Comparative analysis of gene expression profiles between the ovary treated with or without Ci-TK

Tachykinins (TKs) and their receptors have been shown to be expressed in the mammalian ovary. However, the biological roles for ovarian TKs have yet to be verified. Ci-TK and Ci-TK-R, characterized from the protochordate (ascidian), Ciona intestinalis, are prototypes of vertebrate TKs and their receptors. In the present study, we show a novel biological function of TKs as an inducible factor for oocyte growth using C. intestinalis as a model animal. Immunostaining demonstrated the specific expression of Ci-TK-R in test cells residing in oocytes at the vitellogenic stage. DNA microarray and real-time PCR substantiated that Ci-TK induced gene expression of several proteases including cathepsin D, chymotrypsin, and carboxypeptidase B2 and functionally unidentified lectins or glycosidases in the ovary. The enzymatic activities of the above proteases in the ovary were also shown to be enhanced by Ci-TK. Of particular significance is that treatment of Ciona oocytes with Ci-TK resulted in progression of growth from the vitellogenic stage to the post-vitellogenic stage, which was completely blocked by a TK antagonist or protease inhibitors. These results led to the conclusion that Ci-TK enhances growth of the vitellogenic oocytes via up-regulation of gene expression and enzymatic activities of the proteases. Keywords: tachykinins, ovary two samples Dye Swap design with 2 arrays