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The tumor suppressors Merlin and Expanded function cooperatively to modulate receptor endocytosis and signaling

Sushmita Maitra1, Rima M Kulikauskas, Heather Gavilan

  • 1Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637, USA.

Current Biology : CB
|April 4, 2006
PubMed

Insights

The Drosophila tumor suppressors Merlin (Mer) and Expanded (ex) regulate cell proliferation by controlling cell-surface receptor levels. Loss of Mer and ex leads to hyperactivated signaling pathways due to defective receptor clearance.

Area of Science:

  • Cell Biology
  • Developmental Biology
  • Molecular Biology

Background:

  • Precise signal coordination is crucial for tissue growth regulation.
  • Receptor localization, compartmentalization, and trafficking significantly impact signaling in developing tissues.
  • The roles of Merlin (Mer) and Expanded (ex) in regulating proliferation and differentiation in imaginal epithelia are investigated.

Purpose of the Study:

  • To elucidate the mechanism by which Drosophila tumor suppressors Merlin and Expanded regulate proliferation and differentiation.
  • To understand how these FERM domain proteins affect signaling and adhesion receptors.
  • To investigate the impact of Merlin and Expanded on receptor turnover and cell surface dynamics.

Main Methods:

  • Examined the mechanism of Merlin and Expanded in Drosophila imaginal epithelia.
  • Assessed the steady-state levels of signaling and adhesion receptors.
  • Utilized pulse-chase labeling of Notch in living tissues to study receptor turnover.

Main Results:

  • Merlin and Expanded regulate steady-state levels of signaling and adhesion receptors.
  • Loss of Merlin and Expanded leads to hyperactivation of associated signaling pathways.
  • Mer; ex double mutant cells exhibit upregulated cell-surface receptor levels due to impaired receptor clearance.

Conclusions:

  • Merlin and Expanded control tissue proliferation by regulating the abundance, localization, and turnover of cell-surface receptors.
  • Misregulation of these receptor dynamics is implicated in tumorigenesis.
  • These findings provide insights into the molecular mechanisms underlying growth control and cancer development.

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