Induction of cellular senescence by transfection of cytosolic mortalin cDNA in NIH 3T3 cells.
We have recently identified a novel member of hsp70 family (mortalin) as a mortality marker (Wadhwa, R., Kaul, S. C., Ikawa, Y., and Sugimoto, Y. (1993) J. Biol. Chem. 268, 6615-6621). It has distinct intracellular distribution in mortal and immortal fibroblasts. Here, we report that the cytosolic (mot-1) and the perinuclear (mot-2) forms of mortalin cDNA cloned from mortal and immortal cells, respectively, differ by only two bases in the open reading frame, resulting in two amino acid changes. The induced expression of the cytosolic form by transfection of mot-1 cDNA (isolate from CD1-ICR mouse embryonic fibroblasts) to NIH 3T3 cells induced cellular senescence. However, the perinuclear form expressed by mot-2 cDNA (isolate from NIH 3T3 cells) did not yield an equivalent effect. The data suggest the senescence-inductive function of cytosolic mortalin and implicitly point to a genetic event involved in immortalization.
Wadhwa
R
R
National Institute of Bioscience and Human Technology, Agency of Industrial Science and Technology, Ibaraki, Japan.
Kaul
S C
SC
Sugimoto
Y
Y
Mitsui
Y
Y
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002352:Carrier Proteins; D016922:Cellular Senescence / Q000502:physiology*; D003001:Cloning, Molecular; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D017433:Protein Structure, Secondary; D012313:RNA / Q000096:biosynthesis; D015183:Restriction Mapping; D014162:Transfection
D002352:Carrier Proteins; D018076:DNA, Complementary; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C083794:Hspa9 protein, mouse; D015345:Oligonucleotide Probes; C080352:mortalin; D012313:RNA