Dexamethasone enhances expression of mitochondrial oxidative
-phosphorylation genes in rat distal colon.
Rachamim, Nurit, Hedva Latter, Nikolai Malinin, Carol Asher, Hanna
Wald, and Haim Garty.
Dept. of Membrane Research & Biophysics, The Weizmann Institute
of Science, Rehovot 76100, Israel
APStracts 2:0233C, 1995.
Dexamethasone and aldosterone are major activators of Na+ reabsorption
in tight epithelia. The genes whose expression mediates the steroid
actions are mostly unknown. To identify such genes, we performed
differential screening of a rat colon cDNA library with total 32P
-cDNA probes reverse transcribed from steroid-stimulated and steroid
-depleted poly A+ RNA. Several cDNAs whose corresponding mRNA is
enhanced 2-3 fold following dexamethasone injection, were identified.
Partial sequencing indicated that four of them code for subunits of
cytochrome c oxidase and 16S mithocondrial rRNA. The dexamethasone
-induced increase in mitochondrial RNA abundance could not be mimicked
by a low salt diet, found to increase plasma aldosterone from 1.0 0.1
to 12.8 1.4 nM. Induction of mitochondrial genes by adrenal steroids
may serve to prevent limitation of transport by the ATP supply to the
Na+/K+ pump under conditions of maximal stimulation of Na+ transport.
Received 9 January 1995; accepted in final form 31 May 1995.
APS Manuscript Number C16-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.