The XXXX suppressor gene represses transcription of the @entity1 telomerase reverse transcriptase gene.

@entity1 @entity5 @entity517 @entity8587 @entity3969 @entity2215
Regulation of the @entity1 telomerase reverse transcriptase ( @entity2215 ) gene is the primary determinant for telomerase enzyme activity, which is found in @entity5 cells but is largely absent from normal somatic cells. Recent studies have shown that @entity517 protein can transcriptionally activate the @entity2215 gene. However, little is known about the repression mechanism of the @entity2215 gene and telomerase enzyme. Here, we developed an expression cloning strategy to identify cDNAs whose products can repress @entity2215 promoter activity in telomerase-positive immortal cells. Using this screen, we isolated the @entity3969 1 suppressor gene ( @entity8587 ). @entity8587 can repress @entity2215 promoter activity in 293 kidney cells. The @entity8587 binding site on the @entity2215 promoter was identified by deletional analysis. Alteration of the @entity8587 binding site markedly derepresses transcription from an isolated @entity2215 promoter by inhibiting interaction of @entity8587 with DNA. These specific repression effects of @entity8587 were not observed in HeLa cells, which express no endogenous @entity8587 . Furthermore, we show that @entity8587 can repress the endogenous @entity2215 promoter and telomerase enzyme activities. These results suggest that @entity8587 may be a transcriptional repressor of the @entity2215 gene, at least in some specific cells.
