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Wong KHY, Levy-Sakin M, Ma W, Gonzaludo N, Mak ACY, Vaka D, Poon A, Chu C, Lao R, Balamir M, Grenville Z, Wong N, Kane JP, Kwok PY, Malloy MJ, Pullinger CR. Three patients with homozygous familial hypercholesterolemia: Genomic sequencing and kindred analysis. Mol Genet Genomic Med 2019; 7:e1007. [PMID: 31617323 PMCID: PMC6900368 DOI: 10.1002/mgg3.1007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/18/2019] [Accepted: 09/25/2019] [Indexed: 12/21/2022] Open
Abstract
Background Homozygous Familial Hypercholesterolemia (HoFH) is an inherited recessive condition associated with extremely high levels of low‐density lipoprotein (LDL) cholesterol in affected individuals. It is usually caused by homozygous or compound heterozygous functional mutations in the LDL receptor (LDLR). A number of mutations causing FH have been reported in literature and such genetic heterogeneity presents great challenges for disease diagnosis. Objective We aim to determine the likely genetic defects responsible for three cases of pediatric HoFH in two kindreds. Methods We applied whole exome sequencing (WES) on the two probands to determine the likely functional variants among candidate FH genes. We additionally applied 10x Genomics (10xG) Linked‐Reads whole genome sequencing (WGS) on one of the kindreds to identify potentially deleterious structural variants (SVs) underlying HoFH. A PCR‐based screening assay was also established to detect the LDLR structural variant in a cohort of 641 patients with elevated LDL. Results In the Caucasian kindred, the FH homozygosity can be attributed to two compound heterozygous LDLR damaging variants, an exon 12 p.G592E missense mutation and a novel 3kb exon 1 deletion. By analyzing the 10xG phased data, we ascertained that this deletion allele was most likely to have originated from a Russian ancestor. In the Mexican kindred, the strikingly elevated LDL cholesterol level can be attributed to a homozygous frameshift LDLR variant p.E113fs. Conclusions While the application of WES can provide a cost‐effective way of identifying the genetic causes of FH, it often lacks sensitivity for detecting structural variants. Our finding of the LDLR exon 1 deletion highlights the broader utility of Linked‐Read WGS in detecting SVs in the clinical setting, especially when HoFH patients remain undiagnosed after WES.
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Affiliation(s)
- Karen H Y Wong
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Michal Levy-Sakin
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Walfred Ma
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Nina Gonzaludo
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Angel C Y Mak
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA.,Lung Biology Center, University of California, San Francisco, CA, USA
| | - Dedeepya Vaka
- Institute for Human Genetics, University of California, San Francisco, CA, USA
| | - Annie Poon
- Institute for Human Genetics, University of California, San Francisco, CA, USA
| | - Catherine Chu
- Institute for Human Genetics, University of California, San Francisco, CA, USA
| | - Richard Lao
- Institute for Human Genetics, University of California, San Francisco, CA, USA
| | - Melek Balamir
- Department of Internal Medicine, Istanbul University, Istanbul, Turkey
| | - Zoe Grenville
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Nicolas Wong
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - John P Kane
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA.,Department of Medicine, University of California, San Francisco, CA, USA.,Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| | - Pui-Yan Kwok
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA.,Institute for Human Genetics, University of California, San Francisco, CA, USA.,Department of Dermatology, University of California, San Francisco, CA, USA
| | - Mary J Malloy
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA.,Department of Medicine, University of California, San Francisco, CA, USA.,Department of Pediatrics, University of California, San Francisco, CA, USA
| | - Clive R Pullinger
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA.,Department of Physiological Nursing, University of California, San Francisco, CA, USA
