Stimulation of erythroleukaemia cell differentiation by extracellular high-mobility group-box protein 1 is independent of the receptor for advanced glycation end-products.

In several cell types the binding of extracellular high-mobility group-box protein 1 (HMGB1) with the receptor for advanced glycation end-products (RAGE) induces cytoskeletal reorganization and cell motility. To establish whether RAGE is also involved in murine erythroleukaemia (MEL) cell differentiation stimulated by HMGB1, we have demonstrated that these cells express a 51 kDa protein identified as RAGE, and then we have produced stable transfectants overexpressing wild-type (wt) RAGE or a dominant negative (dn) RAGE mutant lacking the cytoplasmic domain to analyse the differentiation process in these cells. Several experimental findings indicated that RAGE was not involved in the MEL cell differentiation programme. This was also supported by the identical stimulatory effect exerted by HMGB1 on both wt- or dn-RAGE transfectants. We have also observed that HMGB1 binds a 65 kDa protein on the surface of MEL cells, supporting the hypothesis that alternative targets of HMGB1 are expressed on the MEL cell membrane and may be involved as mediators of its signalling.