HSP60 interacts with YB-1 and affects its polysome association and subcellular localization.
YB-1 is a DNA/RNA-binding protein which, in the cytoplasm, associates with polysomes and regulates translation. However, YB-1 has a novel nuclear localization signal, and its nuclear accumulation is correlated with cancer induction. Here we designated the amino-acid sequence as YB-NLS and demonstrated that YB-NLS is necessary for the nuclear translocation of overexpressed YB-1 in NG108-15 cells. In addition, we found that a heat shock protein, HSP60, binds to YB-NLS in the cytoplasm. Interestingly, when HSP60 expression was repressed, an increase of polysome-associated YB-1 was observed in heavy-sedimenting fractions on a sucrose gradient. Overexpression of HSP60 resulted in a decrease of YB-1 in the heavy-sedimenting fractions and suppression of YB-NLS activity. Furthermore, the NLS-deleted YB-1 was apparently associated with the heavy-sedimenting polysomes. These results suggest that HSP60 interacts with YB-1 at the YB-NLS region and acts as a regulator of polysome association and the subcellular distribution of YB-1.
Ohashi
Sachiyo
S
Research Unit of Biochemistry, College of Pharmacy, Nihon University, Narashinodai, Funabashi, Chiba 274-8555, Japan.
Atsumi
Megumi
M
Kobayashi
Shunsuke
S
D000818:Animals; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D018834:Chaperonin 60 / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D051379:Mice; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism; D011132:Polyribosomes / Q000378:metabolism*; D051381:Rats; D051840:Y-Box-Binding Protein 1 / Q000235:genetics / Q000378:metabolism*
D018834:Chaperonin 60; D019913:Nuclear Localization Signals; D051840:Y-Box-Binding Protein 1