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リエゾンラボ研究会
発表内容

Title:
Molecular and functional characterization of neuropeptides and peptide hormones of a protochodate, Ciona intestinalis: the “from Ciona to Mammals” strategy

Honoo Satake
Bioorganic Research Institute
Suntory Foundation for Life Sciences

Abstract:
The critical phylogenetic position of the ascidian, Ciona intestinalis, as a protochordate suggested its potential appliciability as a model organism in diverse fields. However, only a few ascidian peptides were structurally and functionally characterized from ascidians. In our recent study, a combination of mass spectrometric analyses and database-searching detected 40 C. intestinalispeptides. These peptides are categorized into three types. i) orthologs of vertebrate peptides including tachykinin, calcitonin, galanin, RF-amide peptides, and neurotensin-like peptides. ii) vasopressin and GnRH-related peptide possessing ascidian-specific molecular forms and/or functions. iii) novel family peptides such as LF peptides and YFL/V peptides. These results show that ascidians possess a greater number of homologs and/or prototypes of vertebrate neuropeptides and peptide hormones than any other invertebrates, and that several ascidian peptides were diverged in ascidian-specific evolutionary lineages. We also proved the presence of species-specific functional regulation of GnRH receptors via heterodimerization with their orphan GnRH receptor pralogs. Furthermore, we have substantiated a novel protease-associated follicle growth pathway regulated by tachykinins and neurotensin-like peptides in C. intestinalis, which is the first characterization of biological roles of tachykinins and neurotensins in ovaries of any organisms. In addition, our recent studies have been veryfing that this novel tachyninergic protease-directed follicle growth is essentially conserved in mammalian follicle growth at early stages, leading to the clarification of novel molecular mechanisms underlying follicle growth in the premature ovary.

References:
1. Sakai, T., Aoyama, M., Kawada, T., Kusakabe, T., Tsuda, M., Satake, H. (2012) “Evidence for differential regulation of GnRH signaling via heterodimerization among GnRH receptor paralogs in the protochordate, Ciona intestinalis.” Endocrinology. 153(4), 1841-1849. Kawada, T.,

2. Ogasawara, M., Sekiguchi, T., Aoyama, M., Hotta, K., Oka, K, Satake, H. (2011) “Peptidomic analysis of the central nervous system of the protochordate, Ciona intestinalis: homologs and prototypes of vertebrate peptides and novel peptides.” Endocrinology. 152(6), 2416-2427.

3. Sakai, T., Aoyama, M., Kusakabe, T., Tsuda, M., Satake, H. (2010) “Functional diversity of signaling pathways through G protein-coupled receptor heterodimerization with a species-specific orphan receptor subtype.” Mol. Biol. Evol. 27(5), 1097-1106. Aoyama, M., Kawada, T.,

4. Fujie, M., Hotta, K., Sakai, T., Sekiguchi, T., Oka, K., Satoh, N., Satake, H. (2008) “A novel biological role of tachykinins as an upregulator of oocyte growth: identification of an evolutionary origin of tachykinergic functions in the ovary of the ascidian, Ciona intestinalisEndocrinology149(9), 4346-4356.

5. Satake, H., Ogasawara, M., Kawada, T., Masuda, K., Aoyama, M., Minakata, H., Chiba, T., Metoki, H., Satou, Y., Satoh, N. (2004) “Tachykinin and tachykinin receptor of an ascidian, Ciona intestinalis: Evolutionary origin of the vertebrate tachykinin family.” J. Biol. Chem. 279(51), 53798-53805.