Post-transcriptional repression of the Drosophila midkine and pleiotrophin homolog miple by HOW is essential for correct mesoderm spreading

Hila Toledano-Katchalski, Ronit Nir, Gloria Volohonsky, Talila Volk

Research output: Contribution to journalArticlepeer-review


The even spreading of mesoderm cells in the Drosophila embryo is essential for its proper patterning by ectodermally derived signals. In how germline clone embryos, defects in mesoderm spreading lead to a partial loss of dorsal mesoderm derivatives. HOW is an RNA-binding protein that is thought to regulate diverse mRNA targets. To identify direct HOW targets, we implemented a series of selection methods on mRNAs whose levels were elevated in how germline clone embryos during the stage of mesoderm spreading. Four mRNAs were found to be specifically elevated in the mesoderm of how germline clone embryos, and to exhibit specific binding to HOW via their 3′ UTRs. Importantly, overexpression of three of these genes phenocopied the mesoderm-spreading phenotype of how germline clone embryos. Further analysis showed that overexpressing one of these genes, miple (a Drosophila midkine and pleiotrophin heparin-binding growth factor), in the mesoderm led to abnormal scattered MAPK activation, a phenotype that might explain the abnormal mesoderm spreading. In addition, the number of EVE-positive cells, which are responsive to receptor tyrosine kinase (RTK) signaling, was increased following Miple overexpression in the mesoderm and appeared to be dependent on Heartless function. In summary, our analysis suggests that HOW downregulates the levels of a number of mRNA species in the mesoderm in order to enable proper mesoderm spreading during early embryogenesis.

Original languageEnglish
Pages (from-to)3473-3481
Number of pages9
JournalDevelopment (Cambridge)
Issue number19
StatePublished - Oct 2007
Externally publishedYes


  • Drosophila
  • HOW
  • HTL
  • Mesoderm
  • Miple
  • RNA regulation

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology


Dive into the research topics of 'Post-transcriptional repression of the Drosophila midkine and pleiotrophin homolog miple by HOW is essential for correct mesoderm spreading'. Together they form a unique fingerprint.

Cite this