimulated lipolysis is one of the mechanisms underlying the pathogenesis of type 2 diabetes. However, whether it plays a role in the pathogenesis of post-pancreatitis diabetes mellitus (PPDM) remains unknown. OBJECTIVE To investigate the associations between markers of lipid metabolism and pro-inflammatory cytokines in individuals after acute pancreatitis (AP) in general, and in individuals with abnormal glucose metabolism (AGM) following AP in particular. METHODS Fasting blood samples were collected to measure markers of lipid metabolism (apolipoprotein-B, cholesterol, free fatty acids (FFA), glycerol, high and low-density lipoproteins, triglycerides) and cytokines (interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, and tumour necrosis factor (TNF) α). Linear regression analysis was conducted. Four statistical models were used to adjust for patient- and pancreatitis-related characteristics. RESULTS A total of 83 patients were recruited. IL-6 was significantly associated with glycerol in all models (p < .05), with glycerol levels increasing by 106% in individuals with AGM after AP (p <.05) compared to a 30.3% increase in individuals with normal glucose metabolism (NGM) (p >.05). TNFα was significantly associated with FFA (p = .015) in individuals with AGM after AP in the most adjusted model, with FFA levels increasing by 314% in these individuals compared to a 162% decrease in individuals with NGM after AP (p >.05). CONCLUSIONS Lipolysis appears to be an important pathogenetic mechanism in glucose derangements after diseases of the exocrine pancreas. IL-6 and TNFα are the driving forces behind lipolysis in individuals with AGM after AP. Modulation of lipolysis may be a promising therapeutic modality.
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Affiliation(s)
| | - Ruma G Singh
- a School of Medicine , University of Auckland , Auckland , New Zealand
| | - Maxim S Petrov
- a School of Medicine , University of Auckland , Auckland , New Zealand
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Parr LS, Sriram G, Nazarian R, Rahib L, Dipple KM. The ATP-stimulated translocation promoter (ASTP) activity of glycerol kinase plays central role in adipogenesis. Mol Genet Metab 2018; 124:254-265. [PMID: 29960856 DOI: 10.1016/j.ymgme.2018.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 06/05/2018] [Accepted: 06/05/2018] [Indexed: 11/16/2022]
Abstract
Glycerol kinase (GK) is a multifunctional enzyme located at the interface of carbohydrate and fat metabolism. It contributes to both central carbon metabolism and adipogenesis; specifically, through its role as the ATP-stimulated translocation promoter (ASTP). GK overexpression leads to increased ASTP activity and increased fat storage in H4IIE cells. We performed metabolic flux analysis in human GK-overexpressing H4IIE cells and found that overexpressing cells had significantly altered fluxes through central carbon and lipid metabolism including increased flux through the pentose phosphate pathway and increased production of lipids. We also observed an equal contribution of glycerol to carbohydrate metabolism in all cell lines, suggesting that GK's alternate functions rather than its enzymatic function are important for these processes. To further elucidate the contributions of the enzymatic (phosphorylation) and alternative (ASTP) functions of GK in adipogenesis, we performed experiments on mammalian GK and E. coli GK. We determined that the ASTP function of GK (which is absent in E. coli GK) plays a greater role than the enzymatic activity in these processes. These studies further emphasize GK's diverse functionality and provides fundamental insights into the multiple protein functions of glycerol kinase.
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Affiliation(s)
- Lilly S Parr
- Department of Human Genetics, David Geffen School of Medicine at UCLA, 695 Charles E. Young Drive South, Los Angeles, CA 90095-7088, USA
| | - Ganesh Sriram
- Department of Human Genetics, David Geffen School of Medicine at UCLA, 695 Charles E. Young Drive South, Los Angeles, CA 90095-7088, USA; Department of Chemical and Biomolecular Engineering, Henry Samueli School of Engineering and Applied Science at UCLA, 420 Westwood Plaza, Los Angeles, CA 90095, USA; Department of Chemical and Biomolecular Engineering, 1208D Building 90, Chemical and Nuclear Engineering Bldg, University of Maryland, College Park, MD 20742-2111, USA
| | - Ramin Nazarian
- Department of Medicine/Dermatology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA
| | - Lola Rahib
- Biomedical Engineering, Interdepartmental Program, Henry Samueli School of Engineering and Applied Science at UCLA, 420 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Katrina M Dipple
- Department of Human Genetics, David Geffen School of Medicine at UCLA, 695 Charles E. Young Drive South, Los Angeles, CA 90095-7088, USA; Biomedical Engineering, Interdepartmental Program, Henry Samueli School of Engineering and Applied Science at UCLA, 420 Westwood Plaza, Los Angeles, CA 90095, USA; Department of Pediatrics, David Geffen School of Medicine at UCLA, Mattel Children's Hospital at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095-1782, USA; University of Washington, Department of Pediatrics, Seattle Children's Hospital, Division of Genetic Medicine, 4800 Sand Point Way NE, Seattle, WA 98105, USA.
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Tremblay M, Brisson D, Gaudet D. Association study between a polymorphic poly-T repeat sequence in the promoter of the somatostatin gene and metabolic syndrome. BMC MEDICAL GENETICS 2018; 19:130. [PMID: 30053852 PMCID: PMC6062971 DOI: 10.1186/s12881-018-0641-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/04/2018] [Indexed: 01/21/2023]
Abstract
Background Metabolic syndrome is a cluster of factors associated with an increased risk of developing type 2 diabetes mellitus (T2D) and coronary artery disease (CAD). It is a complex disorder resulting from the interaction between various environmental factors and genetic susceptibility. The somatostatin (SST) gene has been shown to regulate a wide range of functions, particularly in energy homeostasis. In addition, low levels of SST have been reported to have effects on the progression of metabolic syndrome components. The aim of this study was therefore to evaluate the association between polymorphic T sequences in the promoter of the SST gene and metabolic syndrome expression. Methods We studied 1725 French-Canadian subjects from a founder population selected on the basis of having a positive family history of dyslipidemia, CAD or T2D. The analysis were performed on four groups created according to the poly T polymorphism length in the 5′ flanking promoter region of SST. Anova, Ancova and logistic regression models and Chi 2 analyses were used to evaluate the association between the poly T polymorphisms and metabolic syndrome components expression. Results Analyses showed that means, frequencies and odds ratio of metabolic syndrome components expression increase as the number of poly-T repeats in the promoter region of SST increases. Women exhibit more significant differences than men. However, the trends are the same in both genders and differences for most of the components are significant in the entire sample. Conclusion Those results suggest that the poly T polymorphisms in the SST promoter region may influence several metabolic processes implicated in metabolic syndrome expression. More analyses are needed to document the mechanisms that could underlie genetic regulation effect of SST on metabolic syndrome components and to clarify its specific role.
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Affiliation(s)
- Monique Tremblay
- Lipidology Unit, Community Genomic Medicine Center, Department of Medicine, Université de Montréal and ECOGENE-21 Clinical and Translational Research Center, 225 St-Vallier Chicoutimi, Québec, G7H 7P2, Canada
| | - Diane Brisson
- Lipidology Unit, Community Genomic Medicine Center, Department of Medicine, Université de Montréal and ECOGENE-21 Clinical and Translational Research Center, 225 St-Vallier Chicoutimi, Québec, G7H 7P2, Canada
| | - Daniel Gaudet
- Lipidology Unit, Community Genomic Medicine Center, Department of Medicine, Université de Montréal and ECOGENE-21 Clinical and Translational Research Center, 225 St-Vallier Chicoutimi, Québec, G7H 7P2, Canada.