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Mao G, Songdej N, Voora D, Goldfinger LE, Del Carpio-Cano FE, Myers RA, Rao AK. Transcription Factor RUNX1 Regulates Platelet PCTP (Phosphatidylcholine Transfer Protein): Implications for Cardiovascular Events: Differential Effects of RUNX1 Variants. Circulation 2017; 136:927-939. [PMID: 28676520 DOI: 10.1161/circulationaha.116.023711] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 06/16/2017] [Indexed: 02/02/2023]
Abstract
BACKGROUND PCTP (phosphatidylcholine transfer protein) regulates the intermembrane transfer of phosphatidylcholine. Higher platelet PCTP expression is associated with increased platelet responses on activation of protease-activated receptor 4 thrombin receptors noted in black subjects compared with white subjects. Little is known about the regulation of platelet PCTP. Haplodeficiency of RUNX1, a major hematopoietic transcription factor, is associated with thrombocytopenia and impaired platelet responses on activation. Platelet expression profiling of a patient with a RUNX1 loss-of-function mutation revealed a 10-fold downregulation of the PCTP gene compared with healthy controls. METHODS We pursued the hypothesis that PCTP is regulated by RUNX1 and that PCTP expression is correlated with cardiovascular events. We studied RUNX1 binding to the PCTP promoter using DNA-protein binding studies and human erythroleukemia cells and promoter activity using luciferase reporter studies. We assessed the relationship between RUNX1 and PCTP in peripheral blood RNA and PCTP and death or myocardial infarction in 2 separate patient cohorts (587 total patients) with cardiovascular disease. RESULTS Platelet PCTP protein in the patient was reduced by ≈50%. DNA-protein binding studies showed RUNX1 binding to consensus sites in ≈1 kB of PCTP promoter. PCTP expression was increased with RUNX1 overexpression and reduced with RUNX1 knockdown in human erythroleukemia cells, indicating that PCTP is regulated by RUNX1. Studies in 2 cohorts of patients showed that RUNX1 expression in blood correlated with PCTP gene expression; PCTP expression was higher in black compared with white subjects and was associated with future death/myocardial infarction after adjustment for age, sex, and race (odds ratio, 2.05; 95% confidence interval 1.6-2.7; P<0.0001). RUNX1 expression is known to initiate at 2 alternative promoters, a distal P1 and a proximal P2 promoter. In patient cohorts, there were differential effects of RUNX1 isoforms on PCTP expression with a negative correlation in blood between RUNX1 expressed from the P1 promoter and PCTP expression. CONCLUSIONS PCTP is a direct transcriptional target of RUNX1. PCTP expression is associated with death/myocardial infarction in patients with cardiovascular disease. RUNX1 regulation of PCTP may play a role in the pathogenesis of platelet-mediated cardiovascular events.
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Affiliation(s)
- Guangfen Mao
- From Sol Sherry Thrombosis Research Center (G.M., N.S., F.E.D.C.-C., L.E.G., A.K.R.), Hematology Section, Department of Medicine (N.S., A.K.R.), and Department of Anatomy and Cell Biology (L.E.G.), Lewis Katz School of Medicine at Temple University, Philadelphia, PA; and Duke Center for Applied Genomics and Precision Medicine, Department of Medicine, Duke University, Durham, NC (D.V., R.A.M.)
| | - Natthapol Songdej
- From Sol Sherry Thrombosis Research Center (G.M., N.S., F.E.D.C.-C., L.E.G., A.K.R.), Hematology Section, Department of Medicine (N.S., A.K.R.), and Department of Anatomy and Cell Biology (L.E.G.), Lewis Katz School of Medicine at Temple University, Philadelphia, PA; and Duke Center for Applied Genomics and Precision Medicine, Department of Medicine, Duke University, Durham, NC (D.V., R.A.M.)
| | - Deepak Voora
- From Sol Sherry Thrombosis Research Center (G.M., N.S., F.E.D.C.-C., L.E.G., A.K.R.), Hematology Section, Department of Medicine (N.S., A.K.R.), and Department of Anatomy and Cell Biology (L.E.G.), Lewis Katz School of Medicine at Temple University, Philadelphia, PA; and Duke Center for Applied Genomics and Precision Medicine, Department of Medicine, Duke University, Durham, NC (D.V., R.A.M.)
