Book of Abstracts: Albany 2003

category image Albany 2003
Conversation 13
Abstract Book
June 17-21 2003

Small Interfering RNAs and MicroRNAs in Animal Systems

RNA interference (RNAi) represents an evolutionary conserved cellular defense mechanism for controlling the expression of alien genes in protists, filamentous fungi, plants, animals and humans. RNAi is triggered by double-stranded RNA (dsRNA) and causes sequence-specific degradation of homologous mRNAs. The mediators of target RNA cleavage are duplexes of 21-nt small interfering RNAs (siRNAs) produced by Dicer RNAse III cleavage of long dsRNAs or RNA hairpins (1). Duplexes of 21-nt siRNAs with symmetric 2-nt 3' overhangs or RNA hairpins with a single 2-nt 3'-overhang are efficient triggers of RNAi in mammalian cells siRNAs and hairpin RNAs of less than 30 base pairs do not trigger sequence-unspecific effects in mammalian cells (interferon response) and produce ?knockdown? cells with characteristic ?knockdown? phenotypes (2). We are characterizing the human ribonucleoprotein complexes involved in RNAi and recently showed the participation of the human Argonaute family members, eIF2C1 and eIF2C2, in the formation of the target RNA-cleaving RNA-induced silencing complex (RISC) (3). Active RISC contains a single-stranded antisense RNA that guides the target RNA cleavage.

Another class of small regulatory RNAs has been identified from cloning of small expressed RNAs from total RNA preparations. These microRNAs represent an extensive class of evolutionary conserved noncoding RNAs. Mature miRNAs are about 22 nucleotide in length and excised from stem-loop precursors of about 60 nucleotide in length. In contrast to siRNAs that are complementary to their target mRNAs, animal miRNAs appear to be only partially complementary and are believed to act predominantly as translational regulators. The characterization of miRNAs from Drosophila melanogaster indicated that there is a third species of small RNAs of about 25 nucleotide in length derived from double-stranded RNA of retrotransposable elements.

Javier Martinez1
Agnieszka Patkaniowska1
Mariana Lagos-Quintana1
Jutta Meyer1
Alexei Aravin2
Sayda M. Elbashir3
Jens Harborth3
Klaus Weber4
Abdullah Yalcin5
Henning Urlaub5
Reinhard Rauhut5
Reinhard Luehrmann5
Thomas Tuschl1,*

1Laboratory for RNA Molecular Biology
Rockefeller University
1230 York Avenue
New York, NY 10021
2Department of Animal Molecular Genetics
Institute of Molecular Genetics
Moscow 123182
3Alnylam Pharmaceuticals
790 Memorial Drive
Suite 202
Cambridge, MA 02139
4Department of Cellular Biochemistry
5Department of Biochemistry and Cell Biology
Max Planck Institute for Biophysical Chemistry
Am Fassberg 11
37077 Goettingen, Germany

References and Footnotes
  1. Elbashir, S. M., Lendeckel, W., Tuschl, T. Genes Dev, 15, 188-200 (2001).
  2. Elbashir, S. M., Harborth, J., Lendeckel, W., Yalcin, A., Weber, K., Tuschl, T. Nature, 411, 494-498 (2001).
  3. Martinez, J., Patkaniowska, A., Urlaub, H., Luehrmann, R., Tuschl, T. Cell, 110, 563-574 (2002).
  4. Lagos-Quintana, M., Rauhut, R., Lendeckel, W., Tuschl, T. Science, 294, 853-858 (2001).
  5. Lau, N. C., Lim, L.P., Weinstein, E.G., Bartel, D.P. Science, 294, 858-862 (2001).
  6. Lee, R. C., Ambros, V. Science, 294, 862-864 (2001).