Somatic ERK activation during transit amplification is essential for maintaining the synchrony of germline divisions in Drosophila testis

Open Biol. 2018 Jul;8(7):180033. doi: 10.1098/rsob.180033.

Abstract

Transit amplification (TA) of progenitor cells maintains tissue homeostasis by balancing proliferation and differentiation. In Drosophila testis, the germline proliferation is tightly regulated by factors present in both the germline and the neighbouring somatic cyst cells (SCCs). Although the exact mechanism is unclear, the epidermal growth factor receptor (EGFR) activation in SCCs has been reported to control spermatogonial divisions within a cyst, through downstream activations of Rac1-dependent pathways. Here, we report that somatic activation of the mitogen-activated protein kinase (Rolled/ERK) downstream of EGFR is required to synchronize the mitotic divisions and regulate the transition to meiosis. The process operates independently of the Bag-of-marble activity in the germline. Also, the integrity of the somatic cyst enclosure is inessential for this purpose. Together, these results suggest that synchronization of germ-cell divisions through somatic activation of distinct ERK-downstream targets independently regulates TA and subsequent differentiation of neighbouring germline cells.

Keywords: Drosophila; EGFR; ERK; spermatogonia; testis; transit amplification.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult Stem Cells / cytology
  • Adult Stem Cells / metabolism
  • Animals
  • Cell Differentiation
  • Cell Division
  • Cell Proliferation
  • Drosophila / metabolism
  • Drosophila / physiology*
  • Drosophila Proteins / metabolism*
  • ErbB Receptors / metabolism*
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Male
  • Meiosis
  • Mitosis
  • Receptors, Invertebrate Peptide / metabolism*
  • Stem Cells / cytology
  • Testis / metabolism
  • Testis / physiology*

Substances

  • Drosophila Proteins
  • Receptors, Invertebrate Peptide
  • bam protein, Drosophila
  • Egfr protein, Drosophila
  • ErbB Receptors
  • Extracellular Signal-Regulated MAP Kinases
  • rl protein, Drosophila