An SH3PX1-Dependent Endocytosis-Autophagy Network Restrains Intestinal Stem Cell Proliferation by Counteracting EGFR-ERK Signaling

Dev Cell. 2019 May 20;49(4):574-589.e5. doi: 10.1016/j.devcel.2019.03.029. Epub 2019 Apr 18.


The effect of intracellular vesicle trafficking on stem-cell behavior is largely unexplored. We screened the Drosophila sorting nexins (SNXs) and discovered that one, SH3PX1, profoundly affects gut homeostasis and lifespan. SH3PX1 restrains intestinal stem cell (ISC) division through an endocytosis-autophagy network that includes Dynamin, Rab5, Rab7, Atg1, 5, 6, 7, 8a, 9, 12, 16, and Syx17. Blockages in this network stabilize ligand-activated EGFRs, recycling them via Rab11-dependent endosomes to the plasma membrane. This hyperactivated ERK, calcium signaling, and ER stress, autonomously stimulating ISC proliferation. The excess divisions induced epithelial stress, Yki activity, and Upd3 and Rhomboid production in enterocytes, catalyzing feedforward ISC hyperplasia. Similarly, blocking autophagy increased ERK activity in human cells. Many endocytosis-autophagy genes are mutated in cancers, most notably those enriched in microsatellite instable-high and KRAS-wild-type colorectal cancers. Disruptions in endocytosis and autophagy may provide an alternative route to RAS-ERK activation, resulting in EGFR-dependent cancers.

Keywords: Drosophila sorting nexins; EGFR-Ras-MAPK; Keren; Rab GTPases; SH3PX1; autophagy-related proteins; calcium signaling; colorectal cancer; endocytosis-autophagy network; intestinal stem-cell proliferation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Autophagy / physiology
  • Autophagy-Related Proteins / metabolism
  • Cell Differentiation / physiology
  • Cell Membrane / metabolism
  • Cell Proliferation / physiology
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / cytology*
  • Drosophila melanogaster / metabolism
  • Endocytosis
  • Endosomes / metabolism
  • ErbB Receptors / metabolism*
  • Intestinal Mucosa / cytology*
  • Intestinal Mucosa / metabolism
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • MAP Kinase Signaling System*
  • Protein Transport
  • RNA Polymerase II / genetics
  • RNA Polymerase II / metabolism
  • Receptors, Invertebrate Peptide / metabolism*
  • Signal Transduction / physiology
  • Sorting Nexins / metabolism
  • Stem Cells / cytology*
  • Stem Cells / metabolism
  • rab GTP-Binding Proteins / metabolism


  • Autophagy-Related Proteins
  • Drosophila Proteins
  • Intracellular Signaling Peptides and Proteins
  • Receptors, Invertebrate Peptide
  • SH3PX1 protein, Drosophila
  • Sorting Nexins
  • Egfr protein, Drosophila
  • ErbB Receptors
  • RNA Polymerase II
  • rab GTP-Binding Proteins