Insight into the molecular and functional diversity of cnidarian neuropeptides.

Toshio Takahashi,Noriyo Takeda

doi:10.3390/ijms16022610

Abstract

Cnidarians are the most primitive animals to possess a nervous system. This phylum is composed of the classes Scyphozoa (jellyfish), Cubozoa (box jellyfish), and Hydrozoa (e.g., Hydra, Hydractinia), which make up the subphylum Medusozoa, as well as the class Anthozoa (sea anemones and corals). Neuropeptides have an early evolutionary origin and are already abundant in cnidarians. For example, from the cnidarian Hydra, a key model system for studying the peptides involved in developmental and physiological processes, we identified a wide variety of novel neuropeptides from Hydra magnipapillata (the Hydra Peptide Project). Most of these peptides act directly on muscle cells and induce contraction and relaxation. Some peptides are involved in cell differentiation and morphogenesis. In this review, we describe FMRFamide-like peptides (FLPs), GLWamide-family peptides, and the neuropeptide Hym-355; FPQSFLPRGamide. Several hundred FLPs have been isolated from invertebrate animals such as cnidarians. GLWamide-family peptides function as signaling molecules in muscle contraction, metamorphosis, and settlement in cnidarians. Hym-355; FPQSFLPRGamide enhances neuronal differentiation in Hydra. Recently, GLWamide-family peptides and Hym-355; FPQSFLPRGamide were shown to trigger oocyte maturation and subsequent spawning in the hydrozoan jellyfish Cytaeis uchidae. These findings suggest the importance of these neuropeptides in both developmental and physiological processes.

Highlights

Neurotransmission is the process by which signaling molecules called neurotransmitters, including peptides, are released by a neuron and bind to and activate the receptors of another neuron
We describe FMRFamide-like peptides (FLPs), GLWamide-family peptides, and Hym-355; FPQSFLPRGamide, which have diverse functions as neuropeptides in cnidarians, including two species of Hydrozoa (Hydra, Hydractinia, and jellyfish) and Anthozoa
Morishita et al [46] have purified two peptides, FPQSFLPRGamide (Hym-355) and SFLPRGamide, from H. magnipapillata using high performance liquid chromatography fractionation and immunological assays. They concluded that Hym-355; FPQSFLPRGamide and SFLPRGamide are the substances that account for the vasopressin-like immunoreactivity in the hydra nervous system

Summary

Introduction

Neurotransmission is the process by which signaling molecules called neurotransmitters, including peptides, are released by a neuron and bind to and activate the receptors of another neuron. Cnidarians have a diffuse nervous system including a nerve net in which the sensory and ganglionic neurons and their processes are interspersed among the epithelial cells of both layers. Using the model organism Hydra, which can be used to study cell biological and regenerative mechanisms and physiological processes regulated by peptide signaling molecules, we developed a novel peptidomic approach to the isolation and identification of functional peptide signaling molecules for this organism (the Hydra Peptide Project) [8]. We describe FLPs, GLWamide-family peptides, and Hym-355; FPQSFLPRGamide, which have diverse functions as neuropeptides in cnidarians, including two species of Hydrozoa (Hydra, Hydractinia, and jellyfish) and Anthozoa (coral). We discuss the importance of the neuropeptides in the development and physiology of the cnidarians

Cnidarian Neuropeptides

GLWamides

Hym-355

Functional Diversity of Cnidarian Neuropeptides

Conclusions