Demonstration of the hepatocyte growth factor signaling pathway in the in vitro neuritogenic activity of chondroitin sulfate from ray fish cartilage.

BACKGROUND Chondroitin sulfate (CS) is a ubiquitous component of the cell surface and extracellular matrix and its sugar backbone consists of repeating disaccharide units: D-glucuronic acid (GlcUA)β1-3N-acetyl-D-galactosamine (GalNAc). Although CS participates in diverse biological processes such as growth factor signaling and the nervous system's development, the mechanism underlying the functions is not well understood. METHODS CS was isolated from ray fish cartilage, an industrial waste, and its structure and neurite outgrowth-promoting (NOP) activity were analyzed to investigate a potential application to nerve regeneration. RESULTS The major disaccharide unit in the CS preparation was GlcUA-GalNAc(6-O-sulfate) (61.9%). Minor proportions of GlcUA-GalNAc(4-O-sulfate) (27.0%), GlcUA(2-O-sulfate)-GalNAc(6-O-sulfate) (8.5%), and GlcUA-GalNAc (2.7%) were also detected. The preparation showed NOP activity in vitro, and this activity was suppressed by antibodies against hepatocyte growth factor (HGF) and its receptor c-Met, suggesting the involvement of the HGF signaling pathway in the expression of the in vitro NOP activity of the CS preparation. The specific binding of HGF to the CS preparation was also demonstrated by surface plasmon resonance spectroscopy. CONCLUSIONS AND GENERAL SIGNIFICANCE The NOP activity of CS from ray cartilage was demonstrated to be expressed through the HGF signaling pathway, suggesting that ray cartilage CS may be useful for studying the cooperative function of CS and HGF.