title: Translocational inefficiency of intracellular proteins in senescence of human diploid fibroblasts.
abstract: In order to investigate signal transduction pathways and related changes of actin cytoskeleton organization in cellular senescence, H-ras double mutants--V12S35, V12G37, and V12C40--were constitutively expressed in human foreskin fibroblast (HDF). Senescent HDF cells as well as the H-ras mutant expressers accumulated p-Erk1/2 in the cytoplasm with increased MEK activity and failed to translocate it to nuclei on EGF stimulation. Senescent HDF cells, V12S35 and V12G37 expressers, revealed a failure to export actin fiber from nucleus to cytoplasm and also to form stress fibers. Perinuclear expression of Rac1 was prominent in the HDF cells and V12C40 expresser; however, in the V12S35 expresser, translocation of Rac1 from perinucleus to nucleus and strong expression of RhoA were obvious. In summary, the H-ras double mutant expressers induced premature senescence through the MEK pathway, accompanied by nuclear accumulation of actin and Rac1 proteins, cytoplasmic retention of p-Erk1/2, and marked induction of RhoA expression, suggesting the translocational inefficiency of the intracellular proteins in the senescent HDF cells.
authors.affiliation: Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, Korea. iklim@madang.ajou.ac.kr
authors.forename: I K
authors.initials: IK
authors.lastname: Lim
authors.forename: K W
authors.initials: KW
authors.lastname: Hong
authors.forename: I H
authors.initials: IH
authors.lastname: Kwak
authors.forename: G
authors.initials: G
authors.lastname: Yoon
authors.forename: S C
authors.initials: SC
authors.lastname: Park
mesh_terms: D016475:3T3 Cells / Q000187:drug effects / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism; D021581:Active Transport, Cell Nucleus; D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D022081:Cell Surface Extensions; D016922:Cellular Senescence / Q000502:physiology*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000502:physiology; D003593:Cytoplasm / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000502:physiology* / Q000648:ultrastructure; D004171:Diploidy; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D019942:Genes, p16; D016158:Genes, p53; D011905:Genes, ras; D006801:Humans; D048728:MAP Kinase Kinase Kinase 1; D020935:MAP Kinase Signaling System; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology; D022502:Stress Fibers / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D000099149:Ezrin
chemical_list: D000199:Actins; D001798:Blood Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D003598:Cytoskeletal Proteins; D048728:MAP Kinase Kinase Kinase 1; D008565:Membrane Proteins; D008840:Microfilament Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010750:Phosphoproteins; D020033:Protein Isoforms; D017346:Protein Serine-Threonine Kinases; D016283:Proto-Oncogene Proteins p21(ras); D016159:Tumor Suppressor Protein p53; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D000099149:Ezrin; C071058:moesin; C071776:radixin; C482576:MAP3K1 protein, human; C482578:Map3k1 protein, mouse; C501009:HRAS protein, human