Pertussis toxin alters the concentration and turnover of manganese
superoxide dismutase in rat lung.
Berkovich, Alla, Donald Massaro, Linda Biadasz Clerch.
Lung Biology Laboratory and the Departments of Pediatrics and
Medicine, Georgetown University School of Medicine, Washington, DC
20007-2197
APStracts 3:0129L, 1996.
Treatment of rats with pertussis toxin (PTX) decreases the activity of
manganese superoxide dismutase (MnSOD) in the lung and results in
oxygen toxicity in air (J. Clin. Invest. 93: 2482-2489, 1994). To
examine aspects of the mechanism of the PTX-induced fall in MnSOD
activity we injected rats with PTX (50[mu][gamma] kg-1), killed them
72 hrs later, and measured the activity, concentration, specific
activity, and turnover of MnSOD in the lung. Treatment with PTX
caused a 50% fall in MnSOD activity and MnSOD concentration but no
change in MnSOD specific activity. PTX also caused an increase in
MnSOD mRNA concentration, a fall in MnSOD synthesis, and an increase
in half-life of MnSOD and general proteins. We conclude the PTX
-induced low concentration of MnSOD is due to a decrease of
translational efficiency. We suggest that under normoxic conditions
signal transduction via heterotrimeric guanine nucleotide binding
proteins (G proteins) regulates the expression of MnSOD at the level
of translation and MnSOD degradation.
Received 1 May 1996; accepted in final form 24 July 1996.
APS Manuscript Number L130-6.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 21 August 1996