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Wulan SN, Bouwman FG, Westerterp KR, Mariman ECM, Plasqui G. Molecular adaptation in adipose tissue in response to overfeeding with a high-fat diet under sedentary conditions in South Asian and Caucasian men. Br J Nutr 2019; 122:241-51. [PMID: 31475655 DOI: 10.1017/S0007114519001260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
For the same BMI, South Asians have a higher body fat percentage than Caucasians. There might be differences in the fatty acid (FA) handling in adipose tissue when both ethnicities are exposed to high-fat overfeeding. The objective of the present study was to investigate the molecular adaptation in relation to FA metabolism in response to overfeeding with a high-fat diet (OHFD) in South Asian and Caucasian men. Ten South Asian men (BMI 18-29 kg/m2) and ten Caucasian men (BMI 22-33 kg/m2), matched for body fat percentage, aged 20-40 years were included. A weight-maintenance diet (30 % fat, 55 % carbohydrate and 15 % protein) was given for 3 d followed by 3 d of overfeeding (150 % energy requirement) with a high-fat diet (60 % fat, 25 % carbohydrate and 15 % protein) while staying in a respiration chamber. Before and after overfeeding, abdominal subcutaneous fat biopsies were taken. Proteins were isolated, analysed and quantified for short-chain 3-hydroxyacyl-CoA dehydrogenase (HADH), carnitine palmitoyl-transferase 1α (CPT1a), adipose TAG lipase, perilipin A (PLINA), perilipin B, lipoprotein lipase and fatty acid binding protein 4 using Western blotting. OHFD decreased the HADH level (P < 0·05) in Caucasians more than in Asians (P < 0·05), but the baseline and after intervention HADH level was relatively higher in Caucasians. The level of CPT1a decreased in South Asians and increased in Caucasians (P < 0·05). PLINA did not change with diet but the level was higher in South Asians (P < 0·05). The observed differences in HADH and PLINA levels as well as in CPT1a response may be important for differences in the long-term regulation of energy (fat) metabolism in these populations.
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Rogne M, Chu DT, Küntziger TM, Mylonakou MN, Collas P, Tasken K. OPA1-anchored PKA phosphorylates perilipin 1 on S522 and S497 in adipocytes differentiated from human adipose stem cells. Mol Biol Cell 2018; 29:1487-1501. [PMID: 29688805 PMCID: PMC6014102 DOI: 10.1091/mbc.e17-09-0538] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Optic atrophy 1 (OPA1) is the A-kinase anchoring protein targeting the pool of protein kinase A (PKA) responsible for perilipin 1 phosphorylation, a gatekeeper for lipolysis. However, the involvement of OPA1-bound PKA in the downstream regulation of lipolysis is unknown. Here we show up-regulation and relocation of OPA1 from mitochondria to lipid droplets during adipocytic differentiation of human adipose stem cells. We employed various biochemical and immunological approaches to demonstrate that OPA1-bound PKA phosphorylates perilipin 1 at S522 and S497 on lipolytic stimulation. We show that the first 30 amino acids of OPA1 are essential for its lipid droplet localization as is OMA1-dependent processing. Finally, our results indicate that presence of OPA1 is necessary for lipolytic phosphorylation of downstream targets. Our results show for the first time, to our knowledge, how OPA1 mediates adrenergic control of lipolysis in human adipocytes by regulating phosphorylation of perilipin 1.
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Affiliation(s)
- Marie Rogne
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
| | - Dinh-Toi Chu
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
| | | | - Maria-Niki Mylonakou
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
| | - Philippe Collas
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0318 Oslo, Norway.,Norewegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, 0424 Oslo, Norway
| | - Kjetil Tasken
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway.,Department of Cancer Immunology, Institute of Cancer Research, Oslo University Hospital, 0424 Oslo, Norway
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Jufvas Å, Rajan MR, Jönsson C, Strålfors P, Turkina MV. Scaffolding protein IQGAP1: an insulin-dependent link between caveolae and the cytoskeleton in primary human adipocytes? Biochem J 2016; 473:3177-88. [PMID: 27458251 DOI: 10.1042/BCJ20160581] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 07/25/2016] [Indexed: 12/15/2022]
Abstract
The ubiquitously expressed IQ motif-containing GTPase activating protein-1 (IQGAP1) is a scaffolding protein implicated in an array of cellular functions, in particular by binding to cytoskeletal elements and signaling proteins. A role of IQGAP1 in adipocytes has not been reported. We therefore investigated the cellular IQGAP1 interactome in primary human adipocytes. Immunoprecipitation and quantitative mass spectrometry identified caveolae and caveolae-associated proteins as the major IQGAP1 interactors alongside cytoskeletal proteins. We confirmed co-localization of IQGAP1 with the defining caveolar marker protein caveolin-1 by confocal microscopy and proximity ligation assay. Most interestingly, insulin enhanced the number of IQGAP1 interactions with caveolin-1 by five-fold. Moreover, we found a significantly reduced abundance of IQGAP1 in adipocytes from patients with type 2 diabetes compared with cells from nondiabetic control subjects. Both the abundance of IQGAP1 protein and mRNA were reduced, indicating a transcriptional defect in diabetes. Our findings suggest a novel role of IQGAP1 in insulin-regulated interaction between caveolae and cytoskeletal elements of the adipocyte, and that this is quelled in the diabetic state.
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Jelani M, Ahmed S, Almramhi MM, Mohamoud HSA, Bakur K, Anshasi W, Wang J, Al-Aama JY. Novel nonsense mutation in the PTRF gene underlies congenital generalized lipodystrophy in a consanguineous Saudi family. Eur J Med Genet 2015; 58:216-21. [DOI: 10.1016/j.ejmg.2015.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 02/12/2015] [Indexed: 01/09/2023]
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Ramos SV, MacPherson REK, Turnbull PC, Bott KN, LeBlanc P, Ward WE, Peters SJ. Higher PLIN5 but not PLIN3 content in isolated skeletal muscle mitochondria following acute in vivo contraction in rat hindlimb. Physiol Rep 2014; 2:2/10/e12154. [PMID: 25318747 PMCID: PMC4254090 DOI: 10.14814/phy2.12154] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Contraction-mediated lipolysis increases the association of lipid droplets and mitochondria, indicating an important role in the passage of fatty acids from lipid droplets to mitochondria in skeletal muscle. PLIN3 and PLIN5 are of particular interest to the lipid droplet-mitochondria interaction because PLIN3 is able to move about within cells and PLIN5 associates with skeletal muscle mitochondria. This study primarily investigated: 1) if PLIN3 is detected in skeletal muscle mitochondrial fraction; and 2) if mitochondrial protein content of PLIN3 and/or PLIN5 changes following stimulated contraction. A secondary aim was to determine if PLIN3 and PLIN5 associate and whether this changes following contraction. Male Long Evans rats (n = 21; age, 52 days; weight = 317 ± 6 g) underwent 30 min of hindlimb stimulation (10 msec impulses, 100 Hz/3 sec at 10-20 V; train duration 100 msec). Contraction induced a ~50% reduction in intramuscular lipid content measured by oil red-O staining of red gastrocnemius muscle. Mitochondria were isolated from red gastrocnemius muscle by differential centrifugation and proteins were detected by western blotting. Mitochondrial PLIN5 content was ~1.6-fold higher following 30 min of contraction and PLIN3 content was detected in the mitochondrial fraction, and unchanged following contraction. An association between PLIN3 and PLIN5 was observed and remained unaltered following contraction. PLIN5 may play a role in mitochondria during lipolysis, which is consistent with a role in facilitating/regulating mitochondrial fatty acid oxidation. PLIN3 and PLIN5 may be working together on the lipid droplet and mitochondria during contraction-induced lipolysis.
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Affiliation(s)
- Sofhia V Ramos
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Rebecca E K MacPherson
- Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Patrick C Turnbull
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Kirsten N Bott
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Paul LeBlanc
- Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Department of Health Science, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Wendy E Ward
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Department of Health Science, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
| | - Sandra J Peters
- Department of Kinesiology, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada Center for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St Catharines, L2S 3A1, Ontario, Canada
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Bouwman FG, Wang P, van Baak M, Saris WHM, Mariman ECM. Increased β-oxidation with improved glucose uptake capacity in adipose tissue from obese after weight loss and maintenance. Obesity (Silver Spring) 2014; 22:819-27. [PMID: 23512564 DOI: 10.1002/oby.20359] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 12/19/2012] [Indexed: 12/12/2022]
Abstract
OBJECTIVE We investigated protein markers for pathways of the fatty acids (FAs) and glucose metabolism in human adipose tissue after a weight loss program by calorie restriction. METHODS Overweight/obese subjects underwent an intervention of 5 weeks of a very low-calorie diet followed by a 3-week weight maintenance diet. Abdominal subcutaneous adipose tissue biopsies were sampled before and after the intervention. Seventeen target proteins as markers of metabolic pathways for the uptake and handling of FAs and glucose were quantified by Western blotting and 11 were retrieved from previous proteomics work. Correlation coefficients were calculated among changes of these proteins. RESULTS Short-chain 3-hydroxyacyl-CoA dehydrogenase, catalase, fatty acid translocase, fatty acid transporter protein 3, adipose triglyceride lipase, fatty acid-binding protein 4, aldolase-C, tubulin-β-5, and annexin A2 changed significantly, and lipoprotein lipase, perilipin 1, and hormone-sensitive lipase tended to change. On an average, increased glucose transporter type 4 translocation was observed, supported by a consistent increase of tyr-24 phosphorylated annexin A2. CONCLUSIONS Our findings suggest that after weight loss by calorie restriction and a short period of maintenance, adipose tissue has an increased capacity for glucose uptake, and lipid mobilization and oxidation. Such metabolic profile may relate to the health benefit of weight loss.
