title: Microarray analysis of microRNA expression in the developing mammalian brain.
abstract: BACKGROUND
  MicroRNAs are a large new class of tiny regulatory RNAs found in nematodes, plants, insects and mammals. MicroRNAs are thought to act as post-transcriptional modulators of gene expression. In invertebrates microRNAs have been implicated as regulators of developmental timing, neuronal differentiation, cell proliferation, programmed cell death and fat metabolism. Little is known about the roles of microRNAs in mammals.
  
  
  RESULTS
  We isolated 18-26 nucleotide RNAs from developing rat and monkey brains. From the sequences of these RNAs and the sequences of the rat and human genomes we determined which of these small RNAs are likely to have derived from stem-loop precursors typical of microRNAs. Next, we developed a microarray technology suitable for detecting microRNAs and printed a microRNA microarray representing 138 mammalian microRNAs corresponding to the sequences of the microRNAs we cloned as well as to other known microRNAs. We used this microarray to determine the profile of microRNAs expressed in the developing mouse brain. We observed a temporal wave of expression of microRNAs, suggesting that microRNAs play important roles in the development of the mammalian brain.
  
  
  CONCLUSIONS
  We describe a microarray technology that can be used to analyze the expression of microRNAs and of other small RNAs. MicroRNA microarrays offer a new tool that should facilitate studies of the biological roles of microRNAs. We used this method to determine the microRNA expression profile during mouse brain development and observed a temporal wave of gene expression of sequential classes of microRNAs.
authors.affiliation: Howard Hughes Medical Institute, Department of Biology and McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. miska@mit.edu
authors.forename: Eric A
authors.initials: EA
authors.lastname: Miska
authors.forename: Ezequiel
authors.initials: E
authors.lastname: Alvarez-Saavedra
authors.forename: Matthew
authors.initials: M
authors.lastname: Townsend
authors.forename: Akira
authors.initials: A
authors.lastname: Yoshii
authors.forename: Nenad
authors.initials: N
authors.lastname: Sestan
authors.forename: Pasko
authors.initials: P
authors.lastname: Rakic
authors.forename: Martha
authors.initials: M
authors.lastname: Constantine-Paton
authors.forename: H Robert
authors.initials: HR
authors.lastname: Horvitz
mesh_terms: D000818:Animals; D015152:Blotting, Northern / Q000379:methods; D001921:Brain / Q000196:embryology* / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D020869:Gene Expression Profiling / Q000379:methods; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D006801:Humans; D008253:Macaca mulatta / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics*; D046228:Microarray Analysis / Q000379:methods*; D015347:RNA Probes / Q000235:genetics; D018075:RNA, Complementary / Q000235:genetics; D012342:RNA, Small Nuclear / Q000235:genetics; D051381:Rats; D016415:Sequence Alignment / Q000379:methods; D013995:Time
chemical_list: D035683:MicroRNAs; D015347:RNA Probes; D018075:RNA, Complementary; D012342:RNA, Small Nuclear; C405486:U6 small nuclear RNA