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Robbins J, Busquets O, Tong M, de la Monte SM. Dysregulation of Insulin-Linked Metabolic Pathways in Alzheimer's Disease: Co-Factor Role of Apolipoprotein E ɛ4. J Alzheimers Dis Rep 2020; 4:479-493. [PMID: 33344887 PMCID: PMC7739986 DOI: 10.3233/adr-200238] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Brain insulin resistance and deficiency are well-recognized abnormalities in Alzheimer's disease (AD) and likely mediators of impaired energy metabolism. Since apolipoprotein E (APOE) is a major risk factor for late-onset AD, it was of interest to examine its potential contribution to altered insulin-linked signaling networks in the brain. OBJECTIVE The main goal was to evaluate the independent and interactive contributions of AD severity and APOE ɛ4 dose on brain expression of insulin-related polypeptides and inflammatory mediators of metabolic dysfunction. METHODS Postmortem fresh frozen frontal lobe tissue from banked cases with known APOE genotypes and different AD Braak stages were used to measure insulin network polypeptide immunoreactivity with a commercial multiplex enzyme-linked immunosorbent assay (ELISA). RESULTS Significant AD Braak stage and APOE genotype-related abnormalities in insulin, C-peptide, gastric inhibitory polypeptide (GIP), glucaton-like peptide-1 (GLP-1), leptin, ghrelin, glucagon, resistin, and plasminogen activator inhibitor-1 (PAI-1) were detected. The main factors inhibiting polypeptide expression and promoting neuro-inflammatory responses included AD Braak stage and APOE ɛ4/ɛ4 rather than ɛ3/ɛ4. CONCLUSION This study demonstrates an expanded role for impaired expression of insulin-related network polypeptides as well as neuroinflammatory mediators of brain insulin resistance in AD pathogenesis and progression. In addition, the findings show that APOE has independent and additive effects on these aberrations in brain polypeptide expression, but the impact is decidedly greater for APOE ɛ4/ɛ4 than ɛ3/ɛ4.
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Affiliation(s)
- James Robbins
- Alpert Medical School of Brown University, Providence, RI, USA
| | - Oriol Busquets
- Department of Pharmacology, Toxicology and Therapeutic Chemistry, Institute of Neuroscience, University of Barcelona, Barcelona, Spain
| | - Ming Tong
- Alpert Medical School of Brown University, Providence, RI, USA,Department of Medicine, Rhode Island Hospital, Providence, RI, USA
| | - Suzanne M. de la Monte
- Alpert Medical School of Brown University, Providence, RI, USA,Department of Medicine, Rhode Island Hospital, Providence, RI, USA,Departments of Pathology and Laboratory Medicine Providence VA Medical Center, Rhode Island Hospital, and the Women and Infants Hospital of Rhode Island, Providence, RI, USA,Correspondence to: Dr. Suzanne M. de la Monte, MD, MPH, Rhode Island Hospital, 55 Claverick Street, Room 419, Providence, RI 02903, USA. Tel.: +1 401 444 7364; Fax: +1 401 444 2939; E-mail:
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de la Monte SM, Tong M, Daiello LA, Ott BR. Early-Stage Alzheimer's Disease Is Associated with Simultaneous Systemic and Central Nervous System Dysregulation of Insulin-Linked Metabolic Pathways. J Alzheimers Dis 2019; 68:657-668. [PMID: 30775986 PMCID: PMC10084886 DOI: 10.3233/jad-180906] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND Brain insulin resistance is a well-recognized abnormality in Alzheimer's disease (AD) and the likely mediator of impaired glucose utilization that emerges early and progresses with disease severity. Moreover, the rates of mild cognitive impairment (MCI) or AD are significantly greater in people with diabetes mellitus or obesity. OBJECTIVE This study was designed to determine whether systemic and central nervous system (CNS) insulin resistant disease states emerge together and thus may be integrally related. METHODS Insulin-related molecules were measured in paired human serum and cerebrospinal fluid (CSF) samples from 19 with MCI or early AD, and 21 controls using a multiplex ELISA platform. RESULTS In MCI/AD, both the CSF and serum samples had significantly elevated mean levels of C-peptide and an incretin, and reduced expression of Visfatin, whereas only CSF showed significant reductions in insulin and leptin and only serum had increased glucagon, PAI-1, and ghrelin. Although the overall CSF and serum responses reflected insulin resistance together with insulin deficiency, the specific alterations measured in CSF and serum were different. CONCLUSION In MCI and early-stage AD, CNS and systemic insulin-related metabolic dysfunctions, including insulin resistance, occur simultaneously, suggesting that they are integrally related and possibly mediated similar pathogenic factors.
