REPROGRAMMING OF NUCLEAR PROTEASOMES IN K562 CELLS UNDERGOING APOPTOSIS. II. EFFECT OF ANTICANCER DRUG
DOXORUBICIN
A. S. Tsimokha,* A. G. Mittenberg, I. N. Evteeva, V. A. Kulichkova,
I. V. Kojukharova, J. B. Ermolaeva, I. M. Konstantinova
Institute of Cytology RAS, St. Petersburg;
* e-mail: atsimokha@mail.cytspb.rssi.ru
The induction of apoptosis in K562 cells by doxorubicin (DR) was used as a model to investigate changes in the
subunit composition, phosphorylation state and enzymatic activities of 26S proteasomes in cells undergoing the
programmed death. Here we have shown for the first time that proteasomes isolated from the nuclei of control and
induced K562 cells differ in their subunit patterns, as well as in the phosphorylation state of subunits on threonine
and tyrosine residues. It has been shown for the first time that trypsin- and chymotrypsin-like, and the
endoribonuclease activities of nuclear 26S proteasomes are affected under influence of DR on K562 cells. Treatment
of K562 cells with DR leads to modification of zeta/α5 and iota/α6 proteasomal subunits associated with
RNase activity of proteasomes. These findings confirm our hypothesis about so-called reprogramming of nuclear
proteasomes population in undergoing apoptosis K562 cells which is manifested by changes in proteasomal composition,
phosphorylation state, and enzymatic activities during the programmed cell death.
Key words: apoptosis, doxorubicin, nuclear proteasomes, phosphorylation, proteolytic activity,
ribonucleases, threonine, tyrosine
Back
Contents
Main
|
