title: The angiogenic factor angiopoietin-1 is a proneurogenic peptide on subventricular zone stem/progenitor cells.
abstract: In the adult mammalian brain, the subventricular zone (SVZ) hosts stem cells constantly generating new neurons. Angiopoietin-1 (Ang-1) is an endothelial growth factor with a critical role in division, survival, and adhesion of endothelial cells via Tie-2 receptor activity. Expression of Tie-2 in nonendothelial cells, especially neurons and stem cells, suggests that Ang-1 may be involved in neurogenesis. In the present work, we investigated the putative role of Ang-1 on SVZ neurogenesis. Immature cells from SVZ-derived neurospheres express Ang-1 and Tie-2 mRNA, suggesting a role for the Ang-1/Tie-2 system in the neurogenic niche. Moreover, we also found that Tie-2 protein expression is retained on differentiation in neurons and glial cells. Ang-1 triggered proliferation via activation of the ERK1/2 (extracellular signal-regulated kinase 1/2) mitogen-activated protein kinase (MAPK) kinase pathway but did not induce cell death. Accordingly, coincubation with an anti-Tie-2 neutralizing antibody prevented the pro-proliferative effect of Ang-1. Furthermore, Ang-1 increased the number of NeuN (neuronal nuclear protein)-positive neurons in cultures treated for 7 d, as well as the number of functional neurons, as assessed by monitoring [Ca(2+)](i) rises after application of specific stimuli for neurons and immature cells. The proneurogenic effect of Ang-1 is mediated by Tie-2 activation and subsequent mTOR (mammalian target of rapamycin kinase) mobilization. In agreement, neuronal differentiation significantly decreased after exposure to an anti-Tie-2 neutralizing antibody and to rapamycin. Moreover, Ang-1 elicited the activation of the SAPK (stress-activated protein kinase)/JNK (c-Jun N-terminal kinase) MAPK, involved in axonogenesis. Our work shows a proneurogenic effect of Ang-1, highlighting the relevance of blood vessel/stem cell cross talk in health and disease.
authors.affiliation: Neuroprotection and Neurogenesis in Brain Repair Group, Center for Neuroscience and Cell Biology, Institute of Biochemistry, Faculty of Medicine, Institute of Pharmacology and Experimental Therapeutics, and Institute of Biomedical Research on Light and Image, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Alexandra I
authors.initials: AI
authors.lastname: Rosa
authors.forename: Joana
authors.initials: J
authors.lastname: Gonçalves
authors.forename: Luísa
authors.initials: L
authors.lastname: Cortes
authors.forename: Liliana
authors.initials: L
authors.lastname: Bernardino
authors.forename: João O
authors.initials: JO
authors.lastname: Malva
authors.forename: Fabienne
authors.initials: F
authors.lastname: Agasse
mesh_terms: D042683:Angiopoietin-1 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000502:physiology; D001921:Brain / Q000166:cytology* / Q000254:growth & development; D016923:Cell Death; D002454:Cell Differentiation; D049109:Cell Proliferation; D002552:Cerebral Ventricles / Q000166:cytology / Q000254:growth & development; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D055495:Neurogenesis; D009457:Neuroglia / Q000166:cytology / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009830:Olfactory Bulb / Q000166:cytology / Q000254:growth & development; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D042787:Receptor, TIE-2 / Q000096:biosynthesis / Q000235:genetics; D013234:Stem Cells / Q000166:cytology / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases
chemical_list: D042683:Angiopoietin-1; C467628:Angpt1 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D012333:RNA, Messenger; C546843:mTOR protein, mouse; D042787:Receptor, TIE-2; D017346:Protein Serine-Threonine Kinases; D058570:TOR Serine-Threonine Kinases