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Affiliation(s)
- Suzanne M de la Monte
- Department of Pathology and Laboratory Medicine (Neuropathology), Rhode Island Hospital, the Providence VA Medical Center, and the Alpert Medical School of Brown University, Providence, RI, USA.,Department of Neurology, Rhode Island Hospital and the Alpert Medical School of Brown University, Providence, RI, USA.,Department of Medicine, Rhode Island Hospital and the Alpert Medical School of Brown University, Providence, RI, USA
| | - Ming Tong
- Department of Medicine, Rhode Island Hospital and the Alpert Medical School of Brown University, Providence, RI, USA
| | - Lori A Daiello
- Department of Neurology, Rhode Island Hospital and the Alpert Medical School of Brown University, Providence, RI, USA.,The Alzheimer's Disease and Memory Disorders Center, Rhode Island Hospital and the Alpert Medical School of Brown University, Providence, RI, USA
| | - Brian R Ott
- Department of Neurology, Rhode Island Hospital and the Alpert Medical School of Brown University, Providence, RI, USA.,The Alzheimer's Disease and Memory Disorders Center, Rhode Island Hospital and the Alpert Medical School of Brown University, Providence, RI, USA
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Mielke JG, Wang YT. Insulin, synaptic function, and opportunities for neuroprotection. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 98:133-86. [PMID: 21199772 DOI: 10.1016/b978-0-12-385506-0.00004-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A steadily growing number of studies have begun to establish that the brain and insulin, while traditionally viewed as separate, do indeed have a relationship. The uptake of pancreatic insulin, along with neuronal biosynthesis, provides neural tissue with the hormone. As well, insulin acts upon a neuronal receptor that, although a close reflection of its peripheral counterpart, is characterized by unique structural and functional properties. One distinction is that the neural variant plays only a limited part in neuronal glucose transport. However, a number of other roles for neural insulin are gradually emerging; most significant among these is the modulation of ligand-gated ion channel (LGIC) trafficking. Notably, insulin has been shown to affect the tone of synaptic transmission by regulating cell-surface expression of inhibitory and excitatory receptors. The manner in which insulin regulates receptor movement may provide a cellular mechanism for insulin-mediated neuroprotection in the absence of hypoglycemia and stimulate the exploration of new therapeutic opportunities.
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Affiliation(s)
- John G Mielke
- Faculty of Applied Health Sciences, Department of Health Studies and Gerontology, University of Waterloo, Waterloo, Ontario, Canada
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Mannerström M, Tähti H. Modulation of glucose uptake in glial and neuronal cell lines by selected neurological drugs. Toxicol Lett 2004; 151:87-97. [PMID: 15177644 DOI: 10.1016/j.toxlet.2004.01.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Revised: 01/06/2004] [Accepted: 01/09/2004] [Indexed: 11/25/2022]
Abstract
Glucose is the main energy source of brain cells. The transport of glucose across the cell membrane is the first step of its utilization. Any modification in glucose uptake capacity may cause deleterious effects on neural cell functions. In the present study, 3-O-methyl-D-glucose (3-OMG) uptake and its modulation by selected neurological drugs (amitriptyline, selegiline, carbamazepine and phenytoin) were studied in differentiated (with retinoic acid and 12-O-tetradecanoyl phorbol 13-acetate) and undifferentiated neuroblastoma SH-SY5Y and astrocytoma U-373 MG cell lines, using tracer methods. The expression of glucose transporters was studied by immunocytochemistry. SH-SY5Y and U-373 MG cells showed differences both in their glucose uptake properties and in the modulation of glucose uptake by the drugs, which might reflect different specialization of neuronal and glial cells in vivo. While selegiline and amitriptyline had a minor and variable effect on 3-OMG uptake in all cell cultures, the anticonvulsants carbamazepine and phenytoin increased 3-OMG uptake in U-373 MG cells, but decreased that in SH-SY5Y cells. Differentiated SH-SY5Y cells were more sensitive to the effects of the anticonvulsants than undifferentiated SH-SY5Y cells. The results suggest that, the cell lines are promising neural models for the evaluation of drug side effects due to disturbances in glucose uptake.
