title: Angiotensin II type 1 receptor, but no type 2 receptor, interferes with the insulin-induced nitric oxide production in HUVECs.
abstract: OBJECTIVE
  Two subtypes of angiotensin II (ATII) receptor have been defined on the basis of their differential pharmacological and biochemical properties: ATII-type1 receptors (AT(1)-R) and ATII-type2 receptors (AT(2)-R). It has been hypothesized that part of the protective effects on the cardiovascular system of AT(1)-R blockers is mediated by an ATII-mediated overstimulation of AT(2)-R. We hypothesized that the inhibition of AT(1)-R has a stronger impact on insulin-induced nitric oxide (NO) production than ATII-mediated overstimulation of AT(2)-R. Therefore we studied the effect of the inhibition of AT(1)-R and AT(2)-R on ATII-mediated actions in Human Umbilical Vein Endothelial Cells (HUVECs).
  
  
  METHODS
  We analyzed the phosphorylation state of IRS1 at Ser(616) and Ser(312) and on tyrosines after preincubation with PD123319, an inhibitor of AT(2)-R, alone and in combination with losartan, an inhibitor of AT(1)-R. In addition we measured eNOS and Akt activation through the evaluation of their phosphorylation at Ser(1177) and Ser(473) sites respectively.
  
  
  RESULTS
  ATII induces IRS-1 phosphorylation at Ser(312) and Ser(616) through the activation of JNK and ERK 1/2, resulting in the inhibition of the insulin-induced phosphorylation of IRS1 tyrosines, Akt and eNOS. Treatment of HUVECs with AT(1)-R inhibitor restored the insulin signaling leading to NO production, whereas AT(2)-R inhibitor did not have effects on NO production in presence of ATII.
  
  
  CONCLUSIONS
  Our results demonstrate that in presence of AT(1)-R antagonist, the AT(2)-R blockage does not modify the effect obtained with the AT(1)-R inhibition alone. Therefore, a possible positive role of an AT(2)-R overstimulation in condition of AT(1)-R antagonism seems to be irrelevant.
authors.affiliation: Department of Internal and Experimental Medicine, University Magna Græcia of Catanzaro, Catanzaro, Italy.
authors.forename: Ivan
authors.initials: I
authors.lastname: Presta
authors.forename: E Joseph
authors.initials: EJ
authors.lastname: Tassone
authors.forename: Francesco
authors.initials: F
authors.lastname: Andreozzi
authors.forename: Maria
authors.initials: M
authors.lastname: Perticone
authors.forename: Angela
authors.initials: A
authors.lastname: Sciacqua
authors.forename: Irma
authors.initials: I
authors.lastname: Laino
authors.forename: Donatella
authors.initials: D
authors.lastname: Musca
authors.forename: Francesco
authors.initials: F
authors.lastname: Martino
authors.forename: Giorgio
authors.initials: G
authors.lastname: Sesti
authors.forename: Francesco
authors.initials: F
authors.lastname: Perticone
mesh_terms: D000804:Angiotensin II / Q000378:metabolism; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D057912:Angiotensin II Type 2 Receptor Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D004789:Enzyme Activation; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D019808:Losartan / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D044139:Receptor, Angiotensin, Type 2 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012694:Serine; D015398:Signal Transduction; D014443:Tyrosine
chemical_list: C544065:AGTR1 protein, human; D047228:Angiotensin II Type 1 Receptor Blockers; D057912:Angiotensin II Type 2 Receptor Blockers; C526292:IRS1 protein, human; D007093:Imidazoles; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D011725:Pyridines; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D000804:Angiotensin II; C073402:PD 123319; D009569:Nitric Oxide; D014443:Tyrosine; D012694:Serine; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019808:Losartan