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Affiliation(s)
- Freek G Bouwman
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
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Abstract
The esterification of amphiphilic alcohols with fatty acids is a ubiquitous strategy implemented by eukaryotes and some prokaryotes to conserve energy and membrane progenitors and simultaneously detoxify fatty acids and other lipids. This key reaction is performed by at least four evolutionarily unrelated multigene families. The synthesis of this "neutral lipid" leads to the formation of a lipid droplet, which despite the clear selective advantage it confers is also a harbinger of cellular and organismal malaise. Neutral lipid deposition as a cytoplasmic lipid droplet may be thermodynamically favored but nevertheless is elaborately regulated. Optimal utilization of these resources by lipolysis is similarly multigenic in determination and regulation. We present here a perspective on these processes that originates from studies in model organisms, and we include our thoughts on interventions that target reductions in neutral lipids as therapeutics for human diseases such as obesity and diabetes.
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Affiliation(s)
- Kelly V Ruggles
- Institute of Human Nutrition, Columbia University Medical Center, New York, NY 10032, USA.
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Abstract
Ectoderm and mesoderm can be considered as prototypes for epithelial and mesenchymal cell types. These two embryonic tissues display clear differences in adhesive and motility properties, which are phenomenologically well characterized but remain largely unexplored at the molecular level. Because the key downstream regulations must occur at the plasma membrane and in the underlying actin cortical structures, we have set out to compare the protein content of membrane fractions from Xenopus ectoderm and mesoderm tissues using 2-dimensional difference gel electrophoresis (DiGE). We have thus identified several proteins that are enriched in one or the other tissues, including regulators of the cytoskeleton and of cell signaling. This study represents to our knowledge the first attempt to use proteomics specifically targeted to the membrane-cortex compartment of embryonic tissues. The identified components should help unraveling a variety of tissue-specific functions in the embryo.
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Affiliation(s)
- Renee Wang
- Department of Biology, McGill University, Montreal, Canada
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Storey SM, McIntosh AL, Senthivinayagam S, Moon KC, Atshaves BP. The phospholipid monolayer associated with perilipin-enriched lipid droplets is a highly organized rigid membrane structure. Am J Physiol Endocrinol Metab 2011; 301:E991-E1003. [PMID: 21846905 PMCID: PMC3213997 DOI: 10.1152/ajpendo.00109.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The significance of lipid droplets (LD) in lipid metabolism, cell signaling, and membrane trafficking is increasingly recognized, yet the role of the LD phospholipid monolayer in LD protein targeting and function remains unknown. To begin to address this issue, two populations of LD were isolated by ConA sepharose affinity chromatography: 1) functionally active LD enriched in perilipin, caveolin-1, and several lipolytic proteins, including ATGL and HSL; and 2) LD enriched in ADRP and TIP47 that contained little to no lipase activity. Coimmunoprecipitation experiments confirmed the close association of caveolin and perilipin and lack of interaction between caveolin and ADRP, in keeping with the separation observed with the ConA procedure. The phospholipid monolayer structure was evaluated to reveal that the perilipin-enriched LD exhibited increased rigidity (less fluidity), as shown by increased cholesterol/phospholipid, Sat/Unsat, and Sat/MUFA ratios. These results were confirmed by DPH-TMA, NBD-cholesterol, and NBD-sphingomyelin fluorescence polarization studies. By structure and organization, the perilipin-enriched LD most closely resembled the adipocyte PM. In contrast, the ADRP/TIP47-enriched LD contained a more fluid monolayer membrane, reflecting decreased polarizations and lipid order based on phospholipid fatty acid analysis. Taken together, results indicate that perilipin and associated lipolytic enzymes target areas in the phospholipid monolayer that are highly organized and rigid, similar in structure to localized areas of the PM where cholesterol and fatty acid uptake and efflux occur.