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Affiliation(s)
- Marika Mannerström
- Medical School, Cell Research Center, FIN-33014 University of Tampere, Tampere 33101, Finland
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Sims KD, Straff DJ, Robinson MB. Platelet-derived growth factor rapidly increases activity and cell surface expression of the EAAC1 subtype of glutamate transporter through activation of phosphatidylinositol 3-kinase. J Biol Chem 2000; 275:5228-37. [PMID: 10671571 DOI: 10.1074/jbc.275.7.5228] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Na(+)-dependent glutamate transporters are the primary mechanism for removal of excitatory amino acids (EAAs) from the extracellular space of the central nervous system and influence both physiologic and pathologic effects of these compounds. Recent evidence suggests that the activity and cell surface expression of a neuronal subtype of glutamate transporter, EAAC1, are rapidly increased by direct activation of protein kinase C and are decreased by wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3-K). We hypothesized that this regulation could be analogous to insulin-induced stimulation of the GLUT4 subtype of glucose transporter, which is dependent upon activation of PI3-K. Using C6 glioma, a cell line that endogenously and selectively expresses EAAC1, we report that platelet-derived growth factor (PDGF) increased Na(+)-dependent L-[(3)H]-glutamate transport activity within 30 min. This effect of PDGF was not due to a change in total cellular EAAC1 immunoreactivity but was instead correlated with an increase cell surface expression of EAAC1, as measured using a membrane impermeant biotinylation reagent combined with Western blotting. A decrease in nonbiotinylated intracellular EAAC1 was also observed. These studies suggest that PDGF causes a redistribution of EAAC1 from an intracellular compartment to the cell surface. These effects of PDGF were accompanied by a 35-fold increase in PI3-K activity and were blocked by the PI3-K inhibitors, wortmannin and LY 294002, but not by an inhibitor of protein kinase C. Other growth factors, including insulin, nerve growth factor, and epidermal growth factor had no effect on glutamate transport nor did they increase PI3-K activity. These studies suggest that, as is observed for insulin-mediated translocation of GLUT4, EAAC1 cell surface expression can be rapidly increased by PDGF through activation of PI3-K. It is possible that this PDGF-mediated increase in EAAC1 activity may contribute to the previously demonstrated neuroprotective effects of PDGF.
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Affiliation(s)
- K D Sims
- Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Singh SP, Gao Y, Kunapuli SP, Ravindra R. Ethanol inhibits G-protein-mediated glucose uptake by C6 glioma cells. Neuroreport 1999; 10:595-9. [PMID: 10208596 DOI: 10.1097/00001756-199902250-00028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The mechanism of ethanol inhibition of glucose uptake was investigated using C6 glioma cells. Basal [3H]2-deoxy-D-glucose (2DG) uptake by C6 cells was inhibited by ethanol in a concentration-dependent manner. Fifty, 75 and 100 mM ethanol significantly inhibited basal 2DG uptake by 12, 20 and 23%, respectively (p < 0.05). Carbachol (an agonist acting via G protein-coupled receptors) stimulated the uptake by 26% (p < 0.05). In the presence of 100 mM ethanol, the ability of carbachol to stimulate 2DG uptake was abolished. In contrast, ethanol did not inhibit the ability of insulin to stimulate 2DG uptake. These results suggest that ethanol inhibits 2DG uptake by selectively interfering with G protein-mediated signal transduction pathway.
