[23 Redox Control of 20S Proteasome

By Bertrand Friguet, Anne-Laure Bulteau, Mariangela Conconi, and ISABELLE PETROPOULOS

Introduction

Oxidative modifications of proteins have been implicated in age- and disease-related impairment of cellular functions and are known to affect protein turnover.1 ~3 Because the 20S proteasome has been shown to be the major actor in the degradation of oxidized protein4 and consequently to be important in the regulation of the steady state level of altered proteins in the cell, the fate of proteasome subjected to oxidative processes has deserved specific attention.5"9 On oxidative stress, an increase in intracellular proteolysis of oxidized protein is well documented in different cell systems although no upregulation of proteasome subunits synthesis has

1 B. S. Berlett and E. R. Stadtman, J. Biol. Chem. 272, 20313 (1997).

2 T. Grune, T. Reinheckel, and K. J. Davies, FASEB J. 11, 526 (1997).

3 B. Friguet, A. L. Bulteau, N. Chondrogianni, M. Conconi, and I. Petropoulos, Ann. N.Y. Acad. Sci. 908,143 (2000).

4 T. Grune, T. Reinheckel, M. Joshi, and K. J. Davies, J. Biol. Chem. 270, 2344 (1995).

5 M. Conconi, L. I. Szweda, R. L. Levine, E. R. Stadtman, and B. Friguet, Arch. Biochem. Biophys. 331,232 (1996).

6 P. R. Strack, L. Waxman, and J. M. Fagan, Biochemistry 35, 7142 (1996).

7 M. Conconi and B. Friguet, Mol. Biol. Rep. 24,45 (1997).

8 M. Conconi, I. Petropoulos, I. Emod, E. Turlin, F. Biville, and B. Friguet, Biochem. J. 333, 407 (1998).

9 T. Reinheckel, N. Sitte, O. Ullrich, U. Kuckelkorn, K. J. Davies, and T. Grune, Biochem. J. 335,637 (1998).

redox sensor.7 Figure 7 shows P0 graphs of two separate channels before and after labeling with CPM. Both channels respond strongly to symmetric -180 mV transmembrane redox potential and are negatively regulated by a —220/—180 mV cisltrans gradient [compare Fig. 7, bars 1-3 (left) and P0 graphs (right)]. After exposing the channels to 20 nM CPM for 2 min [Fig. 7, bar 4 (marked with an asterisk), CPM removed from the bath by extensive perfusion of the chamber with 25 volumes of buffer], neither channel responds to a -180/-180 mV symmetric cisltrans redox gradient (compare bars 4 and 5 in Fig. 7).

Acknowledgments

This work was supported by NIH Grants 2R01AR43140 and 1POAR17605.

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