Identification and characterization of the human inhibitor of caspase-activated DNase gene promoter.
DNA fragmentation factor is a heterodimer complex of the nuclease CAD and its specific inhibitor ICAD, which can be activated during apoptosis to induce DNA fragmentation. Although ICAD expression levels have been quantified in a variety of human cancer cells, the mechanism of ICAD gene regulation remains unknown. In this study, we identified a 106-bp TATA-less region upstream of the transcription start site as a basal promoter of the human ICAD gene. An E-Box motif, which binds transcription factors of the basic helix-loop-helix/leucine zipper family, is responsible for transcriptional activity, as demonstrated using mutated promoter-reporters. A chromatin immunoprecipitation assay further demonstrated that Myc binds to an endogenous ICAD promoter. The functional importance of Myc in the regulation of ICAD transcription was also demonstrated by knock-down of c-Myc and N-Myc gene expression, as well as their ectopic expression. Structural analysis of the human ICAD promoter and identification of factors which regulate its activity might further our understanding of the biological role of ICAD with respect to regulation of apoptosis and cancer development.
Omata
Kazuhiko
K
Department of Virology II, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, Japan.
Suzuki
Ryosuke
R
Masaki
Takahiro
T
Miyamura
Tatsuo
T
Satoh
Tazuko
T
Suzuki
Tetsuro
T
D017209:Apoptosis / Q000235:genetics* / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D003851:Deoxyribonucleases / Q000037:antagonists & inhibitors*; D015870:Gene Expression; D016259:Genes, myc; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D024363:Transcription Initiation Site; D051720:Upstream Stimulatory Factors / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D017931:DNA Primers; D004273:DNA, Neoplasm; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D051720:Upstream Stimulatory Factors; C109664:caspase-activated DNase inhibitor; D003851:Deoxyribonucleases