Definition: Hyaluronan (also called hyaluronic acid or hyaluronate) is a non-sulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues.
It is one of the chief components of the extracellular matrix, contributes significantly to cell proliferation and migration, and may also be involved in the progression of some malignant tumors.
The average 70 kg (154 lbs) person has roughly 15 grams of hyaluronan in their body, one-third of which is turned over (degraded and synthesised) every day.
Hyaluronic acid is also a component of the group A streptococcal extracellular capsule, and is believed to play a role in virulence.
Hyaluronic acid is an abundant extracellular matrix glycosaminoglycan (GAG) in skin and mesenchymal tissues, where it facilitates cell migration during wound healing, inflammation, and embryonic morphogenesis.
HA is a polysaccharide of the glycosaminoglycans (GAG) family found in the extracellular matrix (ECM) of many tissues. HA is a huge molecule that consists of many repeats of a simple disaccharide stretched end-to-end. HA binds a large amount of water, forming a viscous hydrated gel that gives connective tissue the ability to resist compression forces.
HA helps provide resilience and lubrication to many types of connective tissue, notably for the cartilage in joints. HA is also found in the matrix of migrating and proliferating cells, where it inhibits cell-to-cell adhesion and facilitates cell motility.
Ligands
CD44 a surface glycoprotein expressed by leukocytes, binds HA. Through such binding, T cells may be retained in tissues and remain bound to endothelium at sites of inflammation.
Pathology
Hyaluronan is one of the chief components of the extracellular matrix, contributes significantly to cell proliferation and migration, and may also be involved in the progression of some malignant tumors.
Hyaluronic acid is also a component of the group A streptococcal extracellular capsule, and is believed to play a role in virulence.
See also
glycosaminoglycans (GAG)
extracellular matrix (ECM)
References
Toole BP. Hyaluronan: from extracellular glue to pericellular cue. Nat Rev Cancer. 2004 Jul;4(7):528-39. PMID: 15229478