Neuropeptides, Peptide Hormones, and Their Receptors of a Tunicate, Ciona intestinalis
The critical phylogenetic position of the ascidian, Ciona intestinalis, as the closest relative of vertebrates, suggested its potential applicability as a model organism in a wide variety of biological events including the nervous, neuroendocrine, and endocrine regulation. To date, approximately 40 neuropeptides and/or peptide hormones and several cognate receptors have been identified. These peptides are categorized into two types: (1) orthologs of vertebrate peptides, such as cholecystokinin, GnRH, tachykinin, vasopressin, and calcitonin, and (2) novel family peptides such as LF peptides and YFL/V peptides. Ciona GnRH receptors (Ci-GnRHR) were found to be multiplicated in the Ciona-specific lineages and to form unique heterodimers between Ci-GnRHR1 and R4 and between Ci-GnRHR2 and R4, leading to fine-tuning of the generation of second messengers. Furthermore, Ciona tachykinin was shown to regulate a novel protease-associated follicle growth pathway. These findings will pave the way for the exploration of both conserved and diversified endocrine, neuroendocrine, and nervous systems in the evolutionary lineage of invertebrate deuterostomes and/or chordates. In this chapter, we provide an overview of primary sequences, functions, and evolutionary aspects of neuropeptides, peptide hormones, and their receptors in C. intestinalis.
CT gene-related peptide
CT receptor-stimulating peptide
All ascidians were provided by Kyoto University through the National Bio-Resource Project of the MEXT, Japan. This study was funded by the Japan Society for the Promotion of Sciences, grant 16K07430 to H.S.
- Aoyama M, Kawada T, Fujie M, Hotta K, Sakai T, Sekiguchi T, Oka K, Satoh N, Satake H (2008) A novel biological role of tachykinins as an up-regulator of oocyte growth: identification of an evolutionary origin of tachykininergic functions in the ovary of the ascidian, Ciona intestinalis. Endocrinology 149:4346–4356CrossRefGoogle Scholar
- Katafuchi T, Kikumoto K, Hamano K, Kangawa K, Matsuo H, Minamino N (2003) Calcitonin receptor-stimulating peptide, a new member of the calcitonin gene-related peptide family. Its isolation from porcine brain, structure, tissue distribution, and biological activity. J Biol Chem 278:12046–12054CrossRefGoogle Scholar
- Kawada T, Sekiguchi T, Sugase K, Satake H (2009b) Evolutionary aspects of molecular forms and biological functions of oxytocin family peptides. In: Jastrow H, Feuerbach D (eds) Handbook of oxytocin research: synthesis, storage and release, actions and drug forms. Nova Science, Hauppage, NY, pp 59–85Google Scholar
- Kawada T, Aoyama M, Sakai T, Satake H (2013) Structure, function, and evolutionary aspects of invertebrate GnRHs and their receptors. In: Scott-Sills E (ed) Gonadotropin-releasing hormone (GnRH): production, structure and functions. Nova Science, New York, pp 1–16Google Scholar
- Matsubara S, Kawada T, Sakai T, Aoyama M, Osugi T, Shiraishi A, Satake H (2016) The significance of Ciona intestinalis as a stem organism in integrative studies of functional evolution of the chordate endocrine, neuroendocrine, and nervous systems. Gen Comp Endocrinol 227:101–108CrossRefGoogle Scholar
- Satake H, Kawada T (2006a) Neuropeptides, hormones, and their receptors in ascidians: emerging model animals. In: Satake H (ed) Invertebrate neuropeptides and hormones: basic knowledge and recent advances. Transworld Research Network, Trivandrum, pp 253–276Google Scholar
- Sekiguchi T, Kuwasako K, Ogasawara M, Takahashi H, Matsubara S, Osugi T, Muramatsu I, Sasayama Y, Suzuki N, Satake H (2016) Evidence for conservation of the calcitonin superfamily and activity-regulating mechanisms in the basal chordate Branchiostoma floridae: insights into the molecular and functional evolution in chordates. J Biol Chem 291:2345–2356CrossRefGoogle Scholar
- Sekiguchi T, Shiraishi A, Satake H, Kuwasako K, Takahashi H, Sato M, Urata M, Wada S, Endo M, Ikari T, Hattori A, Srivastav AK, Suzuki N (2017) Calcitonin-typical suppression of osteoclastic activity by amphioxus calcitonin superfamily peptides and insights into the evolutionary conservation and diversity of their structures. Gen Comp Endocrinol 246:294–300CrossRefGoogle Scholar