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Affiliation(s)
- S P Singh
- Endocrine-Metabolic Division, Veterans Affairs Medical Center and Finch University of Health Sciences/The Chicago Medical School North Chicago, IL 60064, USA
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Singh SP, Gao Y, Singh LD, Kunapuli SP, Ravindra R. Role of microtubules in glucose uptake by C6 glioma cells. PHARMACOLOGY & TOXICOLOGY 1998; 83:83-9. [PMID: 9783325 DOI: 10.1111/j.1600-0773.1998.tb01448.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Drugs that influence tubulin function were used to investigate the role of microtubules in hexose uptake by C6 glioma cells. In C6 cells, colchicine and vinblastine (which inhibit tubulin polymerization) inhibited radioactive [3H]2-deoxy-D-glucose uptake by about 30%. Paclitaxel (which promotes tubulin polymerization) stimulated hexose uptake by about 25%. To further demonstrate that microtubules play a role in hexose uptake, C6 cells were transfected with GLUT1 cDNA and then challenged with 100 nM paclitaxel. In GLUT1-transfected cells paclitaxel stimulated 2-deoxy-D-glucose uptake by about 35%. To study the role of tubulin in agonist-stimulated hexose uptake, the effect of colchicine on carbachol-induced uptake was next examined. Hexose uptake was increased with carbachol in concentration-dependent manner which was abolished by pretreatment with colchicine. To examine the specificity of the inhibitory effect of colchicine on G protein-mediated signal transduction pathway, the influence of colchicine on insulin (which acts via tyrosine kinase pathway) stimulation of 2-deoxy-D-glucose uptake was investigated. Hexose uptake was increased by insulin in a concentration-dependent manner which was unaffected by pretreatment with colchicine. These results suggest that microtubules are involved in basal and carbachol-stimulated glucose uptake by C6 cells.
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Affiliation(s)
- S P Singh
- Endocrine-Metabolic Division, Veterans Affairs Medical Center, North Chicago, Illinois, USA
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Abstract
The role of G proteins in glucose uptake was investigated using C6 glioma cells. Carbachol (an agonist acting via G protein coupled receptors) and 5'-guanylylimidodiphosphate (Gpp(NH)p; a nonhydrolysable guanine nucleotide analog which bypasses the receptors and directly activates G proteins) stimulated [3H]2-deoxy-D-glucose (2DG) uptake by C6 cells, suggesting that hexose uptake is a G protein-mediated process. To identify the G protein involved in glucose uptake by C6 cells, the effect of carbachol on 2DG uptake was examined in the presence of pertussis toxin. Pertussis toxin treatment did not alter the ability of C6 cells to respond to carbachol, ruling out the involvement of G(i alpha) in 2DG uptake. C6 cells were transfected with G(q alpha) or GLUT1 cDNA for 48 h, exposed to 1 mM carbachol for 2 h, and processed for 2DG uptake. Carbachol stimulated 2DG uptake in both G(q alpha) and GLUT1-transfected cells. Gpp(NH)p, also stimulated 2DG uptake in G(q alpha) and GLUT1-transfected cells. These results suggest that muscarinic receptor coupling to G(q alpha) regulates hexose uptake in C6 cells.
