SELECTIVE EFFECT OF INDUCTORS OF APOPTOSIS ON THE ENDORIBONUCLEASE ACTIVITY OF 26S
PROTEASOMES AND α-RNP PARTICLES IN K562 CELLS: POSSIBLE INVOLVEMENT OF 26S PROTEASOMES AND α-RNP
IN THE REGULATION OF RNA STABILITY
M. V. Toktarova, 1 V. A. Kulichkova, 1 A. G. Mittenberg, 1
I. V. Kozhuharova, 1 I. V. Volkova, 1 Yu. B. Ermolaeva, 1 A. V. Peshekhonov, 1
T. N. Ignatova, 2 L. N. Cause, 1 I. M. Konstantinova 1 *
1 Institute of Cytology RAS, St. Petersburg, Russia and 2 University of Florida,
Gainsvillc, Florida, USA;
* e-mail: ikonst@mail.cytspb.rssi.ru
It has been shown that endoribonuclease activity of α-RNP particles and 26S proteasomes are changed under
the action of inductors of programmed cell death. Treatment of K562 cells with inductors of apoptosis - doxorubicin (adriamycin) and
diethylmaleate - lead to a significant stimulation of RNAse activity of α-RNP and to reduction of proteasome RNase activity.
The enzymatic activity under study has been shown to be specifically and selectively dependent on phosphorylation of subunits of
α-RNP particles and 26S proteasomes. The characteristics of RNAse activity of different subpopulations of proteasomes differ.
The specificity of a subpopulation of proteasomes exported from the cell has been demonstrated. Proteasome and α-RNP
involvement in the coordinated control of stability of various specific messenger RNA molecules is suggested, and one of the
mechanisms of this control might be the export of specific subpopulation of proteasomes from the cell.
Key words: proteasomes, mRNA stability, ribonucleases, apoptosis, doxorubicin, adriamycin,
diethylmaleate
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