| | - Lawrence E Goldfinger
- From Sol Sherry Thrombosis Research Center (G.M., N.S., F.E.D.C.-C., L.E.G., A.K.R.), Hematology Section, Department of Medicine (N.S., A.K.R.), and Department of Anatomy and Cell Biology (L.E.G.), Lewis Katz School of Medicine at Temple University, Philadelphia, PA; and Duke Center for Applied Genomics and Precision Medicine, Department of Medicine, Duke University, Durham, NC (D.V., R.A.M.)
| | - Fabiola E Del Carpio-Cano
- From Sol Sherry Thrombosis Research Center (G.M., N.S., F.E.D.C.-C., L.E.G., A.K.R.), Hematology Section, Department of Medicine (N.S., A.K.R.), and Department of Anatomy and Cell Biology (L.E.G.), Lewis Katz School of Medicine at Temple University, Philadelphia, PA; and Duke Center for Applied Genomics and Precision Medicine, Department of Medicine, Duke University, Durham, NC (D.V., R.A.M.)
| | - Rachel A Myers
- From Sol Sherry Thrombosis Research Center (G.M., N.S., F.E.D.C.-C., L.E.G., A.K.R.), Hematology Section, Department of Medicine (N.S., A.K.R.), and Department of Anatomy and Cell Biology (L.E.G.), Lewis Katz School of Medicine at Temple University, Philadelphia, PA; and Duke Center for Applied Genomics and Precision Medicine, Department of Medicine, Duke University, Durham, NC (D.V., R.A.M.)
| | - A Koneti Rao
- From Sol Sherry Thrombosis Research Center (G.M., N.S., F.E.D.C.-C., L.E.G., A.K.R.), Hematology Section, Department of Medicine (N.S., A.K.R.), and Department of Anatomy and Cell Biology (L.E.G.), Lewis Katz School of Medicine at Temple University, Philadelphia, PA; and Duke Center for Applied Genomics and Precision Medicine, Department of Medicine, Duke University, Durham, NC (D.V., R.A.M.).
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Ersoy BA, Tarun A, D'Aquino K, Hancer NJ, Ukomadu C, White MF, Michel T, Manning BD, Cohen DE. Phosphatidylcholine transfer protein interacts with thioesterase superfamily member 2 to attenuate insulin signaling. Sci Signal 2013; 6:ra64. [PMID: 23901139 DOI: 10.1126/scisignal.2004111] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Phosphatidylcholine transfer protein (PC-TP) is a phospholipid-binding protein that is enriched in liver and that interacts with thioesterase superfamily member 2 (THEM2). Mice lacking either protein exhibit improved hepatic glucose homeostasis and are resistant to diet-induced diabetes. Insulin receptor substrate 2 (IRS2) and mammalian target of rapamycin complex 1 (mTORC1) are key effectors of insulin signaling, which is attenuated in diabetes. We found that PC-TP inhibited IRS2, as evidenced by insulin-independent IRS2 activation after knockdown, genetic ablation, or chemical inhibition of PC-TP. In addition, IRS2 was activated after knockdown of THEM2, providing support for a role for the interaction of PC-TP with THEM2 in suppressing insulin signaling. Additionally, we showed that PC-TP bound to tuberous sclerosis complex 2 (TSC2) and stabilized the components of the TSC1-TSC2 complex, which functions to inhibit mTORC1. Preventing phosphatidylcholine from binding to PC-TP disrupted interactions of PC-TP with THEM2 and TSC2, and disruption of the PC-TP-THEM2 complex was associated with increased activation of both IRS2 and mTORC1. In livers of mice with genetic ablation of PC-TP or that had been treated with a PC-TP inhibitor, steady-state amounts of IRS2 were increased, whereas those of TSC2 were decreased. These findings reveal a phospholipid-dependent mechanism that suppresses insulin signaling downstream of its receptor.