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Affiliation(s)
- Stephen M Storey
- Department of Physiology and Pharmacology, Texas A & M University, Texas Veterinary Medical Center, College Station, Texas, USA
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Abstract
OBJECTIVE Polymerase I and transcript release factor (PTRF) is a protein highly expressed in adipose tissue and is an integral structural component of caveolae. Here, we report on a novel role of PTRF in lipid mobilization. RESEARCH DESIGN AND METHODS PTRF expression was examined in different adipose depots of mice during fasting, refeeding, and after administration of catecholamines and insulin. Involvement of PTRF during lipolysis was studied upon PTRF knockdown and overexpression and mutation of PTRF phosphorylation sites in 3T3-L1 adipocytes. RESULTS PTRF expression in mouse white adipose tissue (WAT) is regulated by nutritional status, increasing during fasting and decreasing to baseline after refeeding. Expression of PTRF also is hormonally regulated because treatment of mice with insulin leads to a decrease in expression, whereas isoproterenol increases expression in WAT. Manipulation of PTRF levels revealed a role of PTRF in lipolysis. Lentiviral-mediated knockdown of PTRF resulted in a marked attenuation of glycerol release in response to isoproterenol. Conversely, overexpressing PTRF enhanced isoproterenol-stimulated glycerol release. Mass-spectrometric analysis revealed that PTRF is phosphorylated at multiple sites in WAT. Mutation of serine 42, threonine 304, or serine 368 to alanine reduced isoproterenol-stimulated glycerol release in 3T3-L1 adipocytes. CONCLUSIONS Our study is the first direct demonstration for a novel adipose tissue-specific function of PTRF as a mediator of lipolysis and also shows that phosphorylation of PTRF is required for efficient fat mobilization.
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Affiliation(s)
- Nabila Aboulaich
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Patricia C. Chui
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - John M. Asara
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
- Department of Signal Transduction, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Jeffrey S. Flier
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Eleftheria Maratos-Flier
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
- Corresponding author: Eleftheria Maratos-Flier,
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Müller G, Jung C, Wied S, Biemer-Daub G, Frick W. Transfer of the glycosylphosphatidylinositol-anchored 5'-nucleotidase CD73 from adiposomes into rat adipocytes stimulates lipid synthesis. Br J Pharmacol 2010; 160:878-91. [PMID: 20590586 PMCID: PMC2935995 DOI: 10.1111/j.1476-5381.2010.00724.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 11/13/2009] [Accepted: 12/13/2009] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND AND PURPOSE In addition to predominant localization at detergent-insoluble, glycolipid-enriched plasma membrane microdomains (DIGs), glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-proteins) have been found associated with lipid droplets (LDs) and adiposomes. Adiposomes are vesicles that are released from adipocytes in response to anti-lipolytic and lipogenic signals, such as H(2)O(2), palmitate and the antidiabetic sulfonylurea drug, glimepiride, and harbour (c)AMP-degrading GPI-proteins, among them the 5-nucleotidase CD73. Here the role of adiposomes in GPI-protein-mediated information transfer was studied. EXPERIMENTAL APPROACH Adiposomes were incubated with isolated rat adipocytes under various conditions. Trafficking of CD73 and lipid synthesis were analysed. KEY RESULTS Upon blockade of GPI-protein trafficking, CD73 specifically associated with DIGs of small, and to a lower degree, large, adipocytes. On reversal of the blockade, CD73 appeared at cytosolic LD in time- adiposome concentration- and signal (H(2)O(2) > glimepiride > palmitate)-dependent fashion. The salt- and carbonate-resistant association of CD73 with structurally intact DIGs and LD was dependent on its intact GPI anchor. Upon incubation with small and to a lower degree, large adipocytes, adiposomes increased lipid synthesis in the absence or presence of H(2)O(2), glimepiride and palmitate and improved the sensitivity toward these signals. Upregulation of lipid synthesis by adiposomes was dependent on the translocation of CD73 with intact GPI anchors from DIGs to LD. CONCLUSIONS The signal-induced transfer of GPI-anchored CD73 from adiposomes via DIGs to LD of adipocytes mediates paracrine upregulation of lipid synthesis within the adipose tissue.
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Affiliation(s)
- G Müller
- Sanofi-Aventis Germany GmbH, Research & Development, Therapeutic Department Metabolism, Frankfurt am Main, Germany.
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Abstract
Pleckstrin is a modular platelet protein consisting of N- and C-terminal pleckstrin homology (PH) domains, a central dishevelled egl10 and pleckstrin (DEP) domain and a phosphorylation region. Following agonist-induced platelet stimulation, dimeric pleckstrin translocates to the plasma membrane, is phosphorylated and then monomerizes. A recent study found that pleckstrin null platelets from a knockout mouse have a defect in granule secretion, actin polymerization and aggregation. However, the mechanism of pleckstrin signaling for this function is unknown. Our recent studies have led to the identification of a novel pleckstrin-binding protein, serum deprivation response protein (SDPR), by co-immunoprecipitation, GST-pulldowns and nanospray quadruple time of flight mass spectrometry. We show that this interaction occurs directly through N-terminal sequences of pleckstrin. Both pleckstrin and SDPR are phosphorylated by protein kinase C (PKC), but the interaction between pleckstrin and SDPR was shown to be independent of PKC inhibition or activation. These results suggest that SDPR may facilitate the translocation of nonphosphorylated pleckstrin to the plasma membrane in conjunction with phosphoinositides that bind to the C-terminal PH domain. After binding of pleckstrin to the plasma membrane, its phosphorylation by PKC exerts downstream effects on platelet aggregation/secretion.
