Effect of dexamethasone on mRNA levels for 5-aminolevulinate synthase in different rat tissues.
5-Aminolevulinate synthase mRNA levels from different tissues were quantitated by Northern blot hybridization analysis utilizing the rat liver 5-aminolevulinate synthase cDNA clone as probe. A 5-aminolevulinate synthase mRNA species of size 2.3 kb was seen in all the tissues examined. Densitometric scanning of the autoradiographs demonstrated that the adrenal gland contained the largest amount of 5-aminolevulinate synthase mRNA. Levels corresponding to approximately 50% of this amount were found in the small intestine, lung, heart, muscle and testes. In the liver and kidney the level was approximately 25% of that found in the adrenal gland. These results demonstrate the housekeeping role of this gene. Dexamethasone treatment for 1 day or 5 days dramatically induced 5-aminolevulinate synthase mRNA levels in the liver and small intestine, and to a lesser extent in lung, heart, kidney and muscle. Nuclear run-off experiments suggest that a post-transcriptional mechanism predominantly contributes to the dexamethasone-induced increase in 5-aminolevulinate synthase mRNA levels observed in the liver. Interestingly, in the steroidogenic tissues of the adrenal gland and testes, there was a substantial decrease in 5-aminolevulinate synthase mRNA levels after dexamethasone administration but the mechanism of this control remains to be investigated.
Srivastava
G
G
Department of Pathology, University of Hong Kong.
Kwong
S K
SK
Lam
K S
KS
May
B K
BK
D000624:5-Aminolevulinate Synthetase / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D015152:Blotting, Northern; D003907:Dexamethasone / Q000494:pharmacology*; D008297:Male; D012333:RNA, Messenger / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D014158:Transcription, Genetic
D012333:RNA, Messenger; D003907:Dexamethasone; D000624:5-Aminolevulinate Synthetase