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Affiliation(s)
- Baran A Ersoy
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Shishova EY, Stoll JM, Ersoy BA, Shrestha S, Scapa EF, Li Y, Niepel MW, Su Y, Jelicks LA, Stahl GL, Glicksman M, Gutierrez-Juarez R, Cuny GD, Cohen DE. Genetic ablation or chemical inhibition of phosphatidylcholine transfer protein attenuates diet-induced hepatic glucose production. Hepatology 2011; 54:664-74. [PMID: 21538437 PMCID: PMC3144994 DOI: 10.1002/hep.24393] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 04/20/2011] [Indexed: 12/07/2022]
Abstract
UNLABELLED Phosphatidylcholine transfer protein (PC-TP, synonym StARD2) is a highly specific intracellular lipid binding protein that is enriched in liver. Coding region polymorphisms in both humans and mice appear to confer protection against measures of insulin resistance. The current study was designed to test the hypotheses that Pctp-/- mice are protected against diet-induced increases in hepatic glucose production and that small molecule inhibition of PC-TP recapitulates this phenotype. Pctp-/- and wildtype mice were subjected to high-fat feeding and rates of hepatic glucose production and glucose clearance were quantified by hyperinsulinemic euglycemic clamp studies and pyruvate tolerance tests. These studies revealed that high-fat diet-induced increases in hepatic glucose production were markedly attenuated in Pctp-/- mice. Small molecule inhibitors of PC-TP were synthesized and their potencies, as well as mechanism of inhibition, were characterized in vitro. An optimized inhibitor was administered to high-fat-fed mice and used to explore effects on insulin signaling in cell culture systems. Small molecule inhibitors bound PC-TP, displaced phosphatidylcholines from the lipid binding site, and increased the thermal stability of the protein. Administration of the optimized inhibitor to wildtype mice attenuated hepatic glucose production associated with high-fat feeding, but had no activity in Pctp-/- mice. Indicative of a mechanism for reducing glucose intolerance that is distinct from commonly utilized insulin-sensitizing agents, the inhibitor promoted insulin-independent phosphorylation of key insulin signaling molecules. CONCLUSION These findings suggest PC-TP inhibition as a novel therapeutic strategy in the management of hepatic insulin resistance.
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Affiliation(s)
- Ekaterina Y. Shishova
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Janis M. Stoll
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Baran A. Ersoy
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Sudeep Shrestha
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Erez F. Scapa
- Gastroenterology Department, Sourasky Medical Center, Tel-Aviv, Israel
| | - Yingxia Li
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Michele W. Niepel
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Ya Su
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, 10461, USA
| | - Linda A. Jelicks
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York, 10461, USA
| | - Gregory L. Stahl
- Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Marcie Glicksman
- Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Roger Gutierrez-Juarez
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, 10461, USA
| | - Gregory D Cuny
- Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - David E. Cohen
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
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Bouchard-Mercier A, Godin G, Lamarche B, Pérusse L, Vohl MC. Effects of peroxisome proliferator-activated receptors, dietary fat intakes and gene-diet interactions on peak particle diameters of low-density lipoproteins. JOURNAL OF NUTRIGENETICS AND NUTRIGENOMICS 2011; 4:36-48. [PMID: 21487230 DOI: 10.1159/000324531] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 01/20/2011] [Indexed: 01/03/2023]
Abstract
UNLABELLED The risk of cardiovascular diseases (CVDs) is modulated by gene-diet interactions. The objective of this study was to examine whether gene-diet interactions affect peak particle diameters (PPD) of low-density lipoprotein (LDL). METHODS The study included 674 participants. A food frequency questionnaire was administered to obtain dietary information. LDL-PPD was determined by non-denaturing 2-16% polyacrylamide gradient gel electrophoresis. Peroxisome proliferator-activated receptor (PPAR) gene polymorphisms PPARα L162V (rs1800206), PPARγ P12A (rs1801282) and PPARδ -87T→C (rs2016520) were determined by PCR-RFLP. RESULTS Among carriers of thePPARα L162V polymorphism, gene-diet interaction effects on LDL-PPD were observed with saturated fat (p=0.0005) and total dietary fat (p=0.006). Among PPARα V162 carriers, subjects with higher saturated fat intakes had smaller LDL-PPD than those with lower intakes (254.23±2.74 vs. 256.21±2.61 Å, respectively, p=0.007). Among subjects homozygous for the PPARα L162 allele, those with higher saturated fat intakes had larger LDL-PPD than those with lower saturated fat intakes (255.86±2.66 vs. 255.05±2.65 Å, respectively, p=0.01). Gene-diet interactions were also found for PPARγ P12A polymorphism with saturated fat intake (p=0.04) and for PPARδ -87T→C with the polyunsaturated/saturated fat ratio (p=0.0013). CONCLUSIONS These results stress that dietary factors should be included in studies determining the effect of different polymorphisms on CVD risk factors.