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Affiliation(s)
- Akeel Baig
- Department of Pathology, McMaster University, Hamilton, ON, Canada.
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Hansen CG, Nichols BJ. Exploring the caves: cavins, caveolins and caveolae. Trends Cell Biol 2010; 20:177-86. [PMID: 20153650 DOI: 10.1016/j.tcb.2010.01.005] [Citation(s) in RCA: 222] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 01/07/2010] [Accepted: 01/11/2010] [Indexed: 01/29/2023]
Abstract
Caveolae are ampullate (flask-shaped) invaginations that are abundant in the plasma membrane of many mammalian cell types. Although caveolae are implicated in a wide range of processes including endothelial transcytosis, lipid homeostasis and cellular signalling, a detailed molecular picture of many aspects of their function has been elusive. Until recently, the only extensively characterised protein components of caveolae were the caveolins. Recently, data from several laboratories have demonstrated that a family of four related proteins, termed cavins 1-4, plays key roles in caveolar biogenesis and function. Salient properties of the cavin family include their propensity to form complexes with each other and their different but overlapping tissue distribution. This review summarises recent data on the cavins, and sets them in the context of open questions on the construction and function of caveolae. The discovery of cavins implies that caveolae might have unexpectedly diverse structural properties, in accord with the wide range of functions attributed to these 'little caves'.
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Meex RCR, Schrauwen P, Hesselink MKC. Modulation of myocellular fat stores: lipid droplet dynamics in health and disease. Am J Physiol Regul Integr Comp Physiol 2009; 297:R913-24. [DOI: 10.1152/ajpregu.91053.2008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Storage of fatty acids as triacylglycerol (TAG) occurs in almost all mammalian tissues. Whereas adipose tissue is by far the largest storage site of fatty acids as TAG, subcellular TAG-containing structures—referred to as lipid droplets (LD)—are also present in other tissues. Until recently, LD were considered inert storage sites of energy dense fats. Nowadays, however, LD are increasingly considered dynamic functional organelles involved in many intracellular processes like lipid metabolism, vesicle trafficking, and cell signaling. Next to TAG, LD also contain other neutral lipids such as diacylglycerol. Furthermore, LD are coated by a monolayer of phospholipids decorated with a variety of proteins regulating the delicate balance between LD synthesis, growth, and degradation. Disturbances in LD-coating proteins may result in disequilibrium of TAG synthesis and degradation, giving rise to insulin-desensitizing lipid intermediates, especially in insulin-responsive tissues like skeletal muscle. For a proper and detailed understanding, more information on processes and players involved in LD synthesis and degradation is necessary. This, however, is hampered by the fact that research on LD dynamics in (human) muscle is still in its infancy. A rapidly expanding body of knowledge on LD dynamics originates from studies in other tissues and other species. Here, we aim to review the involvement of LD-coating proteins in LD formation and degradation (LD dynamics) and to extrapolate this knowledge to human skeletal muscle and to explore the role of LD dynamics in myocellular insulin sensitivity.
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Affiliation(s)
- Ruth C. R. Meex
- NUTRIM School for Nutrition, Toxicology and Metabolism, Departments of 1Human Movement Sciences and
| | - Patrick Schrauwen
- Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Matthijs K. C. Hesselink
- NUTRIM School for Nutrition, Toxicology and Metabolism, Departments of 1Human Movement Sciences and
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Bickel PE, Tansey JT, Welte MA. PAT proteins, an ancient family of lipid droplet proteins that regulate cellular lipid stores. Biochim Biophys Acta Mol Cell Biol Lipids. 2009;1791:419-440. [PMID: 19375517 DOI: 10.1016/j.bbalip.2009.04.002] [Citation(s) in RCA: 494] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 02/24/2009] [Accepted: 04/08/2009] [Indexed: 02/07/2023]
Abstract
The PAT family of lipid droplet proteins includes 5 members in mammals: perilipin, adipose differentiation-related protein (ADRP), tail-interacting protein of 47 kDa (TIP47), S3-12, and OXPAT. Members of this family are also present in evolutionarily distant organisms, including insects, slime molds and fungi. All PAT proteins share sequence similarity and the ability to bind intracellular lipid droplets, either constitutively or in response to metabolic stimuli, such as increased lipid flux into or out of lipid droplets. Positioned at the lipid droplet surface, PAT proteins manage access of other proteins (lipases) to the lipid esters within the lipid droplet core and can interact with cellular machinery important for lipid droplet biogenesis. Genetic variations in the gene for the best-characterized of the mammalian PAT proteins, perilipin, have been associated with metabolic phenotypes, including type 2 diabetes mellitus and obesity. In this review, we discuss how the PAT proteins regulate cellular lipid metabolism both in mammals and in model organisms.
