title: A novel role for FAK as a protease-targeting adaptor protein: regulation by p42 ERK and Src.
abstract: Cell migration on extracellular matrix requires the turnover of integrin-dependent adhesions. The nonreceptor tyrosine kinases Src and FAK regulate focal-adhesion turnover by poorly understood mechanisms. ERK/MAP kinase-mediated activation of the protease Calpain 2 also promotes focal-adhesion turnover; however, it is not known if this is linked to the activities of Src and FAK. Calpain 2 has previously been demonstrated to colocalize with focal-adhesion structures and can cleave several focal-adhesion complex components, including FAK. Studies utilizing Calpain inhibitors or Calpain-deficient cells confirm that Calpain's role in regulating focal-adhesion turnover is necessary for cell migration. We have identified a novel and kinase-independent function for FAK as an adaptor molecule that mediates the assembly of a complex consisting of at least Calpain 2 and p42ERK. Mutation of proline residues (Pro2) in the amino-terminal region of FAK blocks direct binding with Calpain 2 and also prevents formation of the Calpain 2/p42ERK complex in cells. We show that both complex formation and MEK/ERK activity are associated with Calpain-mediated proteolysis of FAK and focal adhesion turnover during transformation and migration. Furthermore, FAK is necessary for recruiting both Calpain 2 and p42ERK/MAPK to peripheral adhesion sites facilitating maximal Calpain activity.
authors.affiliation: The Beatson Institute for Cancer Research, Cancer Research United Kingdom, Beatson Laboratories, Glasgow G61 1BD, Scotland, United Kingdom. n.carragher@beatson.gla.ac.uk
authors.forename: Neil O
authors.initials: NO
authors.lastname: Carragher
authors.forename: M Andrew
authors.initials: MA
authors.lastname: Westhoff
authors.forename: Valerie J
authors.initials: VJ
authors.lastname: Fincham
authors.forename: Michael D
authors.initials: MD
authors.lastname: Schaller
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Frame
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002154:Calpain / Q000378:metabolism; D002465:Cell Movement; D002478:Cells, Cultured; D002642:Chick Embryo; D051416:Focal Adhesion Protein-Tyrosine Kinases; D022001:Focal Adhesions; D018390:Gene Targeting; D046911:Macromolecular Substances; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D011392:Proline / Q000737:chemistry; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014170:Transformation, Genetic; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D046911:Macromolecular Substances; D011392:Proline; D011505:Protein-Tyrosine Kinases; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019061:src-Family Kinases; D019950:Mitogen-Activated Protein Kinase 1; D002154:Calpain