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Effect of cAMP on the stability of tyrosine aminotransferase mRNA

Conference · · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
OSTI ID:6359344
cAMP, in addition to increasing the synthesis of tyrosine aminotransferase (TAT) at the level of transcription, has also been reported to cause a paradoxical effect reflected by a faster rate of decline in the rate of TAT synthesis after induction is over. One possible explanation is that cAMP affects some post-transcriptional point in TAT synthesis. The authors tested this possibility first by examining the stability of mRNA/sup TAT/. Total RNA was isolated from H35 cells incubated +/-2mM 8Br-cAMP for 3 hr and with the transcriptional inhibitor DRB and subjected to Northern Blot analysis. A TSP-cDNA probe (pCTAT-3) specific for mRNA/sup TAT/ hybridized to a single RNA species with a MW of 2.9 +/- 0.1 Kb. The amount of this species increased following exposure to either 8Br-cAMP (2-10x) or dex (5-10x), consistent with properties expected for mRNA/sup TAT/. The amount of mRNA/sup TAT/ was quantitated by densitometric scanning of autoradiograms. mRNA/sup TAT/ exhibited first-order decay kinetics under all conditions tested. In two separate experiments, the half-life of mRNA/sup TAT/ was found to be 1.8 +/- 0.5 hr in control cells, 1.9 +/- 0.3 hr in cells exposed to 8Br-cAMP and 1.5 hr in cells treated with dex, suggesting that cAMP has no effect on the stability of mRNA/sup TAT/. Thus, some other aspect of the translation process would appear to be affected. This possibility is currently being tested by in vitro translation assays.
Research Organization:
Univ. of Tennessee, Knoxville
OSTI ID:
6359344
Report Number(s):
CONF-870644-
Conference Information:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 46:6
Country of Publication:
United States
Language:
English