Dietary restriction and triiodothyronine (T3) regulation of malate-aspartate shuttle enzymes in the liver and kidney of mice.
The activities of malate-aspartate shuttle enzymes viz., cytosolic and mitochondrial aspartate aminotransferase (c- and m-AsAT) and malate dehydrogenase (c- and m-MDH) were measured in liver and kidney of ad libitum (AL) and dietary-restricted (DR) mice and also on triiodothyronine (T3) treatment. The results show that the activity (U/mg protein) of c-AsAT is increased significantly in liver and the activities of c-MDH and m-AsAT are increased significantly in kidney during DR. On T3 treatment, the activities of both the isoenzymes (c- and m-) of MDH and AsAT are increased significantly in the liver of AL- and DR-fed mice. In the kidney, m-MDH showed no effect by T3 treatment, however, c-MDH increased significantly in both AL- and DR-fed mice. In contrast, m-AsAT is increased significantly in the kidney in AL-fed mice, but was not affected in DR-fed animals. In vitro reconstitution of malate-aspartate shuttle showed a higher activity in the liver and kidney of DR-fed mice, as compared to AL-fed ones and also in the T3-treated mice, compared to untreated ones. These findings suggest that malate-aspartate shuttle enzymes are differentially regulated during DR in mice, in order to adapt to the metabolic need of liver and kidney. T3 potentially regulates the shuttle enzymes, albeit to a varying degree in the liver and kidney of AL- and DR-fed mice.
Goyary
Danswrang
D
Department of Biochemistry, North Eastern Hill University, Shillong, India.
Sharma
R
R
D000818:Animals; D001219:Aspartate Aminotransferases / Q000378:metabolism*; D001224:Aspartic Acid / Q000378:metabolism; D031204:Caloric Restriction; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004032:Diet; D007527:Isoenzymes / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000201:enzymology; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008291:Malate Dehydrogenase / Q000378:metabolism*; D008293:Malates / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology; D014284:Triiodothyronine / Q000494:pharmacology*
D007527:Isoenzymes; D008293:Malates; D014284:Triiodothyronine; D001224:Aspartic Acid; C030298:malic acid; D008291:Malate Dehydrogenase; D001219:Aspartate Aminotransferases