EGFR/Ras Signaling Controls Drosophila Intestinal Stem Cell Proliferation via Capicua-Regulated Genes

PLoS Genet. 2015 Dec 18;11(12):e1005634. doi: 10.1371/journal.pgen.1005634. eCollection 2015 Dec.

Abstract

Epithelial renewal in the Drosophila intestine is orchestrated by Intestinal Stem Cells (ISCs). Following damage or stress the intestinal epithelium produces ligands that activate the epidermal growth factor receptor (EGFR) in ISCs. This promotes their growth and division and, thereby, epithelial regeneration. Here we demonstrate that the HMG-box transcriptional repressor, Capicua (Cic), mediates these functions of EGFR signaling. Depleting Cic in ISCs activated them for division, whereas overexpressed Cic inhibited ISC proliferation and midgut regeneration. Epistasis tests showed that Cic acted as an essential downstream effector of EGFR/Ras signaling, and immunofluorescence showed that Cic's nuclear localization was regulated by EGFR signaling. ISC-specific mRNA expression profiling and DNA binding mapping using DamID indicated that Cic represses cell proliferation via direct targets including string (Cdc25), Cyclin E, and the ETS domain transcription factors Ets21C and Pointed (pnt). pnt was required for ISC over-proliferation following Cic depletion, and ectopic pnt restored ISC proliferation even in the presence of overexpressed dominant-active Cic. These studies identify Cic, Pnt, and Ets21C as critical downstream effectors of EGFR signaling in Drosophila ISCs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Proliferation / genetics
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics*
  • Drosophila / genetics
  • Drosophila Proteins / biosynthesis
  • Drosophila Proteins / genetics*
  • ErbB Receptors / genetics*
  • Gene Expression Regulation, Developmental
  • HMGB Proteins / biosynthesis
  • HMGB Proteins / genetics*
  • Intestines / cytology
  • Intestines / growth & development
  • Nerve Tissue Proteins / biosynthesis
  • Nerve Tissue Proteins / genetics*
  • Proto-Oncogene Proteins / biosynthesis
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins c-ets / genetics*
  • RNA, Messenger / biosynthesis
  • Receptors, Invertebrate Peptide / genetics*
  • Repressor Proteins / biosynthesis
  • Repressor Proteins / genetics*
  • Signal Transduction / genetics
  • Stem Cells / cytology
  • Transcription Factors / biosynthesis
  • Transcription Factors / genetics*

Substances

  • DNA-Binding Proteins
  • Drosophila Proteins
  • Ets21C protein, Drosophila
  • HMGB Proteins
  • Nerve Tissue Proteins
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-ets
  • RNA, Messenger
  • Receptors, Invertebrate Peptide
  • Repressor Proteins
  • Transcription Factors
  • cic protein, Drosophila
  • pnt protein, Drosophila
  • Egfr protein, Drosophila
  • ErbB Receptors

Grant support

This work was supported by the DKFZ, DFG grant SFB 873, and ERC Advanced Grant 268515 (http://erc.europa.eu/starting-grants) to BAE. NH was supported by SFB638, SFB1036. MF and GJ were supported by research grants from the Spanish Government (BFU2011-23611) and Fundació La Marató de TV3 (20131730); GJ is an ICREA investigator.The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.