OVER-EXPRESSION OF HEAT-SHOCK-PROTEIN-70 PROTECTS NEURONAL CELLS AGAINST BOTH THERMAL AND ISCHEMIC STRESS BUT WITH DIFFERENT EFFICIENCIES

Primary cultures of dorsal root ganglia (DRG) sensory neurons can be p rotected against subsequent severe thermal or ischaemic stress by prio r exposure to a mild thermal or ischaemic insult. The degree of protec tion correlates with the amount of 70 kDa heat shock protein (hsp70) i nduced by the mild stress. We show directly that over-expression of hs p70 alone is sufficient to protect DRG neurons against thermal or isch aemic stress with a given level of hsp70 over-expression providing gre ater protection against thermal stress. In contrast overexpression of the 90 kDa heat shock protein (hsp90) has little or no protective effe ct against either stress. These results are discussed in terms of the role of individual hsps in protecting neuronal cells against different stresses.