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Differential roles of PtdIns(4,5)P2 and phosphorylation in moesin activation during Drosophila development

Fernando Roch1, Cédric Polesello, Chantal Roubinet

  • 1Université de Toulouse UPS, Centre de Biologie du Développement, Toulouse, France. roch@cict.fr

Journal of Cell Science
|June 4, 2010
PubMed

Insights

Phosphorylation is not essential for moesin protein function in Drosophila development. Phosphatidylinositol (4,5)-bisphosphate binding is crucial for moesin membrane recruitment and subsequent activation.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Developmental Biology

Background:

  • Ezrin, radixin, and moesin (ERM) proteins are key regulators of cell membrane structure.
  • ERM protein activation is thought to involve phosphatidylinositol (4,5)-bisphosphate (PtdIns(4,5)P(2)) binding and threonine phosphorylation.

Purpose of the Study:

  • To investigate the in vivo roles of PtdIns(4,5)P(2) binding and phosphorylation in moesin regulation during Drosophila development.
  • To elucidate the interplay between PtdIns(4,5)P(2) and phosphorylation in orchestrating ERM protein activity.

Main Methods:

  • Utilized Drosophila melanogaster as a model organism.
  • Generated and analyzed a non-phosphorylatable moesin mutant.
  • Assessed moesin function during wing morphogenesis.
  • Investigated moesin membrane recruitment and phosphorylation dynamics.

Main Results:

  • A non-phosphorylatable moesin mutant retained significant activity and could rescue endogenous moesin function during wing development.
  • PtdIns(4,5)P(2) binding was indispensable for moesin recruitment to the plasma membrane.
  • PtdIns(4,5)P(2) binding was necessary for subsequent moesin phosphorylation.
  • Data suggest PtdIns(4,5)P(2) acts as a local regulator of ERM membrane recruitment and activation.

Conclusions:

  • Moesin activation in vivo is not solely dependent on phosphorylation; PtdIns(4,5)P(2) binding plays a critical initial role.
  • PtdIns(4,5)P(2) controls ERM protein localization and initial activation, while phosphorylation/dephosphorylation cycles fine-tune activity at the cell cortex.

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