Thyroid hormone regulation of malic enzyme synthesis. Dual tissue-specific control

• Published in: The Journal of biological chemistry Vol. 261; no. 22; pp. 10290 - 10292
• Main Authors: Dozin, B, Magnuson, M A, Nikodem, V M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 05-08-1986; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Biological and medical sciences; Cell Nucleus - metabolism; Cell physiology; Cytoplasm - metabolism; Enzyme Induction - drug effects; Female; Fundamental and applied biological sciences. Psychology; Hormonal regulation; Liver - enzymology; Malate Dehydrogenase - biosynthesis; Malate Dehydrogenase - genetics; Molecular and cellular biology; Myocardium - enzymology; Rats; Rats, Inbred Strains; RNA, Messenger - metabolism; Transcription, Genetic; Triiodothyronine - pharmacology; Rat; Rodentia; Biosynthesis; Cytosol; Tissue; Vertebrata; Regulation(control); Specificity; Mammalia; Animal; Hormonal regulation; Malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+); Thyroid hormone
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)67522-2

The regulatory mechanism(s) involved in the tissue-specific induction of cytosolic malic enzyme (EC 1.1.1.40) by triiodothyronine (T3) have been investigated in rat liver and heart. In these two tissues, cellular malic enzyme mRNA accumulates to different extents in response to hormonal stimulation (11-16- and 3-4-fold above the respective basal levels) (Dozin, B., Magnuson, M. A., and Nikodem, V. M. (1985) Biochemistry 24, 5581-5586). To gain further insight into this pretranslational control, nuclear in vitro run-off transcription assays were performed and correlated with the levels of malic enzyme RNA sequences in cytoplasm. The data demonstrate that the rate of transcription of the malic enzyme gene is stimulated by T3 to similar extents in liver and heart (3-4-fold above the basal activity). In liver, T3 also promotes an additional increase in cellular malic enzyme mRNA. This additional effect could be due to a tissue-specific change in the rate of degradation of cytoplasmic mRNA or to an effect on malic enzyme mRNA in the nucleus.