title: Reduction of Dicer impairs Schwann cell differentiation and myelination.
abstract: The process of Schwann cell myelination requires precisely coordinated gene expression. At the onset of myelination, there is an increase in the expression of differentiation-promoting transcription factors that regulate key Schwann cell genes. Further control of myelin gene expression occurs at the posttranscriptional level and, in part, is mediated by RNA binding proteins and micro-RNAs (miRNAs). miRNAs are small, endogenously derived RNA molecules that repress gene expression by specifically binding to their mRNA targets. In the experiments described here, we tested whether miRNAs were essential in controlling myelination by reducing the levels of Dicer, an essential endoribonuclease in miRNA biogenesis. We decreased the expression of Dicer by about 60% within Schwann cells using a lentiviral vector expressing an shRNA against Dicer. The reduced levels of Dicer led to a decrease in the steady-state expression of selected miRNAs and of the transcription factors Oct6 and Egr2/Krox20, both of which are critical for Schwann cells differentiation and myelination. In contrast, the levels of c-jun and Sox2 were up-regulated by the reduction in Dicer and were associated with an increase in Schwann cell proliferation. In dorsal root ganglion cocultures, Schwann cells transduced with Dicer shRNA synthesized less myelin, which was accompanied by significant reductions in the levels of myelin basic protein and protein zero. These findings support a critical role for Dicer and miRNAs in Schwann cell differentiation and myelination.
authors.affiliation: Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida 32610-0244, USA.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Verrier
authors.forename: Susan
authors.initials: S
authors.lastname: Semple-Rowland
authors.forename: Irina
authors.initials: I
authors.lastname: Madorsky
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Papin
authors.forename: Lucia
authors.initials: L
authors.lastname: Notterpek
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D018920:Coculture Techniques; D015536:Down-Regulation / Q000502:physiology; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics*; D009186:Myelin Sheath / Q000378:metabolism* / Q000502:physiology; D034622:RNA Interference / Q000502:physiology; D051381:Rats; D043244:Ribonuclease III / Q000235:genetics* / Q000378:metabolism*; D012583:Schwann Cells / Q000166:cytology / Q000378:metabolism*; D011984:Sensory Receptor Cells / Q000166:cytology / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology
chemical_list: D035683:MicroRNAs; D043244:Ribonuclease III