Identification of human autoantibodies to the transcriptional repressor ZF5.

ZF5 was originally cloned as a transcriptional repressor on the mouse c-myc promoter. It contains the Kruppel-type zinc fingers and a conserved POZ domain, which is found in a growing number of zinc finger proteins and mediate protein-protein interactions. Autoantibodies against transcription factors are sometimes found in sera from patients with high levels of anti-nuclear antibody (ANA).

ZF5, which is a Kruppel-type transcriptional repressor, requires the zinc finger domain for self-association.

ZF5, which we have cloned as a transcriptional repressor on the mouse c-myc promoter, has the POZ domain at the amino-terminus and the Kruppel-type zinc finger domain at the carboxy-terminus. In this report, we showed that ZF5 has two contradictory functions in transcription: activation of human immunodeficiency virus (HIV) promoter and repression of the HSV thymidine kinase (TK) promoter. The POZ domain contributed to the repressor activity, whereas the active function resulted from the DNA-binding ability of the zinc finger domain.

Analysis of the consensus binding sequence and the DNA-binding domain of ZF5.

Murine ZF5 is a transcription factor with five zinc finger motifs that represses the c-myc gene by binding to two GC-rich elements at the promoter region. Because of its ubiquitous expression in a variety of tissues, elucidation of biological functions and cellular target genes of ZF5 is of great interest. As the first step of identifying cellular target genes, we have attempted to determine the consensus binding motif for ZF5.

Genomic cloning and characterization of the mouse POZ/zinc-finger protein ZF5.

We isolated genomic DNA containing the entire sequence of ZF5, which was originally identified by its ability to repress the mouse c-myc promoter and which was characterized as one of the POZ (Poxvirus and zinc finger) proteins. The POZ motif is a protein-protein interaction interface found at the N-terminal region of zinc finger proteins. Sequence analysis demonstrated that the ATG translation initiation codon was separately located from the remainder of the coding sequence.

Detection of mouse skeletal muscle-specific product, which includes ZF5 zinc fingers and a VP16 acidic domain, by reverse transcriptase PCR.

ZF5, which we have cloned as a repressor on the mouse c-myc promoter, is a zinc finger protein containing Kruppel-type zinc finger and ZiN/POZ domains. In a reverse transcriptase PCR assay using mouse skeletal muscle RNA, we identified a 827 bp PCR product including the zinc finger domain of ZF5 and the acidic domain of VP16. The presence of the VP16 acidic domain induced the reduction of DNA-binding activity of the zinc finger domain.