ABSTRACT
Glycosaminoglycans (GAGs) are polysaccharides that are present on cell surfaces or in the extracellular matrix as free molecules or proteoglycans (PGs). GAGs are especially abundant in articular cartilage. Hyaluronan (hyaluronic acid; HA), chondroitin 4-and 6-sulfates, keratan sulfates (KSs) I and II, heparin, heparan sulfate, and dermatan sulfate are the most physiologically significant GAGs known. GAGs are involved in many biological functions such as embryonic development (e.g., synovial joints), wound healing, cell signaling, growth factor regulation, protein trafficking, etc. GAGs such as heparin (anticoagulant) and HA (orthopedic, ophthalmology, and cosmetic use) are also widely used clinically, and chondroitin sulfate (CS) is commonly used as a dietary supplement. Mutations in genes involved in the biosynthesis and degradation pathways of GAGs result in a number of hereditary disorders. In addition, GAGs have been implicated in diseases such as cancer, metastasis, viral infections, and amyloid diseases such as Alzheimer’s disease.[1] The main focus of this review will be on the role of GAGs and PGs in synovial joints and articular cartilage specifically.
