Variety of Angiotensin Receptors in 3T3-L1 Preadipose Cells and Differentiated Adipocytes

Abstract

A local paracrine acting angiotensin (ANG) system of preadipocytes and mature adipocytes is involved in metabolic effects and tissue differentiation. The present study reports on the investigation of binding affinities for various angiotensin receptors including their relevance in 3T3-L1 adipocytes and preadipocytes and 3T3-442A preadipocytes. Competitive binding studies using both ¹²⁵I-ANG II and its more stable analogue ¹²⁵I-SARILE for investigating AT₁/AT₂ binding sites in 3T3-L1 preadipocytes reveal a biphasic competition curve with K_Ds at a low and high nanomolar range. By using the AT₂ receptor selective ligand ¹²⁵I-CGP4112A the presence of high affinity AT₂ binding sites in preadipocytes was observed. High nonspecific binding and a low receptor number is characteristic for all these experiments. An AT₄ binding site (binding site for ANG IV) exists in 3T3-L1 and F442A preadipocytes and adipocytes with a high nanomolar K_D. This low binding affinity was confirmed by a biological assay, the IRAP assay (=insulin regulated aminopeptidase assay). IRAP is associated with the AT₄ receptor, which is a binding site at the luminal part of membrane bound IRAP. The curves for competition binding and for inhibition of IRAP activity are superimposable with respect to angiotensin IV. In conclusion, AT₁ and AT₂ binding sites are present in preadipocytes. AT₂ receptor binding affinities are shown in preadipocytes for the first time. The description of a non-AT₁/AT₂ binding site with low affinity remains speculative albeit of high interest because antidiabetic and obesity related effects of angiotensin peptides and sartanes as antagonists are observed at these high concentrations. Local concentrations of ANG II and their degradation products may be extremely high. The low amounts of AT₁ and AT₂ binding sites emphasize the relevance of other binding sites in adipose tissue development and metabolic effects. The AT₄ binding site seems to be one of the predominant receptors in adipose cells. Other degraded, but still bioactive peptides like ANG III, IV and ANG(1–7), activating receptors not influenced by ANG II, could be of importance.

Key words

adipocytes - angiotensin receptors - angiotensin IV - IRAP

References

• 1 Fischer-Posovsky P, Wabitsch M, Hochberg Z. Endocrinology of adipose tissue – An update.  Horm Metab Res. 2007;  39 314-321
• 2 Frayn KN, Tan GD, Karpe F. Adipose tissue: a key target for diabetes pathophysiology and treatment.  Horm Metab Res. 2007;  39 739-742
• 3 Pfeiffer AFH. Adipose tissue and diabetes therapy: Do we hit the target?.  Horm Metab Res. 2007;  39 734-738
• 4 Karlsson C, Lindell K, Ottosson M, Sjostrom L, Carlsson B, Carlsson LMS. Human adipose tissue expresses angiotensinogen and enzymes required for its conversion to angiotensin II.  J Clin Endocrinol Metab. 1998;  83 3925-3929
• 5 Janke J, Engel S, Gorzelniak K, Feldpausch M, Heintze U, Böhnke J, Wellner M, Herse F, Lassalle P, Luft FC, Sharma AM. Adipose tissue and circulating endothelial cell specific molecule-1 in human obesity.  Horm Metab Res. 2006;  38 28-33
• 6 Schling P, Loffler G. Cross talk between adipose tissue cells: impact on pathophysiology.  News Physiol Sci. 2002;  17 99-104
• 7 Schling P, Mallow H, Trindl A, Loffler G. Evidence for a local renin angiotensin system in primary cultured human preadipocytes.  Int J Obes Relat Metab Disord. 1999;  23 336-341
• 8 Frayn KN. Adipose tissue as a buffer for daily lipid flux.  Diabetologia. 2002;  45 1201-1210
• 9 Engeli S, Bohnke J, Gorzelniak K, Janke J, Schling P, Bader M, Luft FC, Sharma AM. Weight loss and the renin-angiotensin-aldosterone system.  Hypertension. 2005;  45 356-362
• 10 Wang C-H, Leung N, Lapointe N, Szeto L, Uffelman KD, Giacca A, Rouleau JL, Lewis GF. Vasopeptidase inhibitor omapatrilat induces profound insulin sensitization and increases myocardial glucose uptake in zucker fatty rats: studies comparing a vasopeptidase inhibitor, angiotensin-converting enzyme inhibitor, and angiotensin II type I receptor blocker.  Circulation. 2003;  107 1923-1929
• 11 Henriksen EJ, Jacob S, Kinnick TR, Teachey MK, Krekler M. Selective angiotensin II receptor receptor antagonism reduces insulin resistance in obese Zucker rats.  Hypertension. 2001;  38 884-890
• 12 Hansson L, Lindholm LH, Niskanen L, Lanke J, Hedner T, Niklason A, Luomanmaki K, Dahlof B, Faire U de, Morlin C, Karlberg BE, Wester PO, Bjorck JE. Effect of angiotensin-converting-enzyme inhibition compared with conventional therapy on cardiovascular morbidity and mortality in hypertension: the Captopril Prevention Project (CAPPP) randomised trial.  Lancet. 1999;  353 611-616
• 13 Chica-Rodriguez S, Cortés-Denia P, Ramirez-Expósito MJ, Martinez-Martos JM. Effects of α₁-adrenergic receptor blockade by doxazosin on renin-angiotensin system-regulated aminopeptidase and vasopressin-degrading activities in male and female rat thalamus.  Horm Metab Res. 2007;  39 813-817
• 14 Yvan-Charvet L, Even P, Bloch-Faure M, Guerre-Millo M, Moustaid-Moussa N, Ferre P, Quignard-Boulange A. Deletion of the angiotensin type 2 receptor (AT2R) reduces adipose cell size and protects from diet-induced obesity and insulin resistance.  Diabetes. 2005;  54 991-999
• 15 Hsieh P-S, Tai Y-H, Loh C-H, Shih K-C, Cheng W-T, Chu C-H. Functional interaction of AT1 and AT2 receptors in fructose-induced insulin resistance and hypertension in rats.  Metabolism. 2005;  54 157-164
• 16 Fujimoto M, Masuzaki H, Tanaka T, Yasue S, Tomita T, Okazawa K, Fujikura J, Chusho H, Ebihara K, Hayashi T, Hosoda K, Nakao K. An angiotensin II AT1 receptor antagonist, telmisartan augments glucose uptake and GLUT4 protein expression in 3T3-L1 adipocytes.  FEBS Lett. 2004;  576 492-497
• 17 Catar RA, Müller G, Heidler J, Schmitz G, Bornstein SR, Morawietz . Low-density lipoproteins induce the renin-angiotensin system and their receptors in human endothelial cells.  Horm Metab Res. 2007;  39 801-805
• 18 Gorzelniak K, Engeli S, Janke J, Luft FC, Sharma AM. Hormonal regulation of the human adipose-tissue renin-angiotensin system: relationship to obesity and hypertension.  J Hypertens. 2002;  20 965-973
• 19 Mallow H, Trindl A, Loffler G. Production of angiotensin II receptors type one (AT1) and type two (AT2) during the differentiation of 3T3-L1 preadipocytes.  Horm Metab Res. 2000;  32 500-503
• 20 Schling P, Loffler G. Effects of angiotensin II on adipose conversion and expression of genes of the renin-angiotensin system in human preadipocytes.  Horm Metab Res. 2001;  33 189-195
• 21 Jones BH, Standridge MK, Moustaid N. Angiotensin II increases lipogenesis in 3T3-L1 and human adipose cells.  Endocrinology. 1997;  138 1512-1519
• 22 Crandall DL, Armellino DC, Busler DE, MacHendry-Rinde B, Kral JG. Angiotensin II receptors in human preadipocytes: role in cell cycle regulation.  Endocrinology. 1999;  140 154-158
• 23 Crandall DL, Herzlinger HE, Saunders BD, Armellino DC, Kral JG. Distribution of angiotensin II receptors in rat and human adipocytes.  J Lipid Res. 1994;  35 1378-1385
• 24 Sharma AM, Janke J, Gorzelniak K, Engeli S, Luft FC. Angiotensin blockade prevents type 2 diabetes by formation of fat cells.  Hypertension. 2002;  40 609-611