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Abstract
This commentary will focus on how we can use our knowledge about the complexity of human disease and its pathogenesis to identify novel approaches to therapy. We know that even for single gene Mendelian disorders, patients with identical mutations often have different presentations and outcomes. This lack of genotype-phenotype correlation led us and others to examine the roles of modifier genes in the context of biological networks. These investigations have utilized vertebrate and invertebrate model organisms. Since one of the goals of research on modifier genes and networks is to identify novel therapeutic targets, the challenges to patient access and compliance because of the high costs of medications for rare genetic diseases must be recognized. A recent article explored protective modifiers, including plastin 3 (PLS3) and coronin 1C (CORO1C), in spinal muscular atrophy (SMA). SMA is an autosomal recessive deficit of survival motor neuron protein (SMN) caused by mutations in SMN1. However, the severity of SMA is determined primarily by the number of SMN2 copies, and this results in significant phenotypic variability. PLS3 was upregulated in siblings who were asymptomatic compared with those who had SMA2 or SMA3, but identical homozygous SMN1 deletions and equal numbers of SMN2 copies. CORO1C was identified by interrogation of the PLS3 interactome. Overexpression of these proteins rescued endocytosis in SMA models. In addition, antisense RNA for upregulation of SMN2 protein expression is being developed as another way of modifying the SMA phenotype. These investigations suggest the practical application of protective modifiers to rescue SMA phenotypes. Other examples of the potential therapeutic value of novel protective modifiers will be discussed, including in Duchenne muscular dystrophy and glycerol kinase deficiency. This work shows that while we live in an exciting era of genomic sequencing, a functional understanding of biology, the impact of its disruption, and possibilities for its repair have never been more important as we search for new therapies.
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Affiliation(s)
- Edward R B McCabe
- March of Dimes Foundation, United States; Department of Pediatrics, David Geffen School of Medicine at UCLA, United States.
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13
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Xue LL, Chen HH, Jiang JG. Implications of glycerol metabolism for lipid production. Prog Lipid Res 2017; 68:12-25. [PMID: 28778473 DOI: 10.1016/j.plipres.2017.07.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 07/06/2017] [Accepted: 07/31/2017] [Indexed: 12/13/2022]
Abstract
Triacylglycerol (TAG) is an important product in oil-producing organisms. Biosynthesis of TAG can be completed through either esterification of fatty acids to glycerol backbone, or through esterification of 2-monoacylglycerol. This review will focus on the former pathway in which two precursors, fatty acid and glycerol-3-phosphate (G3P), are required for TAG formation. Tremendous progress has been made about the enzymes or genes that regulate the biosynthetic pathway of TAG. However, much attention has been paid to the fatty acid provision and the esterification process, while the possible role of G3P is largely neglected. Glycerol is extensively studied on its usage as carbon source for value-added products, but the modification of glycerol metabolism, which is directly associated with G3P synthesis, is seldom recognized in lipid investigations. The relevance among glycerol metabolism, G3P synthesis and lipid production is described, and the role of G3P in glycerol metabolism and lipid production are discussed in detail with an emphasis on how G3P affects lipid production through the modulation of glycerol metabolism. Observations of lipid metabolic changes due to glycerol related disruption in mammals, plants, and microorganisms are introduced. Altering glycerol metabolism results in the changes of final lipid content. Possible regulatory mechanisms concerning the relationship between glycerol metabolism and lipid production are summarized.
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Affiliation(s)
- Lu-Lu Xue
- (a)College of Food and Bioengineering, South China University of Technology, Guangzhou 510640, China; (b)Industrial Crops Research Institute, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | - Hao-Hong Chen
- (a)College of Food and Bioengineering, South China University of Technology, Guangzhou 510640, China
| | - Jian-Guo Jiang
- (a)College of Food and Bioengineering, South China University of Technology, Guangzhou 510640, China.
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14
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Tremblay M, Brisson D, Gaudet D. Association between a polymorphic poly-T repeat sequence in the promoter of the somatostatin gene and hypertension. Hypertens Res 2016; 39:467-74. [PMID: 26818653 DOI: 10.1038/hr.2016.4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 12/07/2015] [Accepted: 12/19/2015] [Indexed: 02/04/2023]
Abstract
Despite the numerous common pathways connecting blood pressure regulation to somatostatin (SST) metabolism, the SST gene has never been seen as a significant blood pressure modulator. The aim of this study was to evaluate the association between a poly-T repeat sequence (rs34872250) in the promoter of the SST gene and blood pressure, according to the obesity status. We genotyped 1918 French-Canadian subjects from a founder population. Analyses were performed according to the length of the poly-T repeat sequence on both alleles and divided into two groups, the 13/13-13/14 group and the 13/15-13/16 group. The effect of age, gender, body mass index, antihypertensive drugs and diabetic status were considered. Systolic, diastolic and mean blood pressures are significantly higher among the 13/15-13/16 group in the whole sample (P<0.05). Whereas the differences remain significant in women, they turn to be non-significant when men are considered alone. The risk of hypertension is increased in the 13/15-13/16 group, particularly among overweight/obese subjects. Systolic blood pressure is significantly higher among overweight/obese carriers of the 13/15-13/16 alleles in the whole sample (P<0.001), in men (P=0.006) and in women (P=0.002), even after correction for age and antihypertensive drugs. These results suggest that the poly-T repeat sequence polymorphism in the promoter of the SST gene is associated with significant variations of blood pressure and could modulate the risk of hypertension, particularly among women.
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Affiliation(s)
- Monique Tremblay
- Lipidology Unit, Community Genomic Medicine Center, Department of Medicine, Université de Montréal, Chicoutimi, Québec, Canada.,ECOGENE-21, Clinical and Translational Research Center, Chicoutimi, Québec, Canada
| | - Diane Brisson
- Lipidology Unit, Community Genomic Medicine Center, Department of Medicine, Université de Montréal, Chicoutimi, Québec, Canada.,ECOGENE-21, Clinical and Translational Research Center, Chicoutimi, Québec, Canada
| | - Daniel Gaudet
- Lipidology Unit, Community Genomic Medicine Center, Department of Medicine, Université de Montréal, Chicoutimi, Québec, Canada.,ECOGENE-21, Clinical and Translational Research Center, Chicoutimi, Québec, Canada
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15
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Backes JM, Dayspring TD, Hoefner DM, Moriarty PM. Hypertriglyceridaemia unresponsive to multiple treatments. BMJ Case Rep 2015; 2015:bcr-2015-210788. [PMID: 26468219 DOI: 10.1136/bcr-2015-210788] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
A 52-year-old man with a longstanding history of hypertriglyceridaemia (approximately 7 mmol/L (600 mg/dL)), unresponsive to treatment, presented to a lipid-specialty clinic. Additional triglyceride-lowering therapies were added with no effect. It was then noted that despite the apparent hypertriglyceridaemia, his serum sample was clear. A 'glycerol blank' was then requested from an advanced lipid laboratory, which reported a triglyceride value of 0.7 mmol/L (62 mg/dL). These findings suggest isolated asymptomatic glycerol kinase deficiency (GKD) or 'pseudohypertriglyceridaemia'. The falsely elevated triglyceride values in such individuals are a result of excess serum glycerol and clinical laboratories measuring glycerol to report triglyceride concentrations. After discontinuation or modification of the patient's primary triglyceride-lowering agents, the lipid panels and triglyceride values remained comparable to previous readings. Recognition of asymptomatic GKD is important to prevent unnecessary treatment and overestimated cardiovascular risk.
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Affiliation(s)
- James M Backes
- Department of Pharmacy Practice, University of Kansas School of Pharmacy, Kansas City, Kansas, USA
| | - Thomas D Dayspring
- Foundation for Health Improvement and Technology, Richmond, Virginia, USA
| | | | - Patrick M Moriarty
- Division of Clinical Pharmacology, Department of Medicine, Kansas University Medical Center, Kansas City, Kansas, USA
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16
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Laforenza U, Bottino C, Gastaldi G. Mammalian aquaglyceroporin function in metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:1-11. [PMID: 26456554 DOI: 10.1016/j.bbamem.2015.10.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/05/2015] [Accepted: 10/07/2015] [Indexed: 11/26/2022]
Abstract
Aquaglyceroporins are integral membrane proteins that are permeable to glycerol as well as water. The movement of glycerol from a tissue/organ to the plasma and vice versa requires the presence of different aquaglyceroporins that can regulate the entrance or the exit of glycerol across the plasma membrane. Actually, different aquaglyceroporins have been discovered in the adipose tissue, small intestine, liver, kidney, heart, skeletal muscle, endocrine pancreas and capillary endothelium, and their differential expression could be related to obesity and the type 2 diabetes. Here we describe the expression and function of different aquaglyceroporins in physiological condition and in obesity and type 2 diabetes, suggesting they are potential therapeutic targets for metabolic disorders.
