A Temporal Signature of Epidermal Growth Factor Signaling Regulates the Differentiation of Germline Cells in Testes of Drosophila Melanogaster

PLoS One. 2013 Aug 5;8(8):e70678. doi: 10.1371/journal.pone.0070678. Print 2013.

Abstract

Tissue replenishment from stem cells follows a precise cascade of events, during which stem cell daughters first proliferate by mitotic transit amplifying divisions and then enter terminal differentiation. Here we address how stem cell daughters are guided through the early steps of development. In Drosophila testes, somatic cyst cells enclose the proliferating and differentiating germline cells and the units of germline and surrounding cyst cells are commonly referred to as cysts. By characterizing flies with reduced or increased Epidermal Growth Factor (EGF) signaling we show that EGF triggers different responses in the cysts dependent on its dose. In addition to the previously reported requirement for EGF signaling in cyst formation, a low dose of EGF signaling is required for the progression of the germline cells through transit amplifying divisions, and a high dose of EGF signaling promotes terminal differentiation. Terminal differentiation was promoted in testes expressing a constitutively active EGF Receptor (EGFR) and in testes expressing both a secreted EGF and the EGFR in the cyst cells, but not in testes expressing either only EGF or only EGFR. We propose that as the cysts develop, a temporal signature of EGF signaling is created by the coordinated increase of both the production of active ligands by the germline cells and the amount of available receptor molecules on the cyst cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation*
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / cytology*
  • Drosophila melanogaster / metabolism
  • Epidermal Growth Factor / physiology*
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism*
  • Gene Expression
  • Male
  • Spermatocytes / physiology
  • Spermatogenesis
  • Spermatogonia / physiology*
  • Testis / cytology*

Substances

  • Drosophila Proteins
  • Epidermal Growth Factor
  • ErbB Receptors

Grant support

The work was supported by a grant from the American Foundation for Aging Research given to B.B.P. (no grant #), and start-up funds from University of Georgia, Athens, and NSF grant #0841419 given to C.S. The funders have no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.