Rap-GEF signaling controls stem cell anchoring to their niche through regulating DE-cadherin-mediated cell adhesion in the Drosophila testis

Dev Cell. 2006 Jan;10(1):117-26. doi: 10.1016/j.devcel.2005.11.004.


Stem cells will undergo self-renewal to produce new stem cells if they are maintained in their niches. The regulatory mechanisms that recruit and maintain stem cells in their niches are not well understood. In Drosophila testes, a group of 12 nondividing somatic cells, called the hub, identifies the stem cell niche by producing the growth factor Unpaired (Upd). Here, we show that Rap-GEF/Rap signaling controls stem cell anchoring to the niche through regulating DE-cadherin-mediated cell adhesion. Loss of function of a Drosophila Rap-GEF (Gef26) results in loss of both germline and somatic stem cells. The Gef26 mutation specifically impairs adherens junctions at the hub-stem cell interface, which results in the stem cells "drifting away" from the niche and losing stem cell identity. Thus, the Rap signaling/E-cadherin pathway may represent one mechanism that regulates polarized niche formation and stem cell anchoring.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Cadherins / metabolism*
  • Cell Adhesion / physiology
  • Cell Adhesion Molecules, Neuronal / metabolism
  • Cloning, Molecular / methods
  • DEAD-box RNA Helicases
  • Drosophila
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism
  • Drosophila Proteins / physiology*
  • Embryo, Nonmammalian
  • ErbB Receptors / metabolism
  • Green Fluorescent Proteins / metabolism
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / physiology*
  • Immunohistochemistry / methods
  • In Situ Hybridization / methods
  • Male
  • Models, Biological
  • Mutation / genetics
  • RNA Helicases / metabolism
  • STAT Transcription Factors / metabolism
  • Signal Transduction / physiology*
  • Stem Cells / physiology*
  • Testis / cytology*


  • Cadherins
  • Cell Adhesion Molecules, Neuronal
  • Drosophila Proteins
  • Fas3 protein, Drosophila
  • Guanine Nucleotide Exchange Factors
  • STAT Transcription Factors
  • Green Fluorescent Proteins
  • ErbB Receptors
  • vas protein, Drosophila
  • DEAD-box RNA Helicases
  • RNA Helicases