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The initial step of bone digestion is the adhesion of osteoclasts onto bone surfaces and the assembly of podosomal belts that segregate the bone-facing ruffled membrane from other membrane domains. During bone digestion, membrane components of the ruffled border also need to be recycled after macropinocytosis of digested bone materials. How osteoclast polarity and membrane recycling are coordinated remains unknown. Here, we show that the Cdc42-guanine nucleotide exchange factor FGD6 coordinates these events through its Src-dependent interaction with different actin-based protein networks. At the plasma membrane, FGD6 couples cell adhesion and actin dynamics by regulating podosome formation through the assembly of complexes comprising the Cdc42-interactor IQGAP1, the Rho GTPase-activating protein ARHGAP10, and the integrin interactors Talin-1/2 or Filamin A. On endosomes and transcytotic vesicles, FGD6 regulates retromer-dependent membrane recycling through its interaction with the actin nucleation-promoting factor WASH. These results provide a mechanism by which a single Cdc42-exchange factor controlling different actin-based processes coordinates cell adhesion, cell polarity, and membrane recycling during bone degradation.

Original publication

DOI

10.1074/jbc.M113.504894

Type

Journal article

Journal

J biol chem

Publication Date

27/06/2014

Volume

289

Pages

18347 - 18359

Keywords

Actin, CDC42, FGD6, Membrane Recycling, Osteoclast, Podosome, Src, Animals, Bone and Bones, Cell Adhesion, Cell Line, Cell Polarity, Endosomes, Guanine Nucleotide Exchange Factors, Intracellular Membranes, Mice, Osteoclasts, Protein Binding, cdc42 GTP-Binding Protein