The Drosophila microRNA iab-4 causes a dominant homeotic transformation of halteres to wings (original) (raw)

  1. Matthew Ronshaugen1,
  2. Frédéric Biemar1,
  3. Jessica Piel1,
  4. Mike Levine1,4, and
  5. Eric C. Lai2,3
  6. 1Department of Molecular and Cell Biology, Division of Genetics, Center for Integrative Genomics, University of California, Berkeley, California 94720, USA; 2Department of Developmental Biology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA

Abstract

The Drosophila Bithorax Complex encodes three well-characterized homeodomain proteins that direct segment identity, as well as several noncoding RNAs of unknown function. Here, we analyze the iab-4 locus, which produces the microRNAs iab-4-5p and iab-4-3p. iab-4 is analogous to miR-196 in vertebrate Hox clusters. Previous studies demonstrate that miR-196 interacts with the Hoxb8 3′ untranslated region. Evidence is presented that miR-iab-4-5p directly inhibits Ubx activity in vivo. Ectopic expression of mir-iab-4-5p attenuates endogenous Ubx protein accumulation and induces a classical homeotic mutant phenotype: the transformation of halteres into wings. These findings provide the first evidence for a noncoding homeotic gene and raise the possibility that other such genes occur within the Bithorax complex. We also discuss the regulation of mir-iab-4 expression during development.

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