Nuclear accumulation of globular actin as a cellular senescence marker.
We evaluated the nuclear actin accumulation as a new marker of cellular senescence, using human diploid fibroblast (HDF), chondrocyte primary cultures, Mv1Lu epithelial cells, and Huh7 cancer cells. Nuclear accumulation of globular actin (G-actin) and dephosphorylated cofilin was highly significant in the senescent HDF cells, accompanied with inhibition of LIM kinase (LIMK) -1 activity. When nuclear export of the actin was induced by 12-O-tetradecanoylphorbol-13-acetate, DNA synthesis of the senescent cells increased significantly, accompanied with changes of morphologic and biochemical profiles, such as increased RB protein phosphorylation and decreased expressions of p21(WAF1), cytoplasmic p-extracellular signal-regulated kinase 1/2, and caveolins 1 and 2. Significance of these findings was strengthened additionally by the fact that nuclear actin export of young HDF cells was inhibited by the treatment with leptomycin B and mutant cofilin transfection, whose LIMK-1 phosphorylation site was lost, and the old cell phenotypes were duplicated with nuclear actin accumulation, suggesting that nuclear actin accumulation was accompanied with G1 arrest during cellular senescence. The aforementioned changes were observed not only in the replicative senescence but also in the senescence induced by treatment of HDF cells, Mv1Lu, primary culture of human chondrocytes, or Huh7 cells with H-ras virus infection, hydroxyurea, deferoxamine, or H(2)O(2). Nuclear actin accumulation was much more sensitive and an earlier event than the well-known, senescence-associated beta-galactosidase activity.
Kwak
In Hae
IH
Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, Korea.
Kim
Hong Seok
HS
Choi
Ok Ran
OR
Ryu
Min Sook
MS
Lim
In Kyoung
IK
D051339:Actin Depolymerizing Factors; D000199:Actins / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology*; D003676:Deferoxamine / Q000494:pharmacology; D004171:Diploidy; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006918:Hydroxyurea / Q000494:pharmacology; D007150:Immunohistochemistry; D008840:Microfilament Proteins / Q000378:metabolism
D051339:Actin Depolymerizing Factors; D000199:Actins; D008840:Microfilament Proteins; D006861:Hydrogen Peroxide; D003676:Deferoxamine; D006918:Hydroxyurea