Transcriptional activation of the tumor necrosis factor alpha-inducible zinc finger protein, A20, is mediated by kappa B elements.

摘要: A20 was first identified as a tumor necrosis factor (TNF) primary response transcript encoding 790-amino acid protein with unique zinc finger motif. Recently, shown to protect cells from TNF-induced cytotoxicity in variety of cell lines. Nuclear run-on studies previously established that TNF activates at the transcriptional level. To further characterize mechanism by which gene, we have cloned 5'-flanking sequences and TNF-responsive elements within promoter. The transcription initiation site mapped both primer extension S1 nuclease protection experiments position 4.2 kilobases (kb) upstream initiator methionine; second exon were separated 3.9-kb intron. Sequences start 76% GC-rich contained six Sp1 binding sites TATA-like sequence -29 but lacked consensus CCAAT site. Transfection Jurkat T-cells an array promoter CAT constructs showed two kappa B residing -54 -66 required for induction TNF. Supporting this notion, DNA electrophoretic mobility shift assays using nuclear extracts unstimulated TNF-stimulated demonstrated B-specific TNF-activated end-labeled probe containing sequences. Finally, evidence obtained cotransfection negatively regulated its own expression.