HSP90 has neurite-promoting activity in vitro for telencephalic and spinalneurons of chick embryos

We purified a protein from the extract of denervated chick muscle. The prot ein had neurite-promoting activity in vitro for the chick telencephalic neu rons and spinal neurons. Partial amino acid sequencing and immunoblotting r evealed that the protein was chick heat shock protein 90 (HSP90). Commercia lly available bovine HSP90 and recombinant chick HSP90 expressed in Escheri chia coil also showed the same activity. Since HSP10 (GroES) and HSP60 (Gro EL) exhibited no activity for neurite outgrowth in the same culture, this a ctivity was specific to HSP90 among the heat shock proteins. (C) 1998 Acade mic Press.