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Le Lay S, Blouin CM, Hajduch E, Dugail I. Filling up adipocytes with lipids. Lessons from caveolin-1 deficiency. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1791:514-8. [PMID: 19038362 DOI: 10.1016/j.bbalip.2008.10.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 10/13/2008] [Accepted: 10/28/2008] [Indexed: 02/06/2023]
Abstract
Caveolins are primarily known as the main constituents of the protein coat of caveolae invaginations at the plasma membrane. They have also been found at the surface of intracellular lipid droplets but their function in this lipid storage organelle remains poorly understood. This paper reviews recent studies in adipocytes, the specialized cell type for fatty acid storage, which suggest a role for caveolins in the formation, maintenance or mobilization of lipid droplet stores. These new functions emerged from studies of fat cells in which caveolin expression was invalidated, highlighting the metabolic phenotype of caveolin-deficient mice or human patients who develop progressive lipoatrophy.
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Affiliation(s)
- Soazig Le Lay
- Centre de Recherche des Cordeliers, INSERM, U872, Paris, F-75006, France
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Ohsaki Y, Cheng J, Suzuki M, Shinohara Y, Fujita A, Fujimoto T. Biogenesis of cytoplasmic lipid droplets: from the lipid ester globule in the membrane to the visible structure. Biochim Biophys Acta Mol Cell Biol Lipids. 2009;1791:399-407. [PMID: 18996222 DOI: 10.1016/j.bbalip.2008.10.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 08/09/2008] [Accepted: 10/06/2008] [Indexed: 01/22/2023]
Abstract
The cytoplasmic lipid droplet (CLD) and very low-density lipoprotein are generated from the lipid ester synthesized in the endoplasmic reticulum. The lipid ester deposited between the two membrane leaflets is supposed to bulge toward the cytoplasm to make a nascent CLD, but its size must be below the resolution limit of conventional techniques and the detectable CLD should only form after acquisition of additional lipid esters. The CLD is different from vesicular organelles in that the internal content is highly hydrophobic and the shape is invariably spherical. Due to its unique characteristics, quantitative discordance between the surface and the volume may occur in the growth and/or involution processes of the CLD. The possibility that these processes may give rise to the structural and functional diversities of the CLD is discussed.
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Smith CE, Tucker KL, Yiannakouris N, Garcia-Bailo B, Mattei J, Lai CQ, Parnell LD, Ordovás JM. Perilipin polymorphism interacts with dietary carbohydrates to modulate anthropometric traits in hispanics of Caribbean origin. J Nutr 2008; 138:1852-8. [PMID: 18806092 PMCID: PMC2596596 DOI: 10.1093/jn/138.10.1852] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Perilipin (PLIN) is the major protein surrounding lipid droplets in adipocytes and regulates adipocyte metabolism by modulating the interaction between lipases and triacylglycerol stores. Associations between PLIN gene polymorphisms and obesity risk have been described, but interactions with dietary macronutrients require further attention. We examined whether dietary macronutrients (e.g. carbohydrates and fats) modulated the associations of the common PLIN 11482G > A (rs894160) single nucleotide polymorphism with obesity. We studied a population-based sample of Caribbean-origin Hispanics (n = 920, aged 45-74 y) living in the Boston area. Obesity measures (waist and hip circumference, BMI) did not differ between GG subjects and carriers of the A allele (GA and AA). In multivariate linear regression models, we found a significant interaction between complex carbohydrate intake as a continuous variable and PLIN 11482 G > A genotype for waist circumference (P = 0.002). By dichotomizing complex carbohydrate intake, we found significantly different effects across PLIN 11482G > A genotypes. When complex carbohydrate intake was <144 g/d, waist circumference was larger in PLIN 11482G > A carriers (P = 0.024). Conversely, when complex carbohydrate intake was >/=144 g/d, waist and hip circumferences were less in PLIN 11482G > A carriers (P < 0.05). These interactions were not found for simple sugars or total carbohydrates. We identified a significant gene-diet interaction associated with obesity at the PLIN locus. In subjects with higher complex carbohydrate intake, the minor allele was protective against obesity, whereas in subjects with lower carbohydrate intake, the minor allele was associated with increased obesity. These interactions may be relevant to dietary management of obesity.
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Affiliation(s)
- Caren E. Smith
- Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University School of Medicine, Boston, MA 02111
| | - Katherine L. Tucker
- Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University School of Medicine, Boston, MA 02111
| | | | - Bibiana Garcia-Bailo
- Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University School of Medicine, Boston, MA 02111
| | - Josiemer Mattei
- Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University School of Medicine, Boston, MA 02111
| | - Chao-Qiang Lai
- Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University School of Medicine, Boston, MA 02111
| | - Laurence D. Parnell
- Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University School of Medicine, Boston, MA 02111
| | - José M. Ordovás
- Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University School of Medicine, Boston, MA 02111
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Murphy S, Martin S, Parton RG. Lipid droplet-organelle interactions; sharing the fats. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1791:441-7. [PMID: 18708159 DOI: 10.1016/j.bbalip.2008.07.004] [Citation(s) in RCA: 186] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 06/09/2008] [Accepted: 07/18/2008] [Indexed: 12/20/2022]
Abstract
Lipid droplets (LDs) are key cellular organelles involved in lipid storage and mobilisation. While the major signalling cascades and many of the regulators of lipolysis have been identified, the cellular interactions involved in lipid mobilisation and release remain largely undefined. In non-adipocytes, LDs are small, mobile and interact with other cellular compartments. In contrast, adipocytes primarily contain very large, immotile LDs. The striking morphological differences between LDs in adipocytes and non-adipocytes suggest that key differences must exist in the manner in which LDs in different cell types interact with other organelles. Recent studies have highlighted the complexity of LD interactions, which can be both homotypic, with each other, and heterotypic, with other organelles. The molecules involved in these interactions are also now emerging, including Rab proteins, key regulators of membrane traffic, and caveolin, an integral membrane protein providing a functional link between the cell surface and LDs. Here we summarise recent insights into the cell biology of the LD particularly focussing on the homotypic and heterotypic interactions in both adipocytes and non-adipocytes. We speculate that these interactions may involve inter-organelle membrane contact sites or a hemi-fusion type mechanism to facilitate lipid transfer.
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Affiliation(s)
- Samantha Murphy
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
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Müller G, Wied S, Walz N, Jung C. Translocation of glycosylphosphatidylinositol-anchored proteins from plasma membrane microdomains to lipid droplets in rat adipocytes is induced by palmitate, H2O2, and the sulfonylurea drug glimepiride. Mol Pharmacol 2008; 73:1513-29. [PMID: 18272749 DOI: 10.1124/mol.107.043935] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inhibition of lipolysis by palmitate, H(2)O(2), and the antidiabetic sulfonylurea drug, glimepiride, in rat adipocytes has been shown previously to rely on the concerted degradation of cAMP by the glycosylphosphatidylinositol (GPI)-anchored phosphodiesterase Gce1 and 5'-nucleotidase CD73, which both gain access to the lipid droplets (LDs). The present report demonstrates the translocation of Gce1 and CD73, harboring the intact GPI anchor, from detergent-insoluble glycolipid-enriched plasma membrane domains (DIGs) to the LDs in response to palmitate, H(2)O(2), and glimepiride by analysis of their steady-state distribution using photoaffinity labeling and activity determination as well as of their redistribution after pulse or equilibrium metabolic labeling. We were surprised to find that palmitate, H(2)O(2), and glimepiride induced the activation of the GPI-specific phospholipase C (GPI-PLC) at DIGs of rat adipocytes, leading to anchorless Gce1 and CD73. Inhibition of the GPI-PLC or the presence of nonhydrolyzable substrate analogs of Gce1 and CD73 interfered with the palmitate-, H(2)O(2)-, and glimepiride-induced 1) lipolytic cleavage of Gce1 and CD73, 2) translocation of their GPI-anchored versions from DIGs to LDs, 3) up-regulation of cAMP degradation, and 4) inhibition of lipolysis. These data suggest a novel insulin-independent antilipolytic mechanism in rat adipocytes, which relies on the palmitate-, H(2)O(2)-, and glimepiride-induced and GPI-PLC-dependent translocation of (c)AMP-degrading GPI-anchored proteins from the adipocyte plasma membrane to LDs. The findings may shed new light on the biogenesis and degradation of LDs in response to physiological and pharmacological stimuli.
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Affiliation(s)
- Günter Müller
- Sanofi-Aventis Pharma Germany GmbH, TD Metabolism, Industrial Park Höchst, Bldg. H821, 65926 Frankfurt am Main, Germany.
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Ortegren U, Aboulaich N, Ost A, Strålfors P. A new role for caveolae as metabolic platforms. Trends Endocrinol Metab 2007; 18:344-9. [PMID: 17936007 DOI: 10.1016/j.tem.2007.08.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 08/14/2007] [Accepted: 08/14/2007] [Indexed: 11/19/2022]
Abstract
The plasma membrane of cells functions as a barrier to the environment. Caveolae are minute invaginations of the membrane that selectively carry out the exchange of information and materials with the environment, by functioning as organizers of signal transduction and through endocytosis. Recent findings of uptake of different metabolites and of lipid metabolism occurring in caveolae, point to a new general function of caveolae. As gateways for the uptake of nutrients across the plasma membrane, and as platforms for the metabolic conversion of nutrients, especially in adipocytes, caveolae are now emerging as active centers for many aspects of intermediary metabolism, with implications for our understanding of obesity, diabetes and other metabolic disorders.