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Affiliation(s)
| | - Cinzia Bottino
- Department of Molecular Medicine, University of Pavia, Italy
| | - Giulia Gastaldi
- Department of Molecular Medicine, University of Pavia, Italy
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17
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Zhang YH, Van Hove JL, McCabe ER, Dipple KM. Gestational Diabetes Associated with a Novel Mutation (378-379insTT) in the Glycerol Kinase Gene. Mol Genet Metab Rep 2015; 4:42-45. [PMID: 26309814 PMCID: PMC4545508 DOI: 10.1016/j.ymgmr.2015.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Glycerol kinase deficiency (GKD) is an X-linked inborn error of metabolism at the interface of fat and carbohydrate metabolism. We report a male patient with GKD and a novel insertion of TT in exon 5 at position 378 of the GK cDNA (378–379insTT). This resulted in a premature stop codon and 0.8% normal GK activity. The mother is a carrier for this mutation and had gestational diabetes requiring insulin during this pregnancy but not in her previous pregnancy. Given the association between GKD and type 2 diabetes mellitus, it is interesting that the mother had gestational diabetes while carrying an affected fetus. Therefore, GKD is another disease where there may be a maternal–fetal interaction based on genotype. Further investigations may help elucidate the role of GKD in the carrier mother's gestational diabetes. In addition, these studies will provide better-informed counseling to families with GKD regarding the risk to carrier females.
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Affiliation(s)
- Yao H. Zhang
- Department of Pediatrics, David Geffen School of Medicine at UCLA, and Mattel Children's Hospital UCLA, Los Angeles, CA 90095-1752, USA
| | - Johan L. Van Hove
- Department of Pediatrics, Catholic University Leuven, Leuven B3000, Belgium
| | - Edward R.B. McCabe
- Department of Pediatrics, David Geffen School of Medicine at UCLA, and Mattel Children's Hospital UCLA, Los Angeles, CA 90095-1752, USA
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-7088, USA
- Interdepartmental Program, Biomedical Engineering, Henry Samulei School of Engineering and Applied Sciences at UCLA, Los Angeles, CA 90095, USA
| | - Katrina M. Dipple
- Department of Pediatrics, David Geffen School of Medicine at UCLA, and Mattel Children's Hospital UCLA, Los Angeles, CA 90095-1752, USA
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-7088, USA
- Interdepartmental Program, Biomedical Engineering, Henry Samulei School of Engineering and Applied Sciences at UCLA, Los Angeles, CA 90095, USA
- Corresponding author at: Departments of Human Genetics and Pediatrics, David Geffen School of Medicine at UCLA, Gonda Center 5506B, 695 Charles E. Young Drive South, Los Angeles, CA 90095-7088, USA.
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18
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Ho CK, Rahib L, Liao JC, Sriram G, Dipple KM. Mathematical modeling of the insulin signal transduction pathway for prediction of insulin sensitivity from expression data. Mol Genet Metab 2015; 114:66-72. [PMID: 25468647 PMCID: PMC4319670 DOI: 10.1016/j.ymgme.2014.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 10/29/2014] [Accepted: 11/02/2014] [Indexed: 01/09/2023]
Abstract
Mathematical models of biological pathways facilitate a systems biology approach to medicine. However, these models need to be updated to reflect the latest available knowledge of the underlying pathways. We developed a mathematical model of the insulin signal transduction pathway by expanding the last major previously reported model and incorporating pathway components elucidated since the original model was reported. Furthermore, we show that inputting gene expression data of key components of the insulin signal transduction pathway leads to sensible predictions of glucose clearance rates in agreement with reported clinical measurements. In one set of simulations, our model predicted that glycerol kinase knockout mice have reduced GLUT4 translocation, and consequently, reduced glucose uptake. Additionally, a comparison of our extended model with the original model showed that the added pathway components improve simulations of glucose clearance rates. We anticipate this expanded model to be a useful tool for predicting insulin sensitivity in mammalian tissues with altered expression protein phosphorylation or mRNA levels of insulin signal transduction pathway components.
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Affiliation(s)
- Clark K Ho
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science at UCLA, USA
| | - Lola Rahib
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science at UCLA, USA
| | - James C Liao
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science at UCLA, USA; Department of Chemical and Biomolecular Engineering, Henry Samueli School of Engineering and Applied Science at UCLA, USA
| | - Ganesh Sriram
- Department of Chemical and Biomolecular Engineering, Henry Samueli School of Engineering and Applied Science at UCLA, USA; Department of Human Genetics, David Geffen School of Medicine at UCLA, USA
| | - Katrina M Dipple
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science at UCLA, USA; Department of Human Genetics, David Geffen School of Medicine at UCLA, USA; Department of Pediatrics, David Geffen School of Medicine at UCLA, USA; Mattel Children's Hospital at UCLA, USA.
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19
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Backes JM, Dayspring T, Mieras T, Moriarty PM. Pseudohypertriglyceridemia: two cases of probable glycerol kinase deficiency. J Clin Lipidol 2012; 6:469-73. [PMID: 23009783 DOI: 10.1016/j.jacl.2012.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 01/30/2012] [Accepted: 02/02/2012] [Indexed: 10/14/2022]
Abstract
The National Cholesterol Educational Program Adult Treatment Panel's third report define borderline-high, high, and very high triglycerides as serum levels of 150-199 mg/dL, 200-499 mg/dL, and ≥500 mg/dL, respectively. Hypertriglyceridemia (HTG) is generally very responsive to both therapeutic lifestyle changes (TLC), and drug therapy, with niacin, omega-3 fatty acids, fibrates, and statins, each reducing levels by ~10-50%. This paper presents two cases of patients who were aggressively treated for significant HTG with little response to therapy. Although most measured triglyceride (TG) values in these patients were markedly elevated, periodic concentrations were reported as normal. When this occurs, the clinician must immediately think of the diagnosis 'pseudohypertriglyceridemia' or as it is more aptly termed 'glycerolemia' secondary to glycerol kinase deficiency (GKD).
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Affiliation(s)
- James M Backes
- Atherosclerosis and LDL-Apheresis Center, Kansas University Medical Center, Room B440 Mail Stop 4047, Kansas City, KS 66160, USA.
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20
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Kosuga M, Henderson-MacLennan NK, Zhang YH, Huang BL, Dipple KM, McCabe ERB. Glycerol homeostasis and metabolism in glycerol kinase carrier mice. Mol Genet Metab 2011; 103:297-9. [PMID: 21536471 DOI: 10.1016/j.ymgme.2011.02.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Revised: 02/15/2011] [Accepted: 02/15/2011] [Indexed: 10/18/2022]
Abstract
To examine glycerol homeostasis and metabolism is essential for understanding of pathogenesis and evaluation of treatment efficacy in disorders of glycerol metabolism. In this study, we designed the intraperitoneal glycerol tolerance test (IPGlyTT) and studied glycerol tolerance in vivo using glycerol kinase (Gyk) carrier (C) and wild type (WT) mice. Serum glycerol concentrations in WT almost normalized at 90 min after injection, whereas Gyk C mice retained high serum glycerol concentrations at least until 180 min after injection. These results showed that glycerol tolerance was impaired in Gyk C mice compared to WT mice. The IPGlyTT is useful in accessing glycerol homeostasis and metabolism in animal models such as Gyk C mice and will be valuable in assessing therapeutic interventions in Gyk KO mice.
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Affiliation(s)
- Motomichi Kosuga
- Department of Pediatrics, 22-412 MDCC, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095-1752, USA
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21
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Tremblay K, Méthot J, Brisson D, Gaudet D. Etiology and risk of lactescent plasma and severe hypertriglyceridemia. J Clin Lipidol 2011; 5:37-44. [DOI: 10.1016/j.jacl.2010.11.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 10/28/2010] [Accepted: 11/09/2010] [Indexed: 01/12/2023]
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22
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Abstract
Several recent observations suggest a connection between Gaucher
disease, the inherited deficiency of glucocerebrosidase, and the
synucleinopathies. Rare patients have been observed who develop
both Gaucher disease and parkinsonism. Autopsy studies on these
subjects reveal synuclein-positive Lewy bodies and inclusions. An
increased incidence of synucleinopathies also has been noted in
relatives of Gaucher probands. In complementary studies, screening
of patients with parkinsonism has identified a greater than
expected frequency of glucocerebrosidase mutations. These
glucocerebrosidase mutation carriers have a wide spectrum of
associated parkinsonian phenotypes, ranging from classic
L-dopa-responsive Parkinson disease to a phenotype
more characteristic of Lewy body dementia. Despite this
association, the vast majority of Gaucher carriers and patients
with Gaucher disease never develop parkinsonism. However,
mutations in this gene are likely to be a contributing risk factor
in subjects otherwise prone to developing synucleinopathies.