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Affiliation(s)
- Annie Bouchard-Mercier
- Institute of Nutraceuticals and Functional Foods, Department of Food Science and Nutrition, Faculty of Nursing, Laval University, Québec, Canada
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Dolley G, Boisclair M, Lamarche B, Després J, Bouchard C, Pérusse L, Vohl M. Interactions between Dietary Fat Intake and FASN Genetic Variation Influence LDL Peak Particle Diameter. JOURNAL OF NUTRIGENETICS AND NUTRIGENOMICS 2011; 4:137-45. [DOI: 10.1159/000327778] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 03/21/2011] [Indexed: 12/21/2022]
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Kang HW, Wei J, Cohen DE. PC-TP/StARD2: Of membranes and metabolism. Trends Endocrinol Metab 2010; 21:449-56. [PMID: 20338778 PMCID: PMC2897958 DOI: 10.1016/j.tem.2010.02.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 02/03/2010] [Accepted: 02/04/2010] [Indexed: 11/25/2022]
Abstract
Phosphatidylcholine transfer protein (PC-TP, synonym StARD2) binds phosphatidylcholines, and catalyzes their intermembrane transfer and exchange in vitro. The structure of PC-TP comprises a hydrophobic pocket and a well-defined head group binding site, and its gene expression is regulated by peroxisome proliferator activated receptor-alpha. Recent studies have revealed key regulatory roles for PC-TP in lipid and glucose metabolism. Notably, Pctp(-/-) mice are sensitized to the action of insulin, and exhibit more efficient brown fat-mediated thermogenesis. PC-TP appears to limit access of fatty acids to mitochondria by stimulating the activity of thioesterase superfamily member 2, a newly characterized long-chain fatty acyl-coenzyme A thioesterase. Because PC-TP discriminates between phosphatidylcholines within lipid bilayers, it might function as a sensor that links metabolic regulation to membrane composition.
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Affiliation(s)
- Hye Won Kang
- Department of Medicine, Division of Gastroenterology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Dolley G, Lamarche B, Després JP, Bouchard C, Pérusse L, Vohl MC. Phosphoinositide cycle gene polymorphisms affect the plasma lipid profile in the Quebec Family Study. Mol Genet Metab 2009; 97:149-54. [PMID: 19329342 DOI: 10.1016/j.ymgme.2009.02.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 02/27/2009] [Accepted: 02/27/2009] [Indexed: 11/22/2022]
Abstract
BACKGROUND The small, dense LDL phenotype is associated with an increased cardiovascular disease risk. A genome-wide scan performed on 236 nuclear families of the Quebec Family Study (QFS) revealed a QTL for LDL-peak particle size (LDL-PPD) on the 17q21 region. Three positional candidates were identified in this region according to their implication in the phosphoinositide (PI) cycle: the myotubularin-related protein 4 (MTMR4), the phospholipase C, delta 3 (PLCD3), and the diacylglycerol kinase E (DGKE) genes. OBJECTIVES To test the association between MTMR4, PLCD3, and DGKE gene polymorphisms, LDL-PPD and plasma lipid parameters. METHODS Analyses were performed on 680 subjects of QFS. LDL-PPD was measured by gradient gel electrophoresis on non-denaturating 2-16% polyacrylamide gradient gels. Direct sequencing was performed to identify genetic variations within these genes. RESULTS The c.-754G>C, c.183G>A, and c.579C>A DGKE SNPs were significantly associated with higher plasma triglyceride levels (p=0.029, p=0.008, p=0.001, respectively). The c.508C>G and c.890T>G MTMR4 polymorphisms were associated with plasma total-cholesterol concentrations (p=0.02, p=0.02, respectively), while no association was observed with PLCD3 gene polymorphisms. CONCLUSION The c.579C>A DGKE gene polymorphism is associated with plasma triglyceride levels, while MTMR4 SNPs seem to predict variations in plasma cholesterol levels.
