Glycosaminoglycans in Hydra magnipapillata (Hydrozoa, Cnidaria): demonstration of chondroitin in the developing nematocyst, the sting organelle, and structural characterization of glycosaminoglycans

Abstract

The hydrozoan is the simplest organism whose movements are governed by the neuromuscular system, and its de novo morphogenesis can be easily induced by the removal of body parts. These features make the hydrozoan an excellent model for studying the regeneration of tissues in vivo, especially in the nervous system. Although glycosaminoglycans (GAGs) and proteoglycans (PGs) have been implicated in the signaling functions of various growth factors and play critical roles in the development of the central nervous system, the isolation and characterization of GAGs from hydrozoans have never been reported. Here, we characterized GAGs of Hydra magnipapillata. Immunostaining using anti-GAG antibodies showed chondroitin or chondroitin sulfate (CS) in the developing nematocyst, which is a sting organelle specific to cnidarians. The CS-PGs might furnish an environment for assembling nematocyst components, and might themselves be components of nematocysts. Therefore, GAGs were isolated from Hydra and their structural features were examined. A considerable amount of CS, three orders of magnitude less heparan sulfate (HS), but no hyaluronan were found, as in Caenorhabditis elegans. Analysis of the disaccharide composition of HS revealed glucosamine 2-N-sulfation, glucosamine 6-O-sulfation, and uronate 2-O-sulfation. CS contains not only nonsulfated and 4-O-sulfated N-acetylgalactosamine (GalNAc) but also 6-O-sulfated GalNAc. The average molecular size of CS and HS was 110 and 10 kDa, respectively. It has also been established here that CS chains are synthesized on the core protein through the ubiquitous linkage region tetrasaccharide, suggesting that indispensable functions of the linkage region in the synthesis of GAGs have been conserved during evolution.

Evolutionary Differences in Glycosaminoglycan Fine Structure Detected by Quantitative Glycan Reductive Isotope Labeling

“…The actual identification of the disaccharides depends on determining the retention time relative to authentic standards, which are sometimes difficult to procure. At times the profile can be confusing due to spurious peaks or contaminants (3)(4)(5).…”

A Non-sulfated Chondroitin Stabilizes Membrane Tubulation in Cnidarian Organelles

“…GAGs are known to participate in many biological processes like signaling, cell adhesion, infection of pathogens, brain development, modulation of enzymes, cytokines, and growth factors (14,15). In a recent publication, Yamada et al (16) characterized GAGs in Hydra magnipapillata and demonstrated by immunostainings that the epitope of the anti-chondroitin antibody 473A12 is present in developing nematocysts, though the precise role of this nematocyst-specific chondroitin remained unclear. Here, we demonstrate that this chondroitin forms the outer layer of the developing nematocyst tubule, both in Hydra and the sea anemone Nematostella vectensis.…”

Identification of a Novel Chondroitin Hydrolase in Caenorhabditis elegans

“…Reports on the existence of Chn and low sulfated CS are limited. These substrates have been found in human plasma and urine (29), the dried regurgitated saliva of male Collocalia swiftlets (30), squid skin (31), the fruit fly Drosophila melanogaster (32), and the developing nematocyst of Hydra magnipapillata (33). Their physiological significance may be revealed by analyses using Chnase.…”