TSG-6 and calcium ions are essential for the coupling of inter-alpha-trypsin inhibitor to hyaluronan in human synovial fluid

AbstractObjective: To investigate the role of tumor necrosis factor stimulated gene 6 (TSG-6) and metal ions in the coupling of inter-α-trypsin inhibitor (ITI) to hyaluronan in human synovial fluid.Design: The concentration of ITI heavy chains bound to hyaluronan was determined by a two-step electrophoretic technique. Synovial fluid, TSG-6 depleted synovial fluid and metal chelated synovial fluid were tested for their ability to support the coupling of ITI heavy chains to hyaluronan.Results: When synovial fluid was mixed with an ITI-source (serum or purified ITI), coupling of ITI heavy chains to hyaluronan took place. TSG-6 immunodepleated synovial fluid lost the coupling activity, but addition of recombinant TSG-6 restored the activity. EDTA inhibited the coupling activity, but combinations of the metal-ion chelators Mg-EGTA and Ca-EGTA demonstrated, that Ca++is essential for the coupling of ITI heavy chains to hyaluronan.Conclusions: Tumor necrosis factor stimulated gene 6 (TSG-6) and calcium ions are both essential for the coupling of inter-α-trypsin inhibitor to hyaluronan in human synovial fluid

The genes for the inter-α-inhibitor family share a homologous organization in human and mouse

Inter-α-inhibitor ( IαI ) and related molecules in human are comprised of three evolutionarily related, heavy (H) chains and one light (L) chain, also termed bikunin. The latter originates from a precursor molecule that is cleaved to yield the bikunin and another protein designated α-1-microglobulin (A1m). The four H and L chains are encoded by four distinct genes designated H1, H2, H3 , and L . The L and H2 genes are localized onto human chromosomes (chr) 9 and 10, respectively, whereas the H1 and H3 genes are tandemly arranged on chr 3.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46989/1/335_2004_Article_BF00355432.pd