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Affiliation(s)
- S P Singh
- Endocrine-Metabolic Division, Veterans Affairs Medical Center and Finch University of Health Sciences/The Chicago Medical School, North Chicago, IL 60064, USA
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Singh SP, Gao Y, Kunapuli SP, Ravindra R. Role of Gq alpha in insulin-stimulated glucose uptake by C6 glioma cells. Neuroreport 1997; 8:2359-63. [PMID: 9243640 DOI: 10.1097/00001756-199707070-00051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To investigate the possibility that insulin-stimulated glucose uptake in C6 cells is due to transactivation of a G protein-mediated pathway, the role of Gq alpha in insulin signaling was studied. Insulin stimulation of [3H]2-deoxy-D-glucose (2DG) uptake by C6 cells was time- and concentration-dependent: at a concentration of 1 microM, insulin stimulated 2DG uptake by C6 cells by about 30% (p < 0.05). Pertussis toxin treatment of C6 cells did not alter the ability of insulin (1 microM) to promote 2DG uptake, ruling out the involvement of Gion in insulin-stimulated hexose uptake. Next, C6 cells were transfected with Gq alpha cDNA for 48 h, challenged with 1 microM insulin, and 2DG uptake by the cells was determined. Insulin-stimulated 2DG uptake was 1.14 +/- 0.03 and 1.75 +/- 0.19 nmol/min/mg protein in mock- and Gq alpha-transfected cells, respectively (p < 0.05); insulin stimulated 2DG uptake in Gq alpha-transfected cells by 54%. These results suggest an involvement of Gq alpha in the transactivation of the G protein signal transduction pathway by insulin.
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Affiliation(s)
- S P Singh
- Endocrine-Metabolic Division, Veterans Affairs Medical Center, Chicago, IL, USA
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Livnat T, Chen-Zion M, Brodie C, Beitner R. Rapid stimulatory effect of insulin on binding of glycolytic enzymes to cytoskeleton of C-6 glial cells, and the antagonistic action of calmodulin inhibitors. Endocrine 1995; 3:319-22. [PMID: 21153182 DOI: 10.1007/bf03021413] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/1995] [Accepted: 01/10/1995] [Indexed: 11/30/2022]
Abstract
Insulin was shown in our previous experiments to induce an increase in binding of glycolytic enzymes to muscle cytoskeleton. We show here the same stimulatory effect of insulin in C-6 glial cells in culture. In these cells, like in muscle, a short time of incubation with insulin (1-10 min) induced an increase in cytoskeleton bound phosphofructokinase and aldolase. This stimulatory effect of insulin could be prevented by treatment with calmodulin antagonists trifluoperazine, thioridazine or CGS 9343 B (a potent and selective inhibitor of calmodulin activity), which strongly suggests that calmodulin is involved in this action of insulin. Our previous experiments have shown that growth factors and Ca(2+) also induce a rapid, calmodulin-mediated stimulation of binding of glycolytic enzymes to cytoskeleton. The present and previous results suggest that the rapid binding of glycolytic enzymes to cytoskeleton, may be a general mechanism, in different cells, in signal transduction of insulin, growth factors and other Ca(2+) -mobilizing hormones. The accelerated cytoskeletal glycolysis will supply local ATP, which is required for the rapid cytoskeletal-membrane rearrangements following the binding of hormone to its receptor.
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Affiliation(s)
- T Livnat
- Dept. of Life Sciences, Bar-llan University Ramat Can, 52900, Israel
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Abstract
Insulin treatment increases the SN-1,2-diacylglycerol (DAG) concentration in skeletal muscle. Because DAG may participate in transmission or modulation of the insulin receptor signal, we examined the effect of insulin on total DAG and on different DAG species in isolated rat hemidiaphragms incubated with 5 mmol/L glucose. Five DAG species (16:0-18:1 omega 9, 16:0-18:1 omega 7, 18:0-18:1 omega 9, 18:0-18:2 omega 6, and 18:1-18:2) were identified and quantified. After a 5-minute incubation with 60 nmol/L insulin, neither total DAG nor a DAG species increased; exposure to insulin for 10 or 20 minutes increased the concentration of total DAG and of several DAG species. Insulin did not increase DAG in muscles incubated without glucose. Two sources for the insulin-mediated DAG increase were considered: phosphatidylcholine (PC) hydrolysis and de novo DAG synthesis from glucose. Concentrations of choline and phosphocholine in muscle were not increased after 10-minute incubations with insulin. However, insulin increased 14C incorporation from [U-14C]glucose into DAG, triacylglycerol (TAG), and total lipids approximately threefold. Okadaic acid (OKA), an inhibitor of phosphoprotein phosphatases 1 and 2A, increased muscle DAG content and synthesis from glucose, similar to the effect of insulin. Doses of OKA or insulin that increased DAG mass greatly exceeded those required for stimulation of glucose transport. The insulin-mediated, relatively slow increase in muscle DAG observed here likely reflects primarily de novo synthesis from glucose. This effect would be downstream of insulin stimulation of glucose transport. However, a possible insulin-mediated, rapid transient increase in muscle DAG content and PC hydrolysis cannot be ruled out by our studies.