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Affiliation(s)
- Unn Ortegren
- Department of Cell Biology and Diabetes Research Centre, Linköping University, SE58185, Linköping, Sweden
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Kovsan J, Ben-Romano R, Souza SC, Greenberg AS, Rudich A. Regulation of adipocyte lipolysis by degradation of the perilipin protein: nelfinavir enhances lysosome-mediated perilipin proteolysis. J Biol Chem 2007; 282:21704-11. [PMID: 17488708 DOI: 10.1074/jbc.m702223200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A decrease in the lipid droplet-associated protein perilipin may constitute a mechanism for enhanced adipocyte lipolysis under nonstimulated (basal) conditions, and increased basal lipolysis has been linked to whole body metabolic dysregulation. Here we investigated whether the lipolytic actions of the human immunodeficiency virus protease inhibitor, nelfinavir, are mediated by decreased perilipin protein content and studied the mechanisms by which it occurs. Time course analysis revealed that the decrease in perilipin protein content preceded the increase in lipolysis. A causative relationship was suggested by demonstrating that nelfinavir potently increased lipolysis in adipocytes derived from mouse embryonal fibroblasts expressing perilipin but not in mouse embryonal fibroblast adipocytes devoid of perilipin and that adenoviral mediated overexpression of perilipin in 3T3-L1 adipocytes blocked the lipolytic actions of nelfinavir. Nelfinavir did not alter mRNA content of perilipin but rather decreased perilipin proteins t((1/2)) from >70 to 12 h. Protein degradation of perilipin in both control and nelfinavir-treated adipocytes could be prevented by inhibiting lysosomal proteolysis using leupeptin or NH(4)Cl but not by the proteasome inhibitor MG-132. We propose that proteolysis of perilipin involving the lysosomal protein degradation machinery may constitute a novel mechanism for enhancing adipocyte lipolysis.
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Affiliation(s)
- Julia Kovsan
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, Israel
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Abstract
PURPOSE OF REVIEW More than 1.1 billion people worldwide are overweight or obese. We know that obesity is determined by a combination of environmental and genetic factors. Although hundreds of obesity candidate genes have been identified through different metabolic pathways, the fundamental basis of obesity resides with excessive storage of triacylglycerides in adipose tissue. RECENT FINDINGS The mechanisms that control the storage and release of triacylglycerides in lipid droplets are complex and poorly understood; yet, they are likely to be crucial to the understanding of the regulation of body weight. In this regard, the family of perilipin, adipophilin and TIP47 proteins may play key roles in obesity. It has recently been shown that variants at the perilipin locus were associated with BMI and obesity risk in females from several population studies. Moreover, the reported interactions between perilipin and dietary factors may shed light on the complex relation between dietary intake and body weight changes observed on an individual basis. SUMMARY These findings support an important role for PLIN as a candidate gene for obesity risk in humans as well as a modulator of dietary response to therapies aimed to reduce body weight and decrease metabolic syndrome risk.
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Affiliation(s)
- E Shyong Tai
- Department of Endocrinology, Singapore General Hospital, Singapore.
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Aboulaich N, Ortegren U, Vener AV, Strålfors P. Association and insulin regulated translocation of hormone-sensitive lipase with PTRF. Biochem Biophys Res Commun 2006; 350:657-61. [PMID: 17026959 DOI: 10.1016/j.bbrc.2006.09.094] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Accepted: 09/20/2006] [Indexed: 11/22/2022]
Abstract
Polymerase I and transcript release factor (PTRF) is in human adipocytes mainly localized at the plasma membrane. This localization was under control of insulin, which translocated PTRF to the cytosol and nucleus, indicating a novel role for PTRF in insulin transcriptional control. In the plasma membrane PTRF was specifically bound to a triacylglycerol-metabolizing subclass of caveolae containing hormone-sensitive lipase (HSL). In response to insulin PTRF was translocated to the cytosol in parallel with HSL. PTRF and HSL were quantitatively immunoprecipitated from the cytosol by antibodies against either PTRF or HSL. The findings indicate also a novel extranuclear function for PTRF in the control of lipolysis.
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Affiliation(s)
- Nabila Aboulaich
- Department of Cell Biology and Diabetes Research Centre, Linköping University, SE58185 Linköping, Sweden
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28
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Sambuy Y. A sideways glance. Genes Nutr 2006; 1:141-142. [PMID: 18850209 PMCID: PMC3454838 DOI: 10.1007/bf02829963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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