Abstract
Hepatocyte growth factor (HGF) signaling via its receptor, the proto-oncogene Met, alters cell proliferation and motility and has been associated with tumor metastasis. HGF treatment of HepG2 human hepatocellular carcinoma cells induces cell migration concomitant with increased levels of the p27(kip1) cyclin-cdk inhibitor. HGF signaling resulted in nuclear export of endogenous p27 to the cytoplasm, via Ser-10 phosphorylation, where it colocalized with F-actin. Introduction of transducible p27 protein (TATp27) was sufficient for actin cytoskeletal rearrangement and migration of HepG2 cells. TATp27 mutational analysis identified a novel p27 C-terminal domain required for cell migration, distinct from the N-terminal cyclin-cyclin-dependent kinase (cdk) binding domain. Loss or disruption of the p27 C-terminal domain abolished both actin rearrangement and cell migration. The cell-scattering activity of p27 occurred independently of its cell cycle arrest functions and required cytoplasmic localization of p27 via Ser-10 phosphorylation. Furthermore, Rac GTPase was necessary for p27-dependent migration but alone was insufficient for HepG2 cell migration. These results predicted a migration defect in p27-deficient cells. Indeed, p27-deficient primary fibroblasts failed to migrate, and reconstitution with TATp27 rescued the motility defect. These observations define a novel role for p27 in cell motility that is independent of its function in cell cycle inhibition.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Actins / metabolism
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Actins / ultrastructure
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Amino Acid Sequence
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CDC2-CDC28 Kinases*
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Carcinoma, Hepatocellular / drug therapy
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Carcinoma, Hepatocellular / metabolism
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Carcinoma, Hepatocellular / pathology
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Cell Cycle / drug effects
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Cell Cycle / physiology*
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Cell Cycle Proteins / drug effects
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Cell Movement
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Cells, Cultured
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Cyclin A / metabolism
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Cyclin-Dependent Kinase 2
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Cyclin-Dependent Kinase Inhibitor Proteins
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Cyclin-Dependent Kinase Inhibitor p27
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Cyclin-Dependent Kinases / metabolism
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Cytoplasm / metabolism
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Cytoskeleton / metabolism
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Cytoskeleton / ultrastructure
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Fibroblasts / cytology
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Fibroblasts / metabolism
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Fungal Proteins / metabolism
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Hepatocyte Growth Factor / metabolism
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Hepatocyte Growth Factor / pharmacology
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Humans
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Liver Neoplasms / drug therapy
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Liver Neoplasms / metabolism
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Liver Neoplasms / pathology
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Molecular Sequence Data
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Phosphorylation
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Protein Serine-Threonine Kinases / metabolism
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Proto-Oncogene Mas
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Repressor Proteins*
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Saccharomyces cerevisiae Proteins*
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Tumor Suppressor Proteins / drug effects
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / metabolism*
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rac GTP-Binding Proteins / metabolism*
Substances
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Actins
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Cell Cycle Proteins
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Cyclin A
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Cyclin-Dependent Kinase Inhibitor Proteins
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FAR1 protein, S cerevisiae
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Fungal Proteins
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MAS1 protein, human
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Proto-Oncogene Mas
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Recombinant Proteins
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Repressor Proteins
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Saccharomyces cerevisiae Proteins
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Tumor Suppressor Proteins
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Cyclin-Dependent Kinase Inhibitor p27
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Hepatocyte Growth Factor
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Protein Serine-Threonine Kinases
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CDC2-CDC28 Kinases
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CDK2 protein, human
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Cyclin-Dependent Kinase 2
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Cyclin-Dependent Kinases
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rac GTP-Binding Proteins