title: Expression of the repressor element-1 silencing transcription factor (REST) is influenced by insulin-like growth factor-I in differentiating human neuroblastoma cells.
abstract: The repressor element-1 (RE-1) silencing transcription factor (REST) interacts with an RE-1 cis element and represses the transcription of neuron-specific genes in neuronal progenitors but is down-regulated in post-mitotic neurons. We report that REST expression is modified, in a time-dependent manner, in SH-SY5Y neuroblastoma cells exposed to insulin-like growth factor I (IGF-I), a polypeptide hormone affecting various aspects of neuronal induction and maturation. REST is increased in cells treated with IGF-I for 2 days and then declines in 5-day-treated cells concomitant with a progressive neurite extension. To investigate any role played by REST in neurodifferentiation by IGF-I, we employed an antisense oligonucleotide (AS-ODN) complementary to REST mRNA. In AS-ODN-treated cells, the effects elicited by IGF-I on cell proliferation are not influenced whereas a marked decrease of REST significantly increases neurite elongation without any gross perturbation of neurogenesis. Synapsin I and betaIII-tubulin gene promoters contain an RE-1 motif and their transcription is repressed by REST; both of them are increased in cells exposed to IGF-I for 5 days and further elevated by AS-ODN treatment. A parallel increase of growth cone-associated protein 43, a protein chosen as a neuronal marker not directly regulated by REST, is also observed. Therefore, REST is elevated during early steps of neural induction by IGF-I and could contribute to down-regulate genes not yet required by the differentiation program while it declines later for the acquisition of neural phenotypes. These results suggest a model in which differentiating neuroblastoma cells determine their extent of neurite outgrowth on the basis of REST disappearance.
authors.affiliation: Department of Pharmacology, University of Bologna, Irnerio 48, 40126 Bologna, Italy.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Di Toro
authors.forename: Monica
authors.initials: M
authors.lastname: Baiula
authors.forename: Santi
authors.initials: S
authors.lastname: Spampinato
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D015153:Blotting, Western / Q000379:methods; D002454:Cell Differentiation / Q000187:drug effects* / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004347:Drug Interactions; D024202:Electrophoretic Mobility Shift Assay / Q000379:methods; D004789:Enzyme Activation / Q000187:drug effects; D019922:GAP-43 Protein / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016501:Neurites / Q000187:drug effects; D009447:Neuroblastoma; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D016704:Synapsins / Q000378:metabolism; D013936:Thymidine / Q000493:pharmacokinetics; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014316:Tritium / Q000493:pharmacokinetics; D014404:Tubulin / Q000378:metabolism; D000099229:RE1-Silencing Transcription Factor
chemical_list: D000906:Antibodies; D016895:Culture Media, Serum-Free; D019922:GAP-43 Protein; D007334:Insulin-Like Growth Factor I; D020928:Mitogen-Activated Protein Kinases; D020319:Oligodeoxyribonucleotides, Antisense; D012333:RNA, Messenger; D012097:Repressor Proteins; D016704:Synapsins; D013936:Thymidine; D014157:Transcription Factors; D014316:Tritium; D014404:Tubulin; D000099229:RE1-Silencing Transcription Factor