MOLECULAR-CLONING OF THE CDNA OF MOUSE MITOCHONDRIAL NADP-DEPENDENT ISOCITRATE DEHYDROGENASE AND THE EXPRESSION OF THE GENE DURING LYMPHOCYTE-ACTIVATION

The current report documents the molecular cloning of the mouse mitoch ondrial NADP-dependent isocitrate dehydronegase (mNADP-IDH) cDNA. The cDNA was 1,863 bp in length and contained one open reading frame encod ing a 523-residue polypeptide with a predicted molecular weight of 58 kDa. The cDNA and the deduced amino acid (AG) sequence of the mouse mN ADP-IDH had a high degree of homology with those of porcine, bovine, a lfalfa, and yeast. The recombinant mNADP-IDH expressed in Escherichia coli had active enzymatic function, as well as an expected molecular w eight. The heart had the highest constitutive expression of the steady -state mNADP-IDH mRNA, followed by the kidney, while the expression of the gene in other tissues was low. The enzymatic activity of differen t tissues was in agreement with their mNADP-IDH mRNA levels. The resti ng lymphocytes had low constitutive expression of the gene, but the st eady-state mRNA could be induced 48 h after mitogen stimulation. At th e protein level, the resting lymphocytes had low enzymatic activity of mNADP-IDH, but the activity was augmented fivefold after mitogen stim ulation. The cytosolic NADP-IDH, on the contrary, remained low or unde tectable before and after the mitogen stimulation. Based on our curren t findings as well as the known roles of the mNADP-IDH in anabolism an d in the isocitrate shuttle, it is conceivable that the mNADP-IDH is n ecessary for optimizing proliferation in lymphocytes. (C) 1996 Wiley-L iss, Inc.