title: Post-transcriptional regulation of the let-7 microRNA during neural cell specification.
abstract: The let-7 miRNA regulates developmental timing in C. elegans and is an important paradigm for investigations of miRNA functions in mammalian development. We have examined the role of miRNA precursor processing in the temporal control and lineage specificity of the let-7 miRNA. In situ hybridization (ISH) in E9.5 mouse embryos revealed early induction of let-7 in the developing central nervous system. The expression pattern of three let-7 family members closely resembled that of the brain-enriched miRNAs mir-124, mir-125 and mir-128. Comparison of primary, precursor, and mature let-7 RNA levels during both embryonic brain development and neural differentiation of embryonic stem cells and embryocarcinoma (EC) cells suggest post-transcriptional regulation of let-7 accumulation. Reflecting these results, let-7 sensor constructs were strongly down-regulated during neural differentiation of EC cells and displayed lineage specificity in primary cells. Neural differentiation of EC cells was accompanied by an increase in let-7 precursor processing activity in vitro. Furthermore, undifferentiated and differentiated cells contained distinct precursor RNA binding complexes. A neuron-enhanced binding complex was shown by antibody challenge to contain the miRNA pathway proteins Argonaute1 and FMRP. Developmental regulation of the processing pathway correlates with differential localization of the proteins Argonaute, FMRP, MOV10, and TNRC6B in self-renewing stem cells and neurons.
authors.affiliation: Center for Anatomy, Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Schumannstrasse 20-21, 10098 Berlin, Germany. gregory.wulczyn@charite.de
authors.forename: F Gregory
authors.initials: FG
authors.lastname: Wulczyn
authors.forename: Lena
authors.initials: L
authors.lastname: Smirnova
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Rybak
authors.forename: Christine
authors.initials: C
authors.lastname: Brandt
authors.forename: Erik
authors.initials: E
authors.lastname: Kwidzinski
authors.forename: Olaf
authors.initials: O
authors.lastname: Ninnemann
authors.forename: Michael
authors.initials: M
authors.lastname: Strehle
authors.forename: Andrea
authors.initials: A
authors.lastname: Seiler
authors.forename: Stefan
authors.initials: S
authors.lastname: Schumacher
authors.forename: Robert
authors.initials: R
authors.lastname: Nitsch
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D017403:In Situ Hybridization; D051379:Mice; D035683:MicroRNAs / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D035683:MicroRNAs