title: Endothelins reciprocally regulate VEGF-A and angiopoietin-1 production in cultured rat astrocytes: implications on astrocytic proliferation.
abstract: Vascular endothelial growth factors (VEGFs) and angiopoietins (ANGs) are involved in pathophysiological responses in damaged nerve tissues. Astrocytes produce VEGFs and ANGs upon brain ischemia and traumatic injury. To clarify the extracellular signals regulating VEGF and ANG production, effects of endothelins (ETs), a family of endothelium-derived peptides, were examined in cultured rat astrocytes. ET-1 (100 nM) and Ala(1,3,11,15)-ET-1 (100 nM), an ET(B) receptor agonist, increased VEGF-A mRNA levels in cultured astrocytes, while ANG-1 mRNA was decreased by ETs. ET-1 did not affect astrocytic VEGF-B, placental growth factor (PLGF), and ANG-2 mRNA levels. The effects of ET-1 on VEGF-A and ANG-1 mRNAs were inhibited by BQ788, an ET(B) antagonist. Release of VEGF-A proteins from cultured astrocytes was increased by ET-1. In contrast, ET-1 reduced release of astrocytic ANG-1. Exogenous ET-1 (100 nM) and VEGF(165) (100 ng/mL), an isopeptide of VEGF-A, stimulated bromodeoxyuridine (BrdU) incorporation into cultured astrocytes. Treatment with ET-1 and VEGF(165) increased the numbers of cyclin D1-positive astrocytes. Exogenous ANG-1 (250 ng/mL) did not stimulate the BrdU incorporation. Increases in BrdU incorporation by ET-1 and VEGF(165) were not affected by ANG-1. In 60-70% confluent cultures, SU4312 (10 μM), a VEGF receptor tyrosine kinase inhibitor, partially reduced the effects of ET-1 on BrdU incorporation and cyclin D1 expression. ET-induced BrdU incorporation and cyclin D1 expression were reduced by a neutralizing antibody against VEGF-A. Our findings suggest that ET-1 is a factor regulating astrocytic VEGF-A and ANG-1, and that increased VEGF-A production potentiates ET-induced astrocytic proliferation by an autocrine mechanism.
authors.affiliation: Faculty of Pharmacy, Laboratory of Pharmacology, Osaka Ohtani University, 3-11-1 Nishikiori-Kita, Tonda-bayashi, Osaka, Japan. koyamay@osaka-ohtani.ac.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Koyama
authors.forename: Yuko
authors.initials: Y
authors.lastname: Maebara
authors.forename: Mio
authors.initials: M
authors.lastname: Hayashi
authors.forename: Ryuji
authors.initials: R
authors.lastname: Nagae
authors.forename: Shogo
authors.initials: S
authors.lastname: Tokuyama
authors.forename: Shotaro
authors.initials: S
authors.lastname: Michinaga
mesh_terms: D042683:Angiopoietin-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D019898:Autocrine Communication / Q000187:drug effects / Q000502:physiology; D001973:Bromodeoxyuridine / Q000037:antagonists & inhibitors / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D019332:Endothelin-1 / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D015854:Up-Regulation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D042683:Angiopoietin-1; C467629:Angpt1 protein, rat; D019332:Endothelin-1; D009842:Oligopeptides; D010880:Piperidines; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; C086539:BQ 788; D001973:Bromodeoxyuridine