HELIX-LOOP-HELIX TRANSCRIPTION FACTORS REGULATE ID2 GENE PROMOTER ACTIVITY

Id-like helix-loop-helix (HLH) transcription factors are involved in t he regulation of proliferation and differentiation of several cell typ es. We isolated 5' regulatory region of mouse Id2 gene and demonstrate d that it contains several E-box clusters. These E-boxes mediate stimu latory effects of basic-HLH (bHLH) transcription factors ME1, ME2, and NSCL1 on Id2 promoter activity, Co-expression of Id2 blocks the stimu latory effect of bHLH transcription factors which suggests the presenc e of feedback loops in Id2 transcriptional regulation, Overexpression of NSCL1 in F9 cells blocks the downregulation of Id2 gene expression during retinoic acid induced differentiation. Our data demonstrate tha t bHLH transcription factors regulate Id2 gene expression.