Brittlestars Galactosaminoglycans and Tools to Study their Structure

Abstract: In all living organisms, biological activities such as proper functioning and co-ordination of different organs will depend on different cells and molecular interactions. In some organisms the loss of functional organs or damage of organs can be lethal, whereas in others a special process called regeneration can retrieve lost organs. The molecular details of regeneration are still not completely understood in many organisms. Echinoderms are close to vertebrates in the evolutionary tree and are well known for their amazing regeneration capacity. So we chose to investigate the molecular processes of regeneration mechanism with an interest towards our favorite groups of molecules, glycosaminoglycans (GAGs). GAGs are linear polysaccharides, expressed on all cell surfaces and extracellular space and are also known to be involved in many cellular activities. We aimed to characterize the GAGs present in Echinodermata species Amphiura filiformis and investigated their role during arm regeneration.In Paper I we characterized the structure and function of GAGs from A. filiformis and identified that A. filiformis contains CS/DS type of GAGs, but no HS. The sulfation degree of these CS/DS is close to the one of heparin, i.e. they are highly sulfated. These chains are able to bind FGF-2 growth factor and induce FGF-2 mediated cell signaling. In Paper II we further characterized these GAGs for their localization and for their role in arm regeneration in A. filiformis. Immuno- and histochemical stainings on arm sections revealed that CS/DS GAGs are localized around the podia, surrounding the water vascular system, and around the muscle tissues. Inhibition of sulfated GAG biosynthesis by chlorate treatment affected the regeneration efficiency of the arms, which may be an indication of the importance of CS/DS structures in A. filiformis arm regeneration. We also characterized some bacterial sulfatases in Paper III and a lyase in Paper IV from human and canine gut symbiotic bacteria. Here we sought to find the substrate specificity and optimal conditions for these enzymes’ activities. Our findings suggest that these polysaccharide lyase and sulfatases can be used as potential tools to characterize different GAG structures and their application could further add knowledge on diseases mechanisms related to host pathogen interactions.