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Affiliation(s)
- Kathleen S. Hruska
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-3708, USA
- *Kathleen S. Hruska:
| | - Ozlem Goker-Alpan
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-3708, USA
| | - Ellen Sidransky
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-3708, USA
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23
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Sriram G, Parr LS, Rahib L, Liao JC, Dipple KM. Moonlighting function of glycerol kinase causes systems-level changes in rat hepatoma cells. Metab Eng 2010; 12:332-40. [PMID: 20399282 DOI: 10.1016/j.ymben.2010.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 04/08/2010] [Accepted: 04/12/2010] [Indexed: 10/19/2022]
Abstract
Glycerol kinase (GK) is an enzyme with diverse (moonlighting) cellular functions. GK overexpression affects central metabolic fluxes substantially; therefore, to elucidate the mechanism underlying these changes, we employed a systems-level evaluation of GK overexpression in H4IIE rat hepatoma cells. Microarray analysis revealed altered expression of genes in metabolism (central carbon and lipid), which correlated with previous flux analysis, and of genes regulated by the glucocorticoid receptor (GR). Oil Red O staining showed that GK overexpression leads to increased fat storage in H4IIE cells. Network component analysis revealed that activities of peroxisome proliferator-activated receptor alpha, GR, and seven other transcription factors were altered by GK overexpression. The increased activity of GR was experimentally verified by quantitative RT-PCR of GR-responsive genes in the presence and absence of the glucocorticoid agonist, dexamethasone. This systems biology approach further emphasizes GK's essential role in central and lipid metabolism and experimentally verifies GK's alternative (moonlighting) function of affecting GR transcription factor activity.
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Affiliation(s)
- Ganesh Sriram
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-7088, USA
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24
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Rahib L, Sriram G, Harada MK, Liao JC, Dipple KM. Transcriptomic and network component analysis of glycerol kinase in skeletal muscle using a mouse model of glycerol kinase deficiency. Mol Genet Metab 2009; 96:106-12. [PMID: 19121967 PMCID: PMC2702540 DOI: 10.1016/j.ymgme.2008.11.163] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 11/16/2008] [Accepted: 11/16/2008] [Indexed: 11/25/2022]
Abstract
Glycerol kinase (GK) is at the interface of fat and carbohydrate metabolism and has been linked to obesity and type 2 diabetes mellitus (T2DM). The purpose of this study was to investigate the role of GK in fat metabolism and insulin signaling in skeletal muscle (an important end organ tissue in T2DM). Microarray analysis determined that there were 525 genes that were differentially expressed (1.2-fold, p value<0.05) between knockout (KO) and wild-type (WT) mice. Quantitative PCR (qPCR) confirmed the differential expression of genes including glycerol kinase (Gyk), phosphatidylinositol 3-kinase regulatory subunit, polypeptide 1 (p85 alpha) (Pik3r1), insulin-like growth factor 1 (Igf1), and growth factor receptor bound protein 2-associated protein 1 (Gab1). Network component analysis demonstrated that transcription factor activities of myogenic differentiation 1 (MYOD), myogenic regulatory factor 5 (MYF5), myogenin (MYOG), nuclear receptor subfamily 4, group A, member 1 (NUR77) are decreased in the Gyk KO whereas the activity of paired box 3 (PAX3) is increased. The activity of MYOD was confirmed using a DNA binding assay. In addition, myoblasts from Gyk KO had less ability to differentiate into myotubes compared to WT myoblasts. These findings support our previous studies in brown adipose tissue and demonstrate that the role of Gyk in muscle is due in part to its non-metabolic (moonlighting) activities.
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MESH Headings
- Animals
- Cell Differentiation
- Cells, Cultured
- Diabetes Mellitus, Type 2/enzymology
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Disease Models, Animal
- Female
- Gene Expression Profiling
- Gene Regulatory Networks
- Glycerol Kinase/deficiency
- Glycerol Kinase/genetics
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/enzymology
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Protein Binding
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Affiliation(s)
- Lola Rahib
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
| | - Ganesh Sriram
- Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA, USA
| | - Melissa K. Harada
- Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
| | - James C. Liao
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA, USA
| | - Katrina M. Dipple
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
- Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Mattel Children’s Hospital at UCLA, University of California, Los Angeles, CA, USA
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25
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Perron P, Brisson D, Santuré M, Blackburn P, Bergeron J, Vohl MC, Després JP, Gaudet D. Apolipoprotein E and lipoprotein lipase gene polymorphisms interaction on the atherogenic combined expression of hypertriglyceridemia and hyperapobetalipoproteinemia phenotypes. J Endocrinol Invest 2007; 30:551-7. [PMID: 17848837 DOI: 10.1007/bf03346348] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The combination of hypertriglyceridemia (hyperTG) and hyperapobetalipoproteinemia (hyperapoB) is associated with an increased coronary artery disease (CAD) risk. Apolipoprotein (apo) E and lipoprotein lipase (LPL) genes are involved in the catabolism of triglycerides (TG)-rich apoB-containing lipoproteins (VLDL). Several apoE and LPL gene variants affecting CAD risk, plasma TG or apoB concentrations have an allelic frequency of >5% in the general population. This study examined the combined effect of frequent apoE and LPL gene polymorphisms on the expression of hyperTG and hyperapoB. ApoE (E2, E3, and E4) and LPL (D9N, N291S, G188E, and P207L) were genotyped and fasting lipid profiles were assessed among 1,441 French-Canadian subjects. Multivariate analyses were performed to estimate the relationship between apoE and LPL gene variants and the risk of hyperTG (TG>1.7 mmol/l) and hyperapoB (apoB>0.9 g/l). Compared to apoE3 carriers, the apoE4 allele significantly increased the risk of expressing the "hyperTG/hyperapoB" phenotype [odds ratio (OR)=1.95; p=0.014]. This risk was significantly exacerbated (OR=4.69; p=0.017) by the presence of frequent deleterious LPL gene variants in this population. The apoE2 allele was negatively associated with hyperTG/hyperapoB (OR=0.49; p=0.002) in the absence of a deleterious LPL gene variant. These results suggest that epistasis is a phenomenon to consider while assessing the CAD risk associated with gene variants or the effect of frequent alleles on high-risk lipid profiles.
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Affiliation(s)
- P Perron
- Department of Medicine, University of Montréal, University of Montréal Community Genomic Medicine Center and Lipid Clinic, Chicoutimi Hospital, Chicoutimi, Québec, Canada G7H5H6
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26
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Rahib L, MacLennan NK, Horvath S, Liao JC, Dipple KM. Glycerol kinase deficiency alters expression of genes involved in lipid metabolism, carbohydrate metabolism, and insulin signaling. Eur J Hum Genet 2007; 15:646-57. [PMID: 17406644 DOI: 10.1038/sj.ejhg.5201801] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Glycerol kinase (GK) is at the interface of fat and carbohydrate metabolism and has been implicated in insulin resistance and type 2 diabetes mellitus. To define GK's role in insulin resistance, we examined gene expression in brown adipose tissue in a glycerol kinase knockout (KO) mouse model using microarray analysis. Global gene expression profiles of KO mice were distinct from wild type with 668 differentially expressed genes. These include genes involved in lipid metabolism, carbohydrate metabolism, insulin signaling, and insulin resistance. Real-time polymerase chain reaction analysis confirmed the differential expression of selected genes involved in lipid and carbohydrate metabolism. PathwayAssist analysis confirmed direct and indirect connections between glycerol kinase and genes in lipid metabolism, carbohydrate metabolism, insulin signaling, and insulin resistance. Network component analysis (NCA) showed that the transcription factors (TFs) PPAR-gamma, SREBP-1, SREBP-2, STAT3, STAT5, SP1, CEBPalpha, CREB, GR and PPAR-alpha have altered activity in the KO mice. NCA also revealed the individual contribution of these TFs on the expression of genes altered in the microarray data. This study elucidates the complex network of glycerol kinase and further confirms a possible role for glycerol kinase deficiency, a simple Mendelian disorder, in insulin resistance, and type 2 diabetes mellitus, a common complex genetic disorder.