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Affiliation(s)
- Guillaume Dolley
- CRML, CHUQ Research Center, 2705 Laurier Boulevard, Que., Canada
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10
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Small-molecule inhibitors of phosphatidylcholine transfer protein/StarD2 identified by high-throughput screening. Anal Biochem 2008; 383:85-92. [PMID: 18762160 DOI: 10.1016/j.ab.2008.07.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 07/28/2008] [Accepted: 07/29/2008] [Indexed: 11/21/2022]
Abstract
Phosphatidylcholine transfer protein (PC-TP, also referred to as StarD2) is a highly specific intracellular lipid-binding protein that catalyzes the transfer of phosphatidylcholines between membranes in vitro. Recent studies have suggested that PC-TP in vivo functions to regulate fatty acid and glucose metabolism, possibly via interactions with selected other proteins. To begin to address the relationship between activity in vitro and biological function, we undertook a high-throughput screen to identify small-molecule inhibitors of the phosphatidylcholine transfer activity of PC-TP. After adapting a fluorescence quench assay to measure phosphatidylcholine transfer activity, we screened 114,752 compounds of a small-molecule library. The high-throughput screen identified 14 potential PC-TP inhibitors. Of these, 6 compounds exhibited characteristics consistent with specific inhibition of PC-TP activity, with IC(50) values that ranged from 4.1 to 95.0muM under conditions of the in vitro assay. These compounds should serve as valuable reagents to elucidate the biological function of PC-TP. Because mice with homozygous disruption of the PC-TP gene (Pctp) are sensitized to insulin action and relatively resistant to the development of atherosclerosis, these inhibitors may also prove to be of value in the management of diabetes and atherosclerotic cardiovascular diseases.
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Scapa EF, Pocai A, Wu MK, Gutierrez-Juarez R, Glenz L, Kanno K, Li H, Biddinger S, Jelicks LA, Rossetti L, Cohen DE. Regulation of energy substrate utilization and hepatic insulin sensitivity by phosphatidylcholine transfer protein/StarD2. FASEB J 2008; 22:2579-90. [PMID: 18347010 DOI: 10.1096/fj.07-105395] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Phosphatidylcholine transfer protein (PC-TP, also known as StarD2) is a highly specific intracellular lipid binding protein with accentuated expression in oxidative tissues. Here we show that decreased plasma concentrations of glucose and free fatty acids in fasting PC-TP-deficient (Pctp(-/-)) mice are attributable to increased hepatic insulin sensitivity. In hyperinsulinemic-euglycemic clamp studies, Pctp(-/-) mice exhibited profound reductions in hepatic glucose production, gluconeogenesis, glycogenolysis, and glucose cycling. These changes were explained in part by the lack of PC-TP expression in liver per se and in part by marked alterations in body fat composition. Reduced respiratory quotients in Pctp(-/-) mice were indicative of preferential fatty acid utilization for energy production in oxidative tissues. In the setting of decreased hepatic fatty acid synthesis, increased clearance rates of dietary triglycerides and increased hepatic triglyceride production rates reflected higher turnover in Pctp(-/-) mice. Collectively, these data support a key biological role for PC-TP in the regulation of energy substrate utilization.
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Affiliation(s)
- Erez F Scapa
- Department of Medicine, Division of Gastroenterology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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Dolley G, Lamarche B, Després JP, Bouchard C, Pérusse L, Vohl MC. Myeloperoxidase gene sequence variations are associated with low-density-lipoprotein characteristics. J Hum Genet 2008; 53:439-446. [DOI: 10.1007/s10038-008-0267-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 02/01/2008] [Indexed: 11/27/2022]
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