Receptor-Ligand Interaction Between CD44 and Osteopontin (Eta-1)

TLDR

The CD44 family of surface receptors regulates adhesion, movement, and activation of normal and neoplastic cells. Osteopontin binds CD44, stimulating chemotaxis without aggregation, whereas hyaluronate binding induces aggregation but not chemotaxis, suggesting distinct CD44‑mediated pathways that tumor cells could exploit for metastasis.

Abstract

The CD44 family of surface receptors regulates adhesion, movement, and activation of normal and neoplastic cells. The cytokine osteopontin (Eta-1), which regulates similar cellular functions, was found to be a protein ligand of CD44. Osteopontin induces cellular chemotaxis but not homotypic aggregation, whereas the inverse is true for the interaction between CD44 and a carbohydrate ligand, hyaluronate. The different responses of cells after CD44 ligation by either osteopontin or hyaluronate may account for the independent effects of CD44 on cell migration and growth. This mechanism may also be exploited by tumor cells to promote metastasis formation.