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Affiliation(s)
- K P Boggs
- Department of Medicine, Medical University of South Carolina, Charleston 29425
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Farese RV, Standaert ML, Yamada K, Huang LC, Zhang C, Cooper DR, Wang Z, Yang Y, Suzuki S, Toyota T. Insulin-induced activation of glycerol-3-phosphate acyltransferase by a chiro-inositol-containing insulin mediator is defective in adipocytes of insulin-resistant, type II diabetic, Goto-Kakizaki rats. Proc Natl Acad Sci U S A 1994; 91:11040-4. [PMID: 7972005 PMCID: PMC45162 DOI: 10.1073/pnas.91.23.11040] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Type II diabetic Goto-Kakizaki (GK) rats were insulin-resistant in euglycemic-hyperinsulinemic clamp studies. We therefore examined insulin signaling systems in control Wistar and diabetic GK rats. Glycerol-3-phosphate acyltransferase (G3PAT), which is activated by headgroup mediators released from glycosyl-phosphatidylinositol (GPI), was activated by insulin in intact and cell-free adipocyte preparations of control, but not diabetic, rats. A specific chiro-inositol-containing inositol phosphoglycan (IPG) mediator, prepared from beef liver, bypassed this defect and comparably activated G3PAT in cell-free adipocyte preparations of both diabetic GK and control rats. A myo-inositol-containing IPG mediator did not activate G3PAT. Relative to control adipocytes, labeling of GPI by [3H]glucosamine was diminished by 50% and insulin failed to stimulate GPI hydrolysis in GK adipocytes. In contrast to GPI-dependent G3PAT activation, insulin-stimulated hexose transport was intact in adipocytes and soleus and gastrocnemius muscles of the GK rat, as was insulin-induced activation of mitogen-activated protein kinase and protein kinase C. We conclude that (i) chiro-inositol-containing IPG mediator activates G3PAT during insulin action, (ii) diabetic GK rats have a defect in synthesizing or releasing functional chiro-inositol-containing IPG, and (iii) defective IPG-regulated intracellular glucose metabolism contributes importantly to insulin resistance in diabetic GK rats.
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Affiliation(s)
- R V Farese
- J. A. Haley Veterans' Hospital, Tampa, FL 33612
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Standaert ML, Musunuru K, Yamada K, Cooper DR, Farese RV. Insulin-stimulated phosphatidylcholine hydrolysis, diacylglycerol/protein kinase C signalling, and hexose transport in pertussis toxin-treated BC3H-1 myocytes. Cell Signal 1994; 6:707-16. [PMID: 7857772 DOI: 10.1016/0898-6568(94)90052-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Pertussis toxin was used to block insulin-stimulated phosphatidylinositol (PI)-glycan hydrolysis, consequent de novo synthesis of phosphatidic acid (PA) and the diacylglycerol (DAG) production that results from these two related processes in BC3H-1 myocytes. In contrast, pertussis toxin pretreatment did not inhibit insulin-stimulated hydrolysis of phosphatidylcholine (PC) which was found to be at least partly due to activation of a phospholipase D. Moreover, pertussis toxin-insensitive PC hydrolysis was accompanied by rapid biphasic increases in DAG and translocative activation of protein kinase C (PKC). Insulin-stimulated glucose transport was also insensitive to pertussis toxin pretreatment. Our findings suggest that insulin-stimulated PC hydrolysis pays an important role in DAG/PKC signalling during insulin action.
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