The Drosophila microRNA iab-4 causes a dominant homeotic transformation of halteres to wings.

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.

[1]  M. Akam,et al.  Ultrabithorax and the control of cell morphology in Drosophila halteres. , 2000, Development.

[2]  D. Hogness,et al.  Novel transcripts from the Ultrabithorax domain of the bithorax complex. , 1987, Genes & development.

[3]  F. Karch,et al.  Mcp and Fab-7: molecular analysis of putative boundaries of cis-regulatory domains in the bithorax complex of Drosophila melanogaster. , 1994, Nucleic acids research.

[4]  R. Mann,et al.  The developmental and molecular biology of genes that subdivide the body of Drosophila. , 2000, Annual review of cell and developmental biology.

[5]  E. Lewis,et al.  Complete sequence of the bithorax complex of Drosophila. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[6]  M. Wilcox,et al.  Protein products of the bithorax complex in Drosophila , 1984, Cell.

[7]  P. O’Farrell,et al.  Progression of the cell cycle through mitosis leads to abortion of nascent transcripts , 1991, Cell.

[8]  William McGinnis,et al.  Multiplex Detection of RNA Expression in Drosophila Embryos , 2004, Science.

[9]  E. Lewis,et al.  Characterization of the intergenic RNA profile at abdominal-A and Abdominal-B in the Drosophila bithorax complex , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[10]  K. Lindblad-Toh,et al.  Systematic discovery of regulatory motifs in human promoters and 3′ UTRs by comparison of several mammals , 2005, Nature.

[11]  V. Pirrotta,et al.  Chromatin-silencing mechanisms in Drosophila maintain patterns of gene expression. , 1997, Trends in genetics : TIG.

[12]  Eric C Lai,et al.  microRNAs: Runts of the Genome Assert Themselves , 2003, Current Biology.

[13]  Michael Zuker,et al.  MicroRNA-responsive 'sensor' transgenes uncover Hox-like and other developmentally regulated patterns of vertebrate microRNA expression , 2004, Nature Genetics.

[14]  D. Duboule,et al.  The structural and functional organization of the murine HOX gene family resembles that of Drosophila homeotic genes. , 1989, The EMBO journal.

[15]  F. Karch,et al.  abdA expression in Drosophila embryos. , 1990, Genes & development.

[16]  N. Patel,et al.  Functional analysis of eve stripe 2 enhancer evolution in Drosophila: rules governing conservation and change. , 1998, Development.

[17]  Julius Brennecke,et al.  Identification of Drosophila MicroRNA Targets , 2003, PLoS biology.

[18]  Gerald M Rubin,et al.  Pervasive regulation of Drosophila Notch target genes by GY-box-, Brd-box-, and K-box-class microRNAs. , 2005, Genes & development.

[19]  F. Karch,et al.  The Fab-8 boundary defines the distal limit of the bithorax complex iab-7 domain and insulates iab-7 from initiation elements and a PRE in the adjacent iab-8 domain. , 2000, Development.

[20]  Robert A. Drewell,et al.  Transcription defines the embryonic domains of cis-regulatory activity at the Drosophila bithorax complex , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[21]  C. Burge,et al.  Conserved Seed Pairing, Often Flanked by Adenosines, Indicates that Thousands of Human Genes are MicroRNA Targets , 2005, Cell.

[22]  Peter F Stadler,et al.  Evolution of microRNAs located within Hox gene clusters. , 2005, Journal of experimental zoology. Part B, Molecular and developmental evolution.

[23]  E. Sánchez-Herrero,et al.  Genetic organization of Drosophila bithorax complex , 1985, Nature.

[24]  Y. T. Kim,et al.  Effects of Polycomb Group Mutations on the Expression of Ultrabithorax in the Drosophila Visceral Mesoderm , 2000, Molecules and cells.

[25]  D. Bartel,et al.  MicroRNA-Directed Cleavage of HOXB8 mRNA , 2004, Science.

[26]  E. Lewis.  A gene complex controlling segmentation in Drosophila , 1978, Nature.

[27]  R. Russell,et al.  bantam Encodes a Developmentally Regulated microRNA that Controls Cell Proliferation and Regulates the Proapoptotic Gene hid in Drosophila , 2003, Cell.

[28]  D. Marks,et al.  The small RNA profile during Drosophila melanogaster development. , 2003, Developmental cell.

[29]  M. Levine,et al.  The Fab-7 element of the bithorax complex attenuates enhancer-promoter interactions in the Drosophila embryo. , 1996, Genes & development.

[30]  P. Avner,et al.  The role of antisense transcription in the regulation of X-inactivation. , 2004, Current topics in developmental biology.

[31]  R. Russell,et al.  Principles of MicroRNA–Target Recognition , 2005, PLoS biology.

[32]  S. Cumberledge,et al.  Characterization of two RNAs transcribed from the cis-regulatory region of the abd-A domain within the Drosophila bithorax complex. , 1990, Proceedings of the National Academy of Sciences of the United States of America.

[33]  Anton J. Enright,et al.  MicroRNA targets in Drosophila , 2003, Genome Biology.

[34]  T. Tuschl,et al.  Identification of Novel Genes Coding for Small Expressed RNAs , 2001, Science.

[35]  D. Bartel.  MicroRNAs Genomics, Biogenesis, Mechanism, and Function , 2004, Cell.

[36]  Kristin C. Gunsalus,et al.  microRNA Target Predictions across Seven Drosophila Species and Comparison to Mammalian Targets , 2005, PLoS Comput. Biol..

[37]  S. Carroll,et al.  Ultrabithorax regulates genes at several levels of the wing-patterning hierarchy to shape the development of the Drosophila haltere. , 1998, Genes & development.

[38]  R. Aharonov,et al.  Identification of hundreds of conserved and nonconserved human microRNAs , 2005, Nature Genetics.

[39]  E. Lai.  Micro RNAs are complementary to 3′ UTR sequence motifs that mediate negative post-transcriptional regulation , 2002, Nature Genetics.