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Gem associates with Ezrin and acts via the Rho-GAP protein Gmip to down-regulate the Rho pathway

Anastassia Hatzoglou1, Isabelle Ader, Anne Splingard

  • 1Institut Curie-Centre de Recherche and Inserm U528, Paris F-75248, France. hatzoglo@cict.fr

Molecular Biology of the Cell
|February 3, 2007
PubMed

Insights

Gem protein binds active Ezrin, a membrane-cytoskeleton linker, influencing cell shape. This interaction, mediated by Gmip, down-regulates RhoA pathway activity, affecting actin stress fibers and focal adhesions.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Gem, a Ras superfamily protein, regulates Ca2+ channels and cytoskeletal organization.
  • Ezrin is a key membrane-cytoskeleton linker protein involved in cell structure.
  • The Rho pathway is crucial for regulating actin dynamics and cell adhesion.

Purpose of the Study:

  • To investigate the interaction between Gem and Ezrin.
  • To elucidate the mechanism by which Gem influences cytoskeletal organization.
  • To determine the role of Gem in regulating the RhoA pathway.

Main Methods:

  • Coexpression of Gem and Ezrin in cells.
  • Analysis of cell morphology, actin stress fibers, and focal adhesions.
  • Investigation of RhoA activity and ERM protein phosphorylation.
  • Assessment of Gem's interaction with Ezrin and Gmip.

Main Results:

  • GTP-bound Gem interacts with active Ezrin at the plasma membrane-cytoskeleton interface.
  • Coexpression of Gem and Ezrin induces cell elongation, loss of actin stress fibers, and focal adhesion collapse.
  • Gem down-regulates active RhoA and actin stress fibers.
  • Gem's effects are mediated by its Rho-GAP partner, Gmip, and require ERM proteins.

Conclusions:

  • Gem binds active Ezrin to regulate cytoskeletal organization.
  • Gem utilizes Gmip to inhibit RhoA-dependent processes, including ERM phosphorylation and cytoskeletal rearrangements.
  • Gem plays a significant role in controlling cell shape and adhesion through the Rho pathway.

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