EXPRESSION OF MOUSE PHOSPHOFRUCTOKINASE-M GENE ALTERNATIVE TRANSCRIPTS - EVIDENCE FOR THE CONSERVED 2-PROMOTER SYSTEM

Molecular cloning of the 5' part of mouse phosphofructokinase M cDNA w as performed. In the 46 cDNA clones isolated, there were two classes o f 5' untranslated sequences. One had an EcoRI site within its 5' untra nslated sequence. This showed 83.0% similarity with human type B mRNA for phosphofructokinase-M. The other lacked an EcoRI site, showing 92. 9% similarity with human type C mRNA. Using the reverse-transcription PCR technique, we found that the transcript with an EcoRI site was exc lusively expressed in cardiac and skeletal muscles, while that without an EcoRI site was expressed in all the mouse tissues examined. The re sults suggested that the mouse phosphofructokinase-M gene was transcri bed through alternative splicing by the multiple promoters. This trans cription mechanism was considered to be evolutionarily conserved. The level of phosphofructokinase-M gene expression in mouse cardiac and sk eletal muscles decreased in the ketotic diabetic state. Although the r egulatory mechanism and the physiological significance are not fully k nown, this would indicate that phosphofructokinase-M gene transcripts are affected during the diabetic state.