DIFFERENCES IN DNA-BINDING EFFICIENCY OF SP1 TO ALDOLASE AND PYRUVATE-KINASE PROMOTER CORRELATE WITH ALTERED REDOX STATES IN RESTING AND PROLIFERATING RAT THYMOCYTES

Thymocytes induce their glycolytic enzymes as they undergo transition from the resting to the proliferating state. Corresponding increases i n mRNA levels point to a transcriptional regulation. Electrophoretic m obility shift assays revealed that the DNA-binding efficiency of Sp1 i s increased when nuclear extracts from proliferating compared to resti ng rat thymocytes were used, Here we demonstrate that hydrogen peroxid e, added to nuclear extract from proliferating cells, decreases the Sp 1 DNA-binding activity, whereas in nuclear extracts from resting cells dithioerythritol fully restores DNA-binding efficiency. Moreover we s how that in contrast to resting thymocytes, production of reactive per oxide anions upon priming with phorbol 12-myristate 13-acetate is near ly abolished in the proliferating cells, From these results we propose that reactive oxygen intermediates affect the interaction of the Sp1 transcription factor with its consensus sequence and subsequently regu late glycolytic gene expression.