[Study on the specific binding site of NF-k B-like factor at the 5' upstream region of human lymphotoxin gene].
Lymphotoxin(LT) is a glycoprotein secreted by activated T lymphocytes. The expression of LT gene is primarily controlled at the level of transcription. By using human LT DNA as a probe, we have carried out a RNA dot blotting test and found that the longer the Jurkat cells exposed to the PMA and PHA, the more was the endogenous LT mRNA. Results of gel retardation assay showed that nuclear extract from Jurkat cells treated with PMA and PHA formed different complexes. Changes in the complex patterns were observed in different time of PMA and PHA induction. A specific protein-binding site was mapped to a 22bp sequence at the 5' upstream region of human LT gene by DNase I footprinting analysis. This region is similar to the sequence recognized by the proteins of NF-KB family. The results of fragment competition test and homology analysis indicated that the 22-bp sequence contains a KB-like motif only, which located at base pairs -100 to -90(5' -GGGGGCTTCCC-3'). Thus the NF-KB-like factors were involved in the protein-DNA interaction. Furthermore, there were more than one retarded bands appearing in the gel retardation assay. It suggested that there may be various kinds of NF-KB-like factors involved in the regulation of LT gene transcription at the same site.
Xu
R
R
Institute of Genetics, Fudan University Shanghai.
Zhao
S
S
D001483:Base Sequence; D005796:Genes; D016322:HIV Enhancer / Q000235:genetics*; D006801:Humans; D008233:Lymphotoxin-alpha / Q000235:genetics*; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000235:genetics*; D014158:Transcription, Genetic
D008233:Lymphotoxin-alpha; D016328:NF-kappa B