HSP72 INDUCTION BY HEAT-STRESS IN HUMAN NEURONS AND GLIAL-CELLS IN CULTURE

Expression of 72-kDa heat shock protein (HSP72) induced by heat stress was investigated in cultured neurons and glial cells isolated from fetal human brains using immunoblotting and immunocytochemistry. Under the unstressed condition, a low level of HSP72 expression was observed in astrocytes, microglia, oligodendrocytes, and neurons. Under the heat-stressed condition, an increased expression of HSP72 was observed in all cell types with specific location in the nuclear and cytoplasmic regions. Following heat stress, HSP72 was expressed intensely in more than 50% of astrocytes and microglia during 8-24 h post-recovery, while it was detectable in only 9% of oligodendrocytes and 3% of neurons at 48 h post-recovery. These results indicate that heat stress induces a predominant expression of HSP72 in astrocytes and microglia, and more limited HSP72 expression in oligodendrocytes and neurons in fetal human neural cells in culture. The differential patterns of HSP72 induction in human neural cells by heat stress suggest that cellular mechanisms by which the heat shock response is regulated are different among various cell types in the human central nervous system.