• 25 Janke J, Engeli S, Gorzelniak K, Luft FC, Sharma AM. Mature adipocytes inhibit in vitro differentiation of human preadipocytes via angiotensin type 1 receptors.  Diabetes. 2002;  51 1699-1707
• 26 Mendes ACR, Ferreira AJ, Pinheiro SVB, Santos RAS. Chronic infusion of angiotensin-(1-7) reduces heart angiotensin II levels in rats.  Regul Pept. 2005;  125 29-34
• 27 Schupp M, Janke J, Clasen R, Unger T, Kintscher U. Angiotensin type 1 receptor blockers induce peroxisome proliferator-activated receptor-gamma activity.  Circulation. 2004;  109 2054-2057
• 28 Santos RA, Campagnole-Santos MJ, Andrade SP. Angiotensin-(1-7): an update.  Regul Pept. 2000;  91 45-62
• 29 Santos RA, Simoes e Silva AC, Maric C, Silva DM, Machado RP, Buhr I de, Heringer-Walther S, Pinheiro SV, Lopes MT, Bader M, Mendes EP, Lemos VS, Campagnole-Santos MJ, Schultheiss HP, Speth R, Walther T. Angiotensin-(1-7) is an endogenous ligand for the G protein-coupled receptor Mas.  Proc Natl Acad Sci USA. 2003;  100 8258-8263
• 30 Hall KL, Hanesworth JM, Ball AE, Felgenhauer GP, Hosick HL, Harding JW. Identification and characterization of a novel angiotensin binding site in cultured vascular smooth muscle cells that is specific for the hexapeptide (3-8) fragment of angiotensin II, angiotensin IV.  Regul Pept. 1993;  44 225-232
• 31 Albiston AL, MacDowall SG, Matsacos D, Sim P, Clune E, Mustafa T, Lee J, Mendelsohn FAO, Simpson RJ, Connolly LM, Chai SY. Evidence that the angiotensin IV (AT4) receptor is the enzyme insulin-regulated aminopeptidase.  J Biol Chem. 2001;  276 48623-48626
• 32 Schling P. Expression of angiotensin II receptors type 1 and type 2 in human preadipose cells during differentiation.  Horm Metab Res. 2002;  34 709-715
• 33 Lew RA, Mustafa T, Ye S, MacDowall SG, Chai SY, Albiston AL. Angiotensin AT4 ligands are potent, competitive inhibitors of insulin regulated aminopeptidase (IRAP).  J Neurochem. 2003;  86 344-350
• 34 Herbst JJ, Ross SA, Scott HM, Bobin SA, Morris NJ, Lienhard GE, Keller SR. Insulin stimulates cell surface aminopeptidase activity toward vasopressin in adipocytes.  Am J Physiol Endocrinol Metab. 1997;  272 E600-E606
• 35 AbdAlla S, Lother H, Abdel-tawab AM, Quitterer U. The angiotensin II AT2 receptor is an AT1 receptor antagonist.  J Biol Chem. 2001;  276 39721-39726
• 36 Juan C-C, Chien Y, Wu L-Y, Yang W-M, Chang C-L, Lai Y-H, Ho P-H, Kwok CF, Ho L-T. Angiotensin II enhances insulin sensitivity in vitro and in vivo.  Endocrinology. 2005;  2004-1136
• 37 Fliser D, Arnold U, Kohl B, Hartung R, Ritz E. Angiotensin II enhances insulin sensitivity in healthy volunteers under euglycemic conditions.  J Hypertens. 1993;  11 983-988
• 38 Caron AZ, Arguin G, Guillemette G. Angiotensin IV interacts with a juxtamembrane site on AT(4)/IRAP suggesting an allosteric mechanism of enzyme modulation.  Regul Pept. 2003;  113 9-15
• 39 Keller SR, Scott HM, Mastick CC, Aebersold R, Lienhard GE. Cloning and characterization of a novel insulin-regulated membrane aminopeptidase from Glut4 vesicles.  J Biol Chem. 1995;  270 23612-23618
• 40 Keller SR, Davis AC, Clairmont KB. Mice deficient in the insulin-regulated membrane aminopeptidase show substantial decreases in glucose transporter GLUT4 levels but maintain normal glucose homeostasis.  J Biol Chem. 2002;  277 17677-17686
• 41 Green H, Meuth M. An established pre-adipose cell line and its differentiation in culture.  Cell. 1974;  3 127-133
• 42 Inagami T. Molecular biology and signaling of angiotensin receptors: an overview.  J Am Soc Nephrol. 1999;  10 ((Suppl 11)) S2-S7
• 43 Horiuchi M, Lehtonen JYA, Daviet L. Signaling mechanism of the AT2 angiotensin II receptor: crosstalk between AT1 and AT2 receptors in cell growth.  Trends Endocrinol Metabol. 1999;  10 391-396
• 44 Thomas WG, Mendelsohn FA. Angiotensin receptors: form and function and distribution.  Int J Biochem Cell Biol. 2003;  35 774-779
• 45 Gasparo M de, Catt KJ, Inagami T, Wright JW, Unger T. International Union of Pharmacology. XXIII. The Angiotensin II Receptors.  Pharmacol Rev. 2000;  52 415-472
• 46 Zhao Y, Foryst-Ludwig A, Bruemmer D, Culman J, Bader M, Unger T, Kintscher U. Angiotensin II induces peroxisome proliferator-activated receptor gamma in PC12W cells via angiotensin type 2 receptor activation.  J Neurochem. 2005;  94 1395-1401
• 47 Clasen R, Schupp M, Foryst-Ludwig A, Sprang C, Clemenz M, Krikov M, Thone-Reineke C, Unger T, Kintscher U. PPAR{gamma}-activating angiotensin type-1 receptor blockers induce adiponectin.  Hypertension. 2005;  46 137-143
• 48 MacMullen JR, Gibson KJ, Lumbers ER, Burrell JH. 125I[Sar1Ile8] Angiotensin II has a different affinity for AT1 and AT2 receptor subtypes in ovine tissues.  Regul Pept. 2002;  105 83-92
• 49 Greenland K, Wyse B, Sernia C. Identification and characterization of angiotensinIV binding sites in rat neurone and astrocyte cell cultures.  J Neuroendocrinol. 1996;  8 687-693
• 50 Ross SA, Keller SR, Lienhard GE. Increased intracellular sequestration of the insulin-regulated aminopeptidase upon differentiation of 3T3-L1 cells.  Biochem J. 1998;  330 1003-1008

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