title: Fibroblast growth factor and endothelin-1 receptors mediate the response of human striatal precursor cells to hypoxia.
abstract: Fetal striatal transplantation has emerged as a new therapeutic strategy in Huntington's disease (HD). Hypoxia is one of the microenvironmental stress conditions to which fetal tissue is exposed as soon as it is isolated and transplanted into the diseased host brain. Mechanisms that support neuroblast survival and replenishment of damaged cells within the HD brain in the hypoxic condition have yet to be fully elucidated. This study is aimed at investigating the molecular pathways associated with the hypoxic condition in human fetal striatal neuroblasts (human striatal precursor (HSP) cells), using the hypoxia-mimetic agent cobalt chloride (CoCl2). We analyzed the effect of CoCl2 on HSP cell proliferation and on the expression of hypoxia-related proteins, such as hypoxia-inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF). Moreover, we evaluated fibroblast growth factor 2 (FGF2; 50ng/ml) and endothelin-1 (ET-1; 100nM) proliferative/survival effects in HSP cells in normoxic and hypoxic conditions. Dose-response experiments using increasing concentrations of CoCl2 (50-750μM) showed that the HSP cell growth was unaffected after 24h, while it increased at 48h, with the maximal effect observed at 400μM. In contrast, cell survival was impaired at 72h. Hypoxic conditions determined HIF-1α protein accumulation and increased gene and protein expression of VEGF, while FGF2 and ET-1 significantly stimulated HSP cell proliferation both in normoxic and hypoxic conditions, thus counteracting the apoptotic CoCl2 effect at 72h. The incubation with selective receptor (FGFR1, endothelin receptor A (ETA) and endothelin receptor B (ETB)) inhibitors abolished the FGF2 and ET-1 neuroprotective effect. In particular, ET-1 stimulated HSP cell survival through ETA in normoxic conditions and through ETB during hypoxia. Accordingly, ETA expression was down-regulated, while ETB expression was up-regulated by CoCl2 treatment. Overall, our results support the idea that HSP cells possess the machinery for their adaptation to hypoxic conditions and that neurotrophic factors, such as FGF2 and ET-1, may sustain neurogenesis and long-term survival through complex receptor-mediated mechanisms.
authors.affiliation: Department of Experimental and Clinical Medicine, University of Florence, Largo Brambilla 3, 50134 Florence, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Ambrosini
authors.affiliation: Department of Experimental and Clinical Medicine, University of Florence, Largo Brambilla 3, 50134 Florence, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Sarchielli
authors.affiliation: Department of Experimental and Clinical Biomedical Science "Mario Serio", University of Florence, Viale G.B. Morgagni 50, 50139 Florence, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Comeglio
authors.affiliation: Department of Experimental and Clinical Biomedical Science "Mario Serio", University of Florence, Viale G.B. Morgagni 50, 50139 Florence, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Porfirio
authors.affiliation: Department of Surgery and Translational Medicine, University of Florence, Largo Brambilla 3, 50134 Florence, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Gallina
authors.affiliation: Department of Experimental and Clinical Medicine, University of Florence, Largo Brambilla 3, 50134 Florence, Italy. Electronic address: a.morelli@unifi.it.
authors.forename: A
authors.initials: A
authors.lastname: Morelli
authors.affiliation: Department of Experimental and Clinical Medicine, University of Florence, Largo Brambilla 3, 50134 Florence, Italy.
authors.forename: G B
authors.initials: GB
authors.lastname: Vannelli
mesh_terms: D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002491:Central Nervous System Agents / Q000633:toxicity; D003035:Cobalt / Q000633:toxicity; D003342:Corpus Striatum / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000378:metabolism*; D053686:Fetal Stem Cells / Q000502:physiology*; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D058953:Neural Stem Cells / Q000502:physiology*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D002491:Central Nervous System Agents; D019332:Endothelin-1; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D003035:Cobalt; D005346:Fibroblast Growth Factors; D044925:Oxidoreductases Acting on CH-CH Group Donors; C499055:DHCR24 protein, human; C496348:FGFR1 protein, human; D051496:Receptor, Fibroblast Growth Factor, Type 1; C018021:cobaltous chloride
keywords: CoCl(2); ETA; ETB; FGF2; Huntington’s disease; human striatal neuroblasts