title: Hyaluronan synthesis and degradation in cartilage and bone.
abstract: Hyaluronan (HA) is a large but simple glycosaminoglycan composed of repeating D-glucuronic acid, beta1-3 linked to N-acetyl-D-glucosamine beta1-4, found in body fluids and tissues, in both intra- and extracellular compartments. Despite its structural simplicity, HA has diverse functions in skeletal biology. In development, HA-rich matrices facilitate migration and condensation of mesenchymal cells, and HA participates in joint cavity formation and longitudinal bone growth. In adult cartilage, HA binding to aggrecan immobilises aggrecan, retaining it at the high concentrations required for compressive resilience. HA also appears to regulate bone remodelling by controlling osteoclast, osteoblast and osteocyte behaviour. The functions of HA depend on its intrinsic properties, which in turn rely on the degree of polymerisation by HA synthases, depolymerisation by hyaluronidases, and interactions with HA-binding proteins. HA synthesis and degradation are closely regulated in skeletal tissues and aberrant synthetic or degradative activity causes disease. The role and regulation of HA synthesis and degradation in cartilage, bone and skeletal development is discussed.
authors.affiliation: Arthritis Research Group, University of Melbourne Department of Paediatrics and Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, 3052, Victoria, Australia.
authors.forename: E R
authors.initials: ER
authors.lastname: Bastow
authors.forename: S
authors.initials: S
authors.lastname: Byers
authors.forename: S B
authors.initials: SB
authors.lastname: Golub
authors.forename: C E
authors.initials: CE
authors.lastname: Clarkin
authors.forename: A A
authors.initials: AA
authors.lastname: Pitsillides
authors.forename: A J
authors.initials: AJ
authors.lastname: Fosang
mesh_terms: D000818:Animals; D001846:Bone Development / Q000502:physiology*; D001842:Bone and Bones / Q000166:cytology / Q000378:metabolism*; D002356:Cartilage / Q000378:metabolism*; D005109:Extracellular Matrix / Q000737:chemistry; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000378:metabolism*; D009024:Morphogenesis; D013583:Synovial Membrane / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; D000076002:Hyaluronan Synthases