| Research Abstract |
Na, K-ATPase alpha and beta subunit isoform genes were studied for their molecular apparatus of expression regulation : 5' upstream cis-elements and the corresponding trans-acting factors. Isoform genes used were house-keeping alpha1 subunit gene, alpha2 subunit gene expressed mainly in muscle cells, and beta2 subunit gene whose product is also known as AMOG (adhesion molecule on glig).
alpha1 : A regulatig region (ARE=alpha1 gene regulation element) was found at -102--61. At least six kinds of protein binding factors interact at the ARE region. Several factors are already known to regulate the expression of other genes (HEB and ATF). A new factor, AREB6, was obtained by south-western cloning. AREB6 is a Zn-finger protein. The seven fingers are separated into two clusters of three and four, and located in the N-and C-halves of the molecule, respectively. Up-or down-regulating effects of these elements were different according to different cells transfected, indicating complex accomodation of Na, K-ATPase expression regulation.
alpha2 : Two Sp1-binding and a similar(GGGAGG)sequences and two E-boxes are found at -175--108. Several fold expression activation by this region was observed in the transfection to the myoblast-derived L6 cells.
beta2 : The specific element, AMRE (AMOG regulating element), which is an expression regulating region in rat neuroblastoma-derived 103B cells, was also shown to regulate Na, K-ATPase gene expression in cultured rat astro-cyte cells as well as other cells from several other tissues. A trans-acting factor to AMRE was found to be competed by an Sp1-binding sequence. The binding was also inhibited by anti-Sp1 antibody.
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