Proteasome is a carrier to translocate doxorubicin from cytoplasm into nucleus.
When an effective concentration of doxorubicin (DXR) was added into L1210 of a mouse leukemia cell line, DXR was rapidly distributed much more in the nuclei than in the other organelle within a few minutes. A [14C]DXR-binding fraction was obtained from the cytosol prepared from L1210 cells. The fraction was adsorbed to hydroxylapatite matrix and eluted from the matrix by 50-150 mM potassium phosphate buffer. The fraction showed high DXR-binding and Suc-Leu-Leu-Val-Tyr-MCA-degrading activity. The binding of [14C]DXR was inhibited by unlabeled DXR. Gel chromatography of the fraction with Sephacryl S-300 separated two fractions of high molecular weight (Peak I, approx. 750 kDa) and low molecular weight (Peak II). Peak I showed proteolytic activity. [14C]DXR-binding Peak I had much higher affinity to DNA-cellulose than [14C]DXR-binding Peak II. [14C]DXR-Peak I complex also was retained into the nuclei isolated from L1210 cells, temperature-dependently. These results suggest that a specific carrier to translocate DXR from cytoplasm into nucleus exists in L1210 cell and the carrier is proteasome.
Kiyomiya
K
K
Department of Toxicology, School of Veterinary Medicine, Osaka Prefecture University, Sakai, Japan.
Matsuo
S
S
Kurebe
M
M
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000378:metabolism*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004317:Doxorubicin / Q000378:metabolism*; D007939:Leukemia L1210 / Q000378:metabolism*; D051379:Mice; D009097:Multienzyme Complexes / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D014407:Tumor Cells, Cultured
D000903:Antibiotics, Antineoplastic; D002352:Carrier Proteins; D009097:Multienzyme Complexes; D004317:Doxorubicin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex