背景
Hyaluronan or hyaluronic acid (HA) is a high molecular weight unbranched polysaccharide
synthesized by a wide variety of organisms from bacteria to mammals, and is a constituent
of the extracellular matrix. It consists of alternating glucuronic acid and N-acetylglucosamine
residues that are linked by beta-1-3 and beta-1-4 glycosidic bonds. HA is synthesized by
membrane-bound synthase at the inner surface of the plasma membrane, and the chains
are extruded through pore-like structures into the extracellular space. It serves a variety of
functions, including space filling, lubrication of joints, and provision of a matrix through
which cells can migrate. HA is actively produced during wound healing and tissue repair to
provide a framework for ingrowth of blood vessels and fibroblasts. Changes in the serum
concentration of HA are associated with inflammatory and degenerative arthropathies such
as rheumatoid arthritis. In addition, the interaction of HA with the leukocyte receptor CD44 is
important in tissue-specific homing by leukocytes, and overexpression of HA receptors has
been correlated with tumor metastasis. HAS2 is a member of the newly identified vertebrate
gene family encoding putative hyaluronan synthases, and its amino acid sequence shows
significant homology to glycosaminoglycan synthetase (DG42) from Xenopus laevis, and
human and murine hyaluronan synthase 1.