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Affiliation(s)
- Lola Rahib
- Biomedical Engineering, Interdepartmental Program, Henry Samueli School of Engineering and Applied Science at UCLA, Los Angeles, CA 90095, USA
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27
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Brisson D, St-Pierre J, Santuré M, Hudson TJ, Després JP, Vohl MC, Gaudet D. Genetic epistasis in the VLDL catabolic pathway is associated with deleterious variations on triglyceridemia in obese subjects. Int J Obes (Lond) 2007; 31:1325-33. [PMID: 17342071 DOI: 10.1038/sj.ijo.0803586] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Abdominal obesity and hypertriglyceridemia (the hypertriglyceridemic-waist phenotype) increase cardiovascular risk. The very low-density lipoprotein (VLDL) is a triglyceride (TG)-rich particle. Frequent variations in the genes coding for enzymes and proteins involved in the VLDL catabolism have already been documented. The epistatic effect of such variants on the risk profile associated with abdominal obesity remains to be elucidated. OBJECTIVE This study aims to assess the effect of combinations of frequent single-nucleotide polymorphisms (SNPs) in the VLDL catabolic pathway on the relation between abdominal obesity and fasting TG. METHOD Only gene variants in the lipoprotein lipase, apolipoprotein (apo) CIII, hepatic lipase and apo E genes known to be frequent in the general population (allele frequency>5%) were included in this study. The presence of selected SNPs was detected by polymerase chain reaction-restriction fragment length polymorphism in a sample of 640 non-diabetic French Canadians at high cardiovascular risk (405 obese, 235 non-obese). RESULTS Carrying more than two frequent gene variants involved in the VLDL catabolic pathway significantly increased the risk of hyperTG (odds ratio of TG>1.7 mmol/l=4.15; P=0.001). This effect was proportional to the number of SNPs and genes involved and was significantly amplified by the presence of abdominal obesity defined on the basis of waist circumference. CONCLUSION When combined with abdominal obesity, epistasis in the VLDL pathway has a deleterious effect on fasting TG and coronary artery disease risk profile according to the TG threshold (1.7 mmol/l) used in medical guidelines for the assessment of the metabolic syndrome and associated risk.
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Affiliation(s)
- D Brisson
- Department of medicine, Université de Montréal, University of Montreal Community Genomic Medicine Center and Lipid Clinic, Chicoutimi Hospital, Chicoutimi, Canada
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Martinez Agosto JA, McCabe ER. Conserved family of glycerol kinase loci in Drosophila melanogaster. Mol Genet Metab 2006; 88:334-45. [PMID: 16545593 PMCID: PMC2807631 DOI: 10.1016/j.ymgme.2006.01.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2006] [Accepted: 01/10/2006] [Indexed: 10/24/2022]
Abstract
Glycerol kinase (GK) is an enzyme that catalyzes the formation of glycerol 3-phosphate from ATP and glycerol, the rate-limiting step in glycerol utilization. We analyzed the genome of the model organism Drosophila melanogaster and identified five GK orthologs, including two loci with sequence homology to the mammalian Xp21 GK protein. Using a combination of sequence analysis and evolutionary comparisons of orthologs between species, we characterized functional domains in the protein required for GK activity. Our findings include additional conserved domains that suggest novel nuclear and mitochondrial functions for glycerol kinase in apoptosis and transcriptional regulation. Investigation of GK function in Drosophila will inform us about the role of this enzyme in development and will provide us with a tool to examine genetic modifiers of human metabolic disorders.
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Affiliation(s)
- Julian A. Martinez Agosto
- Department of Pediatrics, David Geffen School of Medicine at UCLA; and Mattel Children’s Hospital at UCLA, USA
| | - Edward R.B. McCabe
- Department of Pediatrics, David Geffen School of Medicine at UCLA; and Mattel Children’s Hospital at UCLA, USA
- Department of Human Genetics, David Geffen School of Medicine at UCLA; UCLA Molecular Biology Institute; and UCLA Biomedical Engineering Interdepartmental Training Program, USA
- Corresponding author. Fax: +1 310 267 2045. (E.R.B. McCabe)
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Ferrer-Martínez A, Marotta M, Turini M, Macé K, Gómez-Foix AM. Effect of sucrose and saturated-fat diets on mRNA levels of genes limiting muscle fatty acid and glucose supply in rats. Lipids 2006; 41:55-62. [PMID: 16555472 DOI: 10.1007/s11745-006-5070-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In this study, we examined whether the increased availability of lipids in blood resulting from two types of diet manipulation regulated metabolic gene expression in the skeletal muscle of rats. Feeding for 4 wk on an isocaloric-sucrose or a hypercaloric-fat diet increased plasma TAG in the fed condition by increments of 70 and 40%, respectively, and increased fasting insulinemia (approximately 3-fold) compared with a starch diet. The fat diet impaired glucose tolerance and caused obesity, whereas sucrose-fed rats maintained their normal weight. We analyzed the expression of genes that regulate the exogenous FA supply (LPL, FAT/CD36, FATP1), synthesis (ACC1), glucose (GLUT4, GLUT1, HK2, GFAT1, glycogen phosphorylase) or glycerol (glycerol kinase) provision, or substrate choice for oxidation (PDK4) in gastrocnemius and soleus muscles at the end of the glucose tolerance test. LPL, FAT/CD36, FATP1, PDK4, and GLUT4 mRNA as well as glycogen phosphorylase and glycerol kinase activity levels in both muscles were unchanged by the diets. Increased mRNA levels of GLUT1 (1.6- and 2.6-fold, respectively) and GFAT1 (about 1.7-fold) in gastrocnemius, and of ACC1 (about 1.5-fold) in soleus, were found in both the sucrose and fat groups. In the fat group, HK2 mRNA was also higher (1.8-fold) in the gastrocnemius. Both sucrose and saturated-fat diets prompted hyperinsulinemia and hyperlipemia in rats. These metabolic disturbances did not alter the expression of LPL, FAT/CD36, FATP1, PDK4, and GLUT4 genes or glycogen phosphorylase and glycerol kinase activity levels in either analyzed muscle. Instead, they were linked to the coordinated upregulation in gastrocnemius of genes that govern glucose uptake and the hexosamine pathway, namely, GLUT1 and GFAT1, which might contribute to insulin resistance.
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Affiliation(s)
- Andreu Ferrer-Martínez
- Department de Bioquímica i Biologia Molecular, Universitat de Barcelona, E-08028 Barcelona, Spain
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30
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Walter JA, Ewart KV, Short CE, Burton IW, Driedzic WR. Accelerated hepatic glycerol synthesis in rainbow smelt (Osmerus mordax) is fuelled directly by glucose and alanine: a 1H and 13C nuclear magnetic resonance study. ACTA ACUST UNITED AC 2006; 305:480-8. [PMID: 16506225 DOI: 10.1002/jez.a.276] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
At seawater temperatures below 1 degrees C, rainbow smelt (Osmerus mordax) accumulate plasma levels of glycerol up to 400 mM. Aspects of the synthesis of glycerol in liver and its regulation were previously investigated, but the pathways leading to glycerol synthesis remained unconfirmed. Here, we report nuclear magnetic resonance (NMR) studies which elucidate, in more detail, the fuel sources for rapid glycerol synthesis in rainbow smelt. Initial NMR analysis of liver homogenates from fish held at cold (-1 degrees C) temperatures and from fish transferred from 8 degrees C to -1 degrees C showed elevated glycerol, whereas those from fish held at 8 degrees C had far lower glycerol levels. These results confirm a temperature-responsive glycerol synthesis and show that NMR is a suitable approach to investigate the phenomenon. Further studies with fish held at low temperature and injected with labelled L-[2,3-(13)C(2)] alanine or D-[U-(13)C(6)]glucose revealed conversion of both alanine and glucose to glycerol. (13)C spectra showed satellites ((1)J(CC)=41.1 Hz) about the glycerol resonances indicating intact incorporation of a (13)C-(13)C unit in liver glycerol of fish injected with L-[2,3-(13)C(2)]alanine and a (13)C-(13)C-(13)C unit in liver glycerol of fish injected with D[U-(13)C(6)]glucose. Thus, glycerol can be efficiently produced directly from amino acid precursors by glyceroneogenesis, which is an abbreviated gluconeogenesis process leading to glycerol through dihydroxyacetone phosphate (DHAP). Glucose can also be metabolised to glycerol via an abbreviated form of glycolysis that similarly leads to glycerol through DHAP.
