title: FoxO3a negatively regulates nerve growth factor-induced neuronal differentiation through inhibiting the expression of neurochondrin in PC12 cells.
abstract: Forkhead box O3 (FoxO3a) is a forkhead family transcription factor playing important roles in non-neuronal differentiation, metabolism, proliferation, and survival, but its role in neuronal differentiation remains unclear. In the present study, we investigated the role of FoxO3a in neuronal differentiation and its underlying mechanisms. Our results showed that overexpression of FoxO3a inhibited neuronal differentiation of PC12 cells induced by nerve growth factor (NGF) while knockdown of FoxO3a by siRNA enhanced NGF-induced differentiation. DNA microarray analysis and quantitative reverse transcription PCR (RT-PCR) showed that the overexpression of FoxO3a significantly attenuated expression of neurochondrin (NCDN), a neurite outgrowth-related protein, in PC12 cells, while knocking down the expression of FoxO3a had the opposite effect. Bioinformatic studies found that the regulatory region of NCDN promoter contained multiple FoxO3a binding sites. Dual-luciferase reporter assay with report gene containing NCDN promoter showed that FoxO3a significantly decreased the transcription activity of NCDN promoter. These results indicate that NCDN is a direct downstream target of FoxO3a which negatively regulates the expression of NCDN. Interestingly, NGF-induced NCDN expression and cell differentiation was blocked by the inhibition of phosphatidylinositol-3-kinase (PI3K)-protein kinase B (PKB, Akt) signal pathway (activation of FoxO3a) and overexpression of FoxO3a. Moreover, knockdown of NCDN by siRNA blocked NGF-induced neuronal differentiation of PC12 cells while overexpression of NCDN significantly promoted neurite outgrowth. These results put together demonstrate that NCDN plays an important role in NGF-induced neuronal differentiation and suggest that FoxO3a inhibits NGF-induced neuronal differentiation, at least in part, by suppressing the expression of NCDN.
authors.affiliation: Neuropharmacology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Wang
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Duan
authors.forename: Yannan
authors.initials: Y
authors.lastname: Ren
authors.forename: Yizhi
authors.initials: Y
authors.lastname: Liu
authors.forename: Min
authors.initials: M
authors.lastname: Huang
authors.forename: Peiqing
authors.initials: P
authors.lastname: Liu
authors.forename: Rikang
authors.initials: R
authors.lastname: Wang
authors.forename: Guoquan
authors.initials: G
authors.lastname: Gao
authors.forename: Lihua
authors.initials: L
authors.lastname: Zhou
authors.forename: Zhongping
authors.initials: Z
authors.lastname: Feng
authors.forename: Wenhua
authors.initials: W
authors.lastname: Zheng
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects* / Q000235:genetics; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D020932:Nerve Growth Factor / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D016501:Neurites / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D016716:PC12 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D020932:Nerve Growth Factor; D009419:Nerve Tissue Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C499515:FOXO3 protein, rat; C119189:neurochondrin