Diapause Hormone-enhanced Expression of the trehalase-2 Gene Encoding a Novel Membrane-penetrating Type in Bombyx Developing Ovaries and the Gene Structure

Abstract

Through that diapause hormone enhances activity of membrane-bound trehalase in developing ovaries, Bombyx oocyte is shown to actively incorporate the blood trehalose and accumulate higher level of glycogen. Because the trehalase-1 gene encoding a soluble type is activated by diapause hormone in ovaries, it is believed that the soluble trehalase becomes to be localized on oolemma via the post-translation modification. Recently, we isolated the trehalase-2 gene encoding a novel membrane-penetrating type. Therefore, in this study it was examined whether this gene was activated by diapause hormone. The trehalase-2 gene was shown to be also activated in developing ovaries by the hormone, although the enhancement was at a lower rate than observed for the trehalase-1 gene. The structure of the trehalase-2 gene was determined and compared with those of trehalase-1 and mammalian trehalase. Several common nucleotide sequences were found in the 5’-upstream regions of the trehalase-1 and -2 genes. Thirteen intron sites of the trehalase-2 gene were much more similar to mouse or human trehalase rather than trehalase-1 that contains only one intron. In B. mori, the ancestral gene similar to trehalase-2 and mammalian trehalase is believed to have duplicated and then diverged into trehalase-1 and trehalase-2.