科研之友
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摘要
In a previous study specific protein binding to the uteroglobin (UG) promoter was detected in gel retardation assays using progesterone-dominated rabbit uterine nuclear extract proteins. Those findings have now been extended to reveal the components within that specific shifted band. Southwestern blotting and photoaffinity cross-linking of protein-DNA complexes by UV irradiation demonstrate binding of two proteins with apparent molecular masses of 94 and 115 kDa to a 126-basepair UG gene fragment (UG126 -194/-68). To further investigate the tissue- and hormone-specific expression of the UG gene and to relate that specificity to promoter binding, RNA was prepared from rabbit uterus, kidney, and lung after 5 consecutive days of progesterone treatment. Northern blots of total RNA showed an absence of UG expression in kidney, while UG message was detected in uterus and lung. Protein binding to UG promoter DNA was absent in extracts from nuclei of kidney and HeLa cells, where the gene is not expressed, and from lung, where the gene is expressed but not regulated by progesterone. Digestion of the uterine protein-DNA complex using the nuclease activity of phenanthroline-copper ion and DNAase-I revealed two footprints. Protection was similar on both DNA strands, indicating no preference of protein binding to one DNA strand over the other. Taken together, the results provide strong indirect evidence that transcriptional activation of UG gene expression by progesterone requires binding of two additional proteins to UG promoter elements.
- 出版日期1991-7
