title: Glial cell line-derived neurotrophic factor influences proliferation of osteoblastic cells.
abstract: Little is known about the role of neurotrophic growth factors in bone metabolism. This study investigated the short-term effects of glial cell line-derived neurotrophic factor (GDNF) on calvarial-derived MC3T3-E1 osteoblasts. MC3T3-E1 expressed GDNF as well as its canonical receptors, GFRα1 and RET. Addition of recombinant GDNF to cultures in serum-containing medium modestly inhibited cell growth at high concentrations; however, under serum-free culture conditions GDNF dose-dependently increased cell proliferation. GDNF effects on cell growth were inversely correlated with its effect on alkaline phosphatase (AlP) activity showing a significant dose-dependent inhibition of relative AlP activity with increasing concentrations of GDNF in serum-free culture medium. Live/dead and lactate dehydrogenase assays demonstrated that GDNF did not significantly affect cell death or survival under serum-containing and serum-free conditions. The effect of GDNF on cell growth was abolished in the presence of inhibitors to GFRα1 and RET indicating that GDNF stimulated calvarial osteoblasts via its canonical receptors. Finally, this study found that GDNF synergistically increased tumor necrosis factor-α (TNF-α)-stimulated MC3T3-E1 cell growth suggesting that GDNF interacted with TNF-α-induced signaling in osteoblastic cells. In conclusion, this study provides evidence for a direct, receptor-mediated effect of GDNF on osteoblasts highlighting a novel role for GDNF in bone physiology.
authors.affiliation: School of Dentistry, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
authors.forename: Zoe
authors.initials: Z
authors.lastname: Gale
authors.forename: Paul R
authors.initials: PR
authors.lastname: Cooper
authors.forename: Ben A
authors.initials: BA
authors.lastname: Scheven
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D002452:Cell Count; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D051096:Proto-Oncogene Proteins c-ret / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012886:Skull / Q000166:cytology
chemical_list: C494988:Gfra1 protein, mouse; D051100:Glial Cell Line-Derived Neurotrophic Factor; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D051096:Proto-Oncogene Proteins c-ret; D001973:Bromodeoxyuridine