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Attribution of vascular phenotypes of the murine Egfl7 locus to the microRNA miR-126

Frank Kuhnert1, Michael R Mancuso, Jessica Hampton

  • 1Division of Hematology, Department of Medicine, Stanford University School of Medicine, CCSR 1155, 269 Campus Drive, Stanford, CA 94305, USA.

Development (Cambridge, England)
|November 7, 2008
PubMed

Insights

MicroRNAs (miRNAs) can complicate mouse knockout studies. This research shows microRNA-126 (miR-126) deletion, not Egfl7 deletion, causes vascular defects, highlighting miRNA dysregulation issues.

Area of Science:

  • Molecular Biology
  • Genetics
  • Developmental Biology

Background:

  • Intronic microRNAs (miRNAs) pose challenges in interpreting gene knockout studies.
  • The Egfl7/miR-126 locus, with miR-126 within Egfl7 intron 7, has been linked to angiogenesis.
  • Previous studies attributed vascular phenotypes to Egfl7 in gene-trap and lacZ knock-in models.

Purpose of the Study:

  • To investigate the distinct roles of Egfl7 and miR-126 in angiogenesis.
  • To clarify the cause of previously observed vascular phenotypes in Egfl7 mutant mice.
  • To assess the impact of miRNA dysregulation in mouse knockout strategies.

Main Methods:

  • Generation of selectively floxed Egfl7 and miR-126 alleles.
  • Phenotypic analysis of Egfl7(Delta/Delta) and miR-126(Delta/Delta) mice.
  • Endothelial-specific deletion studies and adult cornea micropocket assays.
  • Analysis of VEGF-dependent Akt and Erk signaling pathways.

Main Results:

  • Egfl7(Delta/Delta) mice exhibited normal phenotypes.
  • miR-126(Delta/Delta) mice displayed embryonic and postnatal retinal vascular phenotypes similar to previous Egfl7 models.
  • Endothelial miR-126 deletion confirmed its role in regulating angiogenesis.
  • miR-126 deletion inhibited VEGF signaling by derepressing PI3K p85beta and Spred1.

Conclusions:

  • Endothelial miR-126, not Egfl7, is the primary regulator of angiogenesis in this context.
  • Previously reported Egfl7 vascular phenotypes are attributable to miR-126.
  • Inadvertent microRNA dysregulation is a significant complication in mouse knockout study design and interpretation.

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