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Affiliation(s)
- John A Walter
- NRC Institute for Marine Biosciences, Halifax, NS, Canada B3H 3Z1
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31
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MacLennan NK, Rahib L, Shin C, Fang Z, Horvath S, Dean J, Liao JC, McCabe ERB, Dipple KM. Targeted disruption of glycerol kinase gene in mice: expression analysis in liver shows alterations in network partners related to glycerol kinase activity. Hum Mol Genet 2005; 15:405-15. [PMID: 16368706 DOI: 10.1093/hmg/ddi457] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Glycerol kinase deficiency (GKD) is an X-linked inborn error of metabolism with metabolic and neurological crises. Liver shows the highest level of glycerol kinase (GK) activity in humans and mice. Absence of genotype-phenotype correlations in patients with GKD indicates the involvement of modifier genes, including other network partners. To understand the molecular pathogenesis of GKD, we performed microarray analysis on liver mRNA from neonatal glycerol kinase (Gyk) knockout (KO) and wild-type (WT) mice. Unsupervised learning revealed that the overall gene expression profile of the KO mice was different from that of WT. Real-time PCR confirmed the differences for selected genes. Functional gene enrichment analysis was used to find 56 increased and 37 decreased gene functional categories. PathwayAssist analysis identified changes in gene expression levels of genes involved in organic acid metabolism indicating that GK was part of the same metabolic network which correlates well with the patients with GKD having metabolic acidemia during their episodic crises. Network component analysis (NCA) showed that transcription factors sterol regulatory element-binding protein (SREBP)-1c, carbohydrate response element-binding protein (ChREBP), hepatocyte nuclear factor-4 alpha (HNF-4alpha) and peroxisome proliferative-activated receptor-alpha (PPARalpha) had increased activity in the Gyk KO mice compared with WT mice, whereas SREBP-2 was less active in the Gyk KO mice. These studies show that Gyk deletion causes alterations in expression of genes in several regulatory networks and is the first time NCA has been used to expand on microarray data from a mouse KO model of a human disease.
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Affiliation(s)
- Nicole K MacLennan
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-7088, USA
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Sidransky E. Gaucher disease and parkinsonism. Mol Genet Metab 2005; 84:302-4. [PMID: 15781189 DOI: 10.1016/j.ymgme.2004.11.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Revised: 11/24/2004] [Accepted: 11/30/2004] [Indexed: 10/25/2022]
Affiliation(s)
- Ellen Sidransky
- Section on Molecular Neurogenetics, Clinical Neuroscience Branch, NIMH, and Medical Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892-3708, USA.
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Ferreira C, van Voorst F, Martins A, Neves L, Oliveira R, Kielland-Brandt MC, Lucas C, Brandt A. A member of the sugar transporter family, Stl1p is the glycerol/H+ symporter in Saccharomyces cerevisiae. Mol Biol Cell 2005; 16:2068-76. [PMID: 15703210 PMCID: PMC1073684 DOI: 10.1091/mbc.e04-10-0884] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Revised: 01/13/2005] [Accepted: 01/21/2005] [Indexed: 11/11/2022] Open
Abstract
Glycerol and other polyols are used as osmoprotectants by many organisms. Several yeasts and other fungi can take up glycerol by proton symport. To identify genes involved in active glycerol uptake in Saccharomyces cerevisiae we screened a deletion mutant collection comprising 321 genes encoding proteins with 6 or more predicted transmembrane domains for impaired growth on glycerol medium. Deletion of STL1, which encodes a member of the sugar transporter family, eliminates active glycerol transport. Stl1p is present in the plasma membrane in S. cerevisiae during conditions where glycerol symport is functional. Both the Stl1 protein and the active glycerol transport are subject to glucose-induced inactivation, following identical patterns. Furthermore, the Stl1 protein and the glycerol symporter activity are strongly but transiently induced when cells are subjected to osmotic shock. STL1 was heterologously expressed in Schizosaccharomyces pombe, a yeast that does not contain its own active glycerol transport system. In S. pombe, STL1 conferred the ability to take up glycerol against a concentration gradient in a proton motive force-dependent manner. We conclude that the glycerol proton symporter in S. cerevisiae is encoded by STL1.
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34
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Sidransky E. Gaucher disease: complexity in a "simple" disorder. Mol Genet Metab 2004; 83:6-15. [PMID: 15464415 DOI: 10.1016/j.ymgme.2004.08.015] [Citation(s) in RCA: 271] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Revised: 08/31/2004] [Accepted: 08/31/2004] [Indexed: 12/11/2022]
Abstract
Gaucher disease, the recessively inherited deficiency of the enzyme glucocerebrosidase and the most common sphingolipidosis, has both non-neurological and neuronopathic forms and a continuum of diverse clinical manifestations. Studies of genotype-phenotype correlations reveal significant genotypic heterogeneity among clinically similar patients, and vastly different phenotypes among patients with the same mutations. The region surrounding the glucocerebrosidase gene (GBA) on chromosome 1q is particularly gene-rich, with a highly homologous pseudogene sequence 16 kb downstream. Recombination events within the GBA locus contribute to the etiology of some mutations in Gaucher disease. Studies of patients with Gaucher disease and atypical manifestations, including parkinsonism, myoclonic epilepsy, cardiac involvement and collodion skin, seek to define other genetic or environmental factors contributing to the phenotypes. Recent reports demonstrating an association between Gaucher disease and parkinsonism provide an example of heterozygosity for a Mendelian disorder acting as a risk factor for a complex disease. There are rare patients with Gaucher disease and differing genotypes who develop early onset, treatment-refractory parkinsonism. Neuropathology in a group of these patients showed alpha-synuclein-reactive Lewy bodies in brain regions specifically associated with Gaucher disease. Family studies of these probands suggested that the incidence of parkinsonism might be more frequent in obligate heterozygotes. In a complementary finding, the examination of GBA in autopsy samples from individuals with sporadic Parkinson disease identified alterations in the GBA sequence in 14% of the cohort. These studies provide evidence that altered glucocerebrosidase may contribute to a vulnerability to parkinsonism. Moreover, this research demonstrates how insights from rare, single gene disorders like Gaucher disease can provide a window into the etiology of more common, multifactorial genetic diseases.
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Affiliation(s)
- Ellen Sidransky
- Section on Molecular Neurogenetics, NIMH 35 Convent Drive MSC 3708, 1A-213, Bethesda, MD 20892-3708, USA.
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35
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Brouillette C, Bossé Y, Pérusse L, Gaudet D, Vohl MC. Effect of liver fatty acid binding protein (FABP) T94A missense mutation on plasma lipoprotein responsiveness to treatment with fenofibrate. J Hum Genet 2004; 49:424-432. [PMID: 15249972 DOI: 10.1007/s10038-004-0171-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Accepted: 05/06/2004] [Indexed: 11/27/2022]
Abstract
Fenofibrate, a peroxisome proliferated activated receptor alpha (PPARalpha) agonist, has been shown to decrease plasma triglyceride (TG) and increase plasma high-density lipoprotein (HDL) cholesterol levels despite a large interindividual variation in the response. Fenofibrate-activated PPARalpha binds to a DNA sequence element termed PPAR response element (PPRE) present in regulatory regions of target genes. A PPRE has been identified in the proximal 5' flanking region of the gene encoding the liver fatty acid binding protein (LFABP). LFABP is a small cytosolic protein of 14 kDa present in the liver and the intestine and is a member of the superfamily of the fatty acid binding proteins (FABPs). FABPs play a role in the solubilization of long-chain fatty acids (LCFAs) and their CoA-ester to various intracellular organelles. FABPs serves as intracellular acceptors of LCFAs, and they may also have an impact in ligand-dependent transactivation of PPARs in trafficking LCFAs to the nucleus. Since PPARs are known to regulate the transcription of many genes involved in lipid metabolism, the importance of LFABP in fatty acid uptake has to be considered. The aim of this study was to verify whether genetic variations in the LFABP gene may impact on plasma lipoprotein/lipid levels in the fasting state as well as on the response to a lipid-lowering therapy with fenofibrate on plasma lipids and obesity variables. We also wanted to verify whether the presence of the PPARalpha L162V mutation interacts with genetic variants in LFABP gene. To achieve this goal, we first determined the genomic structure of the human LFABP gene and then designed intronic primers to sequence the coding regions, all exon-intron splicing boundaries, and the promoter region of the gene in 24 patients showing divergent plasma lipoprotein/lipid response to fenofibrate. Sequence analysis revealed the presence of a T94A missense mutation in exon 3. Interspecies comparison revealed that threonine 94 is conserved among species. We subsequently screened another sample of 130 French Canadian subjects treated with fenofibrate for the presence of the LFABP T94A mutation. Carriers of the A94 allele were at increased risk to exhibit plasma TG levels above 2.00 mmol/l after treatment with fenofibrate [2.75 (1.03-7.34); OR 95% confidence interval (CI)]. In addition, carriers of the A94 allele were characterized by higher baseline plasma-free fatty acid levels (FFA) ( p=0.01) and by a lower body mass index (BMI) ( p=0.05) and waist circumference ( p=0.005) than T94 homozygotes. Moreover, PPARalpha L162V and LFABP T94A showed to have a synergistic effect on BMI ( p interaction = 0.03). These results suggest that the LFABP T94A missense mutation could influence obesity indices as well as the risk to exhibit residual hypertriglyceridmia following a lipid-lowering therapy with fenofibrate.
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Affiliation(s)
- Charles Brouillette
- Lipid Research Center, CHUL Research Center, 2705 Laurier Blvd, TR93, Sainte-Foy, QC, Canada, G1V 4G2
- Department of Food Science and Nutrition, Laval University, Laval, QC, Canada
| | - Yohan Bossé
- Lipid Research Center, CHUL Research Center, 2705 Laurier Blvd, TR93, Sainte-Foy, QC, Canada, G1V 4G2
- Department of Food Science and Nutrition, Laval University, Laval, QC, Canada
| | - Louis Pérusse
- Division of Kinesiology, Department of Social and Preventive Medicine, Laval University, Laval, QC, Canada
| | - Daniel Gaudet
- Dyslipidemia, Diabetes and Atherosclerosis Group, Complexe Hospitalier de la Sagamie, Saguenay, QC, Canada
| | - Marie-Claude Vohl
- Lipid Research Center, CHUL Research Center, 2705 Laurier Blvd, TR93, Sainte-Foy, QC, Canada, G1V 4G2.
- Department of Food Science and Nutrition, Laval University, Laval, QC, Canada.
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Stepanian SV, Huyn ST, McCabe ERB, Dipple KM. Characterization of the human glycerol kinase promoter: identification of a functional HNF-4alpha binding site and evidence for transcriptional activation. Mol Genet Metab 2003; 80:412-8. [PMID: 14654354 DOI: 10.1016/j.ymgme.2003.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Glycerol kinase (GK) is an enzyme at the interface of carbohydrate and fat metabolism. Mutations in the GK gene result in a rare inborn error of metabolism, GK deficiency (GKD), and at least one of these mutations (N288D) is associated with insulin resistance and diabetes mellitus. In an attempt to identify potential modifiers of the GKD phenotype, and to elucidate better the relationship between GKD and diabetes mellitus, we investigated the GK promoter. We examined the GK promoter using in silico methods, transient transfections of GK promoter-luciferase constructs in HepG2 hepatocellular carcinoma cells, and gel shift assays using liver nuclear extracts. We determined that the first 100 bp of the GK 5(') upstream region was sufficient for basal levels of transcription and that there was a functional HNF-4alpha binding site in the first 500 bp of the 5(') upstream region that was important for increased levels of GK expression in vitro. The involvement of both GK and HNF-4alpha in the etiology of diabetes mellitus is intriguing, and we speculate that HNF-4alpha represents a potential modifier of the GKD phenotype.
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Affiliation(s)
- Sevan V Stepanian
- Department of Pediatrics, David Geffen School of Medicine at UCLA and Mattel Children's Hospital at UCLA, Los Angeles, CA, USA
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37
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Pausova Z, Sedova L, Berube J, Hamet P, Tremblay J, Dumont M, Gaudet D, Pravenec M, Kren V, Kunes J. Segment of rat chromosome 20 regulates diet-induced augmentations in adiposity, glucose intolerance, and blood pressure. Hypertension 2003; 41:1047-55. [PMID: 12654711 DOI: 10.1161/01.hyp.0000064347.49341.0b] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Previous linkage and association studies have suggested that a region of human chromosome 6 containing the tumor necrosis factor (TNF)-alpha gene is involved in the pathogenesis of obesity and obesity-associated hypertension. The aim of the present investigation was to establish whether a segment of rat chromosome 20 (RNO20), which also contains the TNF-alpha gene, determines diet-induced changes in adiposity and blood pressure (BP). The results showed that a transfer of the RNO20 segment from the normotensive Brown Norway (BN) rat onto the background of the spontaneously hypertensive rat (SHR) is associated with a significantly greater increase in adiposity, glucose intolerance, circulating leptin levels, and BP during 12-week, high-fat-diet feeding. In contrast, the transfer is not associated with significant changes in these variables during 12-week, normal-diet feeding. In addition, sequencing of the TNF-alpha gene revealed differences between SHR and BN in the 5'- and 3'-regulatory regions of the gene. Subsequent analyses of TNF-alpha gene expression in fat, muscle, and liver, however, did not provide support for the functional involvement of these differences. In summary, the investigated RNO20 segment contains 1 or more gene variants that affect adiposity, glucose tolerance, serum leptin levels, and BP, but only when the animals are exposed to a particular environment, ie, high-fat-diet feeding. Further studies are needed to identify genes mediating these effects. Considering current changes in our lifestyle involving an increased calorie and fat intake, we believe that gene-environment interactions, such as those described here, play an important role in the current epidemic of obesity and obesity-associated hypertension.
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Affiliation(s)
- Zdenka Pausova
- Laboratory of Functional Genomics, Centre de recherche, CHUM Hôtel-Die, 3850 St Urbain St, Montréal, Québec H2W 1T7, Canada.
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Hellerud C, Burlina A, Gabelli C, Ellis JR, Nyholm PG, Lindstedt S. Glycerol metabolism and the determination of triglycerides--clinical, biochemical and molecular findings in six subjects. Clin Chem Lab Med 2003; 41:46-55. [PMID: 12636049 DOI: 10.1515/cclm.2003.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Recent recommendations in the National Cholesterol Education Program Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults (ATPIII) are expected to increase the number of triglyceride (TG) determinations and consequently the risk of misinterpretation of "non-blanked" results with co-determination of free glycerol. Glycerol-kinase deficiency (GKD) is one cause of falsely elevated TG results. The natural history of isolated GKD with symptom-free cases and cases with e.g. severe episodes of hypoglycemia and/or ketoacidosis challenges the laboratories to identify cases of GKD and family members at risk. "Blanked" methods reporting both glycerol and TG concentration are therefore desirable. Molecular studies of the glycerol kinase (GK) and DAX1 genes were performed on four cases of "persistent hypertriglyceridemia" found in an Italian population and on two pediatric cases with high serum glycerol concentration. Two new missense mutations were found (C358Y, T961). Molecular modeling on GK from E. coli, indicate that these mutations are located in parts of the enzyme important for enzyme formation or activity. One splice-site mutation, (IVS9A-1G>A), was found in two brothers. Splice-junction analysis indicates that it destroys the splice site and results in a mixture of mRNA. Deletion of the GK and DAX1 genes was found in one child with symptoms of adrenal failure. A female with glycerolemia and glyceroluria had normal GK activity but possibly slightly decreased ability to oxidize glycerol.
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Affiliation(s)
- Christina Hellerud
- Department of Clinical Chemistry, Sahlgrenska University Hospital, Göteborg University, Gothenburg, Sweden.
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Guan HP, Li Y, Jensen MV, Newgard CB, Steppan CM, Lazar MA. A futile metabolic cycle activated in adipocytes by antidiabetic agents. Nat Med 2002; 8:1122-8. [PMID: 12357248 DOI: 10.1038/nm780] [Citation(s) in RCA: 285] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2002] [Accepted: 08/28/2002] [Indexed: 12/18/2022]
Abstract
Thiazolidinediones (TZDs) are effective therapies for type 2 diabetes, which has reached epidemic proportions in industrialized societies. TZD treatment reduces circulating free fatty acids (FFAs), which oppose insulin actions in skeletal muscle and other insulin target tissues. Here we report that TZDs, acting as ligands for the nuclear receptor peroxisome proliferator-activated receptor (PPAR)-gamma, markedly induce adipocyte glycerol kinase (GyK) gene expression. This is surprising, as standard textbooks indicate that adipocytes lack GyK and thereby avoid futile cycles of triglyceride breakdown and resynthesis from glycerol and FFAs. By inducing GyK, TZDs markedly stimulate glycerol incorporation into triglyceride and reduce FFA secretion from adipocytes. The 'futile' fuel cycle resulting from expression of GyK in adipocytes is thus a novel mechanism contributing to reduced FFA levels and perhaps insulin sensitization by antidiabetic therapies.
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Affiliation(s)
- Hong-Ping Guan
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and The Penn Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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40
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Brisson D, Ledoux K, Bossé Y, St-Pierre J, Julien P, Perron P, Hudson TJ, Vohl MC, Gaudet D. Effect of apolipoprotein E, peroxisome proliferator-activated receptor alpha and lipoprotein lipase gene mutations on the ability of fenofibrate to improve lipid profiles and reach clinical guideline targets among hypertriglyceridemic patients. PHARMACOGENETICS 2002; 12:313-20. [PMID: 12042669 DOI: 10.1097/00008571-200206000-00007] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Fenofibrate is a peroxisome proliferator-activated receptor alpha (PPARalpha) agonist which regulates the transcription of genes encoding proteins involved in triglyceride (TG)-rich lipoproteins and lipoprotein lipase (LPL) metabolism. The aim of the present study was to investigate the relation between TG-related parameters considered in different clinical guidelines used in industrialized countries for the management of lipid disorders (namely fasting plasma TG, high density-lipoprotein cholesterol (HDL-C), non-HDL-C concentrations and total-C/HDL-C ratio) and the presence of LPL-null (P207L), LPL-defective (D9N), PPARalpha -L162V, apolipoprotein (apo) E and PPARgamma-P12A gene mutations, in a sample of 292 hypertriglyceridemic subjects treated with fenofibrate for 3 months. Although fenofibrate induced a decrease in plasma TG level and an increase in HDL-C level in all studied genotypes, mutation-specific differences were observed. After adjustment for age, gender, body mass index and the presence of apo E2 genotype, the LPL-P207L mutation was associated with residual post-treatment hypertriglyceridemia [TG > 2.0 mmol/l, odds ratio (OR) = 3.07, P = 0.005] and total-C/HDL-C ratio > 5 (OR = 2.68; P = 0.03). This effect was significantly related to higher plasma TG concentrations at baseline among carriers of a LPL-null mutation. Compared to apo E3 and E4 variants, the apo E2 allele was associated with a better response to fenofibrate on all lipid parameter, especially among PPARalpha -L162V carriers, whereas the simultaneous presence of apo E2 and PPARalpha -L162V tended to improve fenofibrate response among LPL-P207L heterozygotes. Finally, the LPL-D9N and PPARgamma -P12A mutations did not affect fenofibrate lipid-lowering action. This study suggests that frequent genetic variations in genes encoding proteins involved in TG-rich lipoprotein metabolism could modulate the response to fenofibrate treatment, as defined in clinical guidelines.
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Affiliation(s)
- Diane Brisson
- Community Genomic Medicine Centre, University of Montreal, Chicoutimi Hospital, Québec, Canada
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Brisson D, Vohl MC, St-Pierre J, Hudson TJ, Gaudet D. Glycerol: a neglected variable in metabolic processes? Bioessays 2001; 23:534-42. [PMID: 11385633 DOI: 10.1002/bies.1073] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Glycerol is a small and simple molecule produced in the breakdown of glucose, proteins, pyruvate, triacylglycerols and other glycerolipid, as well as release from dietary fats. An increasing number of observations show that glycerol is probably involved in a surprising variety of physiopathologic mechanisms. Glycerol has long been known to play fundamental roles in several vital physiological processes, in prokaryotes and eukaryotes, and is an important intermediate of energy metabolism. Despite some differences in the details of their operation, many of these mechanisms have been preserved throughout evolution, demonstrating their fundamental importance. In particular, glycerol can control osmotic activity and crystal formation and then act as a cryoprotective agent. Furthermore, its properties make it useful in numerous industrial, therapeutic and diagnostic applications. Few studies have focussed directly on glycerol, however, and while its metabolism is increasingly well documented, much of the details remain unknown. Considering the importance of glycerol in multiple vital physiological processes, its study could help unlock important physiopathological mechanisms.
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Affiliation(s)
- D Brisson
- Lipid Research Group, Chicoutimi Hospital, Quebec, Canada
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St-Pierre J, Vohl MC, Brisson D, Perron P, Després JP, Hudson TJ, Gaudet D. A sequence variation in the mitochondrial glycerol-3-phosphate dehydrogenase gene is associated with increased plasma glycerol and free fatty acid concentrations among French Canadians. Mol Genet Metab 2001; 72:209-17. [PMID: 11243726 DOI: 10.1006/mgme.2000.3144] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
FAD-dependent glycerol-3-phosphate dehydrogenase (mGPD) enzyme is located in the mitochondrial inner membrane where it catalyzes irreversible oxidation reactions. Type 2 diabetes mellitus (DM) is a multifactorial disorder associated with physiological abnormalities in the glycerol and free fatty acids (FFA) metabolic pathways. In the present study, we have evaluated the association among the mGPD H264R sequence variation and postabsorptive plasma FFA and glycerol concentrations in a sample of French Canadians with and without type 2 DM. A sample of 81 recently diagnosed type 2 DM and 318 nondiabetic, nonobese, normotriglyceridemic French Canadians were screened for the presence of the mGPD H264R genetic variant using a PCR-RFLP-based method. The 318 nondiabetic subjects were free of known type 2 DM covariates (fasting glucose <7.0 mmol/L, body mass index <29 kg/m(2), fasting glycerol <2.0 mmol/L and absence of the N288D sequence variation in the glycerol kinase gene, fasting triglyceride <2.5 mmol/L). The association of mGPD H264R sequence variation with plasma FFA and glycerol concentrations was assessed in different regression models. Among non-DM individuals, the R allele (HR and RR genotypes) was associated with increased plasma FFA and glycerol concentrations (P < 0.05). However, the mean plasma FFA and glycerol concentrations were not affected by the H264R genotype in the type 2 DM sample. Overall, mean plasma FFA concentrations in non-DM RR homozygotes reached values that were similar to those achieved in patients with type 2 diabetes (0.87 +/- 0.63 vs 0.90 +/- 0.48 mmol/L). After controlling for age, gender, body mass index, fasting glucose, and fasting triglyceride concentrations, the relative odds of having fasting plasma FFA levels above the 90th percentile (0.9 mmol/L) in the absence of DM was increased by twofold in H264R heterozygotes (P = 0.04) and fourfold among R264 homozygotes (P = 0.009) compared to noncarriers. In the absence of DM, the mGPD R allele was also associated with higher plasma glycerol concentrations (P < 0.05). Results in non-DM individuals suggest that the mGPD R allele is associated with DM intermediate phenotypes. The absence of a relation between mGPD genotype and DM is in accordance with the view that DM is a complex phenotype in which increased plasma FFA or glycerol concentrations result from metabolic alterations which might obscure the effect of the mGPD polymorphism.
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Affiliation(s)
- J St-Pierre
- Dyslipidemia, Diabetes and Atherosclerosis Research Group, Chicoutimi Hospital